Paleoenvironmental Changes during the Past 110, 000 Years in the Nakaikemi Basin and the Kuroi Basin, Central Japan

We studied two drilling cores from the Naka-ikemi basin which was deposited during the past 110, 000 years in Fukui Prefecture and the Kuroi basin, which was deposited during the last glacial period in Hyogo Prefecture in central Japan, to reconstruct paleoenvironmental changes from eolian dust deposition. We suggest that two the cores show records of the East Asian monsoon variability correlated to the cool Younger Dryas and Heinrich events H1-H6, and to interglacial/interstadial periods, such as the Dansgaard-Oescheger IS1-IS24 climate intervals, respectively, as seen in the Greenland temperature record. Eolian dust in the two areas was transported from the North Asian continent by the NW winter monsoon judging from the high electron spin resonance (ESR) signal intensity. Periods of strong NW winter monsoon, indicated by eolian dust spikes, were associated with atmospheric cooling and the development of the Siberian high pressure systems. Following every eolian dust spike, the mean diameter of inorganic material increased abruptly. It seems that the increases of grain size reflect fluvial activity induced by the summer monsoon, which correlated with interstadial and interglacial climatic events.