New insights into the Appalachian Orogen from geology and geochronology along the Cape Ray fault zone, southwest Newfoundland

Research Article| January 01, 1996 New insights into the Appalachian Orogen from geology and geochronology along the Cape Ray fault zone, southwest Newfoundland B. Dubé; B. Dubé 1Quebec Geoscience Centre, Geological Survey of Canada, 2535 Laurier Boulevard, P.O. Box 7500, Ste-Foy, Quebec G1V 4C7, Canada Search for other works by this author on: GSW Google Scholar G. R. Dunning; G. R. Dunning 2Department of Earth Sciences, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3X5, Canada Search for other works by this author on: GSW Google Scholar K. Lauzière; K. Lauzière 3Quebec Geoscience Centre, Geological Survey of Canada, 2535 Laurier Boulevard, P.O. Box 7500, Ste-Foy, Quebec G1V 4C7, Canada Search for other works by this author on: GSW Google Scholar J. C. Roddick J. C. Roddick 4Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information B. Dubé 1Quebec Geoscience Centre, Geological Survey of Canada, 2535 Laurier Boulevard, P.O. Box 7500, Ste-Foy, Quebec G1V 4C7, Canada G. R. Dunning 2Department of Earth Sciences, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3X5, Canada K. Lauzière 3Quebec Geoscience Centre, Geological Survey of Canada, 2535 Laurier Boulevard, P.O. Box 7500, Ste-Foy, Quebec G1V 4C7, Canada J. C. Roddick 4Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1996) 108 (1): 101–116. https://doi.org/10.1130/0016-7606(1996)108<0101:NIITAO>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation B. Dubé, G. R. Dunning, K. Lauzière, J. C. Roddick; New insights into the Appalachian Orogen from geology and geochronology along the Cape Ray fault zone, southwest Newfoundland. GSA Bulletin 1996;; 108 (1): 101–116. doi: https://doi.org/10.1130/0016-7606(1996)108<0101:NIITAO>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Reverse-oblique overthrusting of high-grade Port aux Basques Gneiss over the lower-grade, supracrustal Windsor Point Group along the Cape Ray fault zone occurred during late Silurian to early Devonian time and is attributed to major oblique collision between Gondwanan and Laurentian continental blocks. New U-Pb zircon, 40Ar/39Ar, and K/Ar data limit the timing of this orogenic event. The megacrystic granitic phase of the Cape Ray Igneous Complex and the Cape Ray tonalite have been dated at 488 ± 3 Ma and 469 ± 2 Ma, respectively. A black rhyolite from the Windsor Point Group yielded an Ordovician age (453 +5/−4 Ma). A pretectonic gabbro sill within the Windsor Point Group, dated at 424 +4/−3 Ma, is cut by the Windowglass Hill granite dated at 424 ± 2 Ma. Synkinematic hornblende and biotite from the Grand Bay Complex mylonites of the Port aux Basques Gneiss have 40Ar/39Ar ages of 407 ± 4 Ma and 403 ± 4 Ma, respectively, which is indicative of a late Silurian–early Devonian age for the amphibolite grade deformation. These ages are compatible with a previously determined 415 Ma monazite age, interpreted as the time of peak metamorphism in the Port aux Basques Gneiss, and suggests rapid exhumation. The east-west flexure of the Cape Ray fault zone represents a tear fault accommodating differential shortening between the Cape Ray fault zone and the correlative fault system in central Newfoundland. Mid-Devonian granites (386 ± 3, 384 ± 2 Ma) intervene between the thrusting events and a younger sinistral transcurrent movement. This deformation and magmatic history can be correlated throughout the northern Appalachians along other major fault boundaries. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.