| Duo-long ore concentration area located in Ngari prefecture of Tibet autonomous region Gaize 100 km north-west of the county, in the hinterland of the Qinghai-Tibet plateau Bangong-Nujiang metallogenic belt western part of the tectonic position in which the south Qiangtang southern edge of the southern Qiangtang depression belt. The strata are mainly riganpeicuo group ofthe Triassic system, Quse group of Jurassic,Sewa group, Cretaceous lower Meiriqiecuo group, Palaeogene Kangtuo group and Quatemary. There are lots of faults in this area. The fragile structure control the rock mass and mineralization.Duobuza and Bolong mining rock types include granodiorite porphyry, granite, corcovadite, quartz porphyry, tonalite and diabase. Granodiorite porphyry rock is apophysisal, stock. The colour of rock is light gray, and has porphyritic texture, massive structure. It includes quartz, plagioclase, and a little of biotite. The groundmass includes quartz, feldspar, biotite and opaque mineral. Matrix plagioclase feldspar-based, with small amounts of alkali feldspar, occurred sericitization. Porphyry rock mining is not exposed on the surface. According to speculate rock drilling data was plate. Granodiorite porphyry and granite porphyry host rocks mainly lower Jurassic Quse formationThrough chemical analysis of rocks means that Duobuza and Bolong mining area the whole rocks show uniform major element compositions, with SiO2 average contents of 64.05%, and(Na2O+K2O) average contents of 5.06%, σ=0.46~2.54, AR=1.43~2.70, A/CNK=1.04~2.95, show high potassium and low sodium features, belong to the acid rock, K calc-alkaline-shoshonite series, calc-alkaline series of sub-alkaline rock series with geochemical characteristics of Rb, K rich, but Ba, Nb, Ta, Ti loss. In addition, these rocks with REE patterns right deviation obviously, Eu weak enrichment or without enrich. It shows that the rocks may originate from partial melting of upper crust, without crystal fractionation,lead to lithophile elements enter into magma preferentially, and HFSE have been preserved in the residual solid phase.According to Duobuza and Bolong mining ore rock specimens observed, under an optical microscope and other means of identification, summarized many do not and miscellaneous Bolong rock and wall rock alteration types basically the same. Rock alteration types include K-feldspar, silicification, biotite, sericite-oriented, of clay, plaster of carbonation, epidotization and chlorite and so on. Rock and country rock contact zone of intense alteration, mainly potassium, silicification, chlorite, carbonate and so, by the Rock Center weakened the wall rock alteration degree direction.Mineralization types including thin veins, veinlets- disseminated, mass, disseminated, porphyritic mineralization. Rock and country rock contact zone mineralization strong, wall rock mineralization weak.Ore ingredients are pyrite, chalcopyrite, bornite, molybdenite, magnetite, chalcocite, hematite, rutile, blue chalcocite, covellite, galena, sphalerite, selenium and silver, goethite, lepidocrocite and the like; the main vein structure ore- stockwork structure, disseminated structure and mottled structure, a film-like structure, gelatinous structure, porous structure and the like. The main ore structure crystalline structure, account structure, solid solution separation structure and stress structures.By analyzing the geochemical characteristics of the ore-bearing rock that belongs to the S-type granite rock area; mineralization is closely related to the granodiorite porphyry LA-ICP-MS zircon U-Pb ages around 120Ma(Li Jinxiang, 2008; She Hongquan, 2009; Chen Huaan et al., 2013), intruded era Yanshan late magmatism overall area can be divided into three phases: the granodiorite porphyry ore-excluding mining granodiorite porphyry- mafic volcanic rocks; molybdenite Re-Os isochron age of 119Ma(She Hongquan, 2009; Zhu Xiangping et al., 2011) or so, on behalf of the quartz- molybdenite phase formation age of molybdenite.Comprehensive analysis Dolong ore rock ore concentration area formed in the late Jurassic- early Cretaceous period continental margin arc environment of active continental margin. Magma from the subduction under the crustal rocks by baking hot mantle magma molten lava formed part occurrence, magma rises along the tectonic fissures formed after the emplacement of the ore-bearing rock condensation. |
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