叠合盆地差异构造变形与油气聚集

Differential deformation and hydrocarbon accumulation in the superimposed basins

文中探讨叠合盆地差异构造变形特征及其对油气聚集的控制作用。叠合盆地差异构造变形受控于多期构造演化导致的多期构造应力场转换、多种变形介质变化以及多方位边界条件的变化,主要表现为:(1)受关键构造变革期应力场转换制约的分期差异构造变形,早期一般受区域伸展作用形成垒-堑构造,中期由于板块聚敛活动形成冲断滑脱和潜山-披覆构造,晚期在叠置的前陆盆地形成褶皱-冲断带;(2)受大型主断裂带控制的分带差异构造变形,这些大型主断裂带一般与先存基底断裂或基底软弱带有关,不同构造带的变形强度呈有规律变化;(3)受多层次滑脱带控制的分层差异构造变形,深层次滑脱构造变形主要表现为与盆山耦合有关的滑脱拆离变形,中层次滑脱构造表现为基底层系的滑脱拆离,浅层次滑脱构造表现为与盐膏岩或泥页岩有关的塑性构造变形;(4)受构造转换带控制的分段差异构造变形,区域性转换带本身常成为重要的横向构造带,不同构造段之间变形样式和运动学过程具有较大差别,局部构造转换带往往形成有利的油气圈闭。差异构造变形与烃源岩发育、油气成藏期、圈闭形成演化、油气藏形成和分布及油气保存条件密切相关。

The purpose of this paper is to describe the characteristics of the differential deformation in superimposed basins and its control over the hydrocarbon accumulation. The differential deformation of superimposed basin is controlled by poly-phase stress field transition, varied deformation medium, and various basin boundaries. The major characteristics of differential deformation are as follows. （1） Poly-phase differential deformation controlled by the key tectonic movement and stress field transition. The horse-graben structures are formed under the regional extensional regime at the early stage; the detachment structures and buried hill-drape assemblages are generated relating to the convergent margins at the medium stage; the fold-thrust belts are originated in the overlying foreland basins at the later stage. （2） Zonal differential deformation controlled by major fault belts is related to pre-existing basement weak zones. The deformation intensity changed regularly in various structural zones. （3） Multi-level differential deformation controlled by decollement zones. The deeP-level detachment structures are associated with basin-range coupling; the medium-level detachment structures are related to basement decollement layers, and the shallow-level detachment structures may have a bearing on plastic deformation associated with the salt bed or argillutite. （4） Segmental differential deformation controlled by transfer zones. The structural styles and kinematics may have a great difference in different segments because of the large-scale transfer zones. The local transfer may form favorable oil-gas traps. The differential deformation may be closely related to the development of source rocks, the hydrocarbon accumulation epoch, the trap evolution, the distribution and preservation of oil-gas pools.