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TitleShallow crustal structure in the Meadowbank River - Tehek Lake area: insights from gravity and magnetic modelling
AuthorThomas, M D
SourceGeological Survey of Canada, Open File 7308, 2012, 42 pages, (Open Access)
PublisherNatural Resources Canada
Documentopen file
Mediaon-line; digital
File formatpdf
NTS56D/10; 56D/11; 56D/12; 56D/13; 56D/14; 56D/15; 56E/02; 56E/03; 56E/04; 56E/05; 56E/06; 56E/07; 56E/10; 56E/11; 56E/12; 66A/09; 66A/10; 66A/11; 66A/14; 66A/15; 66A/16; 66H/01; 66H/02; 66H/03; 66H/06; 66H/07; 66H/08; 66H/09; 66H/10; 66H/11
AreaMeadowbank River; Tehek Lake; Piperdream Lake
Lat/Long WENS-97.5000 -94.5000 65.7500 64.5000
Subjectsigneous and metamorphic petrology; structural geology; geophysics; magnetic interpretations; magnetic surveys; magnetic anomalies; magnetic modelling; gravity surveys; gravity models; gravity interpretations; gravity anomalies; geophysical interpretations; geophysical surveys; modelling; rock density analyses; faults; folds; structural features; metamorphic rocks; gneisses; metamorphism; Archean; iron formations; gravity profiles; gold; mineral deposits; bedrock geology; Meadowbank deposits; Precambrian
Illustrationscross-sections; location maps; profiles
ProgramGEM: Geo-mapping for Energy and Minerals, Uranium
Released2012 12 14
AbstractRelatively closely-spaced gravity data measured along two traverses near the Meadowbank gold deposits near Tehek Lake have been modelled in concert with regional magnetic data to provide a preliminary of upper crustal structure and rock types. Modelling has also been completed along two regional gravity profiles, indicating that Archean supracrustal rocks attain thicknesses ranging from 2.8 km to 8.3 km in fairly localised keels, but are generally 1000 rn to 2000 n1 thick over large sections of crust. Parts of thinner sections of supracrustal rocks are modelled to be overlain by very thin (<400 m thick) sheets of Archean granitic rocks that may be in intrusive or tectonic contact. Regional modelling also suggests the presence of thin (~3 km thick), buried sheet-like Proterozoic granitic bodies. Modelling along the detailed gravity traverses yields similar thicknesses of supracrustal rocks, generally between 500 m and 1700 m thick, which are also overlain by thin sheets of Archean granitic rocks. Modelled contacts between supracrustal units are typically very steep. A notable product of magnetic modelling is a large volume of high 1nagnetic susceptibility iron formation distributed in many narrow, steep units extending from the surface or near-surface to depths ranging from about 1000 m to 1200 m. These depths probably represent minimum depths because of limitations in modelling steep, narrow bodies. Another revelation of modelling is the large volumes of komatiite predicted as extensions of relatively small units of komatiite mapped at surface. Granitic bodies of possible Proterozoic age have been modelled in the upper crust. One extends vertically over about 4800 1n, whereas others ex tend no deeper than 1400 m below surface.