安徽桂花冲花岗闪长斑岩中黑云母成分特征及地质意义  

GEOLOGICAL SIGNIFICANCE AND COMPOSITION CHARACTERISTICS OF BIOTITE IN GUIHUACHONG GRANODIORITE,ANHUI PROVINCE

作　　者：岳紫龙[1,2] 杜杨松[2] 曹毅[1] 左晓敏[1] 杜静国 

机构地区：[1]中国地质大学(北京),地球科学与资源学院,北京100083 [2]南阳师范学院,珠宝玉雕学院,河南南阳473061

出　　处：《矿物岩石》2016年第2期27-33,共7页Mineralogy and Petrology

基　　金：中国地质调查局项目(12120113069900);南阳师范学院校级项目(ZX2016012)

摘　　要：安徽桂花冲铜矿位于繁昌盆地与铜陵隆褶带的过渡地带,是一新发现的斑岩-矽卡岩复合型铜矿床,成矿时代为白垩纪早期。矿区岩浆岩主要为花岗闪长斑岩,为探究岩浆的起源、成岩物理化学条件,对其斑晶黑云母进行系统的显微岩相学观察和矿物化学研究。电子探针分析结果表明,黑云母MgO,TFeO,Al_2O_3和TiO_2的质量分数分别为14.15%~15.60%,15.17%~16.41%,12.94%~13.49%和3.84%~4.63%,为富镁贫铁低铝高钛,属镁质黑云母。岩石成分、结构、构造等特征表明,该斑岩体属于壳幔混源的Ⅰ型花岗岩,岩浆结晶温度在750℃~780℃之间,氧逸度f(O_2)为1×10^(-12)Pa^1×10^(-10) Pa。通过黑云母全铝压力计算得其压力为49.96 MPa^72.38 MPa,对应的岩浆房深度为1.89km^2.74km,属超浅岩浆房。岩体附近火山岩的存在,是桂花冲地区形成斑岩型铜矿的重要影响因素。The Guihuachong copper deposit is a porphyry-skarn composite type copper deposit newly discovered and formed in the Early Cretaceous,which is located in the transition zone between Fan chang basin and Tongling transitional belt.In this paper,for the study of the origin of magma,diagenesis,physical and chemical conditions,petrographic and mineralogical characteristics of the biotites in Guihuachong granodiorite are investigated,and their forming conditions and the geological significances are discussed.Electron microprobe analysis（EPMA）of the biotites show that the contents of MgO,TFeO,Al2O3 and TiO2 in biotite are 14.15%-15.60%,15.17%-16.41%,12.94% -13.49% and 3.84% -4.63%,respectively,which belong to Mg-biotites,relatively rich in Mg and Ti and poor in Fe and Al.According to the characteristics of biotite composition,The Guihuachong granodiorite belongs to I-type granite.The crystallization temperature（T）and oxygen fugacity f（O2）of the biotites are 750 ℃-780 ℃ and 1×10^-12 Pa-1×10^-10 Pa,respectively.The solidification pressure（P）of the biotites is 49.96 Mpa-72.38 Mpa and the depth of magma chamber is 1.89km-2.74 km,which belongs to the shallow magma chamber.The volcanic rock is an important influence factor for the formation of porphyry copper deposits in the Guihuachong area.

关 键 词：黑云母 花岗闪长斑岩 矿物化学 地质意义 安徽桂花冲 

分 类 号：P575.1[天文地球—矿物学]