| Titre | Precious metal enrichment processes in volcanogenic massive sulphide deposits - a summary of key features, with an emphasis on TGI-4 research contributions |
| Télécharger | Téléchargements |
| |
| Licence | Veuillez noter que la Licence du gouvernement
ouvert - Canada remplace toutes les licences antérieures. |
| Auteur | Mercier-Langevin, P; Hannington, M D; Dubé, B; Piercey, S J; Peter, J M ; Pehrsson, S J |
| Source | Targeted Geoscience Initiative 4: Contributions to the understanding of volcanogenic massive sulphide deposit genesis and exploration methods development; par Peter, J M (éd.); Mercier-Langevin, P (éd.); Commission géologique du Canada, Dossier public
7853, 2015 p. 117-130, https://doi.org/10.4095/296548  Accès
ouvert |
| Liens | Canadian Database of Geochemical Surveys, downloadable files
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| Liens | Banque de données de levés géochimiques du Canada,
fichiers téléchargeables
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| Image |  |
| Année | 2015 |
| Éditeur | Ressources naturelles Canada |
| Document | dossier public |
| Lang. | anglais |
| DOI | https://doi.org/10.4095/296548 |
| Media | en ligne; numérique |
| Référence reliée | Cette publication est contenue dans Targeted
Geoscience Initiative 4: Contributions to the understanding of volcanogenic massive sulphide deposit genesis and exploration methods development |
| Formats | pdf |
| Province | Nunavut; Territoires du Nord-Ouest; Nouveau-Brunswick; Manitoba; Québec; Terre-Neuve-et-Labrador |
| SNRC | 75I; 75J; 75K; 75L; 75M; 75N; 75O; 75P; 76; 85I; 85J; 85O; 85P; 86A; 86B; 86G; 86H; 86I/01; 86I/02; 86I/03; 86I/04; 86I/05; 86I/06; 86I/07; 86I/08; 86I/09; 86I/10; 86I/11; 86I/14; 86I/15; 86I/16; 86P/01;
86P/02; 86P/07; 86P/08; 86P/09; 86P/16; 21O/01; 21O/02; 21O/03; 21O/06; 21O/07; 21O/08; 21O/09; 21O/10; 21O/11; 21P/04; 21P/05; 21P/12; 63K/16; 32G/09; 32G/10; 32G/15; 32G/16; 12A/10; 12H/16 |
| Région | Izok Lake; Grand lac des Esclaves; Halfmile Lake; Bathurst; Grand-Sault; Nepisiguit River; Snow Lake; Lalor; Chibougamau; Red Indian Lake; Baie Verte Peninsula |
| Lat/Long OENS | -116.0000 -104.0000 68.0000 62.0000 |
| Lat/Long OENS | -66.5000 -65.7500 47.7500 47.1333 |
| Lat/Long OENS | -102.0000 -98.0000 56.0000 54.0000 |
| Lat/Long OENS | -75.0000 -74.0000 50.0000 49.5000 |
| Lat/Long OENS | -56.5833 -56.5833 48.6667 48.5000 |
| Lat/Long OENS | -56.0217 -56.0217 49.9317 49.8658 |
| Sujets | Archéen; gîtes volcanogènes; gîtes sulfureux; altération; métamorphisme; assemblages de minéraux; minéralisation; directives d'exploration; roches volcaniques; gisements minéraux; or; argent; métaux
précieux; géologie économique; Précambrien |
| Illustrations | diagrammes schématiques; coupes transversales; organigrammes |
| Programme | Initiative géoscientifique ciblée (IGC-4) Étude des gîtes de sulfures massifs volcaniques |
| Diffusé | 2015 06 11; 2023 03 17 |
| Résumé | (disponible en anglais seulement)
Volcanogenic massive sulphide deposits contain precious metals (Au, Ag) that can be present in high to low grades and total amounts; depending on tonnage and/or
precious metal grade, such deposits can represent desirable exploration targets. Globally, deposits with >3.46 g/t Au are considered "auriferous", those with >-31 t of contained Au are "anomalous", and those with both large tonnage (>-31 t Au) and
high gold grade (>3.46 g/t Au) are considered "Au-rich". There are still no clear statistical criteria to determine thresholds that would define "anomalous" Ag grades and/or total amount of Ag in volcanogenic massive sulphide deposits, as grades vary
widely depending on the nature of the host succession. Two general requisites may explain anomalous primary precious metal budgets in volcanogenic massive sulphide deposits: 1) inherently Au- and/or Ag-enriched source rocks and fluids due to a
specific geodynamic setting or heritage and/or to magmatic input, and 2) efficient transport (favourable ligands) and precipitation (e.g. boiling/phase separation, zone refining). These two requisites, which are of different scales, may or may not be
mutually exclusive. Late or "secondary" Au- and/or Ag-enrichment in volcanogenic massive sulphide deposits can be due to the superposition of mineralizing systems of a different style (e.g. epithermal, intrusion-related, orogenic, etc.). Weathering
processes (e.g. supergene enrichment) on the seafloor or on land can also significantly modify the distributions of precious metals in a volcanogenic massive sulphide deposit.
Volcanogenic massive sulphide deposits in volcanic belts that formed
in pericratonic settings or on older crust basement in the early stages of rifting are commonly slightly better endowed in precious metals than those formed in belts or settings with no or limited basement influence. Gold-rich and auriferous VMS are
preferentially associated with calc-alkaline or transitional magmatic successions, with andesite-dacite-rhyodacite- rhyolite magmatic suites and with thick (10s to 100s of m) felsic volcanic packages. Evidence for a magmatic input and of deposition
in response to boiling/phase separation include the presence of complex mineral assemblages comprising sulphosalts, sulphides, native elements, and anomalous trace element signatures (e.g. enrichment in the "epithermal suite" of elements
Au-As-Sb-Ag-Hg and/or in felsic magmaassociated elements Bi-W-Te-In-Sn). A laterally extensive sericitic (phyllic) }siliceous alteration halo, a zone of intense aluminous (argillic to advanced argillic-style) alteration, and heterogeneous Au and Ag
distributions and mineralogical residence sites within or near the sulphide bodies are also indicators of a possible magmatic contribution of Au, Ag, and other metals, such as Te and Bi, or metal deposition due to boiling in VMS systems. |
| Sommaire | (Résumé en langage clair et simple, non publié)
L'Initiative géoscientifique ciblée (IGC-4) est un programme géoscientifique fédéral de collaboration qui fournit à l'industrie les
connaissances géoscientifiques et les techniques novatrices de prochaine génération dont elle a besoin pour mieux détecter les gîtes minéraux enfouis, réduisant ainsi certains risques liés à l'exploration. Ce volume synthétise 12 activités de
recherche complétées dans le cadre du projet sur les systèmes minéralisés sulfures massifs volcanogènes de l'IGC-4. Ces activités portaient notamment sur les gisements de types SMV enrichis en métaux précieux (Au, Ag) ainsi que sur le développement
de vecteurs et de méthodes non-conventionnelles de détection pour les gisements de SMV. |
| GEOSCAN ID | 296548 |
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