Thermal and tectonic evolution of the central and southern Appalachians: evidence from distribution, age, and origin of granitic rocks

Conference · Tue Jan 01 04:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6070579

Sinha, A K; Guy, R; Hund, E; Tamburro, E

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-
• Conference Information: Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580201* -- Geophysics-- Seismology & Tectonics-- (1980-1989)
580300 -- Mineralogy
Petrology
& Rock Mechanics-- (-1989)
AGE ESTIMATION
APPALACHIAN MOUNTAINS
CAMBRIAN PERIOD
FEDERAL REGION III
FEDERAL REGION IV
GEOLOGIC AGES
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC HISTORY
GEOLOGIC MODELS
GEOLOGIC STRUCTURES
GRANITES
IGNEOUS ROCKS
MAGMATISM
METAMORPHISM
MOUNTAINS
NORTH AMERICA
NORTH CAROLINA
ORDOVICIAN PERIOD
OROGENESIS
PALEOZOIC ERA
PETROGENESIS
PLATE TECTONICS
PLUTONIC ROCKS
ROCKS
SUBDUCTION ZONES
TECTONICS
USA
VIRGINIA