伸展盆地中的变换走滑构造及其油气地质意义

    Transform strike-slip structures in extensional basins and their hydrocarbon significance

    • 摘要: 变换构造在伸展盆地内普遍发育,变换走滑构造作为其中的一种特殊类型,是为保持区域或局部应变守恒、传递伸展断层之间的位移,发育在不同伸展断层域之间的具有明显水平位移的被动走滑构造,形成于非走滑应力体制下。变换走滑构造在中国东部伸展盆地中普遍发育、类型多样,依据是否形成明显的走滑断裂可划分为变换走滑断层和变换走滑带,其类型与两侧断层伸展差异大小有关,进一步依据两侧断层的倾向,每类又可划分为倾向相反型、倾向相同型和倾向复杂型3个亚类。变换走滑构造对油气成藏具有重要的控制作用,可以为伸展盆地内构造圈闭解释判识提供依据,变换走滑构造导致了局部地层的弯曲变形,控制了古地貌或微古地貌的分布,进而对沉积储层的发育展布具有一定的控制作用;变换走滑构造可以作为有利的油气聚集区带,也可以对油气分布起到分隔作用。

       

      Abstract: Transform structures are commonly developed in extensional basins. The transform strike-slip structures are passive strike-slip structures with significant horizontal displacement between different extensional fault domains to maintain regional or local strain conservation and transfer displacement between extensional faults, forming under non-strike-slip stress regimes. The transform strike-slip structures are commonly developed in the extensional basins in East China, and could be divided into two major types: transform strike-slip faults and transform strike-slip zones according to whether obvious strike-slip faults formed or not, and their structural styles are related to the difference in extension of faults on both sides. Furthermore, based on the tendency of the extensional faults on both sides, each type could be divided into three subtypes: i.e., opposite tendency, same tendency, and complex tendency. The transform strike-slip structures play an important role in controlling the hydrocarbon accumulation, and provide the base for the explanation and identification of structural traps in the extensional basin. The transform strike-slip structure causes the bending and deformation of local strata and controls the distribution of paleotopography or micro-paleotopography, and controls the development of sedimentary reservoirs. In addition, transformation strike-slip structures can act as favorable zones for oil and gas accumulation, as well as separators for oil and gas distribution.

       

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