滇西古永地区花岗岩中黑云母成分特征及其成岩成矿意义  

Compositional characteristics, petrogenesis and metallogenic significance of biotite from granite in the Guyong region of Western Yunnan Province, China

作　　者：陈慧军[1,2] 张寿庭[2] 曹华文[2] 王祥发 聂晓亮 张伟[2] 唐利[2] 

机构地区：[1]江西省地矿资源勘查开发中心,江西南昌330030 [2]中国地质大学地球科学与资源学院,北京100083

出　　处：《矿物学报》2015年第2期267-275,共9页Acta Mineralogica Sinica

基　　金：中央高校基本科研业务费专项资金(编号:2652013074);构造成矿成藏国土资源部重点实验室开放基金(编号:2012006);云锡公司科研项目

摘　　要：滇西古永地区花岗岩与锡矿床在成因上密切相关。黑云母的电子探针分析结果表明,古永黑云母二长花岗岩中的黑云母为铁质黑云母,小龙河锡矿床黑云母似斑状二长花岗岩中的黑云母为铁叶云母。两花岗岩体中黑云母总体显示出富铁(w(TFe O)=22.39%~27.91%)贫镁(w(Mg O)=1.08%~10.51%,含镁系数为0.07~0.50)的特征;但两岩体花岗岩中黑云母的化学成分具有明显的差异,古永花岗岩体中黑云母表现出相对富镁,为含幔源物质混入的I型花岗岩;而小龙河成矿花岗岩体中黑云母相对富铝贫镁,为典型壳源过铝质的S型花岗岩。古永花岗岩体和小龙河花岗岩体中黑云母的结晶温度分别为700~750℃、620~650℃,氧逸度(lgf(O2))分别为-14.0^-13.8、-17.5^-17.2。古永岩体花岗岩中黑云母结晶压力为67~120 MPa,结晶深度为2.54~4.55 km。表明本区花岗岩形成于相对高温、低氧逸度、较浅的环境。相对于古永花岗岩体,小龙河花岗岩体具有更大的Sn成矿潜力,更有利于本区锡矿床的形成。The granite from the Guyong region, western Yunnan Province, China is closely associated with Sn deposits. Electron microprobe analyses show that the biotite in the Guyong biotite adamellite is 'ferribiotite', and the biotite from the Xiaolonghe Sn deposits biotite mimophyre adamellite is siderophyllite. Biotite from both plutons are iron-rich(Fe Ot=22.39%- 27.91%) and magnesium-poor(Mg O=1.08%- 10.51%, Magnesium coefficient is 0.07-0.50). Biotite from Guyang granite is magnesium-rich, suggesting I-type granite contaminated by mantle material, while biotite from Xiaolonghe metallogenetic granite is aluminum-rich and magnesium-poor, suggesting typical peraluminous S-type granites of crustal origin. The crystallization temperature for biotite in Guyong granite and Xiaolonghe granite is 700-750 ℃and 620-650 ℃respectively, with the oxygen fugacity lgf(O2) of-14.0--13.8 and-17.5--17.2 respectively. Crystallization pressure for biotite from Guyong granite is 67-120 MPa, indicating a crystallization depth of 2.54-4.55 km. Relatively high temperature, low oxygen fugacity and shallow environments are favored for forming granite in this region. Xiaolonghe granite is more conducive to the formation of Sn deposits and has a higher potential for Sn mineralization than Guyong granite.

关 键 词：黑云母 花岗岩 矿物化学 成岩成矿 滇西古永 

分 类 号：P588.121[天文地球—岩石学] P618.44[天文地球—地质学]