Outcrop-to-Subsurface Stratigraphic Correlations of the Upper Desmoinesian and Lower Missourian Stages (Pennsylvanian) in Eastern Kansas

Pennsylvanian (Upper Carboniferous) strata in eastern Kansas have been investigated for more than 120 years. We have determined, however, that discrepancies arising from emphases on either outcrop observations or subsurface data, as well as the loss of some key outcrops since their first descriptions, created major problems in prior stratigraphic interpretations. One particularly problematic stratigraphic interval contains the boundaries between units in the Marmaton (Desmoinesian) and Pleasanton (Missourian) groups, which encompasses the global Moscovian-Kasimovian stage boundary. We use 246 petrophysical well logs, especially gamma ray and neutron logs, to provide greater stratigraphic control among 22 previously described type outcrops, neostratotypes, and principal reference localities. Nine new stratigraphic cross sections resulting from our analysis of these data permit innovative interpretations of ancient facies belts as well as a reassessment of the geometry and structural history of the Cherokee–Forest City Basin. We make three recommendations regarding group boundaries on the basis of our analysis: 1) The boundary between the Cherokee and Marmaton groups should be placed at the base of the Excello Shale, thereby including the unit within the Marmaton Group. An unnamed limestone underlying the Excello Shale and observed in some areas should ideally be included within the Marmaton, but this unit will require further study. 2) The boundary between the Marmaton and Pleasanton groups should be placed at the base of the Nuyaka Creek Shale Member, as opposed to the standing placement at the base of the Hepler Sandstone. 3) The boundary between the Pleasanton and Kansas City groups should be maintained at the base of the Critzer Limestone Member of the Hertha Limestone. Additionally, we advocate the following changes to stratigraphic nomenclature in Kansas: 1) the Fort Scott Limestone should be revised to include the Excello Shale; 2) members of the Lenapah Limestone (the Idenbro Limestone Member, Perry Farm Shale Member, and Norfleet Limestone Member) should be abandoned because of prior miscorrelations; 3) the stratigraphic interval between the Lenapah Limestone and the Nuyaka Creek Shale Member correlates to either the Holdenville Shale or Memorial Shale—therefore, we leave this interval unnamed; and 4) with our proposal to place the lower boundary of the Pleasanton Group at the base of the Nuyaka Creek Shale Member, the lower boundary of the Lost Branch Formation should likewise be moved to that same level. The stratigraphic contexts of the Seminole, Tacket, and Shale Hill formations remain to be clarified by future work.