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Titolo:
Crustal thickness of V-shaped ridges south of the Azores: Interaction of the Mid-Atlantic Ridge (36 degrees-39 degrees N) and the Azores hot spot
Autore:
Escartin, J; Cannat, M; Pouliquen, G; Rabain, A; Lin, J;
Indirizzi:
Univ Paris 06, CNRS, IPGP,Inst Phys Globe, Lab Geosci Marines, F-75252 Paris 05, France Univ Paris 06 Paris France 05 b Geosci Marines, F-75252 Paris 05, France Univ Paris 07, CNRS, Inst Phys Globe, Lab Geosci Marines, F-75252 Paris, France Univ Paris 07 Paris France F-75252 Geosci Marines, F-75252 Paris, France Woods Hole Oceanog Inst, Woods Hole, MA 02543 USA Woods Hole Oceanog InstWoods Hole MA USA 02543 Woods Hole, MA 02543 USA
Titolo Testata:
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
fascicolo: B10, volume: 106, anno: 2001,
pagine: 21719 - 21735
SICI:
0148-0227(20011010)106:B10<21719:CTOVRS>2.0.ZU;2-2
Fonte:
ISI
Lingua:
ENG
Soggetto:
GRAVITY-ANOMALIES; SPREADING CENTER; UPPER-MANTLE; ULTRAMAFIC EXPOSURES; HOTSPOT INTERACTIONS; MAGMATIC ACCRETION; HYDROTHERMAL VENTS; MAGNETIC-ANOMALIES; TRIPLE JUNCTION; OCEANIC CRUSTAL;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
77
Recensione:
Indirizzi per estratti:
Indirizzo: Escartin, J Univ Paris 06, CNRS, IPGP,Inst Phys Globe, Lab Geosci Marines,Case 110,4 Pl Jussieu, F-75252 Paris 05, France Univ Paris 06 Case 110,4 Pl Jussieu Paris France 05 5, France
Citazione:
J. Escartin et al., "Crustal thickness of V-shaped ridges south of the Azores: Interaction of the Mid-Atlantic Ridge (36 degrees-39 degrees N) and the Azores hot spot", J GEO R-SOL, 106(B10), 2001, pp. 21719-21735

Abstract

V-shaped ridges propagating along the Mid-Atlantic Ridge axis south of theAzores and Iceland hot spots indicate that ridge-hot spot interactions produce temporal and spatial variations in melt supply to the ridge axis. Estimates of relative crustal thickness variations associated with the ridges south of the Azores hot spots, based on gravity and bathymetry data collected during the SudAcores cruise (1998), provide constraints on the rate of propagation of these melt anomalies and on the variations in melt production along the axis and in time. The maximum apparent crustal thickness along the Azores V ridge is similar to 14 km near the Azores, decreasing to normal crustal thickness of similar to6 km toward the south. This crustal thickness variation may be explained by enhanced melt production associated with the propagation of a mantle temperature anomaly that initiated similar to 10 Myr ago at the Azores hot spot. The temperature anomaly decreased as it propagated southward, reaching ambient mantle temperatures at the present timeat its predicted location under the axis. The excess melt was emplaced on axis forming discrete, shallow (< 1000 m) oceanic plateaus (similar to 100 km in diameter at similar to 37.5 degreesN) that are isostatically compensated. The numerous seamounts, lack of normal faults, and smooth basement at the summit of these plateaus suggest high effusion rates that persisted forsimilar to5 Myr or less, with little or no tectonic strain. As the melt anomaly propagated along axis, the magmatic activity at the plateaus ceased, resulting in rifting of the plateau and onset of normal seafloor spreading. The variations in crustal thickness inferred for the V ridges south of theAzores are at least twice that inferred for the Iceland structures. In both cases the V ridges record temporal variations in temperature and/or mantle flux that affect melt production under the ridge axis, but the fluctuations are larger for the Azores than for the Iceland hot spot.

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Documento generato il 29/03/20 alle ore 23:48:17