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Structure of Morgan Hinge Zone, Gulf of Suez, Egypt

Michael H. Garbee, Dana Q. Coffield, Stephen K. Perry, Steven Schamel, John L. Smale

The Morgan hinge zone separates two major segments of the Suez rift containing opposite internal tilt-block rotations. Field studies within the zone's exposed western part show this complex cross-strike structure to be a transfer or accommodation feature, rather than a scissor-faulted hinge system or superimposed, through-going, strike-slip zone. The zone's western part contains complexly faulted and variably tilted blocks with unique histories, in contrast to adjacent orderly tilt-block arrays. Some faults exhibit oblique slip. To the south, the zone terminates against the Esh el Mellaha block, a large, southwest-dipping tilt block. Immediately to the northeast, the Zeit tilt block extends farther northwest and is separated from the adjacent Gebel Gharumul area by a smal , deep pull-apart basin. To the northeast, the hinge zone passes across the rift through Morgan oil field and then doglegs southeastward, ending in a disturbed zone analogous to the Gebel Gharumul area. All fault sets appear to be contemporaneous and have maintained physical continuity.

Local oblique slip and tilting, and high-angle, through-going cross faults terminating in doglegs, associated with deep pull-apart basins, suggest laterally varying transcurrent motion, rather than simple scissor faulting. The continuous border faults preclude through-going, strike-slip faults. Thus, the Morgan hinge zone is a transfer structure forming a decoupled interface between two orderly tilt-block systems. Although strike-slip motions are present locally, they probably cancel out along the entire zone and do not represent regional cross-strike shear.

AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.