New late Precambrian-Cambrian U-PB zircon ages for zoned intrusives in the western Carolina terrane, Spartanburg and Union Counties, South Carolina
- Univ. of South Carolina, Aiken, SC (United States). Physical Sciences
- Rice Univ., Houston, TX (United States). Geology and Geophysics
The geology of the western Carolina terrane comprises zoned mafic-ultramafic intrusive complexes intruding a volcanic pile of basalts and basaltic andesites; this package is interpreted to represent an episode of intra-arc rifting prior to regional metamorphism and foliation formation. New U-Pb zircon ages from the Mean Crossroads complex in northwestern South Carolina along the central Piedmont suture confirm relative ages obtained by detailed mapping. Two foliated meta-diorites yield U-Pb dates of 580 Ma, interpreted to be crystallization ages. A foliated meta-quartz diorite yields a U-Pb date of 535 Ma interpreted to be a crystallization age. These ages are broadly contemporary with those inferred by other workers for the Battleground Formation in the type locality of the Kings Mountain belt. An undeformed, unmetamorphosed diorite intruding these metamorphosed zoned complex intrusives also yields an age of 535 Ma. Hence the authors believe that intra-arc rifting and regional metamorphism both occurred c. 535 Ma. While petrographic and Ar-Ar studies support subsequent regional metamorphic overprint(s), or at least static recrystallization and/or uplift through hornblende-biotite-muscovite blocking temperatures for Ar in mid- to late-Paleozoic time, the 535 Ma, undeformed, unmetamorphosed intrusive suggest late Precambrian regional metamorphism and deformation was the event responsible for regional greenschist-lower amphibolite facies metamorphism and foliation formation in this area of the Piedmont. This seems to contradict correlations with middle Ordovician fabric elements in the eastern Piedmont as well as the idea that this metamorphism and fabric development are related to presumed early Paleozoic accretion of the Carolina arc to Laurentia. They have also dated a foliated megacrystic granite that cuts the central Piedmont suture (325 Ma, U-Pb zircon), and the Bald Rock granite (326 Ma, U-Pb zircon).
- OSTI ID:
- 5951365
- Report Number(s):
- CONF-9304188-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 25:4; Conference: 42. annual Geological Society of America (GSA) Southeastern Section meeting, Tallahassee, FL (United States), 1-2 Apr 1993; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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