全球变化知识资源中心

A low-to medium-grade metamorphic belt of a volcano-sedimentary succession occurs in the eastern side of South Sinai as a part of the northernmost extension of the Arabian–Nubian Shield in Egypt. The belt is known as the Kid metamorphic complex. It is considered as one of the major belt among the other exposed metamorphic belts in South Sinai. Here, we detect and investigate the signature of the Najd Fault system in South Sinai based on detailed structural analysis in field and digital image processing. The enhanced satellite image and the geo-spatial distributions confirm that the Kid belt is essentially composed of nine Precambrian units. Field relations and geometrical analysis of the measured structural data revealed that the study area underwent four successive deformational phases (D1–D4). D1 is an upright tight to isoclinal large-scale folds that caused few F1 small-scale folds and a steeply dipping S1 axial plane foliation. The second deformational event D2 produced dominant of sub-horizontal S2 foliation planes accompanied with recumbent isoclinal folds and NW–SE trending L2 lineations. The main sense during D2 was top-to-the-NW with local reversals to the SE. The third folding generations F3 is recorded as axial plane S3-surfaces and is characterized by open concentric folding that overprinting both F1 and F2 folds and has a flexural-slip mechanism. F3 fold hinges plunge to the west–northwest or east–southeast indicate north–northeast–south–southwest shortening during D3. The fourth deformational event D4 is characterized by NE plunging open concentric folding overprint the pre-existing fold generations and formed under flexural slip mechanism reflecting coaxial deformation and indicating change in the stress regime as a result of the change in shortening from NE–SW to NW–SE. This phase is probably accompanied with the final assembly of east and west Gondwana. The dextral NW–SE shear zone that bounded the southwestern portion of the metamorphic belt is probably related to reactivation of the Najd fault system during Oligo-Miocene in South Sinai. © 2017, Springer-Verlag Berlin Heidelberg.