海南岛石碌矽卡岩铁矿石中石榴子石的熔融包裹体及其意义  

Finding of melt inclusion in garnet from skarn of Shilu iron deposit,Hainan province.

作　　者：赵劲松[1,2,3] 夏斌[2] 丘学林[1] 赵斌[2] 许德如[2] 冯佐海[4] 李兆麟[5] 沈敢富[6] 胡瑞忠[7] 苏文超[7] 秦朝建[7] 秦伟民 符贤 胡志高[8] 

机构地区：[1]中国科学院南海海洋研究所,广州510301 [2]中国科学院广州地球化学研究所,广州510640 [3]中国科学院研究生院,北京100049 [4]桂林工学院资源与环境工程系,桂林541004 [5]中山大学地质系,广州510275 [6]成都地质矿产研究所,成都610082 [7]中国科学院地球化学研究所,贵阳550002 [8]海南钢铁公司地质测量处,昌江572700

出　　处：《岩石学报》2008年第1期149-160,共12页Acta Petrologica Sinica

基　　金：国土资源部“海南省昌江县石碌铁矿接替资源勘查项目”(项目编号为：200646092);中国科学院广州地球化学研究所边缘海开放实验室及中国科学院地球化学研究所矿床地球化学开放实验室的联合资助

摘　　要：对石碌铁矿一块具有代表性的新鲜矽卡岩铁矿石标本进行了岩石薄片显微镜观察、电子探针和喇曼光谱分析研究。在石榴子石中发现了熔融包裹体。这些包裹体主要特点是大小悬殊和成群或成带分布,最大者达98μm×5μm,最小者为1μm×1μm,多数包裹体长约5～30μm,宽约2～7μm,也有不少呈孤立状散布在石榴子石中。其形态多样,呈纺锤形、哑铃形,串珠状,藕形,近圆形和不规则状。研究的矽卡岩主要由钙铁榴石组分高的石榴子石、磁铁矿、石英、透闪石和透辉石组成,还有呈定向和星点分布的磷灰石,少量锆石与榍石;石榴子石中的熔融包裹体捕获的熔体由含Ca、Fe、Al和挥发分(H_2O和CO_2)的硅酸盐熔融体组成。在熔融包裹体冷却过程中,由于温度缓慢降低,赤铁矿、钙铁榴石、石英、方解石和透辉石从上述硅酸盐熔体中析出,剩下的残余熔体不混溶,变成含有Ca和Si等杂质的铁质熔体、含Si、Fe的碳酸盐熔体和含Ca、Al、Fe的硅酸盐熔体。喇曼光谱测定显示,石榴子石中熔融包裹体含有石榴子石、赤铁矿和方解石,个别含少量水蒸气。磁铁矿含有可疑的Fe、Si熔融包裹体和Si、Fe熔融包裹体。在透辉石-透闪石矽卡岩铁矿石的石榴子石里发现大量熔融包裹体的事实无疑。矽卡岩铁矿石石榴子石中熔融包裹体的首次发现,它可能有助于石碌铁矿床挖掘老矿潜力和拓宽找矿的新思路。Observations of thin sections of rocks from a fresh and representative specimen of iron ore of skarn type under polarized light microscope, electron probing analyses and Raman analyses for minerals and melt inclusions were carried out. Melt inclusions in garnet have been found. Main characteristics of these inclusions are great disparities in varying sizes and distributions in groups and in zones, the largest melt inclusion is up to 98μm x5μm, the smallest one is about lμm x lμm, the majority of the melt inclusions are 5-30μm in length and 2-7μm in width. Some melt inclusions are scattered within garnet in isolation. They have variety in the shape and they total spindle, dumbbell, string of beads, lotus root, round-like and xenomorphic forms. Stadied skarn mainly consists of garnet with high component of andradite, magnetite, quartz, tremolite and pyroxene, apatite with directional and sporadic distributions, minor zircon and sphene. Melts trapped by melt inclusions in garnet originally consisted of Ca, Fe, AI and volatile components （H20 and CO2 ） bearing silicate melt. During cooling process of the melt inclusions, hematite, andradite, quartz, calcite and diopside separated out from the silicate melt mentioned above due to slowly cooling, immiscibility of residual melts occurred, Ca and Si-bearing iron melt , Si and Fe-bearing carbonate melt, and Ca, A1, Fe-bearing silicate melt formed respectively： Raman analyses show that the melt inclusions in garnet contain garnet, hematite and calcite; only one melt inclusion contains water vapour. Magnetite mainly contains questionable melt inclusions with silica and iron of variable proportion. Fact that a large number of melt inclusions in the garnet from iron ore of skarn type within diopside-tremolite rock have been found is undoubted. The melt inclusions were observed for the first timein garnet in such type of iron ore, which may possibly invoke new ideas in regard to the genetic study on Shilu iron deposit and how to explore in situ ores from the old mi

关 键 词：石碌铁矿 矽卡岩 石榴子石 熔融包裹体 

分 类 号：P618.31[天文地球—矿床学] P588.312[天文地球—地质学]