西湖凹陷反转构造分布与样式

Distribution and style of inversed structures in Xihu Depression

西湖凹陷位于东海陆架盆地东部坳陷带,新生代经历了早期裂陷和晚期挤压的构造作用,挤压反转产生一系列反转构造。反转构造样式包括简单反冲反转或Y字型反转构造、地堑式背冲或对冲反转构造、高角度叠瓦状逆冲构造、后断叠瓦式逆冲构造、反冲叠瓦式逆冲构造、"似花状"背冲构造等。凹陷内发育东缘、中央反转构造带、西部斜坡等3个反转构造带。中央反转构造带反转作用最强,东缘次之,西部斜坡最弱。构造反转样式及其动力学过程主要与半地堑断陷陡坡犁形大断裂带的反转有关。

Xihu Depression is located in the eastern depression zone of the East China Sea shelf basin, and has experienced two tectonic movements including the initial rifting and lateral compression during Neozoie Era. A series of inversed structures were formed at that time such as simple inversion and back-thrusting structure or ＂Y＂ style inversion structure, graben like back-thrusting or ramp-thrusting inversion structure, high angle imbricate thrust structure, posthumous imbricate thrust structure, back-thrusting imbricate thrust structure, ＂flower-like＂ back-thrusting structure, and so on. Three kinds of inverted structure zones are well developed in the sag, such as the Eastern Margin, the Central Inverted Structure Zone and West Slope. The strongest inversion happened in Central Inverted Structure zone followed by Eastern Margin and West Slope. The structure inversion styles and its dynamics process are mainly relevant to the inversion of the listric fault zone of the half graben rift steep slope.