| Title | Magnetic and gravity models, northern half of the Taltson Magmatic Zone, Rae Craton, Northwest Territories: insights into upper crustal structure |
| Download | Downloads |
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| Licence | Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences. |
| Author | Thomas, M D |
| Source | Geological Survey of Canada, Current Research (Online) 2022-1, 2022, 22 pages, https://doi.org/10.4095/328244  Open Access |
| Image |  |
| Year | 2022 |
| Publisher | Natural Resources Canada |
| Document | serial |
| Lang. | English |
| Media | on-line; digital |
| File format | pdf |
| Province | Northwest Territories |
| NTS | 75C/04; 75C/05; 74D; 75E; 75L/01; 75L/02; 85A/08; 85A/09; 85A/16; 85H/01; 85H/02; 85H/07; 85H/08 |
| Area | Pilot Lake; Rutledge Lake; Taltson Lake; Tsu Lake; Thubun Lake; Hill Island Lake; Thekulthili lake |
| Lat/Long WENS | -113.0000 -109.5000 62.5000 60.0000 |
| Subjects | regional geology; structural geology; geophysics; Science and Technology; Nature and Environment; geophysical surveys; geophysical interpretations; gravity surveys; magnetic surveys; magnetic
susceptibility; magnetic field; modelling; gravity models; bouguer gravity; bouguer anomalies; magnetic modelling; bedrock geology; lithology; igneous rocks; granitic rocks; intrusive rocks; granodiorites; granites; metamorphic rocks; gneisses;
crustal structure; geometric analyses; structural trends; shear zones; intrusions; Archean; Taltson Magmatic Zone; Rae Craton; Palaeoproterozoic; Neoarchean; Slave Granite; Konth Granite; Precambrian; Proterozoic |
| Illustrations | geoscientific sketch maps; gravity profiles; magnetic profiles; cross-sections; 3-D models |
| Program | GEM2: Geo-mapping for Energy and Minerals Rae Province Project Management |
| Released | 2022 04 07 |
| Abstract | A prominent magnetic low along an eastern portion of the Paleoproterozoic Taltson magmatic zone (TMZ) correlates mainly with the youngest granitoid in the zone, the peraluminous ca. 1936 Ma Konth
granite. Flanking belts of higher magnetic intensity coincide mainly with slightly older Taltson plutonic rocks (e.g. ca. 1986 Ma Deskenatlata granodiorite, ca. 1955 Ma Slave granite) to the west and Neoarchean and/or Paleoproterozic gneisses of the
Rae Craton to the east. A prominent gravity low along a portion of the northeastern margin of the TMZ correlates mainly with the Konth granite. Modelling of east-west magnetic and gravity profiles crossing the TMZ is used to investigate the
geometrical and geological significance of these signatures.
Modelling of the gravity low revealed a basin-like shape, with a maximum thickness of 14.9 km, for a composite unit of Konth-Slave magmatic suites. Magnetic modelling, the preferred
technique north and south of the gravity minimum, yielded basin-like shapes for an essentially nonmagnetic Konth-Slave unit, but with much smaller maximum thicknesses of 5.0 and 6.5 km, respectively. Farther south in the TMZ, strongly magnetic units
within mapped Konth and Slave granites preclude definition of a nonmagnetic Konth-Slave unit. Aside from the Slave unit, most other modelled magnetic units are generally steep and narrow and have fairly large magnetic susceptibilities. They are
modelled to a depth of 6.2 km below sea level and have a steeply dipping, near-surface structural fabric extending to significant depth. Granitoids in the TMZ have previously been designated as ilmenite series or magnetite series, but modelled
susceptibilities indicate that revisions to some designations may be required. |
| Summary | (Plain Language Summary, not published)
A prominent Precambrian belt of granitic rocks, the Taltson Magmatic Zone (TMZ), extends southward from the East Arm of Great Slave Lake along the
western margin of the Precambrian Shield. It is geologically mapped in some detail, but little is known about the nature of the zone at depth. Magnetic and gravity data sets for the region outline distinct signatures that have been modelled
quantitatively to define crustal units having different magnetizations and densities that provide a proxy for geological units. Modelling of a strong negative gravity signature (gravity low) in the northeastern part of the TMZ outlines a basin-like
shape, maximum thickness 14.9 km, for a composite unit of the two principal granites, the Konth and Slave granites. Modelling of a prominent magnetic low covering much of the eastern half of the TMZ likewise determined basin-like shapes for an
essentially non-magnetic Konth-Slave unit. Most other modelled magnetic units within granitic rocks or within gneissic rocks bordering the TMZ are generally steep, narrow and quite magnetic. They descend to a depth of 6.2 km below sea level,
indicating steeply dipping near-surface structural fabric. |
| GEOSCAN ID | 328244 |
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