THE EXTENT, STYLE AND CHRONOLOGY OF GLACIATION IN NORTHEAST RUSSIA

Although field evidence for multiple glaciations exists in NE Russia, only the Sartan (LGM) advance and retreat has been well dated and documented. The extent and chronology of glaciation in this region was previously based on air photo interpretation and correlation methods, respectively. Recently, we have used 10Be, 26Al and 36Cl cosmogenic isotope dating on erratics, tors and other bedrock outcrops to decipher glacial chronologies. Exposure ages confirm that the style of glaciation was limited to cirques and valley glaciers during the Sartan (20 ka). Pre-LGM glaciations are marked by subdued moraines with exposure ages >30 ka and associated non-finite radiocarbon dates.

A systematic study of Late Glacial/Holocene glaciations in NE Russia is lacking; although other paleoenvironmental records suggest significant climate change in this region. The restricted nature of glaciations is most likely due to moisture limitations. During glacial maximums, the now submerged, wide continental shelf surrounding NE Russia was emergent; leading to increased continentality of the region. Surrounding oceans were covered with sea ice; thereby precluding them as a viable moisture source to nourish glacier growth. Our conclusion on the limited extent of glaciation is consistent with modeling studies of restricted moisture transport during the LGM across the central and eastern Russian Arctic.