A ROCK-MAGNETIC RECORD FROM LAKE BAIKAL, SIBERIA - EVIDENCE FOR LATE QUATERNARY CLIMATE-CHANGE

Rock-magnetic measurements of sediment cores from the Academician Ridg e region of Lake Baikal, Siberia show variations related to Late Quate rnary climate change. Based upon the well-dated last glacial-interglac ial transition, variations in magnetic concentration and mineralogy ar e related to glacial-interglacial cycles using a conceptual model. Int erglacial intervals are characterized by low magnetic concentrations a nd a composition that is dominated by low coercivity minerals. Glacial intervals are characterized by high magnetic concentrations and incre ased amounts of high coercivity minerals. The variation in magnetic co ncentration is consistent with dilution by diatom opal during the more productive interglacial periods. We also infer an increased contribut ion of eolian sediment during the colder, windier, and more arid glaci al conditions when extensive loess deposits were formed throughout Eur ope and Asia. Eolian transport is inferred to deliver increased amount s of high coercivity minerals as staining on eolian grains during the glacial intervals. Variations in magnetic concentration and mineralogy of Lake Baikal sediment correlate to the SPECMAP marine oxygen-isotop e record. The high degree of correlation between Baikal magnetic conce ntration/mineralogy and the SPECMAP oxygen-isotope record indicates th at Lake Baikal sediment preserves a history of climate change in centr al Asia for the last 250 ka. This correlation provides a method of est imating the age of sediment beyond the range of the radiocarbon method . Future work must include providing better age control and additional climate proxy data, thereby strengthening the correlation of continen tal and marine climate records.