Latest Wolfcampian Tectonism as a Control on Early Leonardian Carbonate Slope Channel Complexes

Ted E. Playton
The University of Texas at Austin, Austin, TX

Outcrops in the Victorio Flexure area of the Sierra Diablo Mountains, West Texas, provide evidence that suggest 1.) Ouachita-related tectonism remained active throughout early Permian time in the Delaware Basin, and 2.) margin-to-slope topography generated from these tectonic events can focus sediment downslope resulting in channelized carbonate debris accumulations. In the Late Wolfcampian, a distally-steepened carbonate ramp (Hueco ‘C' Formation) developed in proximity to the Victorio Flexure monocline along the western margin of the Delaware Basin. In latest Wolfcampian time, significant rotation of the Victorio Flexure monocline increased slope height by over 170 m and slope gradient by more than 60. Pre-existing ramp sediments were slump deformed, and significant reentrant topography formed along the upthrown hinge of the monocline. These reentrants and slump topography acted as downslope funneling mechanisms for early Leonardian (lower Abo Formation) carbonate debris. This debris bypassed the upper slope and deposited at the lower slope and basin positions in the form of amalgamated channel complexes that display proximal-to-distal and axial-to-flank relationships.

Knowledge of Late Wolfcampian tectonic activity provides additional information to constrain the waning of Ouachita-related tectonism in the Delaware Basin, and perhaps throughout the Permian Basin system. Shelf margin and upper slope topography as sediment focusing controls are critical components for carbonate slope channelization, and enhance the efficiency of sediment delivery into the basin. Basinal, grainy carbonate accumulations can survive diagenetic deterioration of reservoir quality, and channelization linked to previous topography may help to explain their distribution.