TY  - JOUR
A1  - Nwosu, Ebuka Canisius
A1  - Brauer, Achim
A1  - Kaiser, Jérôme
A1  - Horn, Fabian
A1  - Wagner, Dirk
A1  - Liebner, Susanne
T1  - Evaluating sedimentary DNA for tracing changes in cyanobacteria dynamics from sediments spanning the last 350 years of Lake Tiefer See, NE Germany
JF  - Journal of paleolimnology
N2  - Since the beginning of the Anthropocene, lacustrine biodiversity has been influenced by climate change and human activities. These factors advance the spread of harmful cyanobacteria in lakes around the world, which affects water quality and impairs the aquatic food chain. In this study, we assessed changes in cyanobacterial community dynamics via sedimentary DNA (sedaDNA) from well-dated lake sediments of Lake Tiefer See, which is part of the Klocksin Lake Chain spanning the last 350 years. Our diversity and community analysis revealed that cyanobacterial communities form clusters according to the presence or absence of varves. Based on distance-based redundancy and variation partitioning analyses (dbRDA and VPA) we identified that intensified lake circulation inferred from vegetation openness reconstructions, delta C-13 data (a proxy for varve preservation) and total nitrogen content were abiotic factors that significantly explained the variation in the reconstructed cyanobacterial community from Lake Tiefer See sediments. Operational taxonomic units (OTUs) assigned to Microcystis sp. and Aphanizomenon sp. were identified as potential eutrophication-driven taxa of growing importance since circa common era (ca. CE) 1920 till present. This result is corroborated by a cyanobacteria lipid biomarker analysis. Furthermore, we suggest that stronger lake circulation as indicated by non-varved sediments favoured the deposition of the non-photosynthetic cyanobacteria sister clade Sericytochromatia, whereas lake bottom anoxia as indicated by subrecent- and recent varves favoured the Melainabacteria in sediments. Our findings highlight the potential of high-resolution amplicon sequencing in investigating the dynamics of past cyanobacterial communities in lake sediments and show that lake circulation, anoxic conditions, and human-induced eutrophication are main factors explaining variations in the cyanobacteria community in Lake Tiefer See during the last 350 years.
KW  - Late Holocene
KW  - Methylheptadecanes
KW  - Varves
KW  - Anthropocene
KW  - Sericytochromatia
KW  - Melainabacteria
Y1  - 2021
U6  - https://doi.org/10.1007/s10933-021-00206-9
SN  - 0921-2728
SN  - 1573-0417
VL  - 66
IS  - 3
SP  - 279
EP  - 296
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Zhu, Zhennan
A1  - Tian, Hong
A1  - Kempka, Thomas
A1  - Jiang, Guosheng
A1  - Dou, Bin
A1  - Mei, Gang
T1  - Mechanical behaviors of granite after thermal treatment under loading and unloading conditions
JF  - Natural resources research / sponsored by the International Association for Mathematical Geology
N2  - Understanding the mechanical behaviors of granite after thermal treatment under loading and unloading conditions is of utmost relevance to deep geothermal energy recovery. In the present study, a series of loading and unloading triaxial compression tests (20, 40 and 60 MPa) on granite specimens after exposure to different temperatures (20, 200, 300, 400, 500 and 600 degrees C) was carried out to quantify the combined effects of thermal treatment and loading/unloading stress conditions on granite strength and deformation. Changes in the microstructure of granite exposed to high temperatures were revealed by optical microscopy. The experimental results indicate that both, thermal treatment and loading/unloading stress conditions, degrade the mechanical behaviors and further decrease the carrying capacity of granite. The gradual degradation of the mechanical characteristics of granite after thermal treatment is mainly associated with the evolution of thermal micro-cracks based on optical microscopy observations. The unloading stress state induces the extension of tension cracks parallel to the axial direction, and thus, the mechanical properties are degraded. Temperatures above 400 degrees C have a more significant influence on the mechanical characteristics of granite than the unloading treatment, whereby 400 degrees C can be treated as a threshold temperature for the delineation of significant deterioration. This study is expected to support feasibility and risk assessments by means of providing data for analytical calculations and numerical simulations on granite exposed to high temperatures during geothermal energy extraction.
KW  - Granite
KW  - Thermal treatment
KW  - Unloading
KW  - Mechanical properties
KW  - Micro-structure
Y1  - 2021
U6  - https://doi.org/10.1007/s11053-021-09815-7
SN  - 1520-7439
SN  - 1573-8981
VL  - 30
IS  - 3
SP  - 2733
EP  - 2752
PB  - Springer Science + Business Media B.V.
CY  - New York, NY [u.a.]
ER  - 
TY  - JOUR
A1  - Jozi Najafabadi, Azam
A1  - Haberland, Christian
A1  - Ryberg, Trond
A1  - Verwater, Vincent F.
A1  - Breton, Eline le
A1  - Handy, Mark R.
A1  - Weber, Michael
T1  - Relocation of earthquakes in the southern and eastern Alps (Austria, Italy) recorded by the dense, temporary SWATH-D network using a Markov chain Monte Carlo inversion
JF  - Solid earth : SE ; an interaktive open access journal of the European Geosciences Union
N2  - In this study, we analyzed a large seismological dataset from temporary and permanent networks in the southern and eastern Alps to establish high-precision hypocenters and 1-D V-P and V-P/V-S models. The waveform data of a subset of local earthquakes with magnitudes in the range of 1-4.2 M-L were recorded by the dense, temporary SWATH-D network and selected stations of the AlpArray network between September 2017 and the end of 2018. The first arrival times of P and S waves of earthquakes are determined by a semi-automatic procedure. We applied a Markov chain Monte Carlo inversion method to simultaneously calculate robust hypocenters, a 1-D velocity model, and station corrections without prior assumptions, such as initial velocity models or earthquake locations. A further advantage of this method is the derivation of the model parameter uncertainties and noise levels of the data. The precision estimates of the localization procedure is checked by inverting a synthetic travel time dataset from a complex 3-D velocity model and by using the real stations and earthquakes geometry. The location accuracy is further investigated by a quarry blast test. The average uncertainties of the locations of the earthquakes are below 500m in their epicenter and similar to 1.7 km in depth. The earthquake distribution reveals seismicity in the upper crust (0-20 km), which is characterized by pronounced clusters along the Alpine frontal thrust, e.g., the Friuli-Venetia (FV) region, the Giudicarie-Lessini (GL) and Schio-Vicenza domains, the Austroalpine nappes, and the Inntal area. Some seismicity also occurs along the Periadriatic Fault. The general pattern of seismicity reflects head-on convergence of the Adriatic indenter with the Alpine orogenic crust. The seismicity in the FV and GL regions is deeper than the modeled frontal thrusts, which we interpret as indication for southward propagation of the southern Alpine deformation front (blind thrusts).
Y1  - 2021
U6  - https://doi.org/10.5194/se-12-1087-2021
SN  - 1869-9529
VL  - 12
IS  - 5
SP  - 1087
EP  - 1109
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Genderjahn, Steffi
A1  - Lewin, Simon
A1  - Horn, Fabian
A1  - Schleicher, Anja M.
A1  - Mangelsdorf, Kai
A1  - Wagner, Dirk
T1  - Living lithic and sublithic bacterial communities in Namibian drylands
JF  - Microorganisms : open access journal
N2  - Dryland xeric conditions exert a deterministic effect on microbial communities, forcing life into refuge niches. Deposited rocks can form a lithic niche for microorganisms in desert regions. Mineral weathering is a key process in soil formation and the importance of microbial-driven mineral weathering for nutrient extraction is increasingly accepted. Advances in geobiology provide insight into the interactions between microorganisms and minerals that play an important role in weathering processes. In this study, we present the examination of the microbial diversity in dryland rocks from the Tsauchab River banks in Namibia. We paired culture-independent 16S rRNA gene amplicon sequencing with culture-dependent (isolation of bacteria) techniques to assess the community structure and diversity patterns. Bacteria isolated from dryland rocks are typical of xeric environments and are described as being involved in rock weathering processes. For the first time, we extracted extra- and intracellular DNA from rocks to enhance our understanding of potentially rock-weathering microorganisms. We compared the microbial community structure in different rock types (limestone, quartz-rich sandstone and quartz-rich shale) with adjacent soils below the rocks. Our results indicate differences in the living lithic and sublithic microbial communities.
KW  - lithobiont
KW  - intracellular DNA
KW  - extracellular DNA
KW  - weathering
KW  - dryland
KW  - rock
Y1  - 2021
U6  - https://doi.org/10.3390/microorganisms9020235
SN  - 2076-2607
VL  - 9
IS  - 2
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Schultze, Dina
A1  - Wirth, Richard
A1  - Wunder, Bernd
A1  - Loges, Anselm
A1  - Wilke, Max
A1  - Franz, Gerhard
T1  - Corundum-quartz metastability
BT  - the influence of a nanometer-sized phase on mineral equilibria in the system Al2O3-SiO2-H2O
JF  - Contributions to mineralogy and petrology
N2  - The metastable paragenesis of corundum and quartz is rare in nature but common in laboratory experiments where according to thermodynamic predictions aluminum-silicate polymorphs should form. We demonstrate here that the existence of a hydrous, silicon-bearing, nanometer-thick layer (called "HSNL") on the corundum surface can explain this metastability in experimental studies without invoking unspecific kinetic inhibition. We investigated experimentally formed corundum reaction products synthesized during hydrothermal and piston-cylinder experiments at 500-800 degrees C and 0.25-1.8 GPa and found that this HSNL formed inside and on the corundum crystals, thereby controlling the growth behavior of its host. The HSNL represents a substitution of Al with Si and H along the basal plane of corundum. Along the interface of corundum and quartz, the HSNL effectively isolates the bulk phases corundum and quartz from each other, thus apparently preventing their reaction to the stable aluminum silicate. High temperatures and prolonged experimental duration lead to recrystallization of corundum including the HSNL and to the formation of quartz + fluid inclusions inside the host crystal. This process reduces the phase boundary area between the bulk phases, thereby providing further opportunity to expand their coexistence. In addition to its small size, its transient nature makes it difficult to detect the HSNL in experiments and even more so in natural samples. Our findings emphasize the potential impact of nanometer-sized phases on geochemical reaction pathways and kinetics under metamorphic conditions in one of the most important chemical systems of the Earth's crust.
KW  - Experimental
KW  - Metastability
KW  - Corundum
KW  - Quartz
KW  - Nanolayers
KW  - Aluminium– silicates
Y1  - 2021
U6  - https://doi.org/10.1007/s00410-021-01786-5
SN  - 0010-7999
SN  - 1432-0967
VL  - 176
IS  - 4
PB  - Springer
CY  - Berlin ; Heidelberg
ER  - 
TY  - JOUR
A1  - Codeço, Marta S.
A1  - Weis, Philipp
A1  - Trumbull, Robert B.
A1  - Van Hinsberg, Vincent
A1  - Pinto, Filipe
A1  - Lecumberri-Sanchez, Pilar
A1  - Schleicher, Anja Maria
T1  - The imprint of hydrothermal fluids on trace-element contents in white mica and tourmaline from the Panasqueira W–Sn–Cu deposit, Portugal
JF  - Mineralium Deposita
N2  - White mica and tourmaline are the dominant hydrothermal alteration minerals at the world-class Panasqueira W-Sn-Cu deposit in Portugal. Thus, understanding the controls on their chemical composition helps to constrain ore formation processes at this deposit and determine their usefulness as pathfinder minerals for mineralization in general. We combine whole-rock geochemistry of altered and unaltered metasedimentary host rocks with in situ LA-ICP-MS measurements of tourmaline and white mica from the alteration halo. Principal component analysis (PCA) is used to better identify geochemical patterns and trends of hydrothermal alteration in the datasets. The hydrothermally altered metasediments are enriched in As, Sn, Cs, Li, W, F, Cu, Rb, Zn, Tl, and Pb relative to unaltered samples. In situ mineral analyses show that most of these elements preferentially partition into white mica over tourmaline (Li, Rb, Cs, Tl, W, and Sn), whereas Zn is enriched in tourmaline. White mica has distinct compositions in different settings within the deposit (greisen, vein selvages, wall rock alteration zone, late fault zone), indicating a compositional evolution with time. In contrast, tourmaline from different settings overlaps in composition, which is ascribed to a stronger dependence on host rock composition and also to the effects of chemical zoning and microinclusions affecting the LA-ICP-MS analyses. Hence, in this deposit, white mica is the better recorder of the fluid composition. The calculated trace-element contents of the Panasqueira mineralizing fluid based on the mica data and estimates of mica-fluid partition coefficients are in good agreement with previous fluid-inclusion analyses. A compilation of mica and tourmaline trace-element compositions from Panasqueira and other W-Sn deposits shows that white mica has good potential as a pathfinder mineral, with characteristically high Li, Cs, Rb, Sn, and W contents. The trace-element contents of hydrothermal tourmaline are more variable. Nevertheless, the compiled data suggest that high Sn and Li contents are distinctive for tourmaline from W-Sn deposits.
KW  - alteration geochemistry
KW  - tourmaline
KW  - white mica
KW  - Panasqueira
KW  - Tungsten–tin deposits
KW  - magmatic-hydrothermal systems
KW  - trace elements
Y1  - 2020
U6  - https://doi.org/10.1007/s00126-020-00984-8
SN  - 1432-1866
SN  - 0026-4598
VL  - 56
IS  - 3
SP  - 481
EP  - 508
PB  - Springer
CY  - Berlin; Heidelberg
ER  - 
TY  - JOUR
A1  - Santamans, Carla Daniela
A1  - Cordoba, Francisco E.
A1  - Franco, María G.
A1  - Vignoni, Paula
A1  - Lupo, Liliana C.
T1  - Hydro-climatological variability in Lagunas de Vilama System, Argentinean Altiplano-Puna Plateau, Southern Tropical Andes (22 degrees S) and its response to large-scale climate forcings
JF  - The science of the total environment : an international journal for scientific research into the environment and its relationship with man
N2  - The Altiplano-Puna Plateau holds several shallow lakes, which are very sensitive to climate changes. This work is focused on a high-altitude lake system called Lagunas de Vilama (LVS), located in a complex climatic transition area with scarcity of continuous and homogeneous instrumental records. The objective of this study is to determine the regional spatial-temporal variability of precipitation and evaluate the seasonal and interannual lake responses. We use a lake-surfaces record derived from Landsat images to investigate links with regional precipitations and different climatic forcings. The results reveal that austral summer and autumn precipitations control the variability of the annual lake-surfaces. Also, we found intra-annual and interannual lags in the lake responses to precipitations, and identified several wet and dry stages. Our results show negative trends in precipitations and lake-surfaces, whose were strengthened by a shift to a warm phase of the Atlantic Multidecadal Oscillation in the 1990s. The El Nino Southern Oscillation, Pacific Decadal Oscillation, and Southern Annular Mode also exert a strong influence in the region. This study demonstrates that the variability of LVS lakes is strongly related to the South American Monsoon System dynamics and large-scale climate fordngs from the Pacific and Atlantic Oceans. This work provides novel indices which demonstrated to be good indicators of regional hydroclimatological variability for this region of South America.
KW  - Lake-surfaces variability
KW  - Precipitation variability
KW  - Hydro-meteorological indices
KW  - Regional forcings
KW  - South American Monsoon
KW  - System
KW  - Andean plateau
Y1  - 2021
U6  - https://doi.org/10.1016/j.scitotenv.2020.144926
SN  - 0048-9697
SN  - 1879-1026
VL  - 767
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Pilz, Marco
A1  - Isken, Marius Paul
A1  - Fleming, Kevin
A1  - Orunbaev, Sagynbek
A1  - Moldobekov, Bolot
T1  - Long- and short-term monitoring of a dam in response to seasonal changes and ground motion loading
BT  - the test case of the Kurpsai Dam, Western Kyrgyz Republic
JF  - Pure and applied geophysics : PAGEOPH ; continuation of Geofisica pura e applicata
N2  - An experimental multi-parameter structural monitoring system has been installed on the Kurpsai dam, western Kyrgyz Republic. This system consists of equipment for seismic and strain measurements for making longer- (days, weeks, months) and shorter- (minutes, hours) term observations, dealing with, for example seasonal (longer) effects or the response of the dam to ground motion from noise or seismic events. Fibre-optic strain sensors allow the seasonal and daily opening and closing of the spaces between the dam's segments to be tracked. For the seismic data, both amplitude (in terms of using differences in amplitudes in the Fourier spectra for mapping the modes of vibration of the dam) and their time-frequency distribution for a set of small to moderate seismic events are investigated and the corresponding phase variabilities (in terms of lagged coherency) are evaluated. Even for moderate levels of seismic-induced ground motion, some influence on the structural response can be detected, which then sees the dam quickly return to its original state. A seasonal component was identified in the strain measurements, while levels of noise arising from the operation of the dam's generators and associated water flow have been provisionally identified.
KW  - Structural health monitoring
KW  - Dam engineering
KW  - Operational and environmental effects
KW  - Strong-motion
KW  - Strain
KW  - Elastic response
KW  - Kurpsai dam
Y1  - 2021
U6  - https://doi.org/10.1007/s00024-021-02861-5
SN  - 0033-4553
SN  - 1420-9136
VL  - 178
IS  - 10
SP  - 4001
EP  - 4020
PB  - Birkhäuser
CY  - Basel
ER  - 
TY  - JOUR
A1  - Vasyura-Bathke, Hannes
A1  - Dettmer, Jan
A1  - Dutta, Rishabh
A1  - Mai, Paul Martin
A1  - Jónsson, Sigurjón
T1  - Accounting for theory errors with empirical Bayesian noise models in nonlinear centroid moment tensor estimation
JF  - Geophysical journal international / the Royal Astronomical Society, the Deutsche Geophysikalische Gesellschaft and the European Geophysical Society
N2  - Centroid moment tensor (CMT) parameters can be estimated from seismic waveforms. Since these data indirectly observe the deformation process, CMTs are inferred as solutions to inverse problems which are generally underdetermined and require significant assumptions, including assumptions about data noise. Broadly speaking, we consider noise to include both theory and measurement errors, where theory errors are due to assumptions in the inverse problem and measurement errors are caused by the measurement process. While data errors are routinely included in parameter estimation for full CMTs, less attention has been paid to theory errors related to velocity-model uncertainties and how these affect the resulting moment-tensor (MT) uncertainties. Therefore, rigorous uncertainty quantification for CMTs may require theory-error estimation which becomes a problem of specifying noise models. Various noise models have been proposed, and these rely on several assumptions. All approaches quantify theory errors by estimating the covariance matrix of data residuals. However, this estimation can be based on explicit modelling, empirical estimation and/or ignore or include covariances. We quantitatively compare several approaches by presenting parameter and uncertainty estimates in nonlinear full CMT estimation for several simulated data sets and regional field data of the M-1 4.4, 2015 June 13 Fox Creek, Canada, event. While our main focus is at regional distances, the tested approaches are general and implemented for arbitrary source model choice. These include known or unknown centroid locations, full MTs, deviatoric MTs and double-couple MTs. We demonstrate that velocity-model uncertainties can profoundly affect parameter estimation and that their inclusion leads to more realistic parameter uncertainty quantification. However, not all approaches perform equally well. Including theory errors by estimating non-stationary (non-Toeplitz) error covariance matrices via iterative schemes during Monte Carlo sampling performs best and is computationally most efficient. In general, including velocity-model uncertainties is most important in cases where velocity structure is poorly known.
KW  - Inverse theory
KW  - Probability distributions
KW  - Waveform inversion
KW  - Earthquake source observations
KW  - Seismic noise
Y1  - 2021
U6  - https://doi.org/10.1093/gji/ggab034
SN  - 0956-540X
SN  - 1365-246X
VL  - 225
IS  - 2
SP  - 1412
EP  - 1431
PB  - Oxford University Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Monhonval, Arthur
A1  - Strauss, Jens
A1  - Mauclet, Elisabeth
A1  - Hirst, Catherine
A1  - Bemelmans, Nathan
A1  - Grosse, Guido
A1  - Schirrmeister, Lutz
A1  - Fuchs, Matthias
A1  - Opfergelt, Sophie
T1  - Iron redistribution upon thermokarst processes in the Yedoma domain
JF  - Frontiers in Earth Science
N2  - Ice-rich permafrost has been subject to abrupt thaw and thermokarst formation in the past and is vulnerable to current global warming. The ice-rich permafrost domain includes Yedoma sediments that have never thawed since deposition during the late Pleistocene and Alas sediments that were formed by previous thermokarst processes during the Lateglacial and Holocene warming. Permafrost thaw unlocks organic carbon (OC) and minerals from these deposits and exposes OC to mineralization. A portion of the OC can be associated with iron (Fe), a redox-sensitive element acting as a trap for OC. Post-depositional thaw processes may have induced changes in redox conditions in these deposits and thereby affected Fe distribution and interactions between OC and Fe, with knock-on effects on the role that Fe plays in mediating present day OC mineralization. To test this hypothesis, we measured Fe concentrations and proportion of Fe oxides and Fe complexed with OC in unthawed Yedoma and previously thawed Alas deposits. Total Fe concentrations were determined on 1,292 sediment samples from the Yedoma domain using portable X-ray fluorescence; these concentrations were corrected for trueness using a calibration based on a subset of 144 samples measured by inductively coupled plasma optical emission spectrometry after alkaline fusion (R (2) = 0.95). The total Fe concentration is stable with depth in Yedoma deposits, but we observe a depletion or accumulation of total Fe in Alas deposits, which experienced previous thaw and/or flooding events. Selective Fe extractions targeting reactive forms of Fe on unthawed and previously thawed deposits highlight that about 25% of the total Fe is present as reactive species, either as crystalline or amorphous oxides, or complexed with OC, with no significant difference in proportions of reactive Fe between Yedoma and Alas deposits. These results suggest that redox driven processes during past thermokarst formation impact the present-day distribution of total Fe, and thereby the total amount of reactive Fe in Alas versus Yedoma deposits. This study highlights that ongoing thermokarst lake formation and drainage dynamics in the Arctic influences reactive Fe distribution and thereby interactions between Fe and OC, OC mineralization rates, and greenhouse gas emissions.
KW  - permafrost
KW  - thaw
KW  - redox processes
KW  - carbon stabilization
KW  - arctic
KW  - subarctic
Y1  - 2021
U6  - https://doi.org/10.3389/feart.2021.703339
SN  - 2296-6463
VL  - 9
PB  - Frontiers Media
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Degen, Denise
A1  - Spooner, Cameron
A1  - Scheck-Wenderoth, Magdalena
A1  - Cacace, Mauro
T1  - How biased are our models?
BT  - a case study of the alpine region
JF  - Geoscientific model development : an interactive open access journal of the European Geosciences Union
N2  - Geophysical process simulations play a crucial role in the understanding of the subsurface. This understanding is required to provide, for instance, clean energy sources such as geothermal energy. However, the calibration and validation of the physical models heavily rely on state measurements such as temperature. In this work, we demonstrate that focusing analyses purely on measurements introduces a high bias. This is illustrated through global sensitivity studies. The extensive exploration of the parameter space becomes feasible through the construction of suitable surrogate models via the reduced basis method, where the bias is found to result from very unequal data distribution. We propose schemes to compensate for parts of this bias. However, the bias cannot be entirely compensated. Therefore, we demonstrate the consequences of this bias with the example of a model calibration.
Y1  - 2021
U6  - https://doi.org/10.5194/gmd-14-7133-2021
SN  - 1991-959X
SN  - 1991-9603
VL  - 14
IS  - 11
SP  - 7133
EP  - 7153
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Kulahci, Gullu Deniz
A1  - Cichy, Sarah Bettina
A1  - Temel, Abidin
A1  - Spallanzani, Roberta
T1  - Pre-eruptive PTX fluid-conditions of the Afyon Volcanic Complex (Western Anatolia, Turkey)
BT  - Studies of natural rocks and phase equilibria experiments
JF  - Lithos : an international journal of mineralogy, petrology, and geochemistry
N2  - This study is trying to understand the pre-eruptive magma storage and crystallization conditions of the Middle Miocene aged, silica-saturated trachytic rocks of the Afyon Volcanic Complex (AVC) in Western Anatolia, Turkey. Those rocks can be divided by their high K2O, K2O/Na2O ratio and Mg# into two groups, namely the intermediate-potassic (IPG) and the ultrapotassic (UPG). Here we are comparing calculated pressure (P) - temperature (T) conditions derived from geothermobarometric calculations of natural samples with results of high-pressure, high-temperature phase equilibria experiments. IPG samples are richer in silica (57-64 wt% SiO2), whereas UPG samples show intermediate SiO2 contents of 56-58 wt%. UPG are having high K2O contents ((>)9 wt %), K2O/Na2O ratios ((>)10 wt%) and Mg# values (75-77). IPG phenocrysts comprise plagioclase + biotite + amphibole + clinopyroxene +/- orthopyroxene +/- sanidine +/- phlogopite and oxides, while UPG mineralogical assemblage consists of amphibole + phlogopite + clinopyroxene + olivine + sanidine and oxides. IPG and UPG are enriched in Large-Ion Lithophile Elements (LILE), and both have negative anomalies in Nb, Sr, Zr and Ti elements. Additionally, IPG shows positive anomalies in Pb. Both IPG and UPG display enrichment in Light Rare Earth Elements (LREE), while IPG shows a more significant negative anomaly in Eu when compared to UPG. Plagioclase fractionation may play a role in magma generation. In IPG samples Ni and Cr values range between (3.3-18.8 ppm) and (2.6-27.8 ppm), respectively; whereas UPG samples have (119.1-120.7 ppm) Ni and (212.1-219.9 ppm) Cr. Dy/Yb ratios of IPG and UPG are higher than 2 and may indicate that garnet was present in the source. Geothermobarometric calculations for natural IPG clinopyroxene-melt pairs imply higher PT conditions (Dogan-Kulahci et al., 2015), while in this study high-pressure/high-temperature (HP/HT) phase equilibria experiments recreated the natural mineral assemblage at 2-4 kbar, 6-9 km and c. 900 degrees C. New plagioclase-melt calculations have confirmed lower mean magma storage temperatures, which are closer to the experimental results but still slightly elevated. Thus, trace element results of the natural rocks and experimental data may imply that a deep garnet-bearing magma source mixed with shallower magmas (IPG) was feeding the volcanic eruption.
KW  - Afyon volcanics
KW  - Geothermobarometry
KW  - Experimental petrology
KW  - High-pressure
KW  - High-temperature experiments
Y1  - 2021
U6  - https://doi.org/10.1016/j.lithos.2021.106297
SN  - 0024-4937
SN  - 1872-6143
VL  - 398
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Nwosu, Ebuka Canisius
A1  - Roeser, Patricia Angelika
A1  - Yang, Sizhong
A1  - Pinkerneil, Sylvia
A1  - Ganzert, Lars
A1  - Dittmann, Elke
A1  - Brauer, Achim
A1  - Wagner, Dirk
A1  - Liebner, Susanne
T1  - Species-level spatio-temporal dynamics of cyanobacteria in a hard-water temperate lake in the Southern Baltics
JF  - Frontiers in microbiology
N2  - Cyanobacteria are important primary producers in temperate freshwater ecosystems. However, studies on the seasonal and spatial distribution of cyanobacteria in deep lakes based on high-throughput DNA sequencing are still rare. In this study, we combined monthly water sampling and monitoring in 2019, amplicon sequence variants analysis (ASVs; a proxy for different species) and quantitative PCR targeting overall cyanobacteria abundance to describe the seasonal and spatial dynamics of cyanobacteria in the deep hard-water oligo-mesotrophic Lake Tiefer See, NE Germany. We observed significant seasonal variation in the cyanobacterial community composition (p < 0.05) in the epi- and metalimnion layers, but not in the hypolimnion. In winter-when the water column is mixed-picocyanobacteria (Synechococcus and Cyanobium) were dominant. With the onset of stratification in late spring, we observed potential niche specialization and coexistence among the cyanobacteria taxa driven mainly by light and nutrient dynamics. Specifically, ASVs assigned to picocyanobacteria and the genus Planktothrix were the main contributors to the formation of deep chlorophyll maxima along a light gradient. While Synechococcus and different Cyanobium ASVs were abundant in the epilimnion up to the base of the euphotic zone from spring to fall, Planktothrix mainly occurred in the metalimnetic layer below the euphotic zone where also overall cyanobacteria abundance was highest in summer. Our data revealed two potentially psychrotolerant (cold-adapted) Cyanobium species that appear to cope well under conditions of lower hypolimnetic water temperature and light as well as increasing sediment-released phosphate in the deeper waters in summer. The potential cold-adapted Cyanobium species were also dominant throughout the water column in fall and winter. Furthermore, Snowella and Microcystis-related ASVs were abundant in the water column during the onset of fall turnover. Altogether, these findings suggest previously unascertained and considerable spatiotemporal changes in the community of cyanobacteria on the species level especially within the genus Cyanobium in deep hard-water temperate lakes.
KW  - Cyanobium
KW  - picocyanobacteria diversity
KW  - amplicon sequencing
KW  - lake monitoring
KW  - ecological succession
KW  - lake stratification
KW  - psychrotolerant
Y1  - 2021
U6  - https://doi.org/10.3389/fmicb.2021.761259
SN  - 1664-302X
VL  - 12
PB  - Frontiers Media
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Ghani, Humaad
A1  - Sobel, Edward
A1  - Zeilinger, Gerold
A1  - Glodny, Johannes
A1  - Irum, Irum
A1  - Sajid, Muhammad
T1  - Spatio-temporal structural evolution of the Kohat fold and thrust belt of Pakistan
JF  - Journal of structural geology
N2  - The Kohat fold and thrust belt in Pakistan shows a significantly different structural style due to the structural evolution on the double décollement  compared to the rest of the Subhimalaya. In order to better understand the spatio-temporal structural evolution of the Kohat fold and thrust belt, we combine balanced cross sections with apatite (U?Th-Sm)/He (AHe) and apatite fission track (AFT) dating. The AHe and AFT ages appear to be totally reset, allowing us to date exhumation above structural ramps. The results suggest that deformation began on the frontal Surghar thrust at-15 Ma, predating or coeval with the development of the Main Boundary thrust at-12 Ma. Deformation propagated southward from the Main Boundary thrust on double de?collements between 10 Ma and 2 Ma, resulting in a disharmonic structural style inside the Kohat fold and thrust belt. Thermal modeling of the thermochronologic data suggest that samples inside Kohat fold and thrust belt experienced cooling due to formation of the duplexes; this deformation facilitated tectonic thickening of the wedge and erosion of the Miocene to Pliocene foreland strata. The spatial distribution of AHe and AFT ages in combination with the structural forward model suggest that, in the Kohat fold and thrust belt, the wedge deformed in-sequence as a supercritical wedge (-15-12 Ma), then readjusted by out-sequence deformation (-12-0 Ma) within the Kohat fold and thrust belt into a sub-critical wedge.
KW  - Balanced cross section
KW  - Fold and thrust belt
KW  - Duplex
KW  - Exhumation
KW  - Décollement
Y1  - 2021
U6  - https://doi.org/10.1016/j.jsg.2021.104310
SN  - 0191-8141
VL  - 145
PB  - Elsevier
CY  - Amsterdam [u.a.]
ER  - 
TY  - JOUR
A1  - Büyükakpınar, Pınar
A1  - Aktar, Mustafa
A1  - Petersen, Gesa Maria
A1  - Köseoğlu, Ayşegül
T1  - Orientations of broadband stations of the KOERI seismic network (Turkey) from two independent methods
BT  - P- and Rayleigh-wave polarization
JF  - Seismological research letters / Seismological Society of America
N2  - The correct orientation of seismic sensors is critical for studies such as full moment tensor inversion, receiver function analysis, and shear-wave splitting. Therefore, the orientation of horizontal components needs to be checked and verified systematically. This study relies on two different waveform-based approaches, to assess the sensor orientations of the broadband network of the Kandilli Observatory and Earthquake Research Institute (KOERI). The network is an important backbone for seismological research in the Eastern Mediterranean Region and provides a comprehensive seismic data set for the North Anatolian fault. In recent years, this region became a worldwide field laboratory for continental transform faults. A systematic survey of the sensor orientations of the entire network, as presented here, facilitates related seismic studies. We apply two independent orientation tests, based on the polarization of P waves and Rayleigh waves to 123 broadband seismic stations, covering a period of 15 yr (2004-2018). For 114 stations, we obtain stable results with both methods. Approximately, 80% of the results agree with each other within 10 degrees. Both methods indicate that about 40% of the stations are misoriented by more than 10 degrees. Among these, 20 stations are misoriented by more than 20 degrees. We observe temporal changes of sensor orientation that coincide with maintenance work or instrument replacement. We provide time-dependent sensor misorientation correction values for the KOERI network in the supplemental material.
Y1  - 2021
U6  - https://doi.org/10.1785/0220200362
SN  - 0895-0695
SN  - 1938-2057
VL  - 92
IS  - 3
SP  - 1512
EP  - 1521
PB  - Seismological Society of America
CY  - Boulder, Colo.
ER  - 
TY  - JOUR
A1  - Kaiser, Soraya
A1  - Grosse, Guido
A1  - Boike, Julia
A1  - Langer, Moritz
T1  - Monitoring the transformation of Arctic landscapes
BT  - automated shoreline change detection of lakes using very high resolution imagery
JF  - Remote sensing / Molecular Diversity Preservation International (MDPI)
N2  - Water bodies are a highly abundant feature of Arctic permafrost ecosystems and strongly influence their hydrology, ecology and biogeochemical cycling. While very high resolution satellite images enable detailed mapping of these water bodies, the increasing availability and abundance of this imagery calls for fast, reliable and automatized monitoring. This technical work presents a largely automated and scalable workflow that removes image noise, detects water bodies, removes potential misclassifications from infrastructural features, derives lake shoreline geometries and retrieves their movement rate and direction on the basis of ortho-ready very high resolution satellite imagery from Arctic permafrost lowlands. We applied this workflow to typical Arctic lake areas on the Alaska North Slope and achieved a successful and fast detection of water bodies. We derived representative values for shoreline movement rates ranging from 0.40-0.56 m yr(-1) for lake sizes of 0.10 ha-23.04 ha. The approach also gives an insight into seasonal water level changes. Based on an extensive quantification of error sources, we discuss how the results of the automated workflow can be further enhanced by incorporating additional information on weather conditions and image metadata and by improving the input database. The workflow is suitable for the seasonal to annual monitoring of lake changes on a sub-meter scale in the study areas in northern Alaska and can readily be scaled for application across larger regions within certain accuracy limitations.
KW  - change detection
KW  - shoreline movement rate
KW  - shoreline movement direction
KW  - arctic water bodies
KW  - permafrost lowlands
KW  - automated monitoring
KW  - North
KW  - Slope
KW  - very high resolution imagery
Y1  - 2021
U6  - https://doi.org/10.3390/rs13142802
SN  - 2072-4292
VL  - 13
IS  - 14
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Falkowski, Sarah
A1  - Ehlers, Todd
A1  - Madella, Andrea
A1  - Glotzbach, Christoph
A1  - Georgieva, Viktoria
A1  - Strecker, Manfred
T1  - Glacial catchment erosion from detrital zircon (U-Th)/He thermochronology
BT  - Patagonian Andes
JF  - GR / AGU, American Geophysical Union: Earth surface
N2  - Alpine glacial erosion exerts a first-order control on mountain topography and sediment production, but its mechanisms are poorly understood. Observational data capable of testing glacial erosion and transport laws in glacial models are mostly lacking. New insights, however, can be gained from detrital tracer thermochronology. Detrital tracer thermochronology works on the premise that thermochronometer bedrock ages vary systematically with elevation, and that detrital downstream samples can be used to infer the source elevation sectors of sediments. We analyze six new detrital samples of different grain sizes (sand and pebbles) from glacial deposits and the modern river channel integrated with data from 18 previously analyzed bedrock samples from an elevation transect in the Leones Valley, Northern Patagonian Icefield, Chile (46.7 degrees S). We present 622 new detrital zircon (U-Th)/He (ZHe) single-grain analyses and 22 new bedrock ZHe analyses for two of the bedrock samples to determine age reproducibility. Results suggest that glacial erosion was focused at and below the Last Glacial Maximum and neoglacial equilibrium line altitudes, supporting previous modeling studies. Furthermore, grain age distributions from different grain sizes (sand, pebbles) might indicate differences in erosion mechanisms, including mass movements at steep glacial valley walls. Finally, our results highlight complications and opportunities in assessing glacigenic environments, such as dynamics of sediment production, transport, transient storage, and final deposition, that arise from settings with large glacio-fluvial catchments.
KW  - ZHe tracer thermochronology
KW  - glacial erosion
KW  - sediment production
KW  - grain
KW  - size fractions
KW  - Leones Glacier
KW  - Northern Patagonian Icefield
Y1  - 2021
U6  - https://doi.org/10.1029/2021JF006141
SN  - 2169-9003
SN  - 2169-9011
VL  - 126
IS  - 10
PB  - Wiley
CY  - Hoboken, NJ
ER  - 
TY  - JOUR
A1  - Neuharth, Derek
A1  - Brune, Sascha
A1  - Glerum, Anne
A1  - Morley, Chris K.
A1  - Yuan, Xiaoping
A1  - Braun, Jean
T1  - Flexural strike-slip basins
JF  - Geology : a venture in earth science reporting / the Geological Society of America
N2  - Strike-slip faults are classically associated with pull-apart basins where continental crust is thinned between two laterally offset fault segments. We propose a subsidence mechanism to explain the formation of a new type of basin where no substantial segment offset or synstrike-slip thinning is observed. Such "flexural strike-slip basins" form due to a sediment load creating accommodation space by bending the lithosphere. We use a two-way coupling between the geodynamic code ASPECT and surface-processes code FastScape to show that flexural strike-slip basins emerge if sediment is deposited on thin lithosphere close to a strike slip fault. These conditions were met at the Andaman Basin Central fault (Andaman Sea, Indian Ocean), where seismic reflection data provide evidence of a laterally extensive flexural basin with a depocenter located parallel to the strike-slip fault trace.
Y1  - 2021
U6  - https://doi.org/10.1130/G49351.1
SN  - 0091-7613
SN  - 1943-2682
VL  - 50
IS  - 3
SP  - 361
EP  - 365
PB  - American Institute of Physics
CY  - Boulder
ER  - 
TY  - JOUR
A1  - Eibl, Eva P. S.
A1  - Müller, Daniel
A1  - Walter, Thomas R.
A1  - Allahbakhshi, Masoud
A1  - Jousset, Philippe
A1  - Hersir, Gylfi Páll
A1  - Dahm, Torsten
T1  - Eruptive cycle and bubble trap of Strokkur Geyser, Iceland
JF  - Journal of geophysical research : JGR. B: Solid earth
N2  - The eruption frequency of geysers can be studied easily on the surface. However, details of the internal structure including possible water and gas filled chambers feeding eruptions and the driving mechanisms often remain elusive. We used a multidisciplinary network of seismometers, video cameras, water pressure sensors and one tiltmeter to study the eruptive cycle, internal structure, and mechanisms driving the eruptive cycle of Strokkur geyser in June 2018. An eruptive cycle at Strokkur always consists of four phases: (1) Eruption, (2) post-eruptive conduit refilling, (3) gas filling of the bubble trap, and (4) regular bubble collapse at shallow depth in the conduit. For a typical single eruption 19 +/- 4 bubble collapses occur in Phase 3 and 8 +/- 2 collapses in Phase 4 at a mean spacing of 1.52 +/- 0.29 and 24.5 +/- 5.9 s, respectively. These collapses release latent heat to the fluid in the bubble trap (Phase 3) and later to the fluid in the conduit (Phase 4). The latter eventually reaches thermodynamic conditions for an eruption. Single to sextuple eruptions have similar spacings between bubble collapses and are likely fed from the same bubble trap at 23.7 +/- 4.4 m depth, 13-23 m west of the conduit. However, the duration of the eruption and recharging phase linearly increases likely due to a larger water, gas and heat loss from the system. Our tremor data provides documented evidence for a bubble trap beneath a pool geyser.
KW  - bubble trap
KW  - eruptive cycle
KW  - geyser
KW  - hydrothermal systems
KW  - source
KW  - location
KW  - tremor
Y1  - 2021
U6  - https://doi.org/10.1029/2020JB020769
SN  - 2169-9313
SN  - 2169-9356
VL  - 126
IS  - 4
PB  - Wiley
CY  - Hoboken, NJ
ER  - 
TY  - JOUR
A1  - Klemme, Stephan
A1  - Feldhaus, Michael
A1  - Potapkin, Vasily
A1  - Wilke, Max
A1  - Borchert, Manuela
A1  - Louvel, Marion
A1  - Loges, Anselm
A1  - Rohrbach, Arno
A1  - Weitkamp, Petra
A1  - Welter, Edmund
A1  - Kokh, Maria A.
A1  - Schmidt, Christian
A1  - Testemale, Denis
T1  - A hydrothermal apparatus for x-ray absorption spectroscopy of hydrothermal fluids at DESY
JF  - Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques
N2  - We present a new autoclave that enables in situ characterization of hydrothermal fluids at high pressures and high temperatures at synchrotron x-ray radiation sources. The autoclave has been specifically designed to enable x-ray absorption spectroscopy in fluids with applications to mineral solubility and element speciation analysis in hydrothermal fluids in complex compositions. However, other applications, such as Raman spectroscopy, in high-pressure fluids are also possible with the autoclave. First experiments were run at pressures between 100 and 600 bars and at temperatures between 25 degrees C and 550 degrees C, and preliminary results on scheelite dissolution in fluids of different compositions show that the autoclave is well suited to study the behavior of ore-forming metals at P-T conditions relevant to the Earth's crust.
Y1  - 2021
U6  - https://doi.org/10.1063/5.0044767
SN  - 0034-6748
SN  - 1089-7623
VL  - 92
IS  - 6
PB  - AIP Publishing
CY  - Melville
ER  - 
TY  - JOUR
A1  - Obiri-Nyarko, Franklin
A1  - Duah, Anthony A.
A1  - Karikari, Anthony Y.
A1  - Agyekum, William A.
A1  - Manu, Evans
A1  - Tagoe, Ralph
T1  - Assessment of heavy metal contamination in soils at the Kpone landfill site, Ghana
BT  - implication for ecological and health risk assessment
JF  - Chemosphere : chemistry, biology and toxicology as related to environmental problems
N2  - Concentrations of lead (Pb), zinc (Zn), copper (Cu), mercury (Hg), and arsenic (As) in soils at the Kpone landfill site (Ghana) were determined using Atomic Absorption Spectrophotometry (AAS). Further analyses allowed establishing the degree of heavy metals (HMs) pollution, suitability of the soils for agriculture, sources of the HMs and their ecological and health risks. The site was divided into five zones, A, B, C, D, and E, and in all, seventeen (17) soil samples were collected. Average concentrations of Cu fell within the allowable range for agricultural soils in all the zones while average concentrations of Pb, Zn, Hg, and As exceeded the range in some or all the zones. Concentrations of the HMs generally exceeded their respective background value, with all zones showing very high degree of HMs contamination. The pollution load index (PLI) was 16.48, signifying extreme HMs pollution of the entire site. Multivariate statistical analyses revealed that Cu, Zn, and Pb in the soils originated from the deposited waste materials as well as traffic-related activities (e.g. wear and tear of tyres, brakes, and engines) at the site. Hg also originated from the deposited waste materials as well as cement production and oil and coal combustion activities in the study area, while As derived from industrial discharges and metal smelting activities. All the zones exhibited very high ecological risk. The carcinogenic and non-carcinogenic health risks posed by the HMs were also above acceptable levels, with children being more vulnerable than adults to these health risks.
KW  - Landfill
KW  - Heavy metals
KW  - Soil contamination
KW  - Geochemical indices
KW  - Multivariate statistical analysis
KW  - Risk assessment
Y1  - 2021
U6  - https://doi.org/10.1016/j.chemosphere.2021.131007
SN  - 0045-6535
SN  - 1879-1298
VL  - 282
PB  - Elsevier
CY  - Amsterdam [u.a.]
ER  - 
TY  - JOUR
A1  - Korges, Maximilian
A1  - Junge, Malte
A1  - Borg, Gregor
A1  - Oberthür, Thomas
T1  - Supergene mobilization and redistribution of platinum-group elements in the Merensky Reef, eastern Bushveld Complex, South Africa
JF  - The Canadian mineralogist
N2  - Near-surface supergene ores of the Merensky Reef in the Bushveld Complex, South Africa, contain economic grades of platinum-group elements, however, these are currently uneconomic due to low recovery rates. This is the first study that investigates the variation in platinum-group elements in pristine and supergene samples of the Merensky Reef from five drill cores from the eastern Bushveld. The samples from the Richmond and Twickenham farms show different degrees of weathering. The whole-rock platinum-group element distribution was studied by inductively coupled plasma-mass spectrometry and the platinum-group minerals were investigated by reflected-light microscopy, scanning electron microscopy, and electron microprobe analysis. <br /> In pristine ("fresh") Merensky Reef samples, platinum-group elements occur mainly as discrete platinum-group minerals, such as platinum-group element-sulfides (cooperite-braggite) and laurite as well as subordinate platinum-group elementbismuthotellurides and platinum-group element-arsenides, and also in solid solution in sulfides (especially Pd in pentlandite). During weathering, Pd and S were removed, resulting in a platinum-group mineral mineralogy in the supergene Merensky Reef that mainly consists of relict platinum-group minerals, Pt-Fe alloys, and Pt-oxides/hydroxides. Additional proportions of platinum-group elements are hosted by Fe-hydroxides and secondary hydrosilicates (e.g., serpentine group minerals and chlorite). <br /> In supergene ores, only low recovery rates (ca. 40%) are achieved due to the polymodal and complex platinum-group element distribution. To achieve higher recovery rates for the platinum-group elements, hydrometallurgical or pyrometallurgical processing of the bulk ore would be required, which is not economically viable with existing technology.
KW  - Bushveld Complex
KW  - Merensky Reef
KW  - PGE
KW  - PGM
KW  - supergene ores
KW  - weathering
Y1  - 2021
U6  - https://doi.org/10.3749/canmin.2100023
SN  - 1499-1276
VL  - 59
IS  - 6
SP  - 1381
EP  - 1396
PB  - Mineralogical Association of Canada
CY  - Ottawa
ER  - 
TY  - JOUR
A1  - Steding, Svenja
A1  - Kempka, Thomas
A1  - Zirkler, Axel
A1  - Kühn, Michael
T1  - Spatial and temporal evolution of leaching zones within potash seams reproduced by reactive transport simulations
JF  - Water / Molecular Diversity Preservation International (MDPI)
N2  - Leaching zones within potash seams generally represent a significant risk to subsurface mining operations and the construction of technical caverns in salt rocks, but their temporal and spatial formation has been investigated only rudimentarily to date. To the knowledge of the authors, current reactive transport simulation implementations are not capable to address hydraulic-chemical interactions within potash salt. For this reason, a reactive transport model has been developed and complemented by an innovative approach to calculate the interchange of minerals and solution at the water-rock interface. Using this model, a scenario analysis was carried out based on a carnallite-bearing potash seam. The results show that the evolution of leaching zones depends on the mineral composition and dissolution rate of the original salt rock, and that the formation can be classified by the dimensionless parameters of Peclet (Pe) and Damkohler (Da). For Pe > 2 and Da > 1, a funnel-shaped leaching zone is formed, otherwise the dissolution front is planar. Additionally, Da > 1 results in the formation of a sylvinitic zone and a flow barrier. Most scenarios represent hybrid forms of these cases. The simulated shapes and mineralogies are confirmed by literature data and can be used to assess the hazard potential.
KW  - carnallite
KW  - water rock interaction
KW  - density-driven flow
KW  - PHREEQC
KW  - Pitzer
KW  - equations
Y1  - 2021
U6  - https://doi.org/10.3390/w13020168
SN  - 2073-4441
VL  - 13
IS  - 2
PB  - Molecular Diversity Preservation International
CY  - Basel
ER  - 
TY  - JOUR
A1  - Tranter, Morgan Alan
A1  - De Lucia, Marco
A1  - Kühn, Michael
T1  - Barite scaling potential modelled for fractured-porous geothermal reservoirs
JF  - Minerals
N2  - Barite scalings are a common cause of permanent formation damage to deep geothermal reservoirs. Well injectivity can be impaired because the ooling of saline fluids reduces the solubility of barite, and the continuous re-injection of supersaturated fluids forces barite to precipitate in the host rock. Stimulated reservoirs in the Upper Rhine Graben often have multiple relevant flow paths in the porous matrix and fracture zones, sometimes spanning multiple stratigraphical units to achieve the economically necessary injectivity. While the influence of barite scaling on injectivity has been investigated for purely porous media, the role of fractures within reservoirs consisting of both fractured and porous sections is still not well understood. Here, we present hydro-chemical simulations of a dual-layer geothermal reservoir to study the long-term impact of barite scale formation on well injectivity. Our results show that, compared to purely porous reservoirs, fractured porous reservoirs have a significantly reduced scaling risk by up to 50%, depending on the flow rate ratio of fractures. Injectivity loss is doubled, however, if the amount of active fractures is increased by one order of magnitude, while the mean fracture aperture is decreased, provided the fractured aquifer dictates the injection rate. We conclude that fractured, and especially hydraulically stimulated, reservoirs are generally less affected by barite scaling and that large, but few, fractures are favourable. We present a scaling score for fractured-porous reservoirs, which is composed of easily derivable quantities such as the radial equilibrium length and precipitation potential. This score is suggested for use approximating the scaling potential and its impact on injectivity of a fractured-porous reservoir for geothermal exploitation.
KW  - reactive transport
KW  - radial flow
KW  - geothermal energy
KW  - injectivity
KW  - phreeqc
KW  - formation damage
Y1  - 2021
U6  - https://doi.org/10.3390/min11111198
SN  - 2075-163X
VL  - 11
IS  - 11
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Runge, Alexandra
A1  - Nitze, Ingmar
A1  - Grosse, Guido
T1  - Remote sensing annual dynamics of rapid permafrost thaw disturbances with LandTrendr
JF  - Remote sensing of environment : an interdisciplinary journal
N2  - Permafrost is warming globally which leads to widespread permafrost thaw. Particularly ice-rich permafrost is vulnerable to rapid thaw and erosion, impacting whole landscapes and ecosystems. Retrogressive thaw slumps (RTS) are abrupt permafrost disturbances that expand by several meters each year and lead to an increased soil organic carbon release. Local Remote Sensing studies identified increasing RTS activity in the last two decades by increasing number of RTS or heightened RTS growth rates. However, a large-scale assessment across diverse permafrost regions and at high temporal resolution allowing to further determine RTS thaw dynamics and its main drivers is still lacking. In this study we apply the disturbance detection algorithm LandTrendr for automated large-scale RTS mapping and high temporal thaw dynamic assessment to North Siberia (8.1 x 106km2). We adapted and parametrised the temporal segmentation algorithm for abrupt disturbance detection to incorporate Landsat+Sentinel-2 mosaics, conducted spectral filtering, spatial masking and filtering, and a binary machine-learning object classification of the disturbance output to separate between RTS and false positives (F1 score: 0.609). Ground truth data for calibration and validation of the workflow was collected from 9 known RTS cluster sites using very highresolution RapidEye and PlanetScope imagery. Our study presents the first automated detection and assessment of RTS and their temporal dynamics at largescale for 2001-2019. We identified 50,895 RTS and a steady increase in RTS-affected area from 2001 to 2019 across North Siberia, with a more abrupt increase from 2016 onward. Overall the RTS-affected area increased by 331% compared to 2000 (2000: 20,158 ha, 2001-2019: 66,699 ha). Contrary to this, 5 focus sites show spatiotemporal variability in their annual RTS dynamics, with alternating periods of increased and decreased RTS development, indicating a close relationship to thaw drivers. The majority of identified RTS was active from 2000 onward and only a small proportion initiated during the assessment period, indicating that the increase in RTS-affected area was mainly caused by enlarging existing RTS and not by new RTS. The detected increase in RTS dynamics suggests advancing permafrost thaw and underlines the importance of assessing abrupt permafrost disturbances with high spatial and temporal resolution at large-scales. Obtaining such consistent disturbance products will help to parametrise regional and global climate change models.
KW  - retrogressive thaw slumps
KW  - time series
KW  - multi-spectral analysis
KW  - landsat
KW  - sentinel-2
KW  - thermo-erosion
KW  - permafrost thaw
Y1  - 2021
U6  - https://doi.org/10.1016/j.rse.2021.112752
SN  - 0034-4257
SN  - 1879-0704
VL  - 268
PB  - Elsevier
CY  - New York
ER  - 
TY  - JOUR
A1  - Altenberger, Uwe
A1  - Cisterna, Clara
A1  - Günter, Christina
A1  - Gutiérrez, Adolfo Antonio
A1  - Rosales, J.
T1  - Tectono-metamorphic evolution of the proto-Andean margin of Gondwana
BT  - Evidence of internal high-grade metamorphism along the northern portion of the Famatinian orogen, Sierra de Aconquija, Sierras Pampeanas Orientales, Argentina
JF  - Journal of South American earth sciences
N2  - The present work gives a detailed analysis of the metamorphic and structural evolution of the back-arc portion of the Famatinian Orogen exposed in the southern Sierra de Aconquija (Cuesta de La Chilca segment) in the Sierras Pampeanas Orientales (Eastern Pampean Sierras). The Pampeanas Orientales include from north to south the Aconquija, Ambato and Ancasti mountains. They are mainly composed of middle to high grade metasedimentary units and magmatic rocks. 
At the south end of the Sierra de Aconquija, along an east to west segment extending over nearly 10 km (Cuesta de La Chilca), large volumes of metasedimentary rocks crop out. The eastern metasediments were defined as members of the El Portezuelo Metamorphic-Igneous Complex (EPMIC) or Eastern block and the western ones relate to the Quebrada del Molle Metamorphic Complex (QMMC) or Western block. The two blocks are divided by the La Chilca Shear Zone, which is reactivated as the Rio Chanarito fault. 
The EPMIC, forming the hanging wall, is composed of schists, gneisses and rare amphibolites, calc- silicate schists, marbles and migmatites. The rocks underwent multiple episodes of deformation and a late high strain-rate episode with gradually increasing mylonitization to the west. Metamorphism progrades from a M-1 phase to the peak M-3, characterized by the reactions: Qtz + Pl + Bt +/- Ms -> Grt + Bt(2) + Pl(2) +/- Sil +/- Kfs, Qtz + Bt + Sil -> Crd + Kfs and Qtz + Grt + Sil -> Crd. The M-3 assemblage is coeval with the dominant foliation related to a third deformational phase (D-3). 

The QMMC, forming the foot wall, is made up of fine-grained banded quartz - biotite schists with quartz veins and quartz-feldspar-rich pegmatites. To the east, schists are also overprinted by mylonitization. The M-3 peak assemblage is quartz + biotite + plagioclase +/- garnet +/- sillimanite +/- muscovite +/- ilmenite +/- magnetite +/- apatite. 

The studied segment suffered multiphase deformation and metamorphism. Some of these phases can be correlated between both blocks. D-1 is locally preserved in scarce outcrops in the EPMIC but is the dominant in the QMMC, where S-1 is nearly parallel to S-0. In the EPMIC, D-2 is represented by the S-2 foliation, related to the F-2 folding that overprints S-1, with dominant strike NNW - SSE and high angles dip to the E. D-3 in the EPMIC have F-3 folds with axis oblique to S-2; the S-3 foliation has striking NW - SE dipping steeply to the E or W and develops interference patterns. In the QMMC, S-2 (D-2) is a discontinuous cleavage oblique to S-1 and transposed by S-3 (D-3), subparallel to S-1. Such structures in the QMMC developed at subsolidus conditions and could be correlated to those of the EPMIC, which formed under higher P-T conditions. The penetrative deformation D-2 in the EPMIC occurred during a prograde path with syntectonic growth of garnet reaching P-T conditions of 640 degrees C and 0.54 GPa in the EPMIC. This stage was followed by a penetrative deformation D-3 with syn-kinematic growth of garnet, cordierite and plagioclase. Peak P-T conditions calculated for M-3 are 710 degrees C and 0.60 GPa, preserved in the western part of the EPMIC, west of the unnamed fault.
The schists from the QMMC suffered the early low grade M-1 metamorphism with minimum PT conditions of ca 400 degrees C and 0.35 GPa, comparable to the fine schists (M-1) outcropping to the east. The D-2 deformation is associated with the prograde M-2 metamorphism. The penetrative D-3 stage is related to a medium grade metamorphism M-3, with peak conditions at ca 590 degrees C and 0.55 GPa.
The superimposed stages of deformation and metamorphism reaching high P-T conditions followed by isothermal decompression, defining a clockwise orogenic P-T path. During the Lower Paleozoic, folds were superimposed and recrystallization as well as partial melting at peak conditions occurred. Similar characteristics were described from the basement from other Famatinian-dominated locations of the Sierra de Aconquija and other ranges of the Sierras Pampeanas Orientales.
KW  - Famatinian
KW  - Sierras Pampeanas Orientales
KW  - Cuesta de la chilca
KW  - PT path
Y1  - 2021
U6  - https://doi.org/10.1016/j.jsames.2021.103305
SN  - 0895-9811
VL  - 110
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Esfahani, Reza Dokht Dolatabadi
A1  - Vogel, Kristin
A1  - Cotton, Fabrice Pierre
A1  - Ohrnberger, Matthias
A1  - Scherbaum, Frank
A1  - Kriegerowski, Marius
T1  - Exploring the dimensionality of ground-motion data by applying autoencoder techniques
JF  - Bulletin of the Seismological Society of America : BSSA
N2  - In this article, we address the question of how observed ground-motion data can most effectively be modeled for engineering seismological purposes. Toward this goal, we use a data-driven method, based on a deep-learning autoencoder with a variable number of nodes in the bottleneck layer, to determine how many parameters are needed to reconstruct synthetic and observed ground-motion data in terms of their median values and scatter. The reconstruction error as a function of the number of nodes in the bottleneck is used as an indicator of the underlying dimensionality of ground-motion data, that is, the minimum number of predictor variables needed in a ground-motion model. Two synthetic and one observed datasets are studied to prove the performance of the proposed method. We find that mapping ground-motion data to a 2D manifold primarily captures magnitude and distance information and is suited for an approximate data reconstruction. The data reconstruction improves with an increasing number of bottleneck nodes of up to three and four, but it saturates if more nodes are added to the bottleneck.
Y1  - 2021
U6  - https://doi.org/10.1785/0120200285
SN  - 0037-1106
SN  - 1943-3573
VL  - 111
IS  - 3
SP  - 1563
EP  - 1576
PB  - Seismological Society of America
CY  - El Cerito, Calif.
ER  - 
TY  - JOUR
A1  - Soergel, Bjoern
A1  - Kriegler, Elmar
A1  - Weindl, Isabelle
A1  - Rauner, Sebastian
A1  - Dirnaichner, Alois
A1  - Ruhe, Constantin
A1  - Hofmann, Matthias
A1  - Bauer, Nico
A1  - Bertram, Christoph
A1  - Bodirsky, Benjamin Leon
A1  - Leimbach, Marian
A1  - Leininger, Julia
A1  - Levesque, Antoine
A1  - Luderer, Gunnar
A1  - Pehl, Michaja
A1  - Wingens, Christopher
A1  - Baumstark, Lavinia
A1  - Beier, Felicitas
A1  - Dietrich, Jan Philipp
A1  - Humpenöder, Florian
A1  - von Jeetze, Patrick
A1  - Klein, David
A1  - Koch, Johannes
A1  - Pietzcker, Robert C.
A1  - Strefler, Jessica
A1  - Lotze-Campen, Hermann
A1  - Popp, Alexander
T1  - A sustainable development pathway for climate action within the UN 2030 Agenda
JF  - Nature climate change
N2  - Ambitious climate policies, as well as economic development, education, technological progress and less resource-intensive lifestyles, are crucial elements for progress towards the UN Sustainable Development Goals (SDGs). However, using an integrated modelling framework covering 56 indicators or proxies across all 17 SDGs, we show that they are insufficient to reach the targets. An additional sustainable development package, including international climate finance, progressive redistribution of carbon pricing revenues, sufficient and healthy nutrition and improved access to modern energy, enables a more comprehensive sustainable development pathway. We quantify climate and SDG outcomes, showing that these interventions substantially boost progress towards many aspects of the UN Agenda 2030 and simultaneously facilitate reaching ambitious climate targets. Nonetheless, several important gaps remain; for example, with respect to the eradication of extreme poverty (180 million people remaining in 2030). These gaps can be closed by 2050 for many SDGs while also respecting the 1.5 °C target and several other planetary boundaries.
KW  - climate-change mitigation
KW  - climate-change policy
KW  - socioeconomic scenarios
KW  - sustainability
Y1  - 2021
U6  - https://doi.org/10.1038/s41558-021-01098-3
SN  - 1758-678X
SN  - 1758-6798
VL  - 11
IS  - 8
SP  - 656
EP  - 664
PB  - Nature Publishing Group
CY  - London
ER  - 
TY  - JOUR
A1  - Barbot, Sylvain
A1  - Weiss, Jonathan R.
T1  - Connecting subduction, extension and shear localization across the Aegean Sea and Anatolia
JF  - Geophysical journal international
N2  - The Eastern Mediterranean is the most seismically active region in Europe due to the complex interactions of the Arabian, African, and Eurasian tectonic plates. Deformation is achieved by faulting in the brittle crust, distributed flow in the viscoelastic lower-crust and mantle, and Hellenic subduction, but the long-term partitioning of these mechanisms is still unknown. We exploit an extensive suite of geodetic observations to build a kinematic model connecting strike-slip deformation, extension, subduction, and shear localization across Anatolia and the Aegean Sea by mapping the distribution of slip and strain accumulation on major active geological structures. We find that tectonic escape is facilitated by a plate-boundary-like, translithospheric shear zone extending from the Gulf of Evia to the Turkish-Iranian Plateau that underlies the surface trace of the North Anatolian Fault. Additional deformation in Anatolia is taken up by a series of smaller-scale conjugate shear zones that reach the upper mantle, the largest of which is located beneath the East Anatolian Fault. Rapid north-south extension in the western part of the system, driven primarily by Hellenic Trench retreat, is accommodated by rotation and broadening of the North Anatolian mantle shear zone from the Sea of Marmara across the north Aegean Sea, and by a system of distributed transform faults and rifts including the rapidly extending Gulf of Corinth in central Greece and the active grabens of western Turkey. Africa-Eurasia convergence along the Hellenic Arc occurs at a median rate of 49.8mm yr(-1) in a largely trench-normal direction except near eastern Crete where variably oriented slip on the megathrust coincides with mixed-mode and strike-slip deformation in the overlying accretionary wedge near the Ptolemy-Pliny-Strabo trenches. Our kinematic model illustrates the competing roles the North Anatolian mantle shear zone, Hellenic Trench, overlying mantle wedge, and active crustal faults play in accommodating tectonic indentation, slab rollback and associated Aegean extension. Viscoelastic flow in the lower crust and upper mantle dominate the surface velocity field across much of Anatolia and a clear transition to megathrust-related slab pull occurs in western Turkey, the Aegean Sea and Greece. Crustal scale faults and the Hellenic wedge contribute only a minor amount to the large-scale, regional pattern of Eastern Mediterranean interseismic surface deformation.
KW  - Seismic cycle
KW  - Space geodetic surveys
KW  - Europe
KW  - Joint inversion
KW  - Kinematics of crustal and mantle deformation
KW  - Rheology: crust and
KW  - lithosphere
Y1  - 2021
U6  - https://doi.org/10.1093/gji/ggab078
SN  - 0956-540X
SN  - 1365-246X
VL  - 226
IS  - 1
SP  - 422
EP  - 445
PB  - Blackwell
CY  - Oxford [u.a.]
ER  - 
TY  - JOUR
A1  - Körting, Friederike Magdalena
A1  - Köllner, Nicole
A1  - Kuras, Agnieszka
A1  - Bösche, Nina Kristin
A1  - Rogass, Christian
A1  - Mielke, Christian
A1  - Elger, Kirsten
A1  - Altenberger, Uwe
T1  - A solar optical hyperspectral library of rare-earth-bearing minerals, rare-earth oxide powders, copper-bearing minerals and Apliki mine surface samples
JF  - Earth system science data : ESSD
N2  - Mineral resource exploration and mining is an essential part of today's high-tech industry. Elements such as rare-earth elements (REEs) and copper are, therefore, in high demand. Modern exploration techniques from multiple platforms (e.g., spaceborne and airborne), to detect and map the spectral characteristics of the materials of interest, require spectral libraries as an essential reference. They include field and laboratory spectral information in combination with geochemical analyses for validation. Here, we present a collection of REE- and copper-related hyperspectral spectra with associated geochemical information. The libraries contain reflectance spectra from rare-earth element oxides, REE-bearing minerals, copper-bearing minerals and mine surface samples from the Apliki copper-gold-pyrite mine in the Republic of Cyprus. The samples were measured with the HySpex imaging spectrometers in the visible and near infrared (VNIR) and shortwave infrared (SWIR) range (400-2500 nm). The geochemical validation of each sample is provided with the reflectance spectra. The spectral libraries are openly available to assist future mineral mapping campaigns and laboratory spectroscopic analyses. The spectral libraries and corresponding geochemistry are published via GFZ Data Services with the following DOIs: https://doi.org/10.5880/GFZ.1.4.2019.004 (13 REE-bearing minerals and 16 oxide powders, Koerting et al., 2019a), https://doi.org/10.5880/GFZ.1.4.2019.003 (20 copper-bearing minerals, Koellner et al., 2019), and https://doi.org/10.5880/GFZ.1.4.2019.005 (37 copper-bearing surface material samples from the Apliki coppergold-pyrite mine in Cyprus, Koerting et al., 2019b). All spectral libraries are united and comparable by the internally consistent method of hyperspectral data acquisition in the laboratory.
Y1  - 2021
U6  - https://doi.org/10.5194/essd-13-923-2021
SN  - 1866-3508
SN  - 1866-3516
VL  - 13
SP  - 923
EP  - 942
PB  - Copernics Publications
CY  - Katlenburg-Lindau
ER  - 
TY  - JOUR
A1  - Freisleben, Roland
A1  - Jara-Munoz, Julius
A1  - Melnick, Daniel
A1  - Miguel Martinez, Jose
A1  - Strecker, Manfred
T1  - Marine terraces of the last interglacial period along the Pacific coast of South America (1 degrees N-40 degrees S)
JF  - Earth system science data : ESSD
N2  - Tectonically active coasts are dynamic environments characterized by the presence of multiple marine terraces formed by the combined effects of wave erosion, tectonic uplift, and sea-level oscillations at glacialcycle timescales. Well-preserved erosional terraces from the last interglacial sea-level highstand are ideal marker horizons for reconstructing past sea-level positions and calculating vertical displacement rates. We carried out an almost continuous mapping of the last interglacial marine terrace along similar to 5000 km of the western coast of South America between 1 degrees N and 40 degrees S. We used quantitatively replicable approaches constrained by published terrace-age estimates to ultimately compare elevations and patterns of uplifted terraces with tectonic and climatic parameters in order to evaluate the controlling mechanisms for the formation and preservation of marine terraces and crustal deformation. Uncertainties were estimated on the basis of measurement errors and the distance from referencing points. Overall, our results indicate a median elevation of 30.1 m, which would imply a median uplift rate of 0.22 m kyr(-1) averaged over the past similar to 125 kyr. The patterns of terrace elevation and uplift rate display high-amplitude (similar to 100-200 m) and long-wavelength (similar to 10(2) km) structures at the Manta Peninsula (Ecuador), the San Juan de Marcona area (central Peru), and the Arauco Peninsula (south-central Chile). Medium-wavelength structures occur at the Mejillones Peninsula and Topocalma in Chile, while short-wavelength (< 10 km) features are for instance located near Los Vilos, Valparaiso, and Carranza, Chile. We interpret the long-wavelength deformation to be controlled by deep-seated processes at the plate interface such as the subduction of major bathymetric anomalies like the Nazca and Carnegie ridges. In contrast, short-wavelength deformation may be primarily controlled by sources in the upper plate such as crustal faulting, which, however, may also be associated with the subduction of topographically less pronounced bathymetric anomalies. Latitudinal differences in climate additionally control the formation and preservation of marine terraces. Based on our synopsis we propose that increasing wave height and tidal range result in enhanced erosion and morphologically well-defined marine terraces in south-central Chile. Our study emphasizes the importance of using systematic measurements and uniform, quantitative methodologies to characterize and correctly interpret marine terraces at regional scales, especially if they are used to unravel the tectonic and climatic forcing mechanisms of their formation. This database is an integral part of the World Atlas of Last Interglacial Shorelines (WALIS), published online at https://doi.org/10.5281/zenodo.4309748 (Freisleben et al., 2020).
Y1  - 2021
U6  - https://doi.org/10.5194/essd-13-2487-2021
SN  - 1866-3508
SN  - 1866-3516
VL  - 13
IS  - 6
SP  - 2487
EP  - 2513
PB  - Copernics Publications
CY  - Katlenburg-Lindau
ER  - 
TY  - JOUR
A1  - Han, Sungju
A1  - Kuhlicke, Christian
T1  - Barriers and drivers for mainstreaming nature-based solutions for flood risks
BT  - the case of South Korea
JF  - International journal of disaster risk science
N2  - Nature-based solutions (NBS) are seen as a promising adaptation measure that sustainably deals with diverse societal challenges, while simultaneously delivering multiple benefits. Nature-based solutions have been highlighted as a resilient and sustainable means of mitigating floods and other hazards globally. This study examined diverging conceptualizations of NBS, as well as the attitudinal (for example, emotions and beliefs) and contextual (for example, legal and political aspects) barriers and drivers of NBS for flood risks in South Korea. Semistructured interviews were conducted with 11 experts and focused on the topic of flood risk measures and NBS case studies. The analysis found 11 barriers and five drivers in the attitudinal domain, and 13 barriers and two drivers in the contextual domain. Most experts see direct monetary benefits as an important attitudinal factor for the public. Meanwhile, the cost-effectiveness of NBS and their capacity to cope with flood risks were deemed influential factors that could lead decision makers to opt for NBS. Among the contextual factors, insufficient systems to integrate NBS in practice and the ideologicalization of NBS policy were found to be peculiar barriers, which hinder consistent realization of initiatives and a long-term national plan for NBS. Understanding the barriers and drivers related to the mainstreaming of NBS is critical if we are to make the most of such solutions for society and nature. It is also essential that we have a shared definition, expectation, and vision of NBS.
KW  - climate change
KW  - flood risk management
KW  - nature-based solutions (NBS)
KW  - South Korea
Y1  - 2021
U6  - https://doi.org/10.1007/s13753-021-00372-4
SN  - 2095-0055
SN  - 2192-6395
VL  - 12
IS  - 5
SP  - 661
EP  - 672
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Hennig, Theresa
A1  - Kühn, Michael
T1  - Potential uranium migration within the geochemical gradient of the opalinus clay system at the Mont Terri
JF  - Minerals
N2  - Transport properties of potential host rocks for nuclear waste disposal are typically determined in laboratory or in-situ experiments under geochemically controlled and constant conditions. Such a homogeneous assumption is no longer applicable on the host rock scale as can be seen from the pore water profiles of the potential host rock Opalinus Clay at Mont Terri (Switzerland). The embedding aquifers are the hydro-geological boundaries, that established gradients in the 210 m thick low permeable section through diffusive exchange over millions of years. Present-day pore water profiles were confirmed by a data-driven as well as by a conceptual scenario. Based on the modelled profiles, the influence of the geochemical gradient on uranium migration was quantified by comparing the distances after one million years with results of common homogeneous models. Considering the heterogeneous system, uranium migrated up to 24 m farther through the formation depending on the source term position within the gradient and on the partial pressure of carbon dioxide pCO2 of the system. Migration lengths were almost equal for single- and multicomponent diffusion. Differences can predominantly be attributed to changes in the sorption capacity, whereby pCO2 governs how strong uranium migration is affected by the geochemical gradient. Thus, the governing parameters for uranium migration in the Opalinus Clay can be ordered in descending priority: pCO2, geochemical gradients, mineralogical heterogeneity.</p>
KW  - PHREEQC
KW  - reactive transport
KW  - sorption
KW  - diffusion
KW  - repository far-field
KW  - hydro-geological system
Y1  - 2021
U6  - https://doi.org/10.3390/min11101087
SN  - 2075-163X
VL  - 11
IS  - 10
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Ghignone, Stefano
A1  - Sudo, Masafumi
A1  - Balestro, Gianni
A1  - Borghi, Alessandro
A1  - Gattiglio, Marco
A1  - Ferrero, Silvio
A1  - Schijndel, Valby van
T1  - Timing of exhumation of meta-ophiolite units in the Western Alps
BT  - New tectonic implications from Ar-40/Ar-39 white mica ages from Piedmont Zone (Susa Valley)
JF  - Lithos : an international journal of mineralogy, petrology, and geochemistry
N2  - A multidisciplinary approach to the study of collisional orogenic belts can improve our knowledge of their geodynamic evolution and may suggest new tectonic models, especially for (U)HP rocks inside the accretionary wedge. In the Western Alps, wherein nappes of different origin are stacked, having recorded different metamorphic peaks at different stages of the orogenic evolution. This study focuses on the External (EPZ) and Internal (IPZ) ophiolitic units of the Piedmont Zone (Susa Valley, Western Alps), which were deformed throughout four tectonometamorphic phases (D1 to D4), developing different foliations and cleavages (S1 to S4) at different metamorphic conditions. The IPZ and EPZ are separated by a shear zone (i.e. the Susa Shear Zone (SSZ)) during which a related mylonitic foliation (SM) developed. S1 developed at high pressure conditions (Epidote-eclogite vs. Lawsonite-blueschist facies conditions for IPZ and EPZ, respectively), as suggested by the composition of white mica (i.e. phengite), whereas S2 developed at low pressure conditions (Epidote-greenschist facies conditions in both IPZ and EPZ) and is defined by muscovite. White mica defining the SM mylonitic foliation (T1) is mostly defined by phengite, while the T2-related disjunctive cleavage is defined by fine-grained muscovite. The relative chronology inferred from meso-and micro-structural observations suggests that T1 was near-coeval with respect to the D2, while T2 developed during D4. A new set of radiometric ages of the main metamorphic foliations were obtained by in situ Ar/Ar dating on white mica. Different generations of white mica defining S1 and S2 foliations in both the IPZ and EPZ and SM in the SSZ, were dated and two main groups of ages were obtained. In both IPZ and EPZ, S1 foliation developed at-46-41 Ma, while S2 foliation developed at-40-36 Ma and was nearly coeval with the SM mylonitic foliation (-39-36 Ma). Comparison between structural, petrological and geochronological data allows to define time of coupling of the different units and consequently to infer new tectonic implications for the exhumation of meta-ophiolites of the Piedmont Zone within axial sector of the Western Alps.
KW  - Exhumation
KW  - meta-ophiolites
KW  - Piedmont Zone
KW  - Western Alps
KW  - Ar-40
KW  - Ar-39
Y1  - 2021
U6  - https://doi.org/10.1016/j.lithos.2021.106443
SN  - 0024-4937
SN  - 1872-6143
VL  - 404-405
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Richter, Maximilian
A1  - Brune, Sascha
A1  - Riedl, Simon
A1  - Glerum, Anne
A1  - Neuharth, Derek
A1  - Strecker, Manfred
T1  - Controls on asymmetric rift dynamics
BT  - Numerical modeling of strain localization and fault evolution in the Kenya Rift
JF  - Tectonics / American Geophysical Union, AGU ; European Geophysical Society, EGS
N2  - Complex, time-dependent, and asymmetric rift geometries are observed throughout the East African Rift System (EARS) and are well documented, for instance, in the Kenya Rift. To unravel asymmetric rifting processes in this region, we conduct 2D geodynamic models. We use the finite element software ASPECT employing visco-plastic rheologies, mesh-refinement, distributed random noise seeding, and a free surface. In contrast to many previous numerical modeling studies that aimed at understanding final rifted margin symmetry, we explicitly focus on initial rifting stages to assess geodynamic controls on strain localization and fault evolution. We thereby link to geological and geophysical observations from the Southern and Central Kenya Rift. Our models suggest a three-stage early rift evolution that dynamically bridges previously inferred fault-configuration phases of the eastern EARS branch: (1) accommodation of initial strain localization by a single border fault and flexure of the hanging-wall crust, (2) faulting in the hanging-wall and increasing upper-crustal faulting in the rift-basin center, and (3) loss of pronounced early stage asymmetry prior to basinward localization of deformation. This evolution may provide a template for understanding early extensional faulting in other branches of the East African Rift and in asymmetric rifts worldwide. By modifying the initial random noise distribution that approximates small-scale tectonic inheritance, we show that a spectrum of first-order fault configurations with variable symmetry can be produced in models with an otherwise identical setup. This approach sheds new light on along-strike rift variability controls in active asymmetric rifts and proximal rifted margins.
KW  - asymmetric rifting
KW  - rift variability
KW  - numerical model
KW  - structural
KW  - inheritance
KW  - Kenya Rift
Y1  - 2021
U6  - https://doi.org/10.1029/2020TC006553
SN  - 0278-7407
SN  - 1944-9194
VL  - 40
IS  - 5
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Hofmann, Hannes
A1  - Blöcher, Guido
A1  - Zang, Arno
T1  - Special issue on rock fracturing and fault activation
BT  - experiments and models selected papers presented at the 13th EURO-Conference on rock physics and geomechanics - the Gueguen Conference Held on 2-6 September 2019 in Potsdam, Germany
JF  - Rock mechanics and rock engineering
Y1  - 2021
U6  - https://doi.org/10.1007/s00603-021-02635-4
SN  - 0723-2632
SN  - 1434-453X
VL  - 54
IS  - 10
SP  - 5149
EP  - 5153
PB  - Springer
CY  - Wien
ER  - 
TY  - JOUR
A1  - Steding, Svenja
A1  - Kempka, Thomas
A1  - Kühn, Michael
T1  - How insoluble inclusions and intersecting layers affect the leaching process within potash seams
JF  - Applied Sciences : open access journal
N2  - Potash seams are a valuable resource containing several economically interesting, but also highly soluble minerals. In the presence of water, uncontrolled leaching can occur, endangering subsurface mining operations. In the present study, the influence of insoluble inclusions and intersecting layers on leaching zone evolution was examined by means of a reactive transport model. For that purpose, a scenario analysis was carried out, considering different rock distributions within a carnallite-bearing potash seam. The results show that reaction-dominated systems are not affected by heterogeneities at all, whereas transport-dominated systems exhibit a faster advance in homogeneous rock compositions. In return, the ratio of permeated rock in vertical direction is higher in heterogeneous systems. Literature data indicate that most natural potash systems are transport-dominated. Accordingly, insoluble inclusions and intersecting layers can usually be seen as beneficial with regard to reducing hazard potential as long as the mechanical stability of leaching zones is maintained. Thereby, the distribution of insoluble areas is of minor impact unless an inclined, intersecting layer occurs that accelerates leaching zone growth in one direction. Moreover, it is found that the saturation dependency of dissolution rates increases the growth rate in the long term, and therefore must be considered in risk assessments.
KW  - salt dissolution
KW  - reactive transport
KW  - heterogeneity
KW  - density-driven
KW  - convection
KW  - PHREEQC
KW  - porous media
Y1  - 2021
U6  - https://doi.org/10.3390/app11199314
SN  - 2076-3417
VL  - 11
IS  - 19
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Pilz, Marco
A1  - Cotton, Fabrice Pierre
A1  - Zhu, Chuanbin
T1  - How much are sites affected by 2-D and 3-D site effects?
BT  - a study based on single-station earthquake records and implications for ground motion modelling
JF  - Geophysical journal international
N2  - 1-D site response analysis dominates earthquake engineering practice, while local 2-D/3-D models are often required at sites where the site response is complex. For such sites, the 1-D representation of the soil column can account neither for topographic effects or dipping layers nor for locally generated horizontally propagating surface waves. It then remains a crucial task to identify whether the site response can be modelled sufficiently precisely by 1-D analysis. In this study we develop a method to classify sites according to their 1-D or 2-D/3-D nature. This classification scheme is based on the analysis of surface earthquake recordings and the evaluation of the variability and similarity of the horizontal Fourier spectra. The taxonomy is focused on capturing significant directional dependencies and interevent variabilities indicating a more probable 2-D/3-D structure around the site causing the ground motion to be more variable. While no significant correlation of the 1-D/3-D site index with environmental parameters and site proxies seems to exist, a reduction in the within-site (single-station) variability is found. The reduction is largest (up to 20 per cent) for purely 1-D sites. Although the taxonomy system is developed using surface stations of the KiK-net network in Japan as considerable additional information is available, it can also be applied to any (non-downhole array) site.
KW  - Earthquake ground motions
KW  - Earthquake hazards
KW  - Site effects
KW  - Wave propagation
Y1  - 2021
U6  - https://doi.org/10.1093/gji/ggab454
SN  - 0956-540X
SN  - 1365-246X
VL  - 228
IS  - 3
SP  - 1992
EP  - 2004
PB  - Oxford University Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Zali, Zahra
A1  - Ohrnberger, Matthias
A1  - Scherbaum, Frank
A1  - Cotton, Fabrice
A1  - Eibl, Eva P. S.
T1  - Volcanic tremor extraction and earthquake detection using music information retrieval algorithms
JF  - Seismological research letters
N2  - Volcanic tremor signals are usually observed before or during volcanic eruptions and must be monitored to evaluate the volcanic activity. A challenge in studying seismic signals of volcanic origin is the coexistence of transient signal swarms and long-lasting volcanic tremor signals. Separating transient events from volcanic tremors can, therefore, contrib-ute to improving upon our understanding of the underlying physical processes. Exploiting the idea of harmonic-percussive separation in musical signal processing, we develop a method to extract the harmonic volcanic tremor signals and to detect tran-sient events from seismic recordings. Based on the similarity properties of spectrogram frames in the time-frequency domain, we decompose the signal into two separate spec-trograms representing repeating (harmonic) and nonrepeating (transient) patterns, which correspond to volcanic tremor signals and earthquake signals, respectively. We reconstruct the harmonic tremor signal in the time domain from the complex spectrogram of the repeating pattern by only considering the phase components for the frequency range in which the tremor amplitude spectrum is significantly contribut-ing to the energy of the signal. The reconstructed signal is, therefore, clean tremor signal without transient events. Furthermore, we derive a characteristic function suitable for the detection of tran-sient events (e.g., earthquakes) by integrating amplitudes of the nonrepeating spectro-gram over frequency at each time frame. Considering transient events like earthquakes, 78% of the events are detected for signal-to-noise ratio = 0.1 in our semisynthetic tests. In addition, we compared the number of detected earthquakes using our method for one month of continuous data recorded during the Holuhraun 2014-2015 eruption in Iceland with the bulletin presented in Agustsdottir et al. (2019). Our single station event detection algorithm identified 84% of the bulletin events. Moreover, we detected a total of 12,619 events, which is more than twice the number of the bulletin events.
KW  - algorithms
KW  - body waves
KW  - earthquakes
KW  - elastic waves
KW  - eruptions
KW  - geologic hazards
KW  - natural hazards
KW  - P-waves
KW  - S-waves
KW  - seismic waves
KW  - signal-to-noise ratio
KW  - swarms
KW  - volcanic earthquakes
Y1  - 2021
U6  - https://doi.org/10.1785/0220210016
SN  - 0895-0695
SN  - 1938-2057
VL  - 92
IS  - 6
SP  - 3668
EP  - 3681
PB  - Seismological Society of America
CY  - Boulder, Colo.
ER  - 
TY  - JOUR
A1  - Jentsch, Anna
A1  - Düsing, Walter
A1  - Jolie, Egbert
A1  - Zimmer, Martin
T1  - Monitoring the response of volcanic CO2 emissions to changes in the Los Humeros hydrothermal system
JF  - Scientific reports
N2  - Carbon dioxide is the most abundant, non-condensable gas in volcanic systems, released into the atmosphere through either diffuse or advective fluid flow. The emission of substantial amounts of CO2 at Earth's surface is not only controlled by volcanic plumes during periods of eruptive activity or fumaroles, but also by soil degassing along permeable structures in the subsurface. Monitoring of these processes is of utmost importance for volcanic hazard analyses, and is also relevant for managing geothermal resources. Fluid-bearing faults are key elements of economic value for geothermal power generation. Here, we describe for the first time how sensitively and quickly natural gas emissions react to changes within a deep hydrothermal system due to geothermal fluid reinjection. For this purpose, we deployed an automated, multi-chamber CO2 flux monitoring system within the damage zone of a deep-rooted major normal fault in the Los Humeros Volcanic Complex (LHVC) in Mexico and recorded data over a period of five months. After removing the atmospheric effects on variations in CO2 flux, we calculated correlation coefficients between residual CO2 emissions and reinjection rates, identifying an inverse correlation of rho = - 0.51 to - 0.66. Our results indicate that gas emissions respond to changes in reinjection rates within 24 h, proving an active hydraulic communication between the hydrothermal system and Earth's surface. This finding is a promising indication not only for geothermal reservoir monitoring but also for advanced long-term volcanic risk analysis. Response times allow for estimation of fluid migration velocities, which is a key constraint for conceptual and numerical modelling of fluid flow in fracture-dominated systems.
KW  - Energy and society
KW  - Geochemistry
KW  - Geology
KW  - Geophysics
KW  - Volcanology
Y1  - 2021
U6  - https://doi.org/10.1038/s41598-021-97023-x
SN  - 2045-2322
VL  - 11
IS  - 1
PB  - Macmillan Publishers Limited, part of Springer Nature
CY  - [London]
ER  - 
TY  - JOUR
A1  - De Lucia, Marco
A1  - Kühn, Michael
A1  - Lindemann, Alexander
A1  - Lübke, Max
A1  - Schnor, Bettina
T1  - POET (v0.1): speedup of many-core parallel reactive transport simulations with fast DHT lookups
JF  - Geoscientific model development : an interactive open access journal of the European Geosciences Union
N2  - Coupled reactive transport simulations are extremely demanding in terms of required computational power, which hampers their application and leads to coarsened and oversimplified domains. The chemical sub-process represents the major bottleneck: its acceleration is an urgent challenge which gathers increasing interdisciplinary interest along with pressing requirements for subsurface utilization such as spent nuclear fuel storage, geothermal energy and CO2 storage. In this context we developed POET (POtsdam rEactive Transport), a research parallel reactive transport simulator integrating algorithmic improvements which decisively speed up coupled simulations. In particular, POET is designed with a master/worker architecture, which ensures computational efficiency in both multicore and cluster compute environments. POET does not rely on contiguous grid partitions for the parallelization of chemistry but forms work packages composed of grid cells distant from each other. Such scattering prevents particularly expensive geochemical simulations, usually concentrated in the vicinity of a reactive front, from generating load imbalance between the available CPUs (central processing units), as is often the case with classical partitions. Furthermore, POET leverages an original implementation of the distributed hash table (DHT) mechanism to cache the results of geochemical simulations for further reuse in subsequent time steps during the coupled simulation. The caching is hence particularly advantageous for initially chemically homogeneous simulations and for smooth reaction fronts. We tune the rounding employed in the DHT on a 2D benchmark to validate the caching approach, and we evaluate the performance gain of POET's master/worker architecture and the DHT speedup on a 3D benchmark comprising around 650 000 grid elements. The runtime for 200 coupling iterations, corresponding to 960 simulation days, reduced from about 24 h on 11 workers to 29 min on 719 workers. Activating the DHT reduces the runtime further to 2 h and 8 min respectively. Only with these kinds of reduced hardware requirements and computational costs is it possible to realistically perform the longterm complex reactive transport simulations, as well as perform the uncertainty analyses required by pressing societal challenges connected with subsurface utilization.
Y1  - 2021
U6  - https://doi.org/10.5194/gmd-14-7391-2021
SN  - 1991-959X
SN  - 1991-9603
VL  - 14
IS  - 12
SP  - 7391
EP  - 7409
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Kreibich, Heidi
A1  - Hudson, Paul
A1  - Merz, Bruno
T1  - Knowing what to do substantially improves the effectiveness of flood early warning
JF  - Bulletin of the American Meteorological Society
N2  - Flood warning systems are longstanding success stories with respect to protecting human life, but monetary losses continue to grow. Knowledge on the effectiveness of flood early warning in reducing monetary losses is scarce, especially at the individual level. To gain more knowledge in this area, we analyze a dataset that is unique with respect to detailed information on warning reception and monetary losses at the property level and with respect to amount of data available. The dataset contains 4,468 loss cases from six flood events in Germany. These floods occurred between 2002 and 2013. The data from each event were collected by computer-aided telephone interviews in four surveys following a repeated cross-sectional design. We quantitatively reveal that flood early warning is only effective in reducing monetary losses when people know what to do when they receive the warning. We also show that particularly long-term preparedness is associated with people knowing what to do when they receive a warning. Thus, risk communication, training, and (financial) support for private preparedness are effective in mitigating flood losses in two ways: precautionary measures and more effective emergency responses.
KW  - adaptation
KW  - damage assessment
KW  - emergency preparedness
KW  - emergency
KW  - response
KW  - flood events
Y1  - 2021
U6  - https://doi.org/10.1175/BAMS-D-20-0262.1
SN  - 0003-0007
SN  - 1520-0477
VL  - 102
IS  - 7
SP  - E1450
EP  - E1463
PB  - American Meteorological Soc.
CY  - Boston
ER  - 
TY  - JOUR
A1  - Rudolph-Mohr, Nicole
A1  - Bereswill, Sarah
A1  - Tötzke, Christian
A1  - Kardjilov, Nikolay
A1  - Oswald, Sascha
T1  - Neutron computed laminography yields 3D root system architecture and complements investigations of spatiotemporal rhizosphere patterns
JF  - Plant and soil
N2  - Purpose
Root growth, respiration, water uptake as well as root exudation induce biogeochemical patterns in the rhizosphere that can change dynamically over time. Our aim is to develop a method that provides complementary information on 3D root system architecture and biogeochemical gradients around the roots needed for the quantitative description of rhizosphere processes. 

Methods
We captured for the first time the root system architecture of maize plants grown in rectangular rhizotrons in 3D using neutron computed laminography (NCL). Simultaneously, we measured pH and oxygen concentration using fluorescent optodes and the 2D soil water distribution by means of neutron radiography. We co-registered the 3D laminography data with the 2D oxygen and pH maps to analyze the sensor signal as a function of the distance between the roots and the optode. 

Results 
The 3D root system architecture was successfully segmented from the laminographic data. We found that exudation of roots in up to 2 mm distance to the pH optode induced patterns of local acidification or alkalization. Over time, oxygen gradients in the rhizosphere emerged for roots up to a distance of 7.5 mm. 

Conclusion 
Neutron computed laminography allows for a three-dimensional investigation of root systems grown in laterally extended rhizotrons as the ones designed for 2D optode imaging studies. The 3D information on root position within the rhizotrons derived by NCL explained measured 2D oxygen and pH distribution. The presented new combination of 3D and 2D imaging methods facilitates systematical investigations of a wide range of dynamic processes in the rhizosphere.
KW  - laminography
KW  - neutron imaging
KW  - rhizosphere biogeochemistry
KW  - 3D root
KW  - system architecture
KW  - root-soil interaction
KW  - root activity
Y1  - 2021
U6  - https://doi.org/10.1007/s11104-021-05120-7
SN  - 0032-079X
SN  - 1573-5036
VL  - 469
IS  - 1-2
SP  - 489
EP  - 501
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Tranter, Morgan Alan
A1  - De Lucia, Marco
A1  - Kühn, Michael
T1  - Numerical investigation of barite scaling kinetics in fractures
JF  - Geothermics : an international journal of geothermal research and its applications
N2  - Barite stands out as one of the most ubiquitous scaling agents in deep geothermal systems, responsible for irreversible efficiency loss. Due to complex parameter interplay, it is imperative to utilise numerical simulations to investigate temporal and spatial precipitation effects. A one-dimensional reactive transport model is set up with heterogeneous nucleation and crystal growth kinetics. In line with geothermal systems in the North German Basin, the following parameters are considered in a sensitivity analysis: temperature (25 to 150 degrees C), pore pressure (10 to 50 MPa), fracture aperture (10(-4) to 10(-2) m), flow velocity (10(-3) to 10(0) m s(-1)), molar volume (50.3 to 55.6 cm(3) mol(-1)), contact angle for heterogeneous nucleation (0 degrees to 180 degrees), interfacial tension (0.07 to 0.134 J m(-2)), salinity (0.1 to 1.5 mol kgw(-1) NaCl), pH (5 to 7), and supersaturation ratio (1 to 30). Nucleation and consequently crystal growth can only begin if the threshold supersaturation is exceeded, therefore contact angle and interfacial tension are the most sensitive in terms of precipitation kinetics. If nucleation has occurred, crystal growth becomes the dominant process, which is mainly controlled by fracture aperture. Results show that fracture sealing takes place within months (median 33 days) and the affected range can be on the order of tens of metres (median 10 m). The presented models suggest that barite scaling must be recognised as a serious threat if the supersaturation threshold is exceeded, in which case, large fracture apertures could help to minimise kinetic rates. The models further are of use for adjusting the fluid injection temperature.
KW  - Geothermal
KW  - Fracture sealing
KW  - Reactive transport
KW  - Geochemical modelling
KW  - Crystal nucleation
KW  - PHREEQC
Y1  - 2021
SN  - 0375-6505
SN  - 1879-3576
VL  - 91
PB  - Elsevier
CY  - Amsterdam [u.a.]
ER  - 
TY  - JOUR
A1  - Mantiloni, Lorenzo
A1  - Davis, Timothy
A1  - Gaete Rojas, Ayleen Barbara
A1  - Rivalta, Eleonora
T1  - Stress inversion in a gelatin box
BT  - testing eruptive vent location forecasts with analog models
JF  - Geophysical research letters : GRL / American Geophysical Union
N2  - Assessing volcanic hazard in regions of distributed volcanism is challenging because of the uncertain location of future vents. A statistical-mechanical strategy to forecast such locations was recently proposed: here, we further develop and test it with analog models. We stress a gelatin block laterally and with surface excavations, and observe air-filled crack trajectories. We use the observed surface arrivals to sample the distributions of parameters describing the stress state of the gelatin block, combining deterministic crack trajectory simulations with a Monte Carlo approach. While the individual stress parameters remain unconstrained, we effectively retrieve their ratio and successfully forecast the arrival points of subsequent cracks.
KW  - analog experiment
KW  - calderas
KW  - continental rifts
KW  - dike propagation
KW  - dike
KW  - trajectories
KW  - stress field
Y1  - 2021
U6  - https://doi.org/10.1029/2020GL090407
SN  - 0094-8276
SN  - 1944-8007
VL  - 48
IS  - 6
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Nicoli, Gautier
A1  - Ferrero, Silvio
T1  - Nanorocks, volatiles and plate tectonics
JF  - Geoscience frontiers
N2  - The global geological volatile cycle (H, C, N) plays an important role in the long term self-regulation of the Earth system. However, the complex interaction between its deep, solid Earth components (i.e. crust and mantle), Earth's fluid envelopes (i.e. atmosphere and hydrosphere) and plate tectonic processes is a subject of ongoing debate. In this study we want to draw attention to how the presence of primary melt (MI) and fluid (FI) inclusions in high-grade metamorphic minerals could help constrain the crustal component of the volatile cycle. To that end, we review the distribution of MI and FI throughout Earth's history, from ca. 3.0 Ga ago up to the present day. We argue that the lower crust might constitute an important, long-term, volatile storage unit, capable to influence the composition of the surface envelopes through the mean of weathering, crustal thickening, partial melting and crustal assimilation during volcanic activity. Combined with thermodynamic modelling, our compilation indicates that periods of well-established plate tectonic regimes at <0.85 Ga and 1.7-2.1 Ga, might be more prone to the reworking of supracrustal lithologies and the storage of volatiles in the lower crust. Such hypothesis has implication beyond the scope of metamorphic petrology as it potentially links geodynamic mechanisms to habitable surface conditions. MI and FI in metamorphic crustal rocks then represent an invaluable archive to assess and quantify the co-joint evolution of plate tectonics and Earth's external processes. (C) 2021 China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
KW  - Nanorocks
KW  - Plate tectonics
KW  - Volatiles
KW  - Lower crust
Y1  - 2021
U6  - https://doi.org/10.1016/j.gsf.2021.101188
SN  - 1674-9871
VL  - 12
IS  - 5
PB  - Amsterdam [u.a.]
CY  - Elsevier
ER  - 
TY  - JOUR
A1  - Hennig, Theresa
A1  - Kühn, Michael
T1  - Surrogate model for multi-component diffusion of Uranium through Opalinus Clay on the host rock scale
JF  - Applied Sciences : open access journal
N2  - Multi-component (MC) diffusion simulations enable a process based and more precise approach to calculate transport and sorption compared to the commonly used single-component (SC) models following Fick's law. The MC approach takes into account the interaction of chemical species in the porewater with the diffuse double layer (DDL) adhering clay mineral surfaces. We studied the shaly, sandy and carbonate-rich facies of the Opalinus Clay. High clay contents dominate diffusion and sorption of uranium. The MC simulations show shorter diffusion lengths than the SC models due to anion exclusion from the DDL. This hampers diffusion of the predominant species CaUO2(CO3)32-. On the one side, species concentrations and ionic strengths of the porewater and on the other side surface charge of the clay minerals control the composition and behaviour of the DDL. For some instances, it amplifies the diffusion of uranium. We developed a workflow to transfer computationally intensive MC simulations to SC models via calibrated effective diffusion and distribution coefficients. Simulations for one million years depict maximum uranium diffusion lengths between 10 m and 35 m. With respect to the minimum requirement of a thickness of 100 m, the Opalinus Clay seems to be a suitable host rock for nuclear waste repositories.
KW  - facies
KW  - uranium speciation
KW  - sorption
KW  - reactive transport
KW  - heterogeneity
KW  - PHREEQC
KW  - Mont Terri
KW  - repository far-field
Y1  - 2021
U6  - https://doi.org/10.3390/app11020786
SN  - 2076-3417
VL  - 11
IS  - 2
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Ozturk, Ugur
A1  - Pittore, Massimiliano
A1  - Behling, Robert
A1  - Rößner, Sigrid
A1  - Andreani, Louis
A1  - Korup, Oliver
T1  - How robust are landslide susceptibility estimates?
JF  - Landslides
N2  - Much of contemporary landslide research is concerned with predicting and mapping susceptibility to slope failure. Many studies rely on generalised linear models with environmental predictors that are trained with data collected from within and outside of the margins of mapped landslides. Whether and how the performance of these models depends on sample size, location, or time remains largely untested. We address this question by exploring the sensitivity of a multivariate logistic regression-one of the most widely used susceptibility models-to data sampled from different portions of landslides in two independent inventories (i.e. a historic and a multi-temporal) covering parts of the eastern rim of the Fergana Basin, Kyrgyzstan. We find that considering only areas on lower parts of landslides, and hence most likely their deposits, can improve the model performance by >10% over the reference case that uses the entire landslide areas, especially for landslides of intermediate size. Hence, using landslide toe areas may suffice for this particular model and come in useful where landslide scars are vague or hidden in this part of Central Asia. The model performance marginally varied after progressively updating and adding more landslides data through time. We conclude that landslide susceptibility estimates for the study area remain largely insensitive to changes in data over about a decade. Spatial or temporal stratified sampling contributes only minor variations to model performance. Our findings call for more extensive testing of the concept of dynamic susceptibility and its interpretation in data-driven models, especially within the broader framework of landslide risk assessment under environmental and land-use change.
KW  - Landslide susceptibility
KW  - Logistic regression
KW  - Southern Kyrgyzstan
KW  - Landslide inventory
KW  - Remote sensing
Y1  - 2020
U6  - https://doi.org/10.1007/s10346-020-01485-5
SN  - 1612-510X
SN  - 1612-5118
VL  - 18
IS  - 2
SP  - 681
EP  - 695
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Roud, Sophie
A1  - Wack, Michael Richard
A1  - Gilder, Stuart A.
A1  - Kudriavtseva, Anna
A1  - Sobel, Edward
T1  - Miocene to early pleistocene depositional history and tectonic evolution of the Issyk-Kul Basin, Central Tian Shan
JF  - Geochemistry, geophysics, geosystems : G 3 ; an electronic journal of the earth sciences
N2  - The Issyk-Kul Basin (Kyrgyzstan), situated in the central Tian Shan Mountains, hosts the largest and deepest mountain lake in Central Asia. Erosion of the surrounding Terskey and Kungey ranges led to the accumulation of up to 4 km of sediment in the adjacent depression. Creation of the basin from regional shortening and uplift likely initiated around the Oligocene-Miocene, yet precise age control is sparse. To better understand the timing of these processes, we obtained magnetostratigraphic age constraints on fossil-poor, fluvio-lacustrine sediments exposed south of Lake Issyk-Kul, that agree well with previous age constraints of the equivalent strata outside the Issyk-Kul Basin. Two 500-650 m thick sections comprised mainly of Chu Group sediments were dated at 6.3-2.8 Ma and 7.0-2.4 Ma (late Miocene to early Pleistocene). Together with reinterpreted magnetostratigraphic constraints from underlying strata, we find that syn-tectonic deposition commenced at similar to 22 Ma with average sedimentation rates <10 cm/ka. Sedimentation rates increased to 10-30 cm/ka at 7 Ma, concurrent with accelerated uplift in the Terskey Range to the south. A deformation event in one section (Kaji-Say) between 5 and 3 Ma together with concurrent shifts of depositional centers throughout the basin signal the onset of substantial uplift of the Kungey Range to the north at similar to 5 Ma. This uplift and deformation transformed the Issyk-Kul area into a closed basin that facilitated the formation of a deep lake. Lacustrine facies deposited around 3 Ma mark the existence of Lake Issyk-Kul by that time.
KW  - Central Asia
KW  - Lake Issyk‐ Kul
KW  - magnetostratigraphy
KW  - Neogene
KW  - Tian
KW  - Shan
Y1  - 2021
U6  - https://doi.org/10.1029/2020GC009556
SN  - 1525-2027
VL  - 22
IS  - 4
PB  - Wiley
CY  - Hoboken, NJ
ER  - 
TY  - JOUR
A1  - Niemz, Peter
A1  - Dahm, Torsten
A1  - Milkereit, Claus
A1  - Cesca, Simone
A1  - Petersen, Gesa Maria
A1  - Zang, Arno
T1  - Insights into hydraulic fracture growth gained from a joint analysis of seismometer-derived tilt signals and scoustic emissions
JF  - Journal of geophysical research : Solid earth
N2  - Hydraulic fracturing is performed to enhance rock permeability, for example, in the frame of geothermal energy production or shale gas exploitation, and can potentially trigger induced seismicity. The tracking of increased permeabilities and the fracturing extent is often based on the microseismic event distribution within the stimulated rock volume, but it is debated whether the microseismic activity adequately depicts the fracture formation. We are able to record tilt signals that appear as long-period transients (<180 s) on two broadband seismometers installed close (17-72 m) to newly formed, meter-scale hydraulic fractures. With this observation, we can overcome the limitations of the microseismic monitoring alone and verify the fracture mapping. Our analysis for the first time combines a catalog of previously analyzed acoustic emissions ([AEs] durations of 20 ms), indirectly mapping the fractures, with unique tilt signals, that provide independent, direct insights into the deformation of the rock. The analysis allows to identify different phases of the fracturing process including the (re)opening, growth, and aftergrowth of fractures. Further, it helps to differentiate between the formation of complex fracture networks and single macrofractures, and it validates the AE fracture mapping. Our findings contribute to a better understanding of the fracturing processes, which may help to reduce fluid-injection-induced seismicity and validate efficient fracture formation. <br /> Plain Language Summary Hydraulic fracturing (HF) describes the opening of fractures in rocks by injecting fluids under high pressure. The new fractures not only can facilitate the extraction of shale gas but can also be used to heat up water in the subsurface in enhanced geothermal systems, a corner stone of renewable energy production. The fracture formation is inherently accompanied by small, nonfelt earthquakes (microseismic events). Occasionally, larger events felt by the population can be induced by the subsurface operations. Avoiding such events is important for the acceptance of HF operations and requires a detailed knowledge about the fracture formation. We jointly analyze two very different data sets recorded during mine-scale HF experiments: (a) the tilting of the ground caused by the opening of the fractures, as recorded by broadband seismometers-usually deployed for earthquake monitoring-installed close to the experiments and (b) a catalog of acoustic emissions, seismic signals of few milliseconds emitted by tiny cracks around the forming hydraulic fracture. The novel joint analysis allows to characterize the fracturing processes in greater detail, contributing to the understanding of the physical processes, which may help to understand fluid-injection-induced seismicity and validate the formation of hydraulic fractures.
KW  - hydraulic fracturing
KW  - fracture growth
KW  - tilt
KW  - acoustic emissions
KW  - injections
KW  - broadband seismometer
Y1  - 2021
U6  - https://doi.org/10.1029/2021JB023057
SN  - 2169-9313
SN  - 2169-9356
VL  - 126
IS  - 12
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Wang, Lei
A1  - Rybacki, Erik
A1  - Bonnelye, Audrey
A1  - Bohnhoff, Marco
A1  - Dresen, Georg
T1  - Experimental investigation on static and dynamic bulk moduli of dry and fluid-saturated porous sandstones
JF  - Rock mechanics and rock engineering
N2  - Knowledge of pressure-dependent static and dynamic moduli of porous reservoir rocks is of key importance for evaluating geological setting of a reservoir in geo-energy applications. We examined experimentally the evolution of static and dynamic bulk moduli for porous Bentheim sandstone with increasing confining pressure up to about 190 MPa under dry and water-saturated conditions. The static bulk moduli (K-s) were estimated from stress-volumetric strain curves while dynamic bulk moduli (K-d) were derived from the changes in ultrasonic P- and S- wave velocities (similar to 1 MHz) along different traces, which were monitored simultaneously during the entire deformation. In conjunction with published data of other porous sandstones (Berea, Navajo and Weber sandstones), our results reveal that the ratio between dynamic and static bulk moduli (K-d/K-s) reduces rapidly from about 1.5 - 2.0 at ambient pressure to about 1.1 at high pressure under dry conditions and from about 2.0 - 4.0 to about 1.5 under water-saturated conditions, respectively. We interpret such a pressure-dependent reduction by closure of narrow (compliant) cracks, highlighting thatK(d)/K(s)is positively correlated with the amount of narrow cracks. Above the crack closure pressure, where equant (stiff) pores dominate the void space,K-d/K(s)is almost constant. The enhanced difference between dynamic and static bulk moduli under water saturation compared to dry conditions is possibly caused by high pore pressure that is locally maintained if measured using high-frequency ultrasonic wave velocities. In our experiments, the pressure dependence of dynamic bulk modulus of water-saturated Bentheim sandstone at effective pressures above 5 MPa can be roughly predicted by both the effective medium theory (Mori-Tanaka scheme) and the squirt-flow model. Static bulk moduli are found to be more sensitive to narrow cracks than dynamic bulk moduli for porous sandstones under dry and water-saturated conditions.
KW  - Porous sandstone
KW  - Static bulk modulus
KW  - Dynamic bulk modulus
KW  - Narrow
KW  - (compliant) cracks
KW  - Equant (stiff) pores
Y1  - 2020
U6  - https://doi.org/10.1007/s00603-020-02248-3
SN  - 0723-2632
SN  - 1434-453X
VL  - 54
IS  - 1
SP  - 129
EP  - 148
PB  - Springer
CY  - Wien
ER  - 
TY  - JOUR
A1  - Riller, Ulrich
A1  - Giambiagi, Laura
A1  - Strecker, Manfred
T1  - From proterozoic tectonics to quaternary climate variability
BT  - earth system science studies in Latin America
JF  - International journal of earth sciences
Y1  - 2021
U6  - https://doi.org/10.1007/s00531-021-02095-9
SN  - 1437-3254
SN  - 1437-3262
VL  - 110
IS  - 7
SP  - 2269
EP  - 2271
PB  - Springer
CY  - Berlin ; Heidelberg
ER  - 
TY  - JOUR
A1  - Wetzel, Maria
A1  - Kempka, Thomas
A1  - Kühn, Michael
T1  - Diagenetic trends of synthetic reservoir sandstone properties assessed by digital rock physics
JF  - Minerals
N2  - Quantifying interactions and dependencies among geometric, hydraulic and mechanical properties of reservoir sandstones is of particular importance for the exploration and utilisation of the geological subsurface and can be assessed by synthetic sandstones comprising the microstructural complexity of natural rocks. In the present study, three highly resolved samples of the Fontainebleau, Berea and Bentheim sandstones are generated by means of a process-based approach, which combines the gravity-driven deposition of irregularly shaped grains and their diagenetic cementation by three different schemes. The resulting evolution in porosity, permeability and rock stiffness is examined and compared to the respective micro-computer tomographic (micro-CT) scans. The grain contact-preferential scheme implies a progressive clogging of small throats and consequently produces considerably less connected and stiffer samples than the two other schemes. By contrast, uniform quartz overgrowth continuously alters the pore space and leads to the lowest elastic properties. The proposed stress-dependent cementation scheme combines both approaches of contact-cement and quartz overgrowth, resulting in granulometric, hydraulic and elastic properties equivalent to those of the respective micro-CT scans, where bulk moduli slightly deviate by 0.8%, 4.9% and 2.5% for the Fontainebleau, Berea and Bentheim sandstone, respectively. The synthetic samples can be further altered to examine the impact of mineral dissolution or precipitation as well as fracturing on various petrophysical correlations, which is of particular relevance for numerous aspects of a sustainable subsurface utilisation.
KW  - digital core reconstruction
KW  - micro-CT scan
KW  - pore-scale
KW  - cementation
KW  - permeability-porosity relationship
KW  - elastic rock properties
KW  - numerical
KW  - simulation
Y1  - 2021
U6  - https://doi.org/10.3390/min11020151
SN  - 2075-163X
VL  - 11
IS  - 2
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Heckenbach, Esther Lina
A1  - Brune, Sascha
A1  - Glerum, Anne C.
A1  - Bott, Judith
T1  - Is there a speed limit for the thermal steady-state assumption in continental rifts?
JF  - Geochemistry, geophysics, geosystems : G 3 ; an electronic journal of the earth sciences
N2  - The lithosphere is often assumed to reside in a thermal steady-state when quantitatively describing the temperature distribution in continental interiors and sedimentary basins, but also at active plate boundaries. Here, we investigate the applicability limit of this assumption at slowly deforming continental rifts. To this aim, we assess the tectonic thermal imprint in numerical experiments that cover a range of realistic rift configurations. For each model scenario, the deviation from thermal equilibrium is evaluated. This is done by comparing the transient temperature field of every model to a corresponding steady-state model with an identical structural configuration. We find that the validity of the thermal steady-state assumption strongly depends on rift type, divergence velocity, sampling location, and depth within the rift. Maximum differences between transient and steady-state models occur in narrow rifts, at the rift sides, and if the extension rate exceeds 0.5-2 mm/a. Wide rifts, however, reside close to thermal steady-state even for high extension velocities. The transient imprint of rifting appears to be overall negligible for shallow isotherms with a temperature less than 100 degrees C. Contrarily, a steady-state treatment of deep crustal isotherms leads to an underestimation of crustal temperatures, especially for narrow rift settings. Thus, not only relatively fast rifts like the Gulf of Corinth, Red Sea, and Main Ethiopian Rift, but even slow rifts like the Kenya Rift, Rhine Graben, and Rio Grande Rift must be expected to feature a pronounced transient component in the temperature field and to therefore violate the thermal steady-state assumption for deeper crustal isotherms.
KW  - basin analysis
KW  - geodynamics
KW  - numerical modeling
KW  - rifting
KW  - thermal
KW  - modeling
Y1  - 2021
U6  - https://doi.org/10.1029/2020GC009577
SN  - 1525-2027
VL  - 22
IS  - 3
PB  - Wiley
CY  - Hoboken, NJ
ER  - 
TY  - JOUR
A1  - Bastian, Philipp U.
A1  - Robel, Nathalie
A1  - Schmidt, Peter
A1  - Schrumpf, Tim
A1  - Günter, Christina
A1  - Roddatis, Vladimir
A1  - Kumke, Michael U.
T1  - Resonance energy transfer to track the motion of lanthanide ions
BT  - what drives the intermixing in core-shell upconverting nanoparticles?
JF  - Biosensors : open access journal
N2  - The imagination of clearly separated core-shell structures is already outdated by the fact, that the nanoparticle core-shell structures remain in terms of efficiency behind their respective bulk material due to intermixing between core and shell dopant ions. In order to optimize the photoluminescence of core-shell UCNP the intermixing should be as small as possible and therefore, key parameters of this process need to be identified. In the present work the Ln(III) ion migration in the host lattices NaYF4 and NaGdF4 was monitored. These investigations have been performed by laser spectroscopy with help of lanthanide resonance energy transfer (LRET) between Eu(III) as donor and Pr(III) or Nd(III) as acceptor. The LRET is evaluated based on the Forster theory. The findings corroborate the literature and point out the migration of ions in the host lattices. Based on the introduced LRET model, the acceptor concentration in the surrounding of one donor depends clearly on the design of the applied core-shell-shell nanoparticles. In general, thinner intermediate insulating shells lead to higher acceptor concentration, stronger quenching of the Eu(III) donor and subsequently stronger sensitization of the Pr(III) or the Nd(III) acceptors. The choice of the host lattice as well as of the synthesis temperature are parameters to be considered for the intermixing process.
KW  - upconversion nanoparticles
KW  - lanthanoid migration
KW  - lanthanides
KW  - core-shell
KW  - energy transfer
Y1  - 2021
U6  - https://doi.org/10.3390/bios11120515
SN  - 2079-6374
VL  - 11
IS  - 12
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - De Lucia, Marco
A1  - Kühn, Michael
T1  - DecTree v1.0-chemistry speedup in reactive transport simulations
BT  - purely data-driven and physics-based surrogates
JF  - Geoscientific model development : an interactive open access journal of the European Geosciences Union
N2  - The computational costs associated with coupled reactive transport simulations are mostly due to the chemical subsystem: replacing it with a pre-trained statistical surrogate is a promising strategy to achieve decisive speedups at the price of small accuracy losses and thus to extend the scale of problems which can be handled. We introduce a hierarchical coupling scheme in which "full-physics" equation-based geochemical simulations are partially replaced by surrogates. Errors in mass balance resulting from multivariate surrogate predictions effectively assess the accuracy of multivariate regressions at runtime: inaccurate surrogate predictions are rejected and the more expensive equation-based simulations are run instead. Gradient boosting regressors such as XGBoost, not requiring data standardization and being able to handle Tweedie distributions, proved to be a suitable emulator. Finally, we devise a surrogate approach based on geochemical knowledge, which overcomes the issue of robustness when encountering previously unseen data and which can serve as a basis for further development of hybrid physics-AI modelling.
Y1  - 2021
U6  - https://doi.org/10.5194/gmd-14-4713-2021
SN  - 1991-959X
SN  - 1991-9603
VL  - 14
IS  - 7
SP  - 4713
EP  - 4730
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Cheng, Chaojie
A1  - Milsch, Harald
T1  - Hydromechanical investigations on the self-propping potential of fractures in tight sandstones
JF  - Rock mechanics and rock engineering
N2  - The hydromechanical properties of single self-propping fractures under stress are of fundamental interest for fractured-rock hydrology and a large number of geotechnical applications. This experimental study investigates fracture closure and hydraulic aperture changes of displaced tensile fractures, aligned tensile fractures, and saw-cut fractures for two types of sandstone (i.e., Flechtinger and Fontainebleau) with contrasting mechanical properties, cycling confining pressure between 5 and 30 MPa. Emphasis is placed on how surface roughness, fracture wall offset, and the mechanical properties of the contact asperities affect the self-propping potential of these fractures under normal stress. A relative fracture wall displacement can significantly increase fracture aperture and hydraulic conductivity, but the degree of increase strongly depends on the fracture surface roughness. For smooth fractures, surface roughness remains scale-independent as long as the fracture area is larger than a roll-off wavelength and thus any further displacement does not affect fracture aperture. For rough tensile fractures, these are self-affine over a larger scale so that an incremental fracture wall offset likely leads to an increase in fracture aperture. X-ray microtomography of the fractures indicates that the contact area ratio of the tensile fractures after the confining pressure cycle inversely correlates with the fracture wall offset yielding values in the range of about 3-25%, depending, first, on the respective surface roughness and, second, on the strength of the asperities in contact. Moreover, the contact asperities mainly occur isolated and tend to be preferentially oriented in the direction perpendicular to the fracture wall displacement which, in turn, may induce flow anisotropy. This, overall, implies that relatively harder sedimentary rocks have a higher self-propping potential for sustainable fluid flow through fractures in comparison to relatively soft rocks when specific conditions regarding surface roughness and fracture wall offset are met.
KW  - Self-propping fracture
KW  - Mechanical aperture
KW  - Hydraulic aperture
KW  - Normal
KW  - stress
KW  - Fracture wall offset
KW  - Surface roughness
Y1  - 2021
U6  - https://doi.org/10.1007/s00603-021-02500-4
SN  - 0723-2632
SN  - 1434-453X
VL  - 54
IS  - 10
SP  - 5407
EP  - 5432
PB  - Springer
CY  - Wien
ER  - 
TY  - JOUR
A1  - Pan, Mengdi
A1  - Schicks, Judith M.
T1  - Influence of gas supply changes on the formation process of complex mixed gas hydrates
JF  - Molecules : a journal of synthetic chemistry and natural product chemistry / Molecular Diversity Preservation International
N2  - Natural gas hydrate occurrences contain predominantly methane; however, there are increasing reports of complex mixed gas hydrates and coexisting hydrate phases. Changes in the feed gas composition due to the preferred incorporation of certain components into the hydrate phase and an inadequate gas supply is often assumed to be the cause of coexisting hydrate phases. This could also be the case for the gas hydrate system in Qilian Mountain permafrost (QMP), which is mainly controlled by pores and fractures with complex gas compositions. This study is dedicated to the experimental investigations on the formation process of mixed gas hydrates based on the reservoir conditions in QMP. Hydrates were synthesized from water and a gas mixture under different gas supply conditions to study the effects on the hydrate formation process. In situ Raman spectroscopic measurements and microscopic observations were applied to record changes in both gas and hydrate phase over the whole formation process. The results demonstrated the effects of gas flow on the composition of the resulting hydrate phase, indicating a competitive enclathration of guest molecules into the hydrate lattice depending on their properties. Another observation was that despite significant changes in the gas composition, no coexisting hydrate phases were formed.
KW  - mixed gas hydrates
KW  - hydrate formation process
KW  - coexisting phases
KW  - in
KW  - situ Raman spectroscopy
KW  - gas supply conditions
Y1  - 2021
U6  - https://doi.org/10.3390/molecules26103039
SN  - 1420-3049
VL  - 26
IS  - 10
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Saki, Adel
A1  - Miri, Mirmohammad
A1  - Oberhänsli, Roland
T1  - Pseudosection modelling of the Precambrian meta-pelites from the Poshtuk area, NW Iran
JF  - Periodico di mineralogia : an international journal of mineralogy, crystallography, geochemistry, ore deposits, petrology, volcanology and applied topics on environment, archaeometry and cultural heritage / Dipartimento di Scienze della Terra, Università degli Studi di Roma la Sapienza
N2  - Precambrian meta-pelites of the Poshtuk area in northwest Iran contain the prograde mineral assemblage staurolite-garnet-chloritoid-muscovite-biotite that was replaced by the assemblage garnet-staurolite-chlorite-muscovite-biotite at peak metamorphic condition. 
Whole-rock compositions reveal that high Fe, Al and Mn contents of their protolith rendered them prone to form these assemblages. Pseudosections calculated in KFMASH, MnKFMASH, and MnNCKFMASHO systems were used to investigate the P-T evolution of the samples. They clearly show the significant effect of MnO on the stability of the chloritoid-bearing assemblages and the formation of garnet through consumption of chlorite and chloritoid. The pseudosection in a T- aH(2)O diagram shows that the studied assemblage could be stable only at a(H2O)>0.8. X-Mg isopleths for garnet and biotite point to peak P-T conditions of about 3.75 kbar and 575 degrees C. Chloritoid stability is overstepped with such conditions. This can be attributed to thermal perturbation due to plutonism. It is concluded, metamorphism was primarily controlled by advective heat from magmatic intrusions in the Poshtuk area. The Precambrian basement complexes were extensively overprinted by the Pan-African Orogeny as well as younger magmatic and metamorphic activities associated to Alpine Orogeny during convergence of Arabian and Eurasian plate.
KW  - meta-pelites
KW  - pseudosection
KW  - chloritoid stability
KW  - Precambrain
KW  - Poshtuk
Y1  - 2021
U6  - https://doi.org/10.13133/2239-1002/16632
SN  - 0369-8963
VL  - 90
IS  - 3
SP  - 325
EP  - 340
PB  - Bardi
CY  - Roma
ER  - 
TY  - JOUR
A1  - Blanchard, Ingrid
A1  - Abeykoon, Sumith
A1  - Frost, Daniel J.
A1  - Rubie, David C.
T1  - Sulfur content at sulfide saturation of peridotitic melt at upper mantle conditions
JF  - American mineralogist : an international journal of earth and planetary materials / Mineralogical Society of America
N2  - The concentration of sulfur that can be dissolved in a silicate liquid is of fundamental importance because it is closely associated with several major Earth-related processes. Considerable effort has been made to understand the interplay between the effects of silicate melt composition and its capac-ity to retain sulfur, but the dependence on pressure and temperature is mostly based on experiments performed at pressures and temperatures below 6 GPa and 2073 K. Here we present a study of the effects of pressure and temperature on sulfur content at sulfide saturation of a peridotitic liquid. We performed 14 multi-anvil experiments using a peridotitic starting composition, and we produced 25 new measurements at conditions ranging from 7 to 23 GPa and 2173 to 2623 K. We analyzed the recovered samples using both electron microprobe and laser ablation ICP-MS. We compiled our data together with previously published data that were obtained at lower P-T conditions and with various silicate melt compositions. We present a new model based on this combined data set that encompasses the entire range of upper mantle pressure-temperature conditions, along with the effect of a wide range of silicate melt compositions. Our findings are consistent with earlier work based on extrapolation from lower-pressure and lower-temperature experiments and show a decrease of sulfur content at sulfide saturation (SCSS) with increasing pressure and an increase of SCSS with increasing temperature. We have extrapolated our results to pressure-temperature conditions of the Earth's primitive magma ocean, and show that FeS will exsolve from the molten silicate and can effectively be extracted to the core by a process that has been termed the "Hadean Matte." We also discuss briefly the implications of our results for the lunar magma ocean.
KW  - Peridotitic melts
KW  - sulfur solubility
KW  - high pressure
KW  - high temperature
KW  - magma ocean
Y1  - 2021
U6  - https://doi.org/10.2138/am-2021-7649
SN  - 0003-004X
SN  - 1945-3027
VL  - 106
IS  - 11
SP  - 1835
EP  - 1843
PB  - Mineralogical Society of America
CY  - Washington, DC [u.a.]
ER  - 
TY  - JOUR
A1  - Savi, Sara
A1  - Comiti, Francesco
A1  - Strecker, Manfred
T1  - Pronounced increase in slope instability linked to global warming
BT  - a case study from the eastern European Alps
JF  - Earth surface processes and landforms : the journal of the British Geomorphological Research Group
N2  - In recent decades, slope instability in high-mountain regions has often been linked to increase in temperature and the associated permafrost degradation and/or the increase in frequency/intensity of rainstorm events. In this context we analyzed the spatiotemporal evolution and potential controlling mechanisms of small- to medium-sized mass movements in a high-elevation catchment of the Italian Alps (Sulden/Solda basin). We found that slope-failure events (mostly in the form of rockfalls) have increased since the 2000s, whereas the occurrence of debris flows has increased only since 2010. The current climate-warming trend registered in the study area apparently increases the elevation of rockfall-detachment areas by approximately 300 m, mostly controlled by the combined effects of frost-cracking and permafrost thawing. In contrast, the occurrence of debris flows does not exhibit such an altitudinal shift, as it is primarily driven by extreme precipitation events exceeding the 75th percentile of the intensity-duration rainfall distribution. Potential debris-flow events in this environment may additionally be influenced by the accumulation of unconsolidated debris over time, which is then released during extreme rainfall events. Overall, there is evidence that the upper Sulden/Solda basin (above ca. 2500 m above sea level [a.s.l.]), and especially the areas in the proximity of glaciers, have experienced a significant decrease in slope stability since the 2000s, and that an increase in rockfalls and debris flows during spring and summer can be inferred. Our study thus confirms that "forward-looking" hazard mapping should be undertaken in these increasingly frequented, high-elevation areas of the Alps, as environmental change has elevated the overall hazard level in these regions.
KW  - debris flows
KW  - frost‐ cracking
KW  - multi‐ temporal analyses
KW  - permafrost
KW  - rainfall events
KW  - rockfalls
KW  - temperature extremes
Y1  - 2021
U6  - https://doi.org/10.1002/esp.5100
SN  - 0197-9337
SN  - 1096-9837
VL  - 46
IS  - 7
SP  - 1328
EP  - 1347
PB  - Wiley
CY  - New York
ER  - 
TY  - JOUR
A1  - Eichhorn, Sebastian
A1  - Rusche, Karsten
A1  - Weith, Thomas
T1  - Integrative governance processes towards sustainable spatial development
BT  - solving conflicts between urban infill development and climate change adaptation
JF  - Journal of environmental planning and management
N2  - Due to the high concentration of people and infrastructures in European cities, the possible impacts of climate change are particularly high (cities' social, economic and technical vulnerabilities). Adaptation measures to reduce the sensitivity of a city to climate risks are therefore of particular importance. Nevertheless, it is also common to develop compact and dense urban areas to reduce urban sprawl. Urban infill development and sustainable spatial climate policies are thus in apparent conflict with each other. This article examines how German cities deal with the tensions between these two policy fields. Using six case studies, a new heuristic analysis method is applied. This study identifies three key governance aspects that are essential for promoting the joint implementation: instruments, organisation and interaction. Based on our case studies, we conclude that successful implementation can only be achieved through integrative governance including all three domains.
KW  - urban infill development
KW  - climate change adaptation
KW  - governance
KW  - social
KW  - innovation
KW  - heuristic analysis
Y1  - 2021
U6  - https://doi.org/10.1080/09640568.2020.1866509
SN  - 0964-0568
SN  - 1360-0559
VL  - 64
IS  - 12
SP  - 2233
EP  - 2256
PB  - Routledge, Taylor & Francis Group
CY  - Abingdon
ER  - 
TY  - JOUR
A1  - Koyan, Philipp
A1  - Tronicke, Jens
A1  - Allroggen, Niklas
T1  - 3D ground-penetrating radar attributes to generate classified facies models
BT  - a case study from a dune island
JF  - Geophysics
N2  - Ground-penetrating radar (GPR) is a standard geophysical technique used to image near-surface structures in sedimentary environments. In such environments, GPR data acquisition and processing are increasingly following 3D strategies. However, the processed GPR data volumes are typically still interpreted using selected 2D slices and manual concepts such as GPR facies analyses. In seismic volume interpretation, the application of (semi-)automated and reproducible approaches such as 3D attribute analyses as well as the production of attribute-based facies models are common practices today. In contrast, the field of 3D GPR attribute analyses and corresponding facies models is largely untapped. We have developed and applied a workflow to produce 3D attribute-based GPR facies models comprising the dominant sedimentary reflection patterns in a GPR volume, which images complex sandy structures on the dune island of Spiekeroog (Northern Germany). After presenting our field site and details regarding our data acquisition and processing, we calculate and filter 3D texture attributes to generate a database comprising the dominant texture features of our GPR data. Then, we perform a dimensionality reduction of this database to obtain meta texture attributes, which we analyze and integrate using composite imaging and (also considering additional geometric information) fuzzy c-means cluster analysis resulting in a classified GPR facies model. Considering our facies model and a corresponding GPR facies chart, we interpret our GPR data set in terms of near-surface sedimentary units, the corresponding depositional environments, and the recent formation history at our field site. Thus, we demonstrate the potential of our workflow, which represents a novel and clear strategy to perform a more objective and consistent interpretation of 3D GPR data collected across different sedimentary environments.
KW  - ground-penetrating radar
KW  - attributes
KW  - interpretation
KW  - sedimentology
Y1  - 2021
U6  - https://doi.org/10.1190/GEO2021-0204.1
SN  - 0016-8033
SN  - 1942-2156
VL  - 86
IS  - 6
SP  - B335
EP  - B347
PB  - Society of Exploration Geophysicists
CY  - Tulsa
ER  - 
TY  - JOUR
A1  - Steinberg, Andreas
A1  - Vasyura-Bathke, Hannes
A1  - Gaebler, Peter Jost
A1  - Ohrnberger, Matthias
A1  - Ceranna, Lars
T1  - Estimation of seismic moment tensors using variational inference machine learning
JF  - Journal of geophysical research : Solid earth
N2  - We present an approach for rapidly estimating full moment tensors of earthquakes and their parameter uncertainties based on short time windows of recorded seismic waveform data by considering deep learning of Bayesian Neural Networks (BNNs). The individual neural networks are trained on synthetic seismic waveform data and corresponding known earthquake moment-tensor parameters. A monitoring volume has been predefined to form a three-dimensional grid of locations and to train a BNN for each grid point. Variational inference on several of these networks allows us to consider several sources of error and how they affect the estimated full moment-tensor parameters and their uncertainties. In particular, we demonstrate how estimated parameter distributions are affected by uncertainties in the earthquake centroid location in space and time as well as in the assumed Earth structure model. We apply our approach as a proof of concept on seismic waveform recordings of aftershocks of the Ridgecrest 2019 earthquake with moment magnitudes ranging from Mw 2.7 to Mw 5.5. Overall, good agreement has been achieved between inferred parameter ensembles and independently estimated parameters using classical methods. Our developed approach is fast and robust, and therefore, suitable for down-stream analyses that need rapid estimates of the source mechanism for a large number of earthquakes.
KW  - seismology
KW  - machine learning
KW  - earthquake source
KW  - moment tensor
KW  - full
KW  - waveform
Y1  - 2021
U6  - https://doi.org/10.1029/2021JB022685
SN  - 2169-9313
SN  - 2169-9356
VL  - 126
IS  - 10
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Smith, Taylor
A1  - Rheinwalt, Aljoscha
A1  - Bookhagen, Bodo
T1  - Topography and climate in the upper Indus Basin
BT  - Mapping elevation-snow cover relationships
JF  - The science of the total environment : an international journal for scientific research into the environment and its relationship with man
N2  - The Upper Indus Basin (UIB), which covers a wide range of climatic and topographic settings, provides an ideal venue to explore the relationship between climate and topography. While the distribution of snow and glaciers is spatially and temporally heterogeneous, there exist regions with similar elevation-snow relationships. In this work, we construct elevation-binned snow-cover statistics to analyze 3415 watersheds and 7357 glaciers in the UIB region. We group both glaciers and watersheds using a hierarchical clustering approach and find that (1) watershed clusters mirror large-scale moisture transport patterns and (2) are highly dependent on median watershed elevation. (3) Glacier clusters are spatially heterogeneous and are less strongly controlled by elevation, but rather by local topographic parameters that modify solar insolation. Our clustering approach allows us to clearly define self-similar snow-topographic regions. Eastern watersheds in the UIB show a steep snow cover-elevation relationship whereas watersheds in the central and western UIB have moderately sloped relationships, but cluster in distinct groups. We highlight this snow-cover-topographic transition zone and argue that these watersheds have different hydrologic responses than other regions. Our hierarchical clustering approach provides a potential new framework to use in defining climatic zones in the cyrosphere based on empirical data.
KW  - Snow-cover
KW  - Hierarchical clustering
KW  - Glaciers
KW  - Upper Indus Basin
Y1  - 2021
U6  - https://doi.org/10.1016/j.scitotenv.2021.147363
SN  - 0048-9697
SN  - 1879-1026
VL  - 786
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Smith, Taylor
A1  - Bookhagen, Bodo
T1  - Climatic and biotic controls on topographic asymmetry at the global scale
JF  - Journal of geophysical research : JGR, Earth surface
N2  - Insolation differences play a primary role in controlling microclimate and vegetation cover, which together influence the development of topography. Topographic asymmetry (TA), or slope differences between terrain aspects, has been well documented in small-scale, field-based, and modeling studies. Here we combine a suite of environmental (e.g., vegetation, temperature, solar insolation) and topographic (e.g., elevation, drainage network) data to explore the driving mechanisms and markers of TA on a global scale. Using a novel empirical TA analysis method, we find that (1) steeper terrain has higher TA magnitudes, (2) globally, pole-facing terrain is on average steeper than equator-facing terrain, especially in mid-latitude, tectonically quiescent, and vegetated landscapes, and (3) high-elevation and low-temperature regions tend to have terrain steepened toward the equator. We further show that there are distinct differences in climate and vegetation cover across terrain aspects, and that TA is reflected in the size and form of fluvial drainage networks. Our work supports the argument that insolation asymmetries engender differences in local microclimates and vegetation on opposing terrain aspects, which broadly encourage the development of asymmetric topography across a range of lithologic, tectonic, geomorphic, and climatic settings.
KW  - erosion
KW  - freeze-thaw cycling
KW  - solar radiation
KW  - topographic asymmetry
KW  - topography
KW  - vegetation cover
Y1  - 2021
U6  - https://doi.org/10.1029/2020JF005692
SN  - 2169-9003
SN  - 2169-9011
VL  - 126
IS  - 1
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Terbishalieva, Baiansuluu
A1  - Timmerman, Martin Jan
A1  - Mikolaichuk, Alexander
A1  - Altenberger, Uwe
A1  - Slama, Jiri
A1  - Schleicher, Anja Maria
A1  - Sudo, Masafumi
A1  - Sobel, Edward
A1  - Cichy, Sarah Bettina
T1  - Calc-alkaline volcanic rocks and zircon ages of the late Tonian
BT  - Early Cryogenian arc-related Big Naryn Complex in the Eastern Djetim-Too Range, Middle Tianshan block, Kyrgyzstan
JF  - International journal of earth sciences
N2  - The Big Naryn Complex (BNC) in the East Djetim-Too Range of the Kyrgyz Middle Tianshan block is a tectonized, at least 2 km thick sequence of predominantly felsic to intermediate volcanic rocks intruded by porphyric rhyolite sills. It overlies a basement of metamorphic rocks and is overlain by late Neoproterozoic Djetim-Too Formation sediments; these also occur as tectonic intercalations in the BNC. The up to ca. 1100 m thick Lower Member is composed of predominantly rhyolites-to-dacites and minor basalts, while the at least 900 m thick pyroclastic Upper Member is dominated by rhyolitic-to-dacitic ignimbrites. Porphyric rhyolite sills are concentrated at the top of the Lower Member. A Lower Member rhyolite and a sill sample have LA-ICP-MS U-Pb zircon crystallization ages of 726.1 +/- 2.2 Ma and 720.3 +/- 6.5 Ma, respectively, showing that most of the magmatism occurred within a short time span in the late Tonian-early Cryogenian. Inherited zircons in the sill sample have Neoarchean (2.63, 2.64 Ga), Paleo- (2.33-1.81 Ga), Meso- (1.55 Ga), and Neoproterozoic (ca. 815 Ma) ages, and were derived from a heterogeneous Kuilyu Complex basement. A 1751 +/- 7 Ma Ar-40/Ar-39 age for amphibole from metagabbro is the age of cooling subsequent to Paleoproterozoic metamorphism of the Kuilyu Complex. The large amount of pyroclastic rocks, and their major and trace element compositions, the presence of Neoarchean to Neoproterozoic inherited zircons and a depositional basement of metamorphic rocks point to formation of the BNC in a continental magmatic arc setting.
KW  - Tianshan orogenic belt
KW  - Big Naryn complex
KW  - Tonian–Cryogenian
KW  - magmatic arc
KW  - calc-alkaline
KW  - Kuilyu complex
Y1  - 2021
U6  - https://doi.org/10.1007/s00531-020-01956-z
SN  - 1437-3254
SN  - 1437-3262
VL  - 110
IS  - 1
SP  - 353
EP  - 375
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Dietze, Michael
A1  - Krautblatter, Michael
A1  - Illien, Luc
A1  - Hovius, Niels
T1  - Seismic constraints on rock damaging related to a failing mountain peak
BT  - The Hochvogel, Allgäu
JF  - Earth surface processes and landforms
N2  - Large rock slope failures play a pivotal role in long-term landscape evolution and are a major concern in land use planning and hazard aspects. While the failure phase and the time immediately prior to failure are increasingly well studied, the nature of the preparation phase remains enigmatic. This knowledge gap is due, to a large degree, to difficulties associated with instrumenting high mountain terrain and the local nature of classic monitoring methods, which does not allow integral observation of large rock volumes. Here, we analyse data from a small network of up to seven seismic sensors installed during July-October 2018 (with 43 days of data loss) at the summit of the Hochvogel, a 2592 m high Alpine peak. We develop proxy time series indicative of cyclic and progressive changes of the summit. Modal analysis, horizontal-to-vertical spectral ratio data and end-member modelling analysis reveal diurnal cycles of increasing and decreasing coupling stiffness of a 260,000 m(3) large, instable rock volume, due to thermal forcing. Relative seismic wave velocity changes also indicate diurnal accumulation and release of stress within the rock mass. At longer time scales, there is a systematic superimposed pattern of stress increased over multiple days and episodic stress release within a few days, expressed in an increased emission of short seismic pulses indicative of rock cracking. Our data provide essential first order information on the development of large-scale slope instabilities towards catastrophic failure. (c) 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd
KW  - environmental seismology
KW  - fatigue
KW  - fundamental frequency
KW  - HVSR
KW  - mass
KW  - wasting
KW  - mountain geomorphology
KW  - natural hazard
KW  - noise cross
KW  - correlation
KW  - seismic monitoring
KW  - slope failure
Y1  - 2021
U6  - https://doi.org/10.1002/esp.5034
SN  - 0197-9337
SN  - 1096-9837
VL  - 46
IS  - 2
SP  - 417
EP  - 429
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Müting, Friederike Ariane
A1  - Bookhagen, Bodo
A1  - Strecker, Manfred
T1  - Identification of debris-flow channels using high-resolution topographic data
BT  - a case study in the Quebrada del Toro, NW Argentina
JF  - Journal of geophysical research : JGR, Earth surface
N2  - Resolving Earth's surface at the meter scale is essential for an improved understanding of the dynamics of mass-movement processes. In this study, we explore the applicability and potential of digital elevation models (DEMs) derived from stereophotogrammetry to detect debris-flow channels in the Quebrada del Toro in the northwestern Argentine Andes. Our analysis relies on a high-resolution (3 m) DEM created from SPOT-7 tri-stereo satellite data. We carefully validated DEM quality with ∼6,000 differential GPS points and identified optimal parameters for DEM generation in high-relief terrain. After multiple processing steps, we achieved an accuracy of 0.051 ± 1.915 m (1σ) using n = 3,139 control points with cm precision. Previous studies have used the drainage area and slope framework to identify topographic signatures of debris flows within a catchment. We built upon this and investigated individual river-channel segments using connected-component (CC) analysis on meter-scale topographic data. We define CC as segments of similar slope along the channel profile. Based on seven manually identified debris-flow catchments, we developed a debris-flow similarity index using component length and mean channel-segment slope and identified channel segments that have likely been shaped by debris flows. The presented approach has the potential to resolve intra-catchment variability of transport processes, allows to constrain the extent of debris-flow channels more precisely than slope-area analysis, and highlights the versatility of combined space- and field-based observations for natural-hazard assessments.
Y1  - 2021
U6  - https://doi.org/10.1029/2021JF006330
SN  - 2169-9003
SN  - 2169-9011
VL  - 126
IS  - 12
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Trauth, Martin H.
T1  - Spectral analysis in quaternary sciences
JF  - Quaternary science reviews : the international multidisciplinary research and review journal
N2  - Spectral analysis is a technique of time-series analysis that decomposes signals into linear combinations of harmonic components. Rooted in the 19th century, spectral analysis gained popularity in palaeoclimatology since the early 1980s. This was partly due to the availability of long time series of past climates, but also the development of new, partly adapted methods and the increasing spread of affordable personal computers. This paper reviews the most important methods of spectral analysis for palaeoclimate time series and discusses the prerequisites for their application as well as advantages and disadvantages. The paper also offers an overview of suitable software, as well as computer code for using the methods on synthetic examples.
KW  - Spectral analysis
KW  - Paleoclimate
KW  - Orbital forcing
KW  - MATLAB
Y1  - 2021
U6  - https://doi.org/10.1016/j.quascirev.2021.107157
SN  - 0277-3791
SN  - 1873-457X
VL  - 270
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Borchardt, Sven
A1  - Trauth, Martin H.
T1  - Erratum to: Borchardt, Sven, Trauth, Martin H.: Remotely-sensed evapotranspiration estimates for an improved hydrological modeling of the early Holocene mega-lake Suguta, northern Kenya Rift. - (Palaeogeography, Palaeoclimatology, Palaeoecology. - Volumes 361–362 (2012), S. 14 – 20. - doi.org/10.1016/j.palaeo.2012.07.009)
JF  - Palaeogeography, palaeoclimatology, palaeoecology : an international journal for the geo-sciences
Y1  - 2021
U6  - https://doi.org/10.1016/j.palaeo.2019.109540
SN  - 0031-0182
SN  - 1872-616X
VL  - 571
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Müller, Daniela
A1  - Tjallingii, Rik
A1  - Plociennik, Mateusz
A1  - Luoto, Tomi P.
A1  - Kotrys, Bartosz
A1  - Plessen, Birgit
A1  - Ramisch, Arne
A1  - Schwab, Markus Julius
A1  - Blaszkiewicz, Miroslaw
A1  - Slowinski, Michal
A1  - Brauer, Achim
T1  - New insights into lake responses to rapid climate change
BT  - The Younger Dryas in Lake Goscia(z) over dot, central Poland
JF  - Boreas
N2  - The sediment profile from Lake Goscia(z) over dot in central Poland comprises a continuous, seasonally resolved and exceptionally well-preserved archive of the Younger Dryas (YD) climate variation. This provides a unique opportunity for detailed investigation of lake system responses during periods of rapid climate cooling (YD onset) and warming (YD termination). The new varve record of Lake Goscia(z) over dot presented here spans 1662 years from the late Allerod (AL) to the early Preboreal (PB). Microscopic varve counting provides an independent chronology with a YD duration of 1149+14/-22 years, which confirms previous results of 1140 +/- 40 years. We link stable oxygen isotopes and chironomid-based air temperature reconstructions with the response of various geochemical and varve microfacies proxies especially focusing on the onset and termination of the YD. Cooling at the YD onset lasted similar to 180 years, which is about a century longer than the terminal warming that was completed in similar to 70 years. During the AL/YD transition, environmental proxy data lagged the onset of cooling by similar to 90 years and revealed an increase of lake productivity and internal lake re-suspension as well as slightly higher detrital sediment input. In contrast, rapid warming and environmental changes during the YD/PB transition occurred simultaneously. However, initial changes such as declining diatom deposition and detrital input occurred already a few centuries before the rapid warming at the YD/PB transition. These environmental changes likely reflect a gradual increase in summer air temperatures already during the YD. Our data indicate complex and differing environmental responses to the major climate changes related to the YD, which involve different proxy sensitivities and threshold processes.
KW  - central Poland
KW  - Younger Dryas
KW  - sedimentation pattern
KW  - lake sediments
Y1  - 2021
U6  - https://doi.org/10.23689/fidgeo-4033
SN  - 0300-9483
SN  - 1502-3885
VL  - 50
IS  - 2
SP  - 535
EP  - 555
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Purinton, Benjamin
A1  - Bookhagen, Bodo
T1  - Tracking downstream variability in large grain-size distributions in the South-Central Andes
JF  - Journal of geophysical research : F, Earth surface
N2  - Mixed sand- and gravel-bed rivers record erosion, transport, and fining signals in their bedload size distributions. Thus, grain-size data are imperative for studying these processes. However, collecting hundreds to thousands of pebble measurements in steep and dynamic high-mountain river settings remains challenging. Using the recently published digital grain-sizing algorithm PebbleCounts, we were able to survey seven large (>= 1,000 m2) channel cross-sections and measure thousands to tens-of-thousands of grains per survey along a 100-km stretch of the trunk stream of the Toro Basin in Northwest Argentina. The study region traverses a steep topographic and environmental gradient on the eastern margin of the Central Andean Plateau. Careful counting and validation allows us to identify measurement errors and constrain percentile uncertainties using large sample sizes. In the coarse >= 2.5 cm fraction of bedload, only the uppermost size percentiles (>= 95th) vary significantly downstream, whereas the 50th and 84th percentiles show less variability. We note a relation between increases in these upper percentiles and along-channel junctions with large, steep tributaries. This signal is strongly influenced by lithology and geologic structures, and mixed with local hillslope input. In steep catchments like the Toro Basin, we suggest nonlinear relationships between geomorphic metrics and grain size, whereby the steepest parts of the landscape exert primary control on the upper grain-size percentiles. Thus, average or median metrics that do not apply weights or thresholds to steeper topography may be less predictive of grain-size distributions in such settings.
KW  - digital grain sizing
KW  - downstream fining
KW  - fluvial geomorphology
KW  - grain-size distribution
KW  - pebblecounts
Y1  - 2021
U6  - https://doi.org/10.1029/2021JF006260
SN  - 2169-9003
SN  - 2169-9011
VL  - 126
IS  - 8
SP  - 1
EP  - 29
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - van der Beek, Peter
T1  - Stressed rocks cause big landslides
JF  - Nature geoscience
N2  - Near-surface stress patterns, influenced by topography, control the size and location of the largest landslides - but not necessarily smaller ones - according to a study of mountains at the eastern edge of the Tibetan Plateau.
KW  - relief
Y1  - 2021
U6  - https://doi.org/10.1038/s41561-021-00748-7
SN  - 1752-0894
SN  - 1752-0908
VL  - 14
IS  - 5
SP  - 261
EP  - 262
PB  - Nature Publishing Group
CY  - London
ER  - 
TY  - JOUR
A1  - Klein, Konstantin P.
A1  - Lantuit, Hugues
A1  - Heim, Birgit
A1  - Doxaran, David
A1  - Juhls, Bennet
A1  - Nitze, Ingmar
A1  - Walch, Daniela
A1  - Poste, Amanda
A1  - Søreide, Janne E.
T1  - The Arctic Nearshore Turbidity Algorithm (ANTA)
BT  - A multi sensor turbidity algorithm for Arctic nearshore environments
JF  - Science of remote sensing
N2  - The Arctic is greatly impacted by climate change. The increase in air temperature drives the thawing of permafrost and an increase in coastal erosion and river discharge. This leads to a greater input of sediment and organic matter into coastal waters, which substantially impacts the ecosystems by reducing light transmission through the water column and altering the biogeochemistry, but also the subsistence economy of local people, and changes in climate because of the transformation of organic matter into greenhouse gases. Yet, the quantification of suspended sediment in Arctic coastal and nearshore waters remains unsatisfactory due to the absence of dedicated algorithms to resolve the high loads occurring in the close vicinity of the shoreline. In this study we present the Arctic Nearshore Turbidity Algorithm (ANTA), the first reflectance-turbidity relationship specifically targeted towards Arctic nearshore waters that is tuned with in-situ measurements from the nearshore waters of Herschel Island Qikiqtaruk in the western Canadian Arctic. A semi-empirical model was calibrated for several relevant sensors in ocean color remote sensing, including MODIS, Sentinel 3 (OLCI), Landsat 8 (OLI), and Sentinel 2 (MSI), as well as the older Landsat sensors TM and ETM+. The ANTA performed better with Landsat 8 than with Sentinel 2 and Sentinel 3. The application of the ANTA to Sentinel 2 imagery that matches in-situ turbidity samples taken in Adventfjorden, Svalbard, shows transferability to nearshore areas beyond Herschel Island Qikiqtaruk.
KW  - Ocean color remote sensing
KW  - Turbidity retrieval
KW  - Nearshore zone
KW  - Arctic Ocean
Y1  - 2021
U6  - https://doi.org/10.1016/j.srs.2021.100036
SN  - 2666-0172
VL  - 4
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Purinton, Benjamin
A1  - Bookhagen, Bodo
T1  - Beyond Vertical Point Accuracy
BT  - Assessing Inter-pixel Consistency in 30 m Global DEMs for the Arid Central Andes
JF  - Frontiers in Earth Science
N2  - Quantitative geomorphic research depends on accurate topographic data often collected via remote sensing. Lidar, and photogrammetric methods like structure-from-motion, provide the highest quality data for generating digital elevation models (DEMs). Unfortunately, these data are restricted to relatively small areas, and may be expensive or time-consuming to collect. Global and near-global DEMs with 1 arcsec (∼30 m) ground sampling from spaceborne radar and optical sensors offer an alternative gridded, continuous surface at the cost of resolution and accuracy. Accuracy is typically defined with respect to external datasets, often, but not always, in the form of point or profile measurements from sources like differential Global Navigation Satellite System (GNSS), spaceborne lidar (e.g., ICESat), and other geodetic measurements. Vertical point or profile accuracy metrics can miss the pixel-to-pixel variability (sometimes called DEM noise) that is unrelated to true topographic signal, but rather sensor-, orbital-, and/or processing-related artifacts. This is most concerning in selecting a DEM for geomorphic analysis, as this variability can affect derivatives of elevation (e.g., slope and curvature) and impact flow routing. We use (near) global DEMs at 1 arcsec resolution (SRTM, ASTER, ALOS, TanDEM-X, and the recently released Copernicus) and develop new internal accuracy metrics to assess inter-pixel variability without reference data. Our study area is in the arid, steep Central Andes, and is nearly vegetation-free, creating ideal conditions for remote sensing of the bare-earth surface. We use a novel hillshade-filtering approach to detrend long-wavelength topographic signals and accentuate short-wavelength variability. Fourier transformations of the spatial signal to the frequency domain allows us to quantify: 1) artifacts in the un-projected 1 arcsec DEMs at wavelengths greater than the Nyquist (twice the nominal resolution, so > 2 arcsec); and 2) the relative variance of adjacent pixels in DEMs resampled to 30-m resolution (UTM projected). We translate results into their impact on hillslope and channel slope calculations, and we highlight the quality of the five DEMs. We find that the Copernicus DEM, which is based on a carefully edited commercial version of the TanDEM-X, provides the highest quality landscape representation, and should become the preferred DEM for topographic analysis in areas without sufficient coverage of higher-quality local DEMs.
KW  - DEM noise
KW  - Fourier analysis
KW  - TanDEM-X
KW  - ASTER GDEM
KW  - Copernicus DEM
KW  - WorldDEM
KW  - SRTM
KW  - ALOS World 3D
Y1  - 2021
U6  - https://doi.org/10.3389/feart.2021.758606
SN  - 2296-6463
SP  - 1
EP  - 24
PB  - Frontiers Media
CY  - Lausanne, Schweiz
ER  - 
TY  - JOUR
A1  - Kaboth-Bahr, Stefanie
A1  - Bahr, André
A1  - Stepanek, Christian
A1  - Catunda, Maria Carolina Amorim
A1  - Karas, Cyrus
A1  - Ziegler, Martin
A1  - García-Gallardo, Ángela
A1  - Grunert, Patrick
T1  - Mediterranean heat injection to the North Atlantic delayed the intensification of Northern Hemisphere glaciations
JF  - Communications Earth & Environment
N2  - The intensification of Northern Hemisphere glaciations at the end of the Pliocene epoch marks one of the most substantial climatic shifts of the Cenozoic. Despite global cooling, sea surface temperatures in the high latitude North Atlantic Ocean rose between 2.9–2.7 million years ago. Here we present sedimentary geochemical proxy data from the Gulf of Cadiz to reconstruct the variability of Mediterranean Outflow Water, an important heat source to the North Atlantic. We find evidence for enhanced production of Mediterranean Outflow from the mid-Pliocene to the late Pliocene which we infer could have driven a sub-surface heat channel into the high-latitude North Atlantic. We then use Earth System Models to constrain the impact of enhanced Mediterranean Outflow production on the northward heat transport in the North Atlantic. In accord with the proxy data, the numerical model results support the formation of a sub-surface channel that pumped heat from the subtropics into the high latitude North Atlantic. We further suggest that this mechanism could have delayed ice sheet growth at the end of the Pliocene.
Y1  - 2021
U6  - https://doi.org/10.1038/s43247-021-00232-5
SN  - 2662-4435
SP  - 1
EP  - 9
PB  - Springer Nature
CY  - London
ER  - 
TY  - JOUR
A1  - Ramezani Ziarani, Maryam
A1  - Bookhagen, Bodo
A1  - Schmidt, Torsten
A1  - Wickert, Jens
A1  - de la Torre, Alejandro
A1  - Deng, Zhiguo
A1  - Calori, Andrea
T1  - A model for the relationship between rainfall, GNSS-derived integrated water vapour, and CAPE in the eastern central Andes
JF  - Remote Sensing
N2  - Atmospheric water vapour content is a key variable that controls the development of deep convective storms and rainfall extremes over the central Andes. Direct measurements of water vapour are challenging; however, recent developments in microwave processing allow the use of phase delays from L-band radar to measure the water vapour content throughout the atmosphere: Global Navigation Satellite System (GNSS)-based integrated water vapour (IWV) monitoring shows promising results to measure vertically integrated water vapour at high temporal resolutions. Previous works also identified convective available potential energy (CAPE) as a key climatic variable for the formation of deep convective storms and rainfall in the central Andes. Our analysis relies on GNSS data from the Argentine Continuous Satellite Monitoring Network, Red Argentina de Monitoreo Satelital Continuo (RAMSAC) network from 1999 to 2013. CAPE is derived from version 2.0 of the ECMWF’s (European Centre for Medium-Range Weather Forecasts) Re-Analysis (ERA-interim) and rainfall from the TRMM (Tropical Rainfall Measuring Mission) product. In this study, we first analyse the rainfall characteristics of two GNSS-IWV stations by comparing their complementary cumulative distribution function (CCDF). Second, we separately derive the relation between rainfall vs. CAPE and GNSS-IWV. Based on our distribution fitting analysis, we observe an exponential relation of rainfall to GNSS-IWV. In contrast, we report a power-law relationship between the daily mean value of rainfall and CAPE at the GNSS-IWV station locations in the eastern central Andes that is close to the theoretical relationship based on parcel theory. Third, we generate a joint regression model through a multivariable regression analysis using CAPE and GNSS-IWV to explain the contribution of both variables in the presence of each other to extreme rainfall during the austral summer season. We found that rainfall can be characterised with a higher statistical significance for higher rainfall quantiles, e.g., the 0.9 quantile based on goodness-of-fit criterion for quantile regression. We observed different contributions of CAPE and GNSS-IWV to rainfall for each station for the 0.9 quantile. Fourth, we identify the temporal relation between extreme rainfall (the 90th, 95th, and 99th percentiles) and both GNSS-IWV and CAPE at 6 h time steps. We observed an increase before the rainfall event and at the time of peak rainfall—both for GNSS-integrated water vapour and CAPE. We show higher values of CAPE and GNSS-IWV for higher rainfall percentiles (99th and 95th percentiles) compared to the 90th percentile at a 6-h temporal scale. Based on our correlation analyses and the dynamics of the time series, we show that both GNSS-IWV and CAPE had comparable magnitudes, and we argue to consider both climatic variables when investigating their effect on rainfall extremes.
KW  - Global Navigation Satellite System (GNSS)
KW  - GNSS-integrated water vapour
KW  - convective available potential energy (CAPE)
KW  - extreme rainfall
KW  - TRMM
Y1  - 2021
U6  - https://doi.org/10.3390/rs13183788
SN  - 2072-4292
VL  - 13
IS  - 18
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Izgi, Gizem
A1  - Eibl, Eva P. S.
A1  - Donner, Stefanie
A1  - Bernauer, Felix
T1  - Performance test of the rotational sensor blueSeis-3A in a huddle test in Fürstenfeldbruck
JF  - Sensors
N2  - Rotational motions play a key role in measuring seismic wavefield properties. Using newly developed portable rotational instruments, it is now possible to directly measure rotational motions in a broad frequency range. Here, we investigated the instrumental self-noise and data quality in a huddle test in Fürstenfeldbruck, Germany, in August 2019. We compare the data from six rotational and three translational sensors. We studied the recorded signals using correlation, coherence analysis, and probabilistic power spectral densities. We sorted the coherent noise into five groups with respect to the similarities in frequency content and shape of the signals. These coherent noises were most likely caused by electrical devices, the dehumidifier system in the building, humans, and natural sources such as wind. We calculated self-noise levels through probabilistic power spectral densities and by applying the Sleeman method, a three-sensor method. Our results from both methods indicate that self-noise levels are stable between 0.5 and 40 Hz. Furthermore, we recorded the 29 August 2019 ML 3.4 Dettingen earthquake. The calculated source directions are found to be realistic for all sensors in comparison to the real back azimuth. We conclude that the five tested blueSeis-3A rotational sensors, when compared with respect to coherent noise, self-noise, and source direction, provide reliable and consistent results. Hence, field experiments with single rotational sensors can be undertaken.
KW  - rotational seismology
KW  - huddle test
KW  - coherency
KW  - source direction
KW  - coherent noise
KW  - blueSeis-3A sensors
Y1  - 2021
U6  - https://doi.org/10.3390/s21093170
SN  - 1424-8220
VL  - 21
IS  - 9
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Samprogna Mohor, Guilherme
A1  - Thieken, Annegret
A1  - Korup, Oliver
T1  - Residential flood loss estimated from Bayesian multilevel models
JF  - Natural Hazards and Earth System Sciences
N2  - Models for the predictions of monetary losses from floods mainly blend data deemed to represent a single flood type and region. Moreover, these approaches largely ignore indicators of preparedness and how predictors may vary between regions and events, challenging the transferability of flood loss models. We use a flood loss database of 1812 German flood-affected households to explore how Bayesian multilevel models can estimate normalised flood damage stratified by event, region, or flood process type. Multilevel models acknowledge natural groups in the data and allow each group to learn from others. We obtain posterior estimates that differ between flood types, with credibly varying influences of water depth, contamination, duration, implementation of property-level precautionary measures, insurance, and previous flood experience; these influences overlap across most events or regions, however. We infer that the underlying damaging processes of distinct flood types deserve further attention. Each reported flood loss and affected region involved mixed flood types, likely explaining the uncertainty in the coefficients. Our results emphasise the need to consider flood types as an important step towards applying flood loss models elsewhere. We argue that failing to do so may unduly generalise the model and systematically bias loss estimations from empirical data.
KW  - damage
KW  - insurance
KW  - Germany
KW  - transferability
KW  - preparedness
KW  - recovery
Y1  - 2020
U6  - https://doi.org/10.5194/nhess-21-1599-2021
SN  - 2195-9269
VL  - 21
SP  - 1599
EP  - 1614
PB  - European Geophysical Society
CY  - Katlenburg-Lindau
ER  - 
TY  - JOUR
A1  - Kaboth-Bahr, Stefanie
A1  - Bahr, André
A1  - Zeeden, Christian
A1  - Yamoah, Kweku A.
A1  - Lone, Mahjoor Ahmad
A1  - Chuang, Chih-Kai
A1  - Löwemark, Ludvig
A1  - Wei, Kuo-Yen
T1  - A tale of shifting relations
BT  - East Asian summer and winter monsoon variability during the Holocene
JF  - Scientific Reports
N2  - Understanding the dynamics between the East Asian summer (EASM) and winter monsoon (EAWM) is needed to predict their variability under future global warming scenarios. Here, we investigate the relationship between EASM and EAWM as well as the mechanisms driving their variability during the last 10,000 years by stacking marine and terrestrial (non-speleothem) proxy records from the East Asian realm. This provides a regional and proxy independent signal for both monsoonal systems. The respective signal was subsequently analysed using a linear regression model. We find that the phase relationship between EASM and EAWM is not time-constant and significantly depends on orbital configuration changes. In addition, changes in the Atlantic Meridional Overturning circulation, Arctic sea-ice coverage, El Niño-Southern Oscillation and Sun Spot numbers contributed to millennial scale changes in the EASM and EAWM during the Holocene. We also argue that the bulk signal of monsoonal activity captured by the stacked non-speleothem proxy records supports the previously argued bias of speleothem climatic archives to moisture source changes and/or seasonality.
KW  - Environmental sciences
KW  - Ocean sciences
KW  - Solid Earth sciences
Y1  - 2020
U6  - https://doi.org/10.1038/s41598-021-85444-7
SN  - 2045-2322
VL  - 11
PB  - Macmillan Publishers Limited, part of Springer Nature
CY  - London
ER  -