10 Deciphering Metamorphic Histories in Multiply-Deformed Terranes in the Piedmont and Blue Ridge

Thursday, 30 March 2017
1:00 PM - 5:00 PM
Potomac E

TECTONIC EVOLUTION OF THE WEDOWEE AND EMUCKFAW GROUPS OF THE SOUTHERN BLUE RIDGE OF EAST CENTRAL ALABMA

Paper number: 10-1
Program: Theme Sessions
Time: 1:00 PM – 1:20 PM

Authors

Abstract

The Ashland-Wedowee-Emuckfaw belt is a metamorphic composite terrane that formed along the Iapetus margin of Laurentia during the Cambrian through the Middle Ordovician. This terrane is found in the southernmost Appalachians of the northern Piedmont in east central Alabama and west central Georgia, in the Graham 7.5 minute quadrangle of Celbrune and Randolph Counties in east-central Alabama and Carroll and Heard Counties in west-central Georgia. The metasedimentary units, Wedowee Group, and Emuckfaw Group, of the southeastern Blue Ridge, have been studied in reconnaissance with no clear understanding of unit contacts or structural features. The nature of the major contact and correlations between the various units have been in debate. Past investigations have suggested the contact between the Wedowee and Emuckfaw Groups in the Graham quadrangle is a fault contact based on the presence of deformation and mild cataclasis. Recent detailed mapping of this quadrangle has provided a better understanding of the lithologic and unit contacts, as well as, the structural evolution of the Wedowee and Emuckfaw Groups. These groups are composed of metapelites, metaturbidites, and metavolcanics which have been interpreted to have formed in a Laurentian margin back-arc basin. The contact between the Wedowee and Emuckfaw Groups has been interpreted to be gradational in nature based on the absence of fault related structures. Both units are the same metamorphic grade and there is no discordance of planar or linear fabrics across the contact boundary. The rocks that make up these units have also recently been shown to contain Middle Ordovician detrital zircons and are correlated with units in Georgia which contain Middle Ordovician bimodal metavolcanic rocks.

Geological Society of America Abstracts with Programs. Vol. 49, No. 3

doi: 10.1130/abs/2017SE-290991

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