--> Abstract: Structural Development of the Perdido Fold Belt and the Alaminos Canyon Gravity Low: Deep Water Gulf of Mexico, by Bill Kilsdonk, Tim Grow, and Troy D. Waller; #90082 (2008)

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Structural Development of the Perdido Fold Belt and the Alaminos Canyon Gravity Low: Deep Water Gulf of Mexico

Bill Kilsdonk, Tim Grow, and Troy D. Waller
Hess Corporation, Houston, TX

In the Perdido fold belt of Alaminos Canyon, structural styles are largely controlled by the thickness of the deep salt which has flowed both to detach folds and to core anticlines. The frontal folds of the Perdido trend NE-SW and the fold belt ends to the SE where the salt pinches out. Frontal folds are developed over a thin salt layer which eventually thickens to the NW. Where the salt is thin, fold limbs are kinked - they may become faults at depth - and fold amplitudes are limited by the salt budget: folds stop growing when the salt beneath synclines thins to zero. Above thicker salt, fold shapes are more sinusoidal and fold crests are higher. Local gravity minima correlate with salt cored anticlines whereas synclines - with little or no underlying salt - correlate to gravity maxima. An erosional unconformity truncates the crests of anticlines and is continuous to the NW with the base of allochthonous salt which has moved down-slope to the SE. In the highest folds, the unconformity cuts the crests of anticlines down to their salt cores, exposing shortened and thickened bodies of salt. In places, a shallower allochthonous salt canopy has overridden eroded fold crests and sutured with the thickened “autochthonous” salt core, further increasing the total salt thickness.

Additionally, the allochthonous salt canopy seems to have depressed some of the underlying folds and forced salt from beneath them. We interpret the underlying cause of the Alaminos Canyon gravity low - a feature that trends roughly parallel to the frontal folds of the Perdido and extends over 250 km in length and 20 km in width - as a thickened, shortened, and deeply eroded salt core of the highest Perdido folds that is, in places, sutured to overlying allochthonous salt. It is the up-dip continuation of the Perdido foldbelt.

AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery