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TitleMagmatic, hydrothermal and ore element transfer processes of the southeastern Archean Superior Province implied from electrical resistivity structure
AuthorRoots, E A; Hill, G J; Frieman, B M; Wannamaker, P E; Maris, V; Calvert, A J; Craven, J A; Smith, R S; Snyder, D BORCID logo
SourceGondwana Research vol. 105, 2022 p. 84-95, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20210262
Mediapaper; on-line; digital
File formatpdf; html
ProvinceOntario; Quebec
NTS31M/09; 31M/10; 31M/11; 31M/12; 31M/13; 31M/14; 31M/15; 31M/16; 31N/12; 31N/13; 32C/04; 32C/05; 32C/12; 32C/13; 32D; 32E/01; 32E/02; 32E/03; 32E/04; 32F/04; 41P/09; 41P/10; 41P/15; 41P/16; 42A/01; 42A/02; 42A/07; 42A/08; 42A/09; 42A/10; 42A/15; 42A/16; 42H/01; 42H/02
AreaLarder Lake; Abitibi; Pontiac
Lat/Long WENS -81.0000 -77.5000 49.2500 47.5000
Subjectseconomic geology; tectonics; structural geology; geophysics; Science and Technology; Nature and Environment; Archean; mineral deposits; metals; gold; ore mineral genesis; ore controls; structural controls; mineralization; crustal structure; tectonic setting; orogenies; magmatism; intrusions; plutons; metamorphism; deformation; hydrothermal systems; greenstone belts; fluid dynamics; fluid flow; flow systems; metallogeny; geophysical surveys; seismic reflection surveys; magnetotelluric surveys; electrical resistivity; modelling; crustal models; bedrock geology; structural features; faults; graphite; sulphides; Superior Province; Abitibi Subprovince; Precambrian
Illustrationslocation maps; geoscientific sketch maps; geophysical profiles; schematic representations
ProgramOpen Geoscience
Released2022 01 04
AbstractAlthough magmatic- and metamorphic- derived fluids are widely recognized mineralizing agents, the role of crustal architecture in defining source and sink zones within the middle to lower crust and upper mantle of ancient orogens remains enigmatic. The globally largest and best-preserved Archean greenstone belts lie in the Superior Province, Canada. They provide an ideal location to investigate the influence of igneous construction and subsequent syn-deformational plutonism and metamorphism on the localization of metal-rich melts and fluids throughout the crustal column. Integration of three-dimensional magnetotelluric modelling and seismic reflection sections across the Abitibi subprovince reveals details of a 'whole-of-crust' magmatic and hydrothermal system. East-west low resistivity structures broadly underlie the surface traces of the major deformation zones that are host to significant gold endowment (>200 Moz), while mid-crustal cross trends suggest mineralized fluids flowed along 'pipes' within fault planes. Most low resistivity structures are inferred to represent domains containing interconnected zones of graphite and/or sulfide. These delineate relict mantle source/transit domains and crustal pathways enriched by the flow of magmas or metamorphic fluids genetically related to a late-stage pulse of ore-bearing magmatism, possibly as a result of slab break-off or delamination. Using the combined MT and seismic data, we develop a 3-D crustal-scale model which highlights how evolving orogenic architecture-controlled mass transfer and metallogenic processes developed.
Summary(Plain Language Summary, not published)
New critical metal deposits are proving difficult to locate as most near surface mineralized systems have been found. Magnetotelluric data were collected to provide deep images of conductive features in the crust and upper mantle below a large mineralized system to determine if crustal architecture played a role in determining favorable locations for metals to be deposited . The images revealed 'pipes' along which ancient ore forming fluids flowed and that were a primary source of much of the metals in the Abitibi region.

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