Structural evolution of the Laurentian margin revisited (southern Quebec Appalachians): Implications for the Salinian orogeny and successor basins

Abstract

Research Article| January 01, 2002 Structural evolution of the Laurentian margin revisited (southern Quebec Appalachians): Implications for the Salinian orogeny and successor basins Alain Tremblay; Alain Tremblay 1INRS-Géoressources, Quebec Geoscience Centre, C.P. 7500, Quebec G1V 4C7, Canada Search for other works by this author on: GSW Google Scholar Sébastien Castonguay Sébastien Castonguay 2Geological Survey of Canada, Quebec Geoscience Centre, C.P. 7500, Quebec G1V 4C7, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Alain Tremblay 1INRS-Géoressources, Quebec Geoscience Centre, C.P. 7500, Quebec G1V 4C7, Canada Sébastien Castonguay 2Geological Survey of Canada, Quebec Geoscience Centre, C.P. 7500, Quebec G1V 4C7, Canada Publisher: Geological Society of America Received: 19 Mar 2001 Revision Received: 22 Aug 2001 Accepted: 12 Sep 2001 First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2002) 30 (1): 79–82. https://doi.org/10.1130/0091-7613(2002)030<0079:SEOTLM>2.0.CO;2 Article history Received: 19 Mar 2001 Revision Received: 22 Aug 2001 Accepted: 12 Sep 2001 First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Alain Tremblay, Sébastien Castonguay; Structural evolution of the Laurentian margin revisited (southern Quebec Appalachians): Implications for the Salinian orogeny and successor basins. Geology 2002;; 30 (1): 79–82. doi: https://doi.org/10.1130/0091-7613(2002)030<0079:SEOTLM>2.0.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 SocietyGeology Search Advanced Search Abstract The Laurentian margin of the Appalachians is divided into external and internal zones on the basis of metamorphic and structural contrasts. In the southern Quebec internal zone, Silurian to Early Devonian southeast-verging structures are superimposed on northwest-verging structures, whereas most of the external zone lacks such overprints. Regional backthrust faults define a major upper plate–lower plate boundary; the external-zone rocks are in the hanging wall, and internal-zone rocks are in the footwall. Metamorphic rocks with Silurian–Early Devonian 40Ar/39Ar ages (430–410 Ma) characterize the lower plate. To the east, the Saint-Joseph fault and the Baie Verte–Brompton line are southeast- dipping normal faults that crosscut the upper plate–lower plate boundary. Metamorphic rocks with Middle Ordovician 40Ar/39Ar ages (469–461 Ma) and rocks of the external zone both occur in the downthrown side of the Saint-Joseph fault and the Baie Verte–Brompton line. U-Pb and 40Ar/39Ar ages suggest that the northwest-verging structures are related to ophiolite obduction and crustal thickening during the Taconian orogeny (ca. 480–445 Ma), whereas the southeast-verging structures formed during Silurian–Early Devonian backthrusting and normal faulting. The revised structural interpretation has implications for the Salinian orogeny and involves (1) southeast-directed transport of the Taconian crustal wedge of the upper plate, followed by normal faulting and juxtaposition with the lower plate along the Saint-Joseph fault and the Baie Verte–Brompton line, and (2) the formation of fault-bounded sedimentary basins, such as the Connecticut Valley–Gaspé trough. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.