云南白秧坪东矿区控矿断裂带构造岩的方解石组构

断裂带构造岩的方解石组构综合分析,可以推断构造活动的应力场方位,利用e双晶的C—T(C—压应力轴,T—张应力轴)图解推断古应力的方位,已为众多的地质学家在实践中引用。云南白秧坪东矿区推覆构造的华昌山断裂带和水磨房断裂带,是矿区的主要控矿构造,其构造岩的方解石及e双晶极点组构均显示点极密加环带的型式,大部分发育近岩组坐标c轴的光轴极密,代表光轴方向的压力导致沿岩组坐标ab面滑动;在C—T应力系统中,显示华昌山、水磨房断裂带晚期较强烈活动的应力场方位,主压应力方向为SE-NW向,主张应力方向为NE-SW向,断层以左旋运动为主;华昌山断裂带SE盘往NW方向逆冲,水磨房断裂带则由NW往SE方向反冲,与野外宏观构造分析吻合。

Calcite fabric of tectonite in an ore-controlling fault belt in the Baiyangping east ore district, Yunnan

We may deduce the stress field orientation in the fault belt by an integrated analysis of the calcite petrofabric in tectonite of a fault belt and deduce the orientation of the paleostress using the C (compressive)-T (tensile) stress diagram of calcite with e-twins. The methods have been applied by many geologists in the practice. In the Baiyangping east ore district of Yunnan, the Huachangshan and Shuimofang faults are the principal ore-controlling structures. The petrofabric diagrams of calcite optic axis and e-twin poles both show c-axis pole maxima and girdles, indicating that the compressive stress in the c-axis direction causes gliding along the ab plane. In the C-T stress system, the principal compressive stress is oriented in a SE-NW direction and the principal tensile stress is oriented in a NE-SW direction, and the sinistral motion predominates for the Huachangshan and Shuimofang faults; the SE block of the Huachangshan fault is thrust in a NW direction, while the Shuimofang fault is thrust antithetically from NW to SE. These coincide with the macroscopic structural analysis in the field.