HIGH RESOLUTION STRATIGRAPHY OF LOWER MISSISSIPPIAN STRATA FROM OUTCROPS IN NORTH CENTRAL ARKANSAS

Lower Mississippian strata in Northern Aransas include in ascending order the Bachelor Formation, Compton Formation, Northview Formation (Kinderhookian Stage), Pierson Formation, and overlying Reed Springs Formation (Osagean Stage). The Compton, Northview, and Pierson Formations are placed within the St. Joe Group. The Bachelor Formation unconformably overlies older Devonian rocks. The St. Joe Group was deposited on a depositional ramp and is exposed throughout outcrops across northern Arkansas. Outcrops for this study include Omaha East (reference locality in Boone County), Omaha West, Sellers Creek, Harriet East, AR-74, Walls Ferry North, Walls Ferry South, and Glenn Creek. These outcrops span across Boone, Searcy, and Independence counties.

Several hypotheses have been developed in order to explain the thinning of the St. Joe Group in Northern Arkansas. One of these being that the St. Joe group thins into a basinal condensed section (Thompson and fellows, 1970). If this were true it would be expected to find more mud supported carbonates reflecting a more shelf depositional environment, rather than grain supported. The other is proposed that the St. Joe Group is thinning over a structural fore-bulge (Mazzullo et al. 2011). Bed by bed analysis with detailed petrographic and faunal analysis of the St. Joe Group from various localities provides evidence to support one of these hypotheses.