Rhenium-Osmium Geochronology of Arsenopyrite in Meguma Group Gold Deposits, Meguma Terrane, Nova Scotia, Canada: Evidence for Multiple Gold-Mineralizing Events

Abstract

Research Article| September 01, 2005 Rhenium-Osmium Geochronology of Arsenopyrite in Meguma Group Gold Deposits, Meguma Terrane, Nova Scotia, Canada: Evidence for Multiple Gold-Mineralizing Events Ryan M. Morelli; Ryan M. Morelli Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E3 †Corresponding author: e-mail, [e-mail] Search for other works by this author on: GSW Google Scholar Robert A. Creaser; Robert A. Creaser Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E3 Search for other works by this author on: GSW Google Scholar David Selby; David Selby Department of Earth Sciences, University of Durham, Durham, United Kingdom DH1 3LE Search for other works by this author on: GSW Google Scholar Daniel J. Kontak; Daniel J. Kontak Nova Scotia Department of Natural Resources, P.O. Box 698, Halifax, Nova Scotia, Canada B3J 3M8 Search for other works by this author on: GSW Google Scholar Richard J. Horne Richard J. Horne Nova Scotia Department of Natural Resources, P.O. Box 698, Halifax, Nova Scotia, Canada B3J 3M8 Search for other works by this author on: GSW Google Scholar Author and Article Information Ryan M. Morelli Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E3 Robert A. Creaser Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E3 David Selby Department of Earth Sciences, University of Durham, Durham, United Kingdom DH1 3LE Daniel J. Kontak Nova Scotia Department of Natural Resources, P.O. Box 698, Halifax, Nova Scotia, Canada B3J 3M8 Richard J. Horne Nova Scotia Department of Natural Resources, P.O. Box 698, Halifax, Nova Scotia, Canada B3J 3M8 †Corresponding author: e-mail, [e-mail] Publisher: Society of Economic Geologists Received: 29 Jun 2004 Accepted: 19 Sep 2005 First Online: 09 Mar 2017 Online ISSN: 1554-0774 Print ISSN: 0361-0128 © 2005 Society of Economic Geologists, Inc. Economic Geology (2005) 100 (6): 1229–1242. https://doi.org/10.2113/gsecongeo.100.6.1229 Article history Received: 29 Jun 2004 Accepted: 19 Sep 2005 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Ryan M. Morelli, Robert A. Creaser, David Selby, Daniel J. Kontak, Richard J. Horne; Rhenium-Osmium Geochronology of Arsenopyrite in Meguma Group Gold Deposits, Meguma Terrane, Nova Scotia, Canada: Evidence for Multiple Gold-Mineralizing Events. Economic Geology 2005;; 100 (6): 1229–1242. doi: https://doi.org/10.2113/gsecongeo.100.6.1229 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 SocietyEconomic Geology Search Advanced Search Abstract Rhenium-osmium geochronology using arsenopyrite was undertaken for three gold deposits in the Meguma terrane, Nova Scotia, Canada, in order to better constrain their age of formation and to assess the utility of arsenopyrite for dating similar deposits globally. Analyses of arsenopyrite from bedding-concordant veins from The Ovens locality, southwest Meguma terrane, yield a precise Re-Os isochron age of 409 ± 5 Ma. Arsenopyrite analyses from a bedding-discordant vein at this locality indicate an identical Re-Os age of 407 ± 4 Ma. Saddle-reef veins from the Dufferin deposit, northeast Meguma terrane, contain arsenopyrite with a precise Re-Os isochron age of 380 ± 3 Ma. The lack of common Os in some arsenopyrite samples from both The Ovens and Dufferin permit calculation of single mineral model ages for each deposit, which are identical to those determined using the isochron method. Initial Os compositions for the two vein types at The Ovens suggest a predominately crustal source of Os in the mineralizing fluids, whereas a less radiogenic initial Os composition for arsenopyrite from Dufferin does not as clearly define a crustal metal source. At a third locality, the Touquoy deposit, the Re-Os systematics of arsenopyrite associated with disseminated gold mineralization do not define a precise formation age, possibly as a result of mixing of Re and Os derived from the mineralizing fluid and the shale host rock.The Re-Os ages of arsenopyrite indicate that there were at least two distinct periods of gold deposition in the Meguma terrane coinciding with widespread tectonothermal events: regional deformation and metamorphism associated with Acadian orogenesis, and widespread generation of meta- and peraluminous granites and high-grade metamorphism within the basement rocks under the Meguma terrane. The ca. 407 Ma age for The Ovens arsenopyrite provides the best estimate for the timing of regional Acadian deformation in the Meguma terrane and is slightly older than previous estimates based solely on 40Ar/39Ar dating. 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