Reconstruction of deglaciation of Northern Mongolia for the last 330 ka BP, inferred from ostracod stable isotope records from Lake Khubsugul

We have compared δ18O and δ13C compositions of ostracod valves with elemental and grain size records of bottom sediments from the drill core KDP-01 (Northern Mongolia, NM) formed for the last 330 ka BP. The increase in the δ18O values, a high content of Br, and a low percentage of clay particles were found to positively correspond with high lake bio-productivity and “warm” marine isotope stages (MIS-3, 5, 7, and 9) and visa versa during “cold” MIS-stages. Positive δ13C values have been linked with high inflowing dissolved inorganic carbonates, and forest-steppe vegetation seems to be evidenced during “cold” MIS stages (MIS-2, 4, 6, and 8). Sharp depletions in the δ18O values on 1.5–2.5 ‰ occurring during the ends of MIS-6 and MIS-4 could be induced by glacier meltwater discharge into Lake Khubsugul. However, shifts in the δ18O values were not significant in MIS-2 and MIS-8, based on our assumption that the inflow rates of glacier meltwater were low due to the relatively small sizes of glaciers in the NM during these stages. During MIS-2, Northern Mongolian glaciers were the smallest in sizes due to high regional aridity. The climate condition in MIS-3 was not typically favorable for a “warm” MIS-stage, while glaciers or snow patches formed in MIS-4 most likely were still in the NM. As a result, isotopically depleted δ18O meltwater was supplied into Lake Khubsugul at the period.