Sequence Stratigraphy of Mississippian Oolitic Limestones in Northern Arkansas

C. Robertson Handford

Mississippian carbonate rocks in northern Arkansas make up two major depositional sequences belonging to a ramp that evolved along the southern margin of the North American craton during Paleozoic time. A Lower Mississippian unconformity-bound sequence is made up of the St. Joe Limestone and the overlying Boone Formation. The Upper Mississippian depositional sequence is made up of the Batesville-Hindsville formations and/or the Moorefield shale at its base, followed above by the Fayetteville Shale and Pitkin Limestone. A regional unconformity separates the Upper Mississippian sequence from the overlying Pennsylvanian clastics.

St. Joe Limestone makes up the transgressive systems tract and the overlying Boone Formation was deposited as a highstand systems tract in the Lower Mississippian depositional sequence. Oolitic limestones are uncommon in this sequence and only occur near the top of the highstand Boone Formation as the Short Creek Oolite Member. The St. Joe thins over a short distance basinward in northern Arkansas into a highly condensed or starved section, but the highstand Boone deposits extend farther basinward and represent a ramp that prograded into water depths of approximately 400 ft.

The Upper Mississippian depositional sequence includes abundant, cross-bedded oolitic limestones in both the transgressive Hindsville formation and the high-stand Pitkin Limestone. Black, cephalopod-bearing Fayetteville Shale lies between these two units and records transgressive deep-shelf environments. Highstand conditions began during deposition of the middle to upper Fayetteville with its interbedded shales and shelf storm-deposited limestones, and concluded with the deposition of cross-bedded oolitic Pitkin limestones in shallow shelf and shoreface environments.

AAPG Search and Discovery Article #91023©1989 AAPG Eastern Section, Sept. 10-13, 1989, Bloomington, Indiana.