Abstract
This study aims to reconstruct paleo-environments since 30 ka from the viewpoint of the characteristics of eolian dust and fluvial materials at Hosoike moor in the Chugoku Mountains, western Japan. We collected 2 boring cores 3 meters deep from the moor, which is located at 960 meters asl., on the Chugoku mountain ridge. The moor deposits, which have accumulated for 30 ka, consist of peat, silt, silt with organic matter, sand and gravel, and 4 tephras K-Ah, SUk, DHg, and AT. These deposits can be classified as fluvial material and eolian dust on the basis of the characteristics of ESR oxygen vacancy and grain size distribution. The fluvial material consists of coarse grain of more than 30 μm, while eolian dust consists of a finer material of less than 20μm. Peaks of lithogenic matter density, which consists of fluvial material, may be correlated with Interstadials 1 to 4, as indicated by the GRIP climate record. Fluvial materials were deposited during warmer, wetter periods such as the interstadial periods, whereas eolian dust was deposited during the drier colder periods of MIS 2 and 3. As Hosoike moor was located north of the polar front during MIS 2 and 3, eolian dust was transported from the pre-Cambrian rock areas of north Asia by northwesterly winds. During MIS 1, eolian dust is transported from the Chinese inland deserts by westerly winds.
