对柿竹园矽卡岩成因及其成矿作用的新认识

NOVEL KNOWLEDGE ON THE ORIGIN AND MINERALIZATION OF SKARNS FROM SHIZHUYUAN

本文将报导柿竹园W、Sn、Mo、Bi矿床中矽卡岩矿物——石榴子石和辉石成分和石榴子石中熔融包裹体研究结果。对不同中段的16块砂卡岩样品（94％的标本采自第Ⅲ矿带）中的石榴子石和辉正进行了电子探针分析，共获得230个测点的数据。此外，还对上述中段大部分样品里的石榴子石和辉石进行了从边部到核心成分测定．共获得13个样品的97个测点数据。研究结果表明，绝大多数石榴子石属于含Alm十Sps－Pyr＜13％（mol）的钙铁榴石-钙铝榴石固溶体系列，其成分变化范围很大。辉石为含Jo＜11％（mol）的钙铁辉石-透辉石固溶体系列。探针分析资料显示，石榴子石和辉石成分不仅在空间上有变化，而且在同一切片不同颗粒中和在同一颗粒的不同部位中均有变化。只不过其变化程度不同而已。比较而言，石榴子石成分远比辉石的大。大多数单个石榴子石颗粒从边缘至核部的端员成分呈不大的波浪形变化，其变化范围基本上在10％（mol）以内。只有Shi24样品中的石榴子石从边缘至核心的变化中，在颗粒边缘的成分变化大。石榴子石内部相当大一部分的成分基本上无变化。辉石成分八颗粒边缘至核心变化很小。石榴子石中有大量熔融包裹体和熔一流包裹体存在，其均一温度在960～1110℃之间。这些资料向人们传递了一个信息，即该矿床的形?

The compositions of garnet and pyroxene and the homogeneous temperatures of silicatemelt inclusions in garnets from skarn samples at the Shizhuyuan deposit are presented in this paper. Garnets and pyroxenes show a wide range of variations in composition,but most of the garnetsare andradite-grossular solid solutions containing less than 13 mol % (almandine+spessaritine+py-rope), whereas most pyroxenes are hedenbergite-diopside solid solutions containing.less than 11mol% johannesenite. The existence of silicate melt inclusions and melt-fluid inclusions in skarnsamples provides strong evidence for magma crystallization.A wide range of chemical compositions of main skarn minerals is probably caused by the diversity and inhomogeneity of magmatic composition. Magmatic metallization during skarn formationand superposition of postmagmatic ore formation, especially greisenization and f1uoritization, areprobably one of the main causes for the formation of super-large deposits.