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Abstract: Late Paleozoic Tectonic Evolution of the Eastern Margin of the Diablo Platform, West Texas

D. B. Swift, K. T. Barrow, A. Schoellkopf, J. J. Reeves, R. J. Erdlac

The Diablo platform is a long-lived positive tectonic feature that forms the western and southwestern margin of the Delaware basin of west Texas and New Mexico. The platform is known to have been episodically active from at least the early Paleozoic to the Holocene. Although the western margin of the platform is well exposed in fault blocks formed during Tertiary Basin-and-Range-style deformation, the eastern margin is largely concealed beneath Cretaceous to Holocene sediments and Tertiary volcanics. Well control along the eastern margin of the Diablo platform is sparse, averaging less than one sub-Permian penetration per 128 km2 (50 mi2).

This study is part of a larger effort to utilize newly acquired seismic data, reprocessed older seismic data, and subsurface well control to formulate a structural interpretation of the Delaware basin and its margins. Early 1970s-age Delaware basin group-shoot seismic data were reprocessed to image parts of the eastern margin of the Diablo platform. Data were reprocessed with a high-performance interactive computer workstation and commercially available software. Improved seismic imaging is obtained by detailed velocity analysis and residual statics.

Results show that part of the eastern margin of the Diablo platform is bounded by west-dipping reverse faults having up to 1000 m (3300 ft) of vertical displacement. These features are Pennsylvanian and Early Permian in age and are analogous to compressional features on the eastern side of the Delaware basin bordering the Central Basin platform. High-angle normal (oblique?) faults having as much as 2000 m (6600 ft) of vertical displacement are, in part, younger than the reverse faults, cutting beds as young as Permian (Ochoan) age (Rustler Formation). These features are interpreted to reflect Pennsylvanian-aged northeast-southwest-oriented compression followed by Middle to Late Permian differential subsidence of the Delaware basin relative to the Diablo platform. Analogy with the basi -bounding margin adjacent to the Central Basin platform suggests that undiscovered compressional structures may exist along the eastern margin of the Diablo platform.

AAPG Search and Discovery Article #90980©1994 AAPG Southwest Section Meeting, Ruidoso, New Mexico, April 24-26, 1994