East Asian monsoon variation during the last 130,000 Years: evidence from the Loess Plateau of central China and Lake Biwa of Japan

The loess-paleosol sequence on the Loess Plateau of central China constitut es an excellent proxy record of variations in Asian monsoon climate over th e past 2.5 Ma. Magnetic susceptibility of loess and paleosols has been used as a proxy indicator for summer monsoon intensity, while the median diamet er of quartz isolated from the loess and paleosols has been regarded as a p roxy index of the strength of winter monsoon winds that were responsible fo r most of the dust transport. The eolian quartz flux to Lake Biwa of centra l Japan during the last 130,000 yr provides direct information on variation s of the East Asian winter monsoon; whereas the fluvial quartz flux reflect s significant changes in paleoprecipitation over the lake area. The interva ls of high eolian quartz flux values during marine oxygen isotope substages 5d and 5b, and stages 4 and 2 correspond to the periods of large quartz me dian diameter values of the Chinese loess and paleosols, indicating strengt hened winter monsoon winds; whereas the intervals of high fluvial quartz fl ux values during isotope substages 5e, 5c, and 5a, and stages 3 and 1 corre late to the periods of high magnetic susceptibility values of the Chinese l oess and paleosols, suggesting increased summer monsoon intensity. Variatio ns in winter monsoon strength indicated by the eolian quartz flux and quart z median diameter proxies bear a general inverse relation to those in summe r monsoon intensity inferred from the fluvial quartz flux and magnetic susc eptibility proxies. (C) 1998 Elsevier Science Ltd. All rights reserved.