STRATIGRAPHIC ARCHITECTURE AND DEPOSITIONAL FRAMEWORK OF MISSISSIPPIAN (KINDERHOOKIAN TO OSAGEAN) EXPOSURES IN SW MISSOURI, NW ARKANSAS, AND NE OKLAHOMA

Exposures of Kinderhookian to Osagean rocks in Missouri, Arkansas and Oklahoma provide an opportunity to examine eustatic and tectonically-modified lithofacies and stratigraphic architecture along paleo-dip. The Kinderhookian Bachelor, Compton and Northview formations are an unconformity-bounded, TST-HST cycle of shallow-marine shales and limestones deposited along a ramp; micritic mounds in the Compton are present in a medial-ramp setting. The lower part of the Osagean Pierson Formation is a progradational cycle of nearshore dolomite to offshore crinoidal limestones that similarly was deposited on a shallow-water ramp. Crinoid-dominated mounds in this unit also are present in a medial-ramp setting seaward of the Compton mounds. The ramp deposits of these two cycles maintain their shallow-water identity down paleo-dip to where they thin and ultimately pinch out against an inferred topographic high of syndepositional tectonic origin. The overlying Osagean upper Pierson and cherty Reeds Spring formations record a cycle of rapid transgression followed by long-term progradation of low-energy limestones on a moderate-depth ramp; and these facies pass up-dip into shallow-marine, crinoidal sands in the lower Burlington-Keokuk. This cycle is truncated by a regional subaerial unconformity, below which a thick section of tripolite developed. The final TST-HST cycle comprises progradational, shallow-marine crinoidal sands in the upper Osagean Burlington-Keokuk Formation, which is capped by the Short Creek Oolite and which locally includes bryozoan reefs. The top of the Osage is a regional subaerial unconformity. Progradation of these Mississippian deposits was to the southwest and south, and disparate ages of individual progradational wedges are readily identified by conodonts.

Syndepositional tectonism related to the early stages of plate collision from the south are inferred in the Compton, Northview and lower Pierson by the presence of numerous intra-formational unconformities of likely subaqueous origin and only local extent, anomalous thinning or thickening, and northward progradation of HST deposits. Such tectonism also is inferred in the upper Pierson and Reeds Spring by rapid shallowing and/or thickening.