Study On GaYiQiong Copper-lead-zinc Geological Characteristics And Genesis Of Polymetallic Deposit In Baiyu County

Southwest Sanjiang is an important metallogenic belt of nonferrous metals, including copper, silver, gold, lead, zinc, tin and other resources, which has great potential resources. The Area is collectively referred to as "Sanjiang metallogenic belt", but actually contains five tectonic units with significantly differences. From west to east the tectonic units are the Jinsha River mélange Yidun arc belt, Garze-Litangophiolite belt and back-arc basin Ya Jiang fold belt, southwest Shiqu Sanjiang metallogenic belt of the southern section-Garze-Litang area is silver(copper) lead-zinc ore-rich region.As a medium-sized copper,lead-zinc deposit, deposit GaYiQiong goes in less in home and abroad, in addition the degree about this study is in a low level. On the basis of collecting and summarizing the results of previous studies, this research maintally devoted to replenish geochemical data supplement and mineralization is closely related to granite, the precise dating of zircon, mainly in hydrothermal ore mineral trace elements, rare earth elements data and sulfur isotope data and Hf isotopic age data. The application of modern metallogenic theory, the idea of metallogenic geological conditions and ore-controlling factors analysis mineralization, the exploration of the genesis, the establishment of the deposit mineralization mold, the comparison of adjacent Gacun deposit, and focus on the opinion is whether like predecessors described: "whether like Gacun deposit is typical of VMS(volcanogenic massive sulphide) deposits?" through research. Above all comes to the following understanding:Judging from the field observations and phenomena from the microscopic studies, ore veins formed later than late quartz albite porphyry emplacement; quartz albite porphyry body is not only lump late filling, veins- stockwork metallic minerals(chalcopyrite, pyrite, pyrrhotite, sphalerite), but also can see the chalcopyrite, pyrrhotite disseminated a large number of distributed, sphalerite; and ore-forming elements analysis also shows that the rock with a high content of ore-forming elements. This means that the quartz albite porphyry itself carries metallic minerals, and the later deposit vein quartz albite porphyry ore emplacement for after the magmatic(including mine) formed by hydrothermal fluid action.From the analysis of trace elements and rare earth elements, we can find that the source of all the material deposits of metallic minerals are similar, but not the role of the same period of hydrothermal fluids formed, chalcopyrite, galena and late formation formation calcite veins of hydrothermal fluid has a close relationship.From ore sulfur isotope analysis, this paper self-test of eleven and Houzeng Qian(1995) measured thirty-five ?34S sulfides are concentrated around zero, therefore, GaYiQiong sulfide sulfur deposits basically from the deep source of magma.From the petrographic microscope analysis found subvolcanic bodies in the crystallization process condensate formed disseminated sphalerite and late hydrothermal transformation process and the formation of lumps, stockwork chalcopyrite, pyrite, sphalerite, pyrrhotite. From the perspective of science ore illustrate two different mineralization GaYiQiong deposit.Analysis based on test GaYiQiong poor quartz albite porphyry deposit data obtained U-Pb age of the rock mass was 228.5 ± 2.4Ma(MSWD = 0.37)(Chen Xingbing 2015) 1511, quartz albite porphyry samples Age test results for Indosinian. At the same time, GaYiQiong deposit also find a relatively young Himalayan rock, its diorite zircon sample test results show that U-Pb ages of rock was 31.72 ± 0.59Ma(MSWD = 1.4).From Hf isotope test results, quartz albite porphyry substance Indosinian is from the lower crust. Meanwhile Diorite substance derived from the Himalayan depleted mantle, which may be mixed with contaminated material from the lower crust.In summary, GaYiQiong are composed by two poor deposit mineralization which superimposed on the formation of deposits, hydrothermal flow deposits and mineralization occurs first, lead, zinc copper subvolcanic hydrothermal filling and replacement mineralization occurred after the formation of polymetallic deposit; two kinds of mineralization occur at different stages of the same volcanic action, and later to the subvolcanic hydrothermal filling and replacement mineralization as the main mineralization formed by deposits.