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Abstract: The Geological Evolution of the Deep Water Perdido Foldbelt, Alaminos Canyon, Northwestern Deep Gulf of Mexico

Bruce D. Trudgill, Joseph C. Fiduk, Paul Weimer, Mark G. Rowan, Peter E. Gale, Bryant E. Korn, Ronald L. Phair, William T. Gafford, James B. Dischinger, Geneva R. Roberts

The Perdido Foldbelt, lying in the NW part of the Gulf of Mexico basin, is defined by a series of large-scale fold structures that extend SW into Mexican waters and NE beneath the well-defined Sigsbee Salt Escarpment. Within the Alaminos Canyon area, the foldbelt consists of a series of NE-SW trending, sub-parallel, concentric, box folds cut on one or both of their flanks by high-angle reverse faults.

Detailed structural mapping and cross section restoration have produced a model for the structural evolution of the Perdido Foldbelt that is consistent with seismic stratigraphic analysis of the data. The main phase of compressional deformation in the Perdido Foldbelt occurred during the Oligo-Miocene by gravity sliding on a detachment at the top of the Jurassic Louann salt sequence. The overall geometry of the foldbelt indicates that autochthonous salt thicknesses are highly variable, possibly related to basement structural highs and lows. Middle to Upper Miocene strata onlap the folded sequences, with further Pliocene to present-day uplift possibly a result of either active diapirism of the salt-filled cores of the highest-relief structures, or contractional reactivation of the fold and/or faults. Gravity slides off the crests of the folds are common within the younger sequences, resulting in a complex fault geometry in the higher parts of the folds.

With more than 7000m of strata involved in the foldbelt structures, the presence of both reservoir and source horizons within the section is predicted. On the basis of correlations with deep Gulf of Mexico sequences, folded strata include Upper Jurassic through Oligocene age rocks. Anticipated reservoir horizons include Lower Cretaceous forereef debris deposits, Upper Cretaceous Chalk, and Lower Tertiary turbidite sandstones.

AAPG Search and Discovery Article #90955©1995 GCAGS 45th Annual Meeting and Gulf Section SEPM, Baton Rouge, Louisiana