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TitleVolcanology, chemo-stratigraphy, geochronology, hydrothermal alteration and VMS potential of the Lemoine Member of the Waconichi Formation, Chibougamau district, Abitibi greenstone belt, Quebec
AuthorRoss, P -S; Boulerice, A; Mercier-Langevin, P; McNicoll, V
SourceMineralium Deposita 2019 p. 1-26, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20190104
PublisherSpringer Nature
Mediapaper; on-line; digital
File formatpdf (Adobe® Reader®); html
NTS32G/16SE; 32H/13SW
AreaChibougamau Mining District; Lake Chibougamau; Lac Monette; Lake Yvette
Lat/Long WENS -74.0825 -73.9997 49.8106 49.7875
Subjectseconomic geology; stratigraphy; tectonics; geochemistry; geochronology; geophysics; Archean; mineral deposits; mineral exploration; exploration guidelines; volcanogenic deposits; sulphide deposits; base metals; precious metals; zinc; copper; gold; silver; ore mineral genesis; mineralization; greenstone belts; tectonic evolution; volcanism; hydrothermal systems; hydrothermal alteration; chloritization; sericitization; carbonatization; epidotization; volcanology; core samples; intrusions; dykes; emplacement; thermal history; geophysical logging; petrographic analyses; lithogeochemistry; radiometric dating; uranium lead dating; zircon dates; bedrock geology; lithology; igneous rocks; volcanic rocks; lava flows; rhyolites; andesites; basalts; dacites; volcaniclastics; hyaloclastites; felsic volcanic rocks; felsic lavas; mafic volcanic rocks; intrusive rocks; quartz feldspar porphyries; gabbros; felsic intrusive rocks; diorites; structural features; faults; volcanic vents; field work; lithofacies; textural analyses; amygdules; trace element geochemistry; mineral assemblages; geochemical anomalies; Abitibi Greenstone Belt; Roy Group; Waconichi Formation; Lemoine Member; Lac Doré Complex; Precambrian
Illustrationslocation maps; geoscientific sketch maps; cross-sections; tables; pie charts; photographs; photomicrographs; geochemical plots; Concordia diagrams; plots; schematic representations
ProgramTargeted Geoscience Initiative (TGI-5) Gold ore systems
Released2019 04 25
AbstractThe Archean Lemoine volcanogenic massive sulfide (VMS) deposit in the Chibougamau mining district (Abitibi greenstone belt) is one of the richest to have been mined in the world (758,070 t of ore at 4.17% Cu, 9.51% Zn, 4.56 g/t Au, and 83.73 g/t Ag). It is hosted by the ~ 2728 Ma Lemoine Member of the Waconichi Formation. Field mapping, core logging, petrography, lithogeochemistry, and U-Pb zircon geochronology helped define the stratigraphy, volcanic architecture, and hydrothermal history of the Lemoine Member east of the former mine, and document the complex relationships between effusive, intrusive, and hydrothermal activity. There, the Lemoine Member is informally divided into a 700 to 900-m-thick lower part (~ 45% extrusive and ~ 55%intrusive) and a 600 to 700-m-thick upper part (~ 85%extrusive and ~ 15%intrusive). Extrusive units in the lower part have a tholeiitic to transitional magmatic affinity and are dominantly felsic, whereas those of the upper part have a transitional to calc-alkaline affinity and are dominantly mafic. The effusive felsic units are mostly interpreted as one or more lobe-hyaloclastite flow(s) per unit. Possible volcanic vent sites for all effusive units were identified. Three types of hydrothermal alteration are present in the lower part of the Lemoine Member in the study area, from stratigraphic base to top: chlorite-sericite, sericite-chlorite, and sericite-chlorite-carbonate±epidote. Within this broad pattern, three paleo-hydrothermal upflow zones are proposed, and some correspond with known base and precious metal anomalies and/or proposed volcanic vent locations.

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