AN INDEPENDENT CONSTRAINT ON THE AGE OF THE GRAY FOSSIL SITE, TN USING COSMOGENIC NUCLIDE BURIAL DATING ON A 35-M-DEEP CORE
Cosmogenic nuclide burial dating provides an opportunity to independently estimate the age of the site and the local erosion rate. By measuring cosmogenic 26Al and 10Be at a range of depths and modeling their production and decay, it is possible to date deposits through the Pliocene. We measured 26Al and 10Be concentrations at eight intervals throughout the 35-meter-deep core previously described by Zobaa et al. (2011). The 10Be concentrations showed an exponential decrease with depth, reflecting the transition from neutron-dominated postburial production of cosmogenic nuclides at shallow depths to muon-dominated postburial production at greater depths. At the core’s base, 26Al and 10Be concentrations were 3.48 ± 0.60 ·104 at/g and 4.54 ± 0.29 ·104 at/g, respectively. These concentrations correspond to a minimum age of 4.51 ± 0.42 Ma, consistent with biostratigraphic age estimates. Additional 26Al measurements will provide a more precise estimate of the site’s age. We will present additional measurements and a refined age of the fossil site, as well as an overview of its implications for regional geologic history.