HUTCHINGS, WADE D., University of Texas at Austin, Department of Geological Sciences, Austin, TX

ABSTRACT: Sequence Stratigraphy of the Permian Delaware Mountain Group, Delaware Basin, West Texas

A high-resolution sequence stratigraphic framework was developed for the Delaware Mountain Group in a distal basin floor setting in the Delaware Basin of West Texas. Cyclicity in the Delaware Mountain Group is better-expressed in distal basin floor settings due to bypass and erosion in base of slope and proximal basin floor settings. Eight low-order cycles were identified based on integration of 25 closely spaced electric logs and a 36-mi² 3D seismic survey from the Geraldine Ford field area, and several regional electric log cross sections in the western and northern Delaware Basin.

Low-order cycles in the basin are analogous in scale and order to composite sequences defined on the shelf, and are bound by regionally correlative organic rich siltstones in the Brushy Canyon and lower Cherry Canyon Formations, and by organic rich siltstones and carbonate mudstones in the Bell Canyon and upper Cherry Canyon Formations. These bounding surfaces are inferred to represent composite maximum flooding of the shelf and sediment starvation in the basin. Upward thinning stacking patterns and upward decreases in sandstone proportion characterize these low-order cycles. Two higher orders of cyclicity are defined in each low-order cycle.

Strong relation between several low-order cycles in the basin and composite sequences on the shelf supports previous studies. However, additional cycles in the basin suggest either the presence of unrecognized significant boundaries on the shelf or other external factors that caused basinal channel and lobe complexes to shift landward and sediment starvation to dominate.

AAPG Search and Discovery Article #90909©2000 AAPG Foundation Grants-in-Aid