Changes in patterns of mineral and chemical elements in bottom sediments of Lake Baikal (Russia) as high-resolution records of moisture for the past 31–16 ka BP

Abstract

The high-resolution biochemical records (SRXRF, ICP-MS and FTIR analyses) of bottom sediments were used for the reconstruction of clastic flux into Lake Baikal via the Barguzin River as moisture and glacier indexes from 1631 ka BP. According to the obtained data, proxies of a high supply of clastic flux by the river are high: the content of feldspar and LREE/HREE, Rb/Sr and Th/Mo ratios. We sampled a sediment core extremely close to the estuary of the Barguzin River. It seems that the water budget of the Baikal tributaries dramatically reduced ca. 34–30 ka BP, and the lake water level was minimum (less than 35–40 m compared to the present) for the last 34 ka. The lake water level has gradually increased from ca. 30 to 25–23 ka BP, and it was likely linked with the activity of the East Asia Monsoon. The very contrasting changes in chemical and mineralogical records were ca. 29.5 ka BP, and these changes were very likely associated with the Heinrich-3; however, there were no significant changes in the records around the Heinrich-2. Our records revealed some intensification of the clastic flux of the Barguzin River into the Barguzin Bay ca. 25–23 ka BP. The Baikal event ca. 21.5–22.5 ka BP was characterized by a sharp reduction of the influx of clastic material into the Barguzin Bay. The time span of 19.5–18 ka BP was the last time that the Barguzin River inflow increased during the Late Pleistocene. This increase in the water budget was at arid regional conditions, and we assumed it could occur due to the contribution of meltwater from glaciers of the Barguzin Ridge. It is most likely that at the regional Late Pleistocene/Holocene transition (around 12–13 ka BP), a rapid rise of the water budget of the Barguzin River occurred, while the lake level was not high, and the sediments deposited from 12(13)–16.5 ka BP could be directly eroded by a kill of the Barguzin River. In general, the obtained records show that an increase in the water budget of the Barguzin River was gradual. The duration of high inflow into the Barguzin Bay was ca. 1.5 ka, while the reductions of this inflow were dramatic.