Reykjanes "V"-shaped ridges originating from a pulsing and dehydrating mantle plume.
Nature
; 411(6838): 681-4, 2001 Jun 07.
Article
em En
| MEDLINE
| ID: mdl-11395767
ABSTRACT
Prominent crustal lineations straddle the Reykjanes ridge, south of Iceland (Fig. 1). These giant V-shaped features are thought to record temporal variations in magma production at the Reykjanes ridge axis, associated with along-axis flow of Icelandic plume material. It has been proposed that this flow is channelled preferentially along the ridge axis, and that temporal variability is induced by fluctuations of the Iceland plume itself or, alternatively, by relocations of the ridge axis on Iceland. Here I present a geodynamic model that predicts the formation of crustal V-shaped ridges from a pulsing and radially flowing mantle plume. In this model, plume pulses produce mantle temperature perturbations that expand away from the plume in all directions beneath the zone of partial melting. The melting zone has a high viscosity owing to mantle dehydration at the onset of partial melting. This high-viscosity region allows for reasonable variations in crustal thickness, produces crustal Vs that extend hundreds of kilometres along the axis, and prevents the plume material from being preferentially channelled along the ridge axis. The angle of the crustal V-shaped features relative to the ridge axis reflects the rate of lateral plume flow, which remains several times greater than the ridge half-spreading rate over the length of a crustal V. Consequently, this radially expanding plume produces lineations in crustal thickness and free-air gravity anomalies that appear to be nearly straight.
Buscar no Google
Coleções:
01-internacional
Base de dados:
MEDLINE
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Nature
Ano de publicação:
2001
Tipo de documento:
Article