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GEOREF RECORD

From the Alleghanian to the Atlantic; extensional collapse of the southernmost Appalachian Orogen

Chong Ma, David A. Foster, Willis E. Hames, Paul A. Mueller and Mark G. Steltenpohl
From the Alleghanian to the Atlantic; extensional collapse of the southernmost Appalachian Orogen
Geology (Boulder) (February 2019) 47 (4): 367-370

Abstract

Understanding the thermal evolution of the Alleghanian orogen in the southernmost Appalachians (southeastern United States) is key to understanding the orogenic collapse and extensional tectonics that led to the breakup of Pangea. Cooling-age contours derived from (super 40) Ar/ (super 39) Ar ages of hornblende, muscovite, and biotite from granitic plutons and their country rocks show a regional pattern of younging toward the southeast. This cooling-age gradient, along with the distribution of normal faults, discontinuities in metamorphic grade, and rifting of the South Georgia basin suggest that the southernmost Appalachian crystalline rocks between the Brevard fault and the Coastal Plain unconformity were exhumed as the lower plate of an extensional detachment fault system. The Suwannee and Charleston terranes likely preserve part of the upper plate. These features represent the postorogenic collapse of the southernmost Appalachians probably along an extensive detachment fault system in the Permian-Middle Triassic. This episode of extension may have played a crucial role in thinning the continental crust to its current thickness and likely was the first stage of extension that eventually led to the breakup of Pangea and formation of the Atlantic Ocean.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 47
Serial Issue: 4
Title: From the Alleghanian to the Atlantic; extensional collapse of the southernmost Appalachian Orogen
Affiliation: Auburn University, Department of Geosciences, Auburn, AL, United States
Pages: 367-370
Published: 20190228
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 39
Accession Number: 2019-024201
Categories: Structural geologyGeochronology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2019126
Illustration Description: illus. incl. geol. sketch maps
N32°00'00" - N35°00'00", W86°00'00" - W80°30'00"
Secondary Affiliation: University of Florida, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201914
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