| Title | Conditions and timing of low-pressure - high-temperature metamorphism in the Montresor Belt, Rae Province, Nunavut |
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| Author | Dziawa, C; Gaidies, F; Percival, J |
| Source | Canadian Journal of Earth Sciences vol. 56, no. 6, 2018 p. 654-671, https://doi.org/10.1139/cjes-2018-0184  Open Access |
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| Year | 2018 |
| Alt Series | Natural Resources Canada, Contribution Series 20190125 |
| Publisher | Canadian Science Publishing |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf (Adobe® Reader®); html |
| Province | Nunavut |
| NTS | 66I/03; 66I/04 |
| Area | Meadowbank River |
| Lat/Long WENS | -97.5833 -97.2500 66.1667 66.0000 |
| Subjects | tectonics; igneous and metamorphic petrology; geochronology; geochemistry; tectonic history; metamorphism; foliation; gneissosity; faulting; intrusions; diabase dykes; fluid migration; crustal
evolution; crustal thickness; pressure-temperature conditions; phase equilibria; modelling; radiometric dating; mineral assemblages; crystallization; whole rock geochemistry; bedrock geology; structural features; folds; synforms; shear zones; faults;
faults, thrust; faults, extension; fault zones; electron probe analyses; petrographic analyses; garnet; alteration; andalusite; mica; Rae Province; Rae Domain; Montresor Belt; Montresor Group; Trans-Hudson Orogeny; Snowbird Tectonic Zone;
Chesterfield Fault Zone; Chantrey Mylonite Zone; Paleoproterozoic; Precambrian; Proterozoic |
| Illustrations | location maps; geological sketch maps; tables; photomicrographs; 3-D images; gravity profiles; bar graphs; plots; ternary diagrams; profiles; phase diagrams |
| Program | GEM2: Geo-mapping for Energy and Minerals Rae Province, Chantrey-Thelon |
| Released | 2018 12 03 |
| Abstract | Pressure-temperature-time (P-T-t) estimates for the Montresor Belt, obtained using phase equilibria and geospeedometry modelling integrated with in situ U-Th-Pb monazite geochronology, shed new light on
the tectonometamorphic effects of the Snowbird phase of the Trans-Hudson orogeny. Typical metapelitic assemblages of the lower Montresor group consist of white mica, biotite, plagioclase, quartz, and andalusite, which in some rocks is partly or
completely pseudomorphed by white mica. The observed assemblages reflect peak P-T conditions centring at approximately 575 °C and 3 kbar. Rocks with high bulk Fe/Mg contents contain compositionally zoned garnet, permitting the addition of further
constraints on the conditions of metamorphism in the Montresor Belt: Core compositions of earliest-grown garnets indicate initial garnet crystallization at approximately 535 °C and 2.3 kbar, suggesting a nearly isobaric P-T path of prograde
metamorphism with a gradient of approximately 50 °C/kbar. Chemical age-dating of monazite inclusions in garnet yields ages of ca. 1870 ± 9 to 1837 ± 9 Ma. Retrograde, pseudomorphic andalusite replacement by white mica at approximately 540 °C is
inferred to have been controlled by variations in bulk rock chemistry. Morphologically corroded and chemically heterogeneous monazite adjacent to white mica pseudomorphs suggests that andalusite replacement took place at ca. 1792 ± 10 Ma, possibly
associated with extension and movement along the detachment fault separating the upper and lower Montresor groups. Simulations of diffusion across chlorite- and biotite-filled cracks in garnet assumed to be coeval with andalusite replacement suggest
that the rocks have experienced the retrograde event for at least 20 My. |
| GEOSCAN ID | 314806 |
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