The Abu El Gharadiq Basin (AGB) is one of the largest Cretaceous rift basins in the northern district of the Western Desert of Egypt. The AGB underwent tectonic inversion in the Upper Cretaceous through horizontal shortening in the NW-SE direction. Detailed interpretation of seismic sections across discrete regions of this basin shows that the rocks deformed in two different depth-related deformation styles, which are partitioned across the base of the so called Bahariya Formation of Cenomanian age. The deeper, pre-Cenomanian rock units show contractional deformation forming tight folds and related fabrics while shallower, post-Cenomanian rock units display features of extensional deformation. These are essentially shallowly undulating open folds, associated with conjugate normal faults and tensional fractures. The deeper pre-Cenomanian tight anticlines pierce the upper rock units as diapiric-like intrusions that are seen on the seismic sections as hazy regions. We infer that the two different deformation styles above and below the Cenomanian rocks occurred simultaneously. The hazy regions on the seismic sections may result from lateral flow of shale rocks that give rise to chaotic structures near the anticlines. Mechanical anisotropy across the Cennomanian rock unit is inferred to be the main cause of simultaneous emergence of contractional and extensional deformations. Re-evaluation of fracture patterns of the northern rift basins in the Western Desert implies that the AGB originated in an extensional stepover region of a discrete, ENE-WSE trending, shear zone whose margins underwent inversions, developing two parallel thrust-dominated ridges, namely the crustal scale Kattaniya and Qattara-Alamein ridges.

Abu El Gharadiq 盆地 (AGB) 是埃及西部沙漠北部地区最大的白垩纪裂谷盆地之一。AGB 在上白垩统通过 NW-SE 方向的水平缩短经历了构造反转。对该盆地离散区域的地震剖面的详细解释表明，岩石以两种不同的与深度相关的变形方式变形，它们分布在所谓的 Cenomanian 时代的 Bahariya 组的底部。较深的前森曼阶岩石单元显示收缩变形，形成紧密褶皱和相关结构，而较浅的后森曼阶岩石单元显示拉伸变形特征。这些基本上是浅浅起伏的开放褶皱，与共轭正断层和张性断裂有关。更深的前森曼阶致密背斜刺穿上部岩石单元，作为底辟似的侵入体，在地震剖面上被视为朦胧区域。我们推断森诺曼阶岩石上下两种不同的变形方式同时发生。地震剖面上的朦胧区域可能是由于页岩岩的侧向流动导致背斜附近的混沌结构。整个 Cennomanian 岩石单元的机械各向异性被推断是收缩和拉伸变形同时出现的主要原因。对西部沙漠北部裂谷盆地断裂模式的重新评估表明，AGB 起源于一个离散的、ENE-WSE 趋势的剪切带的伸展跨区，其边缘经历了反转，形成了两条平行的逆冲脊，