Komatiitic Sills and Multigenerational Peperite at Dundonald Beach, Abitibi Greenstone Belt, Ontario: Volcanic Architecture and Nickel Sulfide Distribution

• Published in: Economic Geology
• Main Authors: Houlé, Michel G., Gibson, H. L., Lesher, C. M., Davis, P. C., Cas, R. A. F., Beresford, S. W., Arndt, Nicholas
• Other Authors: Mineral Exploration Research Centre, Laurentian University, Ottawa-Carleton Geoscience Centre, University of Ottawa Ottawa, PRECAMBRIAN GEOSCIENCE SECTION, ONTARIO GEOLOGICAL SURVEY, Carleton University, First Nickel Inc., School of Geosciences, Monash University Clayton, Laboratoire de Géodynamique des Chaines Alpines (LGCA), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2008
• Subjects: Cape Smith; House Lake; Kola Peninsula; McIntosh; Pechenga; kola peninsula
• Online Access: https://insu.hal.science/insu-00354512; https://doi.org/10.2113/gsecongeo.103.6.1269

International audience The density and the tectonic stresses in the deep crust and the physical properties of komatiitic magmas determine the level to which they will rise, but once in the near-surface environment, the density and rheology of the near-surface rocks (consolidated and dense lava flows and sedimentary rocks versus unconsolidated sedimentary or volcaniclastic deposits) govern whether they will be emplaced as lava flows, invasive flows, or sills. Where near-surface strata are competent (i.e., flow-dominated or consolidated sedimentary and/or volcaniclastic successions), komatiitic magma erupts as flows that form extensive lava shields (e.g., Kambalda). However, where near-surface strata are not competent (i.e., unconsolidated volcaniclastic- and/or sediment-dominated successions), komatiitic magmas typically are emplaced as high-level sills that increase the bulk density of the volcano-sedimentary pile and eventually allow the eruption of lava and the construction of complex sub-volcanic-volcanic lava shields (e.g., Dundonald and Shaw dome, Abitibi belt; Raglan, Cape Smith belt; Pechenga, Kola Peninsula; Thompson Ni belt, Manitoba). The latter environment is illustrated in the volcano-sedimentary succession in Dundonald Township, which is only weakly metamorphosed and deformed and superbly exposed in glacially polished outcrops. The volcano-sedimentary succession in this area comprises (from base to top) (1) the McIntosh formation, composed of a succession of pillowed and massive intermediate volcanic flows; (2) the Dundonald formation, composed of a lower section of komatiite sills, argillites, and felsic volcaniclastic deposits and an upper section of komatiite flows, komatiitic sills, and pillowed intermediate volcanic flows; and (3) the Frederick House Lake formation, composed of massive and pillowed mafic flows. The distribution and thickness of argillites and felsic volcaniclastic rocks define a synvolcanic graben in which the Dundonald South and Alexo Ni-Cu-(PGE) deposits occur within the ...