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TitleGeochemical variations in Middle Ordovician volcanic rocks of the northern Miramichi Highlands and their tectonic significance
Authorvan Staal, C R; Winchester, J A; Bedard, J H
SourceCanadian Journal of Earth Sciences 28, 1991 p. 1031-1049, Open Access logo Open Access
Alt SeriesGeological Survey of Canada, Contribution Series 45990
PublisherCanadian Science Publishing
Mediapaper; on-line; digital
File formatpdf
ProvinceNew Brunswick
NTS21O/01; 21O/02; 21O/07; 21O/08; 21O/09; 21O/10; 21O/15; 21O/16; 21P/03; 21P/04; 21P/05; 21P/06; 21P/11; 21P/12; 21P/13; 21P/14
AreaMiramichi Highlands
Lat/Long WENS -67.0000 -65.0000 48.0000 47.0000
Subjectsgeochemistry; tectonics; basalts; tholeiites; volcanic rocks; igneous rocks; geochemical analyses; tectonic environments; tectonic interpretations; metamorphism; petrography; magmatism; Tetagouche Group; Fournier Group; Ordovician; Paleozoic
Illustrationssketch maps; graphs; tables
AbstractA detailed geochemical study of Middle Ordovician volcanic rocks, undertaken in the northern Miramichi Highlands of New Brunswick, shows that 10 basaltic suites can be distinguished. These suites are assigned to the Tetagouche and Fournier groups. The contact between these two groups is a major thrust zone, marked for over 70 km by a prominent blueschist zone. All the Tetagouche Group volcanic rocks have chemistries consistent with extrusion in a continental rift, but most Fournier Group basalts in the Miramichi Highlands have chemistries suggestive of an oceanic back-arc setting. The chemical signatures, stratigraphic variations, and structural data indicate that the northern Miramichi Highlands preserve a section across a telescoped Middle Ordovician back-arc basin that initially opened as a result of asthenospheric injection near the rear part of a Lower Ordovician ensialic arc.

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