Characteristics and significance of the fluid inclusions and stable isotopes from the Nanyangtian scheelite deposit in Malipo, Yunnan
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摘要: 对南秧田层状矽卡岩型白钨矿石中石榴石及电气石石英脉型白钨矿石中石英流体包裹体岩相学特征研究表明,与成矿有关的包裹体主要有富液相、富气相和含子晶的流体包裹体3种类型。矽卡岩型矿石中石榴石及共生石英的包裹体均一温度为128~250℃,盐度w(NaCl)=0.7%~8.1%;电气石石英脉型白钨矿石中石英的流体包裹体均一温度范围为181~325℃,盐度w(NaCl)=1.57%~15.76%。两种类型矿石成矿溶液密度为0.75~0.95g/cm3,表明形成这两种类型矿石的成矿流体均属于中温、中-低盐度、低密度的流体。氢氧同位素结果显示其主要来源于地层水(变质水),后期受到了岩浆水的叠加改造作用。硫同位素落入沉积岩、变质岩及蒸发硫酸盐的硫同位素组成范围内。Abstract: The petrographic examination of the fluid inclusions in quartz from the garnet-tourmaline quartz vein-type scheelite ores from the Nanyangtian stratified skarn-type scheelite deposit in Malipo, Yunnan shows that the inclusions related to the mineralization consist of liquid-rich, gas-rich and daughter crystals-bearing fluid inclusions. The homogenization temperatures of the inclusions in garnet and quartz from the skarn-type ores range between 128℃ and 250℃, and the salinities between 0.7% and 8.1%. The homogenization temperatures of the fluid inclusions in quartz from the tourmaline quartz vein-type scheelite ores range between 181℃ and 325℃, and the salinities between 1.57% and 15.76%. The densities of 0.75 to 0.95 g/cm3 for the ore-forming solutions suggest the mesothermal, medium-to low-salinity and low-density ore-forming fluids for the above-mentioned ores. The hydrogen and oxygen isotope determinations indicate that these ore-forming fluids originated from the formation water (metamorphic water), which was subjected to later mixing and modification by magmatic water. The sulfur isotope values for the Nanyangtian scheelite deposit fall into the sulfur isotopic fields of the sedimentary rocks, metamorphic rocks and evaporate sulfates. It can be seen that the Nanyangtian scheelite deposit may be assigned to the sedimentary-metamorphic skarn-type deposit rather than the classifical skarn-type deposit.
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Keywords:
- Nanyangtian /
- fluid inclusion /
- garnet /
- quartz /
- hydrogen and oxygen isotopes /
- sulfur isotope
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