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In Canada and Adjacent Regions: 3 Ga to Present R Document généré le 30 sept. 2021 17:29 Geoscience Canada Igneous Rock Associations in Canada 3. Large Igneous Provinces (LIPs) in Canada and Adjacent Regions: 3 Ga to Present R. E. Ernst et K. L. Buchan Volume 31, numéro 3, september 2004 Résumé de l'article L'histoire de la Terre est ponctuée de nombreuses périodes de mise en place de URI : https://id.erudit.org/iderudit/geocan31_3ser01 forts volumes de magma mafiques. De tels magmas qui ne sont pas issus de zones d'expansion « normale » ou de subduction sont appelés Grandes Aller au sommaire du numéro provinces ignées (GPI), et celles-ci sont constituées de basaltes d'épanchements continentaux, de marges de fosse volcaniques, de plateaux océaniques, d'épanchements de basaltes de bassins océaniques, de crêtes sous-marines, et Éditeur(s) de chaînes de monts sous-marines. Peuvent également y être associées des suites de roches felsiques. Généralement, les GPI du Mésozoïque et du The Geological Association of Canada Cénozoïque sont les mieux préservées. Celles du Protérozoïque et du Paléozoïque sont généralement plus fortement érodées et sont constituées de ISSN vestiges de basaltes d'épanchement et des réseaux de conduits d'origine (réseaux géants de dykes, provinces de filons-couches et d'intrusifs stratifiées). 0315-0941 (imprimé) Dans l'Archéen, les meilleurs candidats sont représentés par les bandes de 1911-4850 (numérique) roches vertes à komatiites. De nombreuses GPI ont été associées à des épisodes de soulèvement régionaux, de dérives ou de fragmentations continentales, Découvrir la revue ainsi qu'à des crises climatiques. Elles peuvent servir de marqueurs temporels stratigraphiques et sont des cibles de première importance dans l'exploration de gisements de Cu-Ni-ÉGP. Les GPI sont aussi devenues des arguments très Citer cet article considérés dans le débat sur l'existence et la nature des panaches mantelliques. Le Canada possède de riches archives de GPI, et au moins 80 candidatures ont Ernst, R. E. & Buchan, K. L. (2004). Igneous Rock Associations in Canada 3. Large été isolées sur le territoire canadien et dans les régions adjacentes, leur âge Igneous Provinces (LIPs) in Canada and Adjacent Regions: 3 Ga to Present. délimitant une fourchette allant de 3 100 Ma à 17 Ma. Nous passons en revue Geoscience Canada, 31(3), 103–126. les liens proposés entre la suite des GDI canadiennes d'une part, et celle des panaches mantelliques, des fragmentations continentales, des soulèvements régionaux, et des gisements minéraux, d'autre part. Toutefois, vu le piètre état de caractérisation des unités mafiques au Canada, une campagne de caractérisation géochronologique, paléomagnétique et géochimique serait d'une valeur inestimable pour favoriser l'utilisation des GDI canadiennes pour nous aider à solutionner de grands problèmes géologiques. All rights reserved © The Geological Association of Canada, 2004 Ce document est protégé par la loi sur le droit d’auteur. L’utilisation des services d’Érudit (y compris la reproduction) est assujettie à sa politique d’utilisation que vous pouvez consulter en ligne. https://apropos.erudit.org/fr/usagers/politique-dutilisation/ Cet article est diffusé et préservé par Érudit. Érudit est un consortium interuniversitaire sans but lucratif composé de l’Université de Montréal, l’Université Laval et l’Université du Québec à Montréal. Il a pour mission la promotion et la valorisation de la recherche. https://www.erudit.org/fr/ GEOSCIENCE CANADA Volume 31 Number 3 September 2004 103 SERIES have been linked to regional-scale uplift, Dans l’Archéen, les meilleurs candidats continental rifting and breakup, and sont représentés par les bandes de climatic crises. They can be used as roches vertes à komatiites. De precisely dated time markers in the nombreuses GPI ont été associées à des stratigraphic record, and are key targets épisodes de soulèvement régionaux, de for Ni-Cu-PGE exploration. LIPs have dérives ou de fragmentations also become a focus in the debate on the continentales, ainsi qu’à des crises existence and nature of mantle plumes. climatiques. Elles peuvent servir de Canada has a rich record of marqueurs temporels stratigraphiques et LIPs. At least 80 candidates are recog- sont des cibles de première importance nized in Canada and adjacent regions, dans l’exploration de gisements de Cu- with ages ranging from 3100 to 17 Ma. Ni-ÉGP. Les GPI sont aussi devenues Igneous Rock Associa- We review proposed links between the des arguments très considérés dans le tions in Canada 3. LIP record of Canada and mantle débat sur l’existence et la nature des plumes, continental breakup, regional panaches mantelliques. Large Igneous Provinces uplift, and ore deposits. However, given Le Canada possède de riches (LIPs) in Canada and that many mafic units in Canada remain archives de GPI, et au moins 80 candi- Adjacent Regions: 3 Ga poorly characterized, a concerted datures ont été isolées sur le territoire geochronology campaign with integrated canadien et dans les régions adjacentes, to Present paleomagnetism and geochemistry would leur âge délimitant une fourchette allant be invaluable in expanding the applica- de 3 100 Ma à 17 Ma. Nous passons R.E. Ernst and K.L. Buchan tion of the Canadian LIP record to en revue les liens proposés entre la suite Geological Survey of Canada solving major geological problems. des GDI canadiennes d’une part, et celle 601 Booth Street des panaches mantelliques, des Ottawa, Ontario K1A 0E8 RÉSUMÉ fragmentations continentales, des [email protected] L’histoire de la Terre est ponctuée de soulèvements régionaux, et des nombreuses périodes de mise en place gisements minéraux, d’autre part. SUMMARY de forts volumes de magma mafiques. Toutefois, vu le piètre état de Earth history is punctuated by numerous De tels magmas qui ne sont pas issus de caractérisation des unités mafiques au periods during which large volumes of zones d’expansion « normale » ou de Canada, une campagne de mafic magma were emplaced. Such subduction sont appelés Grandes prov- caractérisation géochronologique, magmas not generated by a ‘normal’ inces ignées (GPI), et celles-ci sont paléomagnétique et géochimique serait spreading ridge or by subduction are constituées de basaltes d’épanchements d’une valeur inestimable pour favoriser termed Large Igneous Provinces (LIPs), continentaux, de marges de fosse l’utilisation des GDI canadiennes pour and consist of continental flood basalts, volcaniques, de plateaux océaniques, nous aider à solutionner de grands volcanic rifted margins, oceanic pla- d’épanchements de basaltes de bassins problèmes géologiques. teaus, ocean basin flood basalts, subma- océaniques, de crêtes sous-marines, et rine ridges, and seamount chains. de chaînes de monts sous-marines. INTRODUCTION Associated felsic rocks may also be Peuvent également y être associées des Large Igneous Provinces (LIPs) repre- present. LIPs of Mesozoic and Cenozoic suites de roches felsiques. Générale- sent voluminous magmatic events that age are typically the best preserved. ment, les GPI du Mésozoïque et du were not generated by a ‘normal’ spread- Those of Paleozoic and Proterozoic age Cénozoïque sont les mieux préservées. ing ridge or by subduction (Coffin and are usually more deeply eroded, and Celles du Protérozoïque et du Eldholm, 1994; 2001; Ernst et al., consist of flood basalt remnants and a Paléozoïque sont généralement plus 2004). They may be emplaced as often deep-level plumbing system (of giant fortement érodées et sont constituées de as once every 10 Ma (e.g. Coffin and dyke swarms, sill provinces and layered vestiges de basaltes d’épanchement et Eldholm, 2001), and time series analysis intrusions). In the Archean the most des réseaux de conduits d’origine of the LIP record for the past 3.5 Ga promising LIP candidates are greenstone (réseaux géants de dykes, provinces de suggests weak cyclicity (Isley and belts containing komatiites. Many LIPs filons-couches et d’intrusifs stratifiées). Abbott, 2002; Prokoph et al., 2004). 104 The most dramatic LIPs are emplaced The extrapolation of the LIP The compilation includes rapidly (within <10 Ma and often within record into the Archean is more specu- information on tectonic setting. Our only a few Ma). These include continen- lative. There are erosional remnants of criteria for determining setting rely tal flood basalts, seaward-dipping typical flood basalt provinces, namely heavily on dyke swarm geometry and its reflector sequences, oceanic plateaus, the Fortescue sequence of the Pilbara relationship to cratonic margins and ocean basin flood basalts. Conti- craton of Australia and the Ventersdorp (Fig. 3, Table 3). Events are inferred to nental flood basalts can be as large as sequence of the Kaapvaal craton of have a mantle plume origin if a giant several million cubic km (e.g. the southern Africa (Eriksson et al., 2002). radiating dyke swarm is present. Giant Siberian Traps; Reichow et al., 2002). However, most Archean volcanic rocks linear dyke swarms that extend into a The largest LIP is the Ontong Java occur as deformed and fault-fragmented craton (i.e. trend perpendicular to a oceanic plateau, which has a volume of packages termed greenstone belts. cratonic margin) are inferred to repre- 44.4 million cubic km (Coffin and Among these, the best candidates for sent an aulacogen-type swarm (‘failed- Eldholm, 2001) for combined extrusive LIPs are thick tholeiite sequences that arm’ type in Fahrig, 1987), and can also (6 million cubic km) and intrusive contain komatiites. The nature of be used to infer a plume origin with the components (Courtillot and Renne, Archean LIPs is discussed in greater plume centre situated at the edge of a 2003). The initial large-volume short- detail below. craton. By contrast, linear swarms that duration stage of magmatism of some LIPs are important 1) for testing parallel the edge of a craton may simply LIPs has been linked to the arrival of a plume and non-plume models for the be rift/breakup related (Ernst and mantle plume (e.g.
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