Tracing recent glacial events in bottom sediments of a glacial lake (East Sayan Ridge, Russia) from high‐resolution SR‐XRF, ICP‐MS, and FTIR records

Abstract

The paper presents a study of bottom sediments of proglacial Lake Ehoy, which intakes the meltwater of Peretolchin glacier, the East Sayan Ridge. A bottom sediment sequence that formed in the period of 1885–2013 was investigated with a year/season time resolution using X‐ray fluorescence with synchrotron radiation and conventional analysis. A depth‐age model of the core was based on counting of the annual laminae. The model was checked by an analysis of the distribution of activity of 210Pb, 137Cs, 238U, and 226Ra. The dynamics of the glacier is considered through the intensity of clastic material inflow into the lake with the glacier melt water. In the elemental composition of the sediments, there are three groups of elements that reflect the periods of movement of the front edge of the glacier and the intensity of development of the aquatic biota. The first group of elements (Ca, K, Ti, Fe, and Mn) characterizes the inflow of clastic material when there are no significant changes in the boundaries of the glacier. The second group of elements (Ni, Cu, Br, and U) reflects the aquatic biota intensity. The third group of elements (Rb, Sr, Zr, Nb, Y, and Th) is some evidence that the displacement of the front edge of the glacier was significant. The glacier retreated rapidly in 1947–1970. The next period of steady degradation of the glacier took place in 1980–2000. Since 2000, the melting rate has slowed down. Copyright © 2015 John Wiley & Sons, Ltd.