OXYGEN AND CARBON ISOTOPE VARIATIONS IN OSTRACODE SHELLS FROM LAKE HUBSUGUL (MONGOLIA) AND REGIONAL PALEOCLIMATE CHANGES FOR THE LAST 140 KA

Abstract

It was established in the middle of the past century that δ18O and δ13C values in biogenic carbonates are correlated with variations in the climate and basin productivity. These variations are most contrasting in the isotopic composition of lacustrine species. The large freshwater Lake Hubsugul, the second basin in size after Baikal, is located in the northern part of Central Asia at 1645 masl and extends in the meridional direction over 136 km. It is 20 km wide and 139 m deep on the average. The maximal depth is 262 m. The high carbonate content in lake waters [2] is favorable for development of ostracodes with carbonate shells.