Tectonism and metamorphism along a southern Appalachian transect across the Blue Ridge and Piedmont, USA

Harold Stowell, Elizabeth Bollen, Matthew P. McKay, J. Ryan Thigpen, Hannah F. Dickson, Jeffrey R. Madden, Cobi Fiechtner, Adelie Ionescu

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

1 Scopus citations


The Appalachian Mountains expose one of the most-studied orogenic belts in the world. However, metamorphic pressure-temperature-time (P-T-t) paths for reconstructing the tectonic history are largely lacking for the southernmost end of the orogen. In this contribution, we describe select field locations in a rough transect across the orogen from Ducktown, Tennessee, to Goldville, Alabama. Metamorphic rocks from nine locations are described and analyzed in order to construct quantitative P-T-t paths, utilizing isochemical phase diagram sections and garnet Sm-Nd ages. P-T-t paths and garnet Sm-Nd ages for migmatitic garnet sillimanite schist document high-grade 460–411 Ma metamorphism extending south from Winding Stair Gap to Standing Indian in the Blue Ridge of North Carolina. In the Alabama Blue Ridge, Wedowee Group rocks were metamorphosed at biotite to staurolite zone, with only local areas of higher-temperature metamorphism. The Wedowee Group is flanked by higher-grade rocks of the Ashland Supergroup and Emuckfaw Group to the northwest and southeast, respectively. Garnet ages between ca. 357 and 319 Ma indicate that garnet growth was Neoacadian to early Alleghanian in the Blue Ridge of Alabama. The P-T-t paths for these rocks are compatible with crustal thickening during garnet growth.

Original languageEnglish
Title of host publicationGSA Field Guides
EditorsJoan Florsheim, Christian Koeberl, Matthew P. McKay, Nancy Riggs
Number of pages38
StatePublished - Sep 24 2021

Publication series

NameGSA Field Guides

Bibliographical note

Funding Information:
The authors acknowledge support from the National Science Foundation (EAR 1119039), which helped establish, and the University of Alabama, which provided operating funds, for the UA RadIs laboratory. Assistance from Robert D. Hatcher Jr. and Arthur Merschat is greatly appreciated. Thorough and constructive reviews by Clinton Barineau and Jamie Levine greatly improved this work.

Publisher Copyright:
© 2021 The Geological Society of America. All rights reserved.

ASJC Scopus subject areas

  • Geology
  • Earth-Surface Processes
  • Stratigraphy
  • Paleontology


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