云南毛坪铅锌（银、锗）矿床流体包裹体特征及成矿流体来源

云南毛坪铅锌(银、锗)矿床是川滇黔成矿域滇东北地区以碳酸盐岩为主岩的中-大型铅锌(银)矿床的典型代表。矿体空间分布严格受 NE 向层间断裂带和猫猫山倒转背斜的控制。主要脉石矿物(铁方解石、方解石及白云岩)中的流体包裹体发育,一般较小(3～15μm),主要为纯液相和液相包裹体,常沿矿物结晶面密集成群展布。成矿流体属 Na~ -K~ -Ca~(2 )-CI~- -F~- 型,流体包裹体均一温度为180～218(C,盐度为4.1 wt%～9.5 wt% NaCl,成矿压力为406×10~5～570×10~5Pa。在主要脉石矿物流体包裹体中,Na~ /K~ (1.54～4.53)与 Cl~-/F~-(0.72～156.33)较高,而重晶石流体包裹体中 Na~ /K~ (0.32～8.36)与 Cl~-/F~-(1.06～16.77)较低。成矿流体的(D 为-23‰～-64‰,方铅矿、闪锌矿和黄铁矿中流体包体(~(18)O_(v-SMOW)依次为0.3‰～6.2‰,-9.0‰～3.4‰和-6.8‰～-12.7‰。脉石矿物的(~(13)C_(v-PDB)为-1.1‰～-3.7‰。以上信息更好地揭示了成矿流体是变质水、岩浆水和建造水混合的产物,它们与沉积作用、昆阳群基底的变质作用及岩浆热液作用有关。该矿床本身可能是富含铅、锌、银等成矿流体对流循环沿构造"贯入"而成。该矿床不同于典型的 MVT 型铅锌矿床,是一碳酸盐岩为主岩的铅锌多金属硫化物矿床。

Features of fluid inclusions and sources of ore-forming fluid in the Maoping carbonate-hosted Zn-Pb-( Ag-Ge) deposit, Yunnan, China

The Maoping Zn-Pb-(Ag-Ge) deposit is an important representative of the medium-to large-sized carbonate-hosted Zn-Pb-(Ag) deposits in northeast Yunnan, occurring in the Sichuan-Yunnan-Guizhou Zn-Pb Ore-forming Zone. The spatial distribution of ore bodies were controlled by the NE-extending interstratified fault belts and inverted Maomaoshan fold. Generally, fluid inclusions within the major gangue minerals, as ferro-calcite, calcite and dolomite are dominated by two kinds of small inclusions (3～15 μm) including pure-liquid and liquid. The inclusions exist in concentrated groups along the crystal planes of the gangue minerals. The ore-forming fluids belong to the Na+ -K+ -Ca2+ -Cl- -F - type, are characterized by temperatures of 180 ～ 218 ℃, medium salinity in 4. 1 wt% ～ 9.5wt% NaCl, and medium pressure at 406×105～570×105 Pa. The ratios of Na+/K+ (1.54～4.53 ) and Cl-/F- (0.72 ～ 156.33 ) in the fluid inclusions of gangue minerals are relatively high, while those of Na+/K+ (0. 32 ～ 8.36 ) and Cl-/F- (1.06 ～ 16.77) in the inclusions of barite are relatively low. The waters of fluid inclusions have δD values from -23‰ to -64‰. The δ18OV.SMOWvalues of the ore-forming fluids range from 0. 3‰ to 6.2‰ for galena, -9.0‰ to 3.4‰ for sphalerite, and -6.8‰ to -12.7‰ for pyrite. δ13CV-PDBvalues range from -1.1 to -3.7 for gangue minerals. These data better demonstrate that the ore-forming fluids were the compositing results of the magma water, metamorphic water and hosted water, and mainly derived from magmatic hot fluid and hosted formation water, in relation to the sedimentation, the metamorphism of the Kunyang Group in the basement and magmatic hydrothermalism. The deposit itself might have resulted from ascending cycles along metallogenic structures of ore-forming fluid, enriched in Pb, Zn and Ag. The deposit is related to carbonate-hosted Zn-Pb sulphides.