Gravity anomalies in the offshore Safaga area and Red Sea rifting

The Bouguer gravity coverage in the offshore Safaga area of the Egyptian Red Sea shelf, between 26°09′–27°00′N and 34°00′–34°33E′, was investigated by vertical second derivative, analytic upward continuation and subsurface modeling methods to study the basement setup and to investigate probable relationships to the Red Sea rifting.

The second derivative approach delineated narrow Tertiary sedimentary tracts bound by normal Red Sea faulting and showed three traces of probable transverse faulting. The upward continuation indicated broad deep-seated gravity effect which may be related to the upper mantle. Both the derivative and continuation methods showed that the observed transverse gravity gradients may be transverse faults which constitute continuation to mapped shear faults (of repeated movement since the Precambrian) in the continental Safaga. The deep-seated gravity anomaly was found to pass to the well-known positive gravity belt centered over the axial Red Sea zone. The model incident to arching, thinning of crust and subsequent collapse of marginal zones may fit the offshore Safaga area.