云南个旧卡房锡矿田花岗岩黑云母矿物化学特征及其成岩成矿意义  

Chemical Composition of Biotite from the Gejiu Granite,Yunnan Province: Implication for Petrogenesis and Mineralization of Kafang Tin Polymetallic Deposit

作　　者：马莲花 蔡永丰 刘希军 许继峰 周云 苏小倩 MA Lianhua;CAI Yongfeng;LIU Xijun;XU Jifeng;ZHOU Yun;SU Xiaoqian(Collaborative Innovation Center for Exploration of Hidden Nonferrous Metal Deposits and Development of New Materials in Guangxi&Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration,Guilin University of Technology,Guilin 541004,China;School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China)

机构地区：[1]桂林理工大学广西有色金属隐伏矿床勘查及材料开发协同创新中心,广西隐伏金属矿产勘查重点实验室,桂林541004 [2]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《高校地质学报》2018年第5期692-701,共10页Geological Journal of China Universities

基　　金：国家自然科学基金(41502180；41503021)；广西自然科学基金项目(2015GXNSFBA139204；2017GXNSFAA198209)；广西高等学校科学研究项目(KY2015ZD052)；广西“八桂学者”创新团队项目(2013，有色金属成矿理论与勘查技术)联合资助。

摘　　要：黑云母作为花岗岩中含量最高的暗色矿物,其成分特征对指示岩石成因与成矿起着重要作用。云南个旧卡房锡多金属矿床的形成与花岗质岩浆活动密切相关,卡房花岗岩包含有大量黑云母,通过电子探针测试方法,对该花岗岩中的黑云母成分进行了系统的研究。结果显示,黑云母为富铁黑云母,具有富硅、铁、铝、钾、钛,贫锰、镁、钙、钠等特征,含铁指数为0.67～0.83。黑云母的成分特征暗示其结晶温度为500～708℃,结晶压力为202～538 MPa,对应的结晶深度为7.64～20.35 km,表明卡房花岗岩形成于中低温环境、属于中深成相。综合研究认为,卡房锡矿田花岗岩具有高铁指数以及氧逸度由高到低变化趋势等特征是锡成矿的有利条件,可以作为在本区寻找锡矿的重要标志。Mineralization of the Kafang tin polymetallic deposit is closely related to granitic magmatism.The chemical composition of biotite,which is the most common mafic mineral in granite,has been used to reveal petrogenesis and mineralization.Detailed chemical compositions of biotite from the Kafang granite of the Gejiu tin orefield,a famous tin polymetallic deposit in China,are presented in this study.Results of electron microprobe analyzer(EMPA)indicate that the biotite has high SiO2,FeOT,Al2O3,K2O and TiO2,and low MgO,CaO,Na2O and MnO contents,with Fe/(Fe+Mg)values of 0.67-0.83,resembling those of iron biotite.These characteristics suggest that their host granites were mainly originated from partial melting of crustal materials.Calculation results of biotite thermometers,Al-in-biotite barometer and oxygen fugacity estimation suggest that they have high crystallization temperatures of 500-708℃,crystallization pressure of 202-538 MPa with corresponding crystallization depth of 7.64-20.35 km,and oxygen fugacities from high to low.Integrated with regional geological data,we propose that high iron indexes and from high to low oxygen fugacities of the biotite from Kafang granite are favored for Sn mineralization.These characteristics could be key tracers for Sn exploration.

关 键 词：黑云母 花岗岩 矿物成分 岩石成因 成矿作用 卡房锡矿田 

分 类 号：P575.1[天文地球—矿物学] P581[天文地球—地质学]