Holocene Landform Evolution of Lake Khuvsgul basin, Mongolia

Abstract

This study presents landform evolution within the lake Khuvsgul basin (also known as Hovsgol and Khubsugul) in northern Mongolia during the Holocene: beach bars, spits, lake terraces and fluvial processes (sediment and organic components) in the River Borsog which flows into the lake. Lake Borsog, an eastern former bay of Lake Khuvsgul, separated from Lake Khuvsgul during its post-glacial transgression and possesses high-resolution record of the Holocene landscape evolution. Sedimentary sequence of a 13 m long core BB03 from Lake Borsog shows three short-term events of higher-sedimentation rate at 7.4-7.1 ka cal. BP, 4.8-4.5 ka cal. BP and 1.0-0.9 ka cal. BP, which are possibly related to drops in lake level, reductions of lake area, progradation of the delta of the Borsog River and erosion of the exposed lake shores. The drops in the lake level match the previously documented drops of the level of Lake Khuvsgul at ca. 7.2-7.0, 4.5-4.1 and 2.1-0.5 ka cal. BP, suggesting continued mutually-related and climatically-controlled evolutions of both lakes after their separation.