塔里木盆地塔中隆起走滑断裂的三层结构模型及其形成机制

塔中隆起位于塔里木盆地中央隆起带中部，为塔里木盆地油气勘探的重点区块之一。以塔中隆起高品质三维地震资料精细解释为基础，开展塔中隆起走滑断裂的剖面和平面几何学特征、断裂的活动期次和断裂形成机制研究。地震资料显示塔中走滑断裂于石炭纪之前定型，少数走滑断裂的活动持续到了石炭纪之后，断穿基底到志留系和泥盆系，断面直立，但是在不同层位断层的几何特征存在明显差异性，主要分为3层结构：深层中、下寒武统断裂平面上呈线性展布，中、下寒武统在断裂两侧上拱；深部断裂向上继续切穿上寒武统和奥陶系，并在碳酸盐岩顶面发育许多分支断裂，剖面上表现为正花状构造，平面上组合为斜列断裂；浅层走滑断裂发育在上奥陶统-志留系和泥盆系内，剖面上常以负花状构造样式出现，平面上表现为该层特有的北西向雁列断层。这3层断裂在垂向上叠置，形成复杂的空间形态，将塔中隆起走滑断裂的演化阶段划分为3期：中寒武世塔中地区存在构造反转事件，在压扭应力作用下发育规模较小的走滑断裂；晚奥陶世走滑断裂复活，形成正花状构造；志留纪—泥盆纪走滑断裂持续活动。塔中隆起走滑断裂的形成受周缘构造环境控制，在中寒武世局部压扭应力、晚奥陶世压扭环境和志留纪—泥盆纪的压扭环境下形成演化。

Three-layer structure model of strike-slip faults in the Tazhong Uplift and its formation mechanism

The Tazhong uplift located in the central uplift zone of Tarim Basin， is one of the key oil and gas plays in the Tarim Basin. A detailed interpretation of high-quality 3D seismic data， is applied to study the geometry characteristics of the strike-slip faults on both plane and sectional views， active periods of faulting and its formation mechanism in the Tazhong Uplift. Seismological data show that activity of most strike-slip faults in Tazhong uplift finalized before the Carboniferous， and only a few still kept active after the Carboniferous. The strike-slip faults cut through the strata from the basement to the Silurian and Devonian systems with vertical fault planes， which are obviously different from each other in geometry as in a three-layer structure. The fault planes in the deep Middle and Lower Cambrian feature linear distribution， with the strata on both sides of the fault arching. Multiple branch faults are developed on the top surface of carbonate rock after the strike-slip faults growing upward into the Upper Cambrian and Ordovician， as shown in a positive flower-like structure on sectional view， and by a diagonal fault pattern on plane view. While the strike-slip faults in the shallow Upper Ordovician， Silurian and Devonian systems commonly appear as a negative flower-like structure on sectional view， and as NW-trending en-echelon faults on plane view， specific to this layer. These three-layer faults are superimposed vertically in a complex spatial pattern. The evolution of strike-slip faults in the Tazhong Uplift is divided into three stages， that is， the Middle Cambrian when a structural inversion event led to the development of small-scale strike-slip faults under transpressional stress； the Late Ordovician when the strike-slip faults got reactivated to form a positive flower-like structure； and the Silurian and Devonian during which the strike-slip faults kept active. The development of the strike-slip faults in the Tazhong Uplift can be attributed to the control of peripheral tectonic environment and evolution under the local transpressional stress in the Middle Cambrian， the transpressional setting in the Late Ordovician， Silurian and Devonian.