Abstract:

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