Timing of peak metamorphism and deformation along the Appalachian margin of Laurentia in Newfoundland: Silurian, not Ordovician

• Main Authors: Cawood, Peter Anthony, DUNNING, G R, LUX, D, VANGOOL, J A M
• Format: Article in Journal/Newspaper
• Language: English
• Published: 1994
• Subjects: ALLOCHTHON; BASEMENT; TERRANES; Corner Brook; Newfoundland
• Online Access: https://risweb.st-andrews.ac.uk/portal/en/researchoutput/timing-of-peak-metamorphism-and-deformation-along-the-appalachian-margin-of-laurentia-in-newfoundland-silurian-not-ordovician(4b9580d7-1dca-4e1c-97e8-9122e792aed6).html; http://www.scopus.com/inward/record.url?scp=0028194144&partnerID=8YFLogxK

U/Pb and Ar/Ar isotopic age data from the Corner Brook Lake region of the eastern Appalachian Humber zone in western Newfoundland indicate that regional deformation and peak amphibolite-facies metamorphism are Early Silurian. A lower limit on deformation is provided by a U/Pb zircon age of 434 +2/-3 Ma for a pegmatite that is affected by the regional foliation and is interpreted to be syntectonic. Monazite and rutile from a garnet-kyanite-staurolite schist, which records peak-metamorphic conditions and in which porphyroblasts have overgrown the regional foliation, gave U/Pb ages of 430 +/-2 Ma and 437 +/-6 Ma, respectively. Ar/Ar cooling ages for hornblende from amphibolites and muscovite from psammitic and pelitic schists range from 430 to 420 Ma. A Silurian age for deformation and metamorphism of the Laurentian margin is coincident with the timing of similar events along the Newfoundland Gondwana margin and suggests that the Silurian was a period of major continent-continent collision.