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 - Nazarova, Larisa B. A1 - Grebennikova, Tatiana A. A1 - Razjigaeva, Nadezhda G. A1 - Ganzey, Larisa A. A1 - Belyanina, Nina I. A1 - Arslanov, Khikmat A. A1 - Kaistrenko, Victor M. A1 - Gorbunov, Aleksey O. A1 - Kharlamov, Andrey A. A1 - Rudaya, Natalia A1 - Palagushkina, Olga A1 - Biskaborn, Boris K. A1 - Diekmann, Bernhard T1 - Reconstruction of Holocene environmental changes in Southern Kurils (North-Western Pacific) based on palaeolake sediment proxies from Shikotan Island JF - Global and planetary change N2 - We investigated a well-dated sediment section of a palaeolake situated in the coastal zone of Shikotan Island (Lesser Kurils) for organic sediment-geochemistry and biotic components (diatoms, chironomids, pollen) in order to provide a reconstruction of the palaeoenvironmental changes and palaeo-events (tsunamis, sea-level fluctuations and landslides) in Holocene. During the ca 8000 years of sedimentation the changes in organic sediment-geochemistry and in composition of the diatoms and chironomids as well as the shifts in composition of terrestrial vegetation suggest that the period until ca 5800 cal yr BP was characterized by a warm and humid climate (corresponds to middle Holocene optimum) with climate cooling thereafter. A warm period reconstructed from ca 900 to at least ca 580 cal yr BP corresponds to a transition to a Nara-Heian-Kamakura warm stage and can be correlated to a Medieval Warm Period. After 580 cal yr PB, the lake gradually dried out and climatic signals could not be obtained from the declining lacustrine biological communities, but the increasing role of spruce and disappearance of the oak from the vegetation give evidences of the climate cooling that can be correlated with the LIA. The marine regression stages at the investigated site are identified for ca 6200-5900 (at the end of the middle Holocene transgression), ca 5500-5100 (Middle Jomon regression or Kemigawa regression), and ca 1070-360 cal yr BP (at the end of Heian transgression). The lithological structure of sediments and the diatom compositions give evidences for the multiple tsunami events of different strengths in the Island. Most remarkable of them can be dated at around ca 7000, 6460, 5750, 4800, 950 cal yr BP. The new results help to understand the Holocene environmental history of the Southern Kurils as a part of the Kuril-Kamchatka and Aleutian Marginal Sea-Island Arc Systems in the North-Western Pacific region. KW - Kurils KW - North-Western Pacific KW - Palaeoclimate KW - Sea level KW - Diatoms KW - Chironomids KW - Pollen Y1 - 2017 U6 - https://doi.org/10.1016/j.gloplacha.2017.10.005 SN - 0921-8181 SN - 1872-6364 VL - 159 SP - 25 EP - 36 PB - Elsevier CY - Amsterdam 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 - 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 -