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  - Lenz, Josefine
A1  - Grosse, Guido
A1  - Jones, Benjamin M.
A1  - Anthony, Katey M. Walter
A1  - Bobrov, Anatoly
A1  - Wulf, Sabine
A1  - Wetterich, Sebastian
T1  - Mid-Wisconsin to Holocene Permafrost and Landscape Dynamics based on a Drained Lake Basin Core from the Northern Seward Peninsula, Northwest Alaska
JF  - Permafrost and Periglacial Processes
N2  - Permafrost-related processes drive regional landscape dynamics in the Arctic terrestrial system. A better understanding of past periods indicative of permafrost degradation and aggradation is important for predicting the future response of Arctic landscapes to climate change. Here, we used a multi-proxy approach to analyse a4m long sediment core from a drained thermokarst lake basin on the northern Seward Peninsula in western Arctic Alaska (USA). Sedimentological, biogeochemical, geochronological, micropalaeontological (ostracoda, testate amoebae) and tephra analyses were used to determine the long-term environmental Early-Wisconsin to Holocene history preserved in our core for central Beringia. Yedoma accumulation dominated throughout the Early to Late-Wisconsin but was interrupted by wetland formation from 44.5 to 41.5ka BP. The latter was terminated by the deposition of 1m of volcanic tephra, most likely originating from the South Killeak Maar eruption at about 42ka BP. Yedoma deposition continued until 22.5ka BP and was followed by a depositional hiatus in the sediment core between 22.5 and 0.23ka BP. We interpret this hiatus as due to intense thermokarst activity in the areas surrounding the site, which served as a sediment source during the Late-Wisconsin to Holocene climate transition. The lake forming the modern basin on the upland initiated around 0.23ka BP and drained catastrophically in spring 2005. The present study emphasises that Arctic lake systems and periglacial landscapes are highly dynamic and that permafrost formation as well as degradation in central Beringia was controlled by regional to global climate patterns as well as by local disturbances. Copyright (c) 2015 John Wiley & Sons, Ltd.
KW  - Beringia
KW  - palaeoenvironmental reconstruction
KW  - thermokarst lake dynamics
KW  - cryostratigraphy
KW  - tephra
KW  - bioindicators
KW  - yedoma
Y1  - 2016
U6  - https://doi.org/10.1002/ppp.1848
SN  - 1045-6740
SN  - 1099-1530
VL  - 27
SP  - 56
EP  - 75
PB  - Wiley-Blackwell
CY  - Hoboken
ER  -