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Evidence for an orogen-parallel, normal-sense shear zone around the Chester Dome, Vermont; a possible template for gneiss dome formation in the New England Appalachians, USA

Paul M. Karabinos, Elizabeth S. Mygatt, Sean M. Cook and Matthew Student
Evidence for an orogen-parallel, normal-sense shear zone around the Chester Dome, Vermont; a possible template for gneiss dome formation in the New England Appalachians, USA (in From Rodinia to Pangea; the lithotectonic record of the Appalachian region, Richard P. Tollo (editor), Mervin J. Bartholomew (editor), James P. Hibbard (editor) and Paul M. Karabinos (editor))
Memoir - Geological Society of America (2010) 206: 183-203

Abstract

The New England Appalachians contain two north-south-trending sets of gneiss domes. The western belt, which includes the Chester Dome, contains 13 domes that expose either 1 Ga Laurentian basement rocks or ca. 475 Ma rocks of the Shelburne Falls Arc. The eastern belt contains 21 gneiss domes cored by either 600 Ma crust of possible Gondwanan affinity or ca. 450 Ma rocks of the Bronson Hill Arc. Domes in both belts are surrounded by Silurian and Early Devonian metasedimentary rocks, which were deposited in two north-south-trending basins before the Acadian Orogeny. The Chester Dome in southeastern Vermont, the main focus of this study, is an intensively studied, classic example of a mantled gneiss dome. Lower Paleozoic units around the Chester Dome are dramatically thinner than they are elsewhere in southern Vermont, and are locally absent. A strong spatial correlation between the highly attenuated mantling units and highly strained, mylonitic rocks suggests the presence of a ductile, normal-sense shear zone. Garnet-bearing rocks in the core of the dome record metamorphism during decompression of 2-3 kbar, whereas rocks above the high-strain zone were metamorphosed during nearly isobaric conditions. Strain markers and kinematic indicators suggest that extension occurred during northward extrusion of lower- to middle-crustal wedges of Proterozoic and Ordovician quartz-feldspar-rich gneisses below and up into a thick tectonic cover of Silurian mica-rich metasediments that had been transported westward in large-scale nappes. If the ductile, normal-sense shear zone was responsible for synmetamorphic decompression, as we propose, extrusion occurred at ca. 380 Ma.


ISSN: 0072-1069
Coden: GSAMAQ
Serial Title: Memoir - Geological Society of America
Serial Volume: 206
Title: Evidence for an orogen-parallel, normal-sense shear zone around the Chester Dome, Vermont; a possible template for gneiss dome formation in the New England Appalachians, USA
Title: From Rodinia to Pangea; the lithotectonic record of the Appalachian region
Author(s): Karabinos, Paul M.Mygatt, Elizabeth S.Cook, Sean M.Student, Matthew
Author(s): Tollo, Richard P.editor
Author(s): Bartholomew, Mervin J.editor
Author(s): Hibbard, James P.editor
Author(s): Karabinos, Paul M.editor
Affiliation: Williams College, Department of Geosciences, Williamstown, MA, United States
Affiliation: George Washington University, Geological Sciences Program, Washington, DC, United States
Pages: 183-203
Published: 2010
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 49
Accession Number: 2011-102854
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables, geol. sketch maps
N43°00'00" - N44°00'00", W73°00'00" - W72°00'00"
Secondary Affiliation: University of Memphis, USA, United StatesNorth Carolina State University, USA, United StatesWilliams College, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201152
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