Pattern of mantle thinning from subsidence and heat flow measurements in the Gulf of Suez: Evidence for the rotation of Sinai and along-strike flow from the Red Sea

We have undertaken a combined analysis of tectonic subsidence, heat flow and uplift data for the Gulf of Suez. Results show significant differences along the length of the rift. The heat flow and subsidence in the northern Gulf of Suez can be fitted by close to uniform extension in the early Miocene with minimal extension since the middle Miocene. In contrast, the southern Gulf of Suez requires that the early Miocene extension is followed by both continuous slow (~1 mm/yr) extension and mantle thinning greatly in excess of the crustal thinning. The continued extension of the southern Gulf of Suez is interpreted as indicating a counterclockwise rotation of the Sinai Peninsula that allows the southern Gulf of Suez to accommodate 10-15% of the motion of the Dead Sea transform. Our best estimate of the net crustal and mantle extension factors for southern Suez are δ=1.4-1.5 and β=2.2-2.6, respectively. While these values are approximate, they indicate a significant input of heat into the southern Gulf of Suez rift that is in excess of that directly advected by extension. Modeling indicates that while ~1/2 of the extension occurred in the early Miocene, most of the lithospheric thinning, and virtually all of the excess thinning of the mantle lithosphere, developed since then. In addition, the Gulf of Suez is bordered by large and growing rift flank uplifts, particularly on the Sinai Peninsula. The geometry of the motions at the Sinai triple junction region has created a large contrast in extension between the Red Sea and Gulf of Suez-Sinai since the middle Miocene. These lateral temperature gradients drove the flow of hot material that is responsible for the extra heating beneath southern Suez and Sinai. The rift flank uplift along most of the Gulf of Suez is interpreted as resulting from a combination of secondary convection and flexure. The much greater uplift in southern Sinai is produced by the additional convective flow from the Red Sea.