--> Abstract: Proposed Vast Hydrocarbon Play Along The Gulf Of Cadiz Continental Margin, by L. Somoza, A. Maestro, and A. Lowrie; #90928 (1999).

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SOMOZA, LUIS1, MAESTRO, ADOLFO1, and LOWRIE, ALLEN2
1Geological Survey of Spain, Madrid, Spain
2Consultant, Picayune, Mississippi, USA.

Abstract: Proposed Vast Hydrocarbon Play Along the Gulf of Cadiz Continental Margin

Extensional tectonics triggering salt withdrawal and large mass-wasting along the oceanic entrant to the Gulf of Cadiz, Iberian and Moroccan continental margin, may be the trapping mechanism for hydrocarbons buried beneath large allochthonous. The area of burial could be as high as 90,000 km2 with potential reserves rivalling those of the Gulf of Mexico subsalt play. Hydrocarbons may be trapped beneath and/or incorporated into the allochthons themselves. These migrating allochthons apparently may have travelled up to 400 km downslope, originating along the Iberian and Moroccan continental margins. The complex geologic evolution may have begun on the Betic passive margin where allochthonous evaporites were emplaced during the Late Cretaceous-Palogene and later, during Neogene times, over-thrusted by the Alboran platelet, forming an accretionary wedge onto the Gulf of Cadiz. The westward Gibraltar arc migration oversteepened the Atlantic-facing Iberian-Moroccan continental margins. This movement initiated further westward migration of gravity-driven continental and salt-floored blocks whose ultimate emplacement was over oceanic crust. As the continental blocks migrated, normal listric faulting along the present continental shelf of the Gulf of Cadiz, as the continental blocks developed, providing continental shelf accommodations for upper-Miocene (past 19 Ma) tectonics and deposition. Multiple stacking of thrusting wedges, possibly migrating over Triassic salts and/or overpressured Miocene marls, apparently occurred at the foot of the allochthonous blocks with mass-wasting further downslope. Interaction along lateral migration can generate compression zones that, in turn, can provide extensive fracturing, faulting, and jointing, suitable for further petroleum storage. This is the first proposed ocean basin hydrocarbon province based on long-distance allochthon/mass-wasting migration.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas