MISSISSIPPIAN TRANSGRESSION IN THE APPALACHIAN BASIN

The Upper Mississippian Little Valley Formation is a mixed siliciclastic-carbonate unit that records a marine transgression in the Appalachian Basin. It reflects the initial inundation of the Price-Maccrady delta complex by the St. Louis Sea and marks a transition from terrigenous to carbonate sedimentation.

Five stratigraphic sections, representing the sedimentary accumulations near the northern terminus of the Little Valley's basin, were sampled in Tazewell County, Virginia. Thin-sections were prepared and point-counted utilizing standard sedimentary techniques. Sedimentary microfacies were then assigned to each slide, allowing a depositional model to be developed. Environments of formation ranged from high intertidal and supratidal sabkha to open marine shelf.

Repetition of microfacies was encountered in some of the sections, indicating the transgression was not a single, linear event. Data suggest the overall rise in relative sea-level was a series of transgressive pulses, separated by minor regressive events. Other factors such as basin warping and delta channel avulsion may have also affected the complexity of the sedimentary sequence.