Fault–fracture related “hydrothermal” carbonate reservoirs such as Albion–Scipio (Michigan) are prolific hydrocarbon reservoirs producing mainly from secondary porosity formed through hydrothermal leaching and brecciation by warm (~60°C–150°C) basinal brines. This paper, for the first time, shows that hydrothermal reservoirs may exist in the Mississippian age limestones (“Miss Lime”) of the southern midcontinent. The chapter is pivoted on the observation of a structural depression in a 3-D seismic volume from Payne County in north-central Oklahoma. The depression involves Pennsylvanian to Ordovician (and possibly deeper) units and is fully enclosed by normal faults. Overall, the fault-bounded depression appears to be a...