Reconstructing hydrological variability in Lake Baikal during MIS 11 : an application of oxygen isotope analysis of diatom silica

In this paper we reconstruct hydrological variability in Lake Baikal during Marine Isotope Stage 11 (MIS 11) (427-362 ka BP) from oxygen isotope analysis of diatom silica. Highest 18Odiatom values are found during MIS 11.3, highlighting the dominance of hydrological input from rivers flowing into the south and central basins of Lake Baikal, especially the Selenga River. Hydrological input from south basin rivers dominated for over 30 ka. However, there is evidence from both biogenic silica and 18Odiatom records for an abrupt cooling event at ca. 390 ka BP. Stadial conditions at this time are coincident with an iceberg discharge event into the North Atlantic. The decline in 18Odiatom values suggests increasing proportion of hydrological input from rivers to the north of Lake Baikal, due to greater influence of winter precipitation and snow-melt. After a period of interstadial conditions during the early stages of MIS 11.1, biogenic silica and 18Odiatom values decline, mirroring the slow growth in Northern Hemisphere ice sheets. Despite rigorous cleaning procedures, palaeoclimatic inferences need to be treated with caution due to contamination of the 18Odiatom record; during stadial and glacial periods, contamination of the 18Odiatom record is even more significant.