Truncation and translation of Appalachian promontories; mid-Paleozoic strike-slip tectonics and basin initiation

Accreted terranes of the Appalachian Iapetan and peri-Gondwanan realms display structural trends that are mainly concordant with promontories and embayments in the Laurentian margin, indicating that during accretion, the shape of the continental margin acted as a template around which accreted terra...

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Bibliographic Details
Published in:Geology (Boulder) 2009-06, Vol.37 (6), p.487-490
Main Authors: Hibbard, James, Waldron, John W. F
Format: Article
Language:English
Subjects:
accretion
Appalachian Phase
Appalachians
Basins
Canada
Carboniferous
continental margin
crust
crustal thinning
Devonian
Eastern Canada
extension
faults
Geology
Laurentia
Maritimes Basin
middle Paleozoic
Mountains
Newfoundland
Newfoundland and Labrador
North America
North Carolina
orogenic belts
orogeny
Paleozoic
Permian
Plate tectonics
promontories
Rheic Ocean
South Carolina
strike-slip faults
structural analysis
Structural geology
tectonics
terranes
transcurrent faults
United States
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Summary:Accreted terranes of the Appalachian Iapetan and peri-Gondwanan realms display structural trends that are mainly concordant with promontories and embayments in the Laurentian margin, indicating that during accretion, the shape of the continental margin acted as a template around which accreted terranes were molded. In North Carolina and Newfoundland, post-accretion transcurrent motion appears to be recorded by displaced outboard portions of promontories, no longer concordant with those in Laurentia. A bend in structural trends confined to the peri-Gondwanan realm at the North Carolina-South Carolina state line is interpreted to represent the dextrally displaced outboard portion of the Virginia promontory. In Newfoundland, the Hermitage flexure is interpreted as a dextrally displaced Laurentian promontory that originated along strike to the northeast. In both places, promontories were truncated and dextrally translated for approximately 220-250 km by a Devonian-Mississippian orogen-parallel transcurrent system, which may well have extended for the length of the eastern Laurentian margin. South of the nearby St. Lawrence promontory, extreme thinning of Appalachian crust beneath the Maritimes Basin is consistent with extension at a releasing stepover. Estimates of extension are consistent with those obtained from promontory offsets.
ISSN:0091-7613
1943-2682
DOI:10.1130/G25614A.1