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GEOREF RECORD

The Prospect Rock Thrust; western limit of the Taconian accretionary prism in the northern Green Mountain Anticlinorium, Vermont

Peter J. Thompson and Thelma B. Thompson
The Prospect Rock Thrust; western limit of the Taconian accretionary prism in the northern Green Mountain Anticlinorium, Vermont (in The Appalachian forelands and platform NATMAP project; geological bridges of Eastern Canada, Denis Lavoie (editor), Michel Malo (editor) and Alain Tremblay (editor))
Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre (February 2003) 40 (2): 269-284

Abstract

This paper presents evidence for an early Taconian, west-directed fault in northern Vermont, the Prospect Rock thrust, which represents the trace of the contact between the Taconian oceanic accretionary prism (Dunnage Zone) and less allochthonous, continental margin rocks (Humber Zone). Mapping at 1:24000 over the last decade has led to reassessment of units within the Camels Hump Group, resulting in newly defined lithotectonic packages: the Green Mountain slice and the Prospect Rock slice. Rocks in these slices may be of similar age, but those in the Green Mountain slice were originally deposited as more proximal sediments and remained on the Humber side of the subduction zone, whereas those in the Prospect Rock slice were transferred by underplating to the accretionary prism. Both slices contain ultramafics. Motion on the Prospect Rock thrust (D (sub 1) ) preceded Taconian garnet-grade metamorphism and subsequent east-directed back-folding. However, D (sub 1) structures were diachronous across the orogen. Late Taconian (D (sub 2) ) structures record a change from east-verging back-folds in northern Vermont and southern Quebec to west-verging folds farther south. The Prospect Rock thrust does not correspond exactly to Cameron's line nor to the Baie Verte-Brompton line as originally defined. However, our understanding of the geometry of the Prospect Rock thrust demonstrates that the Dunnage Zone extends farther west than previously recognized and may also explain features farther to the east.


ISSN: 0008-4077
EISSN: 1480-3313
Coden: CJESAP
Serial Title: Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre
Serial Volume: 40
Serial Issue: 2
Title: The Prospect Rock Thrust; western limit of the Taconian accretionary prism in the northern Green Mountain Anticlinorium, Vermont
Title: The Appalachian forelands and platform NATMAP project; geological bridges of Eastern Canada
Author(s): Thompson, Peter J.Thompson, Thelma B.
Author(s): Lavoie, Deniseditor
Author(s): Malo, Micheleditor
Author(s): Tremblay, Alaineditor
Affiliation: University of New Hampshire, Earth Sciences Department, Durham, NH, United States
Affiliation: Commission Geologique du Canada, Centre Geoscientifique, Quebec City, QC, Canada
Pages: 269-284
Published: 200302
Text Language: English
Summary Language: French
Publisher: National Research Council of Canada, Ottawa, ON, Canada
References: 60
Accession Number: 2003-037490
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sect., geol. sketch maps
N44°00'00" - N45°00'00", W73°00'00" - W72°00'00"
Secondary Affiliation: INRS-Eau Terre Environnement, CAN, Canada
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 200312
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