Pleistocene-Holocene paleoclimate record of Lake Baikal

Investigation of the paleoclimatic history of continental interiors are important to our understanding of the continental responses of Central Asia to orbital forcing and tectonic uplift of orogenic systems. The objective of this dissertation is to present new paleoclimate results deduced from biogenic silica and diatom paleoclimate record of sediment cores drilled in Lake Baikal (Southern Siberia).; The modern existing paleoclimate records of inner Asia and proxies used for paleoclimate reconstructions in Siberia and particularly in Lake Baikal area are discussed and the importance of the Lake Baikal sedimentary record as paleoclimate archive of continental climate processes is demonstrated in dissertation. The key role of biogenic silica content for paleoclimate record is presented. The major aspects of biogenic silica as a proxy are discussed: as a paleoproductivity index, and as a highly sensitive indicator of how the East Siberia and Lake Baikal ecosystem respond to climate change.; The paleoclimatic record from bottom sediments of Lake Baikal reveals new evidence for an abrupt and intense glaciation during the initial part of the last interglacial period (isotope substage 5d). This glaciation lasted about 12,000 years from 117,000 to 105,000 yrs BP according to the correlation with SPECMAP isotope chronology. The severe 5d glaciation in Siberia was caused by dramatic cooling due to the decrease in solar insolation (as predicted by the model of insolation changes for Northern Asia according to Milankovich theory) coupled with western atmospheric transport of moisture from the open areas of Northern Atlantic and Arctic seas (which became ice-free due to the intense warming during preceding isotope substage 5e).; New results from sediment cores of Lake Baikal represent large and abrupt climate changes of the Central Asia during the last 450 kyr and suggest that climate instability in Central Asia region are very close to climate instability of North Atlantic region what were recently discovered in Greenland ice-cores and some marine and terrestrial climate records.; Correlation of Baikal records with the marine isotopic records shows good agreement and surprisingly similar shapes of peaks of both records. However, apart from the good correlation of the Baikal opal record and marine oxygen isotopic record, there are many important differences in the Baikal records which present the peculiarity of the continental climate response of Central Asia to orbital forcing.