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TitleOn Archean craton growth and stabilisation: insights from lithospheric resistivity structure of the Superior Province
AuthorHill, G J; Roots, E A; Frieman, B M; Haugaard, R; Craven, J A; Smith, R S; Snyder, D BORCID logo; Zhou, X; Sherlock, R
SourceEarth and Planetary Science Letters vol. 562, 116853, 2021 p. 1-10, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20200741
PublisherElsevier Publications
Mediapaper; on-line; digital
File formatpdf; html
NTS41O/14; 41O/15; 41O/16; 42B/01; 42B/02; 42B/03; 42B/06; 42B/07; 42B/08; 42B/09; 42B/10; 42B/11
Lat/Long WENS -83.5000 -82.0000 48.7500 47.7500
Subjectstectonics; structural geology; geophysics; Science and Technology; Nature and Environment; Archean; crustal studies; crustal structure; crustal thickness; crustal shortening; craton; lithosphere; continental crust; geophysical surveys; magnetotelluric surveys; resistivity; anomalies; models; tectonic evolution; orogenesis; magmatism; hydrothermal systems; fluid flow; deformation; structural controls; bedrock geology; structural features; faults; shear zones; thermal analyses; Superior Province; Superior Craton; Swayze Greenstone Belt; Kapuskasing Structural Zone; Porcupine-Destor Fault; Ivanhoe Lake Fault; Rundle Fault; Ridout Fault; Precambrian
Illustrationslocation maps; geoscientific sketch maps; geophysical profiles; schematic cross-sections
ProgramOpen Geoscience
Released2021 03 04
AbstractThe nature of lithospheric evolution and style of the driving tectonic processes during the growth and stabilisation of continental crust in the Archean remain enigmatic. The hotter, rheologically weak Archean crust would be unable to support thick orogens. Thus, gravitational collapse likely occurred when continental fragments became overthickened and/or when far-field stresses were relieved during the terminal stages of orogenesis. 3D magnetotelluric resistivity models of the Archean Superior Province, reveal the presence of low resistivity zones in the mid-lower crust that reflect a protracted history of magmatic-hydrothermal activity contemporaneous with construction and collapse. These include sub-vertical zones of low resistivity in the mid-upper crust, inferred to represent corridors of paleo-fluid flow along crustal-scale structural networks developed in response to terrane amalgamations. Subsequent orogenic collapse resulted in widespread lateral flow within the lower crust accommodated by sub-horizontal shear zones and included magmatic refertilisation. Thus, the preserved low-resistivity anomalies in the mid-lower crust represent an amalgamation of magmatic-hydrothermal and deformational processes that occurred during construction, peak orogenesis, and collapse in the Archean.
Summary(Plain Language Summary, not published)
This paper provides a new image of the subsurface beneath a greenstone belt in northern Ontario that offers never before seen insights into the formation of Canada's most valuable ore systems, and helps answer the question why certain areas of Ontario and Quebec are better endowed than others. This study answers fundamental questions about the role conduits play in the development of metal deposits in the Canadian Shield. Conduits along which ore fluids are thought to ascend from mantle depths are believed to be an important component of ore system development, but clear images of these conduits in Canada are rare. This paper uses 3-d model techniques applied to new and legacy geophysical data to demonstrate that conduits are related to major tectonic deformational zones associated with known mineral deposits, and to show that the conduits may originate in a large electrically conductive zone at mid-crustal depths. The conductive zone is interpreted as relicts of ancient ascending mineralizing fluids that escaped from a magmatic event originating in the Earth's mantle and deposited as thick films within the crust. This event may be the source of some of the most valuable ore forming fluids in Canada.

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