Geological Characteristics And Identification Of Metallogenetic Rocks For The Zhunuo Porphyry Cu Deposit In The Gandese Belt

The Zhunuo porphyry Cu deposit is located at the southern of Gangdese-Nyainqentanglha compound magmatic arc, west of Gangdise porphyry copper metallogenic belt. Now the deposit is step into general exploration stage, but the metallogenetic is not sure. As the prerequisite, we have foud out the ore deposit geological characteristics. The research methods to identify the metallogenic rock include:Analysis of the geology charactersitcs, compare fluid inclusion in quartz phenocryst of different rocks, and the method on genetic mineralogy.The types of rock is complicated in this area, vlcanic or subvolcanic include rhyolitic porphyry, quartz porphyry, aplite, crystal tuff and dacite; intrusive rocks include porphyritic biotite monzonitic granite and monzonitic granite porphyry; dikes include granite porphyry, quartz syenite porphyry, diotitic dikes and lamprophyre. The east plate of nearly NS-trending have descended relative to west plate, so the eastern mining area still exist prospecting potential. The main ore body like a irregular ellipses in palne, a thick plate in section. The main texture of ore is Veinlet disseminated. In the mining area, there are exsit two sets of alteration systems, around the porphyritic biotite monzonitic granite from inter to outside are potassium zone, quartz-sericite zone and propylitization zone successively, while around the monzonitic granite porphyry is potassium zone and quartz-sericite zone successively. The vein can divided into three category, type A at the early mineralization stage, type at transform stage, type D at the late mineralization stage, and the main ore-forming time is corresponding to the late stage of type A vein and the hole stage of type B vein.By analysis of the ore geology features, the age of porphyritic biotite monzonitic granite and monzonitic granite porphyry were foud out to the most close to metallogenic age. The main orc body occurrences in monzonitic granite porphyry mainly. Both porphyritic biotite monzonitic granite and monzonitic granite porphyry have developed indepent The alteration system, the later’s alteration ability is morw stonger and time of formation is A little later. Both porphyritic biotite monzonitic granite and monzonitic granite porphyry have developed the vein of tye A, B and D, and the later have developed more veins of tye A. the fluid inclusion study indicated that both porphyritic biotite monzonitic granite and monzonitic granite porphyry have developed high salinity aqueous solution fluid inclusion with halite, the later even have developed high fluid inclusion with hematite in quartz phenocryst, sugest the early fluid are high oxygen fugacity, however the fluid inclusion in the other rocks’quartz phenocryst are control by distance from the core of ore body, or not developed, or be distortured. According to the above, Both porphyritic biotite monzonitic granite and monzonitic granite porphyry have the genetic relationships with mineralization, and the ralaitonships with monzonitic granite porphyry are more close. The father study on genetic mineralogy, show monzonitic granite porphyry have rich content of water, high oxygen fugacity, and rich content of sulfur, this are like to the Typical porphyry copper deposits’ metallogenic rock in globle wold.In clusion, the metallogenetic rock in the Zhunuo deposit shoud be monzonitic granit porphy, and the porphyritic biotite monzonitic granite also have some genetic relationships with minerlation so that can be as a precursor rock of mineralization.