济阳坳陷中-新生代断裂发育特征及形成机制

济阳坳陷中生代以NW向断裂活动为主;新生代早期盆地发育受NW向和NE向断裂共同控制,沙河街组四段沉积后,以NE向断裂活动为主。济阳坳陷中-新生代断裂活动主要受太平洋板块向欧亚板块的斜向俯冲造成的弧后伸展作用及郯庐断裂的走滑作用联合控制。早白垩世初,太平洋板块向欧亚大陆的俯冲使郯庐断裂带发生左行走滑平移,在济阳地区形成了一系列NW向正断层。新生代早期,济阳坳陷东部断裂活动受郯庐断裂左旋走滑的控制,而西部受弧后伸展作用影响较大。大约43 Ma后,太平洋板块聚敛方向改变,济阳坳陷断裂活动主要受NW-SE向区域伸展作用控制。

Characteristics and formation mechanism of the faults in Mesozoic-Cenozoic in Jiyang Depression

Dominated by NW-trending faulting during the Mesozoic and jointly controlled by NW- and NE-trending faults in the Early Cenozoic, Jiyang depression was then governed by NE-trending faulting after the deposition of 4th Member in the Shahejie Formation. The faulting in Jiyang depression in Mesozoic-Cenozoic was jointly controlled by back-arc spreading resulted from the oblique subduction of the Pacific plate towards the Eurasia plate and the strike-slip movement of the Tanlu fault zone. A series of NW-trending normal faults were formed as a response to a sinistral strike slip of the Tanlu fault belt during the Early Cretaceous. In the Early Cenozoic, faulting in the eastern Jiyang depression was controlled by the sinistral strike slip of the Tanlu fault belt, while in the western part of the depression, it was mainly affected by the back-arc spreading process. After about 43Ma when the convergence direction of the Pacific plate changed, the faulting in Jiyang depression was mainly controlled by the NW-SE trending regional spreading process.