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黄土的粒度分析是重建古气候的常用手段之一.基于Tsoar和Pye(1987)提出的粉尘搬运模型,通过沿风力搬运方向的两个黄土剖面的粒度变化,构建了定量估算粉尘源区-沉积区距离的模型.采集环县和白马铺古土壤S_2以上(250ka以来)的粒度数据,运用该模型得出了粉尘源区-沉积区的距离.结果表明,间冰期古土壤发育时期,源区-沉积区距离较远,沙漠南缘至环县剖面距离约为340km;冰期黄土堆积时期,源区-沉积区距离较近,沙漠南缘至环县剖面距离约为100km.该定量重建结果表明,250ka以来的冰期-间冰期旋回中,沙漠南缘的进退变化距离约为240km,验证了东亚夏季风降水控制沙漠进退从而影响黄土-古土壤粒度变化的机制.
Based on the dust handling model proposed by Tsoar and Pye (1987), the grain size of two loess sections along the direction of wind transport is used to build a quantitative estimation of dust source area - sediment The distance between the source and the source area of the paleosol during the period of paleosol development in the interglacial period was taken as the model to collect the grain size data above the S_2 (since 250 ka) - the sedimentary area is far away, the distance from the southern margin of the desert to the Huanxian section is about 340km; during the accumulation of glacial loess, the distance between the source area and the sedimentary area is relatively close, and the distance from the southern edge of the desert to the Huanxian section is about 100km. During the glacial-interglacial cycles since 250 ka, the advancing and retreating distance of the southern margin of the desert is about 240 km, which verifies that the mechanism of East Asian summer monsoon rainfall controlling desert advance and retreat and affecting the grain size of the loess-paleosol.