贵州西南部威-紫-罗断裂带构造特征及演化

STRUCTURAL FEATURES AND TECTONIC EVOLUTION OF THE WEI-ZI-LUO FAULT ZONE IN SOUTHWESTERN GUIZHOU PROVINCE

威-紫-罗断裂带作为扬子板块南缘陆内较大的断裂,控制着周围地区的盆地沉积及构造样式。本文通过野外地质勘查、平衡剖面技术及流体包裹体测温,探讨了威-紫-罗断裂带的空间结构特征及构造演化历史。结果显示,NW-SE向威-紫-罗断裂带空间分段特征清楚,运动性质以逆冲和左旋走滑活动为主。流体包裹体测温结果指示该断裂变形环境位于上地壳,以脆性变形为主,温度小于200℃。剖面复原结果显示,断裂带在早泥盆世-中三叠世时期处于引张伸展构造背景下,控制了断裂两侧沉积序列。断裂带挤压变形起始于中三叠世晚期的印支运动时期,强烈变形发生在晚侏罗世早燕山运动时期,与华南地块的向西挤压有关。

The Wei-Zi-Luo fault develops in southwestern margin of the Yangtze block. This is a deep crustal fault zone and controls the deposition and deformation styles of the region. Based on detailed field observations, fluid inclusion analysis and temperature measurements, ＂and using cross section balance, this paper describes structural texture and segmentation feature of the fault zone and discusses its tectonic evolution. The results show that the Wei-Zi-Luo fault zone consists of several segments with kinematics dominated by reverse and sinistral strike-slip motion. Fluid inclusion analysis indicates brittle environment of deformation occurring in the upper crust, with temperature less than 200℃. Restoration of cross section shows that this fault zone was under extension during the Early Devonian to Middle Triassic, which controlled the depositional sequence of the region. It was deformed during the Indosinian orogen at the end of Triassic. The major deformation phase, related to westward push of the South China Block, occurred in Late Jurassic to Early Cretaceous.