摘要
辽东湾坳陷是渤海湾盆地的重要组成部分,其发育受营口—潍坊断裂带控制。其东支的两条分支断层大体沿其次级构造单元辽东湾东部凸起的两侧延伸。本文应用大量地震测线的构造几何学特征分析,结合构造物理模拟试验,认为辽东湾坳陷东部凸起是在先期存在的低凸起的基础上,在渐新世东营组沉积期因营口—潍坊断裂带的右行走滑形成的。以Lz205测线和Lz185测线之间为界可分为类似的两段,各自经历了一个自南而北的右旋走滑伸展—剪切走滑—右旋走滑挤压的变化过程。这种变化由北东向的基底断裂与由之派生的新生代内的北北东内断裂间的关系造成,在两者的交汇点(如Lz151)或走向发生转折处(如Lz255)右旋走滑作用发生变换,其南侧拉张下沉,正断层发育,表现为右旋走滑伸展,北侧则挤压隆升,表现为右旋走滑挤压。南、北两侧相反的力学性质是走滑活动派生的局部差异应力场造成的。构造物理模拟试验证实了右旋走滑伸展—剪切走滑—右旋走滑挤压的变化过程。
The Cenozoic development of the Liaodong Bay Depression, located in northern part of the Bohai Bay Basin, was controlled by the Yingkou-Weifang fault zone. The East Rise, its suborder tectonic unit, was sandwiched in between two branch faults. Based on structural interpretation of several seismic profiles across the Liaodong Bay Depression, the structural geometry characters of the faults on both sides of the East Rise were systematically analysed. The East Rise of Liaodong Bay Depression might come into being on a lower uplift during Oligocene （sedimentary period of the Dongying Formation） , resulted from dextral strike-slipping of the Yingkou-Weifang fault zone. The rise could be divided into two segments, with the seismic lines of Lz205 and Lz185 being a boundary. Each segment showed a change, with their northward stretching, from dextral transextension to shearing, then became a dextral transcompression. The structural segmentation should be caused by varied orientations of the basement fault （NE-striking） and the induced Cenozoic fault （NNE-striking）. In the southern segment, the both of faults converged near the seismic line Lzl51, where the transextention fault to the south of the line changed to shearing then became a transcompression fault. In the southern terminal of the northern segment, the both of faults diverged again and the dextral transextention dominated again. At the seismic line Lz255, the NE-striking fault zigzaged, and corespondingly, the fault changed to strike-slipping and then became a transcompression fault. Our physical modeling experiments repeated the changing of dextral transextention-shearing-dextral transcompression, which confirmed that the mechanical variation and structural segmentation should be resulted from variation of local stress fields induced by dextral strike-slipping of the Yingkou-Weifang fault zone since Oligocene.
出处
《地质科学》
CAS
CSCD
北大核心
2008年第2期238-250,共13页
Chinese Journal of Geology(Scientia Geologica Sinica)
基金
中国石油化工股份有限公司重大油气勘探项目(编号:P03007)的部分成果
关键词
右旋走滑
营口-潍坊断裂带
构造分段
物理模拟
断层几何学
辽东湾坳陷东部凸起
Dextral strike-slip, The Yingkou-Weifang fault zone, Structural segmentation, Physical modeling, Fault geometry, The East Rise of Liaodong Bay Depression
