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Abstract: Large NE–SW oriented asymmetric inversion anticlines bounded on their southeastern sides by reverse faults affect the exposed Mesozoic and Cenozoic sedimentary rocks of the Maghara area (northern Sinai). Seismic data indicate an earlier Jurassic rifting phase and surface structures indicate Late Cretaceous-Early Tertiary inversion phase. The geometry of the early extensional fault system clearly affected the sense of slip of the inverted faults and the geometry of the inversion anticlines. Rift-parallel fault segments were reactivated by reverse slip whereas rift-oblique fault segments were reactivated as oblique-slip faults or lateral/oblique ramps. New syn-inversion faults include two short conjugate strike-slip sets dissecting the forelimbs of inversion anticlines and the inverted faults as well as a set of transverse normal faults dissecting the backlimbs. Small anticline–syncline fold pairs ornamenting the steep flanks of the inversion anticlines are located at the transfer zones between en echelon segments of the inverted faults. [Copyright &y& Elsevier]

Abstract: The Gebel Yelleg area includes a number of folds belonging to the northern Sinai Syrian Arc structures. Detailed surface structural mapping and subsurface (seismic and borehole) data show that the Gebel Yelleg structures are related to Late Cretaceous-Early Tertiary inversion of a Jurassic asymmetric (or half) graben formed during the opening of Neotethys. The inversion structures include a large (45-km long) asymmetric fold (Yelleg Anticline) with a steep flank overlying the southeastern (main) bounding fault of the inverted half graben as well as some right-stepped en echelon folds overlying the northwestern bounding fault of the half graben. The large inversion anticline is dissected by a large number of long, nearly orthogonal normal faults whereas the en echelon folds are dissected by transverse normal faults and two sets of oblique-slip faults. Inversion of the northern Sinai extensional basins is related to Africa-Eurasia convergence and was probably transpressional with a small component of dextral slip. This study shows that the magnitude of inversion in the northern Sinai fold belt decreases toward the southern boundary of the Jurassic extensional province. [Copyright &y& Elsevier]

Abstract: Late Cretaceous–Early Tertiary Syrian Arc folds in northern Egypt include both inversion and non-inversion folds. These folds are well exposed in northern Sinai and the northern Eastern Desert but exist in the subsurface in the northern Western Desert. In northern Sinai, the Maghara, Yelleg, and Halal inversion folds are 45–50 km long. Similar size inversion folds with opposite vergence exist in the subsurface in the northern Western Desert and include the Kattaniya, Mubarak, Alamein-Razzak, and Matruh Basin folds. Smaller non-inversion compressional folds include the Falig and Meneidret El Etheili folds in northern Sinai as well as the Abu Gharadig Anticline in the subsurface in the northern Western Desert; among others. Detailed surface and subsurface structural mapping made use of the excellent exposures and good 2D and 3D seismic data and led to the identification of the fault patterns of the inversion and non-inversion Syrian Arc folds. Inversion folds have fault patterns that differ from the backlimb to the forelimb. The backlimbs are pervasively dissected by long NW-SE oriented normal faults that were formed by the regional stress field. On the contrary, the forelimbs of inversion folds as well as the two limbs of non-inversion folds are affected by the local stress in the folded areas and are dissected by three shorter fault sets; a set of hinge-transverse normal faults and two conjugate sets of hinge-oblique faults that have oblique-slip. The hinge-oblique faults dominate the steeper limbs of asymmetric non-inversion folds. [Copyright &y& Elsevier]