缅甸沙林凹陷构造样式及其构造演化

Tectonic Styles and Tectonic Evolution of Salin Depression in Myanmar

摘要: 缅甸沙林凹陷，是缅甸中央盆地西部弧前坳陷带中的次级盆地，盆地内应力作用复杂，且由于缅甸国内研究水平的限制前人对其构造样式与构造演化研究存在不足。本文在总结前人研究的基础上，认为其构造大致经历了伸展断陷—弱挤压—挤压反转—稳定沉积四个主要构造阶段，且选取多条剖面绘制平衡剖面，并估算其伸展率与计算其最大沉积沉降速率，结合地震资料等深部探测资料，对其构造演化特征进行总结，认为沙林凹陷构造样式可以分为伸展、收缩、走滑及反转四种构造样式：伸展构造样式以铲式正断层及叠瓦状断层系为主；收缩构造样式主要为逆冲推覆构造；走滑构造样式以正花状构造为主；反转构造样式是一种叠加构造样式，呈正反转构造特点，剖面上表现为下凹上隆，下正上逆。希望通过对于构造样式的研究来反映盆地的构造演化，可以为之后该地区的油气勘探提供帮助。

Abstract: The Salin depression of Burma is a secondary basin in the front arc depression belt of the western central Burma basin. The stress in the basin is complex. Due to the lack of research on the struc-tural style and tectonic evolution of Burma, the predecessors have studied it. Based on the previous studies, this paper concludes that its structure has undergone three major structural stages: weak extension-stretch extensional-extrusion inversion-stabilization deposition, and a number of profiles have been selected to draw the balanced cross section. And we estimate the extension rate and the calculation of its maximum sedimentation rate, combined with deep seismic data. By summarizing its tectonic evolution characteristics, it is concluded that the structural patterns of Salin depression can be divided into four types: stretching, contraction, strike-slip, and inversion: extensional tectonics with listric normal faults and imbricate faults; contraction structure mainly as a thrust nappe structure; slip tectonic style with positive flower structure; inverted structural style is a kind of superimposed structural style, which is characterized by positive inversion structural features. The section shows that the upper is positive and lower is negative. It is hoped that the tectonic evolution of the basin can be reflected by the study of structural styles, which can help oil and gas exploration in the region.