@article{PourteauSchererSchornetal.2019, author = {Pourteau, Amaury and Scherer, Erik E. and Schorn, Simon and Bast, Rebecca and Schmidt, Alexander and Ebert, Lisa}, title = {Thermal evolution of an ancient subduction interface revealed by Lu-Hf garnet geochronology, Halilbagi Complex (Anatolia)}, series = {Geoscience Frontiers}, volume = {10}, journal = {Geoscience Frontiers}, number = {1}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1674-9871}, doi = {10.1016/j.gsf.2018.03.004}, pages = {127 -- 148}, year = {2019}, abstract = {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.}, language = {en} } @article{BarthGeertsemaBevingtonetal.2019, author = {Barth, Sophia and Geertsema, Marten and Bevington, Alexandre R. and Bird, Alison L. and Clague, John J. and Millard, Tom and Bobrowsky, Peter T. and Hasler, Andreas and Liu, Hongjiang}, title = {Landslide response to the 27 October 2012 earthquake (M-W 7.8), southern Haida Gwaii, British Columbia, Canada}, series = {Landslides : journal of the International Consortium on Landslides, ICL}, volume = {17}, journal = {Landslides : journal of the International Consortium on Landslides, ICL}, number = {3}, publisher = {Springer}, address = {Heidelberg}, issn = {1612-510X}, doi = {10.1007/s10346-019-01292-7}, pages = {517 -- 526}, year = {2019}, abstract = {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.}, language = {en} } @article{Herzschuh2019, author = {Herzschuh, Ulrike}, title = {Legacy of the Last Glacial on the present-day distribution of deciduous versus evergreen boreal forests}, series = {Global ecology and biogeography : a journal of macroecology}, volume = {29}, journal = {Global ecology and biogeography : a journal of macroecology}, number = {2}, publisher = {John Wiley \& Sons, Inc.}, address = {Hoboken}, issn = {1466-822X}, doi = {10.1111/geb.13018}, pages = {198 -- 206}, year = {2019}, abstract = {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.}, language = {en} } @article{SublettSendulaLamadridetal.2019, author = {Sublett, David Matthew and Sendula, Eszter and Lamadrid, Hector and Steele-MacInnis, Matthew and Spiekermann, Georg and Burruss, Robert C. and Bodnar, Robert J.}, title = {Shift in the Raman symmetric stretching band of N-2, CO2, and CH4 as a function of temperature, pressure, and density}, series = {Journal of Raman spectroscopy : JRS}, volume = {51}, journal = {Journal of Raman spectroscopy : JRS}, number = {3}, publisher = {Wiley}, address = {Hoboken}, issn = {0377-0486}, doi = {10.1002/jrs.5805}, pages = {555 -- 568}, year = {2019}, abstract = {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.}, language = {en} } @article{TolorzaMohrCarretieretal.2019, author = {Tolorza, Violeta and Mohr, Christian Heinrich and Carretier, Sebastien and Serey, Amador and Sepulveda, Sergio A. and Tapia, Joseline and Pinto, Luisa}, title = {Suspended sediments in chilean rivers reveal low postseismic erosion after the maule earthquake (Mw 8.8) during a severe drought}, series = {Journal of geophysical research : Earth surface}, volume = {124}, journal = {Journal of geophysical research : Earth surface}, number = {6}, publisher = {American Geophysical Union}, address = {Washington}, issn = {2169-9003}, doi = {10.1029/2018JF004766}, pages = {1378 -- 1397}, year = {2019}, abstract = {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.}, language = {en} } @article{FortesaGarciaComendadorCalsamigliaetal.2019, author = {Fortesa, Josep and Garc{\´i}a-Comendador, Julian and Calsamiglia, A. and L{\´o}pez-Taraz{\´o}n, Jos{\´e} Andr{\´e}s and Latron, J. and Alorda, B. and Estrany, Joan}, title = {Comparison of stage/discharge rating curves derived from different recording systems}, series = {The science of the total environment : an international journal for scientific research into the environment and its relationship with man}, volume = {665}, journal = {The science of the total environment : an international journal for scientific research into the environment and its relationship with man}, publisher = {Elsevier Science}, address = {Amsterdam}, issn = {0048-9697}, doi = {10.1016/j.scitotenv.2019.02.158}, pages = {968 -- 981}, year = {2019}, abstract = {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.}, language = {en} } @article{WickertSchildgen2019, author = {Wickert, Andrew D. and Schildgen, Taylor F.}, title = {Long-profile evolution of transport-limited gravel-bed rivers}, series = {Earth surface dynamics}, volume = {7}, journal = {Earth surface dynamics}, number = {1}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {2196-6311}, doi = {10.5194/esurf-7-17-2019}, pages = {17 -- 43}, year = {2019}, abstract = {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.}, language = {en} } @article{KaczorekPuppeBusseetal.2019, author = {Kaczorek, Danuta and Puppe, Daniel and Busse, Jacqueline and Sommer, Michael}, title = {Effects of phytolith distribution and characteristics on extractable silicon fractions in soils under different vegetation - An exploratory study on loess}, series = {Geoderma : an international journal of soil science}, volume = {356}, journal = {Geoderma : an international journal of soil science}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0016-7061}, doi = {10.1016/j.geoderma.2019.113917}, pages = {16}, year = {2019}, abstract = {The significance of phytoliths for the control of silicon (Si) fluxes from terrestrial to aquatic ecosystems has been recognized as a key factor. Humankind actively influences Si fluxes by intensified land use, i.e., agriculture and forestry, on a global scale. We hypothesized phytolith distribution and assemblages in soils of agricultural and forestry sites to be controlled by vegetation (which is directed by land use) with direct effects on extractable Si fractions driven mainly by phytolith characteristics, i.e., dissolution status (dissolution signs) and morphology (morphotype proportions). To test our hypothesis we combined different chemical extraction methods (calcium chloride, ammonium oxalate, Tiron) for the quantification of different Si fractions (plant available Si, Si adsorbed to/occluded in pedogenic oxides/hydroxides, amorphous Si) and microscopic techniques (light microscopy, confocal laser scanning microscopy, scanning electron microscopy) for detailed analyses of phytoliths extracted using gravimetric separation (physical extraction) from exemplary loess soils of agricultural (arable land and grassland/meadow) and forestry (beech and pine) sites in Poland. We found differences in dissolution signs, morphotype proportions, and vertical distribution of phytoliths in soil horizons per site. In general, dominant morphotypes of assignable phytoliths in the studied soil profiles were elongate phytoliths and short cells, both of which are typical for grass-dominated vegetation. However, the organic layers of forest soils were dominated by globular phytoliths, which are typical indicators for mosses. As expected soil horizons under different vegetation generally were characterized by differences in extractable Si fractions, especially in the upper soil horizons. However, phytogenic Si pools counter-intuitively showed no correlations with chemically extracted Si fractions and soil pH at all. Our findings indicate that it is necessary to combine microscopic analyses and Si extraction techniques for examinations of Si cycling in biogeosystems, because extractions of Si fractions alone do not allow drawing any conclusions about phytolith characteristics or interactions between phytolith pools and chemically extractable Si fractions and do not necessarily reflect phytogenic Si pool quantities in soils and vice versa.}, language = {en} } @article{BufeTurowskiBurbanketal.2019, author = {Bufe, Aaron and Turowski, Jens M. and Burbank, Douglas W. and Paola, Chris and Wickert, Andrew D. and Tofelde, Stefanie}, title = {Controls on the lateral channel-migration rate of braided channel systems in coarse non-cohesive sediment}, series = {Earth surface processes and landforms : the journal of the British Geomorphological Research Group}, volume = {44}, journal = {Earth surface processes and landforms : the journal of the British Geomorphological Research Group}, number = {14}, publisher = {Wiley}, address = {Hoboken}, issn = {0197-9337}, doi = {10.1002/esp.4710}, pages = {2823 -- 2836}, year = {2019}, abstract = {Lateral movements of alluvial river channels control the extent and reworking rates of alluvial fans, floodplains, deltas, and alluvial sections of bedrock rivers. These lateral movements can occur by gradual channel migration or by sudden changes in channel position (avulsions). Whereas models exist for rates of river avulsion, we lack a detailed understanding of the rates of lateral channel migration on the scale of a channel belt. In a two-step process, we develop here an expression for the lateral migration rate of braided channel systems in coarse, non-cohesive sediment. On the basis of photographic and topographic data from laboratory experiments of braided channels performed under constant external boundary conditions, we first explore the impact of autogenic variations of the channel-system geometry (i.e. channel-bank heights, water depths, channel-system width, and channel slope) on channel-migration rates. In agreement with theoretical expectations, we find that, under such constant boundary conditions, the laterally reworked volume of sediment is constant and lateral channel-migration rates scale inversely with the channel-bank height. Furthermore, when channel-bank heights are accounted for, lateral migration rates are independent of the remaining channel geometry parameters. These constraints allow us, in a second step, to derive two alternative expressions for lateral channel-migration rates under different boundary conditions using dimensional analysis. Fits of a compilation of laboratory experiments to these expressions suggest that, for a given channel bank-height, migration rates are strongly sensitive to water discharges and more weakly sensitive to sediment discharges. In addition, external perturbations, such as changes in sediment and water discharges or base level fall, can indirectly affect lateral channel-migration rates by modulating channel-bank heights.}, language = {en} } @article{CarvalhoBartoliFerrietal.2019, author = {Carvalho, Bruna B. and Bartoli, Omar and Ferri, Fabio and Cesare, Bernardo and Ferrero, Silvio and Remusat, Laurent and Capizzi, Luca Samuele and Poli, Stefano}, title = {Anatexis and fluid regime of the deep continental crust: New clues from melt and fluid inclusions in metapelitic migmatites from Ivrea Zone (NW Italy)}, series = {Journal of metamorphic geology}, volume = {37}, journal = {Journal of metamorphic geology}, number = {7}, publisher = {Wiley}, address = {Hoboken}, issn = {0263-4929}, doi = {10.1111/jmg.12463}, pages = {951 -- 975}, year = {2019}, abstract = {We investigate the inclusions hosted in peritectic garnet from metapelitic migmatites of the Kinzigite Formation (Ivrea Zone, NW Italy) to evaluate the starting composition of the anatectic melt and fluid regime during anatexis throughout the upper amphibolite facies, transition, and granulite facies zones. Inclusions have negative crystal shapes, sizes from 2 to 10 mu m and are regularly distributed in the core of the garnet. Microstructural and micro-Raman investigations indicate the presence of two types of inclusions: crystallized silicate melt inclusions (i.e., nanogranitoids, NI), and fluid inclusions (FI). Microstructural evidence suggests that FI and NI coexist in the same cluster and are primary (i.e., were trapped simultaneously during garnet growth). FI have similar compositions in the three zones and comprise variable proportions of CO2, CH4, and N-2, commonly with siderite, pyrophyllite, and kaolinite, suggesting a COHN composition of the trapped fluid. The mineral assemblage in the NI contains K-feldspar, plagioclase, quartz, biotite, muscovite, chlorite, graphite and, rarely, calcite. Polymorphs such as kumdykolite, cristobalite, tridymite, and less commonly kokchetavite, were also found. Rehomogenized NI from the different zones show that all the melts are leucogranitic but have slightly different compositions. In samples from the upper amphibolite facies, melts are less mafic (FeO + MgO = 2.0-3.4 wt\%), contain 860-1700 ppm CO2 and reach the highest H2O contents (6.5-10 wt\%). In the transition zone melts have intermediate H2O (4.8-8.5 wt\%), CO2 (457-1534 ppm) and maficity (FeO + MgO = 2.3-3.9 wt\%). In contrast, melts at granulite facies reach highest CaO, FeO + MgO (3.2-4.7 wt\%), and CO2 (up to 2,400 ppm), with H2O contents comparable (5.4-8.3 wt\%) to the other two zones. Our results represent the first clear evidence for carbonic fluid-present melting in the Ivrea Zone. Anatexis of metapelites occurred through muscovite and biotite breakdown melting in the presence of a COH fluid, in a situation of fluid-melt immiscibility. The fluid is assumed to have been internally derived, produced initially by devolatilization of hydrous silicates in the graphitic protolith, then as a result of oxidation of carbon by consumption of Fe3+-bearing biotite during melting. Variations in the compositions of the melts are interpreted to result from higher T of melting. The H2O contents of the melts throughout the three zones are higher than usually assumed for initial H2O contents of anatectic melts. The CO2 contents are highest at granulite facies, and show that carbon-contents of crustal magmas are not negligible at high T. The activity of H2O of the fluid dissolved in granitic melts decreases with increasing metamorphic grade. Carbonic fluid-present melting of the deep continental crust represents, together with hydrate-breakdown melting reactions, an important process in the origin of crustal anatectic granitoids.}, language = {en} } @article{MuellerLichtCampbelletal.2019, author = {Mueller, Megan A. and Licht, Alexis and Campbell, C. and Ocakoglu, F. and Taylor, Marc Hollis and Burch, L. and Ugrai, Tamas and Kaya, M. and Kurtoglu, B. and Coster, P. M. C. and Metais, Mustafa Y{\"u}cel and Beard, Kenneth Christopher}, title = {Collision Chronology Along the Izmir-Ankara-Erzincan Suture Zone: Insights From the Saricakaya Basin, Western Anatolia}, series = {Tectonics}, volume = {38}, journal = {Tectonics}, number = {10}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0278-7407}, doi = {10.1029/2019TC005683}, pages = {3652 -- 3674}, year = {2019}, abstract = {Debate persists concerning the timing and geodynamics of intercontinental collision, style of syncollisional deformation, and development of topography and fold-and-thrust belts along the >1,700-km-long Izmir-Ankara-Erzincan suture zone (IAESZ) in Turkey. Resolving this debate is a necessary precursor to evaluating the integrity of convergent margin models and kinematic, topographic, and biogeographic reconstructions of the Mediterranean domain. Geodynamic models argue either for a synchronous or diachronous collision during either the Late Cretaceous and/or Eocene, followed by Eocene slab breakoff and postcollisional magmatism. We investigate the collision chronology in western Anatolia as recorded in the sedimentary archives of the 90-km-long Saricakaya Basin perched at shallow structural levels along the IAESZ. Based on new zircon U-Pb geochronology and depositional environment and sedimentary provenance results, we demonstrate that the Saricakaya Basin is an Eocene sedimentary basin with sediment sourced from both the IAESZ and Sogut Thrust fault to the south and north, respectively, and formed primarily by flexural loading from north-south shortening along the syncollisional Sogut Thrust. Our results refine the timing of collision between the Anatolides and Pontide terranes in western Anatolia to Maastrichtian-Middle Paleocene and Early Eocene crustal shortening and basin formation. Furthermore, we demonstrate contemporaneous collision, deformation, and magmatism across the IAESZ, supporting synchronous collision models. We show that regional postcollisional magmatism can be explained by renewed underthrusting instead of slab breakoff. This new IAESZ chronology provides additional constraints for kinematic, geodynamic, and biogeographic reconstructions of the Mediterranean domain.}, language = {en} } @article{AichnerMakhmudovRajabovetal.2019, author = {Aichner, Bernhard and Makhmudov, Zafar and Rajabov, Iljomjon and Zhang, Qiong and Pausata, Francesco Salvatore R. and Werner, Martin and Heinecke, Liv and Kuessner, Marie L. and Feakins, Sarah J. and Sachse, Dirk and Mischke, Steffen}, title = {Hydroclimate in the Pamirs Was Driven by Changes in Precipitation-Evaporation Seasonality Since theLast Glacial Period}, series = {Geophysical research letters}, volume = {46}, journal = {Geophysical research letters}, number = {23}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0094-8276}, doi = {10.1029/2019GL085202}, pages = {13972 -- 13983}, year = {2019}, abstract = {The Central Asian Pamir Mountains (Pamirs) are a high-altitude region sensitive to climatic change, with only few paleoclimatic records available. To examine the glacial-interglacial hydrological changes in the region, we analyzed the geochemical parameters of a 31-kyr record from Lake Karakul and performed a set of experiments with climate models to interpret the results. delta D values of terrestrial biomarkers showed insolation-driven trends reflecting major shifts of water vapor sources. For aquatic biomarkers, positive delta D shifts driven by changes in precipitation seasonality were observed at ca. 31-30, 28-26, and 17-14 kyr BP. Multiproxy paleoecological data and modelling results suggest that increased water availability, induced by decreased summer evaporation, triggered higher lake levels during those episodes, possibly synchronous to northern hemispheric rapid climate events. We conclude that seasonal changes in precipitation-evaporation balance significantly influenced the hydrological state of a large waterbody such as Lake Karakul, while annual precipitation amount and inflows remained fairly constant.}, language = {en} } @article{MarkowskaFohlmeisterTrebleetal.2019, author = {Markowska, Monika and Fohlmeister, Jens Bernd and Treble, Pauline C. and Baker, Andy and Andersen, Martin S. and Hua, Quan}, title = {Modelling the C-14 bomb-pulse in young speleothems using a soil carbon continuum model}, series = {Geochimica et cosmochimica acta : journal of the Geochemical Society and the Meteoritical Society}, volume = {261}, journal = {Geochimica et cosmochimica acta : journal of the Geochemical Society and the Meteoritical Society}, publisher = {Elsevier}, address = {Oxford}, issn = {0016-7037}, doi = {10.1016/j.gca.2019.04.029}, pages = {342 -- 367}, year = {2019}, abstract = {The 'bomb-pulse' method is a chronological approach to further constrain the age of speleothems that grew between 1950 CE - present. Establishing dependable chronological constraints is crucial for modern calibration studies of speleothems to instrumental climate records, which provides the basis for paleoclimate interpretations. However, a large unknown is how 14C is transferred from the atmosphere to any individual speleothem owing to the site-specific residence times of organic matter above cave systems. Here, we employ the bomb-pulse method to build chronologies from 14C measurements in combination with a new unsaturated zone C model which considers C decomposition as a continuum, to better understand unsaturated zone 14C dynamics. The bomb-pulse curves of eight speleothems from southern Australia in three contrasting climatic regions; the semi-arid Wellington Caves site, the mediterranean Golgotha Cave site and the montane Yarrangobilly Caves site, are investigated. Overall, the modelled 14C bomb-pulse curves produce excellent fits with measured 14C speleothem data (r2 = 0.82-0.99). The C modelling reveals that unsaturated zone C is predominately young at the semi-arid site, with a weighted-mean residence time of 32 years and that tree root respiration is likely an important source of vadose CO2. At the montane site, ∼39\% of C is young (<1 years), but the weighted-mean C ages are older (145-220 years). The mediterranean site has very little contribution from young C (<12\%: 0-1 years), with weighted-mean ages between 157 and 245 years, likely due to greater adsorption of organic matter in the upper vadose zone during matrix flow, and remobilisation of C from young syngenetic karst. New end members for low speleothem Dead Carbon Proportion (DCP) are identified (2.19\% and 1.65\%, respectively) for Australian montane and semi-arid zone speleothems, where oversupply of modern CO2 in the vadose zone leads to lower DCP. It is also demonstrated that DCP can be quite variable over small time scales, that processes may be difficult to untangle and a constant DCP assumption is likely invalid. DCP variability over time is mainly controlled by the changes vadose zone CO2, where vegetation regeneration, wild-fires and karst hydrology play an important role.}, language = {en} } @article{SaltikoffFriedrichSoderholmetal.2019, author = {Saltikoff, Elena and Friedrich, Katja and Soderholm, Joshua and Lengfeld, Katharina and Nelson, Brian and Becker, Andreas and Hollmann, Rainer and Urban, Bernard and Heistermann, Maik and Tassone, Caterina}, title = {An Overview of Using Weather Radar for Climatological Studies: Successes, Challenges, and Potential}, series = {Bulletin of the American Meteorological Society}, volume = {100}, journal = {Bulletin of the American Meteorological Society}, number = {9}, publisher = {American Meteorological Soc.}, address = {Boston}, issn = {0003-0007}, doi = {10.1175/BAMS-D-18-0166.1}, pages = {1739 -- 1751}, year = {2019}, abstract = {Weather radars have been widely used to detect and quantify precipitation and nowcast severe weather for more than 50 years. Operational weather radars generate huge three-dimensional datasets that can accumulate to terabytes per day. So it is essential to review what can be done with existing vast amounts of data, and how we should manage the present datasets for the future climatologists. All weather radars provide the reflectivity factor, and this is the main parameter to be archived. Saving reflectivity as volumetric data in the original spherical coordinates allows for studies of the three-dimensional structure of precipitation, which can be applied to understand a number of processes, for example, analyzing hail or thunderstorm modes. Doppler velocity and polarimetric moments also have numerous applications for climate studies, for example, quality improvement of reflectivity and rain rate retrievals, and for interrogating microphysical and dynamical processes. However, observational data alone are not useful if they are not accompanied by sufficient metadata. Since the lifetime of a radar ranges between 10 and 20 years, instruments are typically replaced or upgraded during climatologically relevant time periods. As a result, present metadata often do not apply to past data. This paper outlines the work of the Radar Task Team set by the Atmospheric Observation Panel for Climate (AOPC) and summarizes results from a recent survey on the existence and availability of long time series. We also provide recommendations for archiving current and future data and examples of climatological studies in which radar data have already been used.}, language = {en} } @article{HudsonBotzenAerts2019, author = {Hudson, Paul and Botzen, W. J. Wouter and Aerts, Jeroen C. J. H.}, title = {Flood insurance arrangements in the European Union for future flood risk under climate and socioeconomic change}, series = {Global environmental change : human and policy dimensions}, volume = {58}, journal = {Global environmental change : human and policy dimensions}, publisher = {Elsevier}, address = {Oxford}, issn = {0959-3780}, doi = {10.1016/j.gloenvcha.2019.101966}, pages = {13}, year = {2019}, abstract = {Flood risk will increase in many areas around the world due to climate change and increase in economic exposure. This implies that adequate flood insurance schemes are needed to adapt to increasing flood risk and to minimise welfare losses for households in flood-prone areas. Flood insurance markets may need reform to offer sufficient and affordable financial protection and incentives for risk reduction. Here, we present the results of a study that aims to evaluate the ability of flood insurance arrangements in Europe to cope with trends in flood risk, using criteria that encompass common elements of the policy debate on flood insurance reform. We show that the average risk-based flood insurance premium could double between 2015 and 2055 in the absence of more risk reduction by households exposed to flooding. We show that part of the expected future increase in flood risk could be limited by flood insurance mechanisms that better incentivise risk reduction by policyholders, which lowers vulnerability. The affordability of flood insurance can be improved by introducing the key features of public-private partnerships (PPPs), which include public reinsurance, limited premium cross-subsidisation between low- and high-risk households, and incentives for policyholder-level risk reduction. These findings were evaluated in a comprehensive sensitivity analysis and support ongoing reforms in Europe and abroad that move towards risk-based premiums and link insurance with risk reduction, strengthen purchase requirements, and engage in multi-stakeholder partnerships.}, language = {en} } @article{KornherKalkuhl2019, author = {Kornher, Lukas and Kalkuhl, Matthias}, title = {The gains of coordination - When does regional cooperation for food security make sense?}, series = {Global Food Security - AGRICULTURE POLICY ECONOMICS AND ENVIRONMENT}, volume = {22}, journal = {Global Food Security - AGRICULTURE POLICY ECONOMICS AND ENVIRONMENT}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2211-9124}, doi = {10.1016/j.gfs.2019.09.004}, pages = {37 -- 45}, year = {2019}, abstract = {With the onset of the global food crisis, the discussion about the use and misuse of agricultural market interventions regained academic attention. As a result of economies of scale, centralized policy implementation at the regional level has the potential to reduce the budgetary costs of policies. Borrowing from the literature on international unions and international policy coordination, we develop a conceptual framework to analyze when regional policy implementation makes sense. This is the case whenever spill-overs from centralization are large and policy preferences, driven by country-specific characteristics, are homogeneous. Subsequently, we examine the advantageousness of centralized policy implementation for the West African region regarding the most common food security policies. We show that centralization of trade policies and emergency food reserves is beneficial, while buffer stocks, safety net policies, and producer support policies should be implemented at the national level.}, language = {en} } @article{MargirierBraunGautheronetal.2019, author = {Margirier, Audrey and Braun, Jean and Gautheron, Cecile and Carcaillet, Julien and Schwartz, Stephane and Jamme, Rosella Pinna and Stanley, Jessica}, title = {Climate control on Early Cenozoic denudation of the Namibian margin as deduced from new thermochronological constraints}, series = {Earth \& planetary science letters}, volume = {527}, journal = {Earth \& planetary science letters}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0012-821X}, doi = {10.1016/j.epsl.2019.115779}, pages = {11}, year = {2019}, abstract = {The processes that control long term landscape evolution in continental interiors and, in particular, along passive margins such as in southern Africa, are still the subject of much debate (e.g. Braun, 2018). Although today the Namibian margin is characterized by an arid climate, it has experienced climatic fluctuations during the Cenozoic and, yet, to date no study has documented the potential role of climate on its erosion history. In western Namibia, the Brandberg Massif, an erosional remnant or inselberg, provides a good opportunity to document the Cenozoic denudation history of the margin using the relationship between rock cooling or exhumation ages and their elevation. Here we provide new apatite (UThSm)/He dates on the Brandberg Inselberg that range from 151 +/- 12 to 30 +/- 2 Ma. Combined with existing apatite fission track data, they yield new constraints on the denudation history of the margin. These data document two main cooling phases since continental break-up 130 Myr ago, a rapid one (similar to 10 degrees C/Myr) following break-up and a slower one (similar to 12 degrees C/Myr) between 65 and 35 Ma. We interpret them respectively to be related to escarpment erosion following rifting and continental break-up and as a phase of enhanced denudation during the Early Eocene Climatic Optimum. We propose that during the Early Eocene Climatic Optimum chemical weathering was important and contributed significantly to the denudation of the Namibian margin and the formation of a pediplain around the Brandberg and enhanced valley incision within the massif. Additionally, aridification of the region since 35 Ma has resulted in negligible denudation rates since that time. (C) 2019 Elsevier B.V. All rights reserved.}, language = {en} } @article{PenaHeidbachMorenoetal.2019, author = {Pena, Carlos and Heidbach, Oliver and Moreno, Marcos and Bedford, Jonathan and Ziegler, Moritz 0. and Tassara, Andres Ollero and Oncken, Onno}, title = {Role of Lower Crust in the Postseismic Deformation of the 2010 Maule Earthquake: Insights from a Model with Power-Law Rheology}, series = {Pure and applied geophysics}, volume = {176}, journal = {Pure and applied geophysics}, number = {9}, publisher = {Springer}, address = {Basel}, issn = {0033-4553}, doi = {10.1007/s00024-018-02090-3}, pages = {3913 -- 3928}, year = {2019}, abstract = {The surface deformation associated with the 2010 M-w 8.8 Maule earthquake in Chile was recorded in great detail before, during and after the event. The high data quality of the continuous GPS (cGPS) observations has facilitated a number of studies that model the postseismic deformation signal with a combination of relocking, afterslip and viscoelastic relaxation using linear rheology for the upper mantle. Here, we investigate the impact of using linear Maxwell or power-law rheology with a 2D geomechanical-numerical model to better understand the relative importance of the different processes that control the postseismic deformation signal. Our model results reveal that, in particular, the modeled cumulative vertical postseismic deformation pattern in the near field (< 300 km from the trench) is very sensitive to the location of maximum afterslip and choice of rheology. In the model with power-law rheology, the afterslip maximum is located at 20-35 km rather than > 50 km depth as suggested in previous studies. The explanation for this difference is that in the model with power-law rheology the relaxation of coseismically imposed differential stresses occurs mainly in the lower crust. However, even though the model with power-law rheology probably has more potential to explain the vertical postseismic signal in the near field, the uncertainty of the applied temperature field is substantial, and this needs further investigations and improvements.}, language = {en} } @article{FosterLehrmannYuetal.2019, author = {Foster, William J. and Lehrmann, Daniel J. and Yu, Meiyi and Martindale, Rowan C.}, title = {Facies selectivity of benthic invertebrates in a Permian/Triassic boundary microbialite succession: Implications for the "microbialite refuge" hypothesis}, series = {Geobiology}, volume = {17}, journal = {Geobiology}, number = {5}, publisher = {Wiley}, address = {Hoboken}, issn = {1472-4677}, doi = {10.1111/gbi.12343}, pages = {523 -- 535}, year = {2019}, abstract = {Thrombolite and stromatolite habitats are becoming increasingly recognized as important refuges for invertebrates during Phanerozoic Oceanic Anoxic Events (OAEs); it is posited that oxygenic photosynthesis by cyanobacteria in these microbialites provided a refuge from anoxic conditions (i.e., the "microbialite refuge" hypothesis). Here, we test this hypothesis by investigating the distribution of ~34, 500 benthic invertebrate fossils found in ~100 samples from a microbialite succession that developed following the latest Permian mass extinction event on the Great Bank of Guizhou (South China), representing microbial (stromatolites and thrombolites) and non-microbial facies. The stromatolites were the least taxonomically diverse facies, and the thrombolites also recorded significantly lower diversities when compared to the non-microbial facies. Based on the distribution and ornamentation of the bioclasts within the thrombolites and stromatolites, the bioclasts are inferred to have been transported and concentrated in the non-microbial fabrics, that is, cavities around the microbial framework. Therefore, many of the identified metazoans from the post-extinction microbialites are not observed to have been living within a microbial mat. Furthermore, the lifestyle of many of the taxa identified from the microbialites was not suited for, or even amenable to, life within a benthic microbial mat. The high diversity of oxygen-dependent metazoans in the non-microbial facies on the Great Bank of Guizhou, and inferences from geochemical records, suggests that the microbialites and benthic communities developed in oxygenated environments, which disproves that the microbes were the source of the oxygenation. Instead, we posit that microbialite successions represent a taphonomic window for exceptional preservation of the biota, similar to a Konzentrat-Lagerstatte, which has allowed for diverse fossil assemblages to be preserved during intervals of poor preservation.}, language = {en} } @article{WenzlaffWinterleitnerSchutz2019, author = {Wenzlaff, Christian and Winterleitner, Gerd and Schutz, Felina}, title = {Controlling parameters of a mono-well high-temperature aquifer thermal energy storage in porous media, northern Oman}, series = {Petroleum geoscience}, volume = {25}, journal = {Petroleum geoscience}, number = {3}, publisher = {Geological Soc. Publ. House}, address = {Bath}, issn = {1354-0793}, doi = {10.1144/petgeo2018-104}, pages = {337 -- 349}, year = {2019}, abstract = {Aquifer thermal energy storage (ATES) as a complement to fluctuating renewable energy systems is a reliable technology to guarantee continuous energy supply for heating and air conditioning. We investigated a high-temperature (HT) mono-well system (c. 100 degrees C), where the well screens are separated vertically within the aquifer, as an alternative to conventional doublet ATES systems for an underground storage in northern Oman. We analysed the impact of thermal inference between injection and extraction well screens on the heat recovery factor (HRF) in order to define the optimal screento-screen distance for best possible systems efficiency. Two controlling interference parameters were considered: the vertical screen-to-screen distance and aquifer heterogeneities. The sensitivity study shows that with decreasing screen-to-screen distances, thermal interference increases storage performance. A turning point is reached if the screen distance is too close, causing either water breakthrough or negative thermal interference between the screens. Our simulations show that a combined heat plume with spherical geometry results in the highest heat recovery factors due to the lowest surface area to volume ratios. Thick aquifers for mono-well HT-ATES are thus not mandatory Our study shows that a HT-ATES mono-well system is a feasible storage design with high heat recovery factors for continuous cooling or heating purposes.}, language = {en} } @article{CerantolaWilkeKantoretal.2019, author = {Cerantola, Valerio and Wilke, Max and Kantor, Innokenty and Ismailova, Leyla and Kupenko, Ilya and McCammon, Catherine and Pascarelli, Sakura and Dubrovinsky, Leonid S.}, title = {Experimental investigation of FeCO3 (siderite) stability in Earth's lower mantle using XANES spectroscopy}, series = {American mineralogist : an international journal of earth and planetary materials}, volume = {104}, journal = {American mineralogist : an international journal of earth and planetary materials}, number = {8}, publisher = {Mineralogical Society of America}, address = {Chantilly}, issn = {0003-004X}, doi = {10.2138/am-2019-6428}, pages = {1083 -- 1091}, year = {2019}, abstract = {We studied FeCO3 using Fe K-edge X-ray absorption near-edge structure (XANES) spectroscopy at pressures up to 54 GPa and temperatures above 2000 K. First-principles calculations of Fe at the K-edge in FeCO3 were performed to support the interpretation of the XANES spectra. The variation of iron absorption edge features with pressure and temperature in FeCO3 matches well with recently reported observations on FeCO3 at extreme conditions, and provides new insight into the stability of Fe-carbonates in Earth's mantle. Here we show that at conditions of the mid-lower mantle, ~50 GPa and ~2200 K, FeCO3 melts and partially decomposes to high-pressure Fe3O4. Carbon (diamond) and oxygen are also inferred products of the reaction. We constrained the thermodynamic phase boundary between crystalline FeCO3 and melt to be at 51(1) GPa and ~1850 K. We observe that at 54(1) GPa, temperature-induced spin crossover of Fe2+ takes place from low to high spin such that at 1735(100) K, all iron in FeCO3 is in the high-spin state. A comparison between experiment and theory provides a more detailed understanding of FeCO3 decomposition observed in X-ray absorption spectra and helps to explain spectral changes due to pressure-induced spin crossover in FeCO3 at ambient temperature.}, language = {en} } @article{LeonCardonaMejiaVelezetal.2019, author = {Le{\´o}n, Santiago and Cardona, Agust{\´i}n and Mejia Velez, Dany and Botello, G. E. and Villa, V{\´i}ctor and Collo, Gilda and Valencia, Victor A. and Zapata, Sebastian Henao and Avellaneda-Jimenez, D. S.}, title = {Source area evolution and thermal record of an Early Cretaceous back-arc basin along the northwesternmost Colombian Andes}, series = {Journal of South American earth sciences}, volume = {94}, journal = {Journal of South American earth sciences}, publisher = {Elsevier}, address = {Oxford}, issn = {0895-9811}, doi = {10.1016/j.jsames.2019.102229}, pages = {16}, year = {2019}, abstract = {Identifying the provenance signature and geodynamic setting on which sedimentary basins at convergent margins grow is challenging since they result from coupled erosional and tectonic processes, which shape the evolution of source areas and the stress regime. The Early Cretaceous evolution of the northern Andes of Colombia is characterized by extensional tectonics and the subsequent formation of a marginal basin. The Abejorral Formation and coeval volcano-sedimentary rocks are exposed along the western flank and axis of the Central Cordillera. They comprise an Early Cretaceous transgressive sequence initially accumulated in fluvial deltaic environments, which switched towards a deep-marine setting, and are interpreted as the infilling record of a marginal back-arc basin. Available provenance data suggest that Permian-Triassic metamorphic and less abundant Jurassic magmatic rocks forming the basement of the Central Cordillera sourced the Abejorral Formation. New detailed volcanic and metamorphic lithics analyses, conventional and varietal study of heavy minerals, detrital rutile mineral chemistry, allowed us to document changes in the source areas defined by the progressive appearance of both higher-grade and more distal low-grade metamorphic sources, which switched from pelitic to dominantly mafic in composition. Crystallochemical indexes of clay minerals of fine-grained rocks of the Abejorral Formation suggest that samples located close to the Romeral Fault System show characteristics of low-medium P-T low-grade metamorphism, whereas rocks located farther to the northeast preserve primary diagenetic features, which suggest a high heat-flow accumulation setting. We interpret that the Abejorral Formation records the progressive unroofing of the Central Cordillera basement that was being rapidly exhumed, as well as the incorporation of distal subduction-related metamorphic complexes to the west in response either to the widening of extensional front or the reactivation of fault structures on the oceanward margin of the basin. Although the deformational record of the Abejorral Formation would have resulted from over-imposed episodes, our new geochronological constraints suggest that this sedimentary sequence must have been deformed before the Paleocene due to the presence of arc-related intrusive non-deformed magmatic rocks with a crystallization age of ca. 60 Ma.}, language = {en} } @article{Iturrizaga2019, author = {Iturrizaga, Lasafam}, title = {Historical beacon fire lines as early warning systems for glacier lake outbursts in the Hindu Kush-Karakoram Mountains}, series = {Natural hazards : journal of the International Society for the Prevention and Mitigation of Natural Hazards}, volume = {99}, journal = {Natural hazards : journal of the International Society for the Prevention and Mitigation of Natural Hazards}, number = {1}, publisher = {Springer}, address = {New York}, issn = {0921-030X}, doi = {10.1007/s11069-019-03705-1}, pages = {39 -- 70}, year = {2019}, abstract = {The paper presents a historical long-distance communication system based on beacon fires in one of the most dynamic and rugged mountain ranges of the world, the Hindu Kush-Karakoram-Himalayas. It was deployed as an early warning system for glacial lake outburst floods, which caused devastating impacts on settlement zones and infrastructure until the middle of the twentieth century. The study revealed that the beacon fire systems were operated in distinct valleys spread over the entire Hindu Kush-Karakoram Region. The remarkable fact is the establishment of fire posts in highly difficult accessible mountain environments with communication distances of several hundred kilometres for individual beacon lines. The warning system was a cooperative natural hazard management, which was operated even across distinct ethnic groups. Distant societies, formerly perceived as isolated villages by physical barriers of the high mountain relief, were in historical times connected not only by challenging trade routes but also by a fast working optical communication system. The findings are discussed in the context of a future sustainable natural hazard management.}, language = {en} } @article{McKibbinPittarelloMakaronaetal.2019, author = {McKibbin, Seann J. and Pittarello, Lidia and Makarona, Christina and Hamann, Christopher and Hecht, Lutz and Chernonozhkin, Stepan M. and Goderis, Steven and Claeys, Philippe}, title = {Petrogenesis of main group pallasite meteorites based on relationships among texture, mineralogy, and geochemistry}, series = {Meteoritics \& planetary science : journal of the Meteoritical Society}, volume = {54}, journal = {Meteoritics \& planetary science : journal of the Meteoritical Society}, number = {11}, publisher = {Wiley}, address = {Hoboken}, issn = {1086-9379}, doi = {10.1111/maps.13392}, pages = {2814 -- 2844}, year = {2019}, abstract = {Main group pallasite meteorites are samples of a single early magmatic planetesimal, dominated by metal and olivine but containing accessory chromite, sulfide, phosphide, phosphates, and rare phosphoran olivine. They represent mixtures of core and mantle materials, but the environment of formation is poorly understood, with a quiescent core-mantle boundary, violent core-mantle mixture, or surface mixture all recently suggested. Here, we review main group pallasite data sets and petrologic characteristics, and present new observations on the low-MnO pallasite Brahin that contains abundant fragmental olivine, but also rounded and angular olivine and potential evidence of sulfide-phosphide liquid immiscibility. A reassessment of the literature shows that low-MnO and high-FeO subgroups preferentially host rounded olivine and low-temperature P2O5-rich phases such as the Mg-phosphate farringtonite and phosphoran olivine. These phases form after metal and silicate reservoirs back-react during decreasing temperature after initial separation, resulting in oxidation of phosphorus and chromium. Farringtonite and phosphoran olivine have not been found in the common subgroup PMG, which are mechanical mixtures of olivine, chromite with moderate Al2O3 contents, primitive solid metal, and evolved liquid metal. Lower concentrations of Mn in olivine of the low-MnO PMG subgroup, and high concentrations of Mn in low-Al2O3 chromites, trace the development and escape of sulfide-rich melt in pallasites and the partially chalcophile behavior for Mn in this environment. Pallasites with rounded olivine indicate that the core-mantle boundary of their planetesimal may not be a simple interface but rather a volume in which interactions between metal, silicate, and other components occur.}, language = {en} } @article{LescoutreTugendBruneetal.2019, author = {Lescoutre, Rodolphe and Tugend, Julie and Brune, Sascha and Masini, Emmanuel and Manatschal, Gianreto}, title = {Thermal Evolution of Asymmetric Hyperextended Magma-Poor Rift Systems: Results From Numerical Modeling and Pyrenean Field Observations}, series = {Geochemistry, geophysics, geosystems}, volume = {20}, journal = {Geochemistry, geophysics, geosystems}, number = {10}, publisher = {American Geophysical Union}, address = {Washington}, issn = {1525-2027}, doi = {10.1029/2019GC008600}, pages = {4567 -- 4587}, year = {2019}, abstract = {We investigate the thermal and structural evolution of asymmetric rifted margin using numerical modeling and geological observations derived from the Western Pyrenees. Our numerical model provides a self-consistent physical evolution of the top basement heat flow during asymmetric rifting. The model shows a pronounced thermal asymmetry that is caused by migration of the rift center toward the upper plate. The same process creates a diachronism for the record of maximum heat flow and maximum temperatures (T-max) in basal rift sequences. The Mauleon-Arzacq basin (W-Pyrenees) corresponds to a former mid-Cretaceous asymmetric hyperextended rift basin. New vitrinite reflectance data in addition to existing data sets from this basin reveal an asymmetry in the distribution of peak heat (T-max) with respect to the rift shoulders, where highest values are located at the former upper- to lower-plate transition. This data set from the Arzacq-Mauleon field study confirms for the first time the thermal asymmetry predicted by numerical models. Numerical modeling results also suggest that complexities in synrift thermal architecture could arise when hanging-wall-derived extensional allochthons and related T-max become part of the lower plate and are transported away from the upper- to lower-plate transition. This study emphasizes the limitations of the common approach to integrate punctual thermal data from pre-rift to synrift sedimentary sequences in order to describe the rift-related thermal evolution and paleothermal gradients at the scale of a rift basin or a rifted margin.}, language = {en} } @article{WalterLueckHelleretal.2019, author = {Walter, J. and L{\"u}ck, Erika and Heller, C. and Bauriegel, Albrecht and Zeitz, Jutta}, title = {Relationship between electrical conductivity and water content of peat and gyttja}, series = {Near surface geophysics}, volume = {17}, journal = {Near surface geophysics}, number = {2}, publisher = {Wiley}, address = {Hoboken}, issn = {1569-4445}, doi = {10.1002/nsg.12030}, pages = {169 -- 179}, year = {2019}, abstract = {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.}, language = {en} } @article{AngelopoulosWestermannOverduinetal.2019, author = {Angelopoulos, Michael and Westermann, Sebastian and Overduin, Pier Paul and Faguet, Alexey and Olenchenko, Vladimir and Grosse, Guido and Grigoriev, Mikhail N.}, title = {Heat and salt flow in subsea permafrost modeled with CryoGRID2}, series = {Journal of geophysical research : Earth surface}, volume = {124}, journal = {Journal of geophysical research : Earth surface}, number = {4}, publisher = {American Geophysical Union}, address = {Hoboken}, issn = {2169-9003}, doi = {10.1029/2018JF004823}, pages = {920 -- 937}, year = {2019}, abstract = {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.}, language = {en} } @article{BenDorNeugebauerEnzeletal.2019, author = {Ben Dor, Yoav and Neugebauer, Ina and Enzel, Yehouda and Schwab, Markus Julius and Tjallingii, Rik and Erel, Yigal and Brauer, Achim}, title = {Varves of the Dead Sea sedimentary record}, series = {Quaternary science reviews : the international multidisciplinary research and review journal}, volume = {215}, journal = {Quaternary science reviews : the international multidisciplinary research and review journal}, publisher = {Elsevier}, address = {Oxford}, issn = {0277-3791}, doi = {10.1016/j.quascirev.2019.04.011}, pages = {173 -- 184}, year = {2019}, abstract = {The sedimentary record of the Dead Sea provides an exceptional high-resolution archive of past climate changes in the drought-sensitive eastern Mediterranean-Levant, a key region for the development of humankind at the boundary of global climate belts. Moreover, it is the only deep hypersaline lake known to have deposited long sequences of finely laminated, annually deposited sediments (i.e. varves) of varied compositions, including aragonite, gypsum, halite and clastic sediments. Vast efforts have been made over the years to decipher the environmental information stored in these evaporitic-clastic sequences spanning from the Pleistocene Lake Amora to the Holocene Dead Sea. A general characterisation of sediment facies has been derived from exposed sediment sections, as well as from shallow- and deep-water sediment cores. During high lake stands and episodes of positive water budget, mostly during glacial times, alternating aragonite and detritus laminae ('aad' facies) were accumulated, whereas during low lake stands and droughts, prevailing during interglacials, laminated detritus ('ld' facies) and laminated halite ('lh' facies) dominate the sequence. In this paper, we (i) review the three types of laminated sediments of the Dead Sea sedimentary record ('aad', 'ld' and 'lh' facies), (ii) discuss their modes of formation, deposition and accumulation, and their interpretation as varves, and (iii) illustrate how Dead Sea varves are utilized for palaeoclimate reconstructions and for establishing floating chronologies.}, language = {en} } @article{LatimerJacobsGianolietal.2019, author = {Latimer, Andrew M. and Jacobs, Brooke S. and Gianoli, Ernesto and Heger, Tina and Salgado-Luarte, Cristian}, title = {Parallel functional differentiation of an invasive annual plant on two continents}, series = {AoB PLANTS}, volume = {11}, journal = {AoB PLANTS}, number = {2}, publisher = {Oxford University Press}, address = {Oxford}, issn = {2041-2851}, doi = {10.1093/aobpla/plz010}, pages = {16}, year = {2019}, abstract = {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.}, language = {en} } @article{SoaresYamazakiMatzkaetal.2019, author = {Soares, Gabriel and Yamazaki, Yosuke and Matzka, J{\"u}rgen and Pinheiro, Katia and Stolle, Claudia and Alken, Patrick and Yoshikawa, Akimasa and Uozumi, Teiji and Fujimoto, Akiko and Kulkarni, Atul}, title = {Longitudinal variability of the equatorial counter electrojet during the solar cycle 24}, series = {Studia geophysica et geodaetica}, volume = {63}, journal = {Studia geophysica et geodaetica}, number = {2}, publisher = {Springer}, address = {New York}, issn = {0039-3169}, doi = {10.1007/s11200-018-0286-0}, pages = {304 -- 319}, year = {2019}, abstract = {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.}, language = {en} } @article{JavharChenBaoetal.2019, author = {Javhar, Aminov and Chen, Xi and Bao, Anming and Jamshed, Aminov and Yunus, Mamadjanov and Jovid, Aminov and Latipa, Tuerhanjiang}, title = {Comparison of Multi-Resolution Optical Landsat-8, Sentinel-2 and Radar Sentinel-1 Data for Automatic Lineament Extraction}, series = {Remote sensing}, volume = {11}, journal = {Remote sensing}, number = {7}, publisher = {MDPI}, address = {Basel}, issn = {2072-4292}, doi = {10.3390/rs11070778}, pages = {29}, year = {2019}, abstract = {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.}, language = {en} } @article{KoehnReichBuerger2019, author = {K{\"o}hn-Reich, Lisei and B{\"u}rger, Gerd}, title = {Dynamical prediction of Indian monsoon}, series = {International Journal of Climatology}, volume = {39}, journal = {International Journal of Climatology}, number = {8}, publisher = {Wiley}, address = {Hoboken}, issn = {0899-8418}, doi = {10.1002/joc.6039}, pages = {3574 -- 3581}, year = {2019}, abstract = {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.}, language = {en} } @article{EberliBernoulliVecseietal.2019, author = {Eberli, Gregor P. and Bernoulli, Daniel and Vecsei, Adam and Sekti, Rizky and Grasmueck, Mark and L{\"u}dmann, Thomas and Anselmetti, Flavio S. and Mutti, Maria and Della Porta, Giovanna}, title = {A Cretaceous carbonate delta drift in the Montagna della Maiella, Italy}, series = {Sedimentology : the journal of the International Association of Sedimentologists}, volume = {66}, journal = {Sedimentology : the journal of the International Association of Sedimentologists}, number = {4}, publisher = {Wiley}, address = {Hoboken}, issn = {0037-0746}, doi = {10.1111/sed.12590}, pages = {1266 -- 1301}, year = {2019}, abstract = {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.}, language = {en} } @article{FrijiaForknerMinisinietal.2019, author = {Frijia, Gianluca and Forkner, R. and Minisini, D. and Pacton, M. and Struck, Ulrich and Mutti, Maria}, title = {Cyanobacteria proliferation in the cenomanian-turonian boundary interval of the apennine carbonate platform:}, series = {Geochemistry, geophysics, geosystems}, volume = {20}, journal = {Geochemistry, geophysics, geosystems}, number = {6}, publisher = {American Geophysical Union}, address = {Washington}, issn = {1525-2027}, doi = {10.1029/2019GC008306}, pages = {2698 -- 2716}, year = {2019}, abstract = {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.}, language = {en} } @article{RiechelmanFohlmeisterKlugeetal.2019, author = {Riechelman, Dana F. C. and Fohlmeister, Jens Bernd and Kluge, Tobias and Jochum, Klaus Peter and Richter, Detlev K. and Deininger, Michael and Friedrich, Ronny and Frank, Norbert and Scholz, Denis}, title = {Evaluating the potential of tree-ring methodology for cross-dating of three annually laminated stalagmites from Zoolithencave (SE Germany)}, series = {Quaternary geochronology : the international research and review journal on advances in quaternary dating techniques}, volume = {52}, journal = {Quaternary geochronology : the international research and review journal on advances in quaternary dating techniques}, publisher = {Elsevier}, address = {Oxford}, issn = {1871-1014}, doi = {10.1016/j.quageo.2019.04.001}, pages = {37 -- 50}, year = {2019}, abstract = {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).}, language = {en} } @article{WalzSchmidtRuizFrauetal.2019, author = {Walz, Ariane and Schmidt, Katja and Ruiz-Frau, Ana and Nicholas, Kimberly A. and Bierry, Adeline and Lentsch, Aster de Vries and Dyankov, Apostol and Joyce, Deirdre and Liski, Anja H. and Marba, Nuria and Rosario, Ines T. and Scholte, Samantha S. K.}, title = {Sociocultural valuation of ecosystem services for operational ecosystem management: mapping applications by decision contexts in Europe}, series = {Regional environmental change}, volume = {19}, journal = {Regional environmental change}, number = {8}, publisher = {Springer}, address = {Heidelberg}, issn = {1436-3798}, doi = {10.1007/s10113-019-01506-7}, pages = {2245 -- 2259}, year = {2019}, abstract = {Sociocultural valuation (SCV) of ecosystem services (ES) discloses the principles, importance or preferences expressed by people towards nature. Although ES research has increasingly addressed sociocultural values in past years, little effort has been made to systematically review the components of sociocultural valuation applications for different decision contexts (i.e. awareness raising, accounting, priority setting, litigation and instrument design). In this analysis, we investigate the characteristics of 48 different sociocultural valuation applications—characterised by unique combinations of decision context, methods, data collection formats and participants—across ten European case studies. Our findings show that raising awareness for the sociocultural value of ES by capturing people's perspective and establishing the status quo, was found the most frequent decision context in case studies, followed by priority setting and instrument development. Accounting and litigation issues were not addressed in any of the applications. We reveal that applications for particular decision contexts are methodologically similar, and that decision contexts determine the choice of methods, data collection formats and participants involved. Therefore, we conclude that understanding the decision context is a critical first step to designing and carrying out fit-for-purpose sociocultural valuation of ES in operational ecosystem management.}, language = {en} } @article{KaercherFrankWalzetal.2019, author = {K{\"a}rcher, Oskar and Frank, Karin and Walz, Ariane and Markovic, Danijela}, title = {Scale effects on the performance of niche-based models of freshwater fish distributions}, series = {Ecological modelling : international journal on ecological modelling and engineering and systems ecolog}, volume = {405}, journal = {Ecological modelling : international journal on ecological modelling and engineering and systems ecolog}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0304-3800}, doi = {10.1016/j.ecolmodel.2019.05.006}, pages = {33 -- 42}, year = {2019}, abstract = {Niche-based species distribution models (SDMs) have become an essential tool in conservation and restoration planning. Given the current threats to freshwater biodiversity, it is of fundamental importance to address scale effects on the performance of niche-based SDMs of freshwater species' distributions. The scale effects are addressed here in the context of hierarchical catchment ordering, considered as counterpart to coarsening grain-size by increasing grid-cell size. We combine fish occurrence data from the Danube River Basin, the hierarchical catchment ordering and multiple environmental factors representing topographic, climatic and anthropogenic effects to model fish occurrence probability across multiple scales. We focus on 1st to 5th order catchments. The spatial scale (hierarchical catchment order) only marginally influences the mean performance of SDMs, however the uncertainty of the estimates increases with scale. Key predictors and their relative importance are scale and species dependent. Our findings have useful implications for choosing proper species dependent spatial scales for river rehabilitation measures, and for conservation planning in areas where fine grain species data are unavailable.}, language = {en} } @article{SheikholeslamiOberhaensliGhassemi2019, author = {Sheikholeslami, Mohammad Reza and Oberh{\"a}nsli, Roland and Ghassemi, Mohammad R.}, title = {Transpression tectonics in the eastern Binalud Mountains, northeast Iran; Insight from finite strain analysis, vorticity and Ar-40/Ar-39 dating}, series = {Journal of Asian earth sciences}, volume = {179}, journal = {Journal of Asian earth sciences}, publisher = {Elsevier}, address = {Oxford}, issn = {1367-9120}, doi = {10.1016/j.jseaes.2019.04.014}, pages = {219 -- 237}, year = {2019}, abstract = {Different tectonic episodes from Late Triassic to recent times in the eastern Binalud Mountains have resulted from convergence and transpression between the Turan and Central Iran plates. Heterogeneous deformation and variable portions of pure and simple shear, demonstrated by finite strain and vorticity analysis in the Mashhad metamorphic rocks, indicate strain partitioning during the first tectonic episode. Modern strain partitioning is characterized by reverse and strike-slip faulting along the Neyshabur fault system and Shandiz fault zone in the southern and northern flanks of the eastern Binalud, respectively. Time-transgressive regional deformation migrated from the hinterland of the belt into the foreland basin, from northeast to the southwest of the mountains. Different generations of deformation resulted in obliteration of the subduction-related accretionary wedge, and growth of an orogenic wedge resulted from collision between the Central Iran and Turan plates.}, language = {en} } @article{MerzLischeid2019, author = {Merz, Christoph and Lischeid, Gunnar}, title = {Multivariate analysis to assess the impact of irrigation on groundwater quality}, series = {Environmental earth sciences}, volume = {78}, journal = {Environmental earth sciences}, number = {274}, publisher = {Springer}, address = {New York}, issn = {1866-6280}, doi = {10.1007/s12665-019-8274-4}, pages = {11}, year = {2019}, abstract = {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.}, language = {en} } @article{PetersenCescaKriegerowski2019, author = {Petersen, Gesa Maria and Cesca, Simone and Kriegerowski, Marius}, title = {Automated quality control for large seismic networks}, series = {Seismological research letters}, volume = {90}, journal = {Seismological research letters}, number = {3}, publisher = {Seismological Society of America}, address = {Albany}, organization = {AlpArray Working Grp}, issn = {0895-0695}, doi = {10.1785/0220180342}, pages = {1177 -- 1190}, year = {2019}, abstract = {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.}, language = {en} } @article{KaufmannHoffmannBachmannetal.2019, author = {Kaufmann, Felix E. D. and Hoffmann, Marie C. and Bachmann, Kai and Veksler, Ilya V. and Trumbull, Robert B. and Hecht, Lutz}, title = {Variations in Composition, Texture, and Platinum Group Element Mineralization in the Lower Group and Middle Group Chromitites of the Northwestern Bushveld Complex, South Africa}, series = {Economic geology}, volume = {114}, journal = {Economic geology}, number = {3}, publisher = {The Economic Geology Publ. Co}, address = {Littleton}, issn = {0361-0128}, doi = {10.5382/econgeo.4641}, pages = {569 -- 590}, year = {2019}, abstract = {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.}, language = {en} } @article{vanderMeijReimannVornehmetal.2019, author = {van der Meij, Marijn W. and Reimann, Tony and Vornehm, V. K. and Temme, Arnaud J. A. M. and Wallinga, Jakob and van Beek, Roy and Sommer, Michael}, title = {Reconstructing rates and patterns of colluvial soil redistribution in agrarian (hummocky) landscapes}, series = {Earth surface processes and landforms : the journal of the British Geomorphological Research Group}, volume = {44}, journal = {Earth surface processes and landforms : the journal of the British Geomorphological Research Group}, number = {12}, publisher = {Wiley}, address = {Hoboken}, issn = {0197-9337}, doi = {10.1002/esp.4671}, pages = {2408 -- 2422}, year = {2019}, abstract = {Humans have triggered or accelerated erosion processes since prehistoric times through agricultural practices. Optically stimulated luminescence (OSL) is widely used to quantify phases and rates of the corresponding landscape change, by measuring the last moment of daylight exposure of sediments. However, natural and anthropogenic mixing processes, such as bioturbation and tillage, complicate the use of OSL as grains of different depositional ages become mixed, and grains become exposed to light even long after the depositional event of interest. Instead, OSL determines the stabilization age, indicating when sediments were buried below the active mixing zone. These stabilization ages can cause systematic underestimation when calculating deposition rates. Our focus is on colluvial deposition in a kettle hole in the Uckermark region, northeastern Germany. We took 32 samples from five locations in the colluvium filling the kettle hole to study both spatial and temporal patterns in colluviation. We combined OSL dating with advanced age modelling to determine the stabilization age of colluvial sediments. These ages were combined with an archaeological reconstruction of historical ploughing depths to derive the levels of the soil surface at the moment of stabilization; the deposition depths, which were then used to calculate unbiased deposition rates. We identified two phases of colluvial deposition. The oldest deposits (similar to 5 ka) were located at the fringe of the kettle hole and accumulated relatively slowly, whereas the youngest deposits (<0.3 ka) rapidly filled the central kettle hole with rates of two orders of magnitude higher. We suggest that the latter phase is related to artificial drainage, facilitating accessibility in the central depression for agricultural practices. Our results show the need for numerical dating techniques that take archaeological and soil-geomorphological information into account to identify spatiotemporal patterns of landscape change, and to correctly interpret landscape dynamics in anthropogenically influenced hilly landscapes. (c) 2019 The Authors. Earth Surface Processes and Landforms Published by John Wiley \& Sons Ltd.}, language = {en} } @article{MaLiKempkaetal.2019, author = {Ma, Jianli and Li, Qi and Kempka, Thomas and K{\"u}hn, Michael}, title = {Hydromechanical response and impact of gas mixing behavior in subsurface CH4 storage with CO2-based cushion gas}, series = {Energy \& fuels}, volume = {33}, journal = {Energy \& fuels}, number = {7}, publisher = {American Chemical Society}, address = {Washington}, issn = {0887-0624}, doi = {10.1021/acs.energyfuels.9b00518}, pages = {6527 -- 6541}, year = {2019}, abstract = {Power-to-gas (PtG) stores chemical energy by converting excess electrical energy from renewable sources into an energy-dense gas. Due to its higher available capacity compared to surface-based storage technologies, subsurface storage in geological systems is the most promising approach for efficient and economic realization of the PtG system's storage component. For this purpose, methane (CH4) produced by methanation by means of hydrogen (H2) and carbon dioxide (CO2) is stored in a geological reservoir until required for further use. In this context, CO2 is used as the cushion gas to maintain reservoir pressure and limiting working gas, i.e., (CH4) losses during withdrawal periods. Consequently, mixing of both gases in the reservoir is inevitable. Therefore, it is necessary to minimize the gas mixing region to optimize the efficiency of the PtG system's storage component. In the present study, the physical properties of CH4, CO2 and their mixtures are reviewed. Then, a multicomponent flow model is implemented and validated against published data. Next, a hydromechanically coupled model is established, considering fluid flow through porous media and effective stresses to investigate the mixing behavior of both gases and the mechanical reservoir stability. The simulation results show that, with increasing reservoir thickness and dip angle, the mixing region is reduced during gas injection if CO2 is employed as the cushion gas. In addition, the degree of mixing is lower at higher temperatures. Feasible injection rates and injection schedules can be derived from the integrated reservoir stability analysis. The methodology developed in the present study allows the determination of optimum strategies for storage reservoir selection and gas injection scheduling by minimizing the gas mixing region.}, language = {en} } @article{DeinoDommainKelleretal.2019, author = {Deino, A. L. and Dommain, Ren{\´e} and Keller, C. B. and Potts, R. and Behrensmeyer, A. K. and Beverly, E. J. and King, J. and Heil, C. W. and Stockhecke, M. and Brown, E. T. and Moerman, J. and deMenocal, P. and Deocampo, D. and Garcin, Yannick and Levin, N. E. and Lupien, R. and Owen, R. B. and Rabideaux, N. and Russell, J. M. and Scott, J. and Riedl, S. and Brady, K. and Bright, J. and Clark, J. B. and Cohen, A. and Faith, J. T. and Noren, A. and Muiruri, V. and Renaut, R. and Rucina, S. and Uno, K.}, title = {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}, series = {Quaternary science reviews : the international multidisciplinary research and review journal}, volume = {215}, journal = {Quaternary science reviews : the international multidisciplinary research and review journal}, publisher = {Elsevier}, address = {Oxford}, organization = {Olorgesailie Drilling Project Sci}, issn = {0277-3791}, doi = {10.1016/j.quascirev.2019.05.009}, pages = {213 -- 231}, year = {2019}, abstract = {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.}, language = {en} } @article{BaroniDrastigLichtenfeldetal.2019, author = {Baroni, Gabriele and Drastig, Katrin and Lichtenfeld, Anna-Ulrike and Jost, Leonie and Claas, Peter}, title = {Assessment of irrigation scheduling systems in Germany}, series = {Irrigation and drainage}, volume = {68}, journal = {Irrigation and drainage}, number = {3}, publisher = {Wiley}, address = {Hoboken}, issn = {1531-0353}, doi = {10.1002/ird.2337}, pages = {520 -- 530}, year = {2019}, abstract = {In Germany, the irrigation sector accounts for only 1\% of water use. In recent years, however, this sector has attracted more attention due to the occurrence of severe drought periods. Irrigation scheduling systems could support adaptation strategies but little is known about current providers, performance and users. In this study we aimed to depict the current situation of the existence and functioning of irrigation scheduling systems available in Germany. Six methods were identified and assessed based on direct interviews with end-users and a comparative analysis. The results showed a positive feedback from the users. However, the recommendations were rarely implemented, while only the seasonal irrigation requirement was considered to support actual water abstraction. These results were corroborated by the comparative analysis. Five of the six irrigation scheduling systems estimated the seasonal irrigation amount consistently, while wider differences were found by looking at the irrigation season and at the number of irrigations. Overall, it is found that irrigation support systems are valuable tools for supporting adaptation strategies to fast changes in agro-environmental conditions. However, specific assessments based on real measurements should be considered in order to improve the performance of the systems and provide more consistent support to end-users. (c) 2019 John Wiley \& Sons, Ltd.}, language = {en} } @article{SchefflerImmenhauserPourteauetal.2019, author = {Scheffler, Franziska and Immenhauser, Adrian and Pourteau, Amaury and Natalicchio, Marcello and Candan, Osman and Oberh{\"a}nsli, Roland}, title = {A lost Tethyan evaporitic basin}, series = {Sedimentology : the journal of the International Association of Sedimentologists}, volume = {66}, journal = {Sedimentology : the journal of the International Association of Sedimentologists}, number = {7}, publisher = {Wiley}, address = {Hoboken}, issn = {0037-0746}, doi = {10.1111/sed.12606}, pages = {2627 -- 2660}, year = {2019}, abstract = {Ancient evaporite deposits are geological archives of depositional environments characterized by a long-term negative precipitation balance and bear evidence for global ocean element mass balance calculations. Here, Cretaceous selenite pseudomorphs from western Anatolia ('Rosetta Marble') — characterized by their exceptional morphological preservation — and their 'marine' geochemical signatures are described and interpreted in a process-oriented context. These rocks recorded Late Cretaceous high-pressure/low-temperature, subduction-related metamorphism with peak conditions of 1·0 to 1·2 GPa and 300 to 400°C. Metre-scale, rock-forming radiating rods, now present as fibrous calcite marble, clearly point to selenitic gypsum as the precursor mineral. Stratigraphic successions are recorded along a reconstructed proximal to distal transect. The cyclical alternation of selenite beds and radiolarian ribbon-bedded cherts in the distal portions are interpreted as a two type of seawater system. During arid intervals, shallow marine brines cascaded downward into basinal settings and induced precipitation. During more humid times, upwelling-induced radiolarian blooms caused the deposition of radiolarite facies. Interestingly, there is no comparable depositional setting known from the Cenozoic world. Meta-selenite geochemical data (δ13C, δ18O and 87Sr/86Sr) plot within the range of reconstructed middle Cretaceous seawater signatures. Possible sources for the 13C-enriched (mean 2·2 per mille) values include methanogenesis, gas hydrates and cold seep fluid exhalation. Spatially resolved component-specific analysis of a rock slab displays isotopic variances between meta-selenite crystals (mean δ13C 2·2 per mille) and host matrix (mean δ13C 1·3 per mille). The Cretaceous evaporite-pseudomorphs of Anatolia represent a basin wide event coeval with the Aptian evaporites of the Proto-Atlantic and the pseudomorphs share many attributes, including lateral distribution of 600 km and stratigraphic thickness of 1·5 to 2·0 km, with the evaporites formed during the younger Messinian salinity crisis. The Rosetta Marble of Anatolia may represent the best-preserved selenite pseudomorphs worldwide and have a clear potential to act as a template for the study of meta-selenite in deep time.}, language = {en} } @article{MartinPuertasLauterbachAllenetal.2019, author = {Martin-Puertas, Celia and Lauterbach, Stefan and Allen, Judy R. M. and Perez, Marta and Blockley, Simon and Wulf, Sabine and Huntley, Brian and Brauer, Achim}, title = {Initial Mediterranean response to major climate reorganization during the last interglacial-glacial transition}, series = {Quaternary science reviews : the international multidisciplinary research and review journal}, volume = {215}, journal = {Quaternary science reviews : the international multidisciplinary research and review journal}, publisher = {Elsevier}, address = {Oxford}, issn = {0277-3791}, doi = {10.1016/j.quascirev.2019.05.019}, pages = {232 -- 241}, year = {2019}, abstract = {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.}, language = {en} } @article{RoderHudsonTaroili2019, author = {Roder, Giulia and Hudson, Paul and Taroili, Paolo}, title = {Flood risk perceptions and the willingness to pay for flood insurance in the Veneto region of Italy}, series = {International Journal of Disaster Risk Reduction}, volume = {37}, journal = {International Journal of Disaster Risk Reduction}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2212-4209}, doi = {10.1016/j.ijdrr.2019.101172}, pages = {10}, year = {2019}, abstract = {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.}, language = {en} } @article{SobolevBrown2019, author = {Sobolev, Stephan Vladimir and Brown, Michael}, title = {Surface erosion events controlled the evolution of plate tectonics on Earth}, series = {Nature : international weekly journal of science}, volume = {570}, journal = {Nature : international weekly journal of science}, number = {7759}, publisher = {Nature Publ. Group}, address = {London}, issn = {0028-0836}, doi = {10.1038/s41586-019-1258-4}, pages = {52 -- +}, year = {2019}, abstract = {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.}, language = {en} } @article{CordonnierBovyBraun2019, author = {Cordonnier, Guillaume and Bovy, Benoit and Braun, Jean}, title = {A versatile, linear complexity algorithm for flow routing in topographies with depressions}, series = {Earth surface dynamics}, volume = {7}, journal = {Earth surface dynamics}, number = {2}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {2196-6311}, doi = {10.5194/esurf-7-549-2019}, pages = {549 -- 562}, year = {2019}, abstract = {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.}, language = {en} }