27 Recent Advances in Western Blue Ridge Geology

Friday, 24 March 2006
8:00 AM - 12:00 PM

CONODONTS FROM THE WALDEN CREEK GROUP, SOUTHEASTERN TENNESSEE

Paper number: 27-4
Program: THEME SESSIONS
Time: 8:45 AM – 9:05 AM

Authors

Abstract

Conodonts have been recovered from limestones in the Walden Creek Group in the western Blue Ridge foothills, southeastern Tennessee. The limestones sampled are mappable units within sub-chlorite grade shale and siltstone previously considered part of the Sandsuck Formation. The age of the Walden Creek Group in this region has been controversial since 1990, when R. and S. Unrug (Geology, 18:1041-1045) presented evidence of mid-Paleozoic fossils in these same rocks, assigned by them to the Wilhite Formation. Previously, these strata were interpreted to be of Late Proterozoic age. One locality, at Springtown, TN (= locality 12 of Unrug et al., 2000, GSA Bulletin, 112:982-996), is in a fault block bounded to the W by the Maggies Mill fault and to the E by the Miller Cove fault. The other is along Bivens Branch, a tributary of Citico Creek (= locality 7 of Unrug et al., 2000), in sub-chlorite grade mappable limestone interlayered with conglomerate and shale, also previously mapped as Sandsuck Formation. The locality is in a fault block bounded to the W by an unnamed fault, and to the E by the Miller Cove fault.

The conodonts found thus far are not notably deformed but are poorly preserved. They are almost all fragmentary and have moderate to thick mineral overgrowths, making them extremely difficult to recognize and identify. A probable element of Pseudooneotodus sp. (the genus range is Upper Ordovician into the Devonian) is the only specimen that can be identified even to genus thus far. Most of the specimens appear to be angulate and ramiform elements typical of ozarkodinid taxa.

Even though firm dates are not yet possible from the conodonts at hand, their morphotypes are indicative of and consistent with the age range of most of the fossils reported previously. The emplacement of a thrust sheet of younger rocks into the Blue Ridge thrust complex requires complete rethinking of the kinematics of assembly of this thrust complex.