Mark G. Rowan¹, Timothy F. Lawton², Katherine A. Giles²
(1) Rowan Structural Consulting, Boulder, CO
(2) New Mexico State University, Las Cruces, NM

Abstract: El Papalote diapir, La Popa Basin, Mexico: an exposed analog for northern Gulf of Mexico salt-flank and subsalt structures

El Papalote diapir is an exposed salt stock located in La Popa Basin, northwest of Monterrey, Mexico. It is elliptical in plan view (approximately 1x2 km) and is surrounded by Maastrichtian to Eocene rocks deformed during both diapirism and minor regional shortening. These strata include marine to nonmarine siliciclastics that thin toward the diapir, as well as locally developed carbonate 'lentils' that rimmed and covered the bathymetric high created by the growing passive diapir.

The edge of El Papalote is approximately vertical on three sides, where it is flanked by vertical strata that gradually thicken and return to regional dip within 800 m of the diapir. However, the diapir flares laterally on the southeastern, basinward flank, with the edge dipping 40° inward toward the diapir stem. Adjacent stratal geometries are highly complex, with repeated packages of lentils and associated siliciclastic wedges that are folded through vertical to completely overturned before being truncated by presently vertical unconformities.

We employ structural restoration to determine the evolution of the diapir. First, we remove the effects of regional shortening, in which the diapir served as a nucleation point for a minor, local flexure on a larger fold limb. Second, we illustrate the interaction between deformation and sedimentation during the passive growth of El Papalote diapir, which was characterized by repeated cycles of regional subsidence and deposition, diapir inflation and subsequent erosion, and salt extrusion and associated stratal deformation.

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