一个奇异透镜体构造的微束分析

MICRO-BEAM ANALYSIS OF A PECULIAR LENTICULAR STRUCTURE

奇异透镜体构造标本采自南京幕府山经强烈挤压的灰岩地层。通过SEM和EPMA测试,透镜体构造的中层和内核之间边界有挤压、剪切和拉张三种变形。自外层和内层一些主要元素Ca、Si、P和S等的变化有一定的规律。这些现象的产生是由应力作用、动力分异作用和动热变质作用的结果。

A geological sample with a peculiar lenticular structure sample was collected from li-mestone strata at Mt. Mufu in Nanjing. The rocks in the structural zone have undergone strong compressive, plastic flow and ductile deformation. Microscopically, the sample can be divided into three layers, i.e., outer fine-grained limestone, middle coarse-grained limes-tone and inner siliceous nodule. The following characteristics have been revealed by SEM and EPMA analyses:1. Compressive, shear and tensile deformation is discernible at the boundary between the middle layer and the inner nodule.2. Some major elements (Ca, Si, P and S) show regular variations from the outer part to the core.3. The phenomena mentioned above may be ascribed to post-sedimentary tectonic pro-cesses, including stress action, dynamic differentiation and dynamothermal metamorphism.