Subsurface Study of Atoka (Lower Pennsylvanian) Clastic Rocks in Parts of Jack, Palo Pinto, Parker, and Wise Counties, North-Central Texas

Abstract

A lithofacies analysis of the subsurface Atoka clastic rocks in parts of Jack, Palo Pinto, Parker, and Wise Counties, north-central Texas, was designed to provide a meaningful interpretation of depositional environments that existed during Atokan time, as well as the most favorable areas for production of hydrocarbons. The Atoka clastic rocks are the product of the Ouachita orogene interacting with an epeiric sea on the west during Early Pennsylvanian time. They are a series of sediments deposited between the Caddo Limestone of Strawn age and the top of Marble Falls Limestone of Morrowan age. The study area is in the west-central part of the Fort Worth basin which is a pericratonic or retro-arc basin in plate tectonic terminology. The deepest part of the basin is adjacent to the folded and thrust-faulted Ouachita belt on the southeast. The subsidence of the Fort Worth basin during Atokan time accommodated the eroded detritus from the rising Ouachita system on the southeast. Limestones were accumulating in the western area where more stable conditions existed on the Concho platform. The investigation provided valuable information that may augment hydrocarbon exploration programs throughout the basin; the procedure of investigation can be applied to similar basins beyond the confines of the immediate area.