赣北鄱阳湖地区黄土元素地球化学特征研究

对长江中下游彭泽定山-太平地区黄土进行元素分析，并将结果与黄土高原黄土、长江下游等地典型风成堆积进行对比。结果表明：（1）赣北鄱阳湖地区黄土元素P、Na、Ca亏损明显，Ti、Fe等为残留富集；断面上黄土脱Ca、Na过程明显，正朝着脱K去Si富Al趋势发展；元素变化率特征，赣北鄱阳湖地区黄土主要元素的迁移顺序如下：Ca>P>Na>Mg>Mn>K>Si>Al>Fe3+>Ti。（2）赣北鄱阳湖地区黄土风化强度属于中等风化强度，与其他地区风成沉积在风化强度由弱到强上构成如下序列：〖JP2〗洛川黄土<镇江黄土<赣北鄱阳湖地区黄土<宣城风成红土。研究区黄土风化强度略强于镇江黄土，主要是由二者地形条件决定的排水条件造成。（3）研究区稳定元素组成明显区别于其他地区风成沉积，指示定山-太平地区沙山砂、黄土可能来自统一的物源区即其上风向的长江河漫滩平原

THE STUDY OF CHEMICAL WEATHERING INTENSITY IN NORTH POYANG LAKE REGION

Geochemical characteristic of elements is one of the most important features of the aeolian dust deposits. The sediments we analyzed include loess and sandy hill sand in the region of the north Poyang Lake region. The samples were collected by systematic field work and then the major elements were tested. In this paper we analyzed the major element migration features and weathering characteristics of loess in north Poyang Lake region. The results show that: the major elements of loess such as P, Na, Ca, Mg, Mn, P were migrated and leached intensively, while Ti, Fe were slightly rich. The migrating features of major element reveal that the north Poyang Lake region loess have finished the primary process of chemical weathering characterized by leaching of Ca, Na and is undergoing the second process characterized by leaching K, Si and enriching Al. Based on the migrating and leaching rates, the major elements of the north Poyang Lake region loess ranked as follows: Ca>P >Na>Mg>Mn>K>Si>Al>Fe3+>Ti. The north Poyang Lake region loess underwent moderate chemical weathering, because the loess cumulate climate background are relatively warm and moist. The north Poyang Lake region loess intension chemical weathering are slightly stronger than the Nangjing, Zhengjiang loess in same latitude and same time. The difference in geomorphic features leaded to the intensity of chemical weathering of the north Poyang Lake region loess is slightly higher than the loess of the lower reach the Yangtze River. Immobile element of sediments (such as Al and Ti and so on) are very difficult to remove in the weathering process of late. So the feature of stable elements in the sediments can sensationally reflect characteristic of aeolian deposition source area. This method of predicate aeolian deposition source area has achieved conspicuous effect research in northern China loess studies and in North America. In this paper, in order to compare the provenance of sandy hill and loess in the north Poyang Lake region, we analyzed futher the characteristic of proportional immobile elements (Ti, K, Al) of loess and sandy hill sand in the north Poyang Lake region and compared with another aeolian dust deposits located in the lower reaches of the Yangtze River region and the Northern China. The results show that: the immobile elements of sandy hill sand and loess in the north Poyang Lake region indicated their origins from the adjacent floodplains to the north of the Yangtze River. It is a feature of conspicuous area