Geochemistry of Deformed and Hydrothermally Mobilized Magmatic Ni-Cu-PGE Ores at the Garson Mine, Sudbury

Abstract

Research Article| March 01, 2014 Geochemistry of Deformed and Hydrothermally Mobilized Magmatic Ni-Cu-PGE Ores at the Garson Mine, Sudbury* Joshua Mukwakwami; Joshua Mukwakwami † Mineral Exploration Research Centre, Department of Earth Sciences, Laurentian University, 933 Ramsey Lake Road, Sudbury, Ontario P3E 2C6, Canada †Corresponding author: e-mail, jx_mukwakwami@laurentian.ca Search for other works by this author on: GSW Google Scholar C. Michael Lesher; C. Michael Lesher Mineral Exploration Research Centre, Department of Earth Sciences, Laurentian University, 933 Ramsey Lake Road, Sudbury, Ontario P3E 2C6, Canada Search for other works by this author on: GSW Google Scholar Bruno Lafrance Bruno Lafrance Mineral Exploration Research Centre, Department of Earth Sciences, Laurentian University, 933 Ramsey Lake Road, Sudbury, Ontario P3E 2C6, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information Joshua Mukwakwami † Mineral Exploration Research Centre, Department of Earth Sciences, Laurentian University, 933 Ramsey Lake Road, Sudbury, Ontario P3E 2C6, Canada C. Michael Lesher Mineral Exploration Research Centre, Department of Earth Sciences, Laurentian University, 933 Ramsey Lake Road, Sudbury, Ontario P3E 2C6, Canada Bruno Lafrance Mineral Exploration Research Centre, Department of Earth Sciences, Laurentian University, 933 Ramsey Lake Road, Sudbury, Ontario P3E 2C6, Canada †Corresponding author: e-mail, jx_mukwakwami@laurentian.ca Publisher: Society of Economic Geologists Received: 17 Sep 2012 Accepted: 23 May 2013 First Online: 09 Mar 2017 Online ISSN: 1554-0774 Print ISSN: 0361-0128 © 2014 Society of Economic Geologists. Economic Geology (2014) 109 (2): 367–386. https://doi.org/10.2113/econgeo.109.2.367 Article history Received: 17 Sep 2012 Accepted: 23 May 2013 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Joshua Mukwakwami, C. Michael Lesher, Bruno Lafrance; Geochemistry of Deformed and Hydrothermally Mobilized Magmatic Ni-Cu-PGE Ores at the Garson Mine, Sudbury. Economic Geology 2014;; 109 (2): 367–386. doi: https://doi.org/10.2113/econgeo.109.2.367 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 The Garson Ni-Cu-platinum group element (PGE) deposit is a deformed, overturned, contact-type deposit along the contact between the Sudbury Igneous Complex and underlying rocks of the Huronian Supergroup in the South Range of the 1850 Ma Sudbury structure. The main Garson orebodies occur along steeply S dipping ductile shear zones, which formed as D1 north-over-south amphibolite facies thrust zones that were rotated and overturned during buckling of the Sudbury Igneous Complex. The shear zones were reactivated as south-over-north greenschist facies reverse shear zones during D2. The mineralization is primarily composed of pyrrhotite-pentlandite-chalcopyrite-magnetite, occurring as four main types: (1) disseminated to matrix-textured sulfides in Main Mass norite and slivers of norite within shear zones, (2) semimassive breccia ore within the shear zones, (3) quartz-calcite-sulfide veins spatially associated with breccia ores, and (4) Cu-Pd-Pt-Au–rich “footwall-type” mineralization in the nearby Garson Ramp deposit. Garson disseminated sulfides and breccia ores have relatively low Pd/Ir ratios and restricted ranges of Ni tenors and Fe/Ni ratios, very similar to those of undeformed disseminated sulfides and contact-type massive ores at the less deformed Creighton deposit. This suggests that the mobilization of the breccia ores by ductile plastic flow during D1 and D2 did not significantly alter their original magmatic geochemical signatures. Garson breccia ores are slightly depleted in Cu-Pt-Pd-Au and slightly enriched in Rh-Ru-Ir relative to disseminated sulfides, similar to other contact-type deposits at Sudbury. In contrast, quartz-calcite-sulfide veins at Garson are characterized by very low Rh-Ru-Ir abundances and very high Pd/Ir ratios, consistent with their mobilization and deposition from metamorphic-hydrothermal fluids. Despite being strongly enriched in Cu-Pd-Pt-Au, there are too few of these veins to account for the broad depletion in Cu-Pd-Pt-Au from the main mass of breccia ores, suggesting that the breccia ores are monosulfide solid solution cumulates that left a residual sulfide melt represented by the Cu-Pd-Pt-Au–rich ores in the Garson Ramp deposit. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.