共生黑钨矿与石英中流体包裹体红外显微对比研究——以瑶岗仙石英脉型钨矿床为例

利用红外显微镜对湖南瑶岗仙石英脉型黑钨矿矿床中共生的黑钨矿与石英原生流体包裹体均一温度和冰点的测定结果表明,石英中流体包裹体均一温度范围为149～352℃,主要集中在160～300℃之间,盐度w(NaCleq)为0.9%～9.5%;黑钨矿中流体包裹体均一温度范围为212～386℃,主要集中在280～360℃之间,盐度w(NaCleq)为4.5%～15.2%.可见,黑钨矿中流体包裹体具有更高的均一温度和盐度,与石英中原生流体包裹体均一温度相差可达60℃,盐度w(NaCleq)相差可达6%.结合该矿床的矿石显微结构特征、包裹体岩相学特征及前人所做的氢、氧同位素测试分析结果,推断黑钨矿主要形成于早期阶段,为均一流体冷却成因,石英形成较晚,主要为流体混合成因.

An infrared microscope investigation of fluid inclusions in coexisting quartz and wolframite: A case study of Yaogangxian quartz-vein wolframite deposit

In order to understand the differences between the fluid inclusions in ore minerals and those in gangue mine-rals, the authors performed a microthermometric study of fluid inclusions in wolframite and coexisting quartz from the Yaogangxian quartz-vein wolframite deposit by using infrared microscopy. The results show that homo-geneous temperature (t_h) and salinity of fluid inclusions in quartz are obviously different from those in wol-framite, in spite of the fact that these two minerals were formed at the same ore-forming stage. The data show that the homogeneous temperatures of fluid inclusions in quartz are 149 ～ 352℃, mainly concentrated in the range of 160～300℃, and the salinities are 0.9%～9.5% ; whereas the homogeneous temperatures of fluid in-elnsions in wolframite are 212 ～ 386℃, concentrated at 280 ～ 360℃, and the salinities are 4.5 % ～ 15.2%.Thus, the fluid inclusions in the quartz have lower homogeneous temperature and salinity than those in wol-framite. The differences of homogeneous temperatures between wolframite and quartz can reach 60℃ and those of salinities can reach 6 %. Combined with H, O isotope analyses and ore micro-texture features, the authors have drawn a conclusion that the fluids captured in wolframite were formed at an early stage when the solution was homogeneous, and the temperature declining was the main cause for mineral deposition, whereas the fluids in quartz had mixed fluid properties of igneous fluid and underground water, suggesting their formation at a later stage.