准噶尔盆地莫索湾凸起构造演化动力学

Dynamics for Mosuowan Uplift Structural Development in Junggar Basin

隆起构造是沉积盆地内的大型正向构造单元,是油气聚集的主要场所。由于沉积盆地的多旋回叠加演化,隆起的形成发育表现为复杂的动力学过程。隆起在沉积期、(油气)成藏期、调整期与定型期具有不同的地质结构,决定了油气形成、聚集与分布的地质环境,因此,隆起构造演化动力学是含油气盆地构造分析的核心。从古构造分析的角度,解析了准噶尔盆地莫索湾凸起的构造演化史。莫索湾凸起是在石炭纪“基底”隆起的背景上,经二叠纪构造运动发育起来的大型隆起构造;在经过三叠纪—中侏罗世西山窑组沉积期的稳定沉降与埋藏之后,在中侏罗世晚期—晚侏罗世遭受强烈改造;其后,在早白垩世再次稳定沉降,晚白垩世—古近纪发生“振荡”运动,在新近纪随着南侧昌吉坳陷的急剧挠曲沉降而发生向南倾斜。莫索湾凸起经历了雏形期、发育期、埋藏期、改造期、调整期与定型期等6个地球动力学阶段的演化,现今成为深埋藏的大型背斜,具有优越的成藏条件。

Uplift structure is the large-scale positive structural unit in the sedimentary basin. It is the main place for oil and gas accumulation. Formation and development of uplift is a complicated dynamic process owing to the multi-cycle superimposed development of the sedimentary basin. The different geological structures in the different stages of the uplift, such as , the sedimentary stage, the (oil and gas) migration and accumulation stage, the adjustment stage, and shaping stage, determine the geological environment for oil and gas generation,migration, accumulation and distribution. Therefore, the dynamics for uplift structural development holds the key to analysis of oil and gas basin structure. From the view of palaeostructural analysis, this paper analyzes the structural evolutional history of Mosuowan Uplift in Junggar Basin. Mosuowan Uplift is a large-scale uplift developed under the background of the Carboniferous 'basement' uplift and subject to the Permian structural activities. The uplift comes under strong remoulding from the later period of Middle Jurassic to Late Jurassic after the stable subsidence and burial in the Xishanyao Formation sedimentary period in Triassic-Middle Jurassic. Afterwards, the uplift has experienced another stable subsidence in Early Cretaceous and the oscillatory activities in Late Cretaceous to Early Tertery, and in Later Tertery started to tilt southward with the rapid subsidence of Changji Sag on the southern side. Mosuowan Uplift has gone through six geo-dynamic development stages - preliminary stage, development stage, burial stage, remoulding stage, adjustment stage and reshaping stage. It currently becomes a large-scale anticline with the large buried depth. It has the superior conditions for hydrocarbon accumulation.