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Tuesday, April 24 • 3:05pm - 3:25pm
The Burnsville Fault: Determining The Southwest Extension And Relation To The Hayesville Fault

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The Appalachian orogen records a complex history, including three mountain building events associated with the assembly of Pangea: the Ordovician Taconic, Silurian-Devonian Acadian, and the late Paleozoic Alleghenian orogenies. The dextral strike slip Burnsville fault runs through western North Carolina (WNC) and is the only Acadian structure in WNC. It was previously mapped between Asheville and Spruce Pine, NC. The Burnsville fault separates the Eastern Blue Ridge (EBR) and the Western Blue Ridge (WBR), which includes ~1 billion year old Grenville basement rocks. This boundary formed during the Taconic orogeny and was reactivated during the Acadian orogeny as the Burnsville fault. The southwest extension of the Burnsville fault is unclear. The Hayesville fault to the southwest of Asheville has previously been documented as a Taconic structure that, like the Burnsville fault, separates the EBR from the WBR. There is a level of uncertainty regarding the relationship between the Burnsville and Hayesville faults due to similar metamorphic conditions during the Taconic and Acadian as well as Alleghanian overprinting. This study tested the hypothesis that the Burnsville fault overprinted the Hayesville fault by mapping the Hayesville fault in the southwest corner of the Clyde 7.5 minute quadrangle, NC. Shear sense indicators, vertical to slightly southeast dipping mylonite trending ~N45°E, and a shallow to horizontal plunging stretching lineation indicate ductile dextral strike slip faulting. Temperatures obtained from dynamic quartz recrystallization that occurred during deformation showed temperatures of ~500° C with slight overprinting from temperatures of less than 400° C. Findings for this shear zone are consistent to what has previously been documented in the Burnsville shear zone to the northeast. Detailed field mapping and microstructure analysis demonstrates that, at least locally, the Burnsville fault possibly continues along the northwest extension of the Hayesville fault.


Tuesday April 24, 2018 3:05pm - 3:25pm PDT
014 Zeis Hall