Lithological and structural contexts of the sonny zinc showing in the meta-sedimentary belt of the Grenville Province in western Québec

Guyot-Messier, Laurence; Saumur, B.M.; De Souza, Stéphane; Perrault, S. et Desormiers, M. (2022). « Lithological and structural contexts of the sonny zinc showing in the meta-sedimentary belt of the Grenville Province in western Québec », dans GAC-MAC-IAH-CNC-CSPG 2022 Halifax Meeting: Abstracts, Volume 45 (GAC-MAC-IAH-CNC-CSPG, Halifax, 15-18 mai 2022), sous la dir. de Barr, S.. p. 118.

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Résumé

The Grenville Province is known for its zinc deposits, but significant examples, suchas Balmat-Edwards (NY), are rare and exploration models are nonetheless based onthe characteristics of such large occurrences. This study presents a recent zinc dis-covery and its lithological and structural contexts, with the aim of refiningfavourable environments to such mineralization in the Grenville Province. Discov-ered in 2014, the Sonny zinc showing is located at Ile-du-Grand-Calumet in Québec,100 km to the NW of Ottawa, within Mesoproterozoic marble units of theGrenville Metasedimentary Belt. A detailed map was completed on the southernportion of Ile-du-Grand-Calumet to characterize host rock stratigraphy, and to con-strain the roles of deformation and metamorphism on zinc distribution. The strati-graphic sequence is composed of meta-volcanic mafic rocks (1.232 Ga, U–Pb onzircon), garnet-biotite-sillimanite paragneiss, quartzofelsdpathic schist and dolomiticto calcitic marbles containing minor calc-silicate units and highly recrystallized chert.The metavolcanic rocks developed hornblende-clinopyroxene assemblages, withlocal orthopyroxene and quartz, indicating metamorphism varying from amphiboliteto granulite facies. The marble and associated mineralized layer are deformed andhighly recrystallized. As such, primary structures are rarely preserved within thesequence, making a determination of polarity difficult. The mineralization is strati-form and composed of sphalerite ± pyrite in centimetric layers. It is found exclu-sively in the marble, with a thickness of up to five metres, at 3.8% Zn. The miner-alized layer is also associated with an anhydrite-bearing layer within the marble,demonstrating an oxidizing shallow environment in arid conditions. At least threephases of ductile deformation are documented. The first one is characterized by iso-clinal E-dipping folds (F1). The second phase of deformation is characterized by E-plunging isoclinal folds (F2). This D2 phase explains the variation in the orientationof the S1 foliation in the northern portion of the mapped area. A complex hook-shaped interference pattern (Type III) results from the sum of these phases and thefolds show an important thickening within their hinge zones. The third phase offolding is represented by open E-W trending folds. This structural model makes itpossible to target prospective Zn zones at the scale of Ile-du-Grand-Calumet. Com-bined with geochronological and thermobarometric studies, it will contribute to therefinement of the geological models in this portion of the Grenville. In addition, theidentification of anhydrite-bearing and chert marker horizons provides metallotectsthat define a favourable environment for zinc mineralization.

Type:	Communication, article de congrès ou colloque
Mots-clés ou Sujets:	zinc, Pontiac, Outaouais, minéraux critiques
Unité d'appartenance:	Faculté des sciences > Département des sciences de la Terre et de l'atmosphère
Déposé par:	Benoit Saumur
Date de dépôt:	10 mars 2025 08:15
Dernière modification:	10 mars 2025 08:15
Adresse URL :	http://archipel.uqam.ca/id/eprint/18552

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