Frank Peel1, Gary Cole1, Joe DeVay1
(1) BHP Petroleum Americas, Houston, TX
ABSTRACT: Paleogeographic Evolution of the Deep-Water Frontier of the Gulf of Mexico during the Late Jurassic to Cretaceous; a Radical Reappraisal, and It's Impact on the Petroleum System
Published paleogeographies of the Gulf of Mexico invoke a simple basin history, in which the center of the basin was dropped below sea level by Jurassic rifting and post-rift thermal subsidence. Detailed mapping on recent seismic data sets shows that these models need to be radically reworked. The new data indicate that a Mid-Late Jurassic NW-SE stretching event created an emergent highland area in the present-day basin center. This highland had large-scale asymmetric horst and graben topography akin to the present day Basin and Range province. To the north of this central highland region, a restricted marine basin existed, in which the Louann Salt was deposited.
Oil types support this model: a clastic signature is seen around the margins of the central highland region, focussed at the mouth of a possible drainage system. Further north, away from the margin, a marine marl signature is seen. The rate of subsidence of the highland region increased after a second stretching event, oriented SW-NE. As the highlands became submerged in the Late Jurassic-Early Cretaceous, arcuate island trends developed. These were drowned in the Early Cretaceous, and the deep basin center was established, which has persisted to present day. The tilting of the margin resulted in massive S-SE flow of the Louann salt, and an extensive allochthonous salt front was created by the Early Cretaceous.
The combined effect of all these processes means that the petroleum system in the ultra-deepwater area is very different from that of the mid to upper slope.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado