SURFACE-TEXTURAL ANALYSIS OF SOME HEAVY MINERALS FROM SOUTHERN YELLOW SEA
Zhao Zhenqing (Institute of Marine Geology, Ministry of Geology & Mineral Resources, Qingdao, China, 266071)
Heavy minerals have a low abundance but widespread in sediments, and their source rocks are also widely distributed. Every grain of heavy minerals has been affected by physical and chemical changes in the environment and has marks of the changes left on the surface. Therefore, studying the surface textures of heavy minerals has very important significance to the reconstruction of environment in which the sediments formed. In this paper, surface textures of tourmaline, garnet, apatite and sphene in shallow sediments of southern Yellow Sea are studied under scanning electronic microscope, thus providing a basis for the work. Surface textures of heavy minerals can be seen in shape and in mechanical and chemical features. Mechanical features include conchoidal fracture, impact step, pit and V-shaped pit. Chemical features include solution hole and pit,V-shaped solution pit, stepped solution groove and chemical precipitation. In studing surface textures, it is more suitable to use tourmaline and garnet than apatite and sphene. Surface texture features of tourmaline and garnet in shallow sediments of the southern Yellow Sea are somewhat different according to fluvial-tidal flat-neritic-tidal sand ridge environments.