Quartz from selected horizons of loess-paleosol sequence on the Chinese Loess Plateau and the Osaka Group of central Japan

Quartz has been isolated from the Sandy Loess of loess-paleosol sequence on the Loess Plateau and non-marine clay in the Osaka Group. Oxygen isotope composition of quartz from non-marine clay in the Osaka Group remarkably varies with the grainsize fractions, which implies that quartz grains of different size fractions were derived from geochemically distinct sources. Grain-size distribution of quartz illustrates that non-marine clay in the Osaka Group was subjected to various sedimentary environments during different geological periods, i.e., prevailing transportation alternated between the transport by the wind (including in situ) and by local surface waters as the paleoenvironment changed. Grain-size distribution and oxygen isotope composition of quartz isolated from Chinese Sandy Loess and non-marine clay in the Osaka Group suggest that the content of fine-grained quartz contained in clay sediments in Japan recorded, to a certain extent, the intensity of Asian winter monsoon, and would be supposed to play an important part in the reconstruction of the history of Asian monsoon variation during the Quaternary. -from Authors