Surface expression of the Syrian Arc Kattaniya inverted basin in the Abu Roash area, northeast Western Desert, Egypt: Structural style and tectonic history

Abstract

The present study concerns the structural interpretation and tectonic evolution of the Syrian Arc structures of the Kattaniya Basin, northeast Western Desert, Egypt. Published subsurface data on this basin indicates a positive inversion of Jurassic-Early Cretaceous extensional structures during the Late Cretaceous time. In the northeastern part of the Kataniya Basin, the Abu Roash area offers unique and excellent exposures to examine the structural style and constrain any deformational events. Upper Cretaceous strata of the Abu Roash area are deformed by a series of NE-trending left-stepped en echelon oblique folds, which are sequentially dissected by faults of the following development order; ENE- and WNW-trending right lateral wrenches, NE-trending reverse faults, N–S to NNW-trending left-lateral faults and NW-tending normal faults. The Abu Roash area is subdivided into nine structural assemblages locating on both sides of the Cairo-Alex Road. Detailed surface mapping and structural analysis indicate that these structural assemblages were developed throughout a transpressional wrenching mechanism (oblique inversion) with different convergence angles (α = 45° at the northern margin and α = 30° at the southern margin). In summary, the tectonic history of the northeastern segment of the Kattaniya inverted basin is dominated by an extension during the Jurassic-Early Cretaceous times. Such an extension was rejuvenated during the Late Cretaceous as manifested by the angular relationships within Turonian strata of the Abu Roash Formation. This extensional phase was followed by a compressional phase. Tectonic inversion started during the Santonian time, reaching its paroxysm by the Late Senonian. Inversion gradually abated, and there is evidence for complete cessation at the latest Senonian and non-deposition of the Lower Eocene sediments. During the Middle-Late Eocene, this compressional regime had completely ceased. Later during Oligo-Miocene times, the study area recorded a NE-extension and was crossed by NW-trending normal faults. • The Abu Roash area, a surface exposure of the Syrian Arc Kattaniya Basin, is segmented into nine structural assemblages. • The structural elements of Abu Roash area are identified and interpreted. • A mechanism responsible for the development of the nine structural assemblages is proposed. • The tectonic history of Abu Roash area is interpreted based on novel observations.