SURFACE AND SUBSURFACE STRUCTURAL SETTING OF THE AREA EAST AND SOUTHEAST OF THE SOUTH GALALA PLATEAU

Abstract

The study area represents the southwestern part of the Gharandal accommodation zone in the Suez rift.. This zone separates the northern (southwest dipping) half graben from the central (northeast dipping) half graben. The study area includes two parts which are surface and subsurface parts. The surface part occupies the western side of the Suez rift in the area between Wadi El-Dahal and Gebel Thelemet whereas the subsurface part lies to the northeast of it. The structural style of the study area is mainly controlled by faults. Some folds, however, are observed in the study area. These structures affect most of the rock units that range in age from Precambrian to Recent. The faults in the study area exist in three main sets. These sets are the NNW fault set (Clysmic trend), N-S fault set and NNE fault set. The Clysmic faults in the study area are the longest and have the largest displacements and they were formed by northeast oriented extension during the initial stage of Suez rifting in Oligo-Miocene time. The Clysmic faults splay into north­ northeast or north-south oriented faults. Different types of transfer zones are found and described in the study area. The rotation on the listric planes of some ofthe Clysmic faults in the study area formed several domino-style tilted fault blocks. The tilted fault blocks are herein called the Southern Galala block, El­ Dahal block, Abu Rarnith block, Abu Khalifi block, East Thelemet block, Zaafarana block and Central Gulf block. In the subsurface part of the study area, the northeast dip direction dominates in the southern part of the Zaafarana block and the southern part of the Central Gulf block. On the other hand, southwest dip direction can be found in the northern part of the Zaafarana block and the Central Gulf block. Thus, the northeast and southwest dip domains intermix in the central part of the Zaafarana block. Only north and south of the Gharandal accommodation zone one is able to recognize a single predominant direction of dip. In the surface part of the study area, the two dip directions are also found