摘要
太白金矿含金角砾岩带赋存于秦岭泥盆纪浅变质细碎屑岩系中 ,地质特征独特。金矿化主要产于含铁白云石 -黄铁矿等胶结物中 ,这些载金矿物中普遍有大量流体包裹体产出。应用扫描电镜、能谱分析和电子探针技术发现了石英和含铁白云石中的黄铁矿、毒砂和铁白云石等子矿物 ,结合流体包裹体成分 L RM分析资料 。
With the development of SEM/EDS and EPMA,much progress in the study of daughter minerals in fluid inclusions has been made in recent years.However,daughter minerals in fluid inclusions of hydrothermal gold deposits have rarely been reported.This paper focuses on the discovery of daughter minerals in the Taibai gold deposit,Shanxi Province.The Taibai gold deposit is a unique breccia\|cemented gold\|bearing system occurring in Devonian strata of South Qinling Mountains.The breccia zone strikes NWW\|SEE.The cement is mainly composed of ankerite,pyrite,calcite and quartz,which make up four main tectonic\|mineralization stages.Gold mainly occurs in pyrite and ankerite of Stages Ⅱ and Ⅳ.\;There exist a large number of fluid inclusions in ankerite and quartz of the main mineralization stages.Three kinds of fluid inclusions can be recognized:(1)aqueous inclusions (Type B);(2)CO\-2\|rich inclusions(Type C);(3)daughter minerals\|containing inclusions.LRM analysis shows that CO\-2 content is 54\^4～70\^7 mol% in vapor phases of different types of fluid inclusions.H\-2O(g)\|containing vapor phase is an important phenomenon of the Taibai gold deposit.H\-2O(l) content of liquid phase of Type A inclusions is higher than that of Type B,while things are just the opposite for CO\-2 content.CH\-4(5\^2～7\^3mol%)and H\-2S(6\^0～12\^7mol%)exist in both vapor and liquid phases;CO and SO\-2 have also been detected in some samples.Many daughter minerals in fluid inclusions of ankerite and quartz have been found.Several kinds of daughter minerals,including ankerite,pyrite,arsenopyrite and halite,were determined with SEM/EDS technique.EPMA technique was also used to study the daughter minerals exposed at the surface of polished thin sections.\;Stable isotopes of ankerite and quartz from the Taibai gold deposit have been studied.The δ 18 O values of ankerite vary slightly from 17\^6 to 19\^6 per mil(9 samples).The calcula\| ted δ 18 O values of fluid inclusions change from 8\^3 to 15\^2 per mil.The δ D values of inclusion fluids range from-64 to -132 per mil for quartz and -62 to 77 per mil(Shi et al.,1993).The ankerite δ 13 C PDB values of ores are from -5\^2 to -6\^7 per mil.According to the δ 13 C values and the field of magmatic water suggested by Taylor (1979),it may be concluded that the water in the hydrothermal fluids of the main gold mineralization stages might have been derived from the mantle source.However,local meteoric water was probably very important in late mineralization,as implied by low δD values.In summary,characteristics of ore\|froming fluids of the Taibai gold deposit are different either from those of lode gold deposits in Archean greenstone terrains or from those of Carlin type gold deposits.
出处
《矿床地质》
CAS
CSCD
北大核心
2000年第1期54-60,共7页
Mineral Deposits
基金
原冶金部人教司和陕西太白金矿资助项目
