[M-IS16] Paleoclimatology and paleoceanography

[MIS16-P27] Millennial-scale cyclicities recorded in the Cretaceous lacustrine core using Monte Carlo approach

*Hitoshi Hasegawa¹, Hirofumi Asahi² (1.Faculty of Science and Technology, Kochi University, 2.Center for Advanced Marine Core Research, Kochi University)

Keywords:Varve, Millennial-scale cyclicity, Age uncertainty, Monte Carlo approach

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.