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TitreEarly Cretaceous opening of the North Atlantic Ocean: Implications of the petrology and tectonic setting of the Fogo Seamounts off the SW Grand Banks, Newfoundland
AuteurPe-Piper, G; Piper, D J W; Jansa, L F; DeJong, A
SourceGeological Society of America Bulletin vol. 119, no. 5/6, 2007 p. 712-724,
Séries alt.Secteur des sciences de la Terre, Contribution externe 20060021
ÉditeurGeological Society of America
Documentpublication en série
Mediapapier; en ligne; numérique
ProvinceRégion extracotière de l'est
Lat/Long OENS-54.0000 -48.0000 45.0000 40.0000
Sujetstectonique de plaques; interprétations tectoniques; milieux tectoniques; évolution tectonique; cadre tectonique; volcanisme; roches volcaniques; magmatisme; convection; fusion partielle; caractéristiques structurales; crevasses; failles; formation de failles; monts sous-marins; marges continentales; marges continentales, atlantique; Système de rift d'Iberia-Grand Banks; tectonique; géologie marine; pétrologie ignée et métamorphique; géochronologie; géochimie; Mésozoïque; Crétacé
Illustrationslocation maps; cartoons; tables; seismic profiles; logs; plots
ProgrammeSécurité de l'approvisionnement énergétique du Canada
ProgrammeCRSNG Conseil de recherches en sciences naturelles et en génie du Canada
ProgrammeLe Programme de recherche et de développement énergétiques (PRDE)
Diffusé2007 05 08
Résumé(disponible en anglais seulement)
The Lower Cretaceous Fogo Seamounts and the J-Anomaly Ridge formed along the transform margin of the southwestern Grand Banks synchronous with volcanism on the adjacent continental shelf off southeastern Canada. This volcanism took place during the "nonvolcanic" rifting of Iberia from the Grand Banks. Chemical composition and radiogenic isotopes show that basalts from the seamounts range from mildly alkalic to mildly tholeiitic. The voluminous tholeiitic magmas resulted principally from decompression melting, and the ocean-islandbasalt signature of the alkalic rocks also suggests upwelling of deeper asthenosphere. The distribution of the seamounts has been determined from magnetic, bathymetric, and seismic data. Some seamounts are fl attopped and resemble guyots in that they are capped by carbonate-platform rocks. The distribution of the seamounts suggests that they developed from edge-controlled convection in the upper mantle due to thermal and density gradients at the transform transition between the spreading ocean and the continental block of the Grand Banks. The thermal effects of the volcanism promoted mid-crustal partial melting and detachment
faulting on the Grand Banks and the development of the asymmetric Grand Banks - Iberia rift system. The location of the volcanic centers was strongly infl uenced by crustal-scale strike-slip faulting. Although the Fogo Seamount chain thus has a different tectonic origin
compared with many oceanic seamount chains, the young seamounts from another area, off the transform Californian margin, also show many geochemical similarities and may have a similar origin.