Exhumation mechanisms of eclogite in the southern Appalachians and evidence for post-Cherokee orogeny movement

The Bakersville, NC eclogite bodies in the southern Appalachians record peak metamorphic conditions of the Taconic orogeny. These high-pressure rocks are surrounded by amphibolite-facies rocks of the Ashe Metamorphic Suite. The eclogite zircons record ages of 460.7 +/- 3.2 Ma, temperatures of 703-775 °C, and the zircon REE patterns indicate that they grew at eclogite-facies conditions. The amphibolite zircons record ages of 415 +/- 3.8 Ma, temperatures of 614-669 °C, and their REE patterns indicate that the zircons did not grow in the presence of garnet, which are present at eclogite conditions. These differences suggest that the amphibolites are not retrograded eclogite and that the Bakersville eclogite was emplaced into lower-grade rocks during its exhumation, consistent with either driven cavity flow or plunger-driven exhumation models. The Silurian-Devonian age of the amphibolite zircon may record crustal thickening and burial related to post-Cherokee orogeny movement along the Burnsville fault.