INSOLATION REGIME IN SIBERIA AS A MAJOR FACTOR CONTROLLING DIATOM PRODUCTION IN LAKE BAIKAL DURING THE PAST 800,000 YEARS

Abstract

A unique diatom biostratigraphy of the Brunhes chron in Lake Baikal revealed by detailed studies of pelagic diatom paleo-assemblages, indicates that dramatic changes in insolation during the past 800 ka BP produced surprisingly rapid diatom speciation and extinctions. The orbitally-tuned age model allows the diatom assemblages to be compared with individual marine isotopic stages and substages during the Brunhes. Most of the interglacial periods are characterized by explosive speciation and appearances of new pelagic planktonic diatom species. In contrast, most of the glacial periods are characterized by spectacular extinctions.