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黄土地球化学残积系数、钠钙比和化学风化指数数值增大、退碱系数数值减小时,指示化学风化作用增强,在很大程度上揭示出当时具有较强的夏季风活动。延安地区延长剖面末次间冰期残积系数、钠钙比和化学风化指数的曲线具有三峰两谷,揭示了一系列亚轨道时间尺度的夏季风波动变化,能分辨出多个次级气候旋回。因此,黄土的地球化学参数可以作为本区指示夏季风波动的敏感性指标。
The value of geochemical residual coefficient, sodium-calcium ratio and chemical weathering index of loess increased, and when the value of de-alkali coefficient decreased, the chemical weathering was enhanced, which revealed to a large extent the strong summer monsoon activity. The curve of residual coefficient, sodium-calcium ratio and chemical weathering index of the last interglacial glacial phase in Yan’an section has three peaks and two valleys, revealing a series of sub-orbital time-scale variations of summer monsoon, and distinguishing multiple secondary climate cycles. Therefore, the geochemical parameters of loess can be used as a sensitive indicator of the summer monsoon fluctuations in this area.