[MIS19-P14] モンゴル南西部オログ湖堆積物から復元される最終氷期～完新世の古環境変動とホモ・サピエンス定着との関係性
キーワード：湖底堆積物、塩湖、古環境変動、ダンスガードイベント、ホモ・サピエンス、上部旧石器時代初期および前期
An aim of the present study is to understand detailed paleoenvironmental changes in Mongolia, situated at a key crossroad for Homo sapiens's migration between central, eastern, and northern Asia during the Initial and Early Upper Paleolithic (IUP-EUP). Available archaeological evidences have suggested the emergence of IUP at around ca. 45-40 ka (e.g., Zwyns et al., 2014; Rybin et al., 2016; Izuho et al., 2018). However, yet the paleoenvironmental changes of this period in Mongolia is largely unclear, preventing us to understand whether the possible environmental changes were significant as a major driving forth for modern human’s lifeway.
In this paper, we present a new record of paleoenvironmental changes in southwestern Mongolia during MIS 3. In January 2017, we took two parallel cores (OROG01, 24 m; OROG02, 21 m) from Orog Lake, a shallow saline lake located in northwestern margin of Gobi Desert. The high-resolution major and minor element composition changes were obtained using μXRF core scanner (Cox, Itrax) at Center for Advanced Marine Core Research, Kochi University. Based on the preliminary results of OSL and 14C age dating, basal age of sediment core OROG01 yielded ca. 38 ±4 ka, nearly accordant with the basal age of ~45 ka reported in the previous study (Yu et al., 2019). On the basis of our high-resolution elemental composition data, in conjunction with previous sedimentological and palynological data (Yu et al., 2019), the paleoenvironments of southwestern Mongolia were more humid with higher lake levels during MIS 3 than Holocene. Our results also suggest periodic and higher amplitude paleoenvironmental changes in this region, which likely correspond to Dansgaard-Oeschger events. This new record would allow us to discuss potential relationship between paleoenvironmental changes and ecosystem changes in Mongolia during the IUP-EUP.
In this paper, we present a new record of paleoenvironmental changes in southwestern Mongolia during MIS 3. In January 2017, we took two parallel cores (OROG01, 24 m; OROG02, 21 m) from Orog Lake, a shallow saline lake located in northwestern margin of Gobi Desert. The high-resolution major and minor element composition changes were obtained using μXRF core scanner (Cox, Itrax) at Center for Advanced Marine Core Research, Kochi University. Based on the preliminary results of OSL and 14C age dating, basal age of sediment core OROG01 yielded ca. 38 ±4 ka, nearly accordant with the basal age of ~45 ka reported in the previous study (Yu et al., 2019). On the basis of our high-resolution elemental composition data, in conjunction with previous sedimentological and palynological data (Yu et al., 2019), the paleoenvironments of southwestern Mongolia were more humid with higher lake levels during MIS 3 than Holocene. Our results also suggest periodic and higher amplitude paleoenvironmental changes in this region, which likely correspond to Dansgaard-Oeschger events. This new record would allow us to discuss potential relationship between paleoenvironmental changes and ecosystem changes in Mongolia during the IUP-EUP.