Vertical Zoning And Mineral Prospecting Method Study On Nanjiaohe Silver-polymetallic Deposit

Nanjiaohe silver-polymetallic deposit includes Ag, Pb, Zn, Cu, Au etc. mineralization. Some metal's reserves already approaches middle scale, it has a important economic value. The deposit locates in the contact belt of granite and Lancang group. This deposit possesses a clear vertical zoning, it is a new type Lead-Zinc mine in Yunnan province. In this geology district there is a very good foreground of exploration. The writer began a first study on this ore deposit combined the field geological survey and analytical data in the laboratory. This paper has studied regional geology background, characteristic of Lead-Zinc deposits in Yunnan province, also studied ore deposit, geochemistry, vertical zoning, inclusion, prospecting foreground and accomplished geophysicl exploration experiment in Nanjiaohe. Acquired the following conclusions: Nanjiaohe ore deposit locates in south of Sanjiang region, here the geological structure is complex, tectonomagma moved continually, happened strong metamophism, all these provided a good precondition for ore formation. East of the deposit is the famous Lincang-Menghai batholithic granite formed during Varisn to Indo-Chinese epoch which has a north-south direction of strike, west is Lancang grouup metamorphic rock. The ore body is located in the fractured zone between granite and metamorphic rock. Mineralization processing was related to the atmospheric water and gmitic magmatism. Ore body was mainly contrled by the fractured zone, metallogenetic elments migrated and allocated in the zone too. Ore body occurred in veins. Metallization has a clear vertical zoning, underside is Pb, Zn, central section is Pb, Zn, Ag, Au and upside is Sb. Laydown zoning is the mainly facter, geyser zoning affected little. Metallization occurred in rock alteration, the alteration types are silication, seritization, pyritization and carbonation etc. Rock alteration is a good criteria for ore prospecting. Through the study of isotope we get the information that metallogenetic elements mostly came from strata of Lancang group, ore fluid mainly came from atmospherics water, mixed a small amount of magmatic solution. Granite is S-type, in the mineralizing process it offered energy helped the formation and migration of ore fluid. After the study of inclusion, we found that fluid was low salinity, low denseness and low temperature. The decline of temperature, pressure and pH was mainly factor that ore elements laied down from fluid. Mineralizing fluid migrated, concentrated and allocated in the fractured zone between granite and metamorphic rock, it was a good canal for Rn, U, Tb and K, added intense sericitization, in geophysical exploration we found that y -ray spectrometry, Radon spectrometry can reflect the allocation of fractured zone, X-ray fluorescence analysis in laboratory can effectively find alteration envelope, elements geochemical abnormality, soil primary and secondary halo, then find deposits allocation. Electric prospecting can be used to find concealed sulfide body in target area. According to the study result, a metallogenic model is presented corresponding with the prospecting model and norms.