钦-杭接合带之构造特征

Tectonic characteristics of the Qinzhou-Hangzhou Joint Belt

华南大陆壳由扬子地块和华夏地块两个主要的地质构造单元组成,其间发育一条板块碰撞拼接带——钦-杭接合带,依据地层组成、构造变形差异,进一步划分为鄣公山构造混杂岩带、绍兴-江山对接带,前者叠加发育在扬子地块南部陆缘江南古岛弧之上,后者代表两地块间消减了的大洋及边缘海混杂体,经历了晋宁—加里东多期碰撞拼贴:晋宁期华夏陆块向扬子陆块俯冲、碰撞、走滑,形成了透镜-网结状韧性剪切系统和三期褶皱变形;加里东运动,华夏陆块再次与扬子陆块碰撞、仰冲,导致华南加里东造山带逆冲推覆在晋宁期造山带之上。至此,两者最终焊接成一体,形成了统一的晚古生代沉积盖层。

The continent of South China is composed of the Yangtze and Cathayian Blocks, with a collision joint belt- Qinzhou-Hangzhou Joint Belt between them. According to their differences of strata and deformations, they can be further divided into subunit, such as the Zhanggongshan tectonic melange, the Shaoxing-Jiangshan joint belt, etc. The Zhanggongshan tectonic melange overprints itself over the Jiangnan ancient island arc on south margin of the Yangtze Block, while the Shaoxing-Jiangshan joint belt represents the subducted ocean land and melange in the marginal sea between two blocks. This belt underwent several collision and joint events from Jinning epoch to Caledonian epoch. During the Jinning epoch, the Cathayian Block subducted toward the Yangtze Block and collided each other, together with a strike-slip event, thus formed a lenticular-reticulation ductility shear zone and three-stage folds. During the Caledonian epoch, the Cathayian Block collided with the Yangtze Block again and thrusted upon the Yangtze Block, inducing the Caledonian orogen of South China thrusted over the Jinning orogen. Thus brought about the final complete amalgamation of the Yangtze Block and Cathaysian Block, giving rise to the unifying South China continent and covered by the Neopaleozoic sedimentary strata.