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TitleGeological and geochemical characteristics of the Waconichi Formation east of the Lemoine auriferous volcanogenic massive sulphide deposit, Abitibi greenstone belt, Quebec
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AuthorBoulerice, A R; Ross, P -S; Mercier-Langevin, P
SourceTargeted Geoscience Initiative 4: Contributions to the understanding of volcanogenic massive sulphide deposit genesis and exploration methods development; by Peter, J M (ed.); Mercier-Langevin, P (ed.); Geological Survey of Canada, Open File 7853, 2015 p. 171-182, https://doi.org/10.4095/296551 (Open Access)
LinksCanadian Database of Geochemical Surveys, downloadable files
LinksBanque de données de levés géochimiques du Canada, fichiers téléchargeables
Year2015
PublisherNatural Resources Canada
Documentopen file
Lang.English
Mediaon-line; digital
RelatedThis publication is contained in Peter, J M; Mercier-Langevin, P; (2015). Targeted Geoscience Initiative 4: Contributions to the understanding of volcanogenic massive sulphide deposit genesis and exploration methods development, Geological Survey of Canada, Open File 7853
File formatpdf
ProvinceQuebec
NTS32G/09; 32G/10; 32G/15; 32G/16
AreaChibougamau
Lat/Long WENS -75.0000 -74.0000 50.0000 49.5000
Subjectseconomic geology; metallic minerals; structural geology; igneous and metamorphic petrology; geochemistry; Archean; volcanogenic deposits; sulphide deposits; alteration; metamorphism; mineral assemblages; mineralization; exploration guidelines; volcanic rocks; mineral deposits; gold; metallogeny; greenschist facies; deformation; chlorite; sericite; epidote; chloritoid; tectonic setting; hydrothermal alteration; hydrothermal deposits; lithology; rhyolites; dacites; andesites; basalts; gabbros; porphyries; geochemical analyses; trace element geochemistry; major element geochemistry; Abitibi greenstone belt; Lemoine deposit; Waconichi Formation; Lemoine Member; Precambrian
Illustrationslocation maps; cross-sections; plots; photographs
ProgramVolcanogenic Massive Sulfide Ore Systems, Targeted Geoscience Initiative (TGI-4)
Released2015 06 11
AbstractThe Lemoine Mine exploited a small but exceptionally rich auriferous volcanogenic massive sulphide body (0.76 Mt of ore grading 4.6 g/t Au). The deposit was located in the Lower Lemoine Member of the Waconichi Formation, in the Chibougamau area of the Archean Abitibi greenstone belt. The Lower Lemoine Member, which is mostly of tholeiitic magmatic affinity, is overlain by the Upper Lemoine Member comprising transitional basalt and transitional to calc-alkaline rhyolite. Field mapping, geochemical analyses, and detailed core logging of every accessible drillhole in the study area, east of the former mine, has helped to define the Lower Lemoine Member subunits and identify their mode of emplacement. The Lower Lemoine Member is composed of multiple extrusive subunits: from the bottom of the volcanic stratigraphy, the Alpha Rhyolite followed by the Lemoine Rhyolite, the Lemoine Dacite, the Lemoine Andesite, and the Hanging-wall Quartz and Feldspar Porphyry. A second, later, component of the Alpha Rhyolite intrudes the Lemoine Rhyolite locally. The Marelle Quartz and Feldspar Porphyry and the Coco Lake Rhyolite represent subvolcanic intrusions that form concordant sills at multiple stratigraphic levels in the Lower Lemoine Member. Preliminary results also indicate the potential presence and general location of previously unrecognized volcanic vents northeast of the Lemoine deposit, which may have been the site of paleohydrothermal fluid up-flow and may host additional mineralization. The precise location of the volcanic vents is the topic of ongoing work and will have implications for exploration for volcanogenic massive sulphides in the area and in similar settings elsewhere. Moreover, our work indicates that the Lemoine auriferous volcanogenic massive sulphide deposit is hosted in a felsic-dominated volcanic sequence comprising a significant portion of shallow intrusive rocks, defining a major thermal corridor over a large synvolcanic intrusion; conditions that may have contributed in forming such a base- and precious-metal-rich deposit.
GEOSCAN ID296551