Radial profiles of temperature and viscosity in the Earth's mantle inferred from the geoid and lateral seismic structure

Čadek, O.; Berg, A. P. van den

doi:10.1016/s0012-821x(98)00244-1

Cited by 18 publications

(4 citation statements)

References 37 publications

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“…1) which is consistent with inversions of the long-wavelength geoid (Čadek and van den Berg, 1998;Ricard and Bai, 1991) and of observables related to post-glacial rebound (Tosi et al, 2005;Mitrovica and Forte, 2004;Forte and Mitrovica, 2001). An activation volume is implicit in equation (2) and is lower than 5 cm 3 /mol throughout the mantle but it has a non-monotonic Influences of Lower-Mantle Properties on the Formation of Asthenosphere in Oceanic Upper Mantle 145 character (Wentzcovich et al, 2009).…”

Section: Model Description Rheology and Materials Parameterssupporting

confidence: 77%

Influences of lower-mantle properties on the formation of asthenosphere in oceanic upper mantle

2011

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Asthenosphere is a venerable concept based on geological intuition of Reginald Daly nearly 100 years ago. There have been various explanations for the existence of the asthenosphere. The concept of a plume-fed asthenosphere has been around for a few years due to the ideas put forth by Yamamoto et al.. Using a two-dimensional Cartesian code based on finite-volume method, we have investigated the influences of lower-mantle physical properties on the formation of a low-viscosity zone in the oceanic upper mantle in regions close to a large mantle upwelling. The rheological law is Newtonian and depends on both temperature and depth. An extended-Boussinesq model is assumed for the energetics and the olivine to spinel, the spinel to perovskite and perovskite to post-perovskite (ppv) phase transitions are considered. We have compared the differences in the behavior of hot upwellings passing through the transition zone in the mid-mantle for a variety of models, starting with constant physical properties in the lower-mantle and culminating with complex models which have the post-perovskite phase transition and depth-dependent coefficient of thermal expansion and thermal conductivity. We found that the formation of the asthenosphere in the upper mantle in the vicinity of large upwellings is facilitated in models where both depth-dependent thermal expansivity and conductivity are included. Models with constant thermal expansivity and thermal conductivity do not produce a hot low-viscosity zone, resembling the asthenosphere. We have also studied the influences of a cylindrical model and found similar results as the Cartesian model with the important difference that upper-mantle temperatures were much cooler than the Cartesian model by about 600 to 700 K. Our findings argue for the potentially important role played by lower-mantle material properties on

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Section: Model Description Rheology and Materials Parameterssupporting

confidence: 77%

Influences of lower-mantle properties on the formation of asthenosphere in oceanic upper mantle

2011

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“…Woodhouse, 1996a, 1996b;Su and Dziewonski, 1997;Kennett et al, 1998;Masters et al, 2000]. The density to velocity heterogeneity ratio R•,/sv can also be estimated through the geodynamic modeling of geoid based on tomographic models [e.g., Forte et al, 1993Forte et al, , 1994bCorrieu et al, 1994;Cadek and van den Berg, 1998;Cadek and Fleitout, 1999;Forte, 2000] or through the inversion of normal mode data together with gravity data [Ishii and Tromp, 1999]…”

Section: Definitions Geophysical Observations and General Relationsmentioning

confidence: 99%

Origin of lateral variation of seismic wave velocities and density in the deep mantle

Karato¹,

Karki²

2001

J. Geophys. Res.

282

302

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Abstract. Strong constraints can be placed on the origin of heterogeneity of seismic wave velocities and density if the observed ratios of various parameters are compared with mineral physics predictions. They include the shear to compressional wave velocity heterogeneity ratio, Rs/p --• log Vs /• log Vp, the bulk sound to shear wave velocity heterogeneity ratio, R•/s --6 log V• /6 log Vs, and the density to velocity heterogeneity ratio, R,,,,p --6 log p /6 log V,,p.

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“…Cadek and van den Berg, 1998). Variance reduction is generally better for slab based density models.…”

Section: The Static Models-fitting the Observed Geoidmentioning

confidence: 99%

On the effect of a low viscosity asthenosphere on the temporal change of the geoid—A challenge for future gravity missions

Marquart¹,

Steinberger²,

Niehuus

2005

Journal of Geodynamics

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Radial profiles of temperature and viscosity in the Earth's mantle inferred from the geoid and lateral seismic structure

Cited by 18 publications

References 37 publications

Influences of lower-mantle properties on the formation of asthenosphere in oceanic upper mantle

Influences of lower-mantle properties on the formation of asthenosphere in oceanic upper mantle

Origin of lateral variation of seismic wave velocities and density in the deep mantle

On the effect of a low viscosity asthenosphere on the temporal change of the geoid—A challenge for future gravity missions

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