Paleostress Analysis of the Brittle Deformations on the Northwestern Margin of the Red Sea and the Southern Gulf of Suez, Egypt

Shear fractures, dip-slip, strike-slip faults and their striations are preserved in the pre-and syn-rift rocks at Gulf of Suez and northwestern margin of the Red Sea. Fault-kinematic analysis and paleostress reconstruction show that the fault systems that control the Red Sea-Gulf of Suez rift structures develop in at least four tectonic stages. The first one is compressional stage and oriented NE-SW. The average stress regime index R' is 1.55 and SHmax oriented NE-SW. This stage is responsible for reactivation of the N-S to NNE, ENE and WNW Precambrian fractures. The second stage is characterized by WNW dextral and NNW to N-S sinistral faults, and is related to NW-SE compressional stress regime. The third stage is belonging to NE-SW extensional regime. The SHmax is oriented NW-SE parallel to the normal faults, and the average stress regime R' is equal 0.26. The NNE-SSW fourth tectonic stage is considered a counterclockwise rotation of the third stage in Pliocene-Pleistocene age. The first and second stages consider the initial stages of rifting, while the third and fourth represent the main stage of rifting.