Hepburn intrusive suite: Peraluminous plutonism within a closing back-arc basin, Wopmay orogen, Canada

Abstract

Research Article| March 01, 1989 Hepburn intrusive suite: Peraluminous plutonism within a closing back-arc basin, Wopmay orogen, Canada André E. Lalonde André E. Lalonde 1Ottawa-Carleton Geoscience Centre, Department of Geology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information André E. Lalonde 1Ottawa-Carleton Geoscience Centre, Department of Geology, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1989) 17 (3): 261–264. https://doi.org/10.1130/0091-7613(1989)017<0261:HISPPW>2.3.CO;2 Article history 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 André E. Lalonde; Hepburn intrusive suite: Peraluminous plutonism within a closing back-arc basin, Wopmay orogen, Canada. Geology 1989;; 17 (3): 261–264. doi: https://doi.org/10.1130/0091-7613(1989)017<0261:HISPPW>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 SocietyGeology Search Advanced Search Abstract Within the Hepburn metamorphic-plutonic internal zone of the Wopmay orogen (Northwest Territories, Canada) there are two chronologically and petrologically distinct plutonic associations. The more voluminous of the two, the older 1.885 Ga Hepburn intrusive suite, includes rocks ranging in composition from gabbro to granite, peraluminous granite dominating. The younger 1.855 Ga neighboring Bishop intrusive suite (also gabbro to granite) represents the waning stages of a well-documented calc-alkaline arc, the Great Bear magmatic zone. The petrological distinctions between the two suites are all late-acquired features imposed primarily by contrasting environments of emplacement. Hepburn magmas were intruded within a closing, dominantly sedimentary, back-arc basin. Magma emplacement was synchronous with crustal imbrication, regional metamorphism, and translation of the basin-fill units onto Archean crust. Significant assimilation of sedimentary host rocks by the rising Hepburn magmas occurred, whereas the postregional metamorphism emplacement of the Bishop magmas precluded similar assimilation. The gabbroic contribution observed in the Hepburn intrusive suite is interpreted to reflect a mantle-derived precursor inherited from the back-arc rifting event that immediately preceded emplacement of the suite. This content is PDF only. Please click on the PDF icon to access. 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.