Structural history of Abu Roash district, Western Desert, Egypt

Abstract

The Abu Roash district is located 10 km to the southwest of Cairo, and is geologically significant because of its surface exposure of Upper Cretaceous rocks. It can be used as a stratigraphic and structural model for the Western Desert. The exposed Upper Cretaceous section is differentiated into two formations, these being the Khoman and Abu Roash Formations seen in the Western Desert penetrations. The Abu Roash Formation has been studied in detail at outcrop and can be directly correlated, both lithologically and paleontologically, with the “A” to “G” members differentiated in the subsurface. The structure of the Abu Roash area is complex with frequent folding and fauting. The faults dissect different rock units of different ages which range from Upper Cenomanian to the Quaternary. They are classified into three categories, normal, reverse and strike-slip faults. The Abu Roash Massif is also characterized by heterogeneous fold styles with different directions. The folds are plunging anticlines and synclines oriented in a NE-SW direction with the exception of the Tel El Mabsuta folds which plunge to the WNW. The northeast trending folds of the area resulted from the combination of compressional stresses iniated from wrenching in addition to arching of the basement. These folds are believed to have developed during the Late Cretaceous - Early Eocene time.