渤海湾盆地黄骅坳陷中生代构造特征分析

Analysis on Mesozoic tectonic characteristics in Huanghua depression of Bohai Bay basin

渤海湾盆地黄骅坳陷中生代受到印支运动与燕山运动的影响,但因被晚白垩世以来沉积物覆盖,没有很好的露头资料,使得其中生代构造运动的具体特征仍不清楚。基于地震等资料,利用平衡剖面分析以及计算缩短率等方法,分析了黄骅坳陷基底及盖层的构造几何学及运动学特征。根据三叠系、侏罗系、白垩系残余厚度与研究区构造演化剖面等资料,按照中生代构造运动强度将黄骅坳陷分为印支期强挤压区(南部地区)、中生代弱变形区(中部地区)和燕山运动强挤压区(北部地区)。黄骅坳陷中生代主要经历印支运动与燕山运动两期应力方向不同的挤压构造活动,其中印支期鲁西地块向北与黄骅坳陷发生挤压碰撞使得黄骅坳陷南部地区产生了大量逆冲断层,而燕山期燕山褶皱带对黄骅坳陷施加自北向南的挤压应力并促使其在北部地区形成了巨大复背斜。黄骅坳陷南部地区在印支期发生强烈变形,中部及北部地区印支运动响应微弱;燕山运动则正好相反,在黄骅坳陷北部地区活动强烈,在中部及南部地区响应微弱;黄骅坳陷中部地区即孔店-北大港地区构造活动微弱,为两期构造运动波及范围的分界带。中生代变形强烈的区域往往拥有更高的油气勘探潜力,总体上位于黄骅坳陷北部地区的潜山普遍优于位于中南部地区的潜山,而南部地区的潜山则普遍优于中部地区的潜山。本文研究结果对黄骅坳陷下一步潜山油气勘探具有一定的指导意义。

Influenced by Indosinian movement and Yanshan movement,the Mesozoic tectonic evolution in Huanghua depression of Bohai Bay basin is still unclear due to lack of data of outcrops which are covered by the sediments accumulated since the Late Cretaceous.Based on seismic data,this paper analyzed the structural geometry and kinematics of the basement and the cap rock of Huanghua depression by making balanced section and calculating their shortening rate.According to the residual thickness of the Triassic,Jurassic and Cretaceous as well as the tectonic evolution profile of the study area,and referring to the Mesozoic tectonic activity intensity,the depression is divided into the Indosinian strong compression zone(Southern region),the Mesozoic weak deformation zone(Central region)and the Yanshan strong compression zone(Northern region).During the Mesozoic,Huanghua depression mainly experienced the compression tectonic activities of the Indosinian movement and the Yanshan movement which are characterized by different stress direction.During Indosinian,the northward collision of Luxi block with Huanghua depression caused a large number of thrust faults in the southern part of Huanghua depression,while the huge complex anticline in Northern region is the result of the collision between the Huanghua depression and the Yanshanian fold belt during the Yanshanian period.The southern part of Huanghua depression experienced strong deformation during the Indosinian period,and the central and northern regions responded weakly;during the Yanshan movement,the tectonic response was just in opposite situation,with strong activity in the Northern part of Huanghua depression and weak response in the central and southern areas.The central part of Huanghua depression,namely the Kongdian-Beidagang area,had a weak tectonic activity and was a boundary zone between the two tectonic movements.Regions with strong deformation in the Mesozoic era tend to have better exploration potential.Buried hills in the northern part of Huanghua depression are generally superior to those in the south-central region,while the buried hills in the southern region are generally superior to those in the central region.The research results of this paper have some guiding significance for the next step of oil and gas exploration in the buried hills of Huanghua depression.