The Alleghanian orogeny in the southern Appalachians: Perspective from the hinterland

Conference · Wed Jan 01 04:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5588602

Secor, Jr, D T; Barker, C A; Boland, I B; Pray, J R; Steinke, T R; West, T E ^[1]; Dallmeyer, R D ^[2]; Dennis, A J ^[3]; Maher, H D ^[4]; Wright, J E ^[5]; Sacks, P E

---

1. Univ. of South Carolina, Columbia, SC (United States). Dept. of Geological Science
2. Univ. of Georgia, Athens, GA (United States). Dept. of Geology
3. Univ. of South Carolina, Aiken, SC (United States). Dept. of Physical Science
4. Univ. of Nebraska, Omaha, NE (United States). Dept. of Geography and Geology
5. Rice Univ., Houston, TX (United States). Dept. of Geology and Geophysics

Along the Savannah River, the southeastern edge of the exposed Appalachian orogen provides a record of Alleghanian tectonothermal activity spanning 275--315 Ma. The earliest known structure is the Modoc fault extending 250 km along the Fall Line from Lake Murray, SC to Forsyth, GA. The Modoc fault is interpreted as a low-angle normal fault kinematically related to delamination during collision between Gondwana and Laurentia. During 275--315 Ma, the Modoc fault and adjacent terranes were deformed by NW vergent folds that are interpreted to have been kinematically linked to shortening in the foreland VIA a regional decollement. Prior to 275 Ma, the Modoc fault formed along the SE side of the Savannah River terrane. Ar-40/Ar-39 muscovite plateau ages in the Savannah River terrane define a 275 Ma horizontal isothermal surface which has not been folded or tilted. The Alleghanian orogeny in the hinterland is therefore interpreted to have terminated at ca. 275 Ma. The variety of Alleghanian structures in the hinterland may be a consequence of indentor tectonics and partitioning of displacement among coeval thrust, normal, and strike-slip faults. Taken together, the structures are interpreted to indicate relative convergence and counterclockwise rotation of Gondwana during the Alleghanian orogeny.

• OSTI ID: 5588602
• Report Number(s): CONF-921058--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 24:7
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
AGE ESTIMATION
APPALACHIAN BASIN
DEFORMATION
DEVELOPED COUNTRIES
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
GEORGIA
ISOTOPE RATIO
MOTION
NORTH AMERICA
OROGENESIS
RIVERS
ROTATION
SAVANNAH RIVER
SEDIMENTARY BASINS
SOUTH CAROLINA
STREAMS
SURFACE WATERS
TECTONICS
USA