SUBSURFACE TO OUTCROP: MISSISSIPPIAN CONODONT BIOSTRATIGRAPHY OF THE MIDCONTINENT US

With ongoing oil and gas exploration in the Mississippian strata of the Midcontinent United States geologists are looking into the lateral and vertical trends in reservoir continuity within the subsurface. The study proposed herein will quantify The Boone Group (Upper Osagean) formations of the Mississippian with a detailed high frequency biostratigraphic framework. A recently proposed model for the Osagean strata proposes that a change in depositional style of the Bentonville Fm is noted above the basal dolomitic part of the Pierson Fm (Polygnathus communis carina Zone and lowermost Pseudopolygnathus multistriatus Zone) in which sedimentation on the Burlington shelf to shelf-edge to shallow basin undergoes a time transgressive change. This change in depositional nature of the Boone Group is thought to be a result of local tectonic and sedimentary responses associated with fault-controlled diachronous subsidence of the Burlington Shelf into the shallow basin. Mississippian tectonics can be resolved by high resolution conodont biostratigraphy through the use of conodont zonation within formations. This study consists of a bed by bed analysis of the Reeds Spring Fm and the Bentonville Fm (formerly known as the Burlington-Keokuk Fm.) which outcrops along US highway 65 in northern Arkansas (Boone County, Arkansas). The Lower “texanus” Zone and the Middle “texanus” – pseudosemiglaber Zone of the upper Osagean (Visean Stage) will be evaluated in order to develop a high resolution sedimentological and paleoecological model for the Boone Group of the Midcontinent. With outcrop data analyzed, subsurface biostratigraphy is also developed on three cored sections of the Mississippian in Payne and Logan county Oklahoma; East of the Nemaha Ridge. Relating the biostratigraphy in the subsurface to outcrop observations leads to a regional biostratigraphic framework for the Mississippian Limestone.