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对长江中游南岸鄱阳湖东侧砂山下风向的太平关黄土剖面进行了粒度测试分析,与南京下蜀黄土、巫山黄土和长江河流沉积物进行了对比。结果表明:1)太平关剖面粉砂(5-50μm)含量达到了50%以上,粘土次之,砂的含量略大,但不足10%,风成“基本粒组”比重较大。太平关剖面的粒度参数与风成黄土的典型剖面基本一致,而和长江河流沉积物差别明显,表明太平关剖面的风成属性;2)结合区域的气候特征及其粉尘动力学原理,太平关剖面不可能与北方黄土一样来自于西北荒漠、戈壁,而是在冰期的裸露的长江河漫滩、谷地伴随着强大的冬季风经过重力分选近距离搬运的结果;3)粒度组分深度变化揭示多旋回的黄土-古土壤特征,黄土对应的粘土组分含量较大,粉砂和砂的含量较小,古土壤层位对应的粘土组分含量较小,粉砂和砂的含量较大,这种“沉积-成土”的韵律性变化佐证了更新世以来的冷暖气候波动。
Particle size analysis of the Taipingguan loess profile in the downwind direction of the Poyang Lake in the south of Poyang Lake in the middle reaches of the Yangtze River was carried out, and compared with the Xiashu loess, Wushan loess and Yangtze River sediments in Nanjing. The results show that: 1) the content of silt (5-50μm) in Taipingguan section reaches more than 50%, the clay is second, the content of sand is slightly larger, but less than 10%, and the proportion of aeolian “basic granule” is larger. The grain size parameters of the Taipingsu section are basically the same as the typical sections of the aeolian loess, while the sediments of the Taipingguan section are obviously different from each other, indicating the aeolian properties of Taipingguan section. 2) Combining with the climatic characteristics of the region and its dust dynamics, Taipingguan The section can not come from the northwest desert and the Gobi as the northern loess, but the bare Yangtze River floodplain during the ice age. The valley is accompanied by the strong winter monsoon by gravitational sorting. Cyclical loess - paleo-soil characteristics, the clay content of loess corresponds to a larger content of silt and sand smaller, paleosol layer corresponding to the clay content of small, silt and sand content, which The rhythmic variation of species “sediment-soil” corroborates the warm and cold climate fluctuations since the Pleistocene.