扬子断块区基底的形成与演化

扬子断块区的躯干主要位于长江流域两侧,向东经江苏滨海穿过黄海南部伸进朝鲜南部。扬子断块区的周界被岩石圈深断裂带所围限,以此与其毗邻的其它大地构造区隔开(张文佑等,1983)。扬子断块区的形成与演化是一个很复杂的地质问题,它经过了漫长的地质历史,包括前震旦纪晋宁地槽发展阶段和震旦纪至第四纪的地台发展阶段,前者形成了断块基底,后者形成断块盖层,盖层与基底之间被区域性不整合面分开。本文主要讨论扬子断块区基底的形成与演化。

THE EVOLUTION OF BASEMENT OF THE YANGZI FAULTING BLOCK

Yangzi Faulting-block region is confined by lithospheric faults on its boundaries with distinct structural characters and geophysical anomalies. Differences in cover rock structural style is to some extent a manifestation of heterogeneity of the basement of this area. The Basement of Yangzi faulting-block region is heterogeneous and can be divided into Yangzi miogeosyncline and Jiang-nan eugeosyncline, showing downstep faulting from north to south, west to east. The heterogeneity of the basement is controlled by lithospheric faults and crust faults and differential movement of faulting blocks. These faults probably formed early in the middle proterozoic ear and controlled or affected the evolution of Yangzi faulting-block region and its vicinities, the structural styles and their development within the faulting block. The. trans formation of Jinn-ing geosyncline into a unified basement of Yangzi faulting block was through polyphase extension and compression.