| 锡铁山铅锌矿床的流体包裹体特征及成矿物理化学条件的初步探讨 |
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| 引用本文：.1985.Fluid inclusion studies of the Xitieshan lead-zinc deposit with a special discussion on physicochemical conditions for ore deposition[J].Mineral Deposits,4(1):22~30 |
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| Fluid inclusion studies of the Xitieshan lead-zinc deposit with a special discussion on physicochemical conditions for ore deposition |
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| Abstract:Ore bodies of the deposit in question occur in Upper Ordovician metamorphosed volcanic-sedimentary rocks. According to the geologic characteristics of these ore bodies, two different mineralization stages could be distinguished, i.e., initial volcanic-sedimentary stage and late superimposed mineralization stage quartz and calcite of these two stages contain four types of fluid inclusion type A, B, C and D inclusions of different stages are quite different in nature. In rocks of initial volcanic-sedimentary stage, no inclusions of type A and B have ever been found and those of type C and D are irregular in shape, minor in quantity and relatively low in homogenization temperature and salinity. In rocks of late superimposed mineralization stage, inclusions are somewhat abundant and are regular in shape, comparatively coarse in granularity and relatively high in homogenization temperature and salinity. Significant variations could be observed in granularity, homogenization temperature, salinity, density and quantities of fluids from the first ore-bearing zone to the third ore-bearing zone or from the rich ore zone to the poor ore zone. Hydrothermal activities were not obvious during the initial volcanic-sedimentary stage but became intense in the late superimposed mineralization stage. Mineralization got increasingly strong with the intensification of hydrothermal activities. Physicochemical conditions responsible for ore deposition seem to have been: (1)ore-forming temperature:110-140℃ for the initial volcanic-sedimentary stage and 180-360℃for the late superimposed mineralization stage,(2)ore-forming pressure:320-360 bar for the late superimposed mineralization stage; (3)weak acid ore-forming environment: pH=5.83 for the late superimposed mineralization stage; (4)salinity of ore-bearing fluids: fluids of the initial volcanic-sedimentary stage were of low salinity(3.2-5.1 wt％ NaCl) whereas those of the late superimposed mineralization stage were of high salinity(32-34.7 wt％NaCl)or moderately high salinity(7.5-11.0 wt％NaCl). Volcanic activities furnished abundant materials for mineralization; sedimentation led to a preliminary concentration of metallic elements; high salinity and high density underground hot brine of late stage also played an important role in ore deposition. |
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