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TitreEvolution of the Early to Middle Ordovician Popelogan Arc in New Brunswick, Canada, and adjacent Maine, USA: record of arc-trench migration and multiple phases of rifting
AuteurVan Staal, C R; Wilson, R A; Kamo, S L; McClelland, W C; McNicoll, V
SourceGeological Society of America Bulletin vol. 128, no. 1-2, 2016 p. 122-146, https://doi.org/10.1130/b31253.1
Année2016
Séries alt.Secteur des sciences de la Terre, Contribution externe 20160062
ÉditeurGeological Society of America
Documentpublication en série
Lang.anglais
DOIhttps://doi.org/10.1130/b31253.1
Mediapapier; en ligne; numérique
Formatspdf
ProvinceNouveau-Brunswick; Québec
SNRC21
Lat/Long OENS -73.0000 -65.0000 48.0000 44.0000
Sujetsantécédents tectoniques; évolution tectonique; interprétations tectoniques; datations au uranium-plomb; roches magmatiques; datations au zircon; arcs magmatiques; géochimie du zirconium; géochimie; tectonique; géophysique
Illustrationslocation maps; stratigraphic columns; geological sketch maps; schematic diagrams; graphs; photographs; tables; Concordia diagrams
ProgrammeÉtude des gîtes de sulfures massifs volcaniques, Initiative géoscientifique ciblée (IGC-4)
Résumé(disponible en anglais seulement)
A detailed tectonic analysis of the magmatic evolution of the Early to Middle Ordovician west-facing Popelogan arc in New Brunswick and adjacent Maine is presented based on combining new U-Pb zircon radiometric age dates (TIMS and SHRIMP) with existing age-constraints on the various magmatic events recognized in this arc system. The Popelogan arc has a life span of nearly 20 my (ca. 476-457 Ma) and becomes progressively younger towards the northwest. Existing lihogeochemical and isotope data combined with field relationships and new zircon inheritance data indicates that the Popelogan arc was built on the leading edge of Ganderia and represents a predominantly continental calc-alkaline arc. Incursions of arc to within plate-like tholeiitic magmatism correspond with rifting events temporally and spatially linked to trenchward migration of the arc magmatic axis, isolation of arc ribbons and formation of mafic oceanic and/or transitional crust in the associated Tetagouche backarc basin. Arc-trench migration and backarc basin opening were caused by a retreating subduction zone. Slab retreat prior to 467 Ma was at least partially accommodated by arc migration, but thereafter mainly by extension and spreading in the associated Tetagouche backarc basin. New U-Pb zircon radiometric age dates and lithogeochemistry of calc-alkaline felsic tuff beds interlayered with the oceanic backarc rocks of the Fournier Supergroup provide a direct link between the Tetagouche backarc rocks and coeval calc-alkaline arc activity in the Popelogan arc. The oldest incursion of arc tholeiite (470-467 Ma) corresponds with cessation of the ca. 475-470 Ma calc-alkaline Meductic phase of the Popelogan arc, the onset of the calc-alkaline Balmoral phase (467-457 Ma) further towards the west and formation of the oceanic and/or mafic-dominated transitional crust in the Canoe Landing Lake Formation of the Tetagouche backarc basin. A less well constrained second incursion of tholeiitic magmatism occurred somewhere between 465 and 459 Ma and corresponds to rifting of the Tetagouche ribbon and formation of the ophiolitic Devereaux Complex in the Fournier Supergroup. Cessation of calc-alkaline arc magmatism and eruption of transitional and/or alkalic mafic volcanic rocks between 459 and 455 Ma may represent slab-breakoff following accretion of the Popelogan arc to composite Laurentia and/or ridge subduction immediately prior to arc-continent collision.
Résumé(Résumé en langage clair et simple, non publié)
Évolution de l'arc de Popelogan datant de l'Ordovicien précoce à l'Ordovicien moyen, au Nouveau-Brunswick (Canada) et dans l'État adjacent du Maine (États-Unis) : données sur la migration de la zone de l'arc volcanique et de la fosse océanique, ainsi que sur les multiples phases de rifting à l'Ordovicien moyen. Des données géochronologiques et géochimiques nouvelles et existantes nous ont permis de documenter une analyse détaillée de l'évolution de l'arc de Popelogan au Nouveau-Brunswick et dans le Maine. Notre analyse démontre que l'arc a migré au fil du temps en raison du retrait de la plaque plongeante, qu'il s'est constitué sur la partie frontale du microcontinent Ganderia et qu'il a été soumis à plusieurs phases de rifting.
GEOSCAN ID298787