--> The Variable Age of Decollement Surfaces in the Gulf Coast of Texas and Louisiana, by R. O. Brooks; #90986 (1994).

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Abstract: The Variable Age of Decollement Surfaces in the Gulf Coast of Texas and Louisiana

Robert O. Brooks

Over the past five years, improvements in 2-D and 3-D seismic resolution and the availability of new well data in the Gulf of Mexico have led to changes in previous interpretational concepts. The enhancement of deeper seismic in some areas shows evidence for regional decollements, which divide the Tertiary-Quaternary sediments into two separate structural realms. Where horizontal salt bodies exist, these decollements correlate to the base, and there is evidence for both extensional and compressional faults. In the absence of salt, decollements occur in ductile shales.

The age of the surfaces varies from Pleistocene downdip (Sigsbee Scarp) to late Eocene onshore and is seismically defined by a variety of common visual seismic signatures that can be integrated with limited well control.

For many years, interpretational concepts along the Gulf Coast and out across the Gulf of Mexico shelf were dominated by shifting depocenters,

large extensional listric growth faults, and vertically injected piercement domes rooted in the Jurassic Loanne salt. Re-evaluation of salt injection features based on 180,000 miles of 2-D regional seismic data and integration of 10-12 key wells has focused greater emphasis on the relationships between salt and decollement surfaces, horizontal salt injection and weld zones.

The recently announced discoveries in Ship Shoal 349 and Mississippi Canyon 211 are strong indications of a new deep exploration play in portions of the Gulf of Mexico.

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