TY  - JOUR
A1  - Kämpf, Lucas
A1  - Plessen, Birgit
A1  - Lauterbach, Stefan
A1  - Nantke, Carla
A1  - Meyer, Hanno
A1  - Chapligin, Bernhard
A1  - Brauer, Achim
T1  - Stable oxygen and carbon isotopes of carbonates in lake sediments as a paleoflood proxy
JF  - Geology / the Geological Society of America
N2  - Lake sediments are increasingly explored as reliable paleoflood archives. In addition to established flood proxies including detrital layer thickness, chemical composition, and grain size, we explore stable oxygen and carbon isotope data as paleoflood proxies for lakes in catchments with carbonate bedrock geology. In a case study from Lake Mondsee (Austria), we integrate high-resolution sediment trapping at a proximal and a distal location and stable isotope analyses of varved lake sediments to investigate flood-triggered detrital sediment flux. First, we demonstrate a relation between runoff, detrital sediment flux, and isotope values in the sediment trap record covering the period 2011-2013 CE including 22 events with daily (hourly) peak runoff ranging from 10 (24) m(3) s(-1) to 79 (110) m(3) s(-1). The three- to ten-fold lower flood-triggered detrital sediment deposition in the distal trap is well reflected by attenuated peaks in the stable isotope values of trapped sediments. Next, we show that all nine flood-triggered detrital layers deposited in a sediment record from 1988 to 2013 have elevated isotope values compared with endogenic calcite. In addition, even two runoff events that did not cause the deposition of visible detrital layers are distinguished by higher isotope values. Empirical thresholds in the isotope data allow estimation of magnitudes of the majority of floods, although in some cases flood magnitudes are overestimated because local effects can result in too-high isotope values. Hence we present a proof of concept for stable isotopes as reliable tool for reconstructing flood frequency and, although with some limitations, even for flood magnitudes.
KW  - detrital carbonate
KW  - varved sediments
KW  - record
KW  - Baldeggersee
KW  - delta-c-13
KW  - alps
Y1  - 2019
U6  - https://doi.org/10.1130/G46593.1
SN  - 1943-2682
SN  - 0091-7613
VL  - 48
IS  - 1
SP  - 3
EP  - 7
PB  - American Institute of Physics
CY  - Melville, NY
ER  - 
TY  - JOUR
A1  - Eibl, Eva P. S.
A1  - Hainzl, Sebastian
A1  - Vesely, Nele I. K.
A1  - Walter, Thomas R.
A1  - Jousset, Philippe
A1  - Hersir, Gylfi Pall
A1  - Dahm, Torsten
T1  - Eruption interval monitoring at strokkur Geyser, Iceland
JF  - Geophysical research letters
N2  - Geysers are hot springs whose frequency of water eruptions remain poorly understood. We set up a local broadband seismic network for 1 year at Strokkur geyser, Iceland, and developed an unprecedented catalog of 73,466 eruptions. We detected 50,135 single eruptions but find that the geyser is also characterized by sets of up to six eruptions in quick succession. The number of single to sextuple eruptions exponentially decreased, while the mean waiting time after an eruption linearly increased (3.7 to 16.4 min). While secondary eruptions within double to sextuple eruptions have a smaller mean seismic amplitude, the amplitude of the first eruption is comparable for all eruption types. We statistically model the eruption frequency assuming discharges proportional to the eruption multiplicity and a constant probability for subsequent events within a multituple eruption. The waiting time after an eruption is predictable but not the type or amplitude of the next one. <br /> Plain Language Summary Geysers are springs that often erupt in hot water fountains. They erupt more often than volcanoes but are quite similar. Nevertheless, it is poorly understood how often volcanoes and also geysers erupt. We created a list of 73,466 eruption times of Strokkur geyser, Iceland, from 1 year of seismic data. The geyser erupted one to six times in quick succession. We found 50,135 single eruptions but only 1 sextuple eruption, while the mean waiting time increased from 3.7 min after single eruptions to 16.4 min after sextuple eruptions. Mean amplitudes of each eruption type were higher for single eruptions, but all first eruptions in a succession were similar in height. Assuming a constant heat inflow at depth, we can predict the waiting time after an eruption but not the type or amplitude of the next one.
Y1  - 2019
U6  - https://doi.org/10.1029/2019GL085266
SN  - 0094-8276
SN  - 1944-8007
VL  - 47
IS  - 1
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Sobczyk, Artur
A1  - Sobel, Edward
A1  - Georgieva, Viktoria
T1  - Meso-Cenozoic cooling and exhumation history of the Orlica-snie(z) over dotnik Dome (Sudetes, NE Bohemian Massif, Central Europe)
BT  - insights from apatite fission-track thermochronometry
JF  - Terra nova
N2  - This study presents the first suite of apatite fission-track (AFT) ages from the SE part of the Western Sudetes. AFT cooling ages from the Orlica-snie(z) over dotnik Dome and the Upper Nysa Klodzka Graben range from Late Cretaceous (84 Ma) to Early Palaeocene-Middle Eocene (64-45 Ma). The first stage of basin evolution (similar to 100-90 Ma) was marked by the formation of a local extensional depocentre and disruption of the Mesozoic planation surface. Subsequent far-field convergence of European microplates resulted in Coniacian-Santonian (similar to 89-83 Ma) thrust faulting. AFT data from both metamorphic basement and Mesozoic sedimentary cover indicate homogenous Late Cretaceous burial of the entire Western Sudetes. Thermal history modeling suggests that the onset of cooling could be constrained between 89 and 63 Ma with a climax during the Palaeocene-Middle Eocene basin inversion phase.
Y1  - 2019
U6  - https://doi.org/10.1111/ter.12449
SN  - 0954-4879
SN  - 1365-3121
VL  - 32
IS  - 2
SP  - 122
EP  - 133
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Wickert, Andrew D.
A1  - Schildgen, Taylor F.
T1  - Long-profile evolution of transport-limited gravel-bed rivers
JF  - Earth surface dynamics
N2  - Alluvial and transport-limited bedrock rivers constitute the majority of fluvial systems on Earth. Their long profiles hold clues to their present state and past evolution. We currently possess first-principles-based governing equations for flow, sediment transport, and channel morphodynamics in these systems, which we lack for detachment-limited bedrock rivers. Here we formally couple these equations for transport-limited gravel-bed river long-profile evolution. The result is a new predictive relationship whose functional form and parameters are grounded in theory and defined through experimental data. From this, we produce a power-law analytical solution and a finite-difference numerical solution to long-profile evolution. Steady-state channel concavity and steepness are diagnostic of external drivers: concavity decreases with increasing uplift rate, and steepness increases with an increasing sediment-to-water supply ratio. Constraining free parameters explains common observations of river form: to match observed channel concavities, gravel-sized sediments must weather and fine - typically rapidly - and valleys typically should widen gradually. To match the empirical square-root width-discharge scaling in equilibrium-width gravel-bed rivers, downstream fining must occur. The ability to assign a cause to such observations is the direct result of a deductive approach to developing equations for landscape evolution.
Y1  - 2019
U6  - https://doi.org/10.5194/esurf-7-17-2019
SN  - 2196-6311
SN  - 2196-632X
VL  - 7
IS  - 1
SP  - 17
EP  - 43
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Schneider, K. P.
A1  - Hoffmann, J. E.
A1  - Münker, C.
A1  - Patyniak, Magda
A1  - Sprung, P.
A1  - Roerdink, D.
A1  - Garbe-Schönberg, D.
A1  - Kröner, A.
T1  - Petrogenetic evolution of metabasalts and metakomatiites of the lower Onverwacht Group, Barberton Greenstone Belt (South Africa)
JF  - Chemical geology : official journal of the European Association for Geochemistry
N2  - A well-preserved sequence, by Archean standards, of mantle-derived metabasalts and metakomatiites forms large parts of the lower Onverwacht Group of the Barberton Greenstone Belt (South Africa). To elucidate the origin of mafic and ultramafic rocks from this 3.55 to 3.45 Ga sequence, we present a comprehensive geochemical dataset including major and trace elements as well as Lu-Hf and Sm-Nd isotope compositions for a variety of metavolcanic rocks. These include metabasalts of the amphibolite-facies Sandspruit and Theespruit Formations as well as metabasalts and metakomatiites of the lower greenschist-facies Komati Formation. Based on their incompatible trace element patterns, the basalts of the Sandspruit and Theespruit Formations can be subdivided into a light rare earth element (LREE) depleted group, a LREE-undepleted group, and a LREE-enriched group. Positive epsilon Hf-(t) and epsilon Nd-(t) values of ca. +3 to +4 and 0 to +2, respectively, together with depletions in Th and La-CN/Yb-CN indicate derivation of the LREE-depleted basalts from a depleted mantle source. However, chondritic epsilon Hf-(t) and epsilon Nd-(t) values combined with positive Th and La-CN/Yb-CN of the LREE-enriched samples indicate a contribution from older granitoid crust in the petrogenesis of these samples. Trace element patterns of komatiites and basalts of the Komati Formation are generally flat relative to primitive mantle with slight depletions in heavy rare earth elements and Th and overall positive epsilon Hf-(t) of + 2.5 +/- 3.5 (2 s.d.) and epsilon Nd-(t) of + 0.5 +/- 2.2 (2 s. d.). The coherence in trace element characteristics suggests a common magmatic origin for basalts and komatiites. This study reveals that the two lavas were derived from the same mantle plume, i. e. komatiites were formed by high degrees of melting of a depleted mantle source containing residual garnet and the basalts were formed by moderate degrees of partial melting in shallower regions of the mantle. Based on the current dataset, combined with published data, we propose a geodynamic model for the oldest units of the Barberton Greenstone Belt that describes the development from a submerged continental setting (for the Sandspruit and Theespruit Formations) to a submarine plateau setting (for the Komati Formation) as a consequence of continental rifting.
KW  - Paleoarchean
KW  - Assimilation-fractional crystallization
KW  - Mantle source
KW  - Ancient Gneiss Complex
Y1  - 2019
U6  - https://doi.org/10.1016/j.chemgeo.2019.02.020
SN  - 0009-2541
SN  - 1872-6836
VL  - 511
SP  - 152
EP  - 177
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Greene, Chad A.
A1  - Thirumalai, Kaustubh
A1  - Kearney, Kelly A.
A1  - Delgado, Jose Miguel Martins
A1  - Schwanghart, Wolfgang
A1  - Wolfenbarger, Natalie S.
A1  - Thyng, Kristen M.
A1  - Gwyther, David E.
A1  - Gardner, Alex S.
A1  - Blankenship, Donald D.
T1  - The Climate Data Toolbox for MATLAB
JF  - Geochemistry, geophysics, geosystems
N2  - Climate science is highly interdisciplinary by nature, so understanding interactions between Earth processes inherently warrants the use of analytical software that can operate across the disciplines of Earth science. Toward this end, we present the Climate Data Toolbox for MATLAB, which contains more than 100 functions that span the major climate-related disciplines of Earth science. The toolbox enables streamlined, entirely scriptable workflows that are intuitive to write and easy to share. Included are functions to evaluate uncertainty, perform matrix operations, calculate climate indices, and generate common data displays. Documentation is presented pedagogically, with thorough explanations of how each function works and tutorials showing how the toolbox can be used to replicate results of published studies. As a well-tested, well-documented platform for interdisciplinary collaborations, the Climate Data Toolbox for MATLAB aims to reduce time spent writing low-level code, let researchers focus on physics rather than coding and encourage more efficacious code sharing. Plain Language Summary This article describes a collection of computer code that has recently been released to help scientists analyze many types of Earth science data. The code in this toolbox makes it easy to investigate things like global warming, El Nino, or other major climate-related processes such as how winds affect ocean circulation. Although the toolbox was designed to be used by expert climate scientists, its instruction manual is well written, and beginners may be able to learn a great deal about coding and Earth science, simply by following along with the provided examples. The toolbox is intended to help scientists save time, help them ensure their analysis is accurate, and make it easy for other scientists to repeat the results of previous studies.
Y1  - 2019
U6  - https://doi.org/10.1029/2019GC008392
SN  - 1525-2027
VL  - 20
IS  - 7
SP  - 3774
EP  - 3781
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Lopez, Jose P.
A1  - Altenberger, Uwe
A1  - Bellos, Laura I.
A1  - Günter, Christina
T1  - The Cumbres Calchaquies Range (NW-Argentina)
BT  - Geochemical sedimentary provenance, tectonic setting and metamorphic evolution of a Neoproterozoic sedimentary basin
JF  - Journal of South American earth sciences
N2  - The Cumbres Calchaquies Range forms part of the Famatinian metamorphic basement of the Eastern Sierras Pampeanas. The sedimentary protoliths of the metamorphic sequence were deposited in a marine basin alongside the western margin of Gondwana during the Neoproterozoic. New petrologic, geochemical and thermobarometric data give insight into the evolution of the sedimentary basin, its sediment source area, its later metamorphic overprint and its regional relationship to other parts of the Famatinian basement. The metamorphic series studied here consists of banded schists and gneisses and rare calcsilcate-rocks and migmatites that have been reworked by mid-to deep-crustal metamorphic and tectonic processes. The bulk rock compositions indicate shale, wacke, marl and litharenitic protoliths. The metamorphosed elastic sediments have major and trace element compositions indicating a continental granitoid-dominated source area with low sediment recycling. Low SiO2/Al2O3 ratios suggest a relatively low maturity of the sedimentary protoliths. Therefore, the Cumbres Calchaquies section represents a sequence of turbidity currents with progressive shallowing of the depositional environment, as indicated by quartz- and carbonate-rich sediments. The overall data are consistent with the geodynamic environment of a basin adjacent to a continental magmatic arc as the most probable scenario. Whereas the sedimentary protoliths of the metamorphic basement in the Sierra de Ancasti and Sierra de Aconquija, located ca 100-300 km south of the study area are interpreted as originating in an evolving back-arc basin, our results from the Cumbres Calchaquies region indicate a sedimentary source in a felsic continental arc with no significant influx of basic rocks. The Famatinian metamorphic evolution of the Cumbres Calchaquies rocks is of typical Barrow-type, culminating in partial melting of the metasediments. Conventional thermobarometry combined with thermodynamic models (pseudosections) reveal a prograde evolution reaching peak conditions of ca 665 degrees C/6.1 Kbar. This implies a geothermal gradient of ca 35 degrees C/km, which is slightly higher than the average for continental crust and suggests a period of crustal thinning, as known from back-arc basins, or additional heat supply by voluminous intrusions.
KW  - NW Argentina
KW  - Eastern Sierras Pampeanas
KW  - Cumbres Calchaquies
KW  - Geothermobarometry
KW  - Geochemistry
KW  - Metamorphic evolution
KW  - Provenance studies
Y1  - 2019
U6  - https://doi.org/10.1016/j.jsames.2019.03.016
SN  - 0895-9811
VL  - 93
SP  - 480
EP  - 494
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Dräger, Nadine
A1  - Plessen, Birgit
A1  - Kienel, Ulrike
A1  - Siowinski, Michat
A1  - Ramisch, Arne
A1  - Tjallingii, Rik
A1  - Pinkerneil, Sylvia
A1  - Brauer, Achim
T1  - Hypolimnetic oxygen conditions influence varve preservation and delta C-13 of sediment organic matter in Lake Tiefer See, NE Germany
JF  - Journal of paleolimnolog
N2  - Stable carbon isotopes of sediment organic matter (delta C-13(OM)) are widely applied in paleoenvironmental studies. Interpretations of delta C-13(OM), however, remain challenging and factors that influence delta C-13(OM) may not apply across all lakes. Common explanations for stratigraphic shifts in delta C-13(OM) include changes in lake productivity or changes in inputs of allochthonous OM. We investigated the influence of different oxygen conditions (oxic versus anoxic) on the delta C-13(OM) values in the sediments of Lake Tiefer See. We analysed (1) a long sediment core from the deepest part of the lake, (2) two short, sediment-water interface cores from shallower water depths, and (3) OM in the water column, i.e. from sediment traps. Fresh OM throughout the entire water column showed a relatively constant delta C-13(OM) value of approximately -30.5 parts per thousand. Similar values, about -31 parts per thousand, were obtained for well-varved sediments in both the long and short, sediment-water interface cores. In contrast, delta C-13(OM) values from non-varved sediments in all cores were significantly less negative (-29 parts per thousand). The delta C-13(OM) values in the sediment-water interface cores from different water depths differ for sediments of the same age, if oxygen conditions at the time of deposition were different at these sites, as suggested by the state of varve preservation. Sediments deposited from AD 1924 to 1980 at 62m water depth are varved and exhibit delta C-13(OM) values around -31 parts per thousand, whereas sediments of the same age in the core from 35m water depth are not varved and show less negative delta C-13(OM) values of about -29 parts per thousand. The relation between varve occurrence and delta C-13(OM) values suggests that delta C-13(OM) is associated with oxygen conditions because varve preservation depends on hypolimnetic anoxia. A mechanism that likely influences delta C-13(OM) is selective degradation of OM under oxic conditions, such that organic components with more negative delta C-13(OM) are preferably decomposed, leading to less negative delta C-13(OM) values in the remaining, undegraded OM pool. Greater decomposition of OM in non-varved sediments is supported by lower TOC concentrations in these deposits (similar to 5%) compared to well-varved sediments (similar to 15%). Even in lakes that display small variations in productivity and terrestrial OM input through time, large spatial and temporal differences in hypolimnetic oxygen concentrations may be an important factor controlling sediment delta C-13(OM).
KW  - Carbon stable isotopes
KW  - Hypolimnetic oxygen
KW  - Organic matter degradation
KW  - Varves
Y1  - 2019
U6  - https://doi.org/10.1007/s10933-019-00084-2
SN  - 0921-2728
SN  - 1573-0417
VL  - 62
IS  - 2
SP  - 181
EP  - 194
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Wang, Xiaoxi
A1  - Foster, William J.
A1  - Yan, J.
A1  - Li, A.
A1  - Mutti, Maria
T1  - Delayed recovery of metazoan reefs on the Laibin-Heshan platform margin following the Middle Permian (Capitanian) mass extinction
JF  - Global and planetary change
N2  - Following the Middle Permian (Capitanian) mass extinction there was a global ‘reef eclipse’, and this event had an important role in the Paleozoic-Mesozoic transition of reef ecosystems. Furthermore, the recovery pattern of reef ecosystems in the Wuchiapingian of South China, before the radiation of Changhsingian reefs, is poorly understood. Here, we present a detailed sedimentological account of the Tieqiao section, South China, which records the only known Wuchiapingian reef setting from South China. Six reef growing phases were identified within six transgressive-regressive cycles. The cycles represent changes of deposition in a shallow basin to a subtidal outer platform setting, and the reefal build-ups are recorded in the shallowest part of the cycles above wave base in the euphotic zone. Our results show that the initial reef recovery started from the shallowing up part of the 1st cycle, within the Clarkina leveni conodont zone, which is two conodont zones earlier than previously recognized. In addition, even though metazoans, such as sponges, do become important in the development of the reef bodies, they are not a major component until later in the Wuchiapingian in the 5th and 6th transgressive-regressive cycles. This suggests a delayed recovery of metazoan reef ecosystems following the Middle Permian extinction. Furthermore, even though sponges do become abundant within the reefs, it is the presence and growth of the encrusters Archaeolithoporella and Tubiphytes and abundance of microbial micrites that play an important role in stabilizing the reef structures that form topographic highs.
KW  - Reefs
KW  - Mass extinction
KW  - Wuchiapingian
KW  - Archaeolithoporella
KW  - Permian
Y1  - 2019
U6  - https://doi.org/10.1016/j.gloplacha.2019.05.005
SN  - 0921-8181
SN  - 1872-6364
VL  - 180
SP  - 1
EP  - 15
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Gefen-Treves, Shany
A1  - Kedem, Isaac
A1  - Weiss, Gad
A1  - Wagner, Dirk
A1  - Tchernov, Dan
A1  - Kaplan, Aaron
T1  - Acclimation of a rocky shore algal reef builder Neogoniolithon sp. to changing illuminations
JF  - Limnology and oceanography e-lectures / Association for the Sciences of Limnology and Oceanography
N2  - Vermetid reefs and rocky shores are hot spots of biodiversity, often referred to as the subtropical equivalent of coral reefs. The development of the ecosystem depends on the activity of several reef builders, including red crustose coralline algae (CCA) such as Neogoniolithon brassica-florida. Despite its importance, little is known about Neogoniolithon sp. acclimation to rapid changes in light intensity and corresponding photosynthetic activity. To overcome the large spatial variability in the light field (due to location and the porous nature of the rocks) we grew Neogoniolithon sp. on glass slides and characterized its photosynthetic performance in response to various light intensities by following O-2 exchange and fluorescence parameters. This was also performed on rock-inhabiting thalli collected from the east Mediterranean basin. Generally, maximal photosynthetic rate was reached when Neogoniolithon sp. thalli grown under low illumination (such as in protected niches where the light intensity can be as low as 1% of surface illumination) were examined. When exposed to light intensities higher than those experienced during growth, Neogoniolithon sp. activates adaptive/protective mechanisms such as state transition and nonphotochemical fluorescence quenching and increases the dark respiration thereafter. We find that the Fv/Fm parameter (variable/maximal fluorescence) is not suitable to assess photosynthetic performance in Neogoniolithon sp. and propose using instead an alternative parameter recently developed. Our findings help to clarify why Neogoniolithon sp. is usually observed in shaded niches along the reef surfaces.
Y1  - 2019
U6  - https://doi.org/10.1002/lno.11245
SN  - 0024-3590
SN  - 1939-5590
VL  - 65
IS  - 1
SP  - 27
EP  - 36
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Zhu, Chuanbin
A1  - Pilz, Marco
A1  - Cotton, Fabrice
T1  - Which is a better proxy, site period or depth to bedrock, in modelling linear site response in addition to the average shear-wave velocity?
JF  - Bulletin of earthquake engineering : official publication of the European Association for Earthquake Engineering
N2  - This study aims to identify the best-performing site characterization proxy alternative and complementary to the conventional 30 m average shear-wave velocity V-S30, as well as the optimal combination of proxies in characterizing linear site response. Investigated proxies include T-0 (site fundamental period obtained from earthquake horizontal-to-vertical spectral ratios), V-Sz (measured average shear-wave velocities to depth z, z = 5, 10, 20 and 30 m), Z(0.8) and Z(1.0) (measured site depths to layers having shear-wave velocity 0.8 and 1.0 km/s, respectively), as well as Z(x-infer) (inferred site depths from a regional velocity model, x = 0.8 and 1.0, 1.5 and 2.5 km/s). To evaluate the performance of a site proxy or a combination, a total of 1840 surface-borehole recordings is selected from KiK-net database. Site amplifications are derived using surface-to-borehole response-, Fourier- and cross-spectral ratio techniques and then are compared across approaches. Next, the efficacies of 7 single-proxies and 11 proxy-pairs are quantified based on the site-to-site standard deviation of amplification residuals of observation about prediction using the proxy or the pair. Our results show that T-0 is the best-performing single-proxy among T-0, Z(0.8), Z(1.0) and V-Sz. Meanwhile, T-0 is also the best-performing proxy among T-0, Z(0.8), Z(1.0) and Z(x-infer) complementary to V-S30 in accounting for the residual amplification after V-S30-correction. Besides, T-0 alone can capture most of the site effects and should be utilized as the primary site indicator. Though (T-0, V-S30) is the best-performing proxy pair among (V-S30, T-0), (V-S30, Z(0.8)), (V-S30, Z(1.0)), (V-S30, Z(x-infer)) and (T-0, V-Sz), it is only slightly better than (T-0, V-S20). Considering both efficacy and engineering utility, the combination of T-0 (primary) and V-S20 (secondary) is recommended. Further study is needed to test the performances of various proxies on sites in deep sedimentary basins.
KW  - Site effects
KW  - Amplification
KW  - Site proxy
KW  - Surface-to-borehole spectral ratios
KW  - KiK-net
KW  - Earthquake
Y1  - 2019
U6  - https://doi.org/10.1007/s10518-019-00738-6
SN  - 1570-761X
SN  - 1573-1456
VL  - 18
IS  - 3
SP  - 797
EP  - 820
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Herzschuh, Ulrike
T1  - Legacy of the Last Glacial on the present-day distribution of deciduous versus evergreen boreal forests
JF  - Global ecology and biogeography : a journal of macroecology
N2  - Issue Despite their rather similar climatic conditions, eastern Eurasia and northern North America are largely covered by different plant functional types (deciduous or evergreen boreal forest) composed of larch or pine, spruce and fir, respectively. I propose that these deciduous and evergreen boreal forests represent alternative quasi-stable states, triggered by their different northern tree refugia that reflect the different environmental conditions experienced during the Last Glacial. Evidence This view is supported by palaeoecological and environmental evidence. Once established, Asian larch forests are likely to have stabilized through a complex vegetation-fire-permafrost soil-climate feedback system. Conclusion With respect to future forest developments, this implies that Asian larch forests are likely to be governed by long-term trajectories and are therefore largely resistant to natural climate variability on time-scales shorter than millennia. The effects of regional human impact and anthropogenic global warming might, however, cause certain stability thresholds to be crossed, meaning that irreversible transitions occur and resulting in marked consequences for ecosystem services on these human-relevant time-scales.
KW  - boreal forests
KW  - Glacial refugia
KW  - Holocene
KW  - Larix larch
KW  - permafrost ecosystems
KW  - Palaeoecology
KW  - Siberia
KW  - vegetation-climate-fire-soil feedbacks
KW  - vegetation states
KW  - vegetation trajectories
Y1  - 2018
U6  - https://doi.org/10.1111/geb.13018
SN  - 1466-822X
SN  - 1466-8238
VL  - 29
IS  - 2
SP  - 198
EP  - 206
PB  - John Wiley & Sons, Inc.
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Barth, Sophia
A1  - Geertsema, Marten
A1  - Bevington, Alexandre R.
A1  - Bird, Alison L.
A1  - Clague, John J.
A1  - Millard, Tom
A1  - Bobrowsky, Peter T.
A1  - Hasler, Andreas
A1  - Liu, Hongjiang
T1  - Landslide response to the 27 October 2012 earthquake (M-W 7.8), southern Haida Gwaii, British Columbia, Canada
JF  - Landslides : journal of the International Consortium on Landslides, ICL
N2  - In this paper, we examine the influence of the 27 October 2012, M-w 7.8 earthquake on landslide occurrence in the southern half of Haida Gwaii (formerly Queen Charlotte Islands), British Columbia, Canada. Our 1350 km(2) study area is undisturbed, primarily forested terrain that has not experienced road building or timber harvesting. Our inventory of landslide polygons is based on optical airborne and spaceborne images acquired between 2007 and 2018, from which we extracted and mapped 446 individual landslides (an average of 33 landslides per 100 km(2)). The landslide rate in years without major earthquakes averages 19.4 per year, or 1.4/100 km(2)/year, and the annual average area covered by non-seismically triggered landslides is 35 ha/year. The number of landslides identified in imagery closely following the 2012 earthquake, and probably triggered by it, is 244 or an average of about 18 landslides per 100 km(2). These landslides cover a total area of 461 ha. In the following years-2013-2016 and 2016-2018-the number of landslides fell, respectively, to 26 and 13.5 landslides per year. In non-earthquake years, most landslides happen on south-facing slopes, facing the prevailing winds. In contrast, during or immediately after the earthquake, up to 32% of the landslides occurred on north and northwest-facing slopes. Although we could not find imagery from the day after the earthquake, overview reconnaissance flights 10 and 16 days later showed that most of the landslides were recent, suggesting they were co-seismic.
KW  - Landslide
KW  - Earthquake
KW  - British Columbia
KW  - Haida Gwaii
Y1  - 2019
U6  - https://doi.org/10.1007/s10346-019-01292-7
SN  - 1612-510X
SN  - 1612-5118
VL  - 17
IS  - 3
SP  - 517
EP  - 526
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Sublett, David Matthew
A1  - Sendula, Eszter
A1  - Lamadrid, Hector
A1  - Steele-MacInnis, Matthew
A1  - Spiekermann, Georg
A1  - Burruss, Robert C.
A1  - Bodnar, Robert J.
T1  - Shift in the Raman symmetric stretching band of N-2, CO2, and CH4 as a function of temperature, pressure, and density
JF  - Journal of Raman spectroscopy : JRS
N2  - The Raman spectra of pure N-2, CO2, and CH4 were analyzed over the range 10 to 500 bars and from -160 degrees C to 200 degrees C (N-2), 22 degrees C to 350 degrees C (CO2), and -100 degrees C to 450 degrees C (CH4). At constant temperature, Raman peak position, including the more intense CO2 peak (nu+), decreases (shifts to lower wave number) with increasing pressure for all three gases over the entire pressure and temperature (PT) range studied. At constant pressure, the peak position for CO2 and CH4 increases (shifts to higher wave number) with increasing temperature over the entire PT range studied. In contrast, N-2 first shows an increase in peak position with increasing temperature at constant pressure, followed by a decrease in peak position with increasing temperature. The inflection temperature at which the trend reverses for N-2 is located between 0 degrees C and 50 degrees C at pressures above similar to 50 bars and is pressure dependent. Below similar to 50 bars, the inflection temperature was observed as low as -120 degrees C. The shifts in Raman peak positions with PT are related to relative density changes, which reflect changes in intermolecular attraction and repulsion. A conceptual model relating the Raman spectral properties of N-2, CO2, and CH4 to relative density (volume) changes and attractive and repulsive forces is presented here. Additionally, reduced temperature-dependent densimeters and barometers are presented for each pure component over the respective PT ranges. The Raman spectral behavior of the pure gases as a function of temperature and pressure is assessed to provide a framework for understanding the behavior of each component in multicomponent N-2-CO2-CH4 gas systems in a future study.
KW  - fluids
KW  - wave number
KW  - attraction
KW  - repulsion
Y1  - 2019
U6  - https://doi.org/10.1002/jrs.5805
SN  - 0377-0486
SN  - 1097-4555
VL  - 51
IS  - 3
SP  - 555
EP  - 568
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Pourteau, Amaury
A1  - Scherer, Erik E.
A1  - Schorn, Simon
A1  - Bast, Rebecca
A1  - Schmidt, Alexander
A1  - Ebert, Lisa
T1  - Thermal evolution of an ancient subduction interface revealed by Lu-Hf garnet geochronology, Halilbagi Complex (Anatolia)
JF  - Geoscience Frontiers
N2  - The thermal structure of subduction zones exerts a major influence on deep-seated mechanical and chemical processes controlling arc magmatism, seismicity, and global element cycles. Accretionary complexes exposed inland may comprise tectonic blocks with contrasting pressure-temperature (P-T) histories, making it possible to investigate the dynamics and thermal evolution of former subduction interfaces. With this aim, we present new Lu-Hf geochronological results for mafic rocks of the Halilbagi Complex (Anatolia) that evolved along different thermal gradients. Samples include a lawsonite-epidote blueschist, a lawsonite-epidote eclogite, and an epidote eclogite (all with counter-clockwise P-T paths), a prograde lawsonite blueschist with a "hairpin"-type P-T path, and a garnet amphibolite from the overlying sub-ophiolitic metamorphic sole. Equilibrium phase diagrams suggest that the garnet amphibolite formed at similar to 0.6-0.7 GPa and 800-850 degrees C, whereas the prograde lawsonite blueschist records burial from 2.1 GPa and 420 degrees C to 2.6 GPa and 520 degrees C. Well-defined Lu-Hf isochrons were obtained for the epidote eclogite (92.38 +/- 0.22 Ma) and the lawsonite-epidote blueschist (90.19 +/- 0.54 Ma), suggesting rapid garnet growth. The lawsonite-epidote eclogite (87.30 +/- 0.39 Ma) and the prograde lawsonite blueschist (ca. 86 Ma) are younger, whereas the garnet amphibolite (104.5 +/- 3.5 Ma) is older. Our data reveal a consistent trend of progressively decreasing geothermal gradient from granulite-facies conditions at similar to 104 Ma to the epidote-eclogite facies around 92 Ma, and the lawsonite blueschist-facies between 90 Ma and 86 Ma. Three Lu-Hf garnet dates (between 92 Ma and 87 Ma) weighted toward the growth of post-peak rims (as indicated by Lu distribution in garnet) suggest that the HP/LT rocks were exhumed continuously and not episodically. We infer that HP/LT metamorphic rocks within the Halilbagi Complex were subjected to continuous return flow, with "warm" rocks being exhumed during the tectonic burial of "cold" ones. Our results, combined with regional geological constraints, allow us to speculate that subduction started at a transform fault near a mid-oceanic spreading centre. Following its formation, this ancient subduction interface evolved thermally over more than 15 Myr, most likely as a result of heat dissipation rather than crustal underplating. (C) 2018, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V.
KW  - Subduction
KW  - Lu/Hf dating of garnet
KW  - Metamorphic sole
KW  - Eclogite
KW  - Blueschist
KW  - Lawsonite
Y1  - 2019
U6  - https://doi.org/10.1016/j.gsf.2018.03.004
SN  - 1674-9871
VL  - 10
IS  - 1
SP  - 127
EP  - 148
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Petitgirard, Sylvian
A1  - Sahle, C. J.
A1  - Weis, C.
A1  - Gilmore, K.
A1  - Spiekermann, Georg
A1  - Tse, J. S.
A1  - Wilke, Max
A1  - Cavallari, C.
A1  - Cerantola, V
A1  - Sternemann, Christian
T1  - Magma properties at deep Earth’s conditions from electronic structure of silica
JF  - Geochemical perspectives letters
N2  - SiO(2 )is the main component of silicate melts and thus controls their network structure and physical properties. The compressibility and viscosities of melts at depth are governed by their short range atomic and electronic structure. We measured the O K-edge and the Si L-2,L-3-edge in silica up to 110 GPa using X-ray Raman scattering spectroscopy, and found a striking match to calculated spectra based on structures from molecular dynamic simulations. Between 20 and 27 GPa, Si-[4] species are converted into a mixture of Si-[5] and Si-[6] species and between 60 and 70 GPa, Si-[6] becomes dominant at the expense of Si-[5] with no further increase up to at least 110 GPa. Coordination higher than 6 is only reached beyond 140 GPa, corroborating results from Brillouin scattering. Network modifying elements in silicate melts may shift this change in coordination to lower pressures and thus magmas could be denser than residual solids at the depth of the core-mantle boundary.
Y1  - 2019
U6  - https://doi.org/10.7185/geochemlet.1902
SN  - 2410-339X
SN  - 2410-3403
VL  - 9
SP  - 32
EP  - 37
PB  - Association of Geochemistry
CY  - Paris
ER  - 
TY  - JOUR
A1  - Lanari, Pierre
A1  - Ferrero, Silvio
A1  - Goncalves, Philippe
A1  - Grosch, Eugene G.
T1  - Metamorphic geology
BT  - progress and perspectives
JF  - Geological Society
Y1  - 2019
SN  - 978-1-78620-400-4
U6  - https://doi.org/10.1144/SP478-2018-186
SN  - 0305-8719
SN  - 2041-4927
VL  - 478
SP  - 1
EP  - 12
PB  - Geological Society
CY  - London
ER  - 
TY  - JOUR
A1  - Geissler, Katja
A1  - Fiedler, Sebastian
A1  - Ni, Jian
A1  - Herzschuh, Ulrike
A1  - Jeltsch, Florian
T1  - Combined effects of grazing and climate warming drive shrub dominance on the Tibetan Plateau
JF  - The Rangeland journal
N2  - Encroachment of shrubs into the unique pastoral grassland ecosystems of the Tibetan Plateau has significant impact on ecosystem services, especially forage production. We developed a process-based ecohydrological model to identify the relative importance of the main drivers of shrub encroachment for the alpine meadows within the Qinghai province. Specifically, we explored the effects of summer livestock grazing (intensity and type of livestock) together with the effects of climate warming, including interactions between herbaceous and woody vegetation and feedback loops between soil, water and vegetation. Under current climatic conditions and a traditional herd composition, an increasing grazing intensity above a threshold value of 0.32 +/- 0.10 large stock units (LSU) ha(-1) day(-1) changes the vegetation composition from herbaceous towards a woody and bare soil dominated system. Very high grazing intensity (above 0.8 LSU ha(-1) day(-1)) leads to a complete loss of any vegetation. Under warmer conditions, the vegetation showed a higher resilience against livestock farming. This resilience is enhanced when the herd has a higher browser : grazer ratio. A cooler climate has a shrub encroaching effect, whereas warmer conditions increase the cover of the herbaceous vegetation. This effect was primarily due to season length and an accompanied competitive loss of slower growing shrubs, rather than evaporative water loss leading to less soil water in deeper soil layers for deeper rooting shrubs. If climate warming is driving current shrub encroachment, we conclude it is only indirectly so. It would be manifest by an advancing shrubline and could be regarded as a climatic escape of specific shrub species such as Potentilla fruticosa. Under the recent high intensity of grazing, only herding by more browsing animals can potentially prevent both shrub encroachment and the complete loss of herbaceous vegetation.
KW  - alpine grassland degradation
KW  - herd composition
KW  - rangeland management
KW  - shrub encroachment
KW  - shrubline
KW  - simulation model
Y1  - 2019
U6  - https://doi.org/10.1071/RJ19027
SN  - 1036-9872
SN  - 1834-7541
VL  - 41
IS  - 5
SP  - 425
EP  - 439
PB  - CSIRO Publishing
CY  - Collingwood
ER  - 
TY  - JOUR
A1  - Pereira, Bruno
A1  - Medeiros, Pedro Henrique Augusto
A1  - Francke, Till
A1  - Ramalho, Geraldo
A1  - Förster, Saskia
A1  - De Araujo, Jose Carlos
T1  - Assessment of the geometry and volumes of small surface water reservoirs by remote sensing in a semi-arid region with high reservoir density
JF  - Hydrological sciences journal = Journal des sciences hydrologiques
N2  - Water fluxes in highly impounded regions are heavily dependent on reservoir properties. However, for large and remote areas, this information is often unavailable. In this study, the geometry and volume of small surface reservoirs in the semi-arid region of Brazil were estimated using terrain and shape attributes extracted by remote sensing. Regression models and data classification were used to predict the volumes, at different water stages, of 312 reservoirs for which topographic information is available. The power function used to describe the reservoir shapes tends to overestimate the volumes; therefore, a modified shape equation was proposed. Among the methods tested, four were recommended based on performance and simplicity, for which the mean absolute percentage errors varied from 24 to 39%, in contrast to the 94% error achieved with the traditional method. Despite the challenge of precisely deriving the flooded areas of reservoirs, water management in highly reservoir-dense environments should benefit from volume prediction based on remote sensing.
KW  - reservoir volume
KW  - high-density reservoir network
KW  - water height-area-volume curve
KW  - semi-arid
KW  - remote sensing
Y1  - 2019
U6  - https://doi.org/10.1080/02626667.2019.1566727
SN  - 0262-6667
SN  - 2150-3435
VL  - 64
IS  - 1
SP  - 66
EP  - 79
PB  - Routledge, Taylor & Francis Group
CY  - Abingdon
ER  - 
TY  - JOUR
A1  - Ballato, Paolo
A1  - Brune, Sascha
A1  - Strecker, Manfred
T1  - Sedimentary loading–unloading cycles and faulting in intermontane basins
BT  - Insights from numerical modeling and field observations in the NW Argentine Andes
JF  - Earth & planetary science letters
N2  - The removal, redistribution, and transient storage of sediments in tectonically active mountain belts is thought to exert a first-order control on shallow crustal stresses, fault activity, and hence on the spatiotemporal pattern of regional deformation processes. Accordingly, sediment loading and unloading cycles in intermontane sedimentary basins may inhibit or promote intrabasinal faulting, respectively, but unambiguous evidence for this potential link has been elusive so far. Here we combine 2D numerical experiments that simulate contractional deformation in a broken-foreland setting (i.e., a foreland where shortening is diachronously absorbed by spatially disparate, reverse faults uplifting basement blocks) with field data from intermontane basins in the NW Argentine Andes. Our modeling results suggest that thicker sedimentary fills (>0.7-1.0 km) may suppress basinal faulting processes, while thinner fills (<0.7 km) tend to delay faulting. Conversely, the removal of sedimentary loads via fluvial incision and basin excavation promotes renewed intrabasinal faulting. These results help to better understand the tectono-sedimentary history of intermontane basins that straddle the eastern border of the Andean Plateau in northwestern Argentina. For example, the Santa Maria and the Humahuaca basins record intrabasinal deformation during or after sediment unloading, while the Quebrada del Toro Basin reflects the suppression of intrabasinal faulting due to loading by coarse conglomerates. We conclude that sedimentary loading and unloading cycles may exert a fundamental control on spatiotemporal deformation patterns in intermontane basins of tectonically active broken forelands. (C) 2018 Elsevier B.V. All rights reserved.
KW  - sedimentary loading and unloading cycles
KW  - intermontane basins
KW  - intrabasinal faulting
KW  - Argentinean broken foreland
KW  - 2D numerical experiments
KW  - Andes
Y1  - 2019
U6  - https://doi.org/10.1016/j.epsl.2018.10.043
SN  - 0012-821X
SN  - 1385-013X
VL  - 506
SP  - 388
EP  - 396
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Marc, Odin
A1  - Behling, Robert
A1  - Andermann, Christoff
A1  - Turowski, Jens M.
A1  - Illien, Luc
A1  - Roessner, Sigrid
A1  - Hovius, Niels
T1  - Long-term erosion of the Nepal Himalayas by bedrock landsliding
BT  - the role of monsoons, earthquakes and giant landslides
JF  - Earth surface dynamics
N2  - In active mountain belts with steep terrain, bedrock landsliding is a major erosional agent. In the Himalayas, landsliding is driven by annual hydro-meteorological forcing due to the summer monsoon and by rarer, exceptional events, such as earthquakes. Independent methods yield erosion rate estimates that appear to increase with sampling time, suggesting that rare, high-magnitude erosion events dominate the erosional budget. Nevertheless, until now, neither the contribution of monsoon and earthquakes to landslide erosion nor the proportion of erosion due to rare, giant landslides have been quantified in the Himalayas. We address these challenges by combining and analysing earthquake- and monsoon-induced landslide inventories across different timescales. With time series of 5 m satellite images over four main valleys in central Nepal, we comprehensively mapped landslides caused by the monsoon from 2010 to 2018. We found no clear correlation between monsoon properties and landsliding and a similar mean landsliding rate for all valleys, except in 2015, where the valleys affected by the earthquake featured similar to 5-8 times more landsliding than the pre-earthquake mean rate. The longterm size-frequency distribution of monsoon-induced landsliding (MIL) was derived from these inventories and from an inventory of landslides larger than similar to 0.1 km(2) that occurred between 1972 and 2014. Using a published landslide inventory for the Gorkha 2015 earthquake, we derive the size-frequency distribution for earthquakeinduced landsliding (EQIL). These two distributions are dominated by infrequent, large and giant landslides but under-predict an estimated Holocene frequency of giant landslides (> 1 km(3)) which we derived from a literature compilation. This discrepancy can be resolved when modelling the effect of a full distribution of earthquakes of variable magnitude and when considering that a shallower earthquake may cause larger landslides. In this case, EQIL and MIL contribute about equally to a total long-term erosion of similar to 2 +/- 0.75 mm yr(-1) in agreement with most thermo-chronological data. Independently of the specific total and relative erosion rates, the heavy-tailed size-frequency distribution from MIL and EQIL and the very large maximal landslide size in the Himalayas indicate that mean landslide erosion rates increase with sampling time, as has been observed for independent erosion estimates. Further, we find that the sampling timescale required to adequately capture the frequency of the largest landslides, which is necessary for deriving long-term mean erosion rates, is often much longer than the averaging time of cosmogenic Be-10 methods. This observation presents a strong caveat when interpreting spatial or temporal variability in erosion rates from this method. Thus, in areas where a very large, rare landslide contributes heavily to long-term erosion (as the Himalayas), we recommend Be-10 sample in catchments with source areas > 10 000 km(2) to reduce the method mean bias to below similar to 20 % of the long-term erosion.
Y1  - 2019
U6  - https://doi.org/10.5194/esurf-7-107-2019
SN  - 2196-6311
SN  - 2196-632X
VL  - 7
IS  - 1
SP  - 107
EP  - 128
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Kotha, Sreeram Reddy
A1  - Cotton, Fabrice
A1  - Bindi, Dino
T1  - Empirical models of shear-wave radiation pattern derived from large datasets of ground-shaking observations
JF  - Scientific reports
N2  - Shear-waves are the most energetic body-waves radiated from an earthquake, and are responsible for the destruction of engineered structures. In both short-term emergency response and long-term risk forecasting of disaster-resilient built environment, it is critical to predict spatially accurate distribution of shear-wave amplitudes. Although decades’ old theory proposes a deterministic, highly anisotropic, four-lobed shear-wave radiation pattern, from lack of convincing evidence, most empirical ground-shaking prediction models settled for an oversimplified stochastic radiation pattern that is isotropic on average. Today, using the large datasets of uniformly processed seismograms from several strike, normal, reverse, and oblique-slip earthquakes across the globe, compiled specifically for engineering applications, we could reveal, quantify, and calibrate the frequency-, distance-, and style-of-faulting dependent transition of shear-wave radiation between a stochastic-isotropic and a deterministic-anisotropic phenomenon. Consequent recalibration of empirical ground-shaking models dramatically improved their predictions: with isodistant anisotropic variations of ±40%, and 8% reduction in uncertainty. The outcomes presented here can potentially trigger a reappraisal of several practical issues in engineering seismology, particularly in seismic ground-shaking studies and seismic hazard and risk assessment.
Y1  - 2019
U6  - https://doi.org/10.1038/s41598-018-37524-4
SN  - 2045-2322
VL  - 9
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Bora, Sanjay Singh
A1  - Cotton, Fabrice
A1  - Scherbaum, Frank
T1  - NGA-West2 Empirical Fourier and Duration Models to Generate Adjustable Response Spectra
JF  - Earthquake spectra : the professional journal of the Earthquake Engineering Research Institute
N2  - Adjustment of median ground motion prediction equations (GMPEs) from one region to another region is one of the major challenges within the current practice of seismic hazard analysis. In our approach of generating response spectra, we derive two separate empirical models for a) Fourier amplitude spectrum (FAS) and b) duration of ground motion. To calculate response spectra, the two models are combined within the random vibration theory (RVT) framework. The models are calibrated on recordings obtained from shallow crustal earthquakes in active tectonic regions. We use a subset of NGA-West2 database with M3.2-7.9 earthquakes at distances 0-300 km. The NGA-West2 database expanded over a wide magnitude and distance range facilitates a better constraint over derived models. A frequency-dependent duration model is derived to obtain adjustable response spectral ordinates. Excellent comparison of our approach with other NGA-West2 models implies that it can also be used as a stand-alone model.
Y1  - 2019
U6  - https://doi.org/10.1193/110317EQS228M
SN  - 8755-2930
SN  - 1944-8201
VL  - 35
IS  - 1
SP  - 61
EP  - 93
PB  - Sage Publ.
CY  - Thousand Oaks
ER  - 
TY  - JOUR
A1  - Roda-Boluda, Duna C.
A1  - Whittaker, Alexander C.
A1  - Gheorghiu, Delia M.
A1  - Rodes, Angel
A1  - D'Arcy, Mitch
T1  - Be-10 erosion rates controlled by transient response to normal faulting through incision and landsliding
JF  - Earth & planetary science letters
N2  - Quantifying erosion rates, and how they compare to rock uplift rates, is fundamental for understanding landscape response to tectonics and associated sediment fluxes from upland areas. The erosional response to uplift is well-represented by river incision and the associated landslide activity. However, characterising the relationship between these processes remains a major challenge in tectonically active areas, in some cases because landslides can preclude obtaining reliable erosion rates from cosmogenic radionuclide (CRN) concentrations. Here, we quantify the control of tectonics and its coupled geomorphic response on the erosion rates of catchments in southern Italy that are experiencing a transient response to normal faulting. We analyse in-situ Be-10 concentrations for detrital sediment samples, collected along the strike of faults with excellent tectonic constraints and landslide inventories. We demonstrate that Be-10-derived erosion rates are controlled by fault throw rates and the extent of transient incision and associated landsliding in the catchments. We show that the low-relief sub-catchments above knickpoints erode at uniform background rates of similar to 0.10 mm/yr, while downstream of knickpoints, erosion removes similar to 50% of the rock uplifted by the faults, at rates of 0.10-0.64 mm/yr. Despite widespread landsliding, CRN samples provide relatively consistent and accurate erosion rates, most likely because landslides are frequent, small, and shallow, and represent the integrated record of landsliding over several seismic cycles. Consequently, we combine these validated Be-10 erosion rates and data from a geomorphological landslide inventory in a published numerical model, to gain further insight into the long-term landslide rates and sediment mixing, highlighting the potential of CRN data to study landslide dynamics. (C) 2018 Elsevier B.V. All rights reserved.
KW  - cosmogenic nuclides
KW  - erosion rates
KW  - normal faults
KW  - incision
KW  - landslides
KW  - transient response
Y1  - 2019
U6  - https://doi.org/10.1016/j.epsl.2018.11.032
SN  - 0012-821X
SN  - 1385-013X
VL  - 507
SP  - 140
EP  - 153
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Farkas, Márton Pál
A1  - Yoon, Jeoung Seok
A1  - Zang, Arno
A1  - Zimmermann, Günter
A1  - Stephansson, Ove
A1  - Lemon, Michael
A1  - Danko, Gyula
T1  - Effect of foliation and fluid viscosity on hydraulic fracturing tests in mica schists investigated using distinct element modeling and field data
JF  - Rock Mechanics and Rock Engineering
N2  - Several hydraulic fracturing tests were performed in boreholes located in central Hungary in order to determine the in-situ stress for a geological site investigation. At a depth of about 540m, the observed pressure versus time curves in mica schist with low dip angle foliation shows atypical pressure versus time results. After each pressurization cycle, the fracture breakdown pressure in the first fracturing cycle is lower than the refracturing or reopening pressure in the subsequent pressurizations. It is assumed that the viscosity of the drilling mud and observed foliation of the mica schist have a significant influence on the pressure values. In order to study this problem, numerical modeling was performed using the distinct element code particle flow code, which has been proven to be a valuable tool to investigate rock engineering problems such as hydraulic fracturing. The two-dimensional version of the code applied in this study can simulate hydro-mechanically coupled fluid flow in crystalline rock with low porosity and pre-existing fractures. In this study, the effect of foliation angle and fluid viscosity on the peak pressure is tested. The atypical characteristics of the pressure behaviour are interpreted so that mud with higher viscosity penetrates the sub-horizontal foliation plane, blocks the plane of weakness and makes the partly opened fracture tight and increase the pore pressure which decreases slowly with time. We see this viscous blocking effect as one explanation for the observed increase in fracture reopening pressure in subsequent pressurization cycles.
KW  - Hydraulic fracturing
KW  - Stress measurement
KW  - Particle flow code
KW  - Hydro-mechanical coupling
KW  - Microcrack
KW  - Viscous blocking
Y1  - 2019
U6  - https://doi.org/10.1007/s00603-018-1598-7
SN  - 0723-2632
SN  - 1434-453X
VL  - 52
IS  - 2
SP  - 555
EP  - 574
PB  - Springer
CY  - Wien
ER  - 
TY  - JOUR
A1  - Tomás, Sara
A1  - Aurell, Marcos
A1  - Badenas, Beatriz
A1  - Bjorge, Merle
A1  - Duaso, Maria
A1  - Mutti, Maria
T1  - Architecture and Paleoenvironment of Mid-Jurassic Microbial–Siliceous Sponge Mounds, Northeastern Spain
JF  - Journal of sedimentary research
N2  - The occurrence of mounds dominated by siliceous sponges and microbialites is often related to distal, deep settings of middle ramps and shelves. This paper presents evidence for Bajocian (Garanliana garantiana Zone) microbial-siliceous sponge mounds formed in open marine but relatively shallow settings of a ramp from the Iberian Basin of eastern Spain. Marked differences in mound spacing, morphology, and composition of the related intermound facies are observed from distal to more proximal settings. The distal (below storm wave base) settings are characterized by alternating tabular-bedded marls and limestones rich in pelagic fossils (ammonites, belemnites), open-marine thin-shelled bivalves (Bositra-like), as well as peloids, which include widely or randomly spaced isolated, small (up to 0.4 m high) and larger (up to 2.5 m high) mounds with upward accretion. The intermediate (near to above storm wave base) settings show tabular, thickened beds of peloidal and/or intraclastic limestones with closely spaced mounds (similar to 1 m high), which often coalesce laterally, forming extensive lenticular structures (up to 10 m wide). The proximal (above storm wave base) depositional settings consist of tabular to irregular beds of intraclastic limestones with widely spaced small (up to 0.4 m high) mounds with mainly tabular geometries. The mound framework contains variable proportions of microbialites (dense to clotted peloidal thrombolitic fabrics) and siliceous sponges (hexactinellids and lithistids in similar proportion) ranging from planar to conic shapes. These morphological and compositional changes allow characterizing three shallowing-upward sequences (sequences 1-3) developed in the overall regressive trend of a basin-wide, upper Bajocian T-R cycle. Episodic wave reworking of the early-cemented mounds resulted in the formation of peloids, small rounded intraclasts, and large, rounded or subangular intraclasts. These nonskeletal micritic grains show internal fabrics related to those of the mound and/or microbialites. A progressive textural gradation towards greater size and lesser roundness of the nonskeletal grains in the areas in the vicinity of the main mound factory is documented (i.e., from large, subangular intraclasts in the areas close to the main mound factory to peloids in the areas that are far from it). We discuss the alternative model of internal waves (instead of storm-induced waves) as the hydrodynamic agent providing the high-energy events needed to explain the origin of the peloidal-intraclastic intermound facies and, likely, also the nutrients needed by the microbialites and siliceous sponges to grow.
Y1  - 2019
U6  - https://doi.org/10.2110/jsr.2019.5
SN  - 1527-1404
SN  - 1938-3681
VL  - 89
IS  - 2
SP  - 110
EP  - 134
PB  - Society for Sedimentary Geology
CY  - Tulsa
ER  - 
TY  - JOUR
A1  - Karamzadeh, Nasim Toularoud
A1  - Kühn, Daniela
A1  - Kriegerowski, Marius
A1  - López-Comino, José Ángel
A1  - Cesca, Simone
A1  - Dahm, Torsten
T1  - Small-aperture array as a tool to monitor fluid injection- and extraction-induced microseismicity
BT  - applications and recommendations
JF  - Acta Geophysica
N2  - The monitoring of microseismicity during temporary human activities such as fluid injections for hydrofracturing, hydrothermal stimulations or wastewater disposal is a difficult task. The seismic stations often cannot be installed on hard rock, and at quiet places, noise is strongly increased during the operation itself and the installation of sensors in deep wells is costly and often not feasible. The combination of small-aperture seismic arrays with shallow borehole sensors offers a solution. We tested this monitoring approach at two different sites: (1) accompanying a fracking experiment in sedimentary shale at 4km depth and (2) above a gas field under depletion. The small-aperture arrays were planned according to theoretical wavenumber studies combined with simulations considering the local noise conditions. We compared array recordings with recordings available from shallow borehole sensors and give examples of detection and location performance. Although the high-frequency noise on the 50-m-deep borehole sensors was smaller compared to the surface noise before the injection experiment, the signals were highly contaminated during injection by the pumping activities. Therefore, a set of three small-aperture arrays at different azimuths was more suited to detect small events, since noise recorded on these arrays is uncorrelated with each other. Further, we developed recommendations for the adaptation of the monitoring concept to other sites experiencing induced seismicity.
KW  - Microseismic monitoring
KW  - Induced seismicity
KW  - Array seismology
KW  - Shallow borehole sensors
Y1  - 2019
U6  - https://doi.org/10.1007/s11600-018-0231-1
SN  - 1895-6572
SN  - 1895-7455
VL  - 67
IS  - 1
SP  - 311
EP  - 326
PB  - Springer
CY  - Cham
ER  - 
TY  - JOUR
A1  - Blayney, Tamsin
A1  - Dupont-Nivet, Guillaume
A1  - Najman, Yani
A1  - Proust, Jean-Noel
A1  - Meijer, Niels
A1  - Roperch, Pierrick
A1  - Sobel, Edward
A1  - Millar, Ian
A1  - Guo, Zhaojie
T1  - Tectonic Evolution of the Pamir Recorded in the Western Tarim Basin (China)
BT  - Sedimentologic and Magnetostratigraphic Analyses of the Aertashi Section
JF  - Tectonics
N2  - The northward indentation of the Pamir salient into the Tarim basin at the western syntaxis of the India-Asia collision zone is the focus of controversial models linking lithospheric to surface and atmospheric processes. Here we report on tectonic events recorded in the most complete and best-dated sedimentary sequences from the western Tarim basin flanking the eastern Pamir (the Aertashi section), based on sedimentologic, provenance, and magnetostratigraphic analyses. Increased tectonic subsidence and a shift from marine to continental fluvio-deltaic deposition at 41Ma indicate that far-field deformation from the south started to affect the Tarim region. A sediment accumulation hiatus from 24.3 to 21.6Ma followed by deposition of proximal conglomerates is linked to fault propagation into the Tarim basin. From 21.6 to 15.0Ma, increasing accumulation rates of fining upward clastics is interpreted as the expression of a major dextral transtensional system linking the Kunlun to the Tian Shan ahead of the northward Pamir indentation. At 15.0Ma, the appearance of North Pamir-sourced conglomerates followed at 11Ma by Central Pamir-sourced volcanics coincides with a shift to E-W compression, clockwise vertical-axis rotations and the onset of growth strata associated with the activation of the local east vergent Qimugen thrust wedge. Together, this enables us to interpret that Pamir indentation into Tarim had started by 24.3Ma, reached the study location by 15.0Ma and had passed it by 11Ma, providing kinematic constraints on proposed tectonic models involving intracontinental subduction and delamination.
KW  - India-Asia collision
KW  - Tarim basin
KW  - Pamir
KW  - Cenozoic
KW  - paleomagnetism
KW  - sedimentology
Y1  - 2019
U6  - https://doi.org/10.1029/2018TC005146
SN  - 0278-7407
SN  - 1944-9194
VL  - 38
IS  - 2
SP  - 492
EP  - 515
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Ripoll, Jean-Francois
A1  - Loridan, Vivien
A1  - Denton, Michael H.
A1  - Cunningham, Gregory
A1  - Reeves, G.
A1  - Santolik, O.
A1  - Fennell, Joseph
A1  - Turner, Drew L.
A1  - Drozdov, Alexander
A1  - Cervantes Villa, Juan Sebastian
A1  - Shprits, Yuri Y.
A1  - Thaller, Scott A.
A1  - Kurth, William S.
A1  - Kletzing, Craig A.
A1  - Henderson, Michael  G.
A1  - Ukhorskiy, Aleksandr Y.
T1  - Observations and Fokker-Planck Simulations of the L-Shell, Energy, and Times
JF  - Journal of geophysical research : Space physics
N2  - The evolution of the radiation belts in L-shell (L), energy (E), and equatorial pitch angle (alpha(0)) is analyzed during the calm 11-day interval (4-15 March) following the 1 March 2013 storm. Magnetic Electron and Ion Spectrometer (MagEIS) observations from Van Allen Probes are interpreted alongside 1D and 3D Fokker-Planck simulations combined with consistent event-driven scattering modeling from whistler mode hiss waves. Three (L, E, alpha(0)) regions persist through 11 days of hiss wave scattering; the pitch angle-dependent inner belt core (L similar to <2.2 and E < 700 keV), pitch angle homogeneous outer belt low-energy core (L > similar to 5 and E similar to < 100 keV), and a distinct pocket of electrons (L similar to [4.5, 5.5] and E similar to [0.7, 2] MeV). The pitch angle homogeneous outer belt is explained by the diffusion coefficients that are roughly constant for alpha(0) similar to <60 degrees, E > 100 keV, 3.5 < L < L-pp similar to 6. Thus, observed unidirectional flux decays can be used to estimate local pitch angle diffusion rates in that region. Top-hat distributions are computed and observed at L similar to 3-3.5 and E = 100-300 keV.
KW  - radiation belts
KW  - wave-particle interactions
KW  - electron lifetime
KW  - pitch angle diffusion coefficient
KW  - hiss waves
Y1  - 2018
U6  - https://doi.org/10.1029/2018JA026111
SN  - 2169-9380
SN  - 2169-9402
VL  - 124
IS  - 2
SP  - 1125
EP  - 1142
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Aseev, Nikita
A1  - Shprits, Yuri Y.
A1  - Wang, Dedong
A1  - Wygant, John
A1  - Drozdov, Alexander
A1  - Kellerman, Adam C.
A1  - Reeves, Geoffrey D.
T1  - Transport and loss of ring current electrons inside geosynchronous orbit during the 17 March 2013 storm
JF  - Journal of geophysical research : Space physics
N2  - Ring current electrons (1–100 keV) have received significant attention in recent decades, but many questions regarding their major transport and loss mechanisms remain open. In this study, we use the four‐dimensional Versatile Electron Radiation Belt code to model the enhancement of phase space density that occurred during the 17 March 2013 storm. Our model includes global convection, radial diffusion, and scattering into the Earth's atmosphere driven by whistler‐mode hiss and chorus waves. We study the sensitivity of the model to the boundary conditions, global electric field, the electric field associated with subauroral polarization streams, electron loss rates, and radial diffusion coefficients. The results of the code are almost insensitive to the model parameters above 4.5 RERE, which indicates that the general dynamics of the electrons between 4.5 RE and the geostationary orbit can be explained by global convection. We found that the major discrepancies between the model and data can stem from the inaccurate electric field model and uncertainties in lifetimes. We show that additional mechanisms that are responsible for radial transport are required to explain the dynamics of ≥40‐keV electrons, and the inclusion of the radial diffusion rates that are typically assumed in radiation belt studies leads to a better agreement with the data. The overall effect of subauroral polarization streams on the electron phase space density profiles seems to be smaller than the uncertainties in other input parameters. This study is an initial step toward understanding the dynamics of these particles inside the geostationary orbit.
KW  - ring current electrons
KW  - magnetospheric convection
KW  - ensemble modeling
KW  - inner magnetosphere
KW  - electron transport
KW  - wave-particle interactions
Y1  - 2019
U6  - https://doi.org/10.1029/2018JA026031
SN  - 2169-9380
SN  - 2169-9402
VL  - 124
IS  - 2
SP  - 915
EP  - 933
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Mikolaj, Michal
A1  - Reich, Marvin
A1  - Güntner, Andreas
T1  - Resolving geophysical signals by terrestrial gravimetry
BT  - a time domain assessment of the correction-induced uncertainty
JF  - Journal of geophysical research : Solid earth
N2  - Terrestrial gravimetry is increasingly used to monitor mass transport processes in geophysics boosted by the ongoing technological development of instruments. Resolving a particular phenomenon of interest, however, requires a set of gravity corrections of which the uncertainties have not been addressed up to now. In this study, we quantify the time domain uncertainty of tide, global atmospheric, large-scale hydrological, and nontidal ocean loading corrections. The uncertainty is assessed by comparing the majority of available global models for a suite of sites worldwide. The average uncertainty expressed as root-mean-square error equals 5.1nm/s(2), discounting local hydrology or air pressure. The correction-induced uncertainty of gravity changes over various time periods of interest ranges from 0.6nm/s(2) for hours up to a maximum of 6.7nm/s(2) for 6months. The corrections are shown to be significant and should be applied for most geophysical applications of terrestrial gravimetry. From a statistical point of view, however, resolving subtle gravity effects in the order of few nanometers per square second is challenged by the uncertainty of the corrections. Plain Language Summary Many scientists are exploring ways to benefit from gravity measurements in fields of high societal relevance such as monitoring of volcanoes or measuring the amount of water in underground. Any application of such new methods, however, requires careful preparation of the gravity measurements. The intention of the preparation process is to ensure that the measurements do not contain information about processes that are not of interest. For that reason, the influence of atmosphere, ocean, tides, and hydrology needs to be reduced from the gravity. In this study, we investigate how this reduction process influences the quality of the measurement. We found that the precision degrades especially owing to the hydrology. The ocean plays an important role at sites close to the coast and the atmosphere at sites located in mountains. The overall errors of the reductions may complicate a reliable use of gravity measurements in certain studies focusing on very small signals. Nevertheless, the precision of gravity reductions alone does not obstruct a meaningful use of gravity measurements in most research fields. Details specifying the reduction precision are provided in this study allowing scientist dealing with gravity measurements to decide if their signal of interest can be reliably resolved.
KW  - gravity observations
KW  - Earth tides
KW  - atmosphere
KW  - hydrology
KW  - nontidal ocean loading
Y1  - 2019
U6  - https://doi.org/10.1029/2018JB016682
SN  - 2169-9313
SN  - 2169-9356
VL  - 124
IS  - 2
SP  - 2153
EP  - 2165
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Bindi, Dino
A1  - Picozzi, Matteo
A1  - Spallarossa, Daniele
A1  - Cotton, Fabrice
A1  - Kotha, Sreeram Reddy
T1  - Impact of Magnitude Selection on Aleatory Variability Associated with Ground-Motion Prediction Equations
BT  - Part II-Analysis of the Between-Event Distribution in Central Italy
JF  - Bulletin of the Seismological Society of America
N2  - We derive a set of regional ground-motion prediction equations (GMPEs) in the Fourier amplitude spectra (FAS-GMPE) and in the spectral acceleration (SA-GMPE) domains for the purpose of interpreting the between-event residuals in terms of source parameter variability. We analyze a dataset of about 65,000 recordings generated by 1400 earthquakes (moment magnitude 2: 5 <= M-w <= 6: 5, hypocentral distance R-hypo <= 150 km) that occurred in central Italy between January 2008 and October 2017. In a companion article (Bindi, Spallarossa, et al., 2018), the nonparametric acceleration source spectra were interpreted in terms of omega-square models modified to account for deviations from a high-frequency flat plateau through a parameter named k(source). Here, the GMPEs are derived considering the moment (M-w), the local (M-L), and the energy (M-e) magnitude scales, and the between-event residuals are computed as random effects. We show that the between-event residuals for the FAS-GMPE implementing M-w are correlated with stress drop, with correlation coefficients increasing with increasing frequency up to about 10 Hz. Contrariwise, the correlation is weak for the FAS-GMPEs implementing M-L and M-e, in particular between 2 and 5 Hz, where most of the corner frequencies lie. At higher frequencies, all models show a strong correlation with k(source). The correlation with the source parameters reflects in a different behavior of the standard deviation tau of the between-event residuals with frequency. Although tau is smaller for the FAS-GMPE using M-w below 1.5 Hz, at higher frequencies, the model implementing either M-L or M-e shows smaller values, with a reduction of about 30% at 3 Hz (i.e., from 0.3 for M-w to 0.1 for M-L). We conclude that considering magnitude scales informative for the stress-drop variability allows to reduce the between-event variability with a significant impact on the hazard assessment, in particular for studies in which the ergodic assumption on site is removed.
Y1  - 2019
U6  - https://doi.org/10.1785/0120180239
SN  - 0037-1106
SN  - 1943-3573
VL  - 109
IS  - 1
SP  - 251
EP  - 262
PB  - Seismological Society of America
CY  - Albany
ER  - 
TY  - JOUR
A1  - Serrano, Paloma
A1  - Alawi, Mashal
A1  - de Vera, Jean-Pierre Paul
A1  - Wagner, Dirk
T1  - Response of Methanogenic Archaea from Siberian Permafrost and Non-permafrost Environments to Simulated Mars-like Desiccation and the Presence of Perchlorate
JF  - Astrobiology
N2  - Numerous preflight investigations were necessary prior to the exposure experiment BIOMEX on the International Space Station to test the basic potential of selected microorganisms to resist or even to be active under Mars-like conditions. In this study, methanogenic archaea, which are anaerobic chemolithotrophic microorganisms whose lifestyle would allow metabolism under the conditions on early and recent Mars, were analyzed. Some strains from Siberian permafrost environments have shown a particular resistance. In this investigation, we analyzed the response of three permafrost strains (Methanosarcina soligelidi SMA-21, Candidatus Methanosarcina SMA-17, Candidatus Methanobacterium SMA-27) and two related strains from non-permafrost environments (Methanosarcina mazei, Methanosarcina barkeri) to desiccation conditions (-80 degrees C for 315 days, martian regolith analog simulants S-MRS and P-MRS, a 128-day period of simulated Mars-like atmosphere). Exposure of the different methanogenic strains to increasing concentrations of magnesium perchlorate allowed for the study of their metabolic shutdown in a Mars-relevant perchlorate environment. Survival and metabolic recovery were analyzed by quantitative PCR, gas chromatography, and a new DNA-extraction method from viable cells embedded in S-MRS and P-MRS. All strains survived the two Mars-like desiccating scenarios and recovered to different extents. The permafrost strain SMA-27 showed an increased methanogenic activity by at least 10-fold after deep-freezing conditions. The methanogenic rates of all strains did not decrease significantly after 128 days S-MRS exposure, except for SMA-27, which decreased 10-fold. The activity of strains SMA-17 and SMA-27 decreased after 16 and 60 days P-MRS exposure. Non-permafrost strains showed constant survival and methane production when exposed to both desiccating scenarios. All strains showed unaltered methane production when exposed to the perchlorate concentration reported at the Phoenix landing site (2.4 mM) or even higher concentrations. We conclude that methanogens from (non-)permafrost environments are suitable candidates for potential life in the martian subsurface and therefore are worthy of study after space exposure experiments that approach Mars-like surface conditions.
KW  - Methanogenic archaea
KW  - Simulated Mars-like conditions
KW  - Subfreezing temperatures
KW  - Martian regolith analogs
KW  - Perchlorate
KW  - Permafrost
Y1  - 2019
U6  - https://doi.org/10.1089/ast.2018.1877
SN  - 1531-1074
SN  - 1557-8070
VL  - 19
IS  - 2
SP  - 197
EP  - 208
PB  - Liebert
CY  - New Rochelle
ER  - 
TY  - JOUR
A1  - Rodriguez-Zuluaga, Juan
A1  - Stolle, Claudia
T1  - Interhemispheric field-aligned currents at the edges of equatorial plasma depletions
JF  - Scientific reports
N2  - A comprehensive description of electromagnetic processes related to equatorial plasma depletions (EPDs) is essential for understanding their evolution and day-to-day variability. Recently, field-aligned currents (FACs) flowing at both western and eastern edges of EPDs were observed to be interhemispheric rather than anti-parallel about the dip equator, as suggested by previous theoretical studies. In this paper, we investigate the spatial and temporal variability of the FACs orientation using simultaneous measurements of electron density and magnetic field gathered by ESA’s Swarm constellation mission. By using empirical models, we assess the role of the Pedersen conductance in the preference of the FACs to close either in the northern or southern magnetic hemisphere. Here we show that the closure of the FACs agrees with an electrostatic regime determined by a hemispherical asymmetry of the Pedersen conductance. That is, the EPD-related FACs close at lower altitudes in the hemisphere with the highest conductivity. The evidence of this conclusion stands on the general agreement between the longitudinal and seasonal variability of both the conductivity and the FACs orientation.
Y1  - 2019
U6  - https://doi.org/10.1038/s41598-018-37955-z
SN  - 2045-2322
VL  - 9
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Walther, Sophia
A1  - Duveiller, Gregory
A1  - Jung, Martin
A1  - Guanter, Luis
A1  - Cescatti, Alessandro
A1  - Camps-Valls, Gustau
T1  - Satellite Observations of the Contrasting Response of Trees and Grasses to Variations in Water Availability
JF  - Geophysical research letters
N2  - Interannual variations in ecosystem primary productivity are dominated by water availability. Until recently, characterizing the photosynthetic response of different ecosystems to soil moisture anomalies was hampered by observational limitations. Here, we use a number of satellite-based proxies for productivity, including spectral indices, sun-induced chlorophyll fluorescence, and data-driven estimates of gross primary production, to reevaluate the relationship between terrestrial photosynthesis and water. In contrast to nonwoody vegetation, we find a resilience of forested ecosystems to reduced soil moisture. Sun-induced chlorophyll fluorescence and data-driven gross primary production indicate an increase in photosynthesis as a result of the accompanying higher amounts of light and temperature despite lowered light-use-efficiency. Conversely, remote sensing indicators of greenness reach their detection limit and largely remain stable. Our study thus highlights the differential responses of ecosystems along a tree cover gradient and illustrates the importance of differentiating photosynthesis indicators from those of greenness for the monitoring and understanding of ecosystems. Plain Language Summary The capacity of vegetation to thrive and to sequester carbon depends on how much water they can have access to. In this work, we evaluate how different types of satellite observations can describe the response of vegetation to changes in soil moisture over the entire planet. The first source of observation measures only the greenness of the land surface, the second measures light that is emitted by pigments in plants which are photosynthetically active (chlorophyll fluorescence), and the third are simulations of gross carbon uptake derived from machine learning techniques. For periods of water shortage all three indicate a reduction of growth in ecosystems with few trees. However, in cold boreal forests, when soil moisture is particularly low, we still detect an increase in photosynthesis due to higher light and temperature conditions, but this is not reflected in the greenness indicator. This work illustrates how lack of water is not necessarily harmful for catching carbon through photosynthesis, but to monitor this effect, we need remote sensing indicators that measure more than just how green the plants are, and fluorescence is likely a good candidate.
Y1  - 2019
U6  - https://doi.org/10.1029/2018GL080535
SN  - 0094-8276
SN  - 1944-8007
VL  - 46
IS  - 3
SP  - 1429
EP  - 1440
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Ulvrova, Martina M.
A1  - Brune, Sascha
A1  - Williams, Simon E.
T1  - Breakup Without Borders
BT  - How Continents Speed Up and Slow Down During Rifting
JF  - Geophysical research letters
N2  - Relative plate motions during continental rifting result from the interplay of local with far-field forces. Here we study the dynamics of rifting and breakup using large-scale numerical simulations of mantle convection with self-consistent evolution of plate boundaries. We show that continental separation follows a characteristic evolution with four distinctive phases: (1) an initial slow rifting phase with low divergence velocities and maximum tensional stresses, (2) a synrift speed-up phase featuring an abrupt increase of extension rate with a simultaneous drop of tensional stress, (3) the breakup phase with inception of fast sea-floor spreading, and (4) a deceleration phase occurring in most but not all models where extensional velocities decrease. We find that the speed-up during rifting is compensated by subduction acceleration or subduction initiation even in distant localities. Our study illustrates new links between local rift dynamics, plate motions, and subduction kinematics during times of continental separation.
Y1  - 2018
U6  - https://doi.org/10.1029/2018GL080387
SN  - 0094-8276
SN  - 1944-8007
VL  - 46
IS  - 3
SP  - 1338
EP  - 1347
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Gailleton, Boris
A1  - Mudd, Simon M.
A1  - Clubb, Fiona J.
A1  - Peifer, Daniel
A1  - Hurst, Martin D.
T1  - A segmentation approach for the reproducible extraction and quantification of knickpoints from river long profiles
JF  - Earth surface dynamics
N2  - Changes in the steepness of river profiles or abrupt vertical steps (i.e. waterfalls) are thought to be indicative of changes in erosion rates, lithology or other factors that affect landscape evolution. These changes are referred to as knickpoints or knickzones and are pervasive in bedrock river systems. Such features are thought to reveal information about landscape evolution and patterns of erosion, and therefore their locations are often reported in the geomorphic literature. It is imperative that studies reporting knickpoints and knickzones use a reproducible method of quantifying their locations, as their number and spatial distribution play an important role in interpreting tectonically active landscapes. In this contribution we introduce a reproducible knickpoint and knickzone extraction algorithm that uses river profiles transformed by integrating drainage area along channel length (the so-called integral or chi method). The profile is then statistically segmented and the differing slopes and step changes in the elevations of these segments are used to identify knickpoints, knickzones and their relative magnitudes. The output locations of identified knickpoints and knickzones compare favourably with human mapping: we test the method on Santa Cruz Island, CA, using previously reported knickzones and also test the method against a new dataset from the Quadrilatero Ferrifero in Brazil. The algorithm allows for the extraction of varying knickpoint morphologies, including stepped, positive slope-break (concave upward) and negative slope-break knickpoints. We identify parameters that most affect the resulting knickpoint and knickzone locations and provide guidance for both usage and outputs of the method to produce reproducible knickpoint datasets.
Y1  - 2019
U6  - https://doi.org/10.5194/esurf-7-211-2019
SN  - 2196-6311
SN  - 2196-632X
VL  - 7
IS  - 1
SP  - 211
EP  - 230
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Totz, Sonja Juliana
A1  - Petri, Stefan
A1  - Lehmann, Jascha
A1  - Peukert, Erik
A1  - Coumou, Dim
T1  - Exploring the sensitivity of Northern Hemisphere atmospheric circulation to different surface temperature forcing using a statistical-dynamical atmospheric model
JF  - Nonlinear processes in geophysics
N2  - Climate and weather conditions in the mid-latitudes are strongly driven by the large-scale atmosphere circulation. Observational data indicate that important components of the large-scale circulation have changed in recent decades, including the strength and the width of the Hadley cell, jets, storm tracks and planetary waves. Here, we use a new statistical-dynamical atmosphere model (SDAM) to test the individual sensitivities of the large-scale atmospheric circulation to changes in the zonal temperature gradient, meridional temperature gradient and global-mean temperature. We analyze the Northern Hemisphere Hadley circulation, jet streams, storm tracks and planetary waves by systematically altering the zonal temperature asymmetry, the meridional temperature gradient and the global-mean temperature. Our results show that the strength of the Hadley cell, storm tracks and jet streams depend, in terms of relative changes, almost linearly on both the global-mean temperature and the meridional temperature gradient, whereas the zonal temperature asymmetry has little or no influence. The magnitude of planetary waves is affected by all three temperature components, as expected from theoretical dynamical considerations. The width of the Hadley cell behaves nonlinearly with respect to all three temperature components in the SDAM. Moreover, some of these observed large-scale atmospheric changes are expected from dynamical equations and are therefore an important part of model validation.
Y1  - 2019
U6  - https://doi.org/10.5194/npg-26-1-2019
SN  - 1023-5809
SN  - 1607-7946
VL  - 26
IS  - 1
SP  - 1
EP  - 12
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Boers, Niklas
A1  - Goswami, Bedartha
A1  - Rheinwalt, Aljoscha
A1  - Bookhagen, Bodo
A1  - Hoskins, Brian
A1  - Kurths, Jürgen
T1  - Complex networks reveal global pattern of extreme-rainfall teleconnections
JF  - Nature : the international weekly journal of science
N2  - Climatic observables are often correlated across long spatial distances, and extreme events, such as heatwaves or floods, are typically assumed to be related to such teleconnections(1,2). Revealing atmospheric teleconnection patterns and understanding their underlying mechanisms is of great importance for weather forecasting in general and extreme-event prediction in particular(3,4), especially considering that the characteristics of extreme events have been suggested to change under ongoing anthropogenic climate change(5-8). Here we reveal the global coupling pattern of extreme-rainfall events by applying complex-network methodology to high-resolution satellite data and introducing a technique that corrects for multiple-comparison bias in functional networks. We find that the distance distribution of significant connections (P < 0.005) around the globe decays according to a power law up to distances of about 2,500 kilometres. For longer distances, the probability of significant connections is much higher than expected from the scaling of the power law. We attribute the shorter, power-law-distributed connections to regional weather systems. The longer, super-power-law-distributed connections form a global rainfall teleconnection pattern that is probably controlled by upper-level Rossby waves. We show that extreme-rainfall events in the monsoon systems of south-central Asia, east Asia and Africa are significantly synchronized. Moreover, we uncover concise links between south-central Asia and the European and North American extratropics, as well as the Southern Hemisphere extratropics. Analysis of the atmospheric conditions that lead to these teleconnections confirms Rossby waves as the physical mechanism underlying these global teleconnection patterns and emphasizes their crucial role in dynamical tropical-extratropical couplings. Our results provide insights into the function of Rossby waves in creating stable, global-scale dependencies of extreme-rainfall events, and into the potential predictability of associated natural hazards.
Y1  - 2019
U6  - https://doi.org/10.1038/s41586-018-0872-x
SN  - 0028-0836
SN  - 1476-4687
VL  - 566
IS  - 7744
SP  - 373
EP  - 377
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Page, M.
A1  - Licht, Alexis
A1  - Dupont-Nivet, Guillaume
A1  - Meijer, Niels
A1  - Barbolini, Natasha
A1  - Hoorn, C.
A1  - Schauer, A.
A1  - Huntington, K.
A1  - Bajnai, D.
A1  - Fiebig, J.
A1  - Mulch, Andreas
A1  - Guo, Z.
T1  - Synchronous cooling and decline in monsoonal rainfall in northeastern Tibet during the fall into the Oligocene icehouse
JF  - Geology
N2  - The fall into the Oligocene icehouse is marked by a steady decline in global temperature with punctuated cooling at the Eocene-Oligocene transition, both of which are well documented in the marine realm. However, the chronology and mechanisms of cooling on land remain unclear. Here, we use clumped isotope thermometry on northeastern Tibetan continental carbonates to reconstruct a detailed Paleogene surface temperature record for the Asian continental interior, and correlate this to an enhanced pollen data set. Our results show two successive dramatic (>9 degrees C) temperature drops, at 37 Ma and at 33.5 Ma. These large-magnitude decreases in continental temperatures can only be explained by a combination of both regional cooling and shifts of the rainy season to cooler months, which we interpret to reflect a decline of monsoonal intensity. Our results suggest that the response of Asian surface temperatures and monsoonal rainfall to the steady decline of atmospheric CO2 and global temperature through the late Eocene was nonlinear and occurred in two steps separated by a period of climatic instability. Our results support the onset of the Antarctic Circumpolar Current coeval to the Oligocene isotope event 1 (Oi-1) glaciation at 33.5 Ma, reshaping the distribution of surface heat worldwide; however, the origin of the 37 Ma cooling event remains less clear.
Y1  - 2019
U6  - https://doi.org/10.1130/G45480.1
SN  - 0091-7613
SN  - 1943-2682
VL  - 47
IS  - 3
SP  - 203
EP  - 206
PB  - American Institute of Physics
CY  - Boulder
ER  - 
TY  - JOUR
A1  - Plikk, Anna
A1  - Engels, Stefan
A1  - Luoto, Tomi P.
A1  - Nazarova, Larisa B.
A1  - Salonen, J. Sakari
A1  - Helmens, Karin F.
T1  - Chironomid-based temperature reconstruction for the Eemian Interglacial (MIS 5e) at Sokli, northeast Finland
JF  - Journal of paleolimnology
N2  - The Last Interglacial (Eemian, MIS 5e) can be considered a test-bed for climate dynamics under a warmer-than-present climate. In this study we present a chironomid record from the high latitude Sokli site (N Finland), where a long continuous sediment sequence from the last interglacial has been preserved from glacial erosion. The chironomid-analysis shows a diverse fauna, with dominance of warm-water indicators and shifts in assemblage composition that can be attributed to temperature, lake depth, productivity and habitat availability. Quantitative mean July paleotemperature estimates based on the chironomid data indicate overall mean July air temperatures up to 1 degrees C warmer than present. Two cooling events can be discerned, the Tunturi event, dated to about 127.5kaBP, in the lower part of the sequence, and the Varrio event, dated to about 119kaBP, associated with the beginning of a cooling trend in the upper part of the record. Warm conditions already at the onset of the interglacial contrast with a recent chironomid-based last interglacial temperature reconstruction from Denmark, which suggests a late onset of Eemian warming. The relatively small increase in inferred temperatures compared to present day temperatures at Sokli differs from other high latitude Eemian sites, and likely reflects the influence of the Atlantic Meridional Overturning Circulation in maintaining already elevated temperatures in Fennoscandia during interglacials.
KW  - Paleoclimate
KW  - Abrupt events
KW  - Last Interglacial
KW  - AMOC
KW  - Transfer functions
KW  - Validation
Y1  - 2019
U6  - https://doi.org/10.1007/s10933-018-00064-y
SN  - 0921-2728
SN  - 1573-0417
VL  - 61
IS  - 3
SP  - 355
EP  - 371
PB  - Springer Science
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Taran, Michail N.
A1  - Nunez Valdez, Maribel
A1  - Efthimiopoulos, Ilias
A1  - Müller, J.
A1  - Reichmann, Hans-Josef
A1  - Wilke, Max
A1  - Koch-Müller, Monika
T1  - Spectroscopic and ab initio studies of the pressure-induced Fe2+ high-spin-to-low-spin electronic transition in natural triphylite-lithiophilite
JF  - Physics and Chemistry of Minerals
N2  - Using optical absorption and Raman spectroscopic measurements, in conjunction with the first-principles calculations, a pressure-induced high-spin (HS)-to-low-spin (LS) state electronic transition of Fe2+ (M2-octahedral site) was resolved around 76-80GPa in a natural triphylite-lithiophilite sample with chemical composition (LiFe0.7082+Mn0.292PO4)-Li-M1-Fe-M2 (theoretical composition (LiFe0.52+Mn0.5PO4)-Li-M1-Fe-M2). The optical absorption spectra at ambient conditions consist of a broad doublet band with two constituents (1) (similar to 9330cm(-1)) and (2) (similar to 7110cm(-1)), resulting from the electronic spin-allowed transition (T2gEg)-T-5-E-5 of octahedral (HSFe2+)-Fe-M2. Both (1) and (2) bands shift non-linearly with pressure to higher energies up to similar to 55GPa. In the optical absorption spectrum measured at similar to 81GPa, the aforementioned HS-related bands disappear, whereas a new broadband with an intensity maximum close to 16,360cm(-1) appears, superimposed on the tail of the high-energy ligand-to-metal O2-Fe2+ charge-transfer absorption edge. We assign this new band to the electronic spin-allowed dd-transition (1)A(1g)(1)T(1g) of LS Fe2+ in octahedral coordination. The high-pressure Raman spectra evidence the Fe2+ HS-to-LS transition mainly from the abrupt shift of the P-O symmetric stretching modes to lower frequencies at similar to 76GPa, the highest pressure achieved in the Raman spectroscopic experiments. Calculations indicated that the presence of Mn-M2(2+) simply shifts the isostructural HS-to-LS transition to higher pressures compared to the triphylite Fe-M2(2+) end-member, in qualitative agreement with our experimental observations.
KW  - Phosphates
KW  - Triphylite
KW  - Raman
KW  - Infrared
KW  - Optical absorption spectroscopy
KW  - High pressure
KW  - Spin transition
KW  - DFT
Y1  - 2019
U6  - https://doi.org/10.1007/s00269-018-1001-y
SN  - 0342-1791
SN  - 1432-2021
VL  - 46
IS  - 3
SP  - 245
EP  - 258
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Trumbull, Robert B.
A1  - Sudo, Masafumi
A1  - Harris, C.
A1  - Armstrong, R. A.
A1  - de Beer, C. H.
T1  - The age of the Koegel Fontein anorogenic complex, South Africa, and its relationship to the regional timing of magmatism and breakup along the South Atlantic rifted margin
JF  - South African Journal of Geology
N2  - The early Cretaceous Koegel Fontein intrusive complex is situated near the Atlantic coast in South Africa, about 350 km northwest of Cape Town. The complex comprises felsic units of granite and syenite with compositionally related dykes, and a single intrusive plug of diorite. Existing zircon U-Pb ages of 144 +/- 2 Ma for the syenite and 133.9 +/- 1.3 Ma for the granite suggest that the emplacement of the complex took place over a period of about 10 My. This study provides additional and independent ages of the Koegel Fontein complex by Ar-40/Ar-39 dating to confirm the onset and duration of magmatism and better define the sequence of igneous units that comprise it. New laser step-heating Ar-40/Ar-3(9) ages on plagioclase and biotite from the main intrusive units in the complex are presented here, including samples previously dated by U-Pb dating. The Ar-40/Ar-39 ages for the granite and syenite units (131.1 +/- 0.9 Ma and 143.3 +/- 0.9, respectively) are in good agreement with the zircon U-Pb ages. Other units not previously dated include the Rooivleitjie alkaline granite (150.7 +/- 0.6 Ma), two quartz-porphyry dykes (143.0 +/- 0.9 and 139.4 +/- 1.7 Ma) and the Zout Rivier diorite plug (133.0 +/- 1.0 Ma). The new results confirm an early onset of magmatism at Koegel Fontein relative to that of the Etendeka Province some 1000 km to the north, which is consistent with the regional south-to-north propagation of South Atlantic rifting. The youngest Ar-40/Ar-3(9) ages at Koegel Fontein (134 to 131 Ma, Rietpoort Granite and 133 Ma, Zout Rivier diorite) correspond to the age of the first magnetic seafloor-spreading anomaly offshore, and we suggest that the longevity of Koegel Fontein magmatism relates to a superposition of pre-drift magmatism onshore and spreading-related magmatism as continental separation began.
Y1  - 2019
U6  - https://doi.org/10.25131/sajg.122.0007
SN  - 1012-0750
SN  - 1996-8590
VL  - 122
IS  - 1
SP  - 69
EP  - 78
PB  - Geological Society of South Africa
CY  - Marshalltown
ER  - 
TY  - JOUR
A1  - Hensch, Martin
A1  - Dahm, Torsten
A1  - Ritter, Joachim
A1  - Heimann, Sebastian
A1  - Schmidt, Bernd
A1  - Stange, Stefan
A1  - Lehmann, Klaus
T1  - Deep low-frequency earthquakes reveal ongoing magmatic recharge beneath Laacher See Volcano (Eifel, Germany)
JF  - Geophysical journal international
N2  - The occurrence of deep low-frequency (DLF) microearthquakes beneath volcanoes is commonly attributed to mass transport in the volcanic plumbing system and used to infer feeding channels from and into magma reservoirs. The key question is how magmas migrate from depth to the shallow crust and whether magma reservoirs are currently being recharged. For the first time since the improvement of the local seismic networks in the East Eifel region (Rhineland-Palatinate, Germany), we detect and locate recurrent DLF earthquakes in the lower crust and upper mantle beneath the Laacher See Volcano (LSV), using a joint data set of permanent sensors and a temporary deployment. So far, eight DLF earthquake sequences were observed in four distinct clusters between 10 and 40 km depth. These clusters of weak events (M-L< 2) align along an approximately 80. southeast dipping line south of the LSV. Moment tensor solutions of these events have large shear components, and the irregular dispersion and long coda of body waves indicate interaction processes between shear cracks and fluids. We find a rotation of P-axes orientation for shallow tectonic earthquakes compared to DLF events, indicating that the stress field in the depth interval of DLF events might favour a vertical migration of magma or magmatic fluids. The caldera of the LSV was formed by the last major eruption of the East Eifel Volcanic Field only 12.9 kyr ago, fed by a shallow magma chamber at 5-8 km depth and erupting a total magma volume of 6.7 km(3). The observed DLF earthquake activity and continuous volcanic gas emissions around the LSV indicate an active magmatic system, possibly connected with an upper mantle melt zone.
KW  - Waveform inversion
KW  - Volcano seismology
KW  - Magma migration and fragmentation
KW  - Volcano monitoring
Y1  - 2019
U6  - https://doi.org/10.1093/gji/ggy532
SN  - 0956-540X
SN  - 1365-246X
VL  - 216
IS  - 3
SP  - 2025
EP  - 2036
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - de Gelder, Gino
A1  - Fernandez-Blanco, David
A1  - Melnick, Daniel
A1  - Duclaux, Guillaume
A1  - Bell, Rebecca E.
A1  - Jara Muñoz, Julius
A1  - Armijo, Rolando
A1  - Lacassin, Robin
T1  - Lithospheric flexure and rheology determined by climate cycle markers in the Corinth Rift
JF  - Scientific reports
N2  - Geomorphic strain markers accumulating the effects of many earthquake cycles help to constrain the mechanical behaviour of continental rift systems as well as the related seismic hazards. In the Corinth Rift (Greece), the unique record of onshore and offshore markers of Pleistocene similar to 100-ka climate cycles provides an outstanding possibility to constrain rift mechanics over a range of timescales. Here we use high-resolution topography to analyse the 3D geometry of a sequence of Pleistocene emerged marine terraces associated with flexural rift-flank uplift. We integrate this onshore dataset with offshore seismic data to provide a synoptic view of the flexural deformation across the rift. This allows us to derive an average slip rate of 4.5-9.0 mm.yr(-1) on the master fault over the past similar to 610 ka and an uplift/ subsidence ratio of 1:1.1-2.4. We reproduce the observed flexure patterns, using 3 and 5-layered lithospheric scale finite element models. Modelling results imply that the observed elastic flexure is produced by coseismic slip along 40-60 degrees planar normal faults in the elastic upper crust, followed by postseismic viscous relaxation occurring within the basal lower crust or upper mantle. We suggest that such a mechanism may typify rapid localised extension of continental lithosphere.
Y1  - 2019
U6  - https://doi.org/10.1038/s41598-018-36377-1
SN  - 2045-2322
VL  - 9
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Treat, Claire C.
A1  - Kleinen, Thomas
A1  - Broothaerts, Nils
A1  - Dalton, April S.
A1  - Dommain, Rene
A1  - Douglas, Thomas A.
A1  - Drexler, Judith Z.
A1  - Finkelstein, Sarah A.
A1  - Grosse, Guido
A1  - Hope, Geoffrey
A1  - Hutchings, Jack
A1  - Jones, Miriam C.
A1  - Kuhry, Peter
A1  - Lacourse, Terri
A1  - Lahteenoja, Outi
A1  - Loisel, Julie
A1  - Notebaert, Bastiaan
A1  - Payne, Richard J.
A1  - Peteet, Dorothy M.
A1  - Sannel, A. Britta K.
A1  - Stelling, Jonathan M.
A1  - Strauss, Jens
A1  - Swindles, Graeme T.
A1  - Talbot, Julie
A1  - Tarnocai, Charles
A1  - Verstraeten, Gert
A1  - Williams, Christopher J.
A1  - Xia, Zhengyu
A1  - Yu, Zicheng
A1  - Valiranta, Minna
A1  - Hattestrand, Martina
A1  - Alexanderson, Helena
A1  - Brovkin, Victor
T1  - Widespread global peatland establishment and persistence over the last 130,000 y
JF  - Proceedings of the National Academy of Sciences of the United States of America
N2  - Glacial-interglacial variations in CO2 and methane in polar ice cores have been attributed, in part, to changes in global wetland extent, but the wetland distribution before the Last Glacial Maximum (LGM, 21 ka to 18 ka) remains virtually unknown. We present a study of global peatland extent and carbon (C) stocks through the last glacial cycle (130 ka to present) using a newly compiled database of 1,063 detailed stratigraphic records of peat deposits buried by mineral sediments, as well as a global peatland model. Quantitative agreement between modeling and observations shows extensive peat accumulation before the LGM in northern latitudes (> 40 degrees N), particularly during warmer periods including the last interglacial (130 ka to 116 ka, MIS 5e) and the interstadial (57 ka to 29 ka, MIS 3). During cooling periods of glacial advance and permafrost formation, the burial of northern peatlands by glaciers and mineral sediments decreased active peatland extent, thickness, and modeled C stocks by 70 to 90% from warmer times. Tropical peatland extent and C stocks show little temporal variation throughout the study period. While the increased burial of northern peats was correlated with cooling periods, the burial of tropical peat was predominately driven by changes in sea level and regional hydrology. Peat burial by mineral sediments represents a mechanism for long-term terrestrial C storage in the Earth system. These results show that northern peatlands accumulate significant C stocks during warmer times, indicating their potential for C sequestration during the warming Anthropocene.
KW  - peatlands
KW  - carbon
KW  - methane
KW  - carbon burial
KW  - Quaternary
Y1  - 2019
U6  - https://doi.org/10.1073/pnas.1813305116
SN  - 0027-8424
VL  - 116
IS  - 11
SP  - 4822
EP  - 4827
PB  - National Acad. of Sciences
CY  - Washington
ER  - 
TY  - JOUR
A1  - Martinez-Garvon, Patricia
A1  - Bohnhoff, Marco
A1  - Mencin, David
A1  - Kwiatek, Grzegorz
A1  - Dresen, Georg
A1  - Hodgkinson, Kathleen
A1  - Nurlu, Murat
A1  - Kadirioglu, Filiz Tuba
A1  - Kartal, Recai Feyiz
T1  - Slow strain release along the eastern Marmara region offshore Istanbul in conjunction with enhanced local seismic moment release
JF  - Earth & planetary science letters
N2  - We analyze a large transient strainmeter signal recorded at 62.5 m depth along the southern shore of the eastern Sea of Marmara region in northwestern Turkey. This region represents a passage of stress transfer from the Izmit rupture to the Marmara seismic gap. The strain signal was recorded at the Esenkoy site by one of the ICDP-GONAF (International Continental Drilling Programme - Geophysical Observatory at the North Anatolian Fault) strainmeters on the Armutlu peninsula with a maximum amplitude of 5 microstrain and lasting about 50 days. The onset of the strain signal coincided with the origin time of a M-w 4.4 earthquake offshore Yalova, which occurred as part of a seismic sequence including eight M-w >= 3.5 earthquakes. The Mw 4.4 event occurred at a distance of about 30 km from Esenkoy on June 25th 2016 representing the largest earthquake in this region since 2008. Before the event, the maximum horizontal strain was subparallel to the regional maximum horizontal stress derived from stress inversion of local seismicity. During the strain transient, we observe a clockwise rotation in the local horizontal strain field of about 20 degrees. The strain signal does not correlate with known environmental parameters such as annual changes of sea level, rainfall or temperature. The strain signal could indicate local slow slip on the Cinarcik fault and thus a transfer of stress to the eastern Marmara seismic gap.
KW  - strain transient
KW  - slow slip
KW  - transform faults
KW  - seismic hazard
KW  - strainmeter data
KW  - Sea of Marmara
Y1  - 2019
U6  - https://doi.org/10.1016/j.epsl.2019.01.001
SN  - 0012-821X
SN  - 1385-013X
VL  - 510
SP  - 209
EP  - 218
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Meijer, Niels
A1  - Dupont-Nivet, Guillaume
A1  - Abels, Hemmo A.
A1  - Kaya, Mustafa Y.
A1  - Licht, Alexis
A1  - Xiao, Meimei
A1  - Zhang, Yang
A1  - Roperch, Pierrick
A1  - Poujol, Marc
A1  - Lai, Zhongping
A1  - Guo, Zhaojie
T1  - Central Asian moisture modulated by proto-Paratethys Sea incursions since the early Eocene
JF  - Earth and planetary science letters
N2  - The establishment and evolution of the Asian monsoons and arid interior have been linked to uplift of the Tibetan Plateau, retreat of the inland proto-Paratethys Sea and global cooling during the Cenozoic. However, the respective role of these driving mechanisms remains poorly constrained. This is partly due to a lack of continental records covering the key Eocene epoch marked by the onset of Tibetan Plateau uplift, proto-Paratethys Sea incursions and long-term global cooling. In this study, we reconstruct paleoenvironments in the Xining Basin, NE Tibet, to show a long-term drying of the Asian continental interior from the early Eocene to the Oligocene. Superimposed on this trend are three alternations between arid mudflat and wetter saline lake intervals, which are interpreted to reflect atmospheric moisture fluctuations in the basin. We date these fluctuations using magnetostratigraphy and the radiometric age of an intercalated tuff layer. The first saline lake interval is tentatively constrained to the late Paleocene-early Eocene. The other two are firmly dated between similar to 46 Ma (top magnetochron C21n) and similar to 41 Ma (base C18r) and between similar to 40 Ma (base C18n) and similar to 37 Ma (top C17n). Remarkably, these phases correlate in time with highstands of the proto-Paratethys Sea. This strongly suggests that these sea incursions enhanced westerly moisture supply as far inland as the Xining Basin. We conclude that the proto-Paratethys Sea constituted a key driver of Asian climate and should be considered in model and proxy interpretations. (C) 2019 Elsevier B.V. All rights reserved.
KW  - Paleogene
KW  - magnetostratigraphy
KW  - Central Asia
KW  - Xining Basin
KW  - westerlies
KW  - Asian monsoon
Y1  - 2019
U6  - https://doi.org/10.1016/j.epsl.2018.12.031
SN  - 0012-821X
SN  - 1385-013X
VL  - 510
SP  - 73
EP  - 84
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Boit, Alice
A1  - Spencer, Matthew
T1  - Equivalence and dissimilarity of ecosystem states
JF  - Ecological modelling : international journal on ecological modelling and engineering and systems ecolog
N2  - Measuring (dis)similarity between ecosystem states is a key theme in ecology. Much of community and ecosystem ecology is devoted to searching for patterns in ecosystem similarity from an external observer's viewpoint, using variables such as species abundances, measures of diversity and complexity. However, from the point of view of organisms in the ecosystem, proportional population growth rates are the only relevant aspect of ecosystem state, because natural selection acts on groups of organisms with different proportional population growth rates. We therefore argue that two ecosystem states are equivalent if and only if, for each species they contain, the proportional population growth rate does not differ between the states. Based on this result, we develop species-level and aggregated summary measures of ecosystem state and discuss their ecological meaning. We illustrate our approach using a long-term dataset on the plankton community from the Central European Lake Constance. We show that the first three principal components of proportional population growth rates describe most of the variation in ecosystem state in Lake Constance. We strongly recommend using proportional population growth rates and the derived equivalence classes for comparative ecosystem studies. This opens up new perspectives on important existing topics such as alternative stable ecosystem states, community assembly, and the processes generating regularities in ecosystems.
KW  - Hutchinson niche
KW  - Ecosystem dynamics
KW  - Ecosystem dissimilarity
KW  - Proportional population growth rate
KW  - Per capita growth rate
Y1  - 2019
U6  - https://doi.org/10.1016/j.ecolmodel.2019.01.009
SN  - 0304-3800
SN  - 1872-7026
VL  - 396
SP  - 12
EP  - 22
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Reschke, Maria
A1  - Rehfeld, Kira
A1  - Laepple, Thomas
T1  - Empirical estimate of the signal content of Holocene temperature proxy records
JF  - Climate of the past : an interactive open access journal of the European Geosciences Union
N2  - Proxy records from climate archives provide evidence about past climate changes, but the recorded signal is affected by non-climate-related effects as well as time uncertainty. As proxy-based climate reconstructions are frequently used to test climate models and to quantitatively infer past climate, we need to improve our understanding of the proxy record signal content as well as the uncertainties involved. In this study, we empirically estimate signal-to-noise ratios (SNRs) of temperature proxy records used in global compilations of the middle to late Holocene (last 6000 years). This is achieved through a comparison of the correlation of proxy time series from nearby sites of three compilations and model time series extracted at the proxy sites from two transient climate model simulations: a Holocene simulation of the ECHAM5/MPI-OM model and the Holocene part of the TraCE-21ka simulation. In all comparisons, we found the mean correlations of the proxy time series on centennial to millennial timescales to be low (R < 0.2), even for nearby sites, which resulted in low SNR estimates. The estimated SNRs depend on the assumed time uncertainty of the proxy records, the timescale analysed, and the model simulation used. Using the spatial correlation structure of the ECHAM5/MPI-OM simulation, the estimated SNRs on centennial timescales ranged from 0.05 - assuming no time uncertainty - to 0.5 for a time uncertainty of 400 years. On millennial timescales, the estimated SNRs were generally higher. Use of the TraCE-21ka correlation structure generally resulted in lower SNR estimates than for ECHAM5/MPI-OM. As the number of available high-resolution proxy records continues to grow, a more detailed analysis of the signal content of specific proxy types should become feasible in the near future. The estimated low signal content of Holocene temperature compilations should caution against over-interpretation of these multi-proxy and multisite syntheses until further studies are able to facilitate a better characterisation of the signal content in paleoclimate records.
Y1  - 2019
U6  - https://doi.org/10.5194/cp-15-521-2019
SN  - 1814-9324
SN  - 1814-9332
VL  - 15
IS  - 2
SP  - 521
EP  - 537
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Cucchi, Karma
A1  - Hesse, Falk
A1  - Kawa, Nura
A1  - Wang, Changhong
A1  - Rubin, Yoram
T1  - Ex-situ priors: A Bayesian hierarchical framework for defining informative prior distributions in hydrogeology
JF  - Advances in water resources
N2  - Stochastic modeling is a common practice for modeling uncertainty in hydrogeology. In stochastic modeling, aquifer properties are characterized by their probability density functions (PDFs). The Bayesian approach for inverse modeling is often used to assimilate information from field measurements collected at a site into properties’ posterior PDFs. This necessitates the definition of a prior PDF, characterizing the knowledge of hydrological properties before undertaking any investigation at the site, and usually coming from previous studies at similar sites. In this paper, we introduce a Bayesian hierarchical algorithm capable of assimilating various information–like point measurements, bounds and moments–into a single, informative PDF that we call ex-situ prior. This informative PDF summarizes the ex-situ information available about a hydrogeological parameter at a site of interest, which can then be used as a prior PDF in future studies at the site. We demonstrate the behavior of the algorithm on several synthetic case studies, compare it to other methods described in the literature, and illustrate the approach by applying it to a public open-access hydrogeological dataset.
KW  - Data assimilation
KW  - Data fusion
KW  - Bayesian hierarchical model
KW  - Informative prior
KW  - Databases
Y1  - 2019
U6  - https://doi.org/10.1016/j.advwatres.2019.02.003
SN  - 0309-1708
SN  - 1872-9657
VL  - 126
SP  - 65
EP  - 78
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Pingel, Heiko
A1  - Schildgen, Taylor F.
A1  - Strecker, Manfred
A1  - Wittmann, Hella
T1  - Pliocene-Pleistocene orographic control on denudation in northwest Argentina
JF  - Geology
N2  - The intermontane Humahuaca Basin in the Eastern Cordillera of the northwest Argentine Andes lies leeward of an orographic barrier to easterly derived moisture. An average of >2000 mm/yr of rainfall along the eastern flanks of the barrier contrasts with <200 mm/yr in the orogen interior. Paleoenvironmental reconstructions suggest that the basin became disconnected from the foreland during the Miocene-Pliocene by the growth of fault-bounded mountain ranges. Fossil records, sedimentology, and stable isotope data imply that rerouting of the fluvial network by 4.2 Ma and reduced rainfall by ca. 3 Ma were consequences of that range uplift. Here, we present cosmogenic nuclide-derived (Be-10) paleodenudation rates from 6 to 2 Ma fluvial deposits collected from the Humahuaca Basin. Despite increased tectonic activity, our Be-10 data show a tenfold decrease in denudation rates at ca. 3 Ma, documenting a link between uplift-induced semiarid conditions and decreasing hillslope denudation rates. This new data set thus demonstrates the influence of hydrological change on spatiotemporal denudation patterns in tectonically active mountain areas.
Y1  - 2019
U6  - https://doi.org/10.1130/G45800.1
SN  - 0091-7613
SN  - 1943-2682
VL  - 47
IS  - 4
SP  - 359
EP  - 362
PB  - American Institute of Physics
CY  - Boulder
ER  - 
TY  - JOUR
A1  - Walter, J.
A1  - Lück, Erika
A1  - Heller, C.
A1  - Bauriegel, Albrecht
A1  - Zeitz, Jutta
T1  - Relationship between electrical conductivity and water content of peat and gyttja
BT  - implications for electrical surveys of drained peatlands
JF  - Near surface geophysics
N2  - The application of electrical resistivity tomography to peatlands supports conventional coring by providing data on the current condition of peatlands, including data on stratigraphy, peat properties and thickness of organic deposits. Data on the current condition of drained peatlands are particularly required to improve estimates of carbon storage as well as losses and emissions from agriculturally used peatlands. However, most of the studies focusing on electrical resistivity tomography surveys have been conducted on natural peatlands with higher groundwater levels. Peatlands drained for agriculture have not often been studied using geophysical techniques. Drained sites are characterized by low groundwater levels and high groundwater fluctuations during the year, which lead to varying levels of water saturation. To validate better electrical resistivity tomography surveys of drained peatlands, the aim of this laboratory study is to investigate the influence of varying water saturation levels on electrical conductivity (reciprocal of resistivity) for a variety of peat and gyttja types, as well as for different degrees of peat decomposition. Results show that different levels of water saturation strongly influence bulk electrical conductivity. Distinct differences in this relationship exist between peat and gyttja substrates and between different degrees of peat decomposition. Peat shows an exponential relationship for all degrees of decomposition, whereas gyttja, in particular organic-rich gyttja, is characterized by a rather unimodal relationship. The slopes for the relationship between electrical conductivity and water content are steeper at high degrees of decomposition than for peat of low degrees of decomposition. These results have direct implications for field electrical resistivity tomography surveys. In drained peatlands that are strongly susceptible to drying, electrical resistivity tomography surveys have a high potential to monitor the actual field water content. In addition, at comparable water saturations, high or low degrees of decomposition can be inferred from electrical conductivity.
KW  - Electrical conductivity
KW  - Peat
KW  - Gyttja
Y1  - 2019
U6  - https://doi.org/10.1002/nsg.12030
SN  - 1569-4445
SN  - 1873-0604
VL  - 17
IS  - 2
SP  - 169
EP  - 179
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Korup, Oliver
A1  - Seidemann, Jan
A1  - Mohr, Christian Heinrich
T1  - Increased landslide activity on forested hillslopes following two recent volcanic eruptions in Chile
JF  - Nature geoscience
N2  - Large explosive eruptions can bury landscapes beneath thick layers of tephra. Rivers subsequently overloaded with excess pyroclastic sediments have some of the highest reported specific sediment yields. Much less is known about how hillslopes respond to tephra loads. Here, we report a pulsed and distinctly delayed increase in landslide activity following the eruptions of the Chaiten (2008) and Puyehue-Cordon Caulle (2011) volcanoes in southern Chile. Remote-sensing data reveal that land-slides clustered in densely forested hillslopes mostly two to six years after being covered by tephra. This lagged instability is consistent with a gradual loss of shear strength of decaying tree roots in areas of high tephra loads. Surrounding areas with comparable topography, forest cover, rainfall and lithology maintained landslide rates roughly ten times lower. The landslides eroded the landscape by up to 4.8 mm on average within 30 km of both volcanoes, mobilizing up to 1.6 MtC at rates of about 265 tC km(-2) yr(-1). We suggest that these yields may reinforce the elevated river loads of sediment and organic carbon in the decade after the eruptions. We recommend that studies of post-eruptive mass fluxes and hazards include lagged landslide responses of tephra-covered forested hillslopes, to avoid substantial underestimates.
Y1  - 2019
U6  - https://doi.org/10.1038/s41561-019-0315-9
SN  - 1752-0894
SN  - 1752-0908
VL  - 12
IS  - 4
SP  - 284
EP  - 289
PB  - Nature Publ. Group
CY  - New York
ER  - 
TY  - JOUR
A1  - He, Zhihua
A1  - Unger-Shayesteh, Katy
A1  - Vorogushyn, Sergiy
A1  - Weise, Stephan M.
A1  - Kalashnikova, Olga
A1  - Gafurov, Abror
A1  - Duethmann, Doris
A1  - Barandun, Martina
A1  - Merz, Bruno
T1  - Constraining hydrological model parameters using water isotopic compositions in a glacierized basin, Central Asia
JF  - Journal of hydrology
N2  - Water stable isotope signatures can provide valuable insights into the catchment internal runoff processes. However, the ability of the water isotope data to constrain the internal apportionments of runoff components in hydrological models for glacierized basins is not well understood. This study developed an approach to simultaneously model the water stable isotopic compositions and runoff processes in a glacierized basin in Central Asia. The fractionation and mixing processes of water stable isotopes in and from the various water sources were integrated into a glacio-hydrological model. The model parameters were calibrated on discharge, snow cover and glacier mass balance data, and additionally isotopic composition of streamflow. We investigated the value of water isotopic compositions for the calibration of model parameters, in comparison to calibration methods without using such measurements. Results indicate that: (1) The proposed isotope-hydrological integrated modeling approach was able to reproduce the isotopic composition of streamflow, and improved the model performance in the evaluation period; (2) Involving water isotopic composition for model calibration reduced the model parameter uncertainty, and helped to reduce the uncertainty in the quantification of runoff components; (3) The isotope-hydrological integrated modeling approach quantified the contributions of runoff components comparably to a three-component tracer-based end-member mixing analysis method for summer peak flows, and required less water tracer data. Our findings demonstrate the value of water isotopic compositions to improve the quantification of runoff components using hydrological models in glacierized basins.
KW  - Water stable isotope
KW  - Isotope-hydrological integrated modeling
KW  - Quantification of runoff components
KW  - Glacierized basins
Y1  - 2019
U6  - https://doi.org/10.1016/j.jhydrol.2019.01.048
SN  - 0022-1694
SN  - 1879-2707
VL  - 571
SP  - 332
EP  - 348
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Angelopoulos, Michael
A1  - Westermann, Sebastian
A1  - Overduin, Pier Paul
A1  - Faguet, Alexey
A1  - Olenchenko, Vladimir
A1  - Grosse, Guido
A1  - Grigoriev, Mikhail N.
T1  - Heat and salt flow in subsea permafrost modeled with CryoGRID2
JF  - Journal of geophysical research : Earth surface
N2  - Thawing of subsea permafrost can impact offshore infrastructure, affect coastal erosion, and release permafrost organic matter. Thawing is usually modeled as the result of heat transfer, although salt diffusion may play an important role in marine settings. To better quantify nearshore subsea permafrost thawing, we applied the CryoGRID2 heat diffusion model and coupled it to a salt diffusion model. We simulated coastline retreat and subsea permafrost evolution as it develops through successive stages of a thawing sequence at the Bykovsky Peninsula, Siberia. Sensitivity analyses for seawater salinity were performed to compare the results for the Bykovsky Peninsula with those of typical Arctic seawater. For the Bykovsky Peninsula, the modeled ice-bearing permafrost table (IBPT) for ice-rich sand and an erosion rate of 0.25m/year was 16.7 m below the seabed 350m offshore. The model outputs were compared to the IBPT depth estimated from coastline retreat and electrical resistivity surveys perpendicular to and crossing the shoreline of the Bykovsky Peninsula. The interpreted geoelectric data suggest that the IBPT dipped to 15-20m below the seabed at 350m offshore. Both results suggest that cold saline water forms beneath grounded ice and floating sea ice in shallow water, causing cryotic benthic temperatures. The freezing point depression produced by salt diffusion can delay or prevent ice formation in the sediment and enhance the IBPT degradation rate. Therefore, salt diffusion may facilitate the release of greenhouse gasses to the atmosphere and considerably affect the design of offshore and coastal infrastructure in subsea permafrost areas.
KW  - subsea permafrost
KW  - salt diffusion
KW  - CryoGRID
KW  - Lena Delta
KW  - Bykovsky Peninsula
KW  - electrical resistivity
Y1  - 2019
U6  - https://doi.org/10.1029/2018JF004823
SN  - 2169-9003
SN  - 2169-9011
VL  - 124
IS  - 4
SP  - 920
EP  - 937
PB  - American Geophysical Union
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Javhar, Aminov
A1  - Chen, Xi
A1  - Bao, Anming
A1  - Jamshed, Aminov
A1  - Yunus, Mamadjanov
A1  - Jovid, Aminov
A1  - Latipa, Tuerhanjiang
T1  - Comparison of Multi-Resolution Optical Landsat-8, Sentinel-2 and Radar Sentinel-1 Data for Automatic Lineament Extraction
BT  - A Case Study of Alichur Area, SE Pamir
JF  - Remote sensing
N2  - Lineament mapping, which is an important part of any structural geological investigation, is made more efficient and easier by the availability of optical as well as radar remote sensing data, such as Landsat and Sentinel with medium and high spatial resolutions. However, the results from these multi-resolution data vary due to their difference in spatial resolution and sensitivity to soil occupation. The accuracy and quality of extracted lineaments depend strongly on the spatial resolution of the imagery. Therefore, the aim of this study was to compare the optical Landsat-8, Sentinel-2A, and radar Sentinel-1A satellite data for automatic lineament extraction. The framework of automatic approach includes defining the optimal parameters for automatic lineament extraction with a combination of edge detection and line-linking algorithms and determining suitable bands from optical data suited for lineament mapping in the study area. For the result validation, the extracted lineaments are compared against the manually obtained lineaments through the application of directional filtering and edge enhancement as well as to the lineaments digitized from the existing geological maps of the study area. In addition, a digital elevation model (DEM) has been utilized for an accuracy assessment followed by the field verification. The obtained results show that the best correlation between automatically extracted lineaments, manual interpretation, and the preexisting lineament map is achieved from the radar Sentinel-1A images. The tests indicate that the radar data used in this study, with 5872 and 5865 lineaments extracted from VH and VV polarizations respectively, is more efficient for structural lineament mapping than the Landsat-8 and Sentinel-2A optical imagery, from which 2338 and 4745 lineaments were extracted respectively.
KW  - image enhancement
KW  - automatic lineament extraction
KW  - Landsat-8
KW  - Sentinel-1
KW  - Sentinel-2
KW  - structural mapping
Y1  - 2019
U6  - https://doi.org/10.3390/rs11070778
SN  - 2072-4292
VL  - 11
IS  - 7
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Latimer, Andrew M.
A1  - Jacobs, Brooke S.
A1  - Gianoli, Ernesto
A1  - Heger, Tina
A1  - Salgado-Luarte, Cristian
T1  - Parallel functional differentiation of an invasive annual plant on two continents
JF  - AoB PLANTS
N2  - Rapid local adaptation frequently occurs during the spread of invading species. It remains unclear, however, how consistent, and therefore potentially predictable, such patterns of local adaptation are. One approach to this question is to measure patterns of local differentiation in functional traits and plasticity levels in invasive species in multiple regions. Finding consistent patterns of local differentiation in replicate regions suggests that these patterns are adaptive. Further, this outcome indicates that the invading species likely responds predictably to selection along environmental gradients, even though standing genetic variation is likely to have been reduced during introduction. We studied local differentiation in the invasive annual plant Erodium cicutarium in two invaded regions, California and Chile. We collected seeds from across strong gradients in precipitation and temperature in Mediterranean-climate parts of the two regions (10 populations per region). We grew seeds from maternal families from these populations through two generations and exposed the second generation to contrasting levels of water and nutrient availability. We measured growth, flowering time and leaf functional traits across these treatments to obtain trait means and plasticity measures. We found strong differentiation among populations in all traits. Plants from drier environments flowered earlier, were less plastic in flowering time and reached greater size in all treatments. Correlations among traits within regions suggested a coordinated evolutionary response along environmental gradients associated with growing season length. There was little divergence in traits and trait intercorrelations between regions, but strongly parallel divergence in traits within regions. Similar, statistically consistent patterns of local trait differentiation across two regions suggest that local adaptation to environmental gradients has aided the spread of this invasive species, and that the formation of ecotypes in newly invaded environments has been relatively consistent and predictable.
KW  - Erodium cicutarium
KW  - flowering time
KW  - functional trait correlations
KW  - invasive species
KW  - life-history strategy
KW  - local adaptation
KW  - parallel evolution
KW  - phenotypic plasticity
Y1  - 2019
U6  - https://doi.org/10.1093/aobpla/plz010
SN  - 2041-2851
VL  - 11
IS  - 2
PB  - Oxford University Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Araya Vargas, Jaime Andrés
A1  - Meqbel, Naser M.
A1  - Ritter, Oliver
A1  - Brasse, H.
A1  - Weckmann, Ute
A1  - Yanez, Gonzalo
A1  - Godoy, B.
T1  - Fluid Distribution in the Central Andes Subduction Zone Imaged With Magnetotellurics
JF  - Journal of geophysical research : Solid earth
N2  - We present a model of the electrical resistivity structure of the lithosphere in the Central Andes between 20 degrees and 24 degrees S from 3-D inversion of 56 long-period magnetotelluric sites. Our model shows a complex resistivity structure with significant variability parallel and perpendicular to the trench direction. The continental forearc is characterized mainly by high electrical resistivity (>1,000m), suggesting overall low volumes of fluids. However, low resistivity zones (LRZs, <5m) were found in the continental forearc below areas where major trench-parallel faults systems intersect NW-SE transverse faults. Forearc LRZs indicate circulation and accumulation of fluids in highly permeable fault zones. The continental crust along the arc shows three distinctive resistivity domains, which coincide with segmentation in the distribution of volcanoes. The northern domain (20 degrees-20.5 degrees S) is characterized by resistivities >1,000m and the absence of active volcanism, suggesting the presence of a low-permeability block in the continental crust. The central domain (20.5 degrees-23 degrees S) exhibits a number of LRZs at varying depths, indicating different levels of a magmatic plumbing system. The southern domain (23 degrees-24 degrees S) is characterized by resistivities >1,000m, suggesting the absence of large magma reservoirs below the volcanic chain at crustal depths. Magma reservoirs located below the base of the crust or in the backarc may fed active volcanism in the southern domain. In the subcontinental mantle, the model exhibits LRZs in the forearc mantle wedge and above clusters of intermediate-depth seismicity, likely related to fluids produced by serpentinization of the mantle and eclogitization of the slab, respectively.
KW  - Subduction Zone
KW  - Central Andes
KW  - Magnetotellurics
KW  - Seismotectonic segmentation
KW  - Fluid processes
Y1  - 2019
U6  - https://doi.org/10.1029/2018JB016933
SN  - 2169-9313
SN  - 2169-9356
VL  - 124
IS  - 4
SP  - 4017
EP  - 4034
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Soares, Gabriel
A1  - Yamazaki, Yosuke
A1  - Matzka, Jürgen
A1  - Pinheiro, Katia
A1  - Stolle, Claudia
A1  - Alken, Patrick
A1  - Yoshikawa, Akimasa
A1  - Uozumi, Teiji
A1  - Fujimoto, Akiko
A1  - Kulkarni, Atul
T1  - Longitudinal variability of the equatorial counter electrojet during the solar cycle 24
JF  - Studia geophysica et geodaetica
N2  - Ground and space-based geomagnetic data were used in the investigation of the longitudinal, seasonal and lunar phase dependence of the equatorial counter electrojet (CEJ) occurrence in the Peruvian, Brazilian, African, Indian and Philippine sectors during geomagnetically quiet days from the solar cycle 24 (2008 to 2018). We found that CEJ events occur more frequently during the morning (MCEJ) than in the afternoon (ACEJ). The highest MCEJ and ACEJ occurrence rates were observed for the Brazilian sector. Distinct seasonal dependence was found for each longitudinal sector under investigation. The lunar phase dependence was determined for the first time for the Philippine sector (longitude 125 degrees E), and it was shown to be less pronounced than in the Peruvian, Brazilian and African sectors. We demonstrate that differences in CEJ rates derived from ground-based and satellite data can arise from the longitudinal separation between low-latitude and equatorial stations that are used to determine the signal and its consequent time delay in their sunrise/sunset times at ionospheric heights.
KW  - geomagnetism
KW  - equatorial ionosphere
KW  - geomagnetic observatories
KW  - satellite data
Y1  - 2019
U6  - https://doi.org/10.1007/s11200-018-0286-0
SN  - 0039-3169
SN  - 1573-1626
VL  - 63
IS  - 2
SP  - 304
EP  - 319
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Zhu, Hui
A1  - Chen, Lunjin
A1  - Liu, Xu
A1  - Shprits, Yuri Y.
T1  - Modulation of locally generated equatorial noise by ULF wave
JF  - Journal of geophysical research : Space physics
N2  - In this paper we report a rare and fortunate event of fast magnetosonic (MS, also called equatorial noise) waves modulated by compressional ultralow frequency (ULF) waves measured by Van Allen Probes. The characteristics of MS waves, ULF waves, proton distribution, and their potential correlations are analyzed. The results show that ULF waves can modulate the energetic ring proton distribution and in turn modulate the MS generation. Furthermore, the variation of MS intensities is attributed to not only ULF wave activities but also the variation of background parameters, for example, number density. The results confirm the opinion that MS waves are generated by proton ring distribution and propose a new modulation phenomenon.
Y1  - 2019
U6  - https://doi.org/10.1029/2018JA026199
SN  - 2169-9380
SN  - 2169-9402
VL  - 124
IS  - 4
SP  - 2779
EP  - 2787
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Winter, Benjamin
A1  - Schneeberger, Klaus
A1  - Dung, N. V.
A1  - Huttenlau, M.
A1  - Achleitner, S.
A1  - Stötter, J.
A1  - Merz, Bruno
A1  - Vorogushyn, Sergiy
T1  - A continuous modelling approach for design flood estimation on sub-daily time scale
JF  - Hydrological sciences journal = Journal des sciences hydrologiques
N2  - Design flood estimation is an essential part of flood risk assessment. Commonly applied are flood frequency analyses and design storm approaches, while the derived flood frequency using continuous simulation has been getting more attention recently. In this study, a continuous hydrological modelling approach on an hourly time scale, driven by a multi-site weather generator in combination with a -nearest neighbour resampling procedure, based on the method of fragments, is applied. The derived 100-year flood estimates in 16 catchments in Vorarlberg (Austria) are compared to (a) the flood frequency analysis based on observed discharges, and (b) a design storm approach. Besides the peak flows, the corresponding runoff volumes are analysed. The spatial dependence structure of the synthetically generated flood peaks is validated against observations. It can be demonstrated that the continuous modelling approach can achieve plausible results and shows a large variability in runoff volume across the flood events.
KW  - derived flood frequency
KW  - continuous modelling
KW  - temporal disaggregation
KW  - flood hazard
KW  - synthetic flood events
Y1  - 2019
U6  - https://doi.org/10.1080/02626667.2019.1593419
SN  - 0262-6667
SN  - 2150-3435
VL  - 64
IS  - 5
SP  - 539
EP  - 554
PB  - Routledge, Taylor & Francis Group
CY  - Abingdon
ER  - 
TY  - JOUR
A1  - von Specht, Sebastian
A1  - Öztürk, Ugur
A1  - Veh, Georg
A1  - Cotton, Fabrice
A1  - Korup, Oliver
T1  - Effects of finite source rupture on landslide triggering
BT  - the 2016 M-w 7.1 Kumamoto earthquake
JF  - Solid earth
N2  - The propagation of a seismic rupture on a fault introduces spatial variations in the seismic wave field surrounding the fault. This directivity effect results in larger shaking amplitudes in the rupture propagation direction. Its seismic radiation pattern also causes amplitude variations between the strike-normal and strike-parallel components of horizontal ground motion. We investigated the landslide response to these effects during the 2016 Kumamoto earthquake (M-w 7.1) in central Kyushu (Japan). Although the distribution of some 1500 earthquake-triggered landslides as a function of rupture distance is consistent with the observed Arias intensity, the landslides were more concentrated to the northeast of the southwest-northeast striking rupture. We examined several landslide susceptibility factors: hillslope inclination, the median amplification factor (MAF) of ground shaking, lithology, land cover, and topographic wetness. None of these factors sufficiently explains the landslide distribution or orientation (aspect), although the landslide head scarps have an elevated hillslope inclination and MAF. We propose a new physics-based ground-motion model (GMM) that accounts for the seismic rupture effects, and we demonstrate that the low-frequency seismic radiation pattern is consistent with the overall landslide distribution. Its spatial pattern is influenced by the rupture directivity effect, whereas landslide aspect is influenced by amplitude variations between the fault-normal and fault-parallel motion at frequencies < 2 Hz. This azimuth dependence implies that comparable landslide concentrations can occur at different distances from the rupture. This quantitative link between the prevalent landslide aspect and the low-frequency seismic radiation pattern can improve coseismic landslide hazard assessment.
Y1  - 2019
U6  - https://doi.org/10.5194/se-10-463-2019
SN  - 1869-9510
SN  - 1869-9529
VL  - 10
IS  - 2
SP  - 463
EP  - 486
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Petersen, Gesa Maria
A1  - Cesca, Simone
A1  - Kriegerowski, Marius
T1  - Automated quality control for large seismic networks
BT  - implementation and application to the AlpArray seismic network
JF  - Seismological research letters
N2  - As a consequence of the rapid growing worldwide seismic data set, a huge variety of automatized data-processing methods have been developed. To perform automatized waveform-based seismological studies aiming for magnitudes or source process inversion, it is crucial to identify network stations with erroneous transfer functions, gain factors, or component orientations. We developed a new tool dedicated to automated station quality control of dense seismic networks and arrays. The python-based AutoStatsQ toolbox uses the pyrocko seismic data-processing environment. The toolbox automatically downloads data and metadata for selected teleseismic events and performs different tests. As a result, relative gain factors, sensor orientation corrections, and reliable frequency bands are computed for all stations in a chosen time period. Relative gain factors are calculated for all stations and events in a time domain based on maximum P-phase amplitudes. A Rayleigh-wave polarization analysis is used to identify deviating sensor orientations. The power spectra of all stations in a given frequency range are compared with synthetic ones, accessing Global Centroid Moment Tensor (CMT) solutions. Frequency ranges of coinciding synthetic and recorded power spectral densities (PSDs) may serve as guidelines for choosing band-pass filters for moment tensor (MT) inversion and help confirm the corner frequency of the instrument. The toolbox was applied to the permanent and temporary AlpArray networks as well as to the denser SWATH-D network, a total of over 750 stations. Stations with significantly deviating gain factors were identified, as well as stations with inverse polarity and misorientations of the horizontal components. The tool can be used to quickly access network quality and to omit or correct stations before MT inversion. Electronic Supplement: List of teleseismic events and tables of median, mean, and standard deviation of relative gain factors, and figures of relative gain factors of all event-station pairs, waveform example showing inverse polarity of horizontal components on ZS.D125, histograms of median, mean, and standard deviation of the correction angles, examples of synthetic and recorded frequency spectra of ZS.D046 and NI.VINO.
Y1  - 2019
U6  - https://doi.org/10.1785/0220180342
SN  - 0895-0695
SN  - 1938-2057
VL  - 90
IS  - 3
SP  - 1177
EP  - 1190
PB  - Seismological Society of America
CY  - Albany
ER  - 
TY  - JOUR
A1  - Veh, Georg
A1  - Korup, Oliver
A1  - von Specht, Sebastian
A1  - Rößner, Sigrid
A1  - Walz, Ariane
T1  - Unchanged frequency of moraine-dammed glacial lake outburst floods in the Himalaya
JF  - Nature climate change
N2  - Shrinking glaciers in the Hindu Kush-Karakoram-Himalaya-Nyainqentanglha (HKKHN) region have formed several thousand moraine-dammed glacial lakes(1-3), some of these having grown rapidly in past decades(3,4). This growth may promote more frequent and potentially destructive glacial lake outburst floods (GLOFs)(5-7). Testing this hypothesis, however, is confounded by incomplete databases of the few reliable, though selective, case studies. Here we present a consistent Himalayan GLOF inventory derived automatically from all available Landsat imagery since the late 1980s. We more than double the known GLOF count and identify the southern Himalayas as a hotspot region, compared to the more rarely affected Hindu Kush-Karakoram ranges. Nevertheless, the average annual frequency of 1.3 GLOFs has no credible posterior trend despite reported increases in glacial lake areas in most of the HKKHN3,8, so that GLOF activity per unit lake area has decreased since the late 1980s. We conclude that learning more about the frequency and magnitude of outburst triggers, rather than focusing solely on rapidly growing glacial lakes, might improve the appraisal of GLOF hazards.
KW  - Climate change
KW  - Cryospheric science
KW  - Environmental impact
KW  - Geomorphology
Y1  - 2019
U6  - https://doi.org/10.1038/s41558-019-0437-5
SN  - 1758-678X
SN  - 1758-6798
VL  - 9
IS  - 5
SP  - 379
EP  - 383
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Merz, Christoph
A1  - Lischeid, Gunnar
T1  - Multivariate analysis to assess the impact of irrigation on groundwater quality
JF  - Environmental earth sciences
N2  - Due to increasing demands for irrigation using groundwater as a source there is an urgent need for efficient methods that shed light on the resulting anthropogenic impacts on the connected aquifers. Thus an innovative approach is introduced, that aims to identify predominant geochemical changes in the groundwater system. The approach involves a principal component analysis as a promising tool to disentangle the effects of different impacts and even to give a quantitative assessment of the respective effect strength at each site. The study was applied in an irrigation region of the Nuthe River Basin, State Brandenburg, Northeast Germany. The results identify the negative impacts on the groundwater quality in the aquifer used for irrigation. A decrease of shallow groundwater quality under irrigation due to contamination with fertilizers (NO3, Cl, K, Na) and a slight shift in the redox system is indicated. Beside this direct impact on the shallow groundwater a long-term impact on a deeper groundwater resource could be identified. There is clear evidence, that the contamination is not restricted to the shallow groundwater but that extraction from deeper wells increasingly includes deeper, uncontaminated groundwater resources into the local irrigation cycle. The approach can be used as a basic tool for the adaptation of sustainable agricultural irrigation management strategies.
KW  - Irrigation
KW  - Groundwater quality
KW  - Principal component analysis
Y1  - 2019
U6  - https://doi.org/10.1007/s12665-019-8274-4
SN  - 1866-6280
SN  - 1866-6299
VL  - 78
IS  - 274
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Kaufmann, Felix E. D.
A1  - Hoffmann, Marie C.
A1  - Bachmann, Kai
A1  - Veksler, Ilya V.
A1  - Trumbull, Robert B.
A1  - Hecht, Lutz
T1  - Variations in Composition, Texture, and Platinum Group Element Mineralization in the Lower Group and Middle Group Chromitites of the Northwestern Bushveld Complex, South Africa
JF  - Economic geology
N2  - Small-scale variations in mineral chemistry, textures, and platinum group element (PGE) mineralization were investigated in the Lower and Middle Group chromitite layers LG6, LG6a, MG1, MG2, and MG2 II from vertical drill core profiles at the Thaba mine in the northwestern limb of the Bushveld Complex. We present detailed geochemical profiles of chromite composition and chromite crystal size distribution curves to shed light on the processes of chromite accumulation and textural modification as well as mineralization. Multiple samples within each layer were assayed for PGE concentrations, and the respective platinum group mineral association was determined by mineral liberation analysis (MLA). There is strong evidence for postcumulus changes in the chromitites. The crystal size distribution curves suggest that the primary chromite texture was coarsened by a combination of adcumulus growth and textural equilibration, while compaction of the crystal mush played only a minor role. Mineral compositions were also modified by postcumulus processes, but because of the very high modal amount of chromite and its local preservation in orthopyroxene oikocrysts, that phase retained much primary information. Vertical variations of chromite composition within chromitite layers and from one layer to another do not support the idea of chromite accumulation from crystal-rich slurries or crystal settling from a large magma chamber. Instead, we favor a successive buildup of chromitite layers by repeated injections of relatively thin layers of chromite-saturated magmas, with in situ crystallization occurring at the crystal mush-magma interface. The adcumulus growth of chromite grains to form massive chromitite required addition of Cr to the layers, which we attribute to downward percolation from the overlying magma. The PGE concentrations are elevated in all chromitite layers compared to adjacent silicate rocks and show a systematic increase upward from LG6 (avg 807 ppb Ir + Ru + Rh + Pt + Pd + Au) to MG2 II (avg 2,062 ppb). There are also significant internal variations in all layers, with enrichments at hanging and/or footwalls. The enriched nature of chromitites in PGEs compared to host pyroxenites is a general feature, independent of the layer thickness. The MLA results distinguish two principal groups of PGE mineral associations: the LG6, LG6, and MG1 are dominated by the malanite series, laurite, and PGE sulfarsenides, while the MG2 and MG2 II layers are characterized by laurite and PGE sulfides as well as Pt-Fe-Sn and PGE-Sb-Bi-Pb alloys. Differences in the PGE associations are attributed to postcumulus alteration of the MG2 and MG2 II layer, while the chromitites below, particularly LG6 and LG6a, contain a more pristine association.
Y1  - 2019
U6  - https://doi.org/10.5382/econgeo.4641
SN  - 0361-0128
SN  - 1554-0774
VL  - 114
IS  - 3
SP  - 569
EP  - 590
PB  - The Economic Geology Publ. Co
CY  - Littleton
ER  - 
TY  - JOUR
A1  - Kwiatek, Grzegorz
A1  - Saarno, Tero
A1  - Ader, Thomas
A1  - Blümle, Felix
A1  - Bohnhoff, Marco
A1  - Chendorain, Michael
A1  - Dresen, Georg
A1  - Heikkinen, Pekka
A1  - Kukkonen, Ilmo
A1  - Leary, Peter
A1  - Leonhardt, Maria
A1  - Malin, Peter
A1  - Martinez-Garzon, Patricia
A1  - Passmore, Kevin
A1  - Passmore, Paul
A1  - Valenzuela, Sergio
A1  - Wollin, Christopher
T1  - Controlling fluid-induced seismicity during a 6.1-km-deep geothermal stimulation in Finland
JF  - Science Advances
N2  - We show that near-real-time seismic monitoring of fluid injection allowed control of induced earthquakes during the stimulation of a 6.1-km-deep geothermal well near Helsinki, Finland. A total of 18,160 m(3) of fresh water was pumped into crystalline rocks over 49 days in June to July 2018. Seismic monitoring was performed with a 24-station borehole seismometer network. Using near-real-time information on induced-earthquake rates, locations, magnitudes, and evolution of seismic and hydraulic energy, pumping was either stopped or varied-in the latter case, between well-head pressures of 60 and 90 MPa and flow rates of 400 and 800 liters/min. This procedure avoided the nucleation of a project-stopping magnitude M-W 2.0 induced earthquake, a limit set by local authorities. Our results suggest a possible physics-based approach to controlling stimulation-induced seismicity in geothermal projects.
Y1  - 2019
U6  - https://doi.org/10.1126/sciadv.aav7224
SN  - 2375-2548
VL  - 5
IS  - 5
PB  - American Association for the Advancement of Science
CY  - Washington
ER  - 
TY  - JOUR
A1  - Hofmann, Hannes
A1  - Zimmermann, Günter
A1  - Farkas, Márton Pál
A1  - Huenges, Ernst
A1  - Zang, Arno
A1  - Leonhardt, Maria
A1  - Kwiatek, Grzegorz
A1  - Martinez-Garzon, Patricia
A1  - Bohnhoff, Marco
A1  - Min, Ki-Bok
A1  - Fokker, Peter
A1  - Westaway, Rob
A1  - Bethmann, Falko
A1  - Meier, Peter
A1  - Yoon, Kern Shin
A1  - Choi, JaiWon
A1  - Lee, Tae Jong
A1  - Kim, Kwang Yeom
T1  - First field application of cyclic soft stimulation at the Pohang Enhanced Geothermal System site in Korea
JF  - Geophysical journal international
N2  - Large-magnitude fluid-injection induced seismic events are a potential risk for geothermal energy developments worldwide. One potential risk mitigation measure is the application of cyclic injection schemes. After validation at small (laboratory) and meso (mine) scale, the concept has now been applied for the first time at field scale at the Pohang Enhanced Geothermal System (EGS) site in Korea. From 7 August until 14 August 2017 a total of 1756 m(3) of surface water was injected into Pohang well PX-1 at flow rates between 1 and 10 l s(-1), with a maximum wellhead pressure (WHP) of 22.8 MPa, according to a site-specific cyclic soft stimulation schedule and traffic light system. A total of 52 induced microearthquakes were detected in real-time during and shortly after the injection, the largest of M-w 1.9. After that event a total of 1771 m(3) of water was produced back from the well over roughly 1 month, during which time no larger-magnitude seismic event was observed. The hydraulic data set exhibits pressure-dependent injectivity increase with fracture opening between 15 and 17 MPa WHP, but no significant permanent transmissivity increase was observed. The maximum magnitude of the induced seismicity during the stimulation period was below the target threshold of M-w 2.0 and additional knowledge about the stimulated reservoir was gained. Additionally, the technical feasibility of cyclic injection at field scale was evaluated. The major factors that limited the maximum earthquake magnitude are believed to be: limiting the injected net fluid volume, flowback after the occurrence of the largest induced seismic event, using a cyclic injection scheme, the application of a traffic light system, and including a priori information from previous investigations and operations in the treatment design.
KW  - Cyclic soft stimulation (CSS)
KW  - induced seismicity
KW  - risk mitigation
KW  - enhanced geothermal systems (EGS)
KW  - granite
KW  - Pohang (Korea)
Y1  - 2019
U6  - https://doi.org/10.1093/gji/ggz058
SN  - 0956-540X
SN  - 1365-246X
VL  - 217
IS  - 2
SP  - 926
EP  - 949
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Nguyen, Minh N.
A1  - Meharg, Andy A.
A1  - Carey, Manus
A1  - Dultz, Stefan
A1  - Marone, Federica
A1  - Cichy, Sarah Bettina
A1  - Tran, Chinh T.
A1  - Le, Giang H.
A1  - Mai, Nga T.
A1  - Nguyen, Thinh T. H.
T1  - Fern, Dicranopteris linearis, derived phytoliths in soil
BT  - Morphotypes, solubility and content in relation to soil properties
JF  - European journal of soil science
N2  - Ferns are among the most popular groups of plants in the tropics and subtropics, and their role as carbon sequestrators has been widely recognized. However, there is little understanding of the silicaceous structures (phytoliths) of ferns, rate of phytolith turnover, the consequences for organic matter sequestered in phytoliths and consequences for other soil properties. In the study reported here, high-resolution X-ray tomographic microscopy and chemical characterization were applied to examine the traits of phytoliths of the fern Dicranopteris linearis (Burm.f.) Underw. (D. linearis), with a focus on their dissolution properties and accumulation in northern Vietnamese soils in relation to soil properties. Tomographic images revealed an inter-embedding structure of silica and organic matter, especially in leaf-derived material. We propose that organic matter and silica can preserve each other against decomposition. In batch experiments, there was a relatively small rate of dissolution of phytoliths with dry ashing and subsequent H2O2 treatment. Silicon (Si) dissolution for D. linearis phytolith samples was much less than that for rice phytoliths. Despite the fact that the aluminum (Al) content was large in D. linearis leaves, batch dissolution data did not confirm a relation between Al and the slow rate of phytolith dissolution. The soil phytolith content varied from 0.9 to 7.5 g kg(-1) in the topsoil across the mountainous areas in northern Vietnam, whereas it tended to be smaller in the subsoil. The data indicate a relation between phytolith and soil organic matter, clay content, oxalate-soluble Al and electrical conductivity, suggesting that these soil properties are among the important factors affecting the size of the soil phytolith Si pool. Highlights
KW  - accumulation in soils
KW  - dissolution properties
KW  - phytolith
KW  - silicon
Y1  - 2019
U6  - https://doi.org/10.1111/ejss.12754
SN  - 1351-0754
SN  - 1365-2389
VL  - 70
IS  - 3
SP  - 507
EP  - 517
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Asgarimehr, Milad
A1  - Wickert, Jens
A1  - Reich, Sebastian
T1  - Evaluating impact of rain attenuation on space-borne GNSS reflectometry wind speeds
JF  - Remote Sensing
N2  - The novel space-borne Global Navigation Satellite System Reflectometry (GNSS-R) technique has recently shown promise in monitoring the ocean state and surface wind speed with high spatial coverage and unprecedented sampling rate. The L-band signals of GNSS are structurally able to provide a higher quality of observations from areas covered by dense clouds and under intense precipitation, compared to those signals at higher frequencies from conventional ocean scatterometers. As a result, studying the inner core of cyclones and improvement of severe weather forecasting and cyclone tracking have turned into the main objectives of GNSS-R satellite missions such as Cyclone Global Navigation Satellite System (CYGNSS). Nevertheless, the rain attenuation impact on GNSS-R wind speed products is not yet well documented. Evaluating the rain attenuation effects on this technique is significant since a small change in the GNSS-R can potentially cause a considerable bias in the resultant wind products at intense wind speeds. Based on both empirical evidence and theory, wind speed is inversely proportional to derived bistatic radar cross section with a natural logarithmic relation, which introduces high condition numbers (similar to ill-posed conditions) at the inversions to high wind speeds. This paper presents an evaluation of the rain signal attenuation impact on the bistatic radar cross section and the derived wind speed. This study is conducted simulating GNSS-R delay-Doppler maps at different rain rates and reflection geometries, considering that an empirical data analysis at extreme wind intensities and rain rates is impossible due to the insufficient number of observations from these severe conditions. Finally, the study demonstrates that at a wind speed of 30 m/s and incidence angle of 30 degrees, rain at rates of 10, 15, and 20 mm/h might cause overestimation as large as approximate to 0.65 m/s (2%), 1.00 m/s (3%), and 1.3 m/s (4%), respectively, which are still smaller than the CYGNSS required uncertainty threshold. The simulations are conducted in a pessimistic condition (severe continuous rainfall below the freezing height and over the entire glistening zone) and the bias is expected to be smaller in size in real environments.
KW  - GNSS Reflectometry
KW  - wind speed
KW  - rain effect
KW  - rain attenuation
KW  - DDM simulation
Y1  - 2019
U6  - https://doi.org/10.3390/rs11091048
SN  - 2072-4292
VL  - 11
IS  - 9
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Luo, Xiaomin
A1  - Xiong, Chao
A1  - Gu, Shengfeng
A1  - Lou, Yidong
A1  - Stolle, Claudia
A1  - Wan, Xin
A1  - Liu, Kangkang
A1  - Song, Weiwei
T1  - Geomagnetically conjugate observations of equatorial plasma irregularities from swarm constellation and ground-based GPS stations
JF  - Journal of geophysical research: Space physics
N2  - The near-polar orbit satellites of Swarm mission provide a good opportunity to investigate the conjugacy of equatorial plasma irregularities (EPIs) since their trajectories at low latitudes are basically aligned with fixed geographical longitude. However, the Swarm in situ electron density occasionally shows EPIs at only one hemisphere at this longitude. In this study, we provide detailed analysis of such EPI events from the in situ electron densities and onboard global positioning system (GPS) measurements of Swarm low pair satellites, and simultaneous GPS data from two geomagnetically conjugate ground stations at the Africa longitudes. The result indicates that when Swam in situ electron density sometime shows EPIs at only one hemisphere, the GPS scintillations are still observed from the Swarm onboard receiver and by the two conjugate ground stations. It implies that the EPIs should generally elongate along the geomagnetic flux tube. More than two-year statistic results show that the onset time of scintillation in the northern station is on average 16 and 18 min earlier than that in the southern station for September equinox and December solstice in 2015, while for March equinox in 2016 the onset time of scintillation of northern station is about 11 min later than that of southern station, which indicates the asymmetry features of EPIs along the flux tube. Further analysis of nearly three-year GPS data from two conjugate stations at the Asia longitudes, we find that during solar maximum years the local sunset time plays an important role for causing the difference of onset time of scintillation between two conjugate stations.
Y1  - 2019
U6  - https://doi.org/10.1029/2019JA026515
SN  - 2169-9380
SN  - 2169-9402
VL  - 124
IS  - 5
SP  - 3650
EP  - 3665
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Dielforder, Armin
A1  - Frasca, Gianluca
A1  - Brune, Sascha
A1  - Ford, Mary
T1  - Formation of the Iberian-European convergent plate boundary fault and its effect on intraplate deformation in Central Europe
JF  - Geochemistry, geophysics, geosystems
N2  - With the Late Cretaceous onset of Africa-Iberia-Europe convergence Central Europe experienced a pulse of intraplate shortening lasting some 15-20 Myr. This deformation event documents area-wide deviatoric compression of Europe and has been interpreted as a far-field response to Africa-Iberia-Europe convergence. However, the factors that governed the compression of Europe and conditioned the transient character of the deformation event have remained unclear. Based on mechanical considerations, numerical simulations, and geological reconstructions, we examine how the dynamics of intraplate deformation were governed by the formation of a convergent plate boundary fault between Iberia and Europe. During the Late Cretaceous, plate convergence was accommodated by the inversion of a young hyperextended rift system separating Iberia from Europe. Our analysis shows that the strength of the lithosphere beneath this rift was initially sufficient to transmit large compressive stresses far into Europe, though the lithosphere beneath the rift was thinned and thermally weakened. Continued convergence forced the formation of the plate boundary fault between Iberia and Europe. The fault evolved progressively and constituted a lithospheric-scale structure at the southern margin of Europe that weakened rheologically. This development caused a decrease in mechanical coupling between Iberia and Europe and a reduction of compressional far field stresses, which eventually terminated intraplate deformation in Central Europe. Taken together, our findings suggest that the Late Cretaceous intraplate deformation event records a high force transient that relates to the earliest strength evolution of a lithospheric-scale plate boundary fault.
KW  - intraplate deformation
KW  - orogeny
KW  - plate boundary fault
KW  - plate coupling force
KW  - Pyrenees
KW  - lithosphere dynamics
Y1  - 2019
U6  - https://doi.org/10.1029/2018GC007840
SN  - 1525-2027
VL  - 20
IS  - 5
SP  - 2395
EP  - 2417
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Zhang, Peng
A1  - Najman, Yani
A1  - Mei, Lianfu
A1  - Millar, Ian
A1  - Sobel, Edward
A1  - Carter, Andrew
A1  - Barfod, Dan
A1  - Dhuime, Bruno
A1  - Garzanti, Eduardo
A1  - Govin, Gwladys
A1  - Vezzoli, Giovanni
A1  - Hu, Xiaolin
T1  - Palaeodrainage evolution of the large rivers of East Asia, and Himalayan-Tibet tectonics
JF  - Earth science reviews
N2  - A number of sedimentary provenance studies have been undertaken in order to determine whether the palaeo-Red River was once a river of continental proportions into which the upper reaches of the Yangtze, Salween, Mekong, Irrawaddy, and Yarlung drained. We have assessed the evidence that the Yarlung originally flowed into the palaeo-Red river, and then sequentially into the Irrawaddy and Brahmaputra, connecting to the latter first via the Lohit and then the Siang. For this river system, we have integrated our new data from the Paleogene-Recent Irrawaddy drainage basin (detrital zircon U-Pb with Hf and fission track, rutile U-Pb, mica Ar-Ar, bulk rock Sr-Nd, and petrography) with previously published data, to produce a palaeodrainage model that is consistent with all datasets. In our model, the Yarlung never flowed into the Irrawaddy drainage: during the Paleogene, the Yarlung suture zone was an internally drained basin, and from Neogene times onwards the Yarlung drained into the Brahmaputra in the Bengal Basin. The Central Myanmar Basin, through which the Irrawaddy River flows today, received predominantly locally-derived detritus until the Middle Eocene, the Irrawaddy initiated as a through-going river draining the Mogok Metamorphic Belt and Bomi-Chayu granites to the north sometime in the Late Eocene to Early Oligocene, and the river was dominated by a stable MMB-dominated drainage throughout the Neogene to present day. Existing evidence does not support any connection between the Yarlung and the Red River in the past, but there is a paucity of suitable palaeo-Red River deposits with which to make a robust comparison. We argue that this limitation also precludes a robust assessment of a palaeo-connection between the Yangtze/ Salween/Mekong and the Red River; it is difficult to unequivocally interpret the recorded provenance changes as the result of specific drainage reorganisations. We highlight the palaeo-Red River deposits of the Hanoi Basin as a potential location for future research focus in view of the near-complete Cenozoic record of palaeo-Red River deposits at this location. A majority of previous studies consider that if a major continental-scale drainage ever existed at all, it fragmented early in the Cenozoic. Such a viewpoint would agree with the growing body of evidence from palaeoaltitude studies that large parts of SE Tibet were uplifted by this period. This then leads towards the intriguing question as to the mechanisms which caused the major period of river incision in the Miocene in this region.
KW  - Eastern Tibet
KW  - Palaeodrainage
KW  - Red River
KW  - Irrawaddy River
KW  - Yarlung Tsangpo
KW  - Central Myanmar Basin
Y1  - 2019
U6  - https://doi.org/10.1016/j.earscirev.2019.02.003
SN  - 0012-8252
SN  - 1872-6828
VL  - 192
SP  - 601
EP  - 630
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Nazarova, Larisa B.
A1  - Razjigaeva, N. G.
A1  - Diekmann, Bernhard
A1  - Grebennikova, T. A.
A1  - Ganzey, L. A.
A1  - Belyanina, N. I.
A1  - Arslanov, K. A.
A1  - Kaistrenko, V. M.
A1  - Gorbunov, A. O.
A1  - Kharlamov, A. A.
A1  - Golovatyuk, L. V.
A1  - Syrykh, Lydmila S.
A1  - Subetto, D. A.
A1  - Lisitsyn, A. P.
T1  - Reconstruction of Holocene Environmental Changes in North-Western Pacific in Relation to Paleorecord from Shikotan Island
JF  - Doklady earth sciences
N2  - Results of a paleolimnological investigation of a well-dated lake sediment section from Shikotan Island (Southern Kurils) showed that from ca 8.0 to 5.8 cal ka BP a warm and humid period corresponding to middle Holocene optimum took place. Cooling thereafter corresponds to Neoglacial. A reconstructed from ca 0.9 to ca 0.58 cal ka BP warm period can correspond to a Medieval Warm Period. Cooling after 0.58cal ka BP can be correlated with the LIA. Marine regression stages were identified at ca 6.2-5.9, 5.5-5.1 and 1.07-0.36 cal ka BP. The general chronology of major climatic events of Holocene in the island is in accordance with the climate records from the North Pacific region. Revealed spatial differences in timing and magnitude of the Late Holocene climatic episodes (LIA, MWP) in the region needs further investigations.
Y1  - 2019
U6  - https://doi.org/10.1134/S1028334X19050143
SN  - 1028-334X
SN  - 1531-8354
VL  - 486
IS  - 1
SP  - 494
EP  - 497
PB  - Pleiades Publ.
CY  - New York
ER  - 
TY  - JOUR
A1  - Zorn, Edgar Ulrich
A1  - Le Corvec, Nicolas
A1  - Varley, Nick R.
A1  - Salzer, Jacqueline T.
A1  - Walter, Thomas R.
A1  - Navarro-Ochoa, Carlos
A1  - Vargas-Bracamontes, Dulce M.
A1  - Thiele, Samuel T.
A1  - Arámbula Mendoza, Raúl
T1  - Load stress controls on directional lava dome growth at Volcan de Colima, Mexico
JF  - Frontiers in Earth Science
N2  - During eruptive activity of andesitic stratovolcanoes, the extrusion of lava domes, their collapse and intermittent explosions are common volcanic hazards. Many lava domes grow in a preferred direction, in turn affecting the direction of lava flows and pyroclastic density currents. Access to active lava domes is difficult and hazardous, so detailed data characterizing lava dome growth are typically limited, keeping the processes controlling the directionality of extrusions unclear. Here we combine TerraSAR-X satellite radar observations with high-resolution airborne photogrammetry to assess morphological changes, and perform finite element modeling to investigate the impact of loading stress on shallow magma ascent directions associated with lava dome extrusion and crater formation at Volcan de Colima, Mexico. The TerraSAR-X data, acquired in similar to 1-m resolution spotlight mode, enable us to derive a chronology of the eruptive processes from intensity-based time-lapse observations of the general crater and dome evolution. The satellite images are complemented by close-range airborne photos, processed by the Structure-from-Motion workflow. This allows the derivation of high-resolution digital elevation models, providing insight into detailed loading and unloading features. During the observation period from Jan-2013 to Feb-2016, we identify a dominantly W-directed dome growth and lava flow production until Jan-2015. In Feb-2015, following the removal of the active summit dome, the surface crater widened and elongated along a NE-SW axis. Later in May-2015, a new dome grew toward the SW of the crater while a separate vent developed in the NE of the crater, reflecting a change in the direction of magma ascent and possible conduit bifurcation. Finite element models show a significant stress change in agreement with the observed magma ascent direction changes in response to the changing surface loads, both for loading (dome growth) and unloading (crater forming excavation) cases. These results allow insight into shallow dome growth dynamics and the migration of magma ascent in response to changing volcano summit morphology. They further highlight the importance of detailed volcano summit morphology surveillance, as changes in direction or location of dome extrusion may have major implications regarding the directions of potential volcanic hazards, such as pyroclastic density currents generated by dome collapse.
KW  - lava dome
KW  - load stress
KW  - Volcan de Colima
KW  - TerraSAR-X
KW  - photogrammetry
KW  - finite element modeling
Y1  - 2019
U6  - https://doi.org/10.3389/feart.2019.00084
SN  - 2296-6463
VL  - 7
PB  - Frontiers Media
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Fuchs, Matthias
A1  - Lenz, Josefine
A1  - Jock, Suzanne
A1  - Nitze, Ingmar
A1  - Jones, Benjamin M.
A1  - Strauss, Jens
A1  - Günther, Frank
A1  - Grosse, Guido
T1  - Organic carbon and nitrogen stocks along a thermokarst lake sequence in Arctic Alaska
JF  - Journal of geophysical research : Biogeosciences
N2  - Thermokarst lake landscapes are permafrost regions, which are prone to rapid (on seasonal to decadal time scales) changes, affecting carbon and nitrogen cycles. However, there is a high degree of uncertainty related to the balance between carbon and nitrogen cycling and storage. We collected 12 permafrost soil cores from six drained thermokarst lake basins (DTLBs) along a chronosequence north of Teshekpuk Lake in northern Alaska and analyzed them for carbon and nitrogen contents. For comparison, we included three lacustrine cores from an adjacent thermokarst lake and one soil core from a non thermokarst affected remnant upland. This allowed to calculate the carbon and nitrogen stocks of the three primary landscape units (DTLB, lake, and upland), to reconstruct the landscape history, and to analyze the effect of thermokarst lake formation and drainage on carbon and nitrogen stocks. We show that carbon and nitrogen contents and the carbon-nitrogen ratio are considerably lower in sediments of extant lakes than in the DTLB or upland cores indicating degradation of carbon during thermokarst lake formation. However, we found similar amounts of total carbon and nitrogen stocks due to the higher density of lacustrine sediments caused by the lack of ground ice compared to DTLB sediments. In addition, the radiocarbon-based landscape chronology for the past 7,000years reveals five successive lake stages of partially, spatially overlapping DTLBs in the study region, reflecting the dynamic nature of ice-rich permafrost deposits. With this study, we highlight the importance to include these dynamic landscapes in future permafrost carbon feedback models. Plain Language Summary When permanently frozen soils (permafrost) contain ice-rich sediments, the thawing of this permafrost causes the surface to sink, which may result in lake formation. This process, the thaw of ice-rich permafrost and melting of ground ice leads to characteristic landforms-known as thermokarst. Once such a thaw process is initiated in ice-rich sediments, a thaw lake forms and grows by shoreline erosion, eventually expanding until a drainage pathway is encountered and the lake eventually drains, resulting in a drained thermokarst lake basin. In our study, we show that such a thermokarst-affected landscape north of Teshekpuk Lake in northern Alaska is shaped by repeated thaw lake formation and lake drainage events during the past 7,000years, highlighting the dynamic nature of these landscapes. These landscape-scale processes have a big effect on the carbon and nitrogen stored in permafrost soils. We show that large amounts of carbon (>45kg C/m(2)) and nitrogen (>2.6kg N/m(2)) are stored in unfrozen lake sediments and in frozen soil sediments. The findings are important when considering the potential effect that permafrost thaw has for the global climate through releasing carbon and nitrogen, which was frozen and therefore locked away for millennia, from the active carbon cycle.
Y1  - 2019
U6  - https://doi.org/10.1029/2018JG004591
SN  - 2169-8953
SN  - 2169-8961
VL  - 124
IS  - 5
SP  - 1230
EP  - 1247
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Pilz, Marco
A1  - Cotton, Fabrice
T1  - Does the One-Dimensional Assumption Hold for Site Response Analysis?
BT  - A Study of Seismic Site Responses and Implication for Ground Motion Assessment Using KiK-Net Strong-Motion Data
JF  - Earthquake spectra : the professional journal of the Earthquake Engineering Research Institute
N2  - The one-dimensional (1-D) approach is still the dominant method to incorporate site effects in engineering applications. To bridge the 1-D to multidimensional site response analysis, we develop quantitative criteria and a reproducible method to identify KiK-net sites with significant deviations from 1-D behavior. We found that 158 out of 354 show two-dimensional (2-D) and three-dimensional (3-D) effects, extending the resonance toward shorter periods at which 2-D or 3-D site effects exceed those of the classic 1-D configurations and imposing an additional amplification to that caused by the impedance contrast alone. Such 2-D and 3-D effects go along with a large within-station ground motion variability. Remarkably, these effects are found to be more pronounced for small impedance contrasts. While it is hardly possible to identify common features in ground motion behavior for stations with similar topography typologies, it is not over-conservative to apply a safety factor to account for 2-D and 3-D site effects in ground motion modeling.
Y1  - 2019
U6  - https://doi.org/10.1193/050718EQS113M
SN  - 8755-2930
SN  - 1944-8201
VL  - 35
IS  - 2
SP  - 883
EP  - 905
PB  - Earthquake Engineering Research Institute
CY  - Oakland
ER  - 
TY  - JOUR
A1  - Fortesa, Josep
A1  - García-Comendador, Julian
A1  - Calsamiglia, A.
A1  - López-Tarazón, José Andrés
A1  - Latron, J.
A1  - Alorda, B.
A1  - Estrany, Joan
T1  - Comparison of stage/discharge rating curves derived from different recording systems
BT  - Consequences for streamflow data and water management in a Mediterranean island
JF  - The science of the total environment : an international journal for scientific research into the environment and its relationship with man
N2  - Obtaining representative hydrometric values is essential for characterizing extreme events, hydrological dynamics and detecting possible changes on the long-term hydrology. Reliability of streamflow data requires a temporal continuity and a maintenance of the gauging stations, which data are affected by epistemic and random sources of error. An assessment of discharge meterings' and stage-discharge rating curves' uncertainties were carried out by comparing the accuracy of the measuring instruments of two different hydrometric networks (i.e., one analogical and one digital) established in the same river location at the Mediterranean island of Mallorca. Furthermore, the effects of such uncertainties were assessed on the hydrological dynamics, considering the significant global change impacts beset this island. Evaluation was developed at four representative gauging stations of the hydrographic network with analogic (≈40 years) and digital (≈10 years) data series. The study revealed that the largest source of uncertainty in the analogical (28 to 274%) and in the digital (17–37%) networks were the stage-discharge rating curves. Their impact on the water resources was also evaluated at the event and annual scales, resulting in an average difference of water yields of 183% and 142% respectively. Such improvement on the comprehension of hydrometric networks uncertainties will dramatically benefit the interpretation of the long-term streamflow by providing better insights into the hydrologic and flood hazard planning, management and modelling.
KW  - Hydrometric networks
KW  - Stage-discharge
KW  - Metering
KW  - Uncertainty
KW  - Error propagation
Y1  - 2019
U6  - https://doi.org/10.1016/j.scitotenv.2019.02.158
SN  - 0048-9697
SN  - 1879-1026
VL  - 665
SP  - 968
EP  - 981
PB  - Elsevier Science
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Allroggen, Niklas Robin
A1  - Booth, Adam D.
A1  - Baker, Sandra E.
A1  - Ellwood, Stephen A.
A1  - Tronicke, Jens
T1  - High-resolution imaging and monitoring of animal tunnels using 3D ground-penetrating radar
JF  - Near surface geophysics
N2  - Ground-penetrating radar is widely used to provide highly resolved images of subsurface sedimentary structures, with implications for processes active in the vadose zone. Frequently overlooked among these structures are tunnels excavated by fossorial animals (e.g., moles). We present two repeated ground-penetrating radar surveys performed a year apart in 2016 and 2017. Careful three-dimensional data processing reveals, in each data set, a pattern of elongated structures that are interpreted as a subsurface mole tunnel network. Our data demonstrate the ability of three-dimensional ground-penetrating radar imaging to non-invasively delineate the small animal tunnels (similar to 5 cm diameter) at a higher spatial and geolocation resolution than has previously been achieved. In turn, this makes repeated surveys and, therefore, long-term monitoring possible. Our results offer valuable insight into the understanding of the near-surface and showcase a potential new application for a geophysical method as well as a non-invasive method of ecological surveying.
KW  - Ground-penetrating radar
KW  - Shallow subsurface
KW  - Environmental
Y1  - 2019
U6  - https://doi.org/10.1002/nsg.12039
SN  - 1569-4445
SN  - 1873-0604
VL  - 17
IS  - 3
SP  - 291
EP  - 298
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Kaya, Mustafa Yücel
A1  - Dupont-Nivet, Guillaume
A1  - Proust, Jean‐Noël
A1  - Roperch, Pierrick
A1  - Bougeois, Laurie
A1  - Meijer, Niels
A1  - Frieling, Joost
A1  - Fioroni, Chiara
A1  - Altiner, Sevinç Özkan
A1  - Vardar, Ezgi
A1  - Barbolini, Natasha
A1  - Stoica, Marius
A1  - Aminov, Jovid
A1  - Mamtimin, Mehmut
A1  - Zhaojie, Guo
T1  - Paleogene evolution and demise of the proto-Paratethys Sea in Central Asia (Tarim and Tajik basins)
BT  - Role of intensified tectonic activity at ca. 41 Ma
JF  - Basin research
N2  - The proto-Paratethys Sea covered a vast area extending from the Mediterranean Tethys to the Tarim Basin in western China during Cretaceous and early Paleogene. Climate modelling and proxy studies suggest that Asian aridification has been governed by westerly moisture modulated by fluctuations of the proto-Paratethys Sea. Transgressive and regressive episodes of the proto-Paratethys Sea have been previously recognized but their timing, extent and depositional environments remain poorly constrained. This hampers understanding of their driving mechanisms (tectonic and/or eustatic) and their contribution to Asian aridification. Here, we present a new chronostratigraphic framework based on biostratigraphy and magnetostratigraphy as well as a detailed palaeoenvironmental analysis for the Paleogene proto-Paratethys Sea incursions in the Tajik and Tarim basins. This enables us to identify the major drivers of marine fluctuations and their potential consequences on Asian aridification. A major regional restriction event, marked by the exceptionally thick (<= 400 m) shelf evaporites is assigned a Danian-Selandian age (ca. 63-59 Ma) in the Aertashi Formation. This is followed by the largest recorded proto-Paratethys Sea incursion with a transgression estimated as early Thanetian (ca. 59-57 Ma) and a regression within the Ypresian (ca. 53-52 Ma), both within the Qimugen Formation. The transgression of the next incursion in the Kalatar and Wulagen formations is now constrained as early Lutetian (ca. 47-46 Ma), whereas its regression in the Bashibulake Formation is constrained as late Lutetian (ca. 41 Ma) and is associated with a drastic increase in both tectonic subsidence and basin infilling. The age of the final and least pronounced sea incursion restricted to the westernmost margin of the Tarim Basin is assigned as Bartonian-Priabonian (ca. 39.7-36.7 Ma). We interpret the long-term westward retreat of the proto-Paratethys Sea starting at ca. 41 Ma to be associated with far-field tectonic effects of the Indo-Asia collision and Pamir/Tibetan plateau uplift. Short-term eustatic sea level transgressions are superimposed on this long-term regression and seem coeval with the transgression events in the other northern Peri-Tethyan sedimentary provinces for the 1st and 2nd sea incursions. However, the 3rd sea incursion is interpreted as related to tectonism. The transgressive and regressive intervals of the proto-Paratethys Sea correlate well with the reported humid and arid phases, respectively in the Qaidam and Xining basins, thus demonstrating the role of the proto-Paratethys Sea as an important moisture source for the Asian interior and its regression as a contributor to Asian aridification.
KW  - aridification
KW  - Asia
KW  - biostratigraphy
KW  - climate
KW  - magnetostratigraphy
KW  - microfossil
KW  - Paleogene
KW  - Pamir
KW  - proto-Paratethys
KW  - regression
KW  - Tajik Basin
KW  - Tarim Basin
KW  - tectonism
KW  - westerlies
Y1  - 2018
U6  - https://doi.org/10.1111/bre.12330
SN  - 0950-091X
SN  - 1365-2117
VL  - 31
IS  - 3
SP  - 461
EP  - 486
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Riechelman, Dana F. C.
A1  - Fohlmeister, Jens Bernd
A1  - Kluge, Tobias
A1  - Jochum, Klaus Peter
A1  - Richter, Detlev K.
A1  - Deininger, Michael
A1  - Friedrich, Ronny
A1  - Frank, Norbert
A1  - Scholz, Denis
T1  - Evaluating the potential of tree-ring methodology for cross-dating of three annually laminated stalagmites from Zoolithencave (SE Germany)
JF  - Quaternary geochronology : the international research and review journal on advances in quaternary dating techniques
N2  - Three small stalagmites from Zoolithencave (southern Germany) show visible laminae, which consist of a clear and a brownish, pigmented layer pair. This potentially provides the opportunity to construct precise chronologies by counting annual laminae. The growth period of the three stalagmites was constrained by the C-14 bomb peak in the youngest part of all three stalagmites and C-14-dating of a piece of charcoal in the consolidated base part of stalagmite Zoo-rez-2. These data suggest an age of AD 1970 for the top laminae and a lower age limit of AD 1973-1682 or AD 1735-1778. Laminae were counted and their thickness determined on scanned thin sections of all stalagmites. On stalagmites Zoo-rez-1 and -2, three tracks were measured near the growth axes, each separated into three sections at prominent anchor laminae (I, II, III). Each section was replicated three times (a, b, c). For Zoo-rez-3, only one track was measured. The total number of laminae counted for Zoo-rez-1 ranges from 138 to 177, for Zoo-rez-2 from 119 to 145, and for Zoo-rez-3 from 159 to 166. The numbers agree well with the range constrained by the bomb peak and the age of the charcoal, which supports the annual origin of the laminae. The replicated measurements of the different tracks as well as the three different tracks on the stalagmites Zoo-rez-1 and-2 were cross-dated using the TSAP-Win (R) tree-ring software. This software is very useful for cross-dating because it enables to insert or delete missing or false laminae as well as identifying common pattern by shifting the series back and forth in time. However, visual inspection of the thin sections was necessary to confirm detection of missing or false laminae by TSAP-Win (R). For all three Zoo-rez speleothems, crossdating of the mean lamina thickness series was not possible due to a missing common pattern. The cross-dating procedure results in three refined chronologies for the three Zoo-rez stalagmites of ranging from AD 1821-1970 (Zoo-rez-1), AD 1835-1970 (Zoo-rez-2), and AD 1808-1970 (Zoo-rez-3).
KW  - Speleothems
KW  - Annual laminae
KW  - Lamina thickness
KW  - C-14 bomb peak
KW  - Tree-ring software
KW  - Cross-dating
Y1  - 2019
U6  - https://doi.org/10.1016/j.quageo.2019.04.001
SN  - 1871-1014
SN  - 1878-0350
VL  - 52
SP  - 37
EP  - 50
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Eberli, Gregor P.
A1  - Bernoulli, Daniel
A1  - Vecsei, Adam
A1  - Sekti, Rizky
A1  - Grasmueck, Mark
A1  - Lüdmann, Thomas
A1  - Anselmetti, Flavio S.
A1  - Mutti, Maria
A1  - Della Porta, Giovanna
T1  - A Cretaceous carbonate delta drift in the Montagna della Maiella, Italy
JF  - Sedimentology : the journal of the International Association of Sedimentologists
N2  - The Upper Cretaceous (Campanian-Maastrichtian) bioclastic wedge of the Orfento Formation in the Montagna della Maiella, Italy, is compared to newly discovered contourite drifts in the Maldives. Like the drift deposits in the Maldives, the Orfento Formation fills a channel and builds a Miocene delta-shaped and mounded sedimentary body in the basin that is similar in size to the approximately 350 km(2) large coarse-grained bioclastic Miocene delta drifts in the Maldives. The composition of the bioclastic wedge of the Orfento Formation is also exclusively bioclastic debris sourced from the shallow-water areas and reworked clasts of the Orfento Formation itself. In the near mud-free succession, age-diagnostic fossils are sparse. The depositional textures vary from wackestone to float-rudstone and breccia/conglomerates, but rocks with grainstone and rudstone textures are the most common facies. In the channel, lensoid convex-upward breccias, cross-cutting channelized beds and thick grainstone lobes with abundant scours indicate alternating erosion and deposition from a high-energy current. In the basin, the mounded sedimentary body contains lobes with a divergent progradational geometry. The lobes are built by decametre thick composite megabeds consisting of sigmoidal clinoforms that typically have a channelized topset, a grainy foreset and a fine-grained bottomset with abundant irregular angular clasts. Up to 30 m thick channels filled with intraformational breccias and coarse grainstones pinch out downslope between the megabeds. In the distal portion of the wedge, stacked grainstone beds with foresets and reworked intraclasts document continuous sediment reworking and migration. The bioclastic wedge of the Orfento Formation has been variously interpreted as a succession of sea-level controlled slope deposits, a shoaling shoreface complex, or a carbonate tidal delta. Current-controlled delta drifts in the Maldives, however, offer a new interpretation because of their similarity in architecture and composition. These similarities include: (i) a feeder channel opening into the basin; (ii) an excavation moat at the exit of the channel; (iii) an overall mounded geometry with an apex that is in shallower water depth than the source channel; (iv) progradation of stacked lobes; (v) channels that pinch out in a basinward direction; and (vi) smaller channelized intervals that are arranged in a radial pattern. As a result, the Upper Cretaceous (Campanian-Maastrichtian) bioclastic wedge of the Orfento Formation in the Montagna della Maiella, Italy, is here interpreted as a carbonate delta drift.
KW  - Carbonate contourite drift
KW  - delta drift
KW  - Maiella Mountains
KW  - Orfento Formation
KW  - prograding lobes
Y1  - 2019
U6  - https://doi.org/10.1111/sed.12590
SN  - 0037-0746
SN  - 1365-3091
VL  - 66
IS  - 4
SP  - 1266
EP  - 1301
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Tolorza, Violeta
A1  - Mohr, Christian Heinrich
A1  - Carretier, Sebastien
A1  - Serey, Amador
A1  - Sepulveda, Sergio A.
A1  - Tapia, Joseline
A1  - Pinto, Luisa
T1  - Suspended sediments in chilean rivers reveal low postseismic erosion after the maule earthquake (Mw 8.8) during a severe drought
JF  - Journal of geophysical research : Earth surface
N2  - We address the question of whether all large-magnitude earthquakes produce an erosion peak in the subaerial components of fluvial catchments. We evaluate the sediment flux response to the Maule earthquake in the Chilean Andes (Mw 8.8) using daily suspended sediment records from 31 river gauges. The catchments cover drainage areas of 350 to around 10,000 km(2), including a wide range of topographic slopes and vegetation cover of the Andean western flank. We compare the 3- to 8-year postseismic record of sediment flux to each of the following preseismic periods: (1) all preseismic data, (2) a 3-year period prior to the seismic event, and (3) the driest preseismic periods, as drought conditions prevailed in the postseismic period. Following the earthquake, no increases in suspended sediment flux were observed for moderate to high percentiles of the streamflow distribution (mean, median, and >= 75th percentile). However, more than half of the examined stations showed increased sediment flux during baseflow. By using a Random Forest approach, we evaluate the contributions of seismic intensities, peak ground accelerations, co-seismic landslides, hydroclimatic conditions, topography, lithology, and land cover to explain the observed changes in suspended sediment concentration and fluxes. We find that the best predictors are hillslope gradient, low-vegetation cover, and changes in streamflow discharge. This finding suggests a combined first-order control of topography, land cover, and hydrology on the catchment-wide erosion response. We infer a reduced sediment connectivity due to the postseismic drought, which increased the residence time of sediment detached and remobilized following the Maule earthquake.
KW  - earthquake
KW  - suspended sediment
KW  - Maule megathrust
KW  - Chile
KW  - catchment
Y1  - 2019
U6  - https://doi.org/10.1029/2018JF004766
SN  - 2169-9003
SN  - 2169-9011
VL  - 124
IS  - 6
SP  - 1378
EP  - 1397
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Clubb, Fiona J.
A1  - Bookhagen, Bodo
A1  - Rheinwalt, Aljoscha
T1  - Clustering river profiles to classify geomorphic domains
JF  - Journal of geophysical research : Earth surface
N2  - The structure and organization of river networks has been used for decades to investigate the influence of climate and tectonics on landscapes. The majority of these studies either analyze rivers in profile view by extracting channel steepness or calculate planform metrics such as drainage density. However, these techniques rely on the assumption of homogeneity: that intrinsic and external factors are spatially or temporally invariant over the measured profile. This assumption is violated for the majority of Earth's landscapes, where variations in uplift rate, rock strength, climate, and geomorphic process are almost ubiquitous. We propose a method for classifying river profiles to identify landscape regions with similar characteristics by adapting hierarchical clustering algorithms developed for time series data. We first test our clustering on two landscape evolution scenarios and find that we can successfully cluster regions with different erodibility and detect the transient response to sudden base level fall. We then test our method in two real landscapes: first in Bitterroot National Forest, Idaho, where we demonstrate that our method can detect transient incision waves and the topographic signature of fluvial and debris flow process regimes; and second, on Santa Cruz Island, California, where our technique identifies spatial patterns in lithology not detectable through normalized channel steepness analysis. By calculating channel steepness separately for each cluster, our method allows the extraction of more reliable steepness metrics than if calculated for the landscape as a whole. These examples demonstrate the method's ability to disentangle fluvial morphology in complex lithological and tectonic settings.
KW  - clustering
KW  - river networks
KW  - topographic analysis
KW  - landscape evolution modeling
Y1  - 2019
U6  - https://doi.org/10.1029/2019JF005025
SN  - 2169-9003
SN  - 2169-9011
VL  - 124
IS  - 6
SP  - 1417
EP  - 1439
PB  - American Geophysical Union
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Frijia, Gianluca
A1  - Forkner, R.
A1  - Minisini, D.
A1  - Pacton, M.
A1  - Struck, Ulrich
A1  - Mutti, Maria
T1  - Cyanobacteria proliferation in the cenomanian-turonian boundary interval of the apennine carbonate platform:
BT  - immediate response to the environmental perturbations associated with OAE-2?
JF  - Geochemistry, geophysics, geosystems
N2  - Oceanic Anoxic Event-2 (OAE-2; Cenomanian-Turonian) is characterized by extensive deposition of organic carbon-rich deposits (black shales) in ocean basins worldwide as result of a major perturbation of the global carbon cycle. While the sedimentological, geochemical, and paleontological aspects of deep water expressions of OAE-2 have been intensively studied in the last few decades, much less attention has been given to the coeval shallow water deposits. In this study, we present the results of a detailed facies and petrographic (optical microscope and scanning electron microscopy) and geochemical studies (delta C-13(carb), delta C-13 (org), delta N-15(bulk), TOC, and Rock-Eval pyrolysis) on two key shallow marine sections from the Apennine Carbonate Platform (ACP; Italy). Here a continuous record of shallow water carbonates through the OAE-2 interval is preserved, offering the unique opportunity to document the archive of paleoenvironmental changes in a neritic setting, at a tropical latitude and far from the influence of a large continental block. Two conspicuous intervals are characterized by abundant and closely spaced dark microbial laminites found at correlative stratigraphic horizons in the two stratigraphic sections. These laminites contain elevated concentrations of TOC (up to 1%) relative to microbial capping cycles laminites stratigraphically above and below. The organic matter preserved in these fine-grained laminites is dominated by cyanobacteria remains, which accounted for most of the organic matter produced on the ACP in these intervals. Our study suggests that Tethyan carbonate platforms experienced significant biological changes during OAE-2, alternating, in few kiloyears, between eutrophic phases dominated by microbial communities and mesotrophic/oligotrophic conditions favoring normal carbonate production/sedimentation. The synchronous occurrence of microbialite facies at different locations across the ACP and on other platforms worldwide (e.g., Mexico and Croatia) suggests a causal link between Large Igneous Province volcanism and the environmental conditions necessary to trigger cyanobacterial proliferation on shallow carbonate platforms.
KW  - OAE-2
KW  - Apennine Carbonate Platform (ACP)
KW  - Cyanobacteria
KW  - C isotopes
KW  - N isotopes
Y1  - 2019
U6  - https://doi.org/10.1029/2019GC008306
SN  - 1525-2027
VL  - 20
IS  - 6
SP  - 2698
EP  - 2716
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Brieger, Frederic
A1  - Herzschuh, Ulrike
A1  - Pestryakova, Luidmila Agafyevna
A1  - Bookhagen, Bodo
A1  - Zakharov, Evgenii S.
A1  - Kruse, Stefan
T1  - Advances in the Derivation of Northeast Siberian Forest Metrics Using High-Resolution UAV-Based Photogrammetric Point Clouds
JF  - Remote sensing
N2  - Forest structure is a crucial component in the assessment of whether a forest is likely to act as a carbon sink under changing climate. Detailed 3D structural information about the tundra–taiga ecotone of Siberia is mostly missing and still underrepresented in current research due to the remoteness and restricted accessibility. Field based, high-resolution remote sensing can provide important knowledge for the understanding of vegetation properties and dynamics. In this study, we test the applicability of consumer-grade Unmanned Aerial Vehicles (UAVs) for rapid calculation of stand metrics in treeline forests. We reconstructed high-resolution photogrammetric point clouds and derived canopy height models for 10 study sites from NE Chukotka and SW Yakutia. Subsequently, we detected individual tree tops using a variable-window size local maximum filter and applied a marker-controlled watershed segmentation for the delineation of tree crowns. With this, we successfully detected 67.1% of the validation individuals. Simple linear regressions of observed and detected metrics show a better correlation (R2) and lower relative root mean square percentage error (RMSE%) for tree heights (mean R2 = 0.77, mean RMSE% = 18.46%) than for crown diameters (mean R2 = 0.46, mean RMSE% = 24.9%). The comparison between detected and observed tree height distributions revealed that our tree detection method was unable to representatively identify trees <2 m. Our results show that plot sizes for vegetation surveys in the tundra–taiga ecotone should be adapted to the forest structure and have a radius of >15–20 m to capture homogeneous and representative forest stands. Additionally, we identify sources of omission and commission errors and give recommendations for their mitigation. In summary, the efficiency of the used method depends on the complexity of the forest’s stand structure.
KW  - UAV
KW  - photogrammetry
KW  - remote sensing
KW  - structure from motion
KW  - tundra-taiga ecotone
KW  - point cloud
KW  - forest structure
Y1  - 2019
U6  - https://doi.org/10.3390/rs11121447
SN  - 2072-4292
VL  - 11
IS  - 12
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Sobolev, Stephan Vladimir
A1  - Brown, Michael
T1  - Surface erosion events controlled the evolution of plate tectonics on Earth
JF  - Nature : international weekly journal of science
N2  - Plate tectonics is among the most important geological processes on Earth, but its emergence and evolution remain unclear. Here we extrapolate models of present-day plate tectonics to the past and propose that since about three billion years ago the rise of continents and the accumulation of sediments at continental edges and in trenches has provided lubrication for the stabilization of subduction and has been crucial in the development of plate tectonics on Earth. We conclude that the two largest surface erosion and subduction lubrication events occurred after the Palaeoproterozoic Huronian global glaciations (2.45 to 2.2 billion years ago), leading to the formation of the Columbia supercontinent, and after the Neoproterozoic ‘snowball’ Earth glaciations (0.75 to 0.63 billion years ago). The snowball Earth event followed the ‘boring billion’—a period of reduced plate tectonic activity about 1.75 to 0.75 billion years ago that was probably caused by a shortfall of sediments in trenches—and it kick-started the modern episode of active plate tectonics.
Y1  - 2019
U6  - https://doi.org/10.1038/s41586-019-1258-4
SN  - 0028-0836
SN  - 1476-4687
VL  - 570
IS  - 7759
SP  - 52
EP  - +
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Cordonnier, Guillaume
A1  - Bovy, Benoit
A1  - Braun, Jean
T1  - A versatile, linear complexity algorithm for flow routing in topographies with depressions
JF  - Earth surface dynamics
N2  - We present a new algorithm for solving the common problem of flow trapped in closed depressions within digital elevation models, as encountered in many applications relying on flow routing. Unlike other approaches (e.g., the Priority-Flood depression filling algorithm), this solution is based on the explicit computation of the flow paths both within and across the depressions through the construction of a graph connecting together all adjacent drainage basins. Although this represents many operations, a linear time complexity can be reached for the whole computation, making it very efficient. Compared to the most optimized solutions proposed so far, we show that this algorithm of flow path enforcement yields the best performance when used in landscape evolution models. In addition to its efficiency, our proposed method also has the advantage of letting the user choose among different strategies of flow path enforcement within the depressions (i.e., filling vs. carving). Furthermore, the computed graph of basins is a generic structure that has the potential to be reused for solving other problems as well, such as the simulation of erosion. This sequential algorithm may be helpful for those who need to, e.g., process digital elevation models of moderate size on single computers or run batches of simulations as part of an inference study.
Y1  - 2019
U6  - https://doi.org/10.5194/esurf-7-549-2019
SN  - 2196-6311
SN  - 2196-632X
VL  - 7
IS  - 2
SP  - 549
EP  - 562
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Meier, Lars A.
A1  - Krauze, Patryk
A1  - Prater, Isabel
A1  - Horn, Fabian
A1  - Schaefer, Carlos Ernesto Reynaud
A1  - Scholten, Thomas
A1  - Wagner, Dirk
A1  - Müller, Carsten Werner
A1  - Kühn, Peter
T1  - Pedogenic and microbial interrelation in initial soils under semiarid climate on James Ross Island, Antarctic Peninsula region
JF  - Biogeosciences
N2  - James Ross Island (JRI) offers the exceptional opportunity to study microbial-driven pedogenesis without the influence of vascular plants or faunal activities (e.g., penguin rookeries). In this study, two soil profiles from JRI (one at Santa Martha Cove - SMC, and another at Brandy Bay BB) were investigated, in order to gain information about the initial state of soil formation and its interplay with prokaryotic activity, by combining pedological, geochemical and microbiological methods. The soil profiles are similar with respect to topographic position and parent material but are spatially separated by an orographic barrier and therefore represent windward and leeward locations towards the mainly southwesterly winds. These different positions result in differences in electric conductivity of the soils caused by additional input of bases by sea spray at the windward site and opposing trends in the depth functions of soil pH and electric conductivity. Both soils are classified as Cryosols, dominated by bacterial taxa such as Actinobacteria, Proteobacteria, Acidobacteria, Gemmatimonadetes and Chloroflexi. A shift in the dominant taxa was observed below 20 cm in both soils as well as an increased abundance of multiple operational taxonomic units (OTUs) related to potential chemolithoautotrophic Acidiferrobacteraceae. This shift is coupled by a change in microstructure. While single/pellicular grain microstructure (SMC) and platy microstructure (BB) are dominant above 20 cm, lenticular microstructure is dominant below 20 cm in both soils. The change in microstructure is caused by frequent freeze-thaw cycles and a relative high water content, and it goes along with a development of the pore spacing and is accompanied by a change in nutrient content. Multivariate statistics revealed the influence of soil parameters such as chloride, sulfate, calcium and organic carbon contents, grain size distribution and pedogenic oxide ratios on the overall microbial community structure and explained 49.9% of its variation. The correlation of the pedogenic oxide ratios with the compositional distribution of microorganisms as well as the relative abundance certain microorganisms such as potentially chemolithotrophic Acidiferrobacteraceae-related OTUs could hint at an interplay between soil-forming processes and microorganisms.
Y1  - 2019
U6  - https://doi.org/10.5194/bg-16-2481-2019
SN  - 1726-4170
SN  - 1726-4189
VL  - 16
IS  - 12
SP  - 2481
EP  - 2499
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Estrany, Joan
A1  - Ruiz, Maurici
A1  - Calsamiglia, Aleix
A1  - Carriqui, Marc
A1  - Garcia-Comendador, Julian
A1  - Nadal, Miquel
A1  - Fortesa, Josep
A1  - López-Tarazón, José Andrés
A1  - Medrano, Hipolito
A1  - Gago, Jorge
T1  - Sediment connectivity linked to vegetation using UAVs
BT  - High-resolution imagery for ecosystem management
JF  - The science of the total environment : an international journal for scientific research into the environment and its relationship with man
N2  - In this study, a low-cost unmanned aerial vehicle was used to obtain multi-spectral high-resolution imagery (1.4 cmpx(-1)) from2 microcatchments (3.3 ha) with burned Mediterranean shrubland and pine forests. This imagery was used to calculate the blue normalized differential vegetation index and to generate digital elevation models for estimating the sediment connectivity index. Both indices enabled an integrated approach for deciphering how hydrological and sediment connectivity interact with vegetation as well as soil conservation structures. The application of spatial analysis improves our understanding of the feedback between biological and geomorphological processes. Local spatial data analysis established a significant link between local geomorphological and biological factors, enabling a precise identification of homogeneous areas at micro-catchment scale and the minimal size of vegetation units reacting to geomorphology as natural groups at plot-scale where management strategies and efforts should be applied. Establishing this local relationship between sediment connectivity and vegetation patterns through new and interdisciplinary methodologies represents a new strategy for the assessment of ecosystem dynamics and management.
KW  - Ecogeomorphology
KW  - Mediterranean shrubland
KW  - Burned areas
KW  - UAVs
KW  - BNDVI
KW  - Sediment connectivity
Y1  - 2019
U6  - https://doi.org/10.1016/j.scitotenv.2019.03.399
SN  - 0048-9697
SN  - 1879-1026
VL  - 671
SP  - 1192
EP  - 1205
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Köhn-Reich, Lisei
A1  - Bürger, Gerd
T1  - Dynamical prediction of Indian monsoon
BT  - past and present skill
JF  - International Journal of Climatology
N2  - Ongoing development of dynamical atmosphere-ocean general circulation models keep expectations high regarding seasonal predictions of Indian monsoon rainfall. This study compares past and present skill of four currently operating forecasting systems, CFSv2 from NCEP, ENSEMBLES, System 4 and the newest SEAS5 from ECMWF, by analysing correlations of respective hindcasts with observed all-India summer rainfall. For the common time period 1982-2005, only ENSEMBLES and CFSv2 give significantly skilful forecasts. It is shown that skill is highly dependent on the chosen time period. Especially the intense El Nino of 1997 seems to degrade the predictions, most notably for SEAS4 and SEAS5 which seem to be linked to El Nino too strongly. We show that by discarding that year, a regime shift in the 1990s is no longer visible. Overall, we observe a convergence of skill towards the present with correlations of about 0.4 for CFSv2 and of 0.6 for System 4 and SEAS5.
KW  - correlation skill
KW  - dynamical seasonal prediction
KW  - Indian summer monsoon
Y1  - 2019
U6  - https://doi.org/10.1002/joc.6039
SN  - 0899-8418
SN  - 1097-0088
VL  - 39
IS  - 8
SP  - 3574
EP  - 3581
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Weithoff, Guntram
A1  - Neumann, Catherin
A1  - Seiferth, Jacqueline
A1  - Weisse, Thomas
T1  - Living on the edge: reproduction, dispersal potential, maternal effects and local adaptation in aquatic, extremophilic invertebrates
JF  - Aquatic sciences : research across boundaries
N2  - Isolated extreme habitats are ideally suited to investigate pivotal ecological processes such as niche use, local adaptation and dispersal. Extremophilic animals living in isolated habitats face the problem that dispersal is limited through the absence of suitable dispersal corridors, which in turn facilitates local adaptation. We used five rotifer isolates from extremely acidic mining lakes with a pH of below 3 as model organisms to test whether these isolates are acidotolerant or acidophilic, whether they survive and reproduce at their niche edges (here pH 2 and circum-neutral pH) and whether local adaptation has evolved. To evaluate potential dispersal limitation, we tested whether animals and their parthenogenetic eggs survive and remain reproductive or viable at unfavourable pH-conditions. All five isolates were acidophilic with a pH-optimum in the range of 4-6, which is well above the pH (< 3) of their lakes of origin. At unfavourable high pH, in four out of the five isolates parthenogenetic females produced a high number of non-viable eggs. Females and eggs produced at favourable pH (4) remained vital at an otherwise unfavourable pH of 7, indicating that for dispersal no acidic dispersal corridors are necessary. Common garden experiments revealed no clear evidence for local adaptation in any of the five isolates. Despite their acidophilic nature, all five isolates can potentially disperse via circum-neutral water bodies as long as their residence time is short, suggesting a broader dispersal niche than their realized niche. Local adaptation might have been hampered by the low population sizes of the rotifers in their isolated habitat and the short time span the mining lakes have existed.
KW  - Common garden experiments
KW  - Extreme habitats
KW  - Extremophiles
KW  - Rotifers
KW  - Zooplankton
Y1  - 2019
U6  - https://doi.org/10.1007/s00027-019-0638-z
SN  - 1015-1621
SN  - 1420-9055
VL  - 81
IS  - 3
PB  - Springer
CY  - Basel
ER  - 
TY  - JOUR
A1  - Martin-Puertas, Celia
A1  - Lauterbach, Stefan
A1  - Allen, Judy R. M.
A1  - Perez, Marta
A1  - Blockley, Simon
A1  - Wulf, Sabine
A1  - Huntley, Brian
A1  - Brauer, Achim
T1  - Initial Mediterranean response to major climate reorganization during the last interglacial-glacial transition
JF  - Quaternary science reviews : the international multidisciplinary research and review journal
N2  - Millennial-scale Dansgaard Oeschger (DO) variability at northern high latitudes has influenced climatic and environmental conditions in the Mediterranean during the last glacial period. There is evidence that the hemispheric transmission of the DO variability occurred at the end of DO event 25; however, the exact timing and the trigger that activated the environmental response in the Mediterranean remains incompletely understood. Here, we provide evidence that the clear millennial-scale teleconnection between Greenland and the Mediterranean started at similar to 111.4 ka BP and was initiated by a sub-millennial scale cooling in Greenland (GI-25b). High-resolution sediment proxies and the pollen record of Lago Grande di Monticchio (MON), Italy, reflect climatic instability during the last millennium of the last interglacial, which was characterised by a first and short cooling episode (MON 1) at 111.44 +/- 0.69 ka BP, coinciding with the Greenland cold sub-event GI-25b in duration and timing (within dating uncertainties). MON and Greenland (NorthGRIP ice core) also agree in recording a subsequent warm rebound phase that abruptly culminated in the stadial MON 2/GS-25, marking the transition into the last glacial period. Our results show that the GI-25b triggered an early environmental response at MON to centennial-scale climate change in Greenland as a prelude to the millennial-scale teleconnection that was maintained during the glacial period.
KW  - Palaeoclimatology
KW  - Last interglacial-glacial transition
KW  - Millennial-scale variability
KW  - Mediterranean
KW  - Varved sediments
Y1  - 2019
U6  - https://doi.org/10.1016/j.quascirev.2019.05.019
SN  - 0277-3791
VL  - 215
SP  - 232
EP  - 241
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Deino, A. L.
A1  - Dommain, René
A1  - Keller, C. B.
A1  - Potts, R.
A1  - Behrensmeyer, A. K.
A1  - Beverly, E. J.
A1  - King, J.
A1  - Heil, C. W.
A1  - Stockhecke, M.
A1  - Brown, E. T.
A1  - Moerman, J.
A1  - deMenocal, P.
A1  - Deocampo, D.
A1  - Garcin, Yannick
A1  - Levin, N. E.
A1  - Lupien, R.
A1  - Owen, R. B.
A1  - Rabideaux, N.
A1  - Russell, J. M.
A1  - Scott, J.
A1  - Riedl, S.
A1  - Brady, K.
A1  - Bright, J.
A1  - Clark, J. B.
A1  - Cohen, A.
A1  - Faith, J. T.
A1  - Noren, A.
A1  - Muiruri, V.
A1  - Renaut, R.
A1  - Rucina, S.
A1  - Uno, K.
T1  - Chronostratigraphic model of a high-resolution drill core record of the past million years from the Koora Basin, south Kenya Rift: Overcoming the difficulties of variable sedimentation rate and hiatuses
JF  - Quaternary science reviews : the international multidisciplinary research and review journal
N2  - The Olorgesailie Drilling Project and the related Hominin Sites and Paleolakes Drilling Project in East Africa were initiated to test hypotheses and models linking environmental change to hominin evolution by drilling lake basin sediments adjacent to important archeological and paleoanthropological sites. Drill core OL012-1A recovered 139 m of sedimentary and volcaniclastic strata from the Koora paleolake basin, southern Kenya Rift, providing the opportunity to compare paleoenvironmental influences over the past million years with the parallel record exposed at the nearby Olorgesailie archeological site. To refine our ability to link core-to-outcrop paleoenvironmental records, we institute here a methodological framework for deriving a robust age model for the complex lithostratigraphy of OL012-1A. Firstly, chronostratigraphic control points for the core were established based on 4 Ar/39Ar ages from intercalated tephra deposits and a basal trachyte flow, as well as the stratigraphic position of the Brunhes-Matuyama geomagnetic reversal. This dataset was combined with the position and duration of paleosols, and analyzed using a new Bayesian algorithm for high-resolution age-depth modeling of hiatus-bearing stratigraphic sections. This model addresses three important aspects relevant to highly dynamic, nonlinear depositional environments: 1) correcting for variable rates of deposition, 2) accommodating hiatuses, and 3) quantifying realistic age uncertainty with centimetric resolution. Our method is applicable to typical depositional systems in extensional rifts as well as to drill cores from other dynamic terrestrial or aquatic environments. We use the core age model and lithostratigraphy to examine the inter connectivity of the Koora Basin to adjacent areas and sources of volcanism. (C) 2019 Elsevier Ltd. All rights reserved.
KW  - Pleistocene
KW  - Paleolimnology
KW  - East Africa
KW  - Sedimentology
KW  - Radiogenic isotopes
KW  - Bayesian modeling
KW  - paleosol
KW  - Tephrostratigraphy
KW  - Magnetostratigraphy
KW  - Kenya Rift
Y1  - 2019
U6  - https://doi.org/10.1016/j.quascirev.2019.05.009
SN  - 0277-3791
VL  - 215
SP  - 213
EP  - 231
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Ramage, Justine Lucille
A1  - Fortier, Daniel
A1  - Hugelius, Gustaf
A1  - Lantuit, Hugues
A1  - Morgenstern, Anne
T1  - Distribution of carbon and nitrogen along hillslopes in three valleys on Herschel Island, Yukon Territory, Canada
JF  - Catena : an interdisciplinary journal of soil science, hydrology, geomorphology focusing on geoecology and landscape evolution
N2  - Thermokarst results from the thawing of ice-rich permafrost and alters the biogeochemical cycling in the Arctic by reworking soil material and redistributing soil organic carbon (SOC) and total nitrogen (TN) along uplands, hillslopes, and lowlands. Understanding the impact of this redistribution is key to better estimating the storage of SOC in permafrost terrains. However, there are insufficient studies quantifying long-term impacts of thaw processes on the distribution of SOC and TN along hillslopes. We address this issue by providing estimates of SOC and TN stocks along the hillslopes of three valleys located on Herschel Island (Yukon, Canada), and by discussing the impact of hillslope thermokarst on the variability of SOC and TN stocks. We found that the average SOC and TN 0-100 cm stocks in the valleys were 26.4 +/- 8.9 kg C m(-2) and 2.1 +/- 0.6 kg N m(-2). We highlight the strong variability in the soils physical and geochemical properties within hillslope positions. High SOC stocks were found at the summits, essentially due to burial of organic matter by cryoturbation, and at the toeslopes due to impeded drainage which favored peat formation and SOC accumulation. The average carbon-to-nitrogen ratio in the valleys was 12.9, ranging from 9.7 to 18.9, and was significantly higher at the summits compared to the backslopes and footslopes (p < 0.05), suggesting a degradation of SOC downhill. Carbon and nitrogen contents and stocks were significantly lower on 16% of the sites that were previously affected by hillslope thermokarst (p < 0.05). Our results showed that lateral redistribution of SOC and TN due to hillslope thermokarst has a strong impact on the SOC storage in ice-rich permafrost terrains.
KW  - Hillslope thermokarst
KW  - Soil organic carbon storage
KW  - Catchment geomorphology
KW  - Permafrost degradation
Y1  - 2019
U6  - https://doi.org/10.1016/j.catena.2019.02.029
SN  - 0341-8162
SN  - 1872-6887
VL  - 178
SP  - 132
EP  - 140
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Soares Pereira, Francisco Jairo
A1  - Gomes Costa, Carlos Alexandre
A1  - Förster, Saskia
A1  - Brosinsky, Arlena
A1  - de Araujo, Jose Carlos
T1  - Estimation of suspended sediment concentration in an intermittent river using multi-temporal high-resolution satellite imagery
JF  - International journal of applied earth observation and geoinformation
N2  - There is a shortage of sediment-routing monitoring worldwide, despite its relevance to environmental processes. In drylands, where water resources are more vulnerable to the sediment dynamics, this flaw is even more harmful. In the semi-arid Caatinga biome in the North-east of Brazil, rivers are almost all intermittent and hydro-sedimentological monitoring is scarce. In the biome, water supply derives from thousands of surface reservoirs, whose water availability is liable to be reduced by siltation and sediment-related pollution. The goal of this research was to evaluate the potential of multi-temporal high-resolution satellite imagery (RapidEye) to assess the suspended sediment concentration (SSC) in the medium-sized intermittent Jaguaribe River, Brazil, during a 5-year period. We validated 15 one-, two- and three-band indices for SSC estimation based on RapidEye spectral bands deduced in the context of the present investigation and nine indices proposed in the literature for other optical sensors, by comparing them with in-situ concentration data. The in-situ SSC data ranged from 67 mg.L-1 to 230 mg.L-1. We concluded that RapidEye images can assess moderate SSC of intermittent rivers, even when their discharge is low. The RapidEye indices performed better than those from literature. The spectral band that best represented SSC was the near infrared, whose performance improved when associated with the green band. This conclusion agrees with literature findings for diverse sedimentological contexts. The three-band spectral indices performed worse than those with only one or two spectral bands, showing that the use of a third band did not enhance the model ability. Besides, we show that the hydrological characteristics of semi-arid intermittent rivers generate difficulties to monitor SSC using optical satellite remote sensing, such as time-concentrated sediment yield; and its association with recent rainfall events and, therefore, with cloudy sky.
KW  - Remote sensing
KW  - Sediment load
KW  - Dryland
KW  - Brazil
Y1  - 2019
U6  - https://doi.org/10.1016/j.jag.2019.02.009
SN  - 0303-2434
VL  - 79
SP  - 153
EP  - 161
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Roder, Giulia
A1  - Hudson, Paul
A1  - Taroili, Paolo
T1  - Flood risk perceptions and the willingness to pay for flood insurance in the Veneto region of Italy
JF  - International Journal of Disaster Risk Reduction
N2  - The floodplain of the Veneto region (north-east Italy) is one of the most inhabited and economically competitive urban landscapes in Europe. Moreover, recent flood events have caused millions of Euros in damage across the region. Due to the combined influence of climate change and socio-economic development, flood impacts are expected to grow. Therefore, it is important for all flood-prone individuals to actively manage and limit flood risk through property-level flood risk management as part of an integrated flood risk management strategy. This is in line with the calls for wider community engagement in risk management in the Sendai Framework for Disaster Risk Reduction and the Sustainable Development Goals. Therefore, an online-survey of Veneto region residents was conducted asking questions regarding flood risk perceptions, preparedness, and preferences towards flood insurance via self-stated willingness to pay (WTP). Our analysis provides an initial indication that while flood risk knowledge is high, it may not be sufficient to encourage proactive risk management. From the WTP values provided people seem reluctant to buy insurance. However, many respondents expressed that a compulsory insurance system may be acceptable. In such a scheme the estimated insurance premium could fall to between (sic)26 and (sic)42 per year, as compared to, potentially, (sic)800 under risk-based premiums, which falls within the majority of WTP estimates provided ((sic)0-(sic)250). Overall, we identify areas of future research that are critical for the better design of risk management policies, supporting the insurance companies in risk management and for recommendations regarding property-level risk management.
KW  - Flood risk
KW  - Risk perception
KW  - Preparedness
KW  - Willingness to pay
KW  - Italy
Y1  - 2019
U6  - https://doi.org/10.1016/j.ijdrr.2019.101172
SN  - 2212-4209
VL  - 37
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Ozturk, Ugur
A1  - Malik, Nishant
A1  - Cheung, Kevin
A1  - Marwan, Norbert
A1  - Kurths, Jürgen
T1  - A network-based comparative study of extreme tropical and frontal storm rainfall over Japan
JF  - Climate dynamics : observational, theoretical and computational research on the climate system
N2  - Frequent and intense rainfall events demand innovative techniques to better predict the extreme rainfall dynamics. This task requires essentially the assessment of the basic types of atmospheric processes that trigger extreme rainfall, and then to examine the differences between those processes, which may help to identify key patterns to improve predictive algorithms. We employ tools from network theory to compare the spatial features of extreme rainfall over the Japanese archipelago and surrounding areas caused by two atmospheric processes: the Baiu front, which occurs mainly in June and July (JJ), and the tropical storms from August to November (ASON). We infer from complex networks of satellite-derived rainfall data, which are based on the nonlinear correlation measure of event synchronization. We compare the spatial scales involved in both systems and identify different regions which receive rainfall due to the large spatial scale of the Baiu and tropical storm systems. We observed that the spatial scales involved in the Baiu driven rainfall extremes, including the synoptic processes behind the frontal development, are larger than tropical storms, which even have long tracks during extratropical transitions. We further delineate regions of coherent rainfall during the two seasons based on network communities, identifying the horizontal (east-west) rainfall bands during JJ over the Japanese archipelago, while during ASON these bands align with the island arc of Japan.
KW  - Extreme rainfall
KW  - Baiu
KW  - Tropical storms
KW  - Event synchronization
KW  - Complex networks
Y1  - 2019
U6  - https://doi.org/10.1007/s00382-018-4597-1
SN  - 0930-7575
SN  - 1432-0894
VL  - 53
IS  - 1-2
SP  - 521
EP  - 532
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Hovi, Jon
A1  - Sprinz, Detlef F.
A1  - Saelen, Håkon
A1  - Underdal, Arild
T1  - The Club Approach: A Gateway to Effective Climate Co-operation?
JF  - British Journal of Political Science
N2  - Although the Paris Agreement arguably made some progress, interest in supplementary approaches to climate change co-operation persist. This article examines the conditions under which a climate club might emerge and grow. Using agent-based simulations, it shows that even with less than a handful of major actors as initial members, a club can eventually reduce global emissions effectively. To succeed, a club must be initiated by the ‘right’ constellation of enthusiastic actors, offer sufficiently large incentives for reluctant countries and be reasonably unconstrained by conflicts between members over issues beyond climate change. A climate club is particularly likely to persist and grow if initiated by the United States and the European Union. The combination of club-good benefits and conditional commitments can produce broad participation under many conditions.
KW  - UNFCCC
KW  - climate change co-operation
KW  - climate clubs
KW  - club goods
KW  - conditional commitments
KW  - agent-based models
Y1  - 2019
U6  - https://doi.org/10.1017/S0007123416000788
SN  - 0007-1234
SN  - 1469-2112
VL  - 49
IS  - 3
SP  - 1071
EP  - 1096
PB  - Cambridge University Press
CY  - New York
ER  -