--> Tectonic Evolution of the Gulf of Aden Rift Margin, Yemen, by K. R. McClay and F. Watchorn; #90986 (1994).

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Abstract: Tectonic Evolution of the Gulf of Aden Rift Margin, Yemen

Ken R. McClay, F. Watchorn

The Gulf of Aden is young passive margin that displays spectacular extensional fault systems along the southern coast of Yemen. The structural evolution of a 300 km long segment of the Gulf of Aden rift margin east of Mukalla, southern Yemen has been determined by detailed field mapping, analysis of Landsat TM and SPOT data combined with seismic interpretation of both onshore and offshore data. Pre-rift strata include crystalline Pan-African basement rocks and a sedimentary sequence of clastics and carbonates that ranges in age from the Cambrian through to the Eocene. Syn-rift clastics and carbonates range from the Oligocene through to the Recent and typically show growth relationships to the extensional fault systems. The rift margin shows extreme topographic relief from the rift sho lder at 2000 m

above sea level to the coast. The rift margin is characterized by a planar seaward-dipping border fault system and domino arrays of landward-dipping antithetic faults. This rift margin polarity is found along the entire section studied. No strike-slip transfer systems were found. Individual extensional faults vary from a few hundred metres to tens of kms in length and display both convex and concave geometries in plan. Displacement transfer between pairs of extensional faults or groups of extensional faults is accomplished relay ramps. Changes in polarity of the individual extensional fault systems within the rift margin are achieved by twist zones and zones of interlocking conjugate faults. Balanced sections incorporating both surface and subsurface data have been constructed across he margin and illustrate the structural styles typical of many rift systems. The 2-D and 3-D fault geometries in the Gulf of Aden rift margin display striking similarities to fault systems developed in sandbox analogue models. A geometric and kinematic model for the tectonic evolution of the Gulf of Aden passive margin is proposed and compared with the evolution of other rifts and passive margins.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994