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TitreGeology and Au enrichment processes at the Paleoproterozoic Lalor auriferous volcanogenic massive sulphide deposit, Snow Lake, Manitoba
TéléchargerTéléchargement (publication entière)
AuteurCaté, A; Mercier-Langevin, P; Ross, P -S; Duff, S; Hannington, M D; Dubé, B; Gagné, S
SourceTargeted 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. 131-145, https://doi.org/10.4095/296549
LiensCanadian Database of Geochemical Surveys, downloadable files
LiensBanque de données de levés géochimiques du Canada, fichiers téléchargeables
Année2015
ÉditeurRessources naturelles Canada
Documentdossier public
Lang.anglais
DOIhttps://doi.org/10.4095/296549
Mediaen ligne; numérique
Référence reliéeCette publication est contenue dans 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, Commission géologique du Canada, Dossier public 7853
Formatspdf
ProvinceManitoba
SNRC63K/16
Lat/Long OENS-102.0000 -98.0000 56.0000 54.0000
SujetsArchéen; gîtes volcanogènes; gîtes sulfureux; altération; métamorphisme; assemblages de minéraux; minéralisation; directives d'exploration; roches volcaniques; gisements minéraux; or; sulfures; déformation; altération hydrothermale; roches ignées; paragenèse; interprétations géochimiques; altération hydrothermale; Ceinture de Flin Flon Greenstone ; géologie économique; stratigraphie; Précambrien; Protérozoïque
Illustrationslocation maps; plots; photomicrographs
ProgrammeÉtude des gîtes de sulfures massifs volcaniques, Initiative géoscientifique ciblée (IGC-4)
Diffusé2015 06 11
Résumé(disponible en anglais seulement)
The Paleoproterozoic Lalor auriferous volcanogenic massive sulphide deposit, located in the Snow Lake mining camp, Manitoba, is hosted in a complex volcanic package referred to as the Lalor volcanic succession. The deposit consists of stratigraphically and structurally stacked Zn-rich, Au-rich, and Cu-Au-rich ore lenses. The host volcanic succession comprises mafic to felsic tholeiitic to calc-alkaline extrusive to intrusive volcanic rocks of the ca. 1.89 Ga Lower Chisel subsequence, and the ore is hosted in both mafic and felsic rocks. Atypical of the other Zn-rich deposits of the Snow Lake district, the Lalor deposit is not situated at the top of the Lower Chisel subsequence, but is at a slightly lower stratigraphic position. The volcanic rocks that host the deposit were affected by intense and laterally extensive ore-related hydrothermal alteration. These altered rocks were subsequently subjected to syndeformational amphibolitegrade metamorphism that resulted in the development of distinct minerals and metamorphic mineral assemblages of varying composition from variably altered precursor lithologies. Five distinct alteration- and metasomatism- related chemical associations (K, K-Mg-Fe, Mg-Fe, Mg-Ca, and Ca) are recognized based on mineralogical (mineral assemblages) and bulk geochemical compositions. Mapping of the host volcanic rocks and ore-related mineral assemblages and chemical associations at Lalor indicates the following: 1) the Zn-rich massive sulphide lenses are preferentially associated with the low- to high-temperature K and Mg- Ca alteration zones; 2) the Cu-Au-rich zones, which occur at depth, stratigraphically below the Zn-rich mineralization, are hosted in transposed, presumably originally discordant high-temperature Mg-Fe altered rocks; and 3) Au has been in part locally remobilized into low-strain sites that are not now spatially associated with any particular chemical association. The Lalor volcanic succession is affected by polyphase deformation that has strongly influenced the geometry of the Lalor deposit. Pre-D2 (synvolcanic?) deformation is evidenced by the abrupt termination of the intensely altered Lalor volcanic succession to the southwest and the presence of chemically distinctive and unaltered volcanic rocks of the Western succession. The present geometry of the deposit is largely controlled by D2 deformational structures with important stretching (L2), flattening (S2), and structural staking (F2 folding and syn- to late-D2 transposition and shearing). The D2 deformation and associated peak metamorphic conditions are thought to be responsible for the local remobilization of Au sulphosalts and some sulphides.
GEOSCAN ID296549