塔里木盆地肖塘南地区断裂构造特征与成因分析

断裂是重要的油气储集空间和渗流通道,是油气地质研究的热点。塔里木盆地发育一系列NE向的走滑断层,其构造演化与形成机制有待深入研究。基于肖塘南地区三维地震资料开展走滑断裂构造特征、形成演化和成因分析。结果表明:①肖塘南地区发育深层走滑断裂、浅层张扭断裂2套断裂系统,深层走滑断裂剖面上为高陡直立或半花状、正花状构造,平面上多表现为线性延伸,断裂交会部分和弯曲部位发育一些分支断层。浅层张扭断裂剖面上为负花状构造,平面上分为NW20°、NE10°、NE30°共3组断层。②研究区断裂经历晚奥陶世走滑断裂、早石炭世张扭断裂2期活动。晚奥陶世走滑断裂为盆地西南缘强烈挤压作用下NE向先存基底薄弱带发生水平位移产生的压扭性走滑断裂。早石炭世张扭断裂是盆地东南缘阿尔金构造域斜向挤压作用下,深层走滑断裂活化产生的同向剪切断层、张性T破裂以及块体旋转产生的分支断层。研究认识对该区奥陶系缝洞型油气藏勘探具有一定的指导意义。

Structural characteristics and formation mechanism of faults in Xiaotangnan area,Tarim Basin,NW China

Faults are important oil and gas reservoir spaces and seepage channels,and faults are hotspots in oil and gas geological research.A series of NE-trending strike-slip faults develop in the Tarim Basin.The structur?al evolution and formation mechanism of these faults need to be studied further.Based on the 3D seismic data in the Xiaotangnan area of the northern slope of Tazhong,the strike-slip fault structure characteristics,formation evolution and mechanism analysis were accomplished.The results are that:(1)Two sets of fault systems,namely deep strike-slip faults and shallow tensile torsional faults,are developed in the Xiaotangnan area.The deep strike-slip fault profile is a high-steep upright or regular flower-like structure,and on the plane,most of them show linear extensions and some branch faults develop at the intersection and the bend.The shallow trans?tensional faults have a negative flower-like structure on the cross section,and they are divided into three groups of faults:NW20°,NE10°,and NE30°.(2)The faults in the study area experienced two phases of activities:Late Ordovician strike-slip faults,and Early Carboniferous transtensional faults.The Late Ordovician strike-slip faults are transpressional strike-slip faults which are generated by horizontal displacement along the NE-pre?served basement weak belts with the strong compression of the southwestern margin of the basin.The Early Carboniferous transtensional faults are syn-shear faults,tensile t-fractures and branch faults caused by block ro?tation which are generated by reactivation of deep strike-slip faults that are closely related to the oblique com?pression from the Algin tectonic domain in the southeastern margin of the basin.The result has certain guiding significance for the exploration of Ordovician fracture?cavity oil and gas reservoirs in this area.