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TitleBottom-up mineral exploration: ore-element upgrading in the upper mantle and tools for its discovery
LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorLawley, C J MORCID logo; Kjarsgaard, B AORCID logo
SourceTargeted Geoscience Initiative 5: contributions to the understanding of Canadian gold systems; by Mercier-Langevin, P (ed.); Lawley, C J MORCID logo (ed.); Castonguay, SORCID logo (ed.); Geological Survey of Canada, Open File 8712, 2020 p. 157-164, Open Access logo Open Access
PublisherNatural Resources Canada
Documentopen file
Mediaon-line; digital
RelatedThis publication is contained in Targeted Geoscience Initiative 5: contributions to the understanding of Canadian gold systems
File formatpdf
ProvinceBritish Columbia; Ontario; Nunavut
NTS32D/04; 32D/05; 76E; 104N
AreaAtlin; Kirkland Lake; Contwoyto Lake
Lat/Long WENS-134.0000 -132.0000 60.0000 59.0000
Lat/Long WENS -79.7500 -79.7500 48.4833 48.1167
Lat/Long WENS-112.0000 -110.0000 66.0000 65.0000
Subjectseconomic geology; tectonics; igneous and metamorphic petrology; geochemistry; geophysics; Science and Technology; Nature and Environment; mineral deposits; gold; diamond; mineral exploration; exploration methods; ore mineral genesis; mineralization; ore controls; mantle; crustal studies; tectonic setting; lithosphere; oceanic crust; ophiolites; continental crust; craton; subduction zones; downgoing slab; source areas; bedrock geology; lithology; igneous rocks; intrusive rocks; kimberlites; peridotites; harzburgites; pyroxenites; lherzolites; transport mechanisms; sulphides; base metals; precipitation; fluid inclusions; metasomatism; mineral enrichment; geochemical analyses; whole rock geochemistry; trace element geochemistry; isotopic studies; mass spectrometer analysis; geophysical surveys; geophysical interpretations; electron microscope analyses; Canadian Cordillera; Nahlin Ophiolite; Canadian Shield; Superior Craton; Slave Craton; Data processing; Phanerozoic; Precambrian
Illustrationslocation maps; schematic cross-sections; photomicrographs; geochemical plots
ProgramTargeted Geoscience Initiative (TGI-5) Gold ore systems
Released2020 06 11; 2023 03 17
AbstractMineral exploration targeting typically focuses on the critical pathways and depositional traps of ore systems. The role of pre-enriched source regions on ore deposit genesis is unclear, particularly for systems that involve significant transport of ore components (e.g. Au). Because Au is suggested to be derived from the mid- to lower-crust and/or upper mantle at orogenic deposits, it is not surprising that the deepest and most inaccessible parts of this ore system is also the least studied and understood. Herein we address that knowledge gap by studying the upper mantle directly, using examples of young ophiolitic mantle (Atlin, British Columbia) and ancient cratonic mantle (Superior craton, Ontario; Slave craton, Nunavut). Project results demonstrate two dominant mechanisms for Au upgrading in the lithospheric mantle: (1) base metal sulphide precipitated during melt:rock reactions between peridotitic residues and asthenospheric melts, and (2) hydrous, fluid-inclusions trapped after release from subducting slabs. The remelting of such pre-enriched metasomatized mantle has been previously proposed as a viable source for a variety of ore systems (e.g. mafic to ultramafic rock-hosted platinum-group element deposits). Mapping the architecture of these deep lithospheric metasomatized mantle domains and their association with rising asthenospheric melts is of significant interest for mineral exploration. New geochemical methods and data processing completed as part of the current study, coupled with advances in geophysical imaging, provide additional tools for mapping these pre-enriched lithospheric mantle domains at depth.
Summary(Plain Language Summary, not published)
The main objective of phase 5 (2015-2020) of Natural Resources Canada and Geological Survey of Canada's Targeted Geoscientific Initiative (TGI) program was to generate new knowledge, methodologies and models to enhance the exploration industry's ability to detect buried ore deposits. This synthesis volume contains 20 individual papers that discuss craton to deposit-scale characteristics of auriferous deposits, plus some support material pertaining to the TGI-5 Gold project.

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