Phase Velocities of Rayleigh Waves in the MELT Experiment on the East Pacific Rise

Forsyth, Donald W.; Webb, Spahr C.; Dorman, LeRoy M.; Shen, Yang

doi:10.1126/science.280.5367.1235

Cited by 204 publications

(168 citation statements)

References 12 publications

Supporting

Mentioning

154

Contrasting

Unclassified

Order By: Relevance

“…2000]. Similar seismic anomalies in the MELT region beneath the East Pacific Rise have been taken to indicate the presence of melt in mantle peridotite at temperatures greater than 1300°C [Forsyth et al, 1998a;Forsyth et al, 1998b]. A similar inference may be warranted for the mantle beneath NE Japan, though temperatures could be lower because H 2 O will stabilize mantle melts at lower temperatures.…”

Section: Seismic Constraints On Melt Distribution In the Uppermost Mamentioning

confidence: 80%

Thermal structure due to solid-state flow in the mantle wedge beneath arcs

Kelemen

Rilling

Parmentier

et al. 2003

Inside the Subduction Factory

191

177

View full text Add to dashboard Cite

We summarize petrological and seismic constraints on the temperature of arc lower crust and shallow mantle, and show that published thermal models are inconsistent with these constraints. We then present thermal models incorporating temperature-dependent viscosity, using widely accepted values for activation energy and asthenospheric viscosity. These produce thin thermal boundary layers in the wedge corner, and an overall thermal structure that is consistent with other temperature constraints. Some of these models predict partial melting of subducted sediment and/or basalt, even though we did not incorporate the effect of shear heating We obtain these results for subduction of 50 Myr old oceanic crust at 60 km/Myr, and even for subduction of 80 Myr old crust at 80 km/Myr, suggesting that melting of subducted crust may not be not restricted to slow subduction of young oceanic crust.

show abstract

Section: Seismic Constraints On Melt Distribution In the Uppermost Mamentioning

confidence: 80%

Thermal structure due to solid-state flow in the mantle wedge beneath arcs

Kelemen

Rilling

Parmentier

et al. 2003

Inside the Subduction Factory

191

177

View full text Add to dashboard Cite

show abstract

“…Motivated by an interest in observed asymmetries in tomographic images [e.g., Forsyth et al, 1998b;Dunn and Forsyth, 2003], I have extended the simulation code described by Katz [2008] to optionally model both sides of the ridge axis, without any assumption regarding symmetry. Indeed, this allows for symmetry-breaking boundary conditions such as ridge migration and large-scale temperature gradients; these are explored in detail below.…”

Section: Model Descriptionmentioning

confidence: 99%

“…Scheirer et al [1998] analyzed shipboard measurements of gravity, seamount distribution, and subsidence rate in the MELT region and found consistent asymmetry among these indicators. Forsyth et al [1998b] used Rayleigh wave tomography to image the shear wave velocity structure of the mantle between 20 and 70 km depth in the same geographic area. Their results exhibited a broad region of anomalously slow velocities, centered to the west of the ridge axis, that they attribute to the presence of partial melt.…”

Section: Introductionmentioning

confidence: 99%

Porosity‐driven convection and asymmetry beneath mid‐ocean ridges

Katz

2010

Geochem Geophys Geosyst

View full text Add to dashboard Cite

[1] Seismic tomography of the asthenosphere beneath mid-ocean ridges has produced images of wave speed and anisotropy that are asymmetric across the ridge axis. These features have been interpreted as resulting from an asymmetric distribution of upwelling and melting. Using computational models of coupled magma/mantle dynamics beneath mid-ocean ridges, I show that such asymmetry should be expected if buoyancy forces contribute to mantle upwelling beneath ridges. The sole source of buoyancy considered here is the dynamic retention of less dense magma within the pores of the mantle matrix. Through a scaling analysis and comparison with a suite of simulations, I derive a quantitative prediction of the contribution of such buoyancy to upwelling; this prediction of convective vigor is based on parameters that, for the Earth, can be constrained through natural observations and experiments. I show how the width of the melting region and the crustal thickness, as well as the susceptibility to asymmetric upwelling, are related to convective vigor. I consider three causes of symmetry breaking: gradients in mantle potential temperature and composition and ridge migration. I also report that in numerical experiments performed for this study, the fluid dynamical instability associated with porosity/shear band formation is not observed to occur.

show abstract

“…The emphasis in this paper is on structure to the east of the ridge, because the seafloor to the west subsides anomalously slowly, is populated by an unusual density of seamounts, and is poorly constrained by the MT coverage. Unlike the conductivity structure, the shear structure in the uppermost 60 km of the mantle is required by the Rayleigh wave data to be azimuthally anisotropic 9,10,11 , with a fast direction perpendicular to the ridge consistent with the fast polarization direction observed from shear-wave splitting analyses 4 . (A discussion of whether electrical anisotropy can be resolved above 60 km is included in supplemental material.)…”

mentioning

confidence: 99%

Geophysical evidence from the MELT area for compositional controls on oceanic plates

Evans¹,

Hirth²,

Baba

et al. 2005

Nature

222

210

View full text Add to dashboard Cite

Magnetotelluric (MT) and seismic data, collected during the MELT experiment at the Southern East Pacific Rise (SEPR) 1,2 , constrain the distribution of melt beneath this mid-ocean-ridge spreading center and also the evolution of the oceanic lithosphere during its early cooling history. In this paper, we focus on structure imaged at distances ~100 to 350 km east of the ridge crest, corresponding to seafloor ages of ~1.3 to 4.5 Ma, where the seismic and electrical conductivity structure is nearly constant, independent of age. Beginning at a depth of about 60 km, there is a large increase in electrical conductivity and a change from isotropic to transversely anisotropic electrical structure with higher conductivity in the direction of fast propagation for seismic waves. Because conductive cooling models predict structure that increases in depth with age, extending to about 30 km at 4.5 Ma, we infer that the structure of young oceanic plates is instead

show abstract

Phase Velocities of Rayleigh Waves in the MELT Experiment on the East Pacific Rise

Cited by 204 publications

References 12 publications

Thermal structure due to solid-state flow in the mantle wedge beneath arcs

Thermal structure due to solid-state flow in the mantle wedge beneath arcs

Porosity‐driven convection and asymmetry beneath mid‐ocean ridges

Geophysical evidence from the MELT area for compositional controls on oceanic plates

Contact Info

Product

Resources

About