中国中部黄土高原における13万年前以降の冬期季節風の強さの変遷--粒度組成による推定〔英文〕

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The median diameter (Md) of grain size distribution of three loess-paleosol sequences from the Loess Plateau of central China has provided a critical evidence for the variation of winter monsoon intensity in this region during the last 130, 000 years. The median grain size (Md) value is regarded as a direct measure of the intensity of the winter monsoon which transported dust grains; the higher the Md value, the stronger the winter monsoon. Median grain size curves of the three sections indicate presences of three distinct periods of finer dust grains separated by two intervals of coarser dust grains. The median grain sizes were finer during the periods of 130, 000-73, 000yrs BP, 60, 000-25, 000yrs BP and 10, 000-5, 000 yrs BP, which indicates that the winter monsoon were weak during these periods. In the intervals of 73, 000-60, 000yrs BP and 25, 000-10, 000yes BP, the Md values increased progressively, reflecting that winter monsoon were strong. At about 18, 000yrs BP, the median grain size shows a peak of coarsening, implying an extremely intensified winter monsoon during the Last Glacial maximum. Our results demonstrate that the median grain size is an excellent index for the winter monsoon variations during the Late Quaternary.
日本第四紀学会の論文