NEW DATA ON THE GEOCHRONOLOGY OF QUATERNARY SEDIMENTS AND STABLE OXYGEN AND HYDROGEN ISOTOPES IN GROUND ICE OF THE MAMONTOVA GORA
N.V. Torgovkin1, D.E. Sivtsev1,2, A.A. Gavrilova3, I.A. Platonov2, A.I. Kizyakov2, L. Schirrmeister4, T. Opel4, S. Wetterich5, S.F.M. Breitenbach6, H. Meyer4
1Melnikov Permafrost Institute, Siberian Branch of the Russian Academy of Sciences, Yakutsk, Russia
2Lomonosov Moscow State University, Geography Department, Moscow, Russia
3Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, St. Petersburg, Russia
4Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, Potsdam, Germany
5TUD Dresden University of Technology, Institute of Geography, Dresden, Germany
6Northumbria University, Department of Earth and Environmental Sciences, Newcastle-Upon-Tyne, United Kingdom
Keywords: ice complex, lacustrine-alluvial sediments, OSL dating, ground ice, stable oxygen and hydrogen isotopes, paleoclimate, Middle and Late Pleistocene
Abstract
The results of studies of the Ice Complex, lacustrine, and lacustrine-alluvial sediments from the Mamontova Gora section performed in 2022-2023 are analyzed. Optically stimulated luminescence dating indicates that the formation of the lacustrine-alluvial sands of the Elga Group ended 250-242 ka ago, at the end of cold MIS 8, while the overlying lacustrine silts accumulated until 138-126 ka ago corresponding to the late cold MIS 6 - early warm MIS 5e. The average isotopic composition of the Yedoma Ice Complex (MIS 3) syngenetic wedge ice is -(31 ± 2)‰ for δ18O, -(239 ± 15)‰ for δD, and (8 ± 2)‰ for dexc. For the first time, we quantify the isotopic composition of the Yedoma Ice Complex textural ice with the average values of -(26 ± 2)‰ for δ18O, -(201 ± 17)‰ for δD, and (10 ± 4)‰ for dexc. The formation of lacustrine and lacustrine-alluvial sequences during MIS 7 and MIS 5e was fostered by warmer and likely longer thaw periods and associated permafrost thaw. The degree of warming remains to be estimated for this region.
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