Inherited discontinuities and Neogene structure: the Gulf of Suez and the northwestern edge of the Red Sea

Abstract

The Gulf of Suez and the northern Red Sea rifts are the result of intracontinental deformation during Neogene times. The initiation and the development of the rift are controlled by (i) four main trends of faults: N140°-N150°; NS to N 20°; sub E -W ; and N40°-60°; (ii) a zigzag faulting pattern; (iii) two main tectonic events. The first is characterized by strike-slip displacements inducing the formation of antithetic tilted blocks. The geometry of the blocks changes according to their orientation. Complex structures can result from the com bination of several trends. Vertical movements are weak. The second is characterized by synthetic normal movements forming a horst and graben pattern. Vertical displacements are important and induce the generation of the axial trough and uplift of the shoulders of the rift. The zigzag pattern of the faults that govern the Rift and the initial strike-slip displacements cannot result from a simple extensional model but imply a reactivation of inherited discontinuities in the Miocene stress system induced by the northern convergent boundaries of the African and Arabic plates. The major trends of faults that control the Neogene structure have been active in this area since Palaeozoic or even Proterozoic times.

The Red Sea and Gulf of Aden Basins

“…Red Sea dikes associated with the rift propagation were caused by rupturing of the lithosphere, and confirm the early extension direction (N60°E). Various models that invoke an early phase of oblique Red Sea extension or pull-apart basin formation (e.g., Jarrige et al, 1986;Hempton, 1987;Makris and Rihm, 1991;Rihm and Henke, 1998) are not supported by the dike orientations or the preponderance of outcrop data (reviewed in Bosworth et al, 1998;Bosworth and McClay, 2001).…”

“…The resulting zigzag pattern of faulting (Fig. 8b) is a fundamental attribute of the northern Red Sea and Gulf of Suez (El Tarabili and Adawy, 1972;Garfunkel and Bartov, 1977;Jarrige et al, 1986;Patton et al, 1994;Bosworth et al, 1998;McClay and Khalil, 1998). On a larger scale, N-S kinks in the N30°W trend of the Nubia Red Sea margin occur at about 15°N, 18°N, and 22°N (Fig.…”

Preliminary seismicity and focal mechanisms in the southern Gulf of Suez: August 1994 through December 1997

“…(1) the main clysmic fault trend (N 40°-30°W), that contains normal faults parallel to the rift axis and created during Neogene times in a pure extensional regime (Said, 1962;Meshref et al, 1976;Bartov et al, 1980;Jarrige et al, 1986;Colleta et al, 1988). (2) Transfer faults with NNE, WNW and ENE trends (Patton et al, 1994).…”

Stress field in the central and northern parts of the Gulf of Suez area, Egypt from earthquake fault plane solutions

“…Two major sets of fault pattern have clearly influenced the rifting processes; the main NW Gulf of Suez trend and the N-S to NNE, ENE, and WNW obliquely oriented trends to it. The Gulf of Suez trend (N50°-20°W) contains normal faults with both pure dip slip (Angelier, 1985) and oblique slip (Lyberis, 1988), parallel to the rift axis and rejuvenated during Neogene times in a pure extensional regime (Said, 1962;Meshref et al, 1976;Bartov et al, 1980;Jarrige et al, 1986;Colleta et al, 1988). The faults oriented obliquely to the Gulf of Suez trend show three main trends, NW oblique (290-310°), N oblique (350-30°) and cross (50-75°) orientations (Patton et al, 1994).…”