Freshwater ostracodes in Quaternary permafrost deposits in the Siberian Arctic

摘要

Ostracode analysis was carried out on samples from ice-rich permafrost deposits obtained on the Bykovsky Peninsula (Laptev Sea). A composite pro. le was investigated that covers most of a 38-m thick permafrost sequence and corresponds to the last ca. 60 kyr of the Late Quaternary. The ostracode assemblages are similar to those known from European Quaternary lake deposits during cold stages. The ostracode habitats were small, shallow, cold, oligotrophic pools located in low centred ice wedge polygons or in small thermokarst depressions. In total, 15 taxa, representing 7 genera, were identified from 65 samples. The studied section is subdivided into six ostracode zones that correspond to Late Quaternary climatic and environmental stadial-interstadial variations established by other paleoenvironmental proxies: (1) cold and dry Zyrianian stadial (58 - 53 kyr BP); (2) warm and dry Karginian interstadial (48 - 34 kyr BP); (3) transition from the Karginian interstadial to the cold and dry Sartanian stadial (34 - 21 kyr BP); (4) transition from the Sartanian stadial to the warm and dry Late Pleistocene period, the Allerod (21 - 14 kyr BP); ( 5) transition from the Allerod to the warm and wet Middle Holocene (14 - 7 kyr BP); and ( 6) cool and wet Late Holocene (ca. 3 kyr BP). The abundance and diversity of the ostracodes will be used as an additional bioindicator for paleoenvironmental reconstructions of the Siberian Arctic.