Prospecting Study On Off-Shore Diamond Placer In The Fuzhou Bay,South Liaoning

Diamond is an important non-metallic mineral resource which has great industrial and economical values.Diamond deposits can be classified into original and secondary placer.The annual output of diamond in China is less than 1%of the world's annual production.The proved reserves in China are mainly distributed in Liaoning,Hunan and Shandong Provinces.The Wafangdian is one of the main producing areas in China.There are many kimberlite primary deposit,only 3 small and medium diamond placer near the primary deposit.The erosion of diamond is enormous after the age of kimberlites intruding into the surrounding rocks in Late Ordovician.On the basis of previous work,the source of diamond placers is studied combining the material sources,hydrology,neotectonics.In addition,the factors of mineral characteristics of garnet from the bottom samples and the high-resolution sub-bottom profiles of Fuzhou bay are discussed in the paper.Finally,the possibility of diamond placers existing in Fuzhou bay,the west of Wafangdian is presented.The main contents and results in this paper are as followings:(1)228 million carat of diamond was erosion after the age of kimberlites intruding into the surrounding rocks in Late Ordovician,and was transported to the west by Fuzhou River.(2)The almandine in bottom sediments from Fuzhou Bay was proved as similar as the garnet from eclogite xenoliths in kimberlites,which indicated the possibility of diamond placers existing.(3)Sedimentary units were confirmed by high-resolution sub-bottom profile.Three seismic reflection interfaces(T0,T1,T2)were found under Fuzhou Bay,and we get a preliminary knowledge of morphology species and distribution characteristics.Above all we recognize a river wriggle from north to south in the mouth of Fuzhou River.(4)According to the analysis above we confirmed three areas as enrichment region of diamond placer,where are the mouth of river and the underwater groove.