*WINNER* Comparison of the Chattanooga Shale Formation Inside and Outside the Flynn Creek Crater, Jackson County, Tennessee

Abstract

The Flynn Creek crater is a 200 meter deep impact structure estimated to be formed in the Devonian period approximately 360 million years ago. The impact structure is 3.8 kilometers in diameter and is located 8 kilometers south of Gainesboro, in Jackson County, Tennessee (36°17’ N, -85°40’ W). When the impact occurred, the area was a shallow marine environment. The deposition of the Chattanooga Shale Formation was deposited after the impact occurred. The units effected by the impact were flat lithified Ordovician limestones and dolomites. The Chattanooga Shale near the Flynn Creek area is mainly black in color and can reach up to 55 meters in thickness. This research will test the hypothesis that the Chattanooga Shale formation inside the Flynn Creek crater may be older than the Chattanooga Shale formation outside of the crater. For this hypothesis, a hand-held Gamma Ray scintillometer was used to collect spectral data from the shale. Thirty-six measurements with the scintillometer will determine the amount of potassium (%), uranium (ppm), thorium (ppm), and overall gamma ray dose rate (nGy/h) for the two shale outcrops at Flynn Creek. Eighteen measurements were taken inside of the impact crater. The average gamma ray dose rate for this outcrop averages 172.13 nGy/h. Future field work will collect the remaining eighteen measurements outside of the Flynn Creek Crater. The average gamma ray dose rate of that outcrop will determine whether the two outcrops of Chattanooga Shale differ from one another in age.