CONODONTS AND UPPER DEVONIAN STRATA ON THE NORTHWEST MARGIN OF THE NASHVILLE DOME, CHATTANOOGA AND NEW ALBANY SHALES

Two drill cores, one from Humphreys County, TN, which preserved 5 m of Frasnian strata and 10 m of Famennian strata; and one from Butler County, KY, which preserved 19 m of Frasnian strata, and at least 10 m of Famennian strata on the northwest margin of the Nashville Dome have similar conodont faunas, in part, and demonstrate preservation of depositional packages and condensed or erosional intervals in the pyritic black shale facies of the Chattanooga and New Albany shales. The Humphreys County core starts with the black shale developed on a lag bed over Givetian carbonates that contains Polygnathus ordinatus, Schmidtognathus wittekindti, and Zieglerina ovalis suggestive of FZ 3. This is overlain by an interval of FZ 4-6 characterized by Palmatolepis punctata, and then a condensed interval of FZ 8-13 to the Frasnian-Famennian boundary. A lag at the boundary contains Ancyrodella hamata, Ancyrognathus sinelamina, P. bogartensis, P. linguiformis, P. minuta minuta, P. regularis, P. triangularis, and P. winchelli - indicators of five to six zones that have been eroded and not preserved across the boundary. The base of the Famennian is represented by strata assigned to the prima Zone. In the Butler County core the black shale containing conodonts of the disparalis Zone overlies calcareous gray shales. The lowest Frasnian conodont, Ad. soluta indicates FZ 2-4. FZ 4-8 are indicated by P. punctata, P. transitans, and P. riemersi. FZ 9-11 are indicated by P. ljaschenkoae; and approximately 5 m of FZ 13 are indicated by P. hassi, P. winchelli, and P. extensa. The Frasnian-Famennian boundary is conformable, the base of the Famennian is indicated by the first occurrence of P. subperlobata and the triangularis, delicatula platys, and minuta minuta zones are also preserved.