Field Excursions from the 2021 GSA Section Meetings

The 2021 GSA Northeastern, Southeastern, joint North-Central/South-Central, and Cordilleran Section Meet-ings were held virtually in spring 2021 during continued restrictions on travel and large gatherings due to COVID-19. Eleven groups put together field guides, taking participants on treks to states from Connecticut to Nevada in the United States, to Mexico, and to Italy, and covering topics as varied as bedrock geologic map-ping, geochemistry, paleodrainage, barrier islands, karst, spring systems, a southern Appalachian transect, Ordo-vician and Mississippian stratigraphy, high-energy events, Cretaceous arc granites and dextral shear zones, and Mesoproterozoic igneous rocks. This volume serves as a valuable resource for those wishing to discover, learn more about, and travel through these geologically fascinating areas.
Tectonism and metamorphism along a southern Appalachian transect across the Blue Ridge and Piedmont, USA†
*Emails: Stowell, corresponding author: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]
*Emails: Stowell, corresponding author: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]
*Emails: Stowell, corresponding author: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]
*Emails: Stowell, corresponding author: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]
*Emails: Stowell, corresponding author: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]
*Emails: Stowell, corresponding author: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]
*Emails: Stowell, corresponding author: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]
*Emails: Stowell, corresponding author: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]
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Published:September 24, 2021
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CiteCitation
Harold Stowell*, Elizabeth Bollen*, Matthew P. McKay*, J. Ryan Thigpen*, Hannah F. Dickson*, Jeffrey R. Madden*, Cobi Fiechtner*, Adelie Ionescu*, 2021. "Tectonism and metamorphism along a southern Appalachian transect across the Blue Ridge and Piedmont, USA", Field Excursions from the 2021 GSA Section Meetings, Joan Florsheim, Christian Koeberl, Matthew P. McKay, Nancy Riggs
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ABSTRACT
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.
- Alabama
- Allegheny Group
- Appalachians
- Blue Ridge Province
- Carboniferous
- field trips
- garnet group
- geochemistry
- geochronology
- geotraverses
- metal ores
- metamorphism
- Middle Pennsylvanian
- mines
- nesosilicates
- North America
- orthosilicates
- Paleozoic
- Pennsylvanian
- Piedmont
- road log
- silicates
- Sm/Nd
- Southern Appalachians
- Taconic Orogeny
- tectonics
- Tennessee
- United States
- Ashland Supergroup
- Mad Indian Group
- Wedowee Group
- Cutnose Formation
- Pumpkinvine Creek Formation
- Emuckfaw Group
- Josie Leg Formation
- Neoacadian
- Shooting Creek Schist