论文部分内容阅读
文象花岗岩具有特殊文象结构,研究其三维拓扑结构和形成过程有助于了解花岗质岩石的结晶作用.以北京周口店房山岩体和湖北罗田蕙兰山的文象花岗岩为研究对象,综合利用光学显微镜、扫描电镜、电子探针和电子背散射衍射等技术方法,对岩石矿物组成、结晶学取向和拓扑结构进行了系统研究.结果表明:(1)文象花岗岩的矿物组成与其形成地质环境有关,石英和长石的含量变化范围很大,其中石英含量通常在20%~45%,但是相同地区同期形成的文象花岗岩具有相对稳定的矿物组成;(2)长石作为寄主矿物通常呈半自形-自形粗大晶体,可以是碱性长石或斜长石,其端元组分以钾长石和钠长石为主,低温下常分解为条纹长石;(3)石英在长石寄主矿物中规则穿插生长,在三维空间通常呈近似平行板状、长条状/柱状或非连通枝杈状,并只在特定岩石断面形似象形文字;(4)正交偏光显微镜下,石英可以具有多种消光位,但是通常在一定范围内同时消光;(5)石英普遍发育道芬双晶,偶见日本双晶;(6)条纹长石中钾长石与钠长石对应(100)、(010)、(001)面和[001]轴近似平行;(7)多数石英颗粒与寄主长石之间具有密切结晶学取向关系,即石英[1123]轴近似平行长石c[001]轴.该研究证实文象花岗岩是石英和长石同时生长的结果,而长石作为寄主矿物影响并控制着石英的成核与生长方向.
The study of its three-dimensional topological structure and formation process is of help to understand the crystallization of granitic rocks.Warmly granite from the Fangshan granite in Zhoukoudian in Beijing and the Huilan Mountain in Hubei Province is used as the research object, and the comprehensive utilization Optical microscopy, scanning electron microscopy (SEM), electron probe and electron backscatter diffraction, etc. The results show that: (1) the mineral composition of the Wenxiang granite is similar to that of the geologic environment The contents of quartz, quartz and feldspar vary widely, with the quartz content usually ranging from 20% to 45%, but the similar granites in the same area have the relatively stable mineral composition. (2) The feldspar, as the host mineral, is usually Semi-self-shaped - self-shaped coarse crystals, which can be alkaline feldspar or plagioclase, the terminal element of potassium feldspar and albite-based, often decomposed into stripe feldspar at low temperatures; (3) quartz in the long Stone host minerals regularly interspersed growth, usually in the three-dimensional space is approximately parallel plate, strip / columnar or non-connected twig-like, and only in a specific rock section shaped like hieroglyphs; (4) orthogonal Microscope, quartz can have a variety of extinction, but usually within a certain range at the same time extinction; (5) Quartz generally developed Tao Fen twins, occasionally Japanese twins; (6) striped feldspar K and f The (001) plane is approximately parallel to the [001] axis corresponding to the (100), (010), and (001) planes. (7) Most quartz grains have a close crystallographic orientation with the host feldspar, The rock c [001] axis, which confirms that the granite is a result of simultaneous growth of quartz and feldspar, while feldspar, as the host mineral, influences and controls the nucleation and growth of quartz.