[M-IS05] 新生代におけるアジアモンスーンおよびインド太平洋古気候

[MIS05-01] 過去168万年間の西部太平洋暖水塊の水文学

*山本 正伸¹、菊池 壮平¹、山本 洋司¹、ボバ サマンサ²、ロゼンタール ヤイール² (1.北海道大学大学院地球環境科学研究院、2.ラトガース大学)

キーワード：西部太平洋暖水塊、熱帯収束帯、更新世

The hydrology of the Western Pacific Warm Pool (WPWP) region is a key element of the earth’s climate, which sensitively responds to greenhouse gas concentration, insolation, hemispheric energy balance, Hadley and Walker circulations, interhemispheric monsoons and El Niño-Southern Oscillation. The behaviors of the WPWP hydrology are not fully understood on a glacial-interglacial timescale. In this study, we generated a 1.68 Myr records of sea surface temperature (SST) and precipitation from IODP Site U1486 based on TEX₈₆ and the cyclization index of branched GDGTs (CBT). The SST varied 26.5 and 30.5°C, showing a pattern similar to variations in global ice volume and atmospheric CO₂ concentration. The greenhouse gas effect was a most likely factor determining the SST at Site U1486. Soil organic matter contribution, expressed as the CBT, shows a strong precession cycle. The precipitation maxima in northern New Guinea was anti-phased with the minima of Chinese stalagmite δ¹⁸O on a precession cycle, suggesting a common forcing of hydrology in the WPWP and East Asia.