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系统的粒度测量和沉积动力学研究发现,中国黄土由粗粒与细粒组分叠加组成,粗粒组分主要是低空季风环流产生的粉尘沉积;细粒组分代表主要由高空西风环流控制的背景粉尘。不同剖面粗粒组分的变化一致表明,低空季风环流在冰期加强,在间冰期减弱;细粒组分变化序列在纬向的分异特征显示,冰期时西风环流加强、同时西风急流南移至约35°N,间冰期西风环流减弱且急流北移至约37°N。最近2.6Ma洛川剖面粒度组分变化趋势表明,西风环流对风尘沉积的贡献减小、强度减弱,与此同步,季风环流对风尘沉积的贡献增加、强度增大,其中最显著的变化发生在1.2～0.9Ma前,可能指示了青藏高原隆升对中更新世中国北方大气环流转型的决定性作用。
The results of particle size measurement and sedimentation kinetics show that the Chinese loess is composed of superfine and fine-grained components, and the coarse-grained components are mainly dust deposition produced by low-level monsoon circulation. The fine-grained components represent mainly controlled by the upper-level westerly circulation Background dust. The consistent changes of the coarse-grained components in different sections show that the circulation of the low-level monsoon intensified during the glacial period and weakened during the interglacial period. The zonal differentiation of the fine-grained composition sequence showed that during the glacial period, the westerly circulation strengthened and the westerly jet stream moved southward to At about 35 ° N, the westerly circulation weakened during the interglacial period and the jet stream moved northward to about 37 ° N. The trend of the grain size component in the recent 2.6Ma Luochuan section shows that the contribution of the westerly circulation to dust deposition decreases and the intensity decreases. Simultaneously with this, the contribution of the monsoon circulation to dust deposition increases and its intensity increases, with the most significant change occurring in Before 1.2 ~ 0.9Ma, it may indicate the decisive role of the Qinghai-Tibet Plateau uplift in the transformation of the atmospheric circulation in North China during the Middle Pleistocene.