Two-stage wrench deformation at Gebel El Minsherah, north Sinai

Abstract

Detailed field mapping and structural study of the Gebel El Minsherah area show the effect of ENE oriented strike-slip faults on the structural deformation of this area. Two stages of right-lateral wrenching are evident in this part of north Sinai. The first stage of deformation proceeded via right-lateral convergent wrenching and is apparently related to the Late Cretaceous-Early Tertiary oblique convergence between Africa and Eurasia and the closure of the Tethys as reported in previous studies. This deformational event formed the Minsherah ridge anticline by drag of the hanging wall of the Minsherah (right-lateral reverse) fault. It also formed an anticline in the central part of the area (between the Minsherah ridge and the Wadi El Hasana trap-door structure). This fold is a push-up structure related to the right-lateral strike-slip movement on the Minsherah and Wadi El Hasana faults. Missing section at the base of the Upper Senonian chalk defined a local unconformity at the north western flank of this anticline and dates the first stage of deformation of the G. El Minsherah area. The second stage of wrenching in the area is post-Early Miocene as indicated by 120 meters dextral offset of a Lower Miocene basic igneous dike by the Rishat Lehman fault. The other ENE oriented faults were rejuvenated during this stage. A pull-apart graben is formed between the Rishat Lehman fault and the westernmost part of the Minsherah fault. The right-lateral wrenching of this stage is kinematically compatible with the NE-SW extension in the Suez rift and central Sinai.