Biogenic silica records from the BDP93 drill site and adjacent areas of the Selenga Delta, Lake Baikal, Siberia

Biogenic silica contents of sediments on the lower Selenga Delta and Buguld eika saddle in Lake Baikal show distinct fluctuations that reflect changes in diatom productivity, and ultimately, climate. The pattern of the upper 5 0 m of the section, dating from about 334 ka, is similar to that of the mar ine oxygen-isotope record, increasingly so as the younger sediments become progressively finer grained and less locally derived with time. The last tw o interglaciations are marked by biogenic silica abundances similar to thos e of the Holocene. The equivalent of marine oxygen-isotope stage 3 is disti nctly intermediate in character between full glacial and full interglacial biogenic silica values. Following near-zero values during the last glacial maximum, biogenic silica began to increase at about 13 ka. The rise in biog enic silica to Holocene values was interrupted by an abrupt decrease during Younger Dryas time, about 11 to 10 C-14 ka.