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对环县、长武和渭南3个剖面末次间冰期以来黄土-古土壤样品进行了粘粒(<2μm)提取,采用X射线衍射分析技术对粘粒样品的伊利石结晶度,即KI值(1.0nm衍射峰的半高宽)进行时空变化分析。结果表明,环县剖面的KI值在黄土-古土壤中差异不大,而中南部的长武与渭南剖面能很好地反映冰期与间冰期旋回特征;在空间上,古土壤S_0和S_1的KI值自西北向东南呈现逐渐增加趋势,而黄土L_1层仅在最南部的渭南剖面呈现较高的值,环县和长武剖面差异不大,均呈现较低的值。综合分析影响黄土KI值变化的各个因素后,认为风化成壤作用可能是影响黄土-古土壤伊利石结晶度指标变化的主要因素,可以作为东亚夏季风环流强度演化的指标。
Loess-paleosol samples were extracted from clay samples (<2μm) from the last interglacial in the three sections of Huanxian, Changwu and Weinan. The X-ray diffraction (XRD) 1.0nm diffraction peak full width at half maximum) for spatiotemporal variation analysis. The results show that there is no obvious difference in the KI value of the loess-paleosol between the Huanxian section and the Changwu and Weinan sections in central and southern China, which can well reflect the glacial and interglacial cycle characteristics. In space, the S_0 and S_1 KI value tends to increase gradually from the northwest to the southeast, while the L_1 layer of the loess shows a higher value only in the weinan section of the southernmost part, while there is no obvious difference between the sections of Huanxian and Changwu, all showing lower values. After comprehensively analyzing the various factors affecting the change of KI of loess, we conclude that weathering and pedogenesis may be the main factors affecting the change of illite crystallinity index in the loess-paleosol, which can be used as an indicator of the circulation intensity of the East Asian summer monsoon.