Study On Rock Alteration Of Porphyry Molybdenum Copper Deposit Of The Bangpu, Tibet

The Bangpu Mo-Cu polymetallic deposit is one of the typical large-scaled porphyry deposit,lies in eastern Gangdese metallogenic belt,Tibet.Molybdenum and Copper ore body mainly occur in the porphyry monzogranite K silicified zone, phyllic zone and the outer contact zone with an angular rock of the main shaft .Its shape likes the porphyry such as cystic and irregular shape. Monzogranite porphyry is ore rock itself, Central deposit was Full mineralization. in the south area of deposit is the body of lead-zinc mining, mainly occur in the Luobadui Formation in Lower Permian(P₁l),nearly the edges of F₁ Fault belt's limestone and marble .The structure of ore are impregnation,string ,crumb and breccoated structure et al.The main testure are self-crystals to semi-self crystals,xenotopic,inclusion and coterminal texture et al.Dominanent metallic minerals are pyrite,molybdenum, copper,galena,secondary are sphalerite, borite, magnetite, kibdelophane , chalcocite, et al.We divided the metallogenic process of Bangpu deposit into three stage,which are magma-advanced atage,hydrotherm ore forming stage and supergene stage.When it terms to hydrotherm ore forming stage,we partitioning it to three period also,which are Mo-Cu sulfide period ,Pb-Zn period and gypsum-calcspar period.Mining alteration zoning follows the order of the distribution ring, from the inside to the out side with the order of the Si-Se (silica - sericite zone), Se (sericite zone), Se-Ka (sericite - clay of the band), P (green plate rocks of the zone). Molybdenum ore bodies occur in the western monzogranite porphyry (ηγπ6¹) which mainly occurs in the Si sub-belt -Se (silica - sericite zone) and Se-Ka (sericite - clay of the zone) . Molybdenum at depth was obviously better than the shallow, which shape is vein.Copper orebodies mainly occur in the monzogranite porphyry (ηγπ6¹) which mainly occurs mainly occurs in sub-Se -Ka (sericite - clay of the band) and P (blue plate rocks of the belt). In the deep, copper was obviously better than the shallow, ,which shape is vein. Ore is mainly and Evenly in monzogranite porphyry (ηγπ6¹), angular rock (hs) and gabbro Green Rock (βv),which mainly occur in Se (sericite zone) and P (blue plate rocks of the belt).