Overview on the subsurface structure-tectonic controls in the northwest Bahariya, Western Desert, Egypt

Abstract

A regional structural investigation was done on the northwestern part of Bahariya Oasis, using the potential field maps aided by geo-seismic sections and wells data. The gravity and magnetic maps were reinterpreted in context of geotectonic evolution of the north Western Desert to throw more light on the source of subsurface structures. Several processing methods and filtering techniques were applied to delineate locations, trends and depths of main source structures. Qualitatively, the study indicates that Bahariya horst is the highest in gravity, Sitra platform has the strongest magnetism, whereas Misawage graben is the largest in depth to the basement surface. The results were integrated to construct a tentative tectonic map, which exhibits an older folding in the NW direction intersected by a younger ENE trend, which seems to be crossed by a set of NW-trending faults. The map underlines regional folding in NE-SW trend (Syrian arc), forming four major structural features (Misawage graben, Sitra platform, Bahariya uplift and Dirrut basin), each has distinctive characteristics. The tectonic model suggests two different forces (NNW-compression and ENE-tension) affected the area, forming two main fold trends and five cycles of deformation. The models indicate a rough basement surface with a regional dip regime toward the north, overlain by a sedimentary cover ranges between 1 and 4.5 km in thickness. The basement is generally of acidic composition with some basic intrusions penetrate the boundary faults.