CONTINUITY OF C. W. WILSON’S MIDDLE ORDOVICIAN STRATIGRAPHY FROM THE NASHVILLE DOME TO THE FOOTWALL OF WHITEOAK MOUNTAIN–CLINCHPORT THRUST: KEY TO UNDERSTANDING THE MIDDLE ORDOVICIAN (TRENTON–BLACK RIVER) PETROLEUM SYSTEM

The Middle Ordovician carbonate bank facies of C. W. Wilson (Nashville/Trenton and Stones River/Black River Groups) have been described in detail and mapped from the Nashville dome through the subsurface beneath the Cumberland Plateau, using well log geophysical signatures, to the western Valley and Ridge in TN, southern KY, and southwestern VA. The sequence above the Knox unconformity consists of the discontinuous Wells Creek (Blackford, Douglas Lake) Dolomite, massive Murfreesboro Limestone, thin-bedded Pierce Limestone, Massive Ridley Limestone, thin-bedded Lebanon Limestone, and massive Carters Limestone containing the Deicke and Millbrig bentonites near the top to comprise the Stones River Group. The silty/shaly Hermitage Formation, massive Bigby–Cannon Limestone, and shaly Catheys Formation comprise the Nashville Group. The Bigby–Cannon Limestone and the lower Stones River Group are known oil-producing intervals. These facies extend into the Valley and Ridge to the footwall of the Clinchport–Whiteoak Mountain thrust system from E of Chattanooga, TN into SW VA. To the E, the thin platform carbonate bank facies changes to a thickened, more bank-edge facies then to a very thick siliclastic basin facies. The thickening carbonate facies marks the approximate western edge of the Taconic back-bulge (Middle Ordovician) and foreland (Upper Ordovician) basins. Palinspastically restored cross sections locate the eastern edge of the Ordovician carbonate bank 50-75 km E of the Clinchport–Whiteoak Mountain fault, at approximately today’s TN-NC border. Recognition of the continuity in stratigraphy over this wide an area has both stratigraphic and tectonic implications, but also is important because the Stones River–Nashville Groups are known hydrocarbon producers and comprise a definable petroleum system. The region W of the Clinchport–Whiteoak Mountain fault system lies in the oil/gas window.