Geology of North American Palladium Ltd.'s Roby Zone Deposit, Lac des Iles

Abstract

Research Article| January 01, 2001 Geology of North American Palladium Ltd.’s Roby Zone Deposit, Lac des Iles M.J. LAVIGNE; M.J. LAVIGNE North American Palladium Ltd., Thunder Bay, Ontario, Canada, P7E 3Z5 Search for other works by this author on: GSW Google Scholar M.J. MICHAUD M.J. MICHAUD SRK Consulting, Toronto, Ontario, Canada, M5H 2T7 Search for other works by this author on: GSW Google Scholar Exploration and Mining Geology (2001) 10 (1-2): 1–17. https://doi.org/10.2113/10.1-2.1 Article history received: 15 Jan 2002 accepted: 15 Jul 2002 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation M.J. LAVIGNE, M.J. MICHAUD; Geology of North American Palladium Ltd.’s Roby Zone Deposit, Lac des Iles. Exploration and Mining Geology 2001;; 10 (1-2): 1–17. doi: https://doi.org/10.2113/10.1-2.1 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 SocietyExploration and Mining Geology Search Advanced Search Abstract North American Palladium Ltd. operates its Lac des Iles open pit palladium mine 85 km north of the city of Thunder Bay, Ontario. The Roby Zone deposit occurs within the mafic/ultramafic Lac des Iles Intrusive Complex (LDI-IC), which was created by multiple pulses of magma of varying composition within several closely spaced chambers. Chaotic lithological distribution, the presence of magmatic breccias, and the rarity of rhythmic layering suggest a dynamic intrusive environment with disruptive magma pulses. As of December 31, 2001, measured and indicated resources for the 950 m long by 815 m wide Roby Zone deposit totalled 159 Mt grading 1.55 g/t Pd, 0.17 g/t Pt, 0.12 g/t Au, 0.05% Cu, and 0.05% Ni at a palladium cut-off grade of 0.7 g/t. The Roby Zone contains an additional 73 Mt of inferred resources at similar grades.The Roby Zone is dominated by varitextured gabbro containing pipes and pods of breccia, and large blocks (~60 m across) of varying lithology. Mineralization at Lac des Iles occurs as: (1) a PGE-and base metal-rich magmatic matrix of breccia (breccia ore); (2) mineralized dikes or sills (gabbronorite in North Roby ore); (3) lower-grade mineralization in varitextured units that are host to the distinctive breccia ore and envelope the North Roby ore; and (4) high-grade mineralization associated with strong silicate alteration exemplified by high-grade ore.The close spatial association of the mineralized breccias with both varitextured units and silicate alteration leads to an interpretation that the energetic magma that created breccia was charged with a dissolved fluid, and that this deuteric fluid exsolved at high temperatures to migrate through crystal mush, enhancing crystallization along its pathways, resulting in variable grain size. This transformation occurred at high temperature and produced sulfide-poor, varitextured gabbro-hosted mineralization exemplified by some of the mineralization in the North Roby Zone, and also found throughout the Roby Zone. The association of hydrous silicate alteration with mineralization can be explained by continuing fluid migration during cooling and continued metal transport. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.