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TitreThe crustal structure of the Eirik Ridge at the southern Greenland continental margin
AuteurFunck, T; Andrup-Henriksen, G; Dehler, S A; Louden, K E
SourceSt. John's 2012, Geoscience on the edge, Géoscience de pointe, Abstracts-Résumés; Association géologique du Canada-Association minéralogique du Canada, Réunion annuelle, Programme et résumés vol. 35, 2012 p. 47
LiensOnline - En ligne
Séries alt.Secteur des sciences de la Terre, Contribution externe 20110340
RéunionThe Geological Association of Canada (GAC) and the Mineralogical Association of Canada (MAC)Joint Annual Meeting; St. John's, NL; CA; mai 27-29, 2012
Documentpublication en série
Mediapapier; en ligne; numérique
ProvinceRégion extracotière
Lat/Long OENS-60.0000 -40.0000 61.0000 54.0000
ProgrammePreparation of a submission for an extended continental shelf in the Atlantic and Arctic Oceans under UNCLOS, Délimitation du plateau continental du Canada en vertu de la Convention des Nations Unies sur le droit de la mer (UNCLOS)
Résumé(disponible en anglais seulement)
In 2009, the SIGNAL (Seismic Investigations off Greenland, Newfoundland and Labrador) experiment was carried out to acquire marine refraction seismic data in the area between southern Greenland and Canada. Two lines were located on the Eirik Ridge off the southern tip of Greenland where two different continental margin styles merge. The SW Greenland continental margin is characterized by non-volcanic rifting associated with the opening of the Labrador Sea. Here, wide continentocean transition zones with serpentinized mantle are observed. In contrast, the later opening of the NE Atlantic formed volcanic-style margins off SE Greenland. The Eirik Ridge is a 300-km-long sediment drift and the SIGNAL experiment was designed to study the underlying crustal structure. SIGNAL line 3 is a 295-km-long refraction seismic line located on the top of the Eirik Ridge and extends into the Labrador Sea. Line 2 (225 km) crosses the ridge and continues into the NE Atlantic. Dense airgun shots were recorded by 24 and 20 ocean bottom seismometers (OBS) on lines 3 and 2, respectively. Preliminary velocity models indicate the presence of volcanic rocks, up to 4-km-thick on the ridge, which form a basement high beneath the ~2-km-thick sediment drift. A high-velocity lower crustal layer (7.1 to 7.5 km/s) with a thickness of up to 8 km underlies the ridge. Moho shallows from 17 km just off the shelf break to 13 km at the feather edge of the ridge. Seaward of the ridge, 4 to 5-kmthick
oceanic crust is observed in the Labrador Sea, while initial oceanic crust in the NE Atlantic has a thickness of 10 km. The models suggest that the ridge formed on transitional and initial oceanic crust created during the opening of the Labrador Sea. This crust was then modified by intrusions and extrusions associated with the volcanic style margin formation in the NE Atlantic around 56 Ma. Coincident reflection seismic data along the two SIGNAL lines indicate the presence of inner and outer seawarddipping reflection sequences separated by an outer basement high. This suggests a subaerial formation of the lavas on the ridge. Cooling and loss of dynamic support by the Iceland plume resulted in the subsidence of the ridge.