The Alteration And Mineralization Characteristics And Geochemsitry Of Primary Halos Of Porphyry Molybdenum (Copper) Deposit Of Tongcun In Kaihua County Of Zhejiang Province

Molybdenum (copper) deposit of Tongcun located in Kaihua Town of Quzhou City in Zhejiang Province, geotectonically is situated in the southwest of Qiantang synclinorium adjacent to Jiangnantai anticline, and lies in Qinzhou-Qiantang juncture zone. The juncture zone is one of the important polymetallic ore areas in our country, including well known Tongchang, Jinshan and Yinshan deposits in which molybdenum reserves accounted for 4.10% in endogenic molybdenum of countrywide situated 5th.Strata are exposed mainly Changwu Formation of Ordovician in the study area, the main directions of fault include northeast, north-northeast, northwest and east-west, and rock types contain altered granite porphyry and altered monzonitic granite. The mine area consists of five ore blocks, including Songjiazhuang, Jiangjunwu, Huashandi, Dayutang and Huangbaikeng, in which Songjiazhuang ore block has a better mineralization and the paper addressed this ore block much.The research got some conclusions as follows: 1) the alteration zone of the mine area is composed of potassic, sericitization and argillization from the center of the rock mass outwards, in which the sericitization is mainly alteration type and has more developed quartz veins with 4 to 6 per meter; 2) the metallogenesis of Tongcun molybdenum porphyry deposit is divided in two periods and six stages as follows: liquid sulfide period including early skarn stage, late skarn stage, molybdenum-potassic stage, quartz-sericite-sulfide stage, molybdenum-quartz vein stage and quartz-carbonate stage, and supergene period; 3) the mine area has an intense enrichment of Cu, Mo and W metal, in which the copper content is 163 times than the one in Jurassic magmatic rock of Zhejiang western, and the molybdenum content is 124 times, tungsten is 40 times; 4) according to the improved Gregorian's zoning index method, the axial zoning sequence of No.0 exploration profile from ZK007, ZK008 and ZK009 to ZK010 is Mn-Sb- As-Hg-Au-Mo -Zn-Pb -Cu -W-Ag-Bi; 5) based on profile characteristic of metallogenic element in the mine area, the contents of Cu, Mo and associated elements increase with depth, and multiplicative ratio of surrounding elements of deposit (such as Cu, Pb and Zn) and trailing elements(W, Sn and Mo) indicates that there may be a concealed ore body in 500 to 600 m depth at southeast of No.0 exploration line in the mine area; 6) factorial and cluster analysis results of metallogenic and associated elements of 4 drill holes in the mine area are in accordance with the division of the metallogenesis progress.Finally, the geological and geochemical prospecting model of Tongcun molybdenum (copper) deposit is set up on the basis of comprehensive research of mining geology, distribution and zoning characteristic of anomalous elements of the deposit and geochemical prospecting index for further ore-prospecting of this area.