GEOSCAN, résultats de la recherche


TitreThe volcanic margins of the northern Labrador Sea: insights to the rifting process
AuteurKeen, C E; Dickie, K; Dehler, S A
SourceTectonics vol. 31, TC1011, 2012 p. 1-13,
Séries alt.Secteur des sciences de la Terre, Contribution externe 20110146
Documentpublication en série
Mediapapier; en ligne; numérique
Formatspdf; html
ProvinceRégion extracotière du nord; Région extracotière de l'est
Lat/Long OENS-64.0000 -44.0000 65.0000 58.0000
Sujetsmarges plaques; marges continentales; roches ignées; roches volcaniques; crevasses; décrochement horizontal; volcanisme; interpretations sismiques; interprétations de la pesanteur; tectonique; géophysique
Illustrationslocation maps; profiles; cross-sections
ProgrammeBaffin Bay Sedimentary Basins - Canadian Arctic Petroleum Systems East (CAPSE), GEM : La géocartographie de l'énergie et des minéraux
Résumé(disponible en anglais seulement)
A new interpretation of seismic reflection data on the continental margin of northern Labrador shows basement structures similar to those observed on other volcanic rifted margins. Seaward dipping reflections, inner flows, volcanic plateaus, and lava deltas are observed on these data. Magnetic chron 27n (?61 Ma) is coincident with the volcanic plateaus, connecting these features to the Paleocene volcanism farther north in Davis Strait. Therefore, we are able to extend the region of volcanism about 500 km south along the margin. Similar structures are also observed on the conjugate west Greenland margin. Below the volcanic plateaus, gravity and wide-angle seismic data show thick igneous crust, which is fairly symmetrically distributed across the conjugate margins. However, the geometry of the thinned continental crust is not symmetrical: a narrower zone of thinning is observed off northern Labrador. The thick igneous crust lies seaward of thinned continental crust, which exhibits little or no underplating by the magmatic event. This observation is compatible with recent models for the formation of nonvolcanic margins, followed by a magmatic event late in the rift evolution. In Mesozoic time rifting of the cold, thick cratonic lithosphere occurred between Greenland and North America with minimal volcanic activity. Then in Late Cretaceous time, the zone of rifting narrowed and localized seaward of the shelf, creating a relatively narrow zone of lower lithospheric thinning and mantle upwelling into which the Paleocene magmas were eventually channeled. This scenario is supported by studies of Mesozoic igneous rocks on land in coastal west Greenland and Labrador.