大别山南麓大王寨岩体的变形特征及其构造演化意义

SIGNIFICANCE OF DEFORM ATIONAL FEATURES AND TECTONIC EVOLUTION OF DAWANGZHAI INTRUSION IN SOUTH DABIE MOUNTAIN

通过对大别山南麓大王寨岩体的构造变形特征研究,包括面理和线理的测量统计、包体的Rf/φ法研究和带状石英的Robin法应变分析、石英c轴组构分析和微裂隙流态包体面的测定分析,结合化学判别资料,论证了大王寨岩体为新元古代扬子板块与大别微板块碰撞的产物,“东合西开”的连续性碰撞使刚侵位的岩体受到强烈变形,而后的印支燕山运动又对岩体进行了后期改造。岩体的多期构造变形与大别山南麓构造演化以及大别-扬子板块的碰撞过程有着内在联系。

Our study of the structural deformational features of Dawangzhai intrusion with methods such as statistical analysis for foliation and lineation. the method of Rf/φfor enclaves, Robin' s method for ribbon quartzites, fabric analysis for c-axis of quartzites. microscopic analysis for fluid inclusion planes in microcracks, and use of chemical composition discrimination data comfims that Neoproterozoic Dawangzhai intrusion was formed by the collision between Yangtze plate and Dabie microplate. After it took up the location, Dawangzhai intrusion was intensely deformed by the successive collision of the two plates which hinged from east to west. Afterwards, it was reformed during Indo-Sinian and Yanshan movements. Polyphasic deformations in Dawangzhai intrusion are inherently related with the tectonic evolution in South Dabie Mountain as well as the collisional processes of Dabie-Yangtze plates.