AGE CONSTRAINTS ON THE FORMATION OF THE DEVONIAN FLYNN CREEK STRUCTURE, TENNESSEE
The post-impact fill of the crater consists of black shales that were long thought to be equivalent to the Late Devonian Chattanooga Shale. Only the upper third of the black shale succession, however, is correlative to the Chattanooga Shale. Most of the black shales in the crater are older, and are separated from the overlying Chattanooga Shale by an erosional truncation. The upper portion of this lower black shale package contains conodonts that imply deposition during upper MN 5 to 6. The basal shale package of the overlying Chattanooga Shale (separated by erosional truncation) contains conodonts that indicate deposition during MN 6 to 7.
Based on condont ages and sedimentological constraints it appears therefore that the Flynn Creek impact post-dates the Amönau Event (base of MN Zone 1), and pre-dates the Alamo Impact (MN Zone 5). Thus, within the limitations of biostratigraphic age determination available for the Late Devonian, the Flynn Creek impact can not be linked to other known Devonian impact events.