Gamma Ray Analysis of a Carbonate Mud-Mound on Center Hill Lake

Abstract

The purpose of this project is to use wireline logs to determine the presence or absence of Maury Shale and carbonate mud mounds at the base of the Fort Payne Formation (Mississippian) in central Tennessee. For this project, we chose a mud mound in a well-exposed carbonate system on Center Hill Lake, latitude 35.85N and longitude 85.64W. The method employed to acquire data was a hand-held gamma ray scintillometer, an instrument that determines the percentages of potassium, uranium, thorium, and total dose rate of gamma rays. Initial fieldwork was completed during the summer of 2018, and scintillometer results from five measurements showed low values for each element and total dose rate. These results suggest that the outcrop lacks significant shale deposits. The general stratigraphy for the mud mound was an upper slab section and lower “chippy” section. Typical facies of this outcrop include crinoidal packstone and grainstone, massive fenestrate bryozoan coral, crinoidal wackestone and gray-green fossiliferous shale. Future work will focus on additional measurements across the mound to characterize lateral and vertical compositional trends.