Sequence stratigraphy and lithostratigraphy of Devonian reservoir successions, Arkoma Basin, northeastern Oklahoma and northern Arkansas

The Devonian System is represented in the northern Arkoma Basin of Arkansas and immediately adjacent Oklahoma by three unconfornity-bounded units designated the Penters Interval, Clifty Formation and Chattanooga Shale, in ascending order. In Arkansas, these units are assigned Lower, Middle and Upper Devonian/Lower Mississippian ages respectively, although biostratigraphic data are uneven. Subsurface analysis of the units indicates that the Penters interval is a pervasive deposit of penecontemporaneous chert and calcisiltites. The Penters can be separated into "Upper" and "Lower" intervals that are divided by a Lower Devonian Shale Marker, which reflects a transgression, maximum flooding and highstand across a siliciclastic, carbonate-rimmed shelf. Chert lithology mirrors that of the lower Boone Formation (Lower Mississippian) suggesting a volcanic source of the silica and deposition below the sediment-water interface, while the calcisiltites were still poorly indurated. The Middle Devonian was a period of mostly erosion that is represented in Arkansas only by the Clifty Formation, a lowstand shoreface deposit. The succeeding transgression during the Upper Devonian is represented by the Sylamore Sandstone, basal member of the Chattanooga Shale. It is a chertarenite with a significant fraction of angular, phosphatic, and chert gravel as well as a small orthoquartizic sand component. The Chattanooga is a dark, black, carbonaceous shale that has pronounced thickening south and east of its outcrop, and a basal contact forming an angular unconformity with earlier strata.