Abstract

Here we outline the current status of a renewed effort to integrate geophysical data with petrologic and geochemical data from the Precambrian basement of the Permian Basin in order to more fully understand basement evolution. Integration of gravity, seismic, and well data shows that the Central Basin Platform, and adjacent parts of the Midland and Delaware Basins are underlain by layered mafic rocks, the Pecos mafic intrusive suite. The suite takes the form of a 3-10 km thick sill with a dike-like keel that may represent the core of a ~1100 Ma rift. This rifting event may be associated either with extension in the foreland of the Grenville orogeny or with hot-spot-related extension that formed the Midcontinent rift. If this interpretation is correct, petroleum exploration targets in the form of erosional remnants of rift sediments may still lie within basement. Gravity modeling shows that the largest geophysical feature in the Permian Basin region, the Abilene Gravity Minimum, is associated with a 10 - 20 km thick low density body within basement. Although the origin of this feature is still enigmatic, it has most commonly been interpreted as the location of the Grenville front in Texas. More recently it has been suggested that the Abilene Gravity Minimum is caused by a batholith-scale intrusive complex related to a ~1350 Ma continental arc. Additional geochemical and geochronologic studies of basement rocks from the Abilene Gravity Minimum are required to fully understand the tectonic significance of this feature.