欢迎访问《高校地质学报》官方网站,今天是
分享到:

高校地质学报

• 矿物·岩石·矿床·地球化学 • 上一篇    下一篇

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

马莲花,蔡永丰,刘希军,许继峰,周 云,苏小倩   

  • 出版日期:2018-10-20 发布日期:2018-10-15

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

MA Lianhua, CAI Yongfeng, LIU Xijun, XU Jifeng, ZHOU Yun, SU Xiaoqian   

  • Online:2018-10-20 Published:2018-10-15

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。

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

Abstract: 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.

Key words: biotite, granite, mineral composition, petrogenesis, mineralization, Kafang orefield