西华山钨矿床共生透明矿物与不透明矿物中流体包裹体的对比研究

A comparative study of fluid inclusions from coexisting transparent minerals and opaque minerals in Xihuashan tungsten deposit

西华山钨矿床是一个产于燕山期花岗岩中的大脉型钨矿床。笔者利用红外显微镜、冷热台及其他相关设备对矿床中的透明矿物（石英、绿柱石和萤石）与不透明矿物（黑钨矿、黄铁矿）中的流体包裹体进行了对比研究。结果显示，共生透明矿物与不透明矿物之间，在包裹体均一温度等特征上既可基本相同又可出现很大差异。一般来说，黑钨矿能有效地保存原生流体包裹体（th=300～420℃；晶洞中为220～290℃），仅有少量次生包裹体（th=160～280℃），而与之共生的石英中原生包裹体则几乎被破坏殆尽，现在所见到的包裹体绝大多数是次生的或是在较晚结晶时捕获的（th=130～270℃）。只有未经后期应力作用和流体改造的晶洞水晶及与其共生的黑钨矿，二者获得的结果才相同或相似。绿柱石中通常有大量的次生包裹体和原生包裹体。黑钨矿与绿柱石中硅酸盐熔融包裹体的出现，表明西华山钨矿床的成矿作用始于岩浆一热液过渡阶段，其初始成矿流体是一种岩浆一热液过渡性流体，尔后才演变成单一的热水溶液。笔者认为，在进行金属矿床流体包裹体研究时，应强调共生透明矿物与不透明矿物的对比研究，在进行对比研究时，详尽的基础地质研究和包裹体岩相学观察必不可少；当单独利用透明矿物包裹体资料对金属矿床进行地质解释时，需慎之又慎。

The Xihuashan tungsten deposit, which has a mining history of more than 100 years, is a large vein-type deposit in Yanshanian granite. There exists controversy concerning the metallogenic conditions and ore-forming fluid properties. The fluid inclusions in nine groups of coexisting transparent minerals （quartz, beryl and fluorite） and opaque minerals （wolframite and pyrite） of the Xihuashan tungsten deposit were studied by using infrared microscopy and other related equipment. The data obtained show that characteristics of fluid inclusions in coexisting transparent and opaque minerals can be similar to or obviously different from each other. Generally, wolframite can effectively preserve primary inclusions （with only small amounts of secondary inclusions）, whereas primary inclusions have almost been destroyed in associated quartz. The inclusions observed should be mainly secondary inclusions or inclusions captured during late crystallization. Only the crystals and associated wolframitein drusy cavities subjected to no late stress and fluid transformation have the same result. There are abundant both secondary inclusions and primary inclusions in beryls. Silicate melt inclusions were found in wolframite and beryl, indicating that the mineralization of the Xihuashan tungsten deposit began at the magmahydrothermal transition stage. The initial ore-forming fluid was probably a magmatichydrothermal transitional fluid, which subsequently evolved into single hydrothermal solutions. In the authors＇ opinion, the comparative research on fluid inclusions in coexisting transparent minerals and opaque minerals is important for the study of metal deposits. Detailed basic geological study and petrographic observation are essential. Cautiousness must be taken when we explain the geological significance of a metal deposit, especially when we only use the transparent mineral inclusion data.