[M-IS23] [JJ] 古気候・古海洋変動

[MIS23-P27] ボナパルト湾の海洋堆積物とglacial isostatic adjustmentモデルによる海洋酸素同位体ステージ2の海水準変動復元

*石輪 健樹¹、横山 祐典¹、奥野 淳一²、上原 克人³、池原 実⁴、オブラクタ スティーブン⁵ (1.東京大学大気海洋研究所、2.国立極地研究所、3.九州大学応用力学研究所、4.高知大学海洋コア総合研究所、5.秋田大学)

キーワード：海水準変動、GIA model、海洋酸素同位体ステージ2、放射性炭素年代測定

Marine Isotope Stage 2 (MIS 2) is the latest glacial period (30,000–15,000 years ago), including the Last Glacial Maximum (LGM) characterized by the maximum of global ice volume. The comparison of various paleoclimatic records with sea-level change derives an understanding of the earth climate system. However, global sea-level change during MIS 2, especially the LGM, is less understood due to its paucity of data and its uncertainty. The Bonaparte Gulf, northwestern Australia, is a suitable region to reconstruct the global sea level change since the Gulf is far from the former ice sheet and tectonically stable. Here we present the new sea-level records from the Bonaparte Gulf and the revision of the global ice volume history during the MIS 2 using marine sediment cores, paleo-tidal model and glacial isostatic adjustment (GIA) model. To reconstruct relative sea level in the Bonaparte Gulf, we employed exceeding 250 radiocarbon dates of carbonates and bulk organic matters from cores with various depths, combined with the two-dimensional tidal model for the evaluation of paleo-tidal effects to the past sea level in the Bonaparte Gulf. We also propose the revised global ice volume history during the MIS 2 based on results from GIA model and the new relative sea-level records for the Bonaparte Gulf.