| Titre | Alteration and ore assemblages of the LaRonde Zone 5 (LZ5) deposit and Ellison mineralized zones, Doyon-Bousquet-LaRonde mining camp, Abitibi, Quebec |
| Télécharger | Téléchargements |
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| Licence | Veuillez noter que la Licence du gouvernement
ouvert - Canada remplace toutes les licences antérieures. |
| Auteur | Boily-Auclair, É; Mercier-Langevin, P; Ross, P -S; Pitre, D |
| Source | Commission géologique du Canada, Dossier public 8867, 2022, 48p., https://doi.org/10.4095/329637  Accès ouvert |
| Image |  |
| Année | 2022 |
| Éditeur | Ressources naturelles Canada |
| Document | dossier public |
| Lang. | anglais |
| DOI | https://doi.org/10.4095/329637 |
| Media | en ligne; numérique |
| Référence reliée | Photo(s) de RNCan dans cette publication |
| Formats | pdf |
| Province | Québec |
| SNRC | 32D/01; 32D/02; 32D/07; 32D/08 |
| Lat/Long OENS | -78.5833 -78.4000 48.2833 48.2333 |
| Sujets | gisements minéraux; or; argent; gîtes sulfureux; prospection minière; genèse des minerais; minéralisation; contrôles des minerais; altération; auréoles d'altération; assemblages de minéraux; zonéographie;
boudinage; inclusions; roches hôtes; géologie du substratum rocheux; lithologie; roches ignées; roches volcaniques; volcanoclastique; rhyolites; basaltes; andésites; dacites; roches intrusives; roches sédimentaires; caractéristiques structurales;
failles; zones de failles; dôme; cadre tectonique; évolution tectonique; métamorphisme; déformation; plissement; foliation; système hydrothermal; altération hydrothermale; magmatisme; volcanisme; fluage; dynamique des fluides; filons; veinules;
eprentes; lentilles; mise en place; enrichissement des minéraux; recristallisation; perméabilité; porosité; datation radiométrique; datation au uranium-plomb; analyses géochimiques; analyses des éléments majeurs; analyses stratigraphiques;
corrélations stratigraphiques; établissement de modèles; métallogénie; pétrogenèse; Archéen; Ceinture d'Abitibi Greenstone ; Camp minier de Doyon-Bousquet-Laronde; Groupe de Blake River ; Formation de Bousquet ; Zone de faille de Larder Lake-Cadillac
; Zone de déformation de Destor-Porcupine ; géologie économique; minéralogie; géologie structurale; stratigraphie; tectonique; géochronologie; géochimie; Nature et environnement; Sciences et technologie; Précambrien |
| Illustrations | cartes de localisation; cartes géolscientiques généralisées; coupes de corrélation; graphiques géochimiques; photographies; photomicrographies; coupes schématiques transversales; coupes
lithologiques; profils géochimiques; graphiques; tableaux |
| Programme | Initiative géoscientifique ciblée (IGC-6) Systèmes minéralisés |
| Diffusé | 2022 02 22 |
| Résumé | (disponible en anglais seulement)
The LaRonde Zone 5 (LZ5) mine is part of the Doyon-Bousquet-LaRonde mining camp and is located in the southern part of the Abitibi greenstone belt in
northwestern Quebec. The LZ5 deposit consists of three stacked mineralized corridors: Zone 4, Zone 4.1, and Zone 5. Zones 4 and 4.1 are discontinuous satellite mineralized corridors, whereas Zone 5 represents the main mineralized body.
The
mineralized zones of the LZ5 deposit and adjacent Ellison property (Ellison A and B zones) are hosted in the strongly-deformed, 2699-2695 Ma transitional to calcalkaline, intermediate to felsic, volcanic and volcaniclastic rocks of the Bousquet
Formation upper member, which is part of the Blake River Group (2704-2695 Ma). Zones 4, 4.1, and 5 at the LZ5 mine are hosted in intermediate volcanic and volcaniclastic rocks of the Westwood andesitic to rhyodacitic unit (unit 5.1a), which forms the
base of the upper member of the Bousquet Formation. The Ellison Zone A is hosted higher up in the stratigraphic sequence within a newly described intermediate volcanic unit. The Ellison Zone B is hosted in felsic volcanic and volcaniclastic rocks of
the Westwood feldsparphyric rhyolite dome (subunit 5.3a-(b)).
Mineralization in all three zones of the LZ5 deposit consists of discordant networks of millimeter- to centimeter-thick pyrite ±chalcopyrite ±sphalerite ±pyrrhotite veins and veinlets
(10-20 % of the volume of the rock) and, to a lesser extent, very finely disseminated pyrite and boudinaged veins (less than or equal to 5 vol. % each) in strongly altered host rocks. Gold commonly occurs as microscopic inclusions in granoblastic
pyrite and at the triple junction between recrystallized grains. The veins, stockworks, and disseminations were intensely folded and transposed in the steeply south-dipping, east-west trending S2 foliation. The vein network is at least partly
discordant to the stratigraphy. A distal alteration halo envelops the LZ5 mineralized corridors and consists of a sericite-carbonate-chlorite- feldspar ±biotite assemblage. A proximal sericite-carbonate-chlorite-pyrite-quartz- feldspar-biotite
±epidote alteration assemblage is present within the LZ5 mineralized zones.
A local proximal alteration assemblage of sericite-quartz-pyrite is also locally developed within Zone 4 and Zone 5 of the LZ5 deposit. Mass gains in Fe2O3 (t) and K2O,
and mass losses in CaO, MgO, Na2O, and locally SiO2, are characteristic of the LZ5 alteration zones. The Ellison zone A and B are similar to LZ5 in terms of style of mineralization, but thin (10-20 cm) veins or bands of semi-massive to massive,
finely recrystallized disseminated pyrite (0.1-1 mm) are distinctive. Chalcopyrite and sphalerite are also slightly more abundant in the mineralized corridors of the Ellison property and are usually associated with elevated gold grades. The zones are
also slightly richer than at LZ5 in terms of gold and silver content, but narrower and less continuous in general. The Ellison Zone A is characterized by gains in Fe2O3 (t) and K2O and losses in CaO, MgO, Na2O, and SiO2. Gains in Fe2O3 (t) and local
gains in K2O, MgO, and MnO, and losses in CO2, Na2O, P2O5, and SiO2, characterize the felsic host rocks of the Zone B corridor.
The style of mineralization at LZ5 (pyrite ±chalcopyrite veins and veinlets, ±disseminated pyrite with low base metal
content), its setting (i.e. in rocks of intermediate composition at the base of the upper member of the Bousquet Formation), and the geometry of its ore zones (stacked lenses of sulfide veins and veinlets, without massive sulfide lenses) differ from
the other major deposits of the Doyon-Bousquet-LaRonde mining camp.
Despite these differences, this study indicates that the LZ5 and Ellison mineralized corridors are of synvolcanic hydrothermal origin and have most likely been formed by
convective circulation of seawater below the seafloor. An influx of magmatic fluids from the Mooshla synvolcanic intrusive complex or its parent magma chamber could explain the Au enrichment at LZ5, as has been suggested for other deposits of the
camp. Evidence for a pre-deformation synvolcanic mineralization at LZ5 includes ductile deformation and recrystallization of the sulfides, the stacked nature of its ore zones, subconcordant alteration halos that envelop the mineralized corridors,
evidence that the mineralized system was already active when the LZ5 lenses were deposited and control on mineralization by primary volcanic features such as the permeability and porosity of the volcanic rocks. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Ce rapport présente les résultats de l'étude des zones minéralisées du projet LaRonde Zone 5 et de la propriété adjacente Ellison (Abitibi,
Québec), avec une emphase particulière sur la minéralogie et la signature géochimique des zones d'altération hydrothermale associées au minerai, et présente un modèle génétique pour ce type de minéralisation aurifère. |
| GEOSCAN ID | 329637 |
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