渤海湾盆地中部中生代多幕构造变形及其形成机制

Mesozoic multistage deformation and mechanism of the Central Bohai Bay Basin formation

  • 摘要: 为揭示渤海湾盆地中部印支期与燕山期多幕变形的构造特征及演化过程,为潜山油气勘探提供理论支持,本文基于研究区三维地震资料的详细构造解析,厘定了研究区中生代的地层划分、构造变形序列及晚期变形对早期变形的叠加改造过程,并探讨了各阶段构造变形的形成机制。结果表明:渤海湾盆地中部在中生代期间主要发育三组断层,其中印支运动表现为自南向北的逆冲推覆,形成NW-近EW向叠瓦式逆断层,其在晚侏罗世-早白垩世期间发生负反转活动,而该时期形成的NNE-近SN向的捩断层调节了不同块体之间的差异运动。燕山运动在研究区主要表现为中侏罗世末和晚白垩世的两幕NW-SE向挤压,形成了NE-SW向逆断层,其局部继承印支期断层面活动,而印支期捩断层在燕山期演变成压扭性的左行走滑断层,并约束了NE向逆断层的规模。

     

    Abstract: Revealing the structural characteristics of multistage deformations and evolution of the Central Bohai Bay Basin during the Indosinian and Yanshanian could provide theoretical support for oil and gas exploration of buried-hills. Based on a detailed structural analysis on the 3D seismic data in the study area, we determined the stratigraphic division, tectonic sequence, and superimposed modification of late deformation on early one, and analyzed the mechanism of the deformation in each stage. The Central Bohai Bay Basin developed three main groups of faults in the Mesozoic. The Indosinian Movement triggered northward thrusting, forming NW to nearly EW-trending imbricated thrust faults that underwent negative inversion during the Late Jurassic to Early Cretaceous. The NNE to nearly SN-trending tear faults formed during the Indosinian regulated the movement among different blocks. The Yanshanian Movement evidenced two episodes of NW-SE compression during the late Middle Jurassic and Late Cretaceous, respectively. The compression formed NE-SW-trending reverse faults of which some parts inherited Indosinian fault plane. In addition, the Indosinian tear faults evolved into transpressional sinistral strike-slip faults in the Yanshanian, constraining the scale of the NE-trending reverse faults.

     

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