新疆哈密小白石头钨钼矿床流体包裹体及矿床成因
Fluid Inclusions Constraints on the Origin of the Xiaobaishitou W-Mo Deposit in Hami, Xinjiang, NW China

新疆哈密小白石头钨钼矿床位于中天山地块，是北疆代表性的钨钼矿床，但人们对其成矿流体性质和矿床成因类型了解得很少.矿床地质研究表明，矿体主要产于三叠纪黑云母花岗岩与蓟县系卡瓦布拉克群碳酸盐岩接触带，根据穿插关系和矿物组合，成矿阶段可划分为干矽卡岩、湿矽卡岩、氧化物、硫化物和碳酸盐5个阶段，白钨矿和辉钼矿分别形成于氧化物和硫化物阶段.流体包裹体显微测温结果表明，成矿早期(干矽卡岩阶段)流体为中高温、中高盐度的NaCl-H2O-CO2体系，成矿晚期(碳酸盐阶段)演变为低温、低盐度的NaCl-H2O体系.小白石头矿床为矽卡岩型钨钼矿床，流体包裹体特征指示流体混合及降温可能是矿质沉淀的主要机制.
The Xiaobaishitou W-Mo deposit is one of the typical W-Mo deposits in North Xinjiang, located in the eastern Tianshan Orogen. The ore body mainly occurs in the contact zone between Triassic biotite granite and crystalline limestone of the Mesoproterozoic Kawabulag Group. However, the characteristics of metallogenic fluid and genetic type of the Xiaobaishitou deposit remain relatively unclear. Based on the ore textures, structures and mineral assemblages observed, it is inferred that the deposit has been formed in a fivestage hydrothermal process, namely dry skarn, wet skarn, oxide, sulfide and carbonate stages. Scheelite and molybdenite occurred in oxide and sulfide stages, respectively. Microthermometric data show that the ore fluid system evolved from CO2rich, probably magmatic hydrothermal to CO2poor, meteoric fluid. The microthermometric results also suggest that metal precipitation resulted from fluid mixing and cooling. Here we propose that the Xiaobaishitou W-Mo deposit may be a skarn mineral system