[M-IS16] 古気候・古海洋変動

[MIS16-P27] 白亜紀湖成層コアに記録される千年周期成分の抽出：モンテカルロ法による年代不確定性の検討

*長谷川 精¹、朝日 博史² (1.高知大学理工学部、2.高知大学海洋コア総合研究センター)

キーワード：年縞、千年周期、年代不確実性、モンテカルロ法

Detail paleoclimatic records under exceptionally warm “hothouse” condition provide crucial insights toward future climate predictions. However, climatic variations in millennial-scale at such deep-time archives commonly faces difficulties owing to the large uncertainties of absolute age at more than hundred kyr-scale. Annually laminated lacustrine deposits of Early Aptian (ca. 123–119 Ma) in southeast Mongolia firstly enable to obtain millennial- and shorter time-scale climate variability at such immemorial period. By combining μm-scale analysis of fluorescence microscopy images (seasonal resolution) and ultra-high-resolution elemental XRF scanning techniques (~1–5 year resolution), we were able to generate a continental climate record of unrivalled temporal resolution. Age model of the subject core was established at annual- to decadal time-scale, taking account a casual relation of ITRAX elemental composition and (annually formed) varve thickness. FFT power spectrum of high temporal resolution and long duration ITRAX record, with consideration of maximum age uncertainties (Monte-Carlo approach), exhibit partial presences of millennial-scale extreme drought events during the mid-Cretaceous ‘hothouse’ periods.