@misc{CodecoWeisTrumbulletal.2021, author = {Code{\c{c}}o, Marta S. and Weis, Philipp and Trumbull, Robert B. and Van Hinsberg, Vincent and Pinto, Filipe and Lecumberri-Sanchez, Pilar and Schleicher, Anja M.}, title = {The imprint of hydrothermal fluids on trace-element contents in white mica and tourmaline from the Panasqueira W-Sn-Cu deposit, Portugal}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1342}, issn = {1866-8372}, doi = {10.25932/publishup-51940}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-519403}, pages = {481 -- 508}, year = {2021}, abstract = {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.}, language = {en} } @phdthesis{Skiba2024, author = {Skiba, Vanessa}, title = {Alpine speleothems as recorders of glacier evolution}, doi = {10.25932/publishup-65537}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-655379}, school = {Universit{\"a}t Potsdam}, pages = {xx, 238}, year = {2024}, abstract = {The European Alps are amongst the regions with highest glacier mass loss rates over the last decades. Under the threat of ongoing climate change, the ability to predict glacier mass balance changes for water and risk management purposes has become imperative. This raises an urgent need for reliable glacier models. The European Alps do not only host glaciers, but also numerous caves containing carbonate formations, called speleothems. Previous studies have shown that those speleothems also grew during times when the cave was covered by a warm-based glacier. In this thesis, I utilise speleothems from the European Alps as archives of local, environmental conditions related to mountain glacier evolution. Previous studies have shown that speleothem isotope data from the Alps can be strongly affected by in-cave processes. Therefore, part of this thesis focusses on developing an isotope evolution model, which successfully reproduces differences between contemporaneous growing speleothems. The model is used to propose correction approaches for prior calcite precipitation effects on speleothem oxygen isotopes (δ18O). Applications on speleothem records from caves outside of the Alps demonstrate that corrected δ18O agrees better with other records and climate model simulations. Existing speleothem growth histories and carbon isotope (δ13C) records from Alpine caves located at different elevations are used to infer soil vs. glacier cover and the thermal regime of the glacier over the last glacial cycle. The compatibility with glacier evolution models is statistically assessed. A general agreement between speleothem δ13C-derived information on soil vs. glacier presence and modelled glacier coverage is found. However, glacier retreat during Marine Isotope Stage (MIS) 3 seems to be underestimated by the model. Furthermore, speleothem data provides evidence of surface temperature above the freezing point which is, however, not fully reproduced by the simulations. History of glacier cover and their thermal regime is explored for the high-elevation cave system Melchsee-Frutt in the Swiss Alps. Based on new (MIS 9b - MIS 7b, MIS 2) and available speleothem δ13C (MIS 7a - 5d) data, warm-based glacier cover is inferred for MIS 8, 7d, 6, and 2. Also a short period of cold-based ice coverage is found for early MIS 6. In a detailed multi-proxy analysis (δ18O, δ13C, Mg/Ca and Sr/Ca), millennial-scale changes in the glacier-related source of the water infiltrating in the karst during MIS 8 and 7d are found and linked to Northern Hemisphere climate variability. While speleothem records from high-elevation cave sites in the Alps exhibit huge potential for glacier reconstruction, several limitations remain, which are discussed throughout this thesis. Ultimately, recommendations are given to further leverage subglacial speleothems as an archive of glacier dynamics.}, language = {en} } @article{ObermannSanchezPastorWuetal.2022, author = {Obermann, Anne and Sanchez-Pastor, Pilar and Wu, Sin-Mei and Wollin, Christopher and Baird, Alan F. and Isken, Marius Paul and Clinton, John and Goertz-Allmann, Bettina P. and Dahm, Torsten and W{\"u}stefeld, Andreas and Shi, Peidong and Lanza, Federica and Gyger, Lea and Wetter, Selina and Hjorleifsdottir, Vala and Langet, Nadege and Brynjarsson, Baldur and Jousset, Philippe and Wiemer, Stefan}, title = {Combined large-N seismic arrays and DAS fiber optic cables across the Hengill geothermal field, Iceland}, series = {Seismological research letters}, volume = {93}, journal = {Seismological research letters}, number = {5}, publisher = {Seismological Society of America}, address = {Boulder, Colo.}, issn = {0895-0695}, doi = {10.1785/0220220073}, pages = {2498 -- 2514}, year = {2022}, abstract = {From June to August 2021, we deployed a dense seismic nodal network across the Hengill geothermal area in southwest Iceland to image and characterize faults and high-temperature zones at high resolution. The nodal network comprised 498 geophone nodes spread across the northern Nesjavellir and southern Hverahlio geothermal fields and was complemented by an existing permanent and temporary backbone seismic network of a total of 44 short-period and broadband stations. In addition, we recorded distributed acoustic sensing data along two fiber optic telecommunication cables near the Nesjavellir geothermal power plant with commercial interrogators. During the time of deployment, a vibroseis survey took place around the Nesjavellir power plant. Here, we describe the network and the recorded datasets. Furthermore, we showsome initial results that indicate a high data quality and highlight the potential of the seismic records for various follow up studies, such as high-resolution event location to delineate faults and body- and surface-wave tomographies to image the subsurface velocity structure in great detail.}, language = {en} } @article{VyseHerzschuhPfalzetal.2021, author = {Vyse, Stuart A. and Herzschuh, Ulrike and Pfalz, Gregor and Pestryakova, Lyudmila A. and Diekmann, Bernhard and Nowaczyk, Norbert and Biskaborn, Boris K.}, title = {Sediment and carbon accumulation in a glacial lake in Chukotka (Arctic Siberia) during the Late Pleistocene and Holocene}, series = {Biogeosciences}, volume = {18}, journal = {Biogeosciences}, number = {16}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1726-4170}, doi = {10.5194/bg-18-4791-2021}, pages = {4791 -- 4816}, year = {2021}, abstract = {Lakes act as important sinks for inorganic and organic sediment components. However, investigations of sedimentary carbon budgets within glacial lakes are currently absent from Arctic Siberia. The aim of this paper is to provide the first reconstruction of accumulation rates, sediment and carbon budgets from a lacustrine sediment core from Lake Rauchuagytgyn, Chukotka (Arctic Siberia). We combined multiple sediment biogeochemical and sedimentological parameters from a radiocarbon-dated 6.5m sediment core with lake basin hydroacoustic data to derive sediment stratigraphy, sediment volumes and infill budgets. Our results distinguished three principal sediment and carbon accumulation regimes that could be identified across all measured environmental proxies including early Marine Isotope Stage 2 (MIS2) (ca. 29-23.4 ka cal BP), mid-MIS2-early MIS1 (ca. 23.4-11.69 ka cal BP) and the Holocene (ca. 11.69-present). Estimated organic carbon accumulation rates (OCARs) were higher within Holocene sediments (average 3.53 gOCm(-2) a(-1)) than Pleistocene sediments (average 1.08 gOCm(-2) a(-1)) and are similar to those calculated for boreal lakes from Quebec and Finland and Lake Baikal but significantly lower than Siberian thermokarst lakes and Alberta glacial lakes. Using a bootstrapping approach, we estimated the total organic carbon pool to be 0.26 +/- 0.02 Mt and a total sediment pool of 25.7 +/- 1.71 Mt within a hydroacoustically derived sediment volume of ca. 32 990 557m(3). The total organic carbon pool is substantially smaller than Alaskan yedoma, thermokarst lake sediments and Alberta glacial lakes but shares similarities with Finnish boreal lakes. Temporal variability in sediment and carbon accumulation dynamics at Lake Rauchuagytgyn is controlled predominantly by palaeoclimate variation that regulates lake ice-cover dynamics and catchment glacial, fluvial and permafrost processes through time. These processes, in turn, affect catchment and within-lake primary productivity as well as catchment soil development. Spatial differences compared to other lake systems at a trans-regional scale likely relate to the high-latitude, mountainous location of Lake Rauchuagytgyn.}, language = {en} } @article{AlemannoD'AmoreMaturillietal.2022, author = {Alemanno, Giulia and D'Amore, Maddalena and Maturilli, Alessandro and Helbert, Joern and Arnold, Gabriele and Korablev, Oleg and Ignatiev, Nikolay and Grigoriev, Alexei and Shakun, Alexey and Trokhimovskiy, Alexander}, title = {Martian atmospheric spectral end-members retrieval from ExoMars Thermal Infrared (TIRVIM) data}, series = {JGR / Planets}, volume = {127}, journal = {JGR / Planets}, number = {9}, publisher = {Wiley}, address = {Hoboken, NJ}, issn = {2169-9097}, doi = {10.1029/2022JE007429}, pages = {12}, year = {2022}, abstract = {Key knowledge about planetary composition can be recovered from the study of thermal infrared spectral range datasets. This range has a huge diagnostic potential because it contains diagnostic absorptions from a planetary surface and atmosphere. The main goal of this study is to process and interpret the dataset from the Thermal Infrared channel (TIRVIM) which is part of the Atmospheric Chemistry Suite of the ExoMars2016 Trace Gas Orbiter mission to find and characterize dust and water ice clouds in the atmosphere. The method employed here is based on the application of principal component analysis and target transformation techniques to extract the independent variable components present in the analyzed dataset. Spectral shapes of both atmospheric dust and water ice aerosols have been recovered from the analysis of TIRVIM data. The comparison between our results with those previously obtained on Thermal Emission Spectrometer (TES) data and with previous analysis on TIRVIM data, validates the methodology here applied, showing that it allows to correctly recover the atmospheric spectral endmembers present in the TIRVIM data. Moreover, comparison with atmospheric retrievals on PFS, TES and IRIS data, allowed us to assess the temporal stability and homogeneity of dust and water ice components in the Martian atmosphere over a time period of almost 50 years.}, language = {en} } @article{HuelscherSobelVerwateretal.2021, author = {Huelscher, Julian and Sobel, Edward R. and Verwater, Vincent and Gross, Philip and Chew, David and Bernhardt, Anne}, title = {Detrital apatite geochemistry and thermochronology from the Oligocene/Miocene Alpine foreland record the early exhumation of the Tauern Window}, series = {Basin research}, volume = {33}, journal = {Basin research}, number = {6}, publisher = {Wiley}, address = {Hoboken}, issn = {0950-091X}, doi = {10.1111/bre.12593}, pages = {3021 -- 3044}, year = {2021}, abstract = {The early exhumation history of the Tauern Window in the European Eastern Alps and its surface expression is poorly dated and quantified, partly because thermochronological and provenance information are sparse from the Upper Austrian Northern Alpine Foreland Basin. For the first time, we combine a single-grain double-dating approach (Apatite Fission Track and U-Pb dating) with trace-element geochemistry analysis on the same apatites to reconstruct the provenance and exhumation history of the late Oligocene/early Miocene Eastern Alps. The results from 22 samples from the Chattian to Burdigalian sedimentary infill of the Upper Austrian Northern Alpine Foreland Basin were integrated with a 3D seismic-reflection data set and published stratigraphic reports. Our highly discriminative data set indicates an increasing proportion of apatites (from 6\% to 23\%) with Sr/Y values <0.1 up-section and an increasing amount of apatites (from 24\% to 38\%) containing >1,000 ppm light rare-earth elements from Chattian to Burdigalian time. The number of U-Pb ages with acceptable uncertainties increases from 40\% to 59\% up-section, with mostly late Variscan/Permian ages, while an increasing number of grains (10\%-27\%) have Eocene or younger apatite fission track cooling ages. The changes in the apatite trace-element geochemistry and U-Pb data mirror increased sediment input from an >= upper amphibolite-facies metamorphic source of late Variscan/Permian age - probably the otztal-Bundschuh nappe system - accompanied by increasing exhumation rates indicated by decreasing apatite fission track lag times. We attribute these changes to the surface response to upright folding and doming in the Penninic units of the future Tauern Window starting at 29-27 Ma. This early period of exhumation (0.3-0.6 mm/a) is triggered by early Adriatic indentation along the Giudicarie Fault System.}, language = {en} } @article{SilveriiMaccaferriRichteretal.2021, author = {Silverii, Francesca and Maccaferri, Francesco and Richter, Gudrun and Gonzalez Cansado, Borja and Wang, Rongjiang and Hainzl, Sebastian and Dahm, Torsten}, title = {Poroelastic model in a vertically sealed gas storage}, series = {Geophysical journal international / the Royal Astronomical Society, the Deutsche Geophysikalische Gesellschaft and the European Geophysical Society}, volume = {227}, journal = {Geophysical journal international / the Royal Astronomical Society, the Deutsche Geophysikalische Gesellschaft and the European Geophysical Society}, number = {2}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0956-540X}, doi = {10.1093/gji/ggab268}, pages = {1322 -- 1338}, year = {2021}, abstract = {Natural gas can be temporarily stored in a variety of underground facilities, such as depleted gas and oil fields, natural aquifers and caverns in salt rocks. Being extensively monitored during operations, these systems provide a favourable opportunity to investigate how pressure varies in time and space and possibly induces/triggers earthquakes on nearby faults. Elaborate and detailed numerical modelling techniques are often applied to study gas reservoirs. Here we show the possibilities and discuss the limitations of a flexible and easily formulated tool that can be straightforwardly applied to simulate temporal pore-pressure variations and study the relation with recorded microseismic events. We use the software POEL (POroELastic diffusion and deformation) which computes the poroelastic response to fluid injection/extraction in a horizontally layered poroelastic structure. We further develop its application to address the presence of vertical impermeable faults bounding the reservoir and of multiple injection/extraction sources. Exploiting available information on the reservoir geometry and physical parameters, and records of injection/extraction rates for a gas reservoir in southern Europe, we perform an extensive parametric study considering different model configurations. Comparing modelled spatiotemporal pore-pressure variations with in situ measurements, we show that the inclusion of vertical impermeable faults provides an improvement in reproducing the observations and results in pore-pressure accumulation near the faults and in a variation of the temporal pore-pressure diffusion pattern. To study the relation between gas storage activity and recorded local microseismicity, we applied different seismicity models based on the estimated porepressure distribution. This analysis helps to understand the spatial distribution of seismicity and its temporal modulation. The results show that the observed microseismicity could be partly linked to the storage activity, but the contribution of tectonic background seismicity cannot be excluded.}, language = {en} } @article{BueyuekakpınarCescaHainzletal.2021, author = {B{\"u}y{\"u}kakp{\i}nar, P{\i}nar and Cesca, Simone and Hainzl, Sebastian and Jamalreyhani, Mohammadreza and Heimann, Sebastian and Dahm, Torsten}, title = {Reservoir-triggered earthquakes around the Atat{\"u}rk Dam (Southeastern Turkey)}, series = {Frontiers in Earth Science}, volume = {9}, journal = {Frontiers in Earth Science}, publisher = {Frontiers Media}, address = {Lausanne}, issn = {2296-6463}, doi = {10.3389/feart.2021.663385}, pages = {18}, year = {2021}, abstract = {Reservoir-triggered seismicity has been observed near dams during construction, impoundment, and cyclic filling in many parts of the earth. In Turkey, the number of dams has increased substantially over the last decade, with Ataturk Dam being the largest dam in Turkey with a total water capacity of 48.7 billion m(3). After the construction of the dam, the monitoring network has improved. Considering earthquakes above the long-term completeness magnitude of M-C = 3.5, the local seismicity rate has substantially increased after the filling of the reservoir. Recently, two damaging earthquakes of M-w 5.5 and M-w 5.1 occurred in the town of Samsat near the Ataturk Reservoir in 2017 and 2018, respectively. In this study, we analyze the spatio-temporal evolution of seismicity and its source properties in relation to the temporal water-level variations and the stresses resulting from surface loading and pore-pressure diffusion. We find that water-level and seismicity rate are anti-correlated, which is explained by the stabilization effect of the gravitational induced stress imposed by water loading on the local faults. On the other hand, we find that the overall effective stress in the seismogenic zone increased over decades due to pore-pressure diffusion, explaining the enhanced background seismicity during recent years. Additionally, we observe a progressive decrease of the Gutenberg-Richter b-value. Our results indicate that the stressing rate finally focused on the region where the two damaging earthquakes occurred in 2017 and 2018.}, language = {en} } @article{BartschPointnerNitzeetal.2021, author = {Bartsch, Annett and Pointner, Georg and Nitze, Ingmar and Efimova, Aleksandra and Jakober, Dan and Ley, Sarah and H{\"o}gstr{\"o}m, Elin and Grosse, Guido and Schweitzer, Peter}, title = {Expanding infrastructure and growing anthropogenic impacts along Arctic coasts}, series = {Environmental research letters : ERL / Institute of Physics}, volume = {16}, journal = {Environmental research letters : ERL / Institute of Physics}, number = {11}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {1748-9326}, doi = {10.1088/1748-9326/ac3176}, pages = {22}, year = {2021}, abstract = {The accelerating climatic changes and new infrastructure development across the Arctic require more robust risk and environmental assessment, but thus far there is no consistent record of human impact. We provide a first panarctic satellite-based record of expanding infrastructure and anthropogenic impacts along all permafrost affected coasts (100 km buffer, approximate to 6.2 Mio km(2)), named the Sentinel-1/2 derived Arctic Coastal Human Impact (SACHI) dataset. The completeness and thematic content goes beyond traditional satellite based approaches as well as other publicly accessible data sources. Three classes are considered: linear transport infrastructure (roads and railways), buildings, and other impacted area. C-band synthetic aperture radar and multi-spectral information (2016-2020) is exploited within a machine learning framework (gradient boosting machines and deep learning) and combined for retrieval with 10 m nominal resolution. In total, an area of 1243 km(2) constitutes human-built infrastructure as of 2016-2020. Depending on region, SACHI contains 8\%-48\% more information (human presence) than in OpenStreetMap. 221 (78\%) more settlements are identified than in a recently published dataset for this region. 47\% is not covered in a global night-time light dataset from 2016. At least 15\% (180 km(2)) correspond to new or increased detectable human impact since 2000 according to a Landsat-based normalized difference vegetation index trend comparison within the analysis extent. Most of the expanded presence occurred in Russia, but also some in Canada and US. 31\% and 5\% of impacted area associated predominantly with oil/gas and mining industry respectively has appeared after 2000. 55\% of the identified human impacted area will be shifting to above 0 C-circle ground temperature at two meter depth by 2050 if current permafrost warming trends continue at the pace of the last two decades, highlighting the critical importance to better understand how much and where Arctic infrastructure may become threatened by permafrost thaw.}, language = {en} } @article{RoeserDragerBrykalaetal.2021, author = {Roeser, Patricia and Drager, Nadine and Brykala, Dariusz and Ott, Florian and Pinkerneil, Sylvia and Gierszewski, Piotr and Lindemann, Christin and Plessen, Birgit and Brademann, Brian and Kaszubski, Michal and Fojutowski, Michal and Schwab, Markus J. and Slowinski, Michal and Blaszkiewicz, Miroslaw and Brauer, Achim}, title = {Advances in understanding calcite varve formation: new insights from a dual lake monitoring approach in the southern Baltic lowlands}, series = {Boreas : an international journal of quaternary research}, volume = {50}, journal = {Boreas : an international journal of quaternary research}, number = {2}, publisher = {Wiley-Blackwell}, address = {Oxford [u.a.]}, issn = {0300-9483}, doi = {10.1111/bor.12506}, pages = {419 -- 440}, year = {2021}, abstract = {We revise the conceptual model of calcite varves and present, for the first time, a dual lake monitoring study in two alkaline lakes providing new insights into the seasonal sedimentation processes forming these varves. The study lakes, Tiefer See in NE Germany and Czechowskie in N Poland, have distinct morphology and bathymetry, and therefore, they are ideal to decipher local effects on seasonal deposition. The monitoring setup in both lakes is largely identical and includes instrumental observation of (i) meteorological parameters, (ii) chemical profiling of the lake water column including water sampling, and (iii) sediment trapping at both bi-weekly and monthly intervals. We then compare our monitoring data with varve micro-facies in the sediment record. One main finding is that calcite varves form complex laminae triplets rather than simple couplets as commonly thought. Sedimentation of varve sub-layers in both lakes is largely dependent on the lake mixing dynamics and results from the same seasonality, commencing with diatom blooms in spring turning into a pulse of calcite precipitation in summer and terminating with a re-suspension layer in autumn and winter, composed of calcite patches, plant fragments and benthic diatoms. Despite the common seasonal cycle, the share of each of these depositional phases in the total annual sediment yield is different between the lakes. In Lake Tiefer See calcite sedimentation has the highest yields, whereas in Lake Czechowskie, the so far underestimated re-suspension sub-layer dominates the sediment accumulation. Even in undisturbed varved sediments, re-suspended material becomes integrated in the sediment fabric and makes up an important share of calcite varves. Thus, while the biogeochemical lake cycle defines the varves' autochthonous components and micro-facies, the physical setting plays an important role in determining the varve sub-layers' proportion.}, language = {en} }