Depositional dynamics and stratigraphic correlation, basal Atoka Formation (Spiro-Foster members), middle Pennsylvanian, Arkoma Basin, eastern Oklahoma

The Spiro succession within the lower Atoka Formation comprises up to three distinct sandstone intervals, which have historically, but informally been called the Spiro sandstone. Commercial quantities of dry gas were first discovered within this succession in the 1950's and it has been an important exploration target ever since. Understanding the depositional environment of each of the sandstone intervals within the Spiro succession will improve the geologic understanding and improve the exploration potential of those intervals within the Arkoma Basin.;The Spiro sandstone, Foster "Channel" sands, and lower Spiro sandstone comprise the sandstone intervals within Spiro succession. These intervals represent the regression from a shallow, marine, near-shore environment to an estuarine zone followed by a transgression to a marine environment. The Type 1 Morrowan/Atokan chronostratigraphic boundary lies within this sequence. This boundary probably occurs at the base of the Foster "Channel" sands, as the Foster "Channel" sands display the most incision of the three intervals.