Distribution of Crust in Deep Eastern Gulf of Mexico

David B. Rosenthal, Richard T. Buffler, William P. Corso, Paul Weimer

Most current models for the evolution of the Gulf of Mexico suggest that Upper Jurassic oceanic crust underlies the deep part of the basin, surrounded by older, attenuated continental crust (thin transitional crust). Based on a detailed analysis of existing University of Texas Institute for Geophysics multifold seismic reflection data and a recently available grid of industry data, we have redefined the oceanic/transitional crust boundary as well as characterized and mapped basement trends in areas of oceanic crust in the deep eastern gulf. Along the eastern part of the study area, the crust boundary is defined where Middle Jurassic(?) salt and equivalent strata, deposited on transitional crust prior to the emplacement of oceanic crust, onlap and pinch out basinward onto basement block. In the northern and southern parts of the study area, the boundary is obscured by low-relief salt tongues. Regional basement highs and lows associated with oceanic crust within the central part of the deep eastern Gulf trend east-northeast-west-southwest. Deep marine rocks overlying oceanic crust appear to onlap both north and south onto a median high, suggesting that this linear feature may represent a segment of an extinct mid-ocean spreading ridge. A north-northwest-striking trough perpendicular to and bisecting the median ridge could represent an extinct fracture zone. These trends indicate that in the central gulf, sea-floor spreading was probably in a north-northwest-south-southeast direction. Apparent lack of regional structural trends in the eastern part of the s udy area, however, suggest a different origin for this part of the oceanic crust. These boundaries are structural trends provide important constraints for Gulf of Mexico reconstructions.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.