Controls on Cretaceous and Paleogene Reefal Carbonate Platforms Developed on Passive Salt Diapirs, La Popa Basin, Northeast Mexico

Katherine A. Giles and Dominic Druke
Institute of Tectonic Studies, New Mexico State University, Las Cruces, NM

Comparison of facies types, distribution, and stacking patterns of carbonate platforms that periodically developed on 3 isolated salt diapirs in La Popa basin is used to interpret the complex interplay of halokinesis, paleogeography, local nutrient flux, eustasy, and regional tectonics in controlling depositional patterns.

La Popa basin contains a thick (>6km) succession of shelfal marine siliciclastics that shallow upward to fluvial redbeds. Carbonate units (<350m thick) within this succession are spatially confined to salt diapirs and are temporally confined to periods of major marine transgression. Carbonates preferentially utilized diapir topographic relief, which provided a shallow water depositional surface protected from siliciclastic influx and was the site of elevated nutrient levels charged by methane seeps. Diapir relief and methane seepage were greatest during periods of marine transgression and were suppressed by increased siliciclastic onlap/overlap during marine regression. Carbonate facies distribution is asymmetrical on the roughly circular 4km2 diapirs, reflecting windward versus leeward margin affects. Windward (SW) margins are dominated by steep-sided sponge, coral, red algal reefs displaying minor forereef progradation (<.5km). In contrast, leeward (NE) margins are dominated by foram, red algal grainstone banks displaying major progradation (2-6km).

Hidalgoan shortening of La Popa basin formed large wavelength folds. Diapirs that lie in the hinges of folds were “squeezed” significantly more than diapirs on the limbs of folds. Squeezed diapirs generated much higher and broader bathymetric relief and are dominated by shallow water sponge-coral-red algal reefs with carbonate strata that extend as much as 6 km away from the diapir. Age equivalent strata on limb diapirs contain deeper water oyster-red algal packstone facies that extend < 2km from the diapir.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005