| Titre | Evidence for ~40 MA transition from a forearc to a foreland basin in eastern part of Labrador Trough |
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| Auteur | Henrique-Pinto, R; Guilmette, C; McNicoll, V; Bilodeau, C; Corrigan, D |
| Source | GSA Annual Meeting in Denver, Colorado, USA - 2016; Geological Society of America, Abstracts With Programs vol. 48, no. 7, 204-6, 2016 p. 1, https://doi.org/10.1130/abs/2016AM-285515 |
| Année | 2016 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20190408 |
| Éditeur | Geological Society of America |
| Réunion | GSA annual meeting; Denver, CO; US; Septembre 25-28, 2016 |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1130/abs/2016AM-285515 |
| Media | en ligne; numérique |
| Formats | html |
| Province | Québec; Terre-Neuve-et-Labrador |
| Région | Labrador |
| Sujets | géochronologie; Sciences et technologie; Nature et environnement |
| Programme | GEM2 : La géocartographie de l'énergie et des minéraux Zone centrale de la région d'Hudson/Ungava |
| Diffusé | 2016 09 01 |
| Résumé | (disponible en anglais seulement)
The New Quebec Orogen (NQO) is a Paleo-Proterozoic supra-crustal belt that underwent reworking when the Superior Craton collided with the Core Zone, during the
Trans-Hudson Orogeny. Within the NQO, the Labrador Trough regroups greenschist-facies sedimentary and volcanic sequences (Kaniapiskau Supergroup) inferred to represent the rifted margin of the Superior and a potential oceanic domain, whereas the
Laporte Group, composed of similar successions but metamorphosed to higher grades, remains of unclear origin. Competing models purport that the Laporte Group is either a deeper, higher grade exposure of the Labrador Trough, or an exotic terrane.
Large scale sampling, petrography and U-Pb detrital zircon geochronology provide insights to elucidate the sedimentary provenance and depositional environments for both zones.
New results reveal a different sedimentary architecture for both units.
In particular, the majority of metarenites from Kaniapiskau Supergroup have medium to high textural and compositional maturity, such as meta-quartzarenites and meta-subarkoses; whereas the metarenites from Laporte Group suggest photoliths with low to
medium textural/compositional maturity, like feldspathic and some lithic meta-wackes.
A total of 343 zircon analyses from the Kaniapiskau Supergroup yield ages older than 2.5 Ga (2565 ±12 Ma, youngest zircon), with typical Archean Superior-type
signature as the main source area and a main statistical age peak at 2722 Ma. There is more than a 150 Ma gap between detrital zircon ages and the interpreted depositional age, suggesting a divergent environment like a rifted and/or passive
margin.
In contrast, detrital zircons from the Laporte Group (a total of 234 analyses) yield ages older than 1.8 Ga, with the youngest zircon dated at 1827 ± 25 Ma and a dominant statistical age peak at 1843 Ma. Metamorphic monazite ages from
Laporte Group previously dated at 1793 ± 2 Ma suggest a relative short depositional time period (around 40 Ma). The presence of detrital zircon age peaks at 2.2- 2.4 Ga suggests an exotic terrain compatible with the Core Zone as the main source area.
The presence of the orogenic-type De Pas Batholith suggests eastward subduction at 1840-1830 Ma and the time period between detrital ages and deposition may represent a transition between forearc to foreland basin. |
| GEOSCAN ID | 321683 |
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