福建省紫金山矿田龙江亭矿床地质和成矿流体特征及成因意义  

Geological and ore-fluid characteristics of Longjiangting Cu deposit in Zijinshan Orefield, Fujian Province, and their genetic implications

作　　者：陈静[1] 陈衍景[1] 钟军[1] 孙艺[1] 祁进平[2] 李晶[2] 

机构地区：[1]北京大学造山带与地壳演化重点实验室,北京100871 [2]紫金矿业集团股份有限公司,福建上杭364200

出　　处：《矿床地质》2015年第1期98-118,共21页Mineral Deposits

基　　金：国家科技支撑计划(编号:2009BAB43B04)的资助

摘　　要：龙江亭矿床地处福建省紫金山矿田的西南部,矿体受北西向断裂控制,产于燕山早期中细粒花岗岩中。含矿岩体整体遭受硅化-绢云母化-伊利石化-蒙脱石化,浅部为强硅化-迪开石化,深部保留有钾化;后期蚀变主要分布在地表,为硅化-高岭土化和褐铁矿化,偶见萤石化、重晶石化、石膏化。矿物组合和穿插关系显示,成矿前为无矿石英脉;成矿期脉体矿物组合为石英-绢云母-黄铁矿-铜硫化物;成矿后脉体矿物组合为石英-方解石±石膏。根据矿石组构和铜硫化物类型,成矿期脉体可细分为3个亚类或阶段:早阶段为黄铁矿-黄铜矿组合,浸染状和网脉浸染状构造,见于矿体深部;中阶段为黄铁矿-黄铜矿-斑铜矿-硫砷铜矿组合,具梳状、胶状或皮壳状构造,见于矿体中部;晚阶段为蓝辉铜矿-铜蓝组合,浸染状或晶簇构造,见于浅部坑道和地表。早阶段脉体矿物含大量富液相包裹体,少量富气相包裹体,均一温度为262~403℃,w(Na Cleq)介于0.2%~18.6%,显示中-高温热液的特征;中阶段脉体中的包裹体几乎全部均一到液相,完全均一温度为201~302℃,峰值为250℃,w(Na Cleq)介于0.2%~10.1%,总体显示中-低温热液的特征;晚阶段包裹体全部均一到液相,均一温度为117~250℃,w(Na Cleq)介于0.4%~9.5%之间,表现出低温、低盐度大气降水热液的特征。根据蚀变类型确定成矿期logf(O2)=-42^-38,p H值=3~5;根据金属矿物组合估算出中阶段logf(S2)=-9±,晚阶段logf(S2)=-6.5±。龙江亭矿床硫逸度-温度变化规律不同于世界上其他岩浆-流体成矿系统,可能经历了2次成矿事件,后期的高硫型浅成低温热液成矿作用叠加在早期的斑岩型矿床之上,一方面造成了复杂多样的蚀变类型、矿物组合和矿石组构,另一方面继承、残留了斑岩型矿床的特征。因此,其属于叠合成因的斑岩型-浅成低温热液型矿床,而非斑岩型与浅成低温热液型之间的过渡�The Longjiangting Cu deposit is located in the southwest of the Zijinshan orefield, Fujian Province. It is hosted in the Early Yanshanian granites and structurally controlled by the NW-trending faults. The ore-hosting granite was wholly altered by quartz-sericite-illite-montmorillonite association, with limited quartz-potassic feldspar zone at depth, but strong quartz-dickite alteration in the shallow part. The post-ore silicification, Kaolinite and limonitesalteration are mainly present at the surface. Crosscutting relationships show that the pre-ore, syn-ore and post-ore veins are dominated by mineralogical associations of sulfide-barren quartz, quartz-sericite-pyrite-copper sulfides and quartz-calcite ± gypsum, respectively. On the basis of the ore structure and mineral assemblages, the syn-ore veining period can be subdivided into three stages. The early-stage veins mainly occur in the deep part of the orebody,containing pyrite and chalcopyrite as ore minerals which occur as spotted disseminations, disseminated veinlets and stockworks. The middle-stage veins contain pyrite, chalcopyrite, bornite and enargite, and show comb, colloform and crustiform structures. The late-stage veins are represented by the assemblage of digenite-covellite, and show dissemination and drusy structures. The early stage minerals contain aqueous fluid inclusions with variable vapor /liquid ratios, with homogenization temperatures of 262 ~ 403℃（ peak around 250℃） and salinity of 0. 2% ~18. 6%. Only liquid-rich aqueous inclusions can be observed in minerals of middle and late stages, which yield homogenization temperatures of 201 ~ 302℃ for middle stage, and 117 ~ 250℃ for late stage, corresponding to salinities of 0. 2% ~ 10. 1% and 0. 4% ~ 9. 5%, respectively, indicating that the epithermal Na Cl-H2 O system was dominated by meteoric water. According to the types of hydrothermal alterations, the logf（ O2） and p H values are estimated to be- 42 to- 38, and 3 to 5, respectively. The logf（ S2）（ sulfur fugacity）

关 键 词：地球化学 地质特征 流体包裹体 龙江亭矿床 紫金山矿田 

分 类 号：P618.41[天文地球—矿床学]