OXYGEN ISOTOPIC COMPOSITION IN DIATOM ALGAE FRUSTULES FROM LAKE BAIKAL SEDIMENTS: ANNUAL MEAN TEMPERATURE VARIATIONS DURING THE LAST 40 KA

Abstract

The oxygen isotopic compositions of ice sheets in Antarctica and Greenland and biogenic carbonates from deep-sea oceanic sediments represent a source of reliable information on global climate changes. During glaciations, the 16O-rich isotope is largely accumulated in polar ice sheets, while seawater becomes enriched in 18O. Warming promotes glacier melting and concentration of the oxygen light isotope in atmospheric moisture and seawater. This is recorded in remains of biogenic carbonate organisms, for example, shells of fossil foraminifers.