--> ABSTRACT: Longitudinal Evolution of Suez Rift Structure, Egypt, by B. Colletta, P. Le Quellec, J. Letouzey, and I. Moretti; #91030 (2010)

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Longitudinal Evolution of Suez Rift Structure, Egypt

B. Colletta, P. Le Quellec, J. Letouzey, I. Moretti

A three-dimensional study of the structure of the Suez rift has been carried out using field and subsurface data in an attempt to determine the role of transverse faults and the longitudinal evolution of the rift.

As in most intracontinental rifts, the structure of the Gulf of Suez area is governed by normal faults and tilted blocks, whose crests constitute the main target of exploratory wells. The fault pattern consists of two major sets of trends: (1) longitudinal faults parallel with the rift axis and created in an extensional regime, trending east-northeast-west-southwest, and (2) transverse faults with north-south to north-northeast-south-southwest dominant trend. The transverse faults are inherited passive discontinuities, whereas most of the longitudinal faults were created during the Neogene in a purely extensional regime. Both sets were simultaneously active, producing a zigzag pattern and rhombic-shaped blocks. The transverse faults can show horizontal strike-slip components and act a relays between major normal faults.

Although the Suez rift appears as a simple narrow elongated trough dominated by two almost symmetrical shoulders, its internal structure is asymmetrical. Cross profiles show that all the major blocks are tilted in the same direction. However, the tilt direction changes twice along the rift. North and south of the rift, the blocks are titled eastward, but in the central part they are tilted westward. On the north, the change of dip is accommodated by a graben-type "twist zone" without transverse faulting, at least in the Neogene series. To the south, the change of dip is accommodated by a more complex structure involving both a major transverse fault and horst-type "twist zone." In this latter structure, the transverse fault does not cut through the entire rift.

Balanced cross sections established from subsurface data show that the tilt angle and the amount of extension increase from north to south, but the width of the blocks decreases, indicating a pole of opening close to the northern end of the gulf. Minimum values for the amount of opening range between 5 km in the north to about 20 km in the south.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.