Superposed deformation in the northern Suez rift, Egypt: Relevance to hydrocarbon exploration

Abstract

Detailed subsurface study of the northern part of the Suez rift and adjacent areas indicates the superposition of two different deformations. During the earlier (Late Cretaceous) deformation, folds with NE-SW oriented axes were formed in northern Egypt as a result of the convergence between Africa and Eurasia and closure of Neotethys. During the later (Early Miocene) deformation, NW oriented normal faults were formed as a result of the opening of the Suez rift. Borehole data have shown that a belt of northeast oriented en echelon folds exists in the subsurface in the northernmost part of the rift between Ayun Musa and the Sukhna-1 well, south of Gebel Ataqa. This fold belt represents the southwestern continuation of the en echelon folds exposed in the Mitla Pass, to the northeast of the rift. Another pre-rift structure is the offshore extension of the Wadi Araba structure as a southeast-facing monocline. This offshore structure also represents the continuation of the Gebel Somar structure, eastern shoulder of the Suez rift. The Gebel Somar and Wadi Araba structures represent the southernmost pre-rift folds in northern Egypt. Pre-rift folds in the study area stood high above the Paleocene and Early Eocene sea levels. Upper Cretaceous and/or older rocks in the cores of these folds were later unconformably covered by Middle Eocene rocks. The presence of Late Cretaceous folds should be taken into consideration when exploring for hydrocarbons in this part of the Suez rift. Borehole data in the northeastern part of Egypt also indicate the presence of Late Cretaceous folds underneath the almost flat-lying Tertiary rocks in the northern part of the Eastern Desert. These folds are considered potential hydrocarbon traps in a relatively poorly explored area.