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TitleMajor Ore Types of the Lalor Auriferous VMS Deposit, Snow Lake, Manitoba
AuthorDuff, S; Caté, A; Hannington, M D; Mercier-Langevin, P; Ross, P -S
SourceProspectors and Developers Association of Canada, abstracts; 2014 p. 1
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20140454
PublisherNatural Resources Canada
MeetingProspectors and Developers Association of Canada; Toronto; CA; March 2-5, 2014
Mediaon-line; digital
File formatpdf
AreaSnow Lake; Lalor
Lat/Long WENS-102.0000 -98.0000 56.0000 54.0000
Subjectseconomic geology; mineral deposits; mineral assemblages; mineralization; gold; volcanogenic deposits; sulphides; deformation; metamorphism; alteration; hydrothermal alteration; volcanic rocks; igneous rocks; paragenesis; geochemical interpretations; Flin Flon Greenstone Belt; Lalor Deposit; Precambrian; Proterozoic
ProgramTargeted Geoscience Initiative (TGI-4), Volcanogenic Massive Sulfide Ore Systems
AbstractThe Lalor deposit is a newly discovered auriferous volcanogenic massive sulfide (VMS) deposit located on the East end of the Paleoproterozoic Flin Flon belt within a tectonostratigraphic succession known as the Snow Lake Arc (SLA) assemblage. With combined reserves and resources of 27.1 Mt at 2,82 g/t Au, 25,3 g/t Ag, 0.76% Cu and 5.16% Zn, Lalor stands out as an anomalously sized VMS deposit globally as well as the largest in the SLA. Hydrothermal activity along with superimposed polyphase deformation (D1-D3) and upper amphibolite metamorphism have produced an array of ore types; some of which are modified versions of ore types common in VMS deposits while others are atypical. Four main ore types, labelled 1 to 4, have been identified based on geochemistry and mineralogy. Type 1 massive sulfide (Zn±Cu±Ag) is the most common ore type and is characterized by coarse grained pyrite-sphalerite. Type 4 stringer sulfide (Au-Cu) contains chalcopyrite veins hosted in chlorite with sporadic patches of biotite and garnet. Although some recrystallization and remobilization has taken place, these two assemblages are typical of VMS mineralization as they respectively represent the low and high temperature zones. Type 2 mineralized chlorite carbonate schist (Ag-Au-Pb- Cu±Zn) contains stringers of galena and chalcopyrite with complex intergrowths of sulfosalts rimming electrum within a chlorite-dolomite matrix rich in calc-silicates. Type 3 low sulfide ore (Au±Ag) is a sparsely mineralized assemblage dominated by quartzbiotite- staurolite with minor pyrite and pyrrhotite but high Au grades. These latter two precious metal-rich ore types are uncharacteristic of VMS deposits and preliminary results indicate that they result from local remobilization of metals during prograde metamorphism. Studying the Lalor deposit ore types will allow for a better understanding of the original hydrothermal system and precious metal-rich VMS deposits, as well as the role of metamorphism and deformation in concentrating precious metals.