STRUCTURAL EVOLUTION AND PETROLEUM SYSTEM OF THE MESOZOIC FAGHUR RIFT BASIN AT THE NORTHWESTERN DESERT OF EGYPT

Document Type : Original Article

Authors

1 Apache Egypt Companies.

2 USA

3 Geology Department, Faculty of science, Cairo uniersity

Abstract

The Faghur Rift Basin (FRB) is a Jurassic to Cretaceous asymmetric extensional rift located in the far west of the Northwestern Desert of Egypt and has a considerable petroleum potential, first discovered in 1989. This work proposes a structural evolution scenario for the FRB based on the results of 3D seismic interpretation, borehole data and 1D-basin model. The FRB is bounded to the north by a major E-W striking, extensional, multi-history, basin bounding fault system where the Jurassic and the most Early Cretaceous succession are missing in the upthrown Waha platform. To the south, the whole succession is present where four major Mesozoic tectonic phases during the rift history were recognized through the FRB evolution as follows: 1) The Late Jurassic rift initiation phase which was expressed by the deposition of the earls syn-rift sequence of Khatatba clastics in four localized E to ENE-striking extensional half-grabens and ended by a marine transgression and the deposition of the Masajid limestone, 2) The Valanginian to Hauterivian/Early Barremian main rift phase which had rapid subsidence and deposition of the laterally complex siliciclastics syn-rift sediments of Alam el Bueib Member. A second regional transgression occurred in the early Aptian resulted in the Alamein carbonate deposition. 3) The third rift phase of Aptian to Albian time deposited the syn-rift siliciclastics of Kharita Member and continued with the deposition of Bahariya Formation in the Early Cenomanian 4) The fourth rift phase; during the Turonian-Santonian and was expressed by the deposition of limestone and shale of the Abu Roash Formation.
During the first and second phases, Late Jurassic-Early Barremian, the extension direction was mainly due the N to the NNW, resulted in E-W to ENE-WSW extensional faults.
By the end of the second phase, mainly post Alamein or late Aptian, the extension direction rotated to the NE, and continued to the end of the fourth phase to cause superimposing of a younger NW-SE extensional faults on the older E-W fabric.
Thermal sag was determined during the Campanian-Tortonian, the FRB was distinguished by a widespread and long-lived carbonate deposition.

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