赣北大湖塘钨矿成岩成矿物质来源的矿物学和同位素示踪研究  

Sources of granitoids and ore-forming materials of Dahutang tungsten deposit in northern Jiangxi Province: Constraints from mineralogy and isotopic tracing

作　　者：王辉[1] 丰成友[1] 李大新[1] 项新葵[2] 周建厚[1] 

机构地区：[1]中国地质科学院矿产资源研究所,国土资源部成矿作用与资源评价重点实验室,北京100037 [2]江西省地质矿产勘查开发局916大队,九江332100

出　　处：《岩石学报》2015年第3期725-739,共15页Acta Petrologica Sinica

基　　金：国家重点基础研究发展计划973项目(2012CB416704);中国地质调查局高层次地质人才培养计划(201309);青年地质英才计划(201112)联合资助

摘　　要：赣北大湖塘超大型钨矿位于九岭钨多金属矿集区东部。本文对大湖塘钨矿石门寺矿段矿物学特征进行了系统的研究,结合同位素示踪分析了成岩成矿物质来源。岩相学研究表明,石门寺矿段蚀变以黑云母化、云英岩化及碱交代(钾长石化、钠长石化)作用为主。黑云母化的过程中释放了一定量的挥发分,云英岩化和碱交代作用除萃取部分的成矿物质外,使岩体中的Ca2+大量活化迁移。晋宁晚期黑云母花岗闪长岩与燕山中期似斑状花岗岩、花岗斑岩矿物成分研究表明:(1)斜长石普遍富钠,似伟晶岩壳主晶为钾长石,客晶为钠长石;(2)黑云母具有富铁贫镁的特点,黑云母花岗闪长岩及似斑状花岗岩中的黑云母均为铁质黑云母,花岗斑岩中黑云母为铁叶云母。黑云母成分指示大湖塘石门寺矿段花岗岩类均为过铝质S型花岗岩,成岩物质均为壳源。石英氢、氧同位素及黑钨矿氧同位素研究表明成矿流体为岩浆水。黄铜矿、辉钼矿硫同位素表明成矿流体中硫来自于岩浆。结合前人研究成果,本文认为富钨的双桥山群浅变质岩在燕山中期发生了部分熔融,产生了高分异的富含钨元素及挥发分的岩浆,岩浆分异演化过程中形成的含矿热液使侵入体自身及围岩发生大规模的蚀变作用,进而在燕山中期侵入岩的内外接触带形成了大湖塘超大型钨多金属矿床。The Dahutang super-large tungsten deposit in North Jiangxi is located in the eastern area of Jiuling tungsten-polymetallic ore concentration region. The studies of mineralogy and isotope tracing were carried out to help understand the diagenetic and metallogenic material sources of Dahutang tungsten deposit. Petrographical studies indicate that the main alteration types include biotitization,greisenization and alkali metasomatism（ potassic feldspathization,albitization） in Shimensi ore block. A certain amount of volatile was released during the biotitization. The greisenization and alkali metasomatism caused the activation and migration of Ca2 ＋in intrusions,as well as the extraction of some ore materials. The compositions of main minerals in Late Jinningian biotite granodiorite and Middle Yanshanian porphyritic granite and granite porphyry show：（ 1） plagioclases are characterized by high Na and the main crystal is K-feldspar and chadacryst is albite in the pegmatoid crust;（ 2） biotites are characterized by high Fe and low Mg. Biotites in biotite granodiorite and porphyritic granite belong to ferri-biotite and those are siderophyllite in granite porphyry. The composition of biotites indicates that granitoid rocks of Shimensi ore block in Dahutang deposit belong to S-type granite and they are crust-derived. The hydrogen and oxygen isotope of ore-bearing quartz and oxygen isotope of wolframite show that ore-forming fluid is derived from magmatic water. The sulfur isotope of chalcopyrite and molybdenite indicates that sulfur in ore-forming fluid is derived from magma. Based on the previous research results,it is concluded that highly fractionated magma was formed by partial melting of tungsten-rich Shuangqiaoshan Group metamorphic rock in Middle Yanshanian. The ore-bearing fluid which was formed in magmatic differentiation evolution process brought about widespread alteration in intrusions and wall rock,and subsequently Dahutang super-large tungsten polymetallic deposit developed near the contact of

关 键 词：矿物学 同位素示踪 成岩成矿物质来源 大湖塘钨矿 石门寺 赣北 

分 类 号：P595[天文地球—地球化学] P618.67[天文地球—地质学]