花岗岩中黑云母地球化学特征对铟矿化的启示:以栾川矿集区鱼库‒石宝沟岩体为例  

Biotite Geochemistry of the Yuku-Shibaogou Intrusion,Luanchuan Ore District:Implications for Indium Mineralization

作　　者：陈程 韩江伟[4] 徐净[5] 赵太平 CHEN Cheng;HAN Jiangwei;XU Jing;ZHAO Taiping(Key Laboratory of Mineralogy and Metallogeny,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;CAS Center for Excellence in Deep Earth Science,Guangzhou 510640,Guangdong,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Henan Institute of Geological Survey,Zhengzhou 450001,Henan,China;Zijin School of Geology and Mining,Fuzhou University,Fuzhou 350108,Fujian,China)

机构地区：[1]中国科学院广州地球化学研究所矿物学与成矿学重点实验室,广东广州510640 [2]中国科学院深地科学卓越创新中心,广东广州510640 [3]中国科学院大学地球与行星科学学院,北京100049 [4]河南省地质调查院,河南郑州450001 [5]福州大学紫金地质与矿业学院,福建福州350108

出　　处：《大地构造与成矿学》2024年第4期754-770,共17页Geotectonica et Metallogenia

基　　金：国家自然科学基金项目(92062102、41872088)资助。

摘　　要：传统观点认为,铟常在锡多金属矿床中富集。但近年来发现,一些与花岗岩有关的贫锡多金属矿床中,铟也能够富集到一定程度。不可否认的是,无论在贫锡还是富锡的矿床中,铟的富集均与花岗质岩浆活动密切相关。然而,目前对于岩浆演化过程中控制In超常富集的因素尚不清楚。在花岗岩中,黑云母是Sn和In的重要载体矿物,其化学成分也可以有效反映岩浆成因及成岩物理化学条件。栾川矿集区的赤土店矿床为贫锡富铟的岩浆热液铅锌银矿床,其矿化与燕山期鱼库-石宝沟花岗岩关系密切。本文以鱼库-石宝沟花岗岩作为贫锡花岗岩的代表,对岩体中的黑云母开展了详细的矿物地球化学研究,并与华南典型锡铟矿化花岗岩中的黑云母进行对比。结果表明,鱼库-石宝沟花岗岩中的黑云母为镁质黑云母,华南锡铟矿化花岗岩中的黑云母为铁质黑云母-铁叶云母。且鱼库-石宝沟花岗岩中的黑云母具有较低的Sn、In含量,指示该花岗质岩浆贫锡和铟,而华南锡铟矿化花岗岩岩浆源区本身就富锡和铟。与鱼库-石宝沟花岗岩相比,华南锡铟矿化花岗岩起源于变沉积岩的部分熔融,且具有高温、低氧逸度、高挥发分的特征,这些物理化学条件对铟矿化有重要控制作用。而贫锡铟的鱼库-石宝沟花岗岩并不具备这些有利于铟矿化的条件,与之相关的矿床中之所以出现铟的富集,可能与后期地质事件使矿体中的In元素发生活化和再富集有关。Indium,as a critical metal,exhibits geochemical behaviors similar to those of Sn during ore-forming processes.Sn-polymetallic deposits formed in the magmatic-hydrothermal system are the most important sources for indium resources worldwide.Recently,Sn-poor magmatic-hydrothermal deposits with conspicuous indium enrichments have been found in China,indicating the great potential of indium resources.Previous studies have suggested that granitic magma is the source of indium,regardless whether the deposits are Sn-poor or Sn-rich.However,the indium enrichment mechanism during magma processes is poorly understood.The Chitudian Pb-Zn-Ag deposit,located in the Luanchuan ore district,is a typical example that is Sn-poor deposit with high indium content.The mineralization of this deposit is considered to be associated with a Yanshanian intrusion named Yuku-Shibaogou granite(YSG).Biotite is an important carrier of indium and tin,and its chemical composition can be used to characterize the physicochemical conditions of magmatic and hydrothermal systems.In this study,Electron Probe Microanalysis(EPMA)and Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry(LA-ICP-MS)were used to investigate the mineralogy and geochemistry of biotite from YSG,and the results were compared with those of Sn-In mineralized granites(SIG)in south China,aiming to identify factors controlling indium enrichment during magma processes.The results show that the biotites from YSG are Fe-biotite,whereas those from SIG are Mg-biotite or siderophllite.The indium and tin contents of the former are higher than those of the latter,suggesting that SIG is significantly rich in indium and tin relative to YSG.Moreover,the biotite geochemistry indicates that SIG,derived from the partial melting of metasedimentary rock,is characterized by higher temperature,higher volatile contents,and lower oxygen fugacity than YSG.Such favorable conditions may play an important role in Sn-In mineralization in South China.However,the physicochemical conditions of YSG are qui

关 键 词：栾川矿集区 鱼库‒宝沟岩体 黑云母 矿物地球化学 In的富集机制 

分 类 号：P611[天文地球—矿床学]