--> ABSTRACT: Accommodation Structures on Morgan Hinge Zone, Gulf of Suez, Egypt, by Stephen K. Perry and Steven Schamel; #91030 (2010)

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Accommodation Structures on Morgan Hinge Zone, Gulf of Suez, Egypt

Stephen K. Perry, Steven Schamel

The Morgan hinge zone is a narrow, complex structural belt separating a province of southwest-dipping fault blocks in the southern Gulf of Suez from a northeast-dipping province in the central Gulf. The variety of accommodation structures within this zone appears to result from the intersection of oppositely dipping, low-angle extensional detachments underlying the two dip provinces.

The central and the southern Gulf provinces both exhibit similar gross morphologies. An array of similarly tilted fault blocks extends from one margin of the rift to close to the opposite margin, where dips of the tilt blocks decrease, then reverse, forming a broad structural arch adjacent to the border fault. This structural pattern results from extension on a low-angle master detachment having a dip opposite to that of the overlying tilt block array. Thus, the central Gulf province appears to have opened by extension on a southwest-dipping detachment, whereas the southern Gulf province opened on a northeast-dipping detachment. The accommodation zone bounding the two dip provinces contains structures formed in response to volumetric constraints in the region bounding the oppositely d pping master detachments.

Three major accommodation structures link to form the Morgan hinge zone. Transverse arches project outward from both rift margins. In the west, near Ras Shukheir, a gently dipping platform breaks northward into an array of small cross-strike tilt blocks but is truncated on the south by a broad, arcuate cross fault with major throw. In the central Gulf, a series of arcuate normal faults form spiraling splays around the broad dome at the Morgan field. The factors controlling the accommodation structures are (1) the configuration of the master detachments adjacent to the accommodation zone, (2) the vertical separation between the two opposing master detachments, and (3) preexisting mechanical weaknesses within the prerift basement terrane.

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