The Lithology and Inorganic Geochemistry from Achit Lake Sediments as an Indicator of Paleoclimatic Change, Western Mongolia

Abstract

Lithology and inorganic geochemical elements were investigated for a sediment core from Achit Lake, western Mongolia and the Chemical Index of Alteration (CIA) was calculated. Based on the results, the paleoclimatic changes in western Mongolia are reconstructed. The high content of SiO₂, Al₂O₃, TiO₂, Fe₂O₃, K₂O and Na₂O and the active layer of CIA are correlated with variable warm climate (climatic transitional period; from~13200 to 6400 and from~1600 to 0 cal yr BP). However, the high contents of easily soluble elements, such as MgO and CaO, with the inactive layer of CIA are corresponded to the cold climate (from ~22600 to ~13200 cal yr BP and from ~6400 to ~1600 cal yr BP). These lead to that geochemical elements of Lake Achit sediment and Chemical Index of Alteration are closely related to climatic changes in western Mongolia of the late Pleistocene and the Holocene.