APPLICATION OF MISSISSIPPIAN (KINDERHOOKIAN TO OSAGEAN) OUTCROP MODELS TO SUBSURFACE PETROLEUM SYSTEMS IN SOUTHERN KANSAS AND NORTHERN OKLAHOMA: BRIDGING THE GAP

Understanding Mississippian petroleum systems in the mid-continent has been largely problematic, mainly because of the complexity of stratigraphic units along the paleoshelf- break transition, confusion in lithostratigraphic terminology, and the overall lack of depositional systems models. Mississippian exposures in SW Missouri, NE Oklahoma and NW Arkansas offer a 3-D model of lithostratigraphy and depositional systems that is the framework for understanding Kinderhookian and Osagean rocks in the subsurface. Seismic profiles and subsurface correlations reflect geometries and depositional system relationships that are present in outcrops. Existing cores, and cores taken for stratigraphic resolution, illustrate that lithostratigraphic units that are present in surface exposures also are present in subsurface Kansas and Oklahoma. The Kinderhookian Bachelor, Compton and Northview formations, for example, share similar lithologies to those on outcrop, and these units were deposited on a shallow ramp with a similar history of TST-HST cycles truncated by unconformities. In contrast to the outcrop, the switch in depositional motif from shallow-water ramps to a more steepened, progradational ramp in the subsurface began with deposition of the lower Osagean Pierson Fm. and continued during subsequent Osagean time. This switch is represented by a facies change from shallow water to more offshore deposits that are recorded seismically. Overlying the Pierson is the Reeds Spring Fm., which grades rapidly upward to porous tripolite representing a TST-HST that is truncated by a major unconformity. The Cowley Fm. was deposited on this unconformity in the subsurface as a lowstand wedge that is not present on outcrop. Regionally, the Burlington-Keokuk (upper Osagean) overlies the Reeds Spring and Cowley as the next major TST-HST cycle.