PRELIMINARY STUDY ON SEDIMENTARY FEATURES OF RADIAL SAND BAR OF NORTHERN JIANGSU FROM ANALYSIS OF CLAY MINERALS CHARACTERISTICS
Zhao Quanji ( First Institute of Oceanography, National Bureau of Oceanography )
On the basis of the analysis, identification and estimation of the clay minerals of northern Jiangsu, this paper deals with a more detailed analysis of the characteristics of the contents and combinations of the clay minerals. According to the morphology of thereflecting peaks of the X-ray diffraction spectrum pattern of the clay minerals,the difference in intensity and the distribution of the peak heights at 7A, 10A and 14A in the triangular diagram, the surficial clay minerals in that region may be subdivided into three regions, namely: the region of the underwater delta of the ancient Huanghe River ( Ⅰ ) , the radial sand bar region ( Ⅱ) , and the region of the north side of the Changjiang River mouth ( Ⅲ) . In constrast with the clay mineral characteristics of the coastal land and rivers,it is found that the sediments of region ( Ⅰ) were mainly affected by the ancient Huanghe River, those of region (Ⅲ) mainly came from the Changjiang River,and those of region (Ⅱ) were a mixture of the sediments of the ancient Huanghe River and the Changjiang River in its early stage. According to the analysis of the correlation data on grain size, heavy minerals, chemistry, spores and pollen, and ancient microorganisms, the distributional characteristics of the clay minerals have been further verified and supplemented. After the contrast is made between the distributional characteristics of the clay minerals and the data on suspended substances,salinity, hydrodynamics and submarine relief, it has been shown that the movement and spreading conditions of the sediments of this region are controlled by the hydrodynamic conditions. This has been also verified by satellite images. Thus,the clay mineral characteristics play an important role in the study of the sedimentary features.