Новые данные о геохронологии четвертичных отложений и стабильных изотопах кислорода и водорода в подземных льдах Мамонтовой Горы

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 d ¹⁸O, –(239 ± 15)% for dD, and (8 ± 2)% for d _exc. For the first time, we quantify the isotopic composition of the Yedoma Ice Complex textural ice with the average values of –(26 ± 2)% for d ¹⁸O, –(201 ± 17)% for dD, and (10 ± 4)% for d _exc. 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.