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Basaltic to andesitic volcaniclastic rocks in the Blake River Group, Abitibi Greenstone Belt: 1. Mode of emplacement in three areas

Ross, Pierre-Simon; Goutier, Jean; Mercier-Langevin, Patrick; Dubé, Benoît (2001). Basaltic to andesitic volcaniclastic rocks in the Blake River Group, Abitibi Greenstone Belt: 1. Mode of emplacement in three areas Canadian Journal of Earth Sciences , vol. 48 , nº 4. p. 728-756. DOI: 10.1139/e10-090.

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Résumé

The Archean Blake River Group (BRG) of Ontario and Québec is dominated by submarine mafic to intermediate lavas, with more restricted felsic volcanic rocks. Given the good quality of outcrop, and high level of preservation of some BRG rocks, the mafic to intermediate lavas were used in the 1970s and 1980s to better understand the evolution of massive and pillowed submarine flows, and their associated fragmental facies (pillow breccias, hyaloclastite). Potentially, the BRG could also represent a useful volcanic succession for the study of explosive submarine eruption products in the ancient record. Before this is possible, however, a regional inventory of the mafic to intermediate volcaniclastic units is needed in order to clarify their characteristics and origins. In this paper, we compare and contrast volcaniclastic rocks from three areas within the same formation of the northern BRG in Québec: the Monsabrais area, the lac Duparquet area, and the D’Alembert tuff area. Close examination reveals pronounced differences in terms of lateral continuity, thickness, grading, bedding, clast shapes, textures, etc. in the volcaniclastic rocks. These differences are interpreted to reflect vastly different emplacement processes ranging from hyaloclastite generation as a result of self-fragmentation and lava contact with water (dominant in the Monsabrais and lac Duparquet areas) to aqueous density currents likely fed directly by explosive submarine eruptions (dominant in the D’Alembert tuff).

Type de document:
Mots-clés libres: roche volcanique; Groupe archéen de Blake River; laves sous-marines mafiques à intermédiaires; rivière Blake; Monsabrais; lac Duparquet; tuf de D’Alembert; Abitibi
Centre: Centre Eau Terre Environnement
Date de dépôt: 17 déc. 2013 21:55
Dernière modification: 17 déc. 2013 21:55
URI: http://espace.inrs.ca/id/eprint/1899

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