Author ORCID Identifier

https://orcid.org/0000-0003-3654-8759

Year of Publication

2021

Degree Name

Master of Science (MS)

Document Type

Master's Thesis

College

Arts and Sciences

Department/School/Program

Earth and Environmental Sciences (Geology)

First Advisor

Dr. J. Ryan Thigpen

Abstract

Channel and escape flow, or lower crustal ductile flow and redirection from orogen-normal to orogen-parallel flow, are among the most impactful concepts introduced to explain shortening accommodation in large, hot orogens. In the Inner Piedmont (IP), southern Appalachians, channel and escape flow were proposed to have occurred during the Neo-Acadian (376–340 Ma) orogeny. However, the polymetamorphic history of the southern Appalachians makes it difficult to isolate thermal and deformational events for process-focused studies necessary to test these ideas in the IP. To address this, we used in situ laser ablation split stream (LASS) monazite U-Pb geochronology alongside new garnet chemical data and existing P-T-t data to define the footprints of Paleozoic metamorphism in the southern Appalachians. Eastern Blue Ridge (BR) data indicate primarily Taconic (~458 Ma) with secondary Neo-Acadian metamorphism (373–335 Ma) whereas the western IP shows only Neo-Acadian metamorphism (~356 Ma). This indicates that the Brevard fault zone (BFZ) was a thermal and potentially rheological boundary during Neo-Acadian metamorphism, supporting earlier interpretations that the BFZ acted as a buttress to channel flow. Additionally, the southeastern IP records mostly Neo-Acadian (380–350 Ma) and secondary Alleghanian (339–325 Ma) metamorphism, allowing each orogenic event to be spatially separated.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2021.333

Funding Information

This study was supported in 2018, prior to the author's attending University of Kentucky, as well as from 2019 to 2021 by the National Science Foundation grant entitled "Fundamental controls on mid-crustal 'escape' flow in orogenic systems", NSF-EAR-1802730.

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