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Title3D magnetic inversion of mineral prospects in the Great Bear Magmatic Zone, Northwest Territories
AuthorHayward, N
SourceGeological Survey of Canada, Open File 7421, 2013, 43 pages, (Open Access)
PublisherNatural Resources Canada
Documentopen file
Mediaon-line; digital
File formatreadme
File formatpdf; UBC; rtf
ProvinceNorthwest Territories
NTS85N/09; 85N/10; 85N/11; 85N/12; 85N/13; 85N/14; 85N/15; 85N/16; 86C; 86F; 86K
AreaGameti; Great Bear Lake
Lat/Long WENS-118.4000 -116.2000 66.7000 63.5000
Subjectseconomic geology; geophysics; geophysical surveys; geophysical interpretations; aeromagnetic surveys; aeromagnetic interpretation; magnetic interpretations; magnetic anomalies; magnetic surveys; mineral occurrences; iron oxides; copper; gold; mineralization; alteration; magnetite; hematite; models; magnetic modelling; Great Bear Magmatic Zone; NICO deposit; Sue-Dianne deposit; Precambrian; Proterozoic
Illustrationslocation maps; profiles
ProgramGEM: Geo-mapping for Energy and Minerals, Iron-oxide Copper-gold (IOCG) / Multiple Metals - Great Bear Lake (NWT)
Released2013 06 26
AbstractThe Great Bear magmatic zone is a Paleoproterozoic continental magmatic arc in the Northwest Territories, Canada. Interpretation of aeromagnetic data shows the region to be associated with high-amplitude magnetic anomalies which are related to zones of iron oxide-alkali-altered rocks and polymetallic iron oxide-copper-gold deposits and prospects.
Iron oxide-alkali-altered rocks in the field may be obscured by surficial cover and lakes, and surface exposures may not be representative of the extent and intensity of alteration. Therefore geophysical techniques are employed to investigate regional prospects across the variably exposed and inaccessible terrain. Three-dimensional magnetic inversion models are constructed for twelve of the prospects and deposits in order to investigate the scale, geometry and magnetic susceptibility of their highly magnetite-altered zones. The choice of model locations was guided by known mineral prospects, targets resulting from prior two-dimensional geophysical methods, and the extent of the associated magnetic anomalies.
Summary(Plain Language Summary, not published)
The three-dimensional scale and intensity of magnetism associated with iron oxide alkali alteration and potential iron oxide-copper-gold and affiliated mineralised zones is estimated for prospective areas of the Great Bear magmatic zone. This zone exposes parts of a 1.87 billion year old volcanic mountain range similar to the South American Andes. During evolution, hot volcanic fluids moved through the rocks, transforming their minerals through chemical reactions. Among the new minerals is magnetite, a highly magnetic mineral associated with iron oxide-copper-gold and affiliated mineralisation. The regional variation in magnetic field intensity, mapped by airborne surveys, is related to the amount of magnetic minerals in the rocks. Three-dimensional models of the magnetic data are developed for twelve areas with high multiple-metal, mineral potential. The models estimate the scale and intensity of the magnetite alteration as a vector to mineralization often not exposed at surface.