Last 500 ka Glacial-Interglacial Fingerprints from the Uwa Basin fill deposits, Shikoku

Abstract

Glacial-Interglacial alloformation during the last 500 kyr was found in the 110m long sediment cores drilled at the central part of the Uwa basin, SW Shikoku, Japan. Nine dated tephra layers enabled us to establish a precise age model for the core sediment for the last 500 kyr. Total Organic Carbon, TOC/TN (Total Nitrogen) ratio, grain size distribution, magnetic susceptibility, and lightness, L* were measured and used for multi-proxies, which indicate the core stratigraphic sequence contains at least six lake cycles associated with glacial cycles of the oxygen-isotope stratigraphy. Six pluvial periods with lake deposits can be correlated with MIS 3, 5, 7, 9, 11 and 13, while drier periods with soils and/or peat layers with MIS 2, 6, 8, 10 and 12. These imply that sea-level drop in the glacial periods provided much drier climate to the SW Shikoku.