赣杭构造带灵山花岗岩体黑云母的矿物化学特征及其对岩石成因的指示意义

发布时间：2018-06-26 18:38

本文选题：黑云母 + 矿物化学　；参考：《岩石学报》2017年03期

【摘要】：灵山花岗岩体在平面上为一环状分布的侵入体,中心为角闪石黑云母花岗岩,外围为黑云母花岗岩。在角闪石黑云母花岗岩中分布有大量的暗色镁铁质微粒包体。黑云母是大多数中酸性火成岩中比较重要的一种镁铁质矿物,它能很好地反映寄主岩浆的属性和成岩时的物理、化学条件,因此,本文对这两种花岗岩及镁铁质微粒包体中的黑云母开展了系统的岩相学观察和电子探针化学组成研究,探讨灵山岩体的物质来源、成岩条件和岩浆的混合作用过程。研究结果表明两种花岗岩体的黑云母具有不同化学成分,而暗色镁铁质微粒包体中黑云母的化学成分则变化较大。三种黑云母均在低氧逸度条件下晶出。两种花岗岩中的黑云母均富Fe贫Mg,属于铁质黑云母,含铁系数[(Fe~(3+)+Fe~(2+))/(Fe~(3+)+Fe~(2+)+Mg~(2+))]分别为0.65~0.70,0.72~0.78,FeOT/MgO均接近7.04。MF值[2×Mg/(Fe~(2+)+Mg+Mn)]分别为0.64~0.76和0.48~0.60,指示两种花岗岩的物质来源都是以壳源为主。镁铁质微粒包体中黑云母的MF值变化范围比较大,为0.63~1.06,为铁质黑云母到镁质黑云母,暗示包体岩浆经历过不同程度的岩浆混合作用。镁铁质微粒包体中部分黑云母与角闪石黑云母花岗岩中黑云母的结晶条件相似,而部分则有明显差异,推测是由于基性的镁铁质包体岩浆注入到酸性的花岗岩浆是一个连续多阶段的过程。
[Abstract]:The Lingshan granite body is a ring distributed intrusive body on the plane with amphibole biotite granite at the center and biotite granite on the periphery. In amphibole biotite granite, there are a large number of dark magnesia-iron particle inclusions. Biotite is an important mafic mineral in most intermediate-acid igneous rocks. It can well reflect the properties of host magma and the physical and chemical conditions of diagenesis. In this paper, the biotite in the granites and magnesia-ferrite inclusions have been systematically studied by petrographic observation and electron probe chemical composition, and the material source, diagenetic conditions and magmatic mixing process of Lingshan rock mass have been discussed. The results show that the biotite of the two granites has different chemical composition, while the chemical composition of the biotite in the dark magnesium-iron particle package varies greatly. All of the three biotite were crystallized under low oxygen fugacity. The biotite of the two granites is rich in Fe and Mg-rich, and belongs to ferric biotite. The iron coefficient [(Fe3 Fe2) / (Fe3 Fe2 Mg2)] is 0.65 0.702.0.78FeOT / MgO close to 7.04.MF [2 脳 Mg2 / Fe2 mg mn] 0.640.76 and 0.48mg 0.60, respectively, indicating that the material sources of the two granites are mainly from shell source. The MF value of biotite in magnesium-iron microparticle inclusions varies from 0.63 to 1.06, indicating that the inclusion magma experienced magmatic mixing to varying degrees. The crystallization conditions of biotite in magnesium-iron particle inclusions are similar to those in hornblende biotite granites, but there are obvious differences in some of them. It is assumed that the injection of basic magnesia-iron inclusion magma into acidic granite magma is a continuous multi-stage process.
【作者单位】：中国地质大学地质过程与矿产资源国家重点实验室;成都理工大学地球科学学院;
【基金】：国家自然科学基金项目(41403022) 中央高校基本科研业务费专项资金资助项目(CUGL150401)联合资助
【分类号】：P588.121

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