GEOCHEMICAL CHARACTERISTICS OF THE SURFACE SEDIMENTS IN THE MUD AREA OF THE YANGTZE ESTUARY

The X ray fluorescence spectrometry was used to make a geochemical analysis of 20 major and trace elements (SiO₂、Al₂O₃、TFe₂O₃、MgO、CaO、K₂O、Na₂O、MnO、TiO₂、P₂O₅、Cu、Pb、Ba、Sr、V、Zn、Co、Ni、Cr、Zr) for 105 surface sediment samples taken from the mud area of the Yangtze Estuary. The statistic features and distribution patterns of all the 20 elements in the study area were discussed, and the system cluster analysis was carried out for element geochemical division. The results show that the study area can be classified into three geochemical provinces. The Province Ⅰis characterized by comparative concentration of SiO₂、Na₂O、Zr,and depletion of Cu, in the western part of the study area;The Province Ⅱis located in the middle of the study area, which is rich in Al₂O₃、Fe₂O₃、MgO、Cu;The Province Ⅲ, which lies in the east part of the study area, has similar geochemical characteristics with Province Ⅰexcept for the special enrichment of CaO and Sr. The result from geochemical division and factor analysis suggests that grain size is the most important factor controlling the distribution of major and trace elements in the study area. Biogenic substance,provenance and authigenous minerals can also influence the distribution of some particular elements, such as CaO, Sr, TiO₂.