The Quaternary Research (Daiyonki-Kenkyu)

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Loess began its deposition at the beginning of the Quaternary. Through the enlargement of glaciers and deserts during the glacial stages, the productivity, depositional volume, and grain size of eolian dust increased. In East Asia, huge amounts of eolian dust have also been deposited on the land surface of various localities and sea floors by westerly winds and the northwestern winter monsoon blown from the Siberian High. The significance of eolian dust study has been recognized in Japan and Korea since the 1980s. Evidence from drilling cores of ocean floors and lands in East Asia has suggested that eolian dust and loess show a clear relationship between dust flux maxima and glacial stages, and depositional volume of eolian dust can also be used as a paleo-environmental indicator. Several periods of enhanced dust deposition derived from the Asian glaciers and deserts to China, Korea, Japan, and peripheral sea floors can be correlated with cold periods such as Heinrich events. Eolian dust additions to soils also made important contributions to primary productivity in East Asia during the Holocene. The alternation of loess and paleosol has been regarded as an excellent proxy record of the strength of Asian summer and winter monsoons over the past 2.6 Myr. Accordingly, loess-paleosol stratigraphy constitutes an important record of variations in the East Asia monsoon climate. Among the methods of analyzing the loess from various areas, ESR signal intensity of finer quartz grain than 20m is a useful marker for the identity of eolian dust and its resource area. Paleolithic chronology can be determined by loess-paleosol sequences in China, Korea, and Japan. A paleolith from Itazu site, Izumo City in Japan was discovered from a MIS 6 loess layer.

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