Late-Pleistocene (MIS 3-2) palaeoenvironments as recorded by sediments,palaeosols, and ground-squirrel nests at Duvanny Yar,Kolyma lowland,northeast Siberia

A detailed study of the Duvanny Yar section in the Kolyma Lowland (Yakutia) provides the most extensive knowledge to date about late-Pleistocene soil formation processes and environments in the North–East Siberian Arctic. Late-Quaternary palaeoenvironmental changes were reconstructed using paleopedological data and a range of palaeoecological bio-indicators (palynomorphs, plant macrofossils and insects). The frozen sediments representing marine isotope stage 3 (MIS-3), which encompasses the Karginsky interstadial, include profiles of four palaeosols of different ages. The oldest palaeosol is early Karginskian, and three overlying soil horizons represent a late-Karginskian pedocomplex. Palaeopedological data indicate a change of from synlithogenic soil formation processes to epigenic ones during these intervals. The intervening periods of synlithogenic pedogenesis were accompanied by active accumulation of eolian deposits. The Earlier Karginskian period of pedogenesis occurred in the absence of eolian sedimentation and when summer conditions were warm. The wide spectrum of peaty and peaty-gley soils observed in the late-Karginskian deposits developed under conditions of progressive cooling. The structure and content of fossil rodent burrows dated to approximately 30 000 yr BP from frozen late-Pleistocene deposits at Duvanny Yar indicate an arid and severe climate, a depth of active layer of 60–80 cm, and a wide distribution of disturbed habitats with pioneer and steppe vegetation.