TY - JOUR A1 - Schennen, Stephan A1 - Tronicke, Jens A1 - Wetterich, Sebastian A1 - Allroggen, Niklas A1 - Schwamborn, Georg A1 - Schirrmeister, Lutz T1 - 3D ground-penetrating radar imaging of ice complex deposits in northern East Siberia JF - Geophysics N2 - Ice complex deposits are characteristic, ice-rich formations in northern East Siberia and represent an important part in the arctic carbon pool. Recently, these late Quaternary deposits are the objective of numerous investigations typically relying on outcrop and borehole data. Many of these studies can benefit from a 3D structural model of the subsurface for upscaling their observations or for constraining estimations of inventories, such as the local carbon stock. We have addressed this problem of structural imaging by 3D ground-penetrating radar (GPR), which, in permafrost studies, has been primarily used for 2D profiling. We have used a 3D kinematic GPR surveying strategy at a field site located in the New Siberian Archipelago on top of an ice complex. After applying a 3D GPR processing sequence, we were able to trace two horizons at depths below 20 m. Taking available borehole and outcrop data into account, we have interpreted these two features as interfaces of major lithologic units and derived a 3D cryostratigraphic model of the subsurface. Our data example demonstrated that a 3D surveying and processing strategy was crucial at our field site and showed the potential of 3D GPR to image geologic structures in complex ice-rich permafrost landscapes. Y1 - 2016 U6 - https://doi.org/10.1190/GEO2015-0129.1 SN - 0016-8033 SN - 1942-2156 VL - 81 SP - WA195 EP - WA202 PB - Society of Exploration Geophysicists CY - Tulsa ER - TY - JOUR A1 - Wolter, Juliane A1 - Lantuit, Hugues A1 - Wetterich, Sebastian A1 - Rethemeyer, Janet A1 - Fritz, Michael T1 - Climatic, geomorphologic and hydrologic perturbations as drivers for mid- to late Holocene development of ice-wedge polygons in the western Canadian Arctic JF - Permafrost and Periglacial Processes N2 - Ice-wedge polygons are widespread periglacial features and influence landscape hydrology and carbon storage. The influence of climate and topography on polygon development is not entirely clear, however, giving high uncertainties to projections of permafrost development. We studied the mid- to late Holocene development of modern ice-wedge polygon sites to explore drivers of change and reasons for long-term stability. We analyzed organic carbon, total nitrogen, stable carbon isotopes, grain size composition and plant macrofossils in six cores from three polygons. We found that ail sites developed from aquatic to wetland conditions. In the mid-Holocene, shallow lakes and partly submerged ice-wedge polygons existed at the studied sites. An erosional hiatus of ca 5000 years followed, and ice-wedge polygons re-initiated within the last millennium. Ice-wedge melt and surface drying during the last century were linked to climatic warming. The influence of climate on ice-wedge polygon development was outweighed by geomorphology during most of the late Holocene. Recent warming, however, caused ice-wedge degradation at all sites. Our study showed that where waterlogged ground was maintained, low-centered polygons persisted for millennia. Ice-wedge melt and increased drainage through geomorphic disturbance, however, triggered conversion into high-centered polygons and may lead to self-enhancing degradation under continued warming. KW - carbon KW - lowland coasts KW - permafrost degradation KW - plant macrofossil analysis KW - tundra vegetation KW - western Canadian Arctic Y1 - 2018 U6 - https://doi.org/10.1002/ppp.1977 SN - 1045-6740 SN - 1099-1530 VL - 29 IS - 3 SP - 164 EP - 181 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Palagushkina, Olga A1 - Wetterich, Sebastian A1 - Biskaborn, Boris K. A1 - Nazarova, Larisa B. A1 - Schirrmeister, Lutz A1 - Lenz, Josefine A1 - Schwamborn, Georg A1 - Grosse, Guido T1 - Diatom records and tephra mineralogy in pingo deposits of Seward Peninsula, Alaska JF - Palaeogeography, palaeoclimatology, palaeoecology : an international journal for the geo-sciences N2 - Vast areas of the terrestrial Subarctic and Arctic are underlain by permafrost. Landscape evolution is therefore largely controlled by climate-driven periglacial processes. The response of the frozen ground to late Quaternary warm and cold stages is preserved in permafrost sequences, and deducible by multi-proxy palaeoenvironmental approaches. Here, we analyse radiocarbon-dated mid-Wisconsin Interstadial and Holocene lacustrine deposits preserved in the Kit-1 pingo permafrost sequence combined with water and surface sediment samples from nine modern water bodies on Seward Peninsula (NW Alaska) to reconstruct thermokarst dynamics and determine major abiotic factors that controlled the aquatic ecosystem variability. Our methods comprise taxonomical diatom analyses as well as Detrended Correspondence Analysis (DCA) and Redundancy Analysis (RDA). Our results show, that the fossil diatom record reflects thermokarst lake succession since about 42 C-14 kyr BP. Different thermolcarst lake stages during the mid-Wisconsin Interstadial, the late Wisconsin and the early Holocene are mirrored by changes in diatom abundance, diversity, and ecology. We interpret the taxonomical changes in the fossil diatom assemblages in combination with both modern diatom data from surrounding ponds and existing micropalaeontological, sedimentological and mineralogical data from the pingo sequence. A diatom based quantitative reconstruction of lake water pH indicates changing lake environments during mid-Wisconsin to early Holocene stages. Mineralogical analyses indicate presence of tephra fallout and its impact on fossil diatom communities. Our comparison of modern and fossil diatom communities shows the highest floristic similarity of modern polygon ponds to the corresponding initial (shallow water) development stages of thermolcarst lakes. We conclude, that mid-Wisconsin thermokarst processes in the study area could establish during relatively warm interstadial climate conditions accompanied by increased precipitation due to approaching coasts, while still high continentality and hence high seasonal temperature gradients led to warm summers in the central part of Beringia. (C) 2017 Elsevier B.V. All rights reserved. KW - Microalgae assemblages KW - Palaeoenvironments KW - Thermokarst KW - Late Quaternary KW - Permafrost Y1 - 2017 U6 - https://doi.org/10.1016/j.palaeo.2017.04.006 SN - 0031-0182 SN - 1872-616X VL - 479 SP - 1 EP - 15 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Lenz, Josefine A1 - Wetterich, Sebastian A1 - Jones, Benjamin M. A1 - Meyer, Hanno A1 - Bobrov, Anatoly A1 - Grosse, Guido T1 - Evidence of multiple thermokarst lake generations from an 11800-year-old permafrost core on the northern Seward Peninsula, Alaska JF - Boreas N2 - Permafrost degradation influences the morphology, biogeochemical cycling and hydrology of Arctic landscapes over a range of time scales. To reconstruct temporal patterns of early to late Holocene permafrost and thermokarst dynamics, site-specific palaeo-records are needed. Here we present a multi-proxy study of a 350-cm-long permafrost core from a drained lake basin on the northern Seward Peninsula, Alaska, revealing Lateglacial toHolocene thermokarst lake dynamics in a central location of Beringia. Use of radiocarbon dating, micropalaeontology (ostracods and testaceans), sedimentology (grain-size analyses, magnetic susceptibility, tephra analyses), geochemistry (total nitrogen and carbon, total organic carbon, C-13(org)) and stable water isotopes (O-18, D, dexcess) of ground ice allowed the reconstruction of several distinct thermokarst lake phases. These include a pre-lacustrine environment at the base of the core characterized by the Devil Mountain Maar tephra (22800 +/- 280cal. a BP, Unit A), which has vertically subsided in places due to subsequent development of a deep thermokarst lake that initiated around 11800cal. a BP (Unit B). At about 9000cal. a BP this lake transitioned from a stable depositional environment to a very dynamic lake system (Unit C) characterized by fluctuating lake levels, potentially intermediate wetland development, and expansion and erosion of shore deposits. Complete drainage of this lake occurred at 1060cal. a BP, including post-drainage sediment freezing from the top down to 154cm and gradual accumulation of terrestrial peat (Unit D), as well as uniform upward talik refreezing. This core-based reconstruction of multiple thermokarst lake generations since 11800cal. a BP improves our understanding of the temporal scales of thermokarst lake development from initiation to drainage, demonstrates complex landscape evolution in the ice-rich permafrost regions of Central Beringia during the Lateglacial and Holocene, and enhances our understanding of biogeochemical cycles in thermokarst-affected regions of the Arctic. Y1 - 2016 U6 - https://doi.org/10.1111/bor.12186 SN - 0300-9483 SN - 1502-3885 VL - 45 SP - 584 EP - 603 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Schneider, Andrea A1 - Wetterich, Sebastian A1 - Schirrmeister, Lutz A1 - Herzschuh, Ulrike A1 - Meyer, Hanno A1 - Pestryakova, Luidmila Agafyevna T1 - Freshwater ostracods (Crustacea) and environmental variability of polygon ponds in the tundra of the Indigirka Lowland, north-east Siberia JF - Polar research : a Norwegian journal of Polar research N2 - Freshwater ostracods (Crustacea, Ostracoda) are valuable biological indicators. In Arctic environments, their habitat conditions are barely known and the abundance and diversity of ostracods is documented only in scattered records with incomplete ecological characterization. To determine the taxonomic range of ostracod assemblages and their habitat conditions in polygon ponds in the Indigirka Lowland, north-east Siberia, we collected more than 100 living ostracod individuals per site with a plankton net (mesh size 65 mm) and an exhaustor system from 27 water bodies and studied them in the context of substrate and hydrochemical data. During the summer of 2011, a single pond site and its ostracod population was selected for special study. This first record of the ostracod fauna in the Indigirka Lowland comprises eight species and three additional taxa. Fabaeformiscandona krochini and F. groenlandica were documented for the first time in continental Siberia. Repeated sampling of a low-centre polygon pond yielded insights into the population dynamics of F. pedata. We identified air temperature and precipitation as the main external drivers of water temperatures, water levels, ion concentrations and water stable isotope composition on diurnal and seasonal scales. KW - Arctic limnology KW - permafrost KW - patterned ground KW - ecological indication KW - freshwater ostracods Y1 - 2016 U6 - https://doi.org/10.3402/polar.v35.25225 SN - 0800-0395 SN - 1751-8369 VL - 35 PB - Society of Exploration Geophysicists CY - Abingdon ER - TY - THES A1 - Wetterich, Sebastian T1 - Freshwater ostracods as bioindicators in Arctic periglacial regions Y1 - 2008 CY - Potsdam ER - TY - JOUR A1 - Overduin, Pier Paul A1 - Westermann, Sebastian A1 - Yoshikawa, Kenji A1 - Haberlau, Thomas A1 - Romanovsky, Vladimir E. A1 - Wetterich, Sebastian T1 - Geoelectric observations of the degradation of nearshore submarine permafrost at Barrow (Alaskan Beaufort Sea) JF - Journal of geophysical research : Earth surface N2 - Submarine permafrost degradation rates may be determined by a number of interacting processes, including rates of sea level rise and coastal erosion, sea bottom temperature and salinity regimes, geothermal heat flux and heat and mass diffusion within the sediment column. Observations of ice-bearing permafrost in shelf sediments are necessary in order to determine its spatial distribution and to quantify its degradation rate. We tested the use of direct current electrical resistivity to ice-bearing permafrost in Elson Lagoon northeast of Barrow, Alaska (Beaufort Sea). A sharp increase in electrical resistivity was observed in profiles collected perpendicular to and along the coastline and is interpreted to be the boundary between ice-free sediment and underlying ice-bearing submarine permafrost. The depth to the interpreted ice-bearing permafrost increases from <2 m below sea level to over 12 m below sea level with increasing distance from the coastline. The dependence of the saline sediment electrical resistivity on temperature and freezing was measured in the laboratory to provide validation for the field measurements. Electrical resistivity was shown to be effective for detection of shallow ice-bearing permafrost in the coastal zone. Historical coastal retreat rates were combined with the inclination of the top of the ice-bearing permafrost to calculate mean vertical permafrost degradation rates of 1 to 4 cm yr(-1). Y1 - 2012 U6 - https://doi.org/10.1029/2011JF002088 SN - 0148-0227 VL - 117 IS - 14 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Fritz, Michael A1 - Wolter, Juliane A1 - Rudaya, Natalia A1 - Palagushkina, Olga A1 - Nazarova, Larisa B. A1 - Obu, Jaroslav A1 - Rethemeyer, Janet A1 - Lantuit, Hugues A1 - Wetterich, Sebastian T1 - Holocene ice-wedge polygon development in northern Yukon permafrost peatlands (Canada) JF - Quaternary science reviews : the international multidisciplinary research and review journal N2 - Ice-wedge polygon (IWP) peatlands in the Arctic and Subarctic are extremely vulnerable to climatic and environmental change. We present the results of a multidisciplinary paleoenvironmental study on IWPs in the northern Yukon, Canada. High-resolution laboratory analyses were carried out on a permafrost core and the overlying seasonally thawed (active) layer, from an IWP located in a drained lake basin on Herschel Island. In relation to 14 Accelerator Mass Spectrometry (AMS) radiocarbon dates spanning the last 5000 years, we report sedimentary data including grain size distribution and biogeochemical parameters (organic carbon, nitrogen, C/N ratio, delta C-13), stable water isotopes (delta O-18, delta D), as well as fossil pollen, plant macrofossil and diatom assemblages. Three sediment units (SUS) correspond to the main stages of deposition (1) in a thermokarst lake (SW : 4950 to 3950 cal yrs BP), (2) during transition from lacustrine to palustrine conditions after lake drainage (SU2: 3950 to 3120 cal yrs BP), and (3) in palustrine conditions of the IWP field that developed after drainage (SU3: 3120 cal yrs BP to 2012 CE). The lacustrine phase (pre 3950 cal yrs BP) is characterized by planktonic-benthic and pioneer diatom species indicating circumneutral waters, and very few plant macrofossils. The pollen record has captured a regional signal of relatively stable vegetation composition and climate for the lacustrine stage of the record until 3950 cal yrs BP. Palustrine conditions with benthic and acidophilic diatom species characterize the peaty shallow-water environments of the low-centered IWP. The transition from lacustrine to palustrine conditions was accompanied by acidification and rapid revegetation of the lake bottom within about 100 years. Since the palustrine phase we consider the pollen record as a local vegetation proxy dominated by the plant communities growing in the IWP. Ice-wedge cracking in water-saturated sediments started immediately after lake drainage at about 3950 cal yrs BP and led to the formation of an IWP mire. Permafrost aggradation through downward closed-system freezing of the lake talik is indicated by the stable water isotope record. The originally submerged IWP center underwent gradual drying during the past 2000 years. This study highlights the sensitivity of permafrost landscapes to climate and environmental change throughout the Holocene. (C) 2016 Elsevier Ltd. All rights reserved. KW - Permafrost peatlands KW - Arctic KW - Thermokarst KW - Talik KW - Ice-wedge polygon KW - Pollen KW - Diatoms KW - Plant macrofossils KW - Stable water isotopes KW - Deuterium excess Y1 - 2016 U6 - https://doi.org/10.1016/j.quascirev.2016.02.008 SN - 0277-3791 VL - 147 SP - 279 EP - 297 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Wetterich, Sebastian A1 - Schirrmeiste, Lutz A1 - Nazarova, Larisa B. A1 - Palagushkina, Olga A1 - Bobrov, Anatoly A1 - Pogosyan, Lilit A1 - Savelieva, Larisa A1 - Syrykh, Liudmila A1 - Matthes, Heidrun A1 - Fritz, Michael A1 - Günther, Frank A1 - Opel, Thomas A1 - Meyer, Hanno T1 - Holocene thermokarst and pingo development in the Kolyma Lowland (NE Siberia) JF - Permafrost and Periglacial Processes N2 - Ground ice and sedimentary records of a pingo exposure reveal insights into Holocene permafrost, landscape and climate dynamics. Early to mid-Holocene thermokarst lake deposits contain rich floral and faunal paleoassemblages, which indicate lake shrinkage and decreasing summer temperatures (chironomid-based T-July) from 10.5 to 3.5 cal kyr BP with the warmest period between 10.5 and 8 cal kyr BP. Talik refreezing and pingo growth started about 3.5 cal kyr BP after disappearance of the lake. The isotopic composition of the pingo ice (delta O-18 - 17.1 +/- 0.6 parts per thousand, delta D -144.5 +/- 3.4 parts per thousand, slope 5.85, deuterium excess -7.7 +/- 1.5 parts per thousand) point to the initial stage of closed-system freezing captured in the record. A differing isotopic composition within the massive ice body was found (delta O-18 - 21.3 +/- 1.4 parts per thousand, delta D -165 +/- 11.5 parts per thousand, slope 8.13, deuterium excess 4.9 +/- 3.2 parts per thousand), probably related to the infill of dilation cracks by surface water with quasi-meteoric signature. Currently inactive syngenetic ice wedges formed in the thermokarst basin after lake drainage. The pingo preserves traces of permafrost response to climate variations in terms of ground-ice degradation (thermokarst) during the early and mid-Holocene, and aggradation (wedge-ice and pingo-ice growth) during the late Holocene. KW - bioindicators KW - cryolithology KW - hydrochemistry KW - Khalerchinskaya tundra KW - stable water isotopes Y1 - 2018 U6 - https://doi.org/10.1002/ppp.1979 SN - 1045-6740 SN - 1099-1530 VL - 29 IS - 3 SP - 182 EP - 198 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Wetterich, Sebastian A1 - Rudaya, Natalia A1 - Kuznetsov, Vladislav A1 - Maksimov, Fedor A1 - Opel, Thomas A1 - Meyer, Hanno A1 - Günther, Frank A1 - Bobrov, Anatoly A1 - Raschke, Elena A1 - Zimmermann, Heike Hildegard A1 - Strauss, Jens A1 - Starikova, Anna A1 - Fuchs, Margret A1 - Schirrmeister, Lutz T1 - Ice Complex formation on Bol'shoy Lyakhovsky Island (New Siberian Archipelago, East Siberian Arctic) since about 200 ka JF - Quaternary research : an interdisciplinary journal N2 - Late Quaternary landscapes of unglaciated Beringia were largely shaped by ice-wedge polygon tundra. Ice Complex (IC) strata preserve such ancient polygon formations. Here we report on the Yukagir IC from Bol'shoy Lyakhovsky Island in northeastern Siberia and suggest that new radioisotope disequilibria (230Th/U) dates of the Yukagir IC peat confirm its formation during the Marine Oxygen Isotope Stage (MIS) 7a–c interglacial period. The preservation of the ice-rich Yukagir IC proves its resilience to last interglacial and late glacial–Holocene warming. This study compares the Yukagir IC to IC strata of MIS 5, MIS 3, and MIS 2 ages exposed on Bol'shoy Lyakhovsky Island. Besides high intrasedimental ice content and syngenetic ice wedges intersecting silts, sandy silts, the Yukagir IC is characterized by high organic matter (OM) accumulation and low OM decomposition of a distinctive Drepanocladus moss-peat. The Yukagir IC pollen data reveal grass-shrub-moss tundra indicating rather wet summer conditions similar to modern ones. The stable isotope composition of Yukagir IC wedge ice is similar to those of the MIS 5 and MIS 3 ICs pointing to similar atmospheric moisture generation and transport patterns in winter. IC data from glacial and interglacial periods provide insights into permafrost and climate dynamics since about 200 ka. KW - Cryostratigraphy KW - Ice wedges KW - Stable isotopes KW - Pollen KW - Radioisotope disequilibria dating KW - Beringia Y1 - 2019 U6 - https://doi.org/10.1017/qua.2019.6 SN - 0033-5894 SN - 1096-0287 VL - 92 IS - 2 SP - 530 EP - 548 PB - Cambridge Univ. Press CY - New York ER -