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TitleMagnetic and gravity characteristics of the Thelon and Taltson orogens, northern Canada: tectonic implications
LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorThomas, M D
SourceGeological Survey of Canada, Bulletin 618, 2022, 33 pages, Open Access logo Open Access
PublisherNatural Resources Canada
Mediadigital; on-line
File formatpdf
ProvinceNorthwest Territories; Nunavut; Alberta; Saskatchewan; Manitoba
NTS64N; 64O; 65B; 65C; 65D; 65E; 65F; 65G; 65J; 65K; 65L; 65M; 65N; 65O; 66B; 66C; 66D; 66E; 66F; 66G; 66J; 66K; 66L; 66M; 66N; 66O; 74M; 74N; 74O; 74P; 75; 76; 84O; 84P; 85A; 85B; 85G; 85H; 85I; 85J; 85O; 85P; 86A; 86B; 86G; 86H; 86I; 86J; 86O; 86P
AreaCoronation Gulf; Queen Maud Gulf; Great Slave Lake; Lake Athabasca
Lat/Long WENS-114.5000 -99.0000 68.0000 59.0000
Subjectsgeophysics; tectonics; geochemistry; Science and Technology; Nature and Environment; Archean; geophysical surveys; magnetic surveys; total field magnetics; gravity surveys; anomalies; bouguer anomalies; tectonic interpretations; tectonic elements; tectonic models; tectonic evolution; plate margins; rifting; subduction; magmatism; intrusions; faulting; displacement; orogenies; trace element geochemistry; bedrock geology; structural features; nappes; faults; shear zones; lithology; granitic rocks; sedimentary basins; Canadian Shield; Thelon Tectonic Zone; Taltson Magmatic Zone; Great Slave Lake Shear Zone; Slave Craton; Rae Craton; Buffalo Head Terrane; Kilohigok Basin; East Arm Basin; McDonald Fault; Precambrian; Proterozoic
Illustrationsgeoscientific sketch maps; schematic cross-sections; schematic representations
ProgramGEM2: Geo-mapping for Energy and Minerals Rae Province Project Management
Released2022 08 11
AbstractDifferences of opinion concerning the relationship between the Thelon tectonic zone and the Taltson magmatic zone, as to whether they are individual tectonic elements or two independent elements, have generated various plate tectonic models explaining their creation. Magnetic and gravity signatures indicate that they are separate entities and that the Thelon tectonic zone and the Great Slave Lake shear zone form a single element. Adopting the single-element concept and available age dates, a temporally evolving plate tectonic model of Slave-Rae interaction is presented. At 2350 Ma, an Archean supercontinent rifted along the eastern and southern margins of the Slave Craton. Subsequent ocean closure, apparently diachronous, began with subduction at 2070 Ma in the northern Thelon tectonic zone, followed by subduction under the Great Slave Lake shear zone at 2051 Ma. Subduction related to closure of an ocean between the Buffalo Head terrane and the Rae Craton initiated under the Taltson magmatic zone at 1986 Ma, at which time subduction continued along the Thelon tectonic zone. At 1970 Ma, collision in the northern Thelon tectonic zone is evidenced in the Kilohigok Basin. From 1957 to 1920 Ma, plutonism was active in the Taltson magmatic zone, Great Slave Lake shear zone, and southern Thelon tectonic zone. The plutonism terminated in the northern Thelon tectonic zone at 1950 Ma, but it resumed at 1910 Ma and continued until 1880 Ma. The East Arm Basin witnessed igneous activity as early as 2046 Ma, though this took place more continuously from 1928 to 1861 Ma; some igneous rocks bear subduction-related trace element signatures. These signatures, and the presence of northwest-verging nappes, may signify collision with the Great Slave Lake shear zone as a result of southeastward subduction, completing closure between the Slave and Rae cratons.
Summary(Plain Language Summary, not published)
The Thelon tectonic zone (TTZ) and Taltson magmatic zone (TMZ) are two prominent belts of Proterozoic rocks along the margin of the Rae craton in the northwestern Canadian Shield, offset from one another along the McDonald fault. Opinions differ on whether they were once a single mega-structure that evolved together, or two separate structures evolving independently. Both structures are associated with strong magnetic and gravity signatures, evaluation of which indicates that they are independent structures. Magnetic signatures indicate also that the Great Slave Lake shear zone (GSLSZ), partially flanked by the McDonald fault, represents a southwestward extension of the TTZ that truncates the northern end of the TMZ. The conclusions of the geophysical analysis are examined in the context of available age dates and a chronological plate tectonic model is presented. It includes rifting of an Archean supercontinent to produce the Rae and Slave cratons, and the subsequent closure of an intervening ocean and continental collision that developed the TTZ, TMZ and GSLSZ.

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