Thermal and tectonic evolution of the central and southern Appalachians: evidence from distribution, age, and origin of granitic rocks
The distribution and resolution of thermal events and associated igneous activity can discriminate between tectonic processes that form orogenic terrains, i.e., accretion of terranes, overthrusting of terranes versus thrust stacking within terranes. Reinterpretation of regional tectonics (Higgins et al., 1984) coupled with the authors interpretation of the age, origin, and distribution of granitic rocks suggest a very different mechanism for the evolution of the central and southern Appalachian orogenic belt. The Cambro-Ordovician magmatic arc (weakly bimodal) separated from the North American Margin by a Back arc basin, was thrust over the North American plate margin during the middle Ordovician. The Avalon terrane (Little River allochthon of Higgins et al., 1984) arrived during the late Silurian - but unlike earlier models that require subduction zone related with its arrival, the authors postulate strike-slip tectonics. The gabbro-diorite-syenite association in the Charlotte belt (Macon melange of Higgins) is probably related to grabens associated with the strike-slip accretion. Rocks of similar age (Siluro-Devonian) in the present day Blue Ridge and Inner Piedmont blocks are related to decompressional melting after the Ordovician thrusting. The high pressure metamorphism and associated melting show a range in ages indicating variations in uplift rates or thickness of the crust caused by the initial overthrusting, and do not require a discrete subduction or orogenic event. The Permo-Carboniferous igneous activity, and associated uplift and thrusting with a strike-slip component are related to oblique subduction and post-subduction collision processes.
- Research Organization:
- Virginia Polytechnic Institute and State Univ., Blackburg (USA)
- OSTI ID:
- 6070579
- Report Number(s):
- CONF-8510489-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
APPALACHIAN MOUNTAINS
OROGENESIS
PLATE TECTONICS
GRANITES
PETROGENESIS
AGE ESTIMATION
CAMBRIAN PERIOD
GEOLOGIC FAULTS
GEOLOGIC HISTORY
GEOLOGIC MODELS
MAGMATISM
METAMORPHISM
NORTH CAROLINA
ORDOVICIAN PERIOD
SUBDUCTION ZONES
VIRGINIA
FEDERAL REGION III
FEDERAL REGION IV
GEOLOGIC AGES
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
IGNEOUS ROCKS
MOUNTAINS
NORTH AMERICA
PALEOZOIC ERA
PLUTONIC ROCKS
ROCKS
TECTONICS
USA
580201* - Geophysics- Seismology & Tectonics- (1980-1989)
580300 - Mineralogy
Petrology
& Rock Mechanics- (-1989)