Rift-Stage Evolution of Northern Gulf of Mexico

Joel S. Watkins

Distribution of salt, location of major growth-fault trends, gravity and magnetic anomalies, and deep seismic reflections appear to be related to relict rift-stage basement structures in the northern Gulf of Mexico and Gulf Coast. The basement contains a number of discrete salt basins, probably half grabens, formed during initial rifting. Transform faults trending north-northwest-south-southeast form the sides of the basins. Salt thickness is variable but increases in basins to the east and south. The Corsair fault appears to root in the northern edge of a salt basin, but the surface of the fault crops out over an interbasin high. East-west dislocations of the gravity and magnetic fields coincide with the inferred transform faults; in some cases, linear magnetic anomalies are associated with interbasin highs. Strong deep reflectors are locally associated with basement highs. Overall, the picture appears to be one of north-south rifting, broken by north-northwest-south-southeast-trending transform faults. The overall pattern suggests left-lateral shear.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.