THE USE OF SEQUENCE STRATIGRAPHY TO PREDICT THE DISTRIBUTION OF CONODONTS IN THE FAYETTEVILLE SHALE, NORTHERN ARKANSAS

The Late Mississippian Fayetteville Shale is a dark siliciclastic unit that is exposed in northern Arkansas. The sequence stratigraphy of this unit is known. We used this published sequence stratigraphic model to more fully test the idea that it is possible to use sequence stratigraphy to predict where conodonts occur in significant abundance on shale surfaces in deeper water siliciclastic units. A total of 12 samples were collected 1.75 miles south of Marshall, AR from a northeast-facing road cut exposure of the Fayetteville Shale on US Highway 65. Two horizons that were previously described as flooding surfaces, and which we interpret to be a maximum flooding surface and a parasequence top flooding surface, were collected. The other samples were collected at random intervals throughout the formation. All samples were dark grey shale. The surface of all shale samples were examined under a binocular microscope for conodonts. Conodonts were common in the samples that were collected from flooding surfaces and absent in all other samples. We interpret the results of this study as support for the idea that sediment starvation occurred in intervals that represent flooding, and that higher sedimentation rates in the other samples diluted the conodont abundance. These results suggest that careful sequence stratigraphic analysis is a powerful tool in predicting where biostratigraphically significant microfossils concentrations occur within deeper water siliciclastic rocks.