日本地球惑星科学連合2014年大会

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ポスター発表

セッション記号 M (領域外・複数領域) » M-IS ジョイント

[M-IS30_28PO1] 古気候・古海洋変動

2014年4月28日(月) 18:15 〜 19:30 3階ポスター会場 (3F)

コンビーナ:*山田 和芳(早稲田大学人間科学学術院)、池原 実(高知大学海洋コア総合研究センター)、入野 智久(北海道大学 大学院地球環境科学研究院)、岡崎 裕典(九州大学大学院理学研究院地球惑星科学部門)、北場 育子(神戸大学内海域環境教育研究センター)、北村 晃寿(静岡大学理学部地球科学教室)、佐野 雅規(総合地球環境学研究所)、多田 隆治(東京大学大学院理学系研究科地球惑星科学専攻)、吉森 正和(東京大学大気海洋研究所)

18:15 〜 19:30

[MIS30-P17] モンゴル北部のレス-古土壌シーケンスから復元する最終氷期~完新世のアジア中緯度域の気候変動

オルホンセレンゲ アレクサンドラ1、*長谷川 精2 (1.モンゴル国立大学地理地質学科、2.名古屋大学博物館)

キーワード:モンゴル, レス-古土壌シーケンス, 偏西風, 冬季モンスーン, 完新世, 最終氷期

Two atmospheric circulation systems, the mid-latitude Westerlies and the Asian monsoon, play key roles in northern-hemisphere climatic changes. However, the variability of the Westerlies in mid-latitude Asia and their relationship to the Asian summer and winter monsoon remain unclear. We examined the variations in the grain size and elemental composition from the 30 m long loess-paleosol succession in Shaamar area, northern Mongolia, which could be recorded the interplay of the Westerlies and Asian winter monsoon for the last 30 k.y. We then compared our results with the multi-proxy paleoclimate records (e.g., eolian grain sizes, lake levels, pollen assemblages) of the Asian summer and winter monsoon regions and the Westerlies affected region.
According to the compiled data of the Wang and Feng (2013), the Holocene climatic variation patterns (mainly from lake levels and pollen records) in Asia are categorized into 4 characteristic regions, such as the Summer monsoon region (southern and northeastern China), Westerlies affected region (northwestern China), Winter monsoon region (southern Siberia), and Mixture of westerlies and winter monsoon affected region (Mongolia). Specifically, summer monsoon region is characterized by dry earliest Holocene (12-11 ka), humid early to middle Holocene (11-6 ka), and the moderate-humid late Holocene (last 6 ka), corresponding to the Northern hemisphere summer insolation changes. Westerlies affected region is characterized by dry early Holocene (12-8 ka) and humid middle to late Holocene (last 8 ka). Winter monsoon region is characterized by the humid early Holocene (12-8 ka) and dry middle to late Holocene (last 8 ka). On the other hand, Mongolian records (e.g., Lake Khuvsgul, Lake Gun Nuur) demonstrate humid early Holocene (12-9 ka), dry middle Holocene (9-5 ka), and humid late Holocene (last 5 ka), which seems mixture of westerlies and winter monsoon affected region.
Shaamar loess-paleosol succession record is characterized by the humid early Holocene (12-8 ka) and dry middle to late Holocene (last 8 ka), similar to the winter monsoon region in southern Siberia. Thus, it is suggested that the eolian sediment record in Shaamar could be affected more strongly by winter monsoon influence, although Shaamar section is located closely to the mixture of westerlies and winter monsoon affected region (e.g., Lake Khuvsgul and Lake Gun Nuur). Except for the Chinese Loess Plateau, Shaamar loess-paleosol succession is only the continuous eolian sediment record in mid-latitude Asia. Thus, Shaamar loess-paleosol succession should provide us rare glimpse for understanding the interplay of westerlies and winter monsoon in Asian mid-latitude. We will further examine the Last glacial records of the Shaamar loess-plaeosol succession and compare with other records of the Asian summer and winter monsoon regions and the Westerlies affected region.