Abstract

Previous studies of the middle Comanche Series of south Texas have defined different stratigraphic units in each of four paleodepositional settings, which has impeded regional correlation and synthesis. The Edwards Group occurs across two distinct shelf areas, the San Marcos Platform and the Central Texas Platform. The Devil's River Formation encompasses a formally undivided shelf margin with common reef development, generally referred to the Devil's River Trend. The Devil's River Trend separates the shelf platforms from the epicontinental Maverick Basin. The middle Comanche Series comprises two high-frequency sequences that provide for regional correlation. Each high-frequency sequence is divided into transgressive and highstand systems tracts, with the lowstand systems usually absent from the area of study. The lower high-frequency sequence includes the Kainer Formation (San Marcos Platform), the Fort Terrett Formation (Central Texas Platform), the lower Devil's River Formation, and the West Nueces and lower McKnight formations (Maverick Basin). The upper high-frequency sequence includes the Person Formation (San Marcos Platform), the Segovia Formation (Central Texas Platform), the upper Devil's River Formation, and the middle and upper McKnight and Salmon Peak formations (Maverick Basin).