黄骅盆地南部前第三系基底中的逆冲构造

Thrust Structure Developed in Pre-Tertiary Basement in South Area of Huanghua Basin

黄骅盆地南部前第三系构造层中广泛发育有逆冲构造 .其中西部的逆冲构造带以逆冲堆叠背形构造和逆冲叠瓦扇构造为主 ,中部以楔冲双重构造和低角度盲冲或顺层滑脱构造为主 ,东部以高角度板状逆冲叠瓦构造为主 .这些逆冲构造带都表现为由SE向NW -MNW方向的逆冲 ,而且由构造样式推测的拆离滑脱深度是由西向东逐渐加深 ,表明在深层可能有一条向南东倾斜的拆离断层将它们连锁在一起 ,构成统一的逆冲构造系统 .从卷入逆冲构造的地层的地质时代推测 ,逆冲构造主要是在早—中三叠世盆地发育之后、侏罗—白垩纪盆地形成之前形成的 ,并在早—中侏罗世盆地发育过程中又有进一步活动 .逆冲构造形成后又受到中—新生代时期的伸展构造和走滑构造的叠加和改造 .控制黄骅盆地老第三纪伸展盆地的形成和演化的沧东断层的某些地段 。

Thrust structure widely developed in pre Tertiary basement in south area of Huanghua basin. There are 6 structural styles in section which includes (1) snakehead and imbricate fan, (2) stack antiform, (3) duplex, (4) blind thrust in low angle or interbeds, (5) triangle zone and (6) high angle thrust domino. In the plane view, there are almost 5 parallel thrust zones striking in NE NNE. The names are given respectively by (1) Cangdong thrust zone, (2) Kongxi thrust zone, (3) Wumaying thrust zone (4) Xuhei thrust zone and Chenxi thrust zone from west to east. In the west part, the thrust structure dominates the styles of snakehead, imbricate fan and stack antiform. In the middle part, the thrust structure dominates the styles of duplex, blind thrust in low angle or interbeds and pop up and triangle zone. In the east part, the thrust structure dominates the styles of thrust domino. Most of the thrust faults are dip to SEE (southeast east) and the structural styles show the detachment of the thrust faults become deeper toward southeast. Possibly, all of the thrusts linked a large scale thrust system whose direction is from SE SEE to NW NWW. The strata involved the thrust system mainly include Paleaozoic group and Lower Middle Triassic but some leading thrusts have put in the Jurassic. We confer the thrust system was formed before Jurassic and after Triassic, and progressive thrust happened during Early Middle Jurassic. The thrust system superposed extensional and right lateral strike slip tectonics during Cenozoic. Some sections of Cangdong fault which was controlling the formation of Huanghua basin during Tertiary were thrust faults during pre Tertiary.