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TitleElucidating mineralizing fluid pathways from the geophysical responses to hydrothermal alteration: integrated 3D modelling of lithogeochemical, petrophysical, seismic and magnetotelluric data, Lalor volcanogenic massive sulphide deposit, Manitoba
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AuthorSchetselaar, E M; Bellefleur, G; Craven, J A; Ansari, S M; Enkin, R J
SourceTargeted Geoscience Initiative: 2017 report of activities, volume 1; by Rogers, N (ed.); Geological Survey of Canada, Open File 8358, 2018 p. 229-242, (Open Access)
PublisherNatural Resources Canada
Documentopen file
Mediaon-line; digital
RelatedThis publication is contained in Rogers, N; (2018). Targeted Geoscience Initiative: 2017 report of activities, volume 1, Geological Survey of Canada, Open File 8358
File formatpdf
AreaSnow Lake
Lat/Long WENS-100.2000 -100.1000 54.9000 54.8500
Subjectseconomic geology; geochemistry; geophysics; structural geology; igneous and metamorphic petrology; mineral deposits; mineral exploration; mineral potential; modelling; ore controls; ore mineral genesis; mineralization; base metals; volcanogenic deposits; sulphide deposits; zinc; hydrothermal systems; hydrothermal alteration; fluid flow; fluid dynamics; lithogeochemistry; geophysical surveys; seismic interpretations; seismic waves; p waves; seismic reflection surveys; petrophysics; magnetotelluric interpretations; conductivity; electromagnetic fields; whole rock geochemistry; statistical analyses; regression analyses; drill core analyses; bedrock geology; lithology; igneous rocks; intrusive rocks; mafic intrusive rocks; gabbros; diorites; granodiorites; tonalites; granites; ultramafic rocks; volcanic rocks; volcaniclastics; tuffs; rhyolites; dacites; lava flows; breccias; basalts; andesites; rhyodacites; structural features; faults; faults, thrust; Archean; Canadian Shiield; Trans-Hudson Orogeny; Chisel Basin; Lalor VMS deposit; Sask Craton; Chisel- Lalor structural contact; ore systems approach; volcanogenic massive sulphide (VMS) deposits; 3D modelling; Paleoproterozoic; physical rock properties; Carbonate-Chorite-Pyrite (= CCPI) index; Precambrian; Proterozoic
Illustrationsgeoscientific sketch maps; plots; 3-D images; tables; 3-D models; models; cross-sections; graphs
ProgramTargeted Geoscience Initiative (TGI-5), Knowledge Management Coordination
ProgramTargeted Geoscience Initiative (TGI-5), Volcanic and sedimentary systems
Released2018 01 19
AbstractThis research activity aims a developing a better understanding of the geophysical response of hydrothermally-altered rocks associated with volcanogenic massive sulphide (VMS) deposits. Integrated modelling of physical rock property, whole rock geochemistry and 3D seismic data from the Lalor VMS deposit, Snow Lake, Manitoba enhanced insight into the seismic responses of hydrothermally-altered rocks in the footwall of the massive sulphide ore zone. Multivariate regression of P-wave velocity and density on lithogeochemical proxies for protolith composition, mineralization and hydrothermal alteration suggests that hydrothermal alteration in the footwall of the Lalor deposit enhanced acoustic impedance contrast between mafic to felsic volcanic units. Compositional variations between mafic, intermediate and felsic volcanic rocks, as modelled by the log(Zr/TiO2) immobile element ratio, remains the predominant factor that controls seismic response, independent from the intensity of hydrothermal alteration. The results obtained from the multivariate regression model are further corroborated by seismic forward modelling experiments, yielding enhanced seismic reflectivity in the intensely-altered footwall when alteration proxies are included in the 3D seismic rock property models. In parallel, geophysical response modelling of magnetotelluric (MT) data will be developed based on forward and inverse modelling routines on tetrahedral meshes, which yield results that are compatible with the general geological structure of the deposit. Initial unconstrained 3D MT inversions show a conductive zone between 600 to 800 m depth corresponding to the Lalor deposit, as well as, a highly conductive zone between depths of 500 to 1500 m, about 0.5 to 1.2 km to the southwest of the deposit.