REVISED MERAMECIAN (LOWER VISEAN) STRATIGRAPHY OF THE TRI-STATE DISTRICT OF OKLAHOMA, MISSOURI, AND KANSAS

A revised stratigraphic framework for the Meramecian of the Tri-State District of Oklahoma, Missouri, and Kansas has been constructed based on the integration of outcrop lithostratigraphy and conodont biostratigraphy. The proposed lithostratigraphic nomenclature for the Meramecian is, in ascending order, the Ritchey Formation (formerly Baxter Springs Member), Moccasin Bend Formation (formerly Moccasin Bend Member), and the Quapaw Limestone. As a whole the Meramecian of the Tri-State District is bounded above and below by regionally significant unconformities and includes at least one other unconformity separating lower and upper Meramecian strata.

The Ritchey Formation unconformably overlies the Short Creek Oolite Member of the Bentonville Formation (Osagean). In turn the Ritchey Formation is unconformably overlain by the Moccasin Bend Formation. Both of these unconformities are previously unrecognized and are regionally significant. Previous workers considered both of these units to be lower Meramecian, equivalent to the Warsaw Formation of the Upper Mississippi Valley. Conodont recoveries have confirmed this for the Ritchey Formation. However, based on our collections the Moccasin Bend Formation is upper Meramecian, equivalent to the lower St. Louis Limestone.

The Quapaw Limestone has been somewhat of an enigma. Previously it has only been recognized in outcrop at its type location and may have often been interpreted as part of the overlying Hindsville Limestone (Chesterian). While the original type location is poorly exposed the Quapaw Limestone is very well exposed in a nearby active quarry where both the lower and upper boundaries can be examined. Our initial interpretation is that the Quapaw Limestone is conformable with the underlying Moccasin Bend Formation and unconformable with Hindsville Limestone above. Moreover initial conodont recoveries suggest that Quapaw Limestone is upper Meramecian, equivalent to the St. Louis Limestone.