Salt-Sediment Interaction and Passive Diapirism: A Field-Based Story of La Popa Salt Diapir Rise Coeval with Deposition of Viento Formation, La Popa Basin, NE Mexico
The Paleocene/Eocene Viento Formation is the youngest shallow marine unit preserved within the La Popa minibasin of northeastern Mexico. Facies distribution and stacking pattern of Viento Formation siliciclastic strata exposed adjacent to the partially-welded La Popa evaporite diapir are analogs for subsurface hydrocarbon—bearing reservoirs adjacent to salt structures in the Gulf of Mexico. The Viento Formation within the La Popa minibasin was influenced by syn-depositional rise of La Popa salt diapir, eustatic sea level changes and Hidalgoan shortening across the region, which controlled depositional facies distribution, stratigraphic architecture, and structural geometry of diaper-flanking strata.
Viento Formation strata are exposed along a ~5 km belt adjacent to La Popa salt diapir, which consists of discontinuously outcropping remnant gypsum. The Viento Formation displays thinning to pinch-out over ~900 m distance and forms a series of five stacked sequence stratigraphic wedges ranging from 25 to 200 m thick. Beds dip vertically at the weld, but dip orientations decrease to ~30° basinward. Sharp, subaqueous erosional surfaces and abundant, low-angle unconformities that becomes conformable within tens of meters distance from the diapir, characterize wedge halokinetic sequence boundaries.
Overall sand-prone lithofacies successions are shallowing upward and indicate deposition in a tide-influenced delta system. Interesting, conglomerate and conglomeratic sandstone contain abundant diapir-derived detritus; Jurassic metaigneous boulders that decrease in abundance, size, and angularity in a basinward direction. These suggests that cyclical tectonic compressional events coeval, combined with continuous sediment loading, controlled the La Popa salt diapir rise and drove episodic diapir extrusion. Viento stratal composition, distribution, and distinct geometry of halokinetic drape folding forms a tapered composite halo-kinetic sequence that reflects an overall increase in local third-order net sediment accumulation rates relative to salt rise rates.
AAPG Datapages/Search and Discovery Article #90219 © 2015 GCAGS, Houston, Texas, September 20-22, 2015