准噶尔盆地西北缘构造演化及其与油气成藏的关系

准噶尔盆地西北缘油气资源丰富,但地质结构及演化十分复杂,长期以来一直存在较大争议。本文基于最新勘探进展及区域研究资料,重新梳理了该区的构造变形特征和叠合演化过程,探讨了构造演化与油气成藏的关系。研究认为,准噶尔盆地西北缘具有"东西分带、南北分段、上下分层"的构造特征,二叠纪以来先后经历了早二叠世后造山伸展、中—晚二叠世强烈挤压逆冲、三叠纪继承性逆冲叠加、侏罗纪—白垩纪整体振荡升降和新生代陆内前陆等五大构造阶段,总体上三叠纪前构造活动强烈,三叠纪之后构造趋于稳定。不同地区构造演化过程具有差异性,自北向南3种垂向叠加演化方式形成3类复式地质结构:哈山地区属于"推覆-超剥型",克拉玛依地区属于"逆掩-超剥型",车排子地区属于"冲断-超剥型"。构造演化与油气成藏关系密切,一是不同的叠加演化方式决定了不同的地质结构类型,进而控制不同的源、圈、输导体系等成藏要素及其空间配置关系;二是多期构造活动导致多个成藏期,形成了多种油气成藏模式。准噶尔盆地西北缘经历了多次逆冲抬升,是油气长期指向区,复杂的构造演化导致其具有多源供烃、多期成藏、立体含油的特点。

Tectonic evolution and its relationship with hydrocarbon accumulation in the northwest margin of Junggar basin

Abstract The northwest margin of Junggar basin has abundant hydrocarbon resources, but the geological structure and tectonic evolution are very complicated, with great controversy for a long time. Based on the latest of development exploration and the regional research data, this paper has cleared up the deformation characteristics and the superposed evolution process, as well as explored the relationship between tectonic evolution and hydrocarbon accumulation. The study shows the northwest margin of Junggar basin has the tectonic characteristics of east-west subzone, north-south subsection and vertical stratification. This area experienced five construction phases successively since Permian: Post-orogenic stretch in early Permian, strongly compressional thrust in middle-late Permian, thrust superposed of inheritance in Triassic, oscillating rise and fall overall in Jurassic-Cretaceous as well as the intra continental foreland in Cenozoic. On the whole, this area developed intensive tectonic activities before Triassic and tended to stability after Triassic. There are differences in the processes of tectonic evolution among different area. The three types of vertical superposition of evolution from north to south developed three kinds of complex geological structures. Hashan area belongs to Nappe-Super strip type, Karamay belongs to Overthrust-Super strip type, while Chepaizi area belongs to Thrust-Super strip type. The tectonic evolution and hydrocarbon accumulation have close relationships. Firstly, the different kinds of superimposed evolution determined the types of geological structure, and then controlled different resource, trap, migration pathways and other accumulation elements, as well as the space configuration. Secondly, the multiple tectonic movements resulted many pool-forming periods, and developed many kinds of hydrocarbon accumulation models. The northwest margin of Junggar basin has experienced multi-period of thrust uplift, is a favorable directional zone, the complicated tectonic evolution resulted the characteristics of multiple source for hydrocarbon, multiphase accumulation and three dimensional oil.