[M-IS01] Environmental, socio-economic, and climatic changes in Northern Eurasia

[MIS01-P02] Statistical approach on geochemical records from Lake Olgoy, Valley of the Gobi Lakes, Mongolia

*Uyangaa Udaanjargal¹, Noriko Hasebe², Davaadorj Davaasuren, Yudai Igarashi¹, Hitoshi Hasegawa³, Baasansuren Gankhurel¹, Nagayoshi Katsuta⁴, Shuukhaaz Ganbat¹, Ichinnorov Niiden, Keisuke Fukushi² (1.Department of Earth Sciences, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan, 2.Institute of Nature and Environmental Technology, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan, 3.Faculty of Science and Technology, Kochi University, Kochi 780-8520, Japan, 4.Faculty of Education, Gifu University, Gifu 501-1193, Japan)

Keywords:major and trace elements, principal component analysis, sediment characteristics, Olgoy lake

Mongolia is located in northern Central Asia and provides an important key archive for research on the past environment in the region. To assess the regional paleoenvironment, this study analyzed a 10.5 m sediment core retrieved from Olgoy lake in the west-central part of Mongolia. The sedimentary features are investigated as environmental proxies, including whole and mineral grain size, water, organic matter, carbonate, amorphous silica contents, and variations in elements analyzed by X-ray fluorescence. The core was divided into three units based on lithology and analytical results: Unit I with clayey sediment, Unit II with silty sediment, and Unit III with sand and gravel. Principal component analysis (PCA) was applied to the 18 major and trace elements, and they were divided into terrigenous (Al, Si, K, Rb, Zr, Cd, and Pb as the first principal component, and Cr, Fe, Zn, and Ti as the second principal component), authigenic (Ca, Mn, and Sr), and melting (S and Br) inputs. PCA provided insight on the correlation between the sediment characteristics and elemental data. PCA variables demonstrated that lithogenic elements transported by the alluvial or aeolian processes are the principal component through the whole core. The PCA score showed a significant difference in each unit. In-lake chemical productivity, indicated by elements found in authigenic materials, was most active during the LGM and, so far in early Pleistocene in the Olgoy lake sediment.