Bradley M. Battista¹, Allen Lowrie², V. Makarov³, S.J. Moffett², L. Somoza⁴
(1) University of Southern Mississippi, Bay St. Louis, MO
(2) Consultant, Picayune, MS
(3) VNII geofizika, Moscow, Russia
(4) ITGE Geological Survey of Spain, Madrid, Spain

Abstract: Lateral tectonics in the Gulf of Mexico, Gulf of Cadiz, and the Middle America Trench: Impacts on hydrocarbon accumulations

Along the Louisiana offshore in the Gulf of Mexico, the lateral motion of the upper Jurassic, Callovian-age salt has created hydrocarbon reservoirs, due to sedimentation anomalies and tectonics. These reservoirs are created both above and below the migration salt. In north Louisiana, there is oblique faulting, indicated post-depositional tectonics within the passive margin. Similarly, westward migration of the Atlantic-facing Iberian-Moroccan continental margin has produced a series of thrust blocks or slivers extending beneath and west of the Gulf of Cadiz. These thrusts have initiated extensive mass wasting from rotational block faulting, to slump blocks, to debris flows and turbidites extending some 500-600 km into the Atlantic Basin. Drilled salt layers beneath and above the thrusts may serve as lubrication layers and as generators of hydrocarbon traps. Note that both of these margins contain extensive Cretaceous “black shales” a prominent source of organics. The Gulf of Mexico has begun a sub-salt hydrocarbon play; the Gulf of Cadiz may be the next such play. Analysis of fine-order processes reveals thrusts or slivers accumulated along the active continental margin. Descending sediments from the adjacent continent are deposited above the protruding thrusts. Zones of low velocity are suggestive of under-compaction and/or gas accumulations. In all three margins described, common themes are the existence of thrusts/slivers, and common lubricating materials. The similarity of large-scale tectonics between so-called passive and active margins requires commonality of processes, the study of which in each area may improve total understanding.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana