新疆西天山哈勒尕提铁铜矿床流体包裹体和氢氧同位素特征及其成矿意义  

Fluid inclusions and H-O isotopes of the Halegati Fe-Cu deposit in the West Tianshan,Xinjiang: Implications for ore genesis

作　　者：何格[1] 顾雪祥[1,2] 王新利[3] 周超[1] 刘瑞萍[4] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]中国地质大学地质过程与矿产资源国家重点实验室,北京100083 [3]鑫达金银开发中心,北京100038 [4]核工业北京地质研究院,北京100029

出　　处：《岩石学报》2016年第6期1795-1808,共14页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(41572062;U1303292;41302064);中央返还两权价款资金综合研究项目(Y15-1-LQ04);国家科技支撑计划项目(2011BAB06B02-02)联合资助

摘　　要：哈勒尕提铁铜矿床位于新疆西天山博罗科努多金属成矿带,矿体呈似层状、透镜状产于晚泥盆世中酸性侵入体与上奥陶统碳酸盐岩接触带上,是一个典型的矽卡岩矿床。本文从流体包裹体和氢氧同位素研究入手,讨论了成矿流体的特征、来源和演化及其与成矿的关系。岩相学观察表明,本矿床热液矿物中流体包裹体存在5种类型:富液相气液两相盐水包裹体(Ⅰ类)、含子矿物多相包裹体(Ⅱ类)、富气相气液两相盐水包裹体(Ⅲ类)、纯液相水包裹体(Ⅳ类)和纯气相水包裹体(Ⅴ类)。其中,Ⅰ类包裹体数量最多,各阶段热液矿物中均有发育;Ⅱ类包裹体数量较少,只见于进化交代蚀变阶段的石榴石和早退化阶段的绿帘石中;Ⅲ、Ⅳ和Ⅴ类包裹体数量最少,主要发育于晚退化阶段的石英和方解石中。流体包裹体显微测温表明,从进化交代蚀变阶段→早退化阶段→晚退化阶段,成矿流体经历了从高温(404~562℃)、中-高盐度(11.1%~51.6%NaC leqv)、中-低密度(0.47~0.80g/cm^3)到中-高温(207~465℃)、中-低盐度(2.9%~44.1%NaC leqv)、中-低密度(0.64~0.89g/cm^3)再到中-低温(117~337℃)、低盐度(1.6%~4.5%NaC leqv)、中-高密度(0.90~0.97g/cm^3)的演化过程。氢氧同位素研究表明,进化交代蚀变阶段和早退化阶段的成矿流体主要源于岩浆水,晚退化阶段则有大气降水的加入。根据流体包裹体岩相学特征,结合矿床宏观地质特征,认为流体不混溶(沸腾)是导致本矿区金属沉淀成矿的主要机制。The Halegati Fe-Cu deposit is located in the Boluokenu polymetallic belt in the West Tianshan,Xinjiang.As a typical skarn deposit,its ore bodies occur as stratoids or lenses at the contact zone between the Late Devonian intermediate to acid intrusive rocks and the Upper Ordovician carbonate rocks.Based on the study of fluid inclusions and hydrogen and oxygen isotopic geochemistry,the aim of this paper is to discuss the characteristics,origin and evolution of ore-forming fluids and to provide an insight into the ore genesis.Petrographic observation indicates that fluid inclusions of the deposit can be divided into five types,i.e.,liquid-rich aqueous inclusions（ type-Ⅰ）,daughter mineral-bearing multiphase inclusions（ type-Ⅱ）,vapor-rich aqueous inclusions（ type-Ⅲ）,monophase liquid（ type-Ⅳ） and vapor aqueous inclusions（ type-Ⅴ）.Type-Ⅰ fluid inclusions are most abundant in all stages of the hydrothermal minerals.Type-Ⅱ fluid inclusions are few and can only be observed in garnet at the prograde metasomatic alteration stage and in epidote at the early retrograde stage.Fluid inclusions of types Ⅲ,Ⅳ and V are smallest in number and commonly exist in quartz and calcite of the late retrograde stage.Microthemometric measurements of fluid inclusions show that from the prograde metasomatic alteration stage to the early retrograde stage and further to the late retrograde stage,the ore-forming fluids experienced an evolution of high temperature（ 404 - 562℃）,high-moderate salinity（ 11.1% - 51.6% Na Cleqv） and moderate-low density（ 0.47 -0.80 g / cm3）,to high-middle temperature（ 207 - 465℃）,moderate-low salinity（ 2.9% - 44.1% Na Cleqv） and moderate-low density（ 0.64 - 0.89g/cm3）,and to middle-low temperature（ 117 - 337℃）,low salinity（ 1.6% - 4.5% Na Cleqv） and high-medium density（ 0.90 - 0.97 g / cm3）.Hydrogen and oxygen isotopic geochemistry shows that the ore-forming fluids of the prograde metasomatic alteration stage and the early retrograde stage w

关 键 词：流体包裹体 氢氧同位素 流体不混溶 哈勒尕提铁铜矿床 新疆 

分 类 号：P597.2[天文地球—地球化学] P618.31[天文地球—地质学]