(U-Th)/He Zircon Thermochronology of the Cumberland Plateau, Tennessee: Insights into the Thermal History of the Southern Appalachian Basin

Session: 37th Annual Undergraduate Research Exhibition Sponsored by Sigma Gamma Epsilon (Posters)

Presenting Author:

Authors:

Abstract:

The Cumberland Plateau in Tennessee, Kentucky, Alabama, and Georgia represents the southernmost extent of the Appalachian Basin—a composite retroarc foreland basin shaped by compressive forces from three successive Paleozoic orogenies, the most recent being the Alleghenian-Ouachita Orogeny. While the thermal evolution of the Northern Appalachian Basin is well documented, the post-depositional thermal history of the Southern Appalachian Basin, particularly the Cumberland Plateau, remains poorly constrained. To address this gap, we collected ten sandstone samples from exposed Mississippian and Pennsylvanian strata across the Cumberland Plateau in Tennessee. Fifty zircon grains (five per sample) were analyzed using (U-Th)/He detrital zircon (ZHe) thermochronometry to reconstruct the region’s post-depositional thermal history. ZHe results show significant variability in thermal resetting across different stratigraphic units: 21 of the 50 grains were reset. We used the thermal modeling software HeFTy to reconstruct time–temperature paths of the reset grains under geologically plausible constraints. Results indicate maximum burial temperatures varied across the plateau, reaching ~140–200°C, followed by cooling during ~320–250 Ma. This cooling likely reflects regional exhumation in the Southern Appalachian Basin during the late stages of the Alleghenian–Ouachita Orogeny.