First published: 16 August 2016
Last modified:
DISCLAIMER: This English version is translated from the original French. In case of any discrepancy, the French version shall prevail.
| Author(s): | Taylor, 1982 |
| Age: | Paleoproterozoic |
| Stratotype: | None |
| Type area: | Pecten Harbour (NTS sheet 35F04) |
| Geological province: | Churchill Province |
| Geological subdivision: | Ungava orogen / Southern Domain |
| Lithology: | Granodiorite, tonalite |
| Category: | Lithodemic |
| Rank: | Lithodeme |
| Status: | Formal |
| Use: | Active |
None
Background
The Pecten Harbour Pluton was first described by Taylor (1982) who mentions that the intrusive nature of the pluton is confirmed by the presence of metavolcanic enclaves in the transition zone between the tonalitic facies of the pluton and volcanics to the ENE.
Description
The Pecten Harbour Pluton is a medium to coarse grained granodioritic to tonalitic rock that is locally K-feldspar porphyritic. It is generally mesocratic with a mafic phase consisting of hornblende and biotite. Muscovite and epidote are secondary phases (<5%), and pyrite, sphene and apatite are present in trace amounts. This unit includes a foliated to gneissic or schistose facies. Near the eastern contact, the pluton contains enclaves, some of which preserve pillow structures, confirming their volcanic nature. In addition, this contact zone has evidence of intense deformation (Barrette, 1990b).
Thickness and distribution
The pluton is semicircular and covers an area of >70 km². It occupies part of the coastline in sheet 35F04.
Dating
Rb/Sr dating on total rock gave an age of 1786 ±14 Ma (Taylor and Loveridge, 1985). This age is too young to belong to the Cape Smith Suite (1898-1836 Ma). It is, however, within the age range of the late suite of the Narsajuaq Arc (1803-1742 Ma; Dunphy et al., 1995).
| Unit | Sample Number | Isotopic System | Mineral | Crystallization Age (Ma) | (+) | (-) | Reference(s) |
| pPpec | Pecten Hbr pluton | Rb-Sr | Whole rock | 1786 | 14 | 14 | Taylor and Loveridge, 1985 |
Stratigraphic Relationship(s)
The Pecten Harbour Pluton intrudes into a tholeiitic basalt unit assigned to the Beauparlant Formation. A thrust fault brings the southern part of the pluton in contact with the Chukotat Group. The Pecten Harbour Pluton has foliations and plunging lineations along its edge that may indicate that it was transported with the allochthonous host.
Paleontology
Does not apply.
References
Publications Available Through SIGÉOM Examine
BARRETTE, P. D., 1990. Géologie de la région du lac Bolduc (Fosse de l’Ungava). MRN; ET 89-03, 48 pages, 3 plans.
LAMOTHE, D., 2007. Lexique stratigraphique de l’Orogène de l’Ungava. MRNF; DV 2007-03, 66 pages, 1 plan.
Other Publications
Taylor, F.C., 1982. Reconnaissance geology of a part of the Canadian Shield, northern Quebec and Northwest Territories Geological Survey of Canada, Memoir 399, 32 pages (7 sheets). https://doi.org/10.4095/109241
Suggested Citation
Ministère de l’Énergie et des Ressources naturelles (MERN). Pecten Harbour Pluton. Quebec Stratigraphic Lexicon. https://gq.mines.gouv.qc.ca/lexique-stratigraphique/province-de-churchill/pluton-de-pecten-harbour_en [accessed on Day Month Year].
Contributors
First publication | Isabelle Lafrance, P.Geo., M.Sc. isabelle.lafrance@mern.gouv.qc.ca (redaction) Mona Baker, P.Geo., M.Sc. (coordination); Claude Dion, P.Eng., M.Sc. (critical review); Simon Auclair, P.Geo., M.Sc. (editing); Céline Dupuis, P.Geo., Ph.D. (English version). |