| Duobuza copper deposit is located100kilometers north-west of the Gaizecountry, Tibet. Located at binding site of the southern margin of the Qiangtang plateand western part of Bangong-Nujiang suture zone, duobuza tectonic magmatic arc.The hosting strata is second section of Lower Jurassic Quse Formation. Formationtendency to overall in the south west, moderate dip. Fault structures within the miningarea development, pluton and mineralization controlled by faults. mining area rockmass granodiorite porphyry in the main, closely related to the deposit, with SHRIMPzircon U-Pb age results are121.6Ma±1.9Ma(Li Jingxiang et al,2008),120.9±2.4Ma(She Hongquan et al,2009), Molybdenite Re-Os model ages range from117.6±1.3~118.5±1.4Ma, isochron age of118.0±1.5Ma (She Hongquan,2009).Through the observation of geological phenomena, collecting rock and oresamples, Identification of minerals under the microscope and inclusion test analysis,combined with scanning electron microscopy, energy spectrum component analysis,research the tectonic and structure of the ore, and the type of ore mineral and ganguemineral. Major tectonic in the deposit are hydrothermal packing action andmetasomatism, followed by clastation and tectonic stress.through the identification,there are22kinds of ore minerals in the deposit, mainly in sulphide minerals,followed by metal oxides.By microscopic identification the fluid inclusions in quartz veins, which formedin magmatic hydrothermal period, quartz sulfide stage. Fluid inclusions are dividedinto pure liquid-phase inclusions, gas-liquid two-phase inclusions, gas-liquid-solidthree-phase inclusions. By homogenization temperature and salinity tests of primaryinclusions, and calculated the salinity and density. Through the test, show thathomogenization temperature get a wide range, dominated by range of340℃to450℃,inclusions salinity range of30.64%to57.07%, average41%,shows the characteristicsof high salinity. Inclusions pressure range of10~135×105Pa, density range of1.07~1.13g/cm3,which are high density fluids.According ore fabrics, mineral type and mineral assemblages relationship,Duobuza copper deposits can be divided into two mineralization periods and five mineralization stages: magmatic hydrothermal periods and supergene weatheringperiods, which magmatic hydrothermal periods can be subdivided into five stages.Granodiorite porphyry intrusion and mineralization process can be summarizedas: late Jurassic to early cretaceous, new Tethyan oceanic crust subducted intocontinental margins, which carried large amounts of metallogenic material, moltenmetasomatism mantle wedge and lower crust, formed into a metallogenic materialrich andesitic magma. Magma along deep faults rising to upper crust, along secondaryfaults F2intrusion into Lower Jurassic Quse Formation metamorphic feldspar quartzsandstone. A large number of post-magmatic hydrothermal, which formed by magmacooling and crystallization, extraction metallogenic material from magma andsurrounding rock, Filling in the rock and rock fissures. As the temperature and thepressure decreases, from rock mass to surrounding rock, sequentially formed potassicalteration, quartz sericitization propylitization alteration zonation. Meanwhile metallicminerals precipitate from hydrothermal, different mineral assemblages formed indifferent alteration zones, deposit formed. After mineralization period, due to theactivities of fault structure, played a certain role in damage to the ore body. |
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