Structure sismique de la ride de péridotite a l'ouest du Banc de Galice (ouest Ibérie)  [Seismic structure of the peridotite ridge west of the Galicia Bank, West Iberia]

Alternate Title(s): Seismic structure of the peridotite ridge west of the Galicia Bank, West Iberia
Author(s): Recq, M.; Whitmarsh, R. B.; Sibuet, J. C.; White, R. S.; Lyness, D.
Author Affiliation(s): Primary:
Université de Bretagne Occidentale, Département des Sciences de la Terre, Brest, France
Other:
IFREMER, Plouzane, France
Volume Title: Comptes Rendus de l'Académie des Sciences, Série II. Sciences de la Terre et des Planètes
Source: Comptes Rendus de l'Académie des Sciences, Série II. Sciences de la Terre et des Planètes, 322(7), p.571-578. Publisher: Gauthier-Villars, Montrouge, France. ISSN: 1251-8050
Note: In French with English summary. 27 refs.
Summary: Refraction profiles have been carried out along and across the peridotite ridge at the ocean-continent boundary west of the Galicia margin. Deep sea drilling (ODP Leg 103) shows that the ridge is composed of serpentinized peridotite. The shallow seismic velocity within the ridge is as low as 3.70 km/s, denoting a high grade of serpentinization. Modelling the ridge illustrates its heterogeneity and the large extent of the serpentinization from the crest to 6-8 km below sea floor. A unique downward velocity gradient within the ridge is ruled out. At a depth of 3 km below sea floor, the velocity gradient decreases abruptly through a second order discontinuity bisecting the ridge from west to east. Within a west-dipping transition zone at a depth of roughly 11 km, velocities increase from 7.40 to 7.65 km/s.
Year of Publication: 1996
Research Program: ODP Ocean Drilling Program
Key Words: 20 Geophysics, Applied; Atlantic Ocean; Bathymetry; Continental crust; Continental margin; Crust; Discontinuities; Dredging; Drilling; Elastic waves; Europe; Galicia Spain; Geophysical methods; Geophysical surveys; Iberian Peninsula; Igneous rocks; Leg 103; Leg 105; Mantle; Marine methods; Metasomatism; Models; North Atlantic; Northeast Atlantic; ODP Site 647; Ocean Drilling Program; Ocean floors; Oceanic crust; Offshore; Peridotites; Plutonic rocks; Seismic methods; Seismic waves; Seismograms; Serpentinization; Southern Europe; Spain; Surveys; Synthetic seismograms; Thermal circulation; Transition zones; Ultramafics; Upper mantle; Velocity structure
Coordinates: N420042 N420918 W0121054 W0125148
N531954 N531954 W0451542 W0451542
Record ID: 1996049272
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from PASCAL, Institute de l'Information Scientifique et Technique, Vandoeuvre-les-Nancy, France