Abstract：By the subject named environmental geology survey and evaluation on the national typical coastal water areas, the authors analyzed the surface sediments, the types and distribution of sediments geomorphology in typical coastal water areas shallower than 20 m, Guangxi. And the content of detrital minerals, and their types distribution, variation and combination were studied on this basis. The results show that there are strong hydrodynamic and various ways of current influence on the study areas. And there are nearly 30 types of detrital minerals mainly including quartz, feldspar, ilmenite, mica, zircon, pyrite and glauconite, and rich in heavy minerals. Since the transgression during Early Holocene, the study areas evolved into the depositional environment of shallow-sea bays. And the types of detrital minerals are similar with those before, but their content is different, which is due to climate change and sea-level fluctuation. The types and content of detrital minerals, especially heavy minerals, in the study areas are different in different geological units, which are divided by surface sediments’ and geomorphic types. Heavy minerals combination have 2-3 sub-divisions in these study areas. And these sub-divisions and depositional environment are closely related. The results show that detrital minerals mainly originate from the weathering in onshore area, coastal erosion and river carrying, which indicates that detrital minerals are terrigenous.
2017, Vol. 4 
