云南个旧Sn-Cu多金属矿田中酸性岩黑云母特征及其成矿意义  

Compositional characteristics of bitote in felsic igneous rocks and its geological implication in the Gejiu Sn-Cu polymetallic ore field,Yunnan province

作　　者：解世雄 陈喜连 黄文婷[1,2] 张健 廖娟[1,2] 欧阳柳芸 梁华英 XIE Shixiong;CHEN Xilian;HUANG Wenting;ZHANG Jian;LIAO Juan;OUYANG Liuyun;LIANG Huaying(CAS Key Laboratory of Mineralogy and Metallogeny,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;University of Chinese Academy of Sciences,Beijing 100049,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]中国科学院大学,北京100049

出　　处：《地球化学》2023年第2期212-221,共10页Geochimica

基　　金：科技部国家重点研究计划(2016YFC0600407)资助。

摘　　要：Cu和Sn在中酸性岩浆作用过程中地球化学行为明显不同,少见2种类型矿床与同一岩浆作用共生。滇东南个旧Sn-Cu多金属矿田矿床和燕山期岩浆岩联系紧密, Sn-Cu共生,都达超大规模,国内外罕见。目前对个旧矿田Sn-Cu共生控制因素探讨不多。本研究通过矿区二长岩、似斑状花岗岩及其中暗色包体和等粒状花岗岩黑云母电子探针分析,探讨区内岩浆氧逸度及挥发相组成特征,分析其与区内形成Sn-Cu组合矿床的关系。二长岩和似斑状花岗岩及其暗色包体中的黑云母为铁质黑云母,等粒状花岗岩中黑云母属于铁叶云母。似斑状花岗岩和二长岩岩浆氧逸度较高,位于HM缓冲线附近,具较高Cl/F值;等粒状花岗岩浆氧逸度低,分布在NNO缓冲线附近,具较低Cl/F值,表明个旧矿田既发育高氧化及高Cl/F值岩浆,也发育还原及低Cl/F值岩浆。高氧化、高Cl/F值岩浆演化及出溶流体有利于形成Cu矿床,而还原、富F岩浆岩的形成与演化则更有利于形成Sn矿床。因此,个旧矿田Sn-Cu共生可能与区内发育2套性质不同的岩浆系统有关。Cu and Sn exhibit distinct geochemical behaviors during feslic magma evolution,and thus Sn and Cu deposits are rarely co-genetically related with the same magmatism.A series of giant Sn-Cu polymetallic deposits are closely associated with Cretaceous magmatism in the Gejiu orefield,Yunnan province,China,forming granite-related deposits,which show a Sn-Cu association that has not been widely reported globally.The factors controlling Sn-Cu mineralization in the Gejiu orefield have not been widely reported.Here,we evaluated the oxygen fugacity and magmatic volatile characteristics of magmas by analyzing biotite from equigranular granite,porphyritic granite,and its hosting mafic microgranular enclaves,and monzonite in the Gejiu orefield and examined the factors corresponding to the formation of deposits with elemental association of Sn-Cu.The results showed that the biotite of the porphyritic granite,mafic microgranular enclaves,and monzonite belongs to ferri-biotite biotite,whereas the biotite of the equigranular granite belongs to siderophyllite.The porphyritic granite,mafic microgranular enclaves,and monzonite were crystallized from magma with high oxygen fugacity>HM and high Cl/F ratios,whereas the equigranular granite was crystallized from relatively evolved and reduced F-rich magma.Highly evolved,F-rich reduced magma benefits from Sn mineralization,whereas Cl-rich oxidized magma and its exsloving fluids are favorable for Cu enrichment and late-stage mineralization.Therefore,the formation of a series of giant deposits with element association of Sn-Cu in the Gejiu orefield may be related to the highly oxidized and reduced magmatism in the area.

关 键 词：Sn-Cu多金属矿床 黑云母 岩浆氧化还原状态 岩浆挥发分 

分 类 号：P611[天文地球—矿床学]