ASSESSMENT OF BIOGEOCHEMICAL POTENTIAL FOR PALEOCLIMATIC RECONSTRUCTION OF THE GRAY FOSSIL SITE

The Gray Fossil Site, located in East Tennessee, is an early Pliocene lacustrine deposit (~4.5-4.7 Ma) renowned for its diversity of well-preserved vertebrate fossils [1]. Initial efforts at stratigraphic reconstructions were completed soon after the site’s discovery, but revisiting the geology of the locality from the perspective of organic geochemistry provides a new lens for paleoclimatic reconstruction. This presentation reports on a pilot study that serves as a prelude to to high-resolution biogeochemical sampling. It focuses on examining the biomolecules & isotopic record in samples from a sediment core collected from three depths (0m, 16m, 30m) at the top, in the middle of, and at the bottom of the fossil site strata, as well as three different samples of fossil wood. These data will provide a framework for assessing climate variations, from the earliest records from the locality to the final vestiges of the lake environment prior to its complete infilling.

The results of this preliminary investigation will i. provide insight into the vegetation of Southern Appalachian forests in the transition between Miocene and Pliocene climates, ii. illustrate intra-site diagenetic alteration and variation in preservation, iii. assess the influence of C₄ plants across deposition, iv. constrain previously described open/closed forest cycling based on pollen records, [2] and v. provide context for future biogeochemical studies.

[1] Samuels JX, Bredehoeft KE, and Wallace SC. 2018. A new species of Gulo from the Early Pliocene Gray Fossil Site (Eastern United States); rethinking the evolution of wolverines. PeerJ, 6:e4648.

[2] Ochoa D, Whitelaw M, Liu YS, and Zavada M. 2012. Palynology from Neogene sediments at the Gray Fossil Site, Tennessee, USA: Floristic implications. Review of Palaeobotany and Palynology 184:36-48.