| Titre | U-Th-Pb geochronology and Lu-Hf isotope geochemistry of detrital zircons in metasedimentary rocks of the southern coast mountains batholith |
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| Auteur | Dafov, M N; Carrera, A; Gehrels, G E; Alberts, D; Pereira, M; Robinson Cecil, M; Rusmore, M E; Stowell, H H; Woodsworth, G J |
| Source | Lithosphere issue 1, 8854686, 2020 p. 1-21, https://doi.org/10.2113/2020/8854686  Accès ouvert |
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| Année | 2020 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20200732 |
| Éditeur | Geoscienceworld |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.2113/2020/8854686 |
| Media | papier; en ligne; numérique |
| Formats | pdf; html |
| Province | Colombie-Britannique |
| Lat/Long OENS | -137.9156 -121.9500 58.0700 47.0000 |
| Sujets | isotopes; zircon; textures; géochronologie; Sciences et technologie; minéraux métalliques; tectonique |
| Illustrations | cartes de localisation; photographies; graphiques; diagrammes; représentations graphiques combinées |
| Diffusé | 2020 09 14 |
| Résumé | (disponible en anglais seulement)
Most metasedimentary rocks in the southern Coast Mountains batholith are of uncertain tectonic affinity because they occur in discontinuous pendants surrounded
by large intrusive bodies, and many protolith features are obscured by regional deformation and metamorphism. This study uses U-Th-Pb ages and Lu-Hf isotope signatures of detrital zircons in metasedimentary rocks in Bute, Loughborough, and Knight
Inlets in an effort to test possible correlations with the adjacent Wrangellia, Alexander, Taku, Yukon-Tanana, and Stikine terranes. Detrital zircons from metasedimentary samples yield ages that belong to age groups of 590-528 Ma (peak age of 560
Ma), 485-432 Ma (peak age of 452 Ma), 356-286 Ma (peak age of 307 Ma), and 228-185 Ma (peak ages of 215 and 198 Ma). A small number of ~1.1-1.9 Ga grains are also present. eHft values of the 590-185 Ma grains yield a progression from intermediate (0
to +5) values to more juvenile (mostly +4 to +15) values from Neoproterozoic through early Mesozoic time. The Comparison of these results with similar data sets from adjacent terranes demonstrates that primary connections with the Yukon-Tanana and
Taku terranes are unlikely but are consistent with primary connections with the Wrangellia, Stikine, and/or Alexander terranes. Unfortunately, the available constraints are not sufficient to eliminate any of these options or the possibility that the
pendants are a unique tectonic fragment. Zircons from the metasedimentary samples also yield U-Th-Pb ages of 165-128 Ma (peak age of 152 Ma) and 114-88 Ma (peak age of 102 Ma). eHft values of these zircon domains are mostly juvenile (+7 to +13).
Comparison of U concentrations, U/Th values, and CL textures of zircons from the metasedimentary samples, leucocratic sills that intrude the pendants, and surrounding plutonic bodies suggests that most of the young grains, as well as widespread
younger rims on older grains, grew during metamorphism associated with emplacement of the adjacent plutonic bodies. Some young grains were derived from thin felsic sills or veins that were unintentionally included in the sampled material. |
| GEOSCAN ID | 328053 |
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