East Siberian glaciers have contracted over the last two glacial cycles
- 1Department of Geoscience, Aarhus University, Aarhus, Denmark
- 2Department of Physical Geography and Geoecology, Charles University, Prague, Czechia
- 3GFÚ Institute of Geophysics, Czech Academy of Sciences, Prague, Czechia
- 4Institute of Water Problems, Hydropower and Ecology, National Academy of Sciences of Tajikistan
- 5Institute of Geoinformation and Geoecology, Adam Mickiewicz University, Poznań, Poland
- 6Department of Physical Geography, Stockholm University, Stockholm, Sweden
- 7Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark
- 8Rubenstein School for Environment and Natural Resources, University of Vermont, Burlington, VT, United States
Satellite-based maps of glacial landforms reveal that the mountain landscapes of northeast Eurasia contain over one million km2 of glaciated terrain. Previous work has speculated on the existence of large ice masses during the Last Glacial Maximum (LGM) and the preceding cold phases, but the lack of age constraints means that little is known about the timing of past glaciations across this vast region.
With an aim to gain a better understanding of the glacial history of this region, we collected samples for cosmogenic 10Be exposure dating of boulder erratics and moraines in the mountains of eastern Siberia. Here, we present the first results from two sites, both within the Chersky Range: (1) Malyk Sen, which contains a succession of three end moraines in a foreland setting; and (2) Ust-Nera, which features boulder erratics and glacial bedrock pavement exposed in a previously glaciated valley. At Malyk Sen, the relative positions and corresponding ages of the three moraines indicate progressive contraction of maximum glacier extent since termination of the Marine Isotope Stage (MIS) 6, with the innermost moraine dated to the LGM. Our preliminary results from Ust-Nera suggest exposure ages from glacially-transported boulders and bedrock pavement that are significantly older than the LGM. Both sites indicate limited extents of mountain glaciation during the LGM in eastern Siberia. And while the glacial chronology of our study does not extend beyond MIS 6, mapping of the surrounding areas indicates that even more expansive glaciers existed further back in time.
Our findings confirm the trend of successively smaller glacial extent maxima’s in continental Eurasia towards the LGM, with at least one ice advance during MIS 5-3 larger than the LGM advance. This trend could to be linked to extreme continental settings such as in Eurasia and westernmost America, as it contrasts with larger parts of the Northern Hemisphere glaciations where Late Pleistocene maxima were reached during LGM.
How to cite: Nørgaard, J., Margold, M., D. Jansen, J., Kurbanov, R., Szuman-Kalita, I., Lund Andersen, J., Olsen, J., Faurschou Knudsen, M., Corbett, L., and Bierman, P.: East Siberian glaciers have contracted over the last two glacial cycles, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-6150, https://doi.org/10.5194/egusphere-egu23-6150, 2023.
