Structural mapping and kinematic history of the Qena-Safaga Shear Zone (Egyptian Nubian Shield, East African Orogen)

Abstract

The Qena-Safaga Shear Zone (QSSZ) is a megashear belt separating the Northern-and the Central-Tectonic Provinces of the Egyptian Nubian Shield (ENS). Processing of remotely sensed data of the Landsat-8, ASTER and Sentinel 2A, accompanied by field/structural investigation made it possible to construct a plausible structural map for this high strain zone. A wide variety of Neoproterozoic litho-units outcrop in the area, including ophiolitic mélange, syn-tectonic granitoids, late-tectonic granitoids, Dokhan Volcanics and post-tectonic granitoids. Dike swarms traverse some of these units. The automatic lineament extraction using SRTM and PALSAR images verified that the dominant structural trend is the NE-SW. Other trends, comprising E-W (to ENE-WSW), NW-SE (to NNW-SSE) and N-S (to NNE-SSW) are also recognized. The main structural elements documented in the area embrace foliations and lineations, faults and shear zones, as well as shear zone-related structures (e.g. folds, duplexes and flower structures). The sense of movement along the aforementioned shear trends can be detected by a wide variety of kinematic indicators include mylonite, boudinage structure and deformed pebbles. The geological structures documented along the QSSZ indicate a brittle-ductile tectonic regime accompanied with voluminous granitic intrusions of various composition. Such structural and tectonic setting advocates a complex tectonic history characterized by extensional and transtensional tectonic regimes. The obtained results are significantly contributed to our knowledge on the high strain shear belts in the ENS.