深源富碱硅热流体与斑岩铜矿含矿斑岩体的成因联系及流体包裹体、斑晶结构证据  

GENETIC RELATION BETWEEN DEEP-SEATED ALKALI- RICH HYDROTHERMAL FLUIDS AND ORE-BEARING PORPHYRIES OF PORPHYRY COPPER DEPOSITS EVIDENCE FROM FLUID INCLUSIONS AND PHENOCRYST TEXTURES

作　　者：陈文明[1] 

机构地区：[1]中国地质科学院矿产资源研究所,北京100037

出　　处：《地学前缘》2001年第4期409-421,共13页Earth Science Frontiers

基　　金：国家自然科学基金资助项目 ( 49970 32 )

摘　　要：通过中国几个主要斑岩铜矿含矿斑岩体中斑晶结构及斑晶中流体包裹体的详细研究得出 :斑岩体中的斑晶具明显的包含、筛状、间隙、聚合及次生加大等变斑晶结构。斑晶 (石英 )中流体包裹体具有饱和及过饱和盐水蒸气沸腾流体包裹体组合的特征 ,缺乏熔融包裹体。该沸腾流体包裹体组合(全岩 )中过饱和盐水包裹体占 2 9% ,饱和盐水包裹体占 2 % ,不饱和盐水包裹体占 4 5 % ,气相包裹体占 2 4 %。根据饱和盐水包裹体的均一温度确定斑晶的形成温度区间为 3 11～ 4 0 7℃。流体包裹体的成分主要为H2 O ,CO2 ,K+,Na+,Cl-,SO2 -4等 ,从而进一步论证了斑岩铜矿中含矿斑岩体并非岩浆直接结晶的产物 ,而很可能是由深部富K ,Na ,Si的热流体交代或局部熔融上部含Cu硅酸盐地壳的结果。Detailed study of the textures and fluid inclusions of phenocrysts in ore bearing porphyries of several major porphyry copper deposits in China indicates that the phenocrysts in porphyroblastic textures are of distinct poikilitic, sieve, interstitial, glomeoprphyritic and overgrowth textures. The fluid inclusions in the phenocrysts (quartz) show the features of the assemblage of saturated and oversaturated saline water vapor boiling fluid inclusions and are lacking in melt inclusions. In this boiling fluid inclusion assemblage (whole rock), the oversaturated saline water inclusions make up 29%, saturated saline water inclusion 2%, unsaturated inclusions 45% and vapor inclusions 24% of the assemblage. The formation temperatures of the phenocrysts estimated by homogenization temperatures of saturated saline water inclusion range from 311 ℃to 407℃. The fluid inclusions are dominantly composed of H 2O, CO 2, K +, Na +, Cl -, and SO 2- 4, thus further validating that the ore bearing porphyries in porphyry copper deposits are not the product of direct magmatic crystallization but most likely to be the result of metasomatism or partial melting of the upper copper bearing silicate crust by deep seated K and Na rich siliceous hydrothermal fluids.

关 键 词：流体包裹体 斑晶结构 含铜斑岩体 富碱硅热流体交代作用 气相包裹体 

分 类 号：P575[天文地球—矿物学] P618.41[天文地球—地质学]