花岗岩的应变分析和定位机制

STRAIN ANALYSIS AND EMPLACEMENT MECHANISM OF GRANITE

本文介绍了利用变形椭球体理论,对花岗岩组构(叶理、线理)进行应变分析的方法。花岗岩的变质组构(塑性变形)包括:布丁(石香肠)、压力影、多米诺骨牌剪切构造及C—S 组构。花岗岩的定位机制有以下两种:1)主动(强力)定位,如底辟作用和热轻气球膨胀作用;2)被动定位,如火山口沉陷及顶蚀。通过对花岗岩组构的应变测量和计算,将获得有关岩桨岩形成和演化机制、变形特征及区域构造环境的详细情况。

This paper introduces the method for a strain analysis of the fabric(fo- liation and lineation)of granite by using the theory of the strain ellipsoid.The axial ratio is usually measured on two of the XY,YZ and XZ planes of a xenoiith(or dioritic melanocratic enclave),then the K value is calculated,i.e. the deformation features may be judged.The metamorphic tabric(plastic deformation)of granite includes boudinage,pressure shadow,domino,shear structure and C-S fabric. Two mechanisms of granite emplacement may be considered:(1)active (forceful)emplacement,such as diapirism and ballooning;(2)passive empla- cement,such as cauldron subsidence and stoping.A detailed knowledge of the mechanism of formation and evolution of magmas,deformation features and regional tectonic environments may be gained through the strain measurement and calculation of granite fabric.