Results 241 to 250 of about 771,265 (286)

Heterogeneous lithospheric mantle

2021
<p>The lithosphere is a thermal boundary layer atop mantle convection and a chemical boundary layer formed by mantle differentiation and melt extraction. The two boundary layers may everywhere have different thicknesses. Worldwide, the thicknesses of thermal and chemical boundary layers vary significantly, reflecting thermal and ...
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Mantle flow models with core‐mantle boundary constraints and chemical heterogeneities in the lowermost mantle

Journal of Geophysical Research: Solid Earth, 2008
Decorrelation between s‐wave and bulk sound velocities in the lowermost mantle and explicit density models based on seismic tomography give evidence for non‐thermal lateral density variations in the lowermost mantle. Here we implement such variations in a numerical model of mantle flow driven by density anomalies which are derived from seismic ...
Steinberger, B., Holme, R.
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Small-Scale Heterogeneities of the Upper Mantle

1997
Models derived from controlled source seismology (reflection and refraction data) and long-period seismology provide the impression that the upper mantle is rather homogeneous. For near-vertical reflections the mantle appears transparent if compared to the reflective lower crust.
Wenzel, Friedemann, Fuchs, Karl, Tittgemeyer, Marc, Ryberg, Trond   +3 more
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Seismic heterogeneity in the upper mantle

Journal of Geophysical Research: Solid Earth, 1994
This paper gives an overview of recent seismological evidence on heterogeneity in the upper mantle. While there is a growing consensus among seismologists on the low‐order spherical harmonic expansion of upper mantle structure, short‐ and intermediate‐wavelength features remain the subject of intense debate.
G. Nolet, S. P. Grand, B. L. N. Kennett
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Early Earth mantle heterogeneities

2023
Determining isotopic signatures established in the Hadean mantle offers far-reaching insights into the origin of Earth’s accreted building blocks, core formation, mantle differentiation as well as the formation of Earth’s first crust. Despite the masking effects of convective mantle homogenization and crustal recycling, rare isotopic heterogeneities ...
Meßling, Nils, Willbold, Matthias, Georg-August-Universität Göttingen, Willbold, Matthias, Pack, Andreas, Thiel, Volker, Müller, Thomas, Wörner, Gerhard, Stracke, Andreas   +8 more
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Chemical and seismological constraints on mantle heterogeneity

Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, 2002
Recent seismological studies that use scattered waves to detect heterogeneities in the mantle reveal the presence of a small, distributed elastic heterogeneity in the lower mantle which does not appear to be thermal in nature. The characteristic size of these heterogeneities appears to be ca.
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Confidence regions for mantle heterogeneity

Journal of Geophysical Research: Solid Earth, 1994
Least squares tomographic models of mantle P and S velocity structure from travel times have shown large‐scale variations correlated with surface tectonic features, as well as coherent structures in the lowermost mantle. The reliability of these global features of velocity models depends on whether velocity throughout the features can be estimated well
R. Jay Pulliam, Philip B. Stark
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Deep subduction and mantle heterogeneities

Tectonophysics, 1987
Abstract The globe-encircling isotopic anomaly centred on latitude 30°S defined from the geochemistry of mid-ocean ridge and particularly intraplate basalts has been previously shown to be correlative with degree-2 features of the Earth's geoid. The same region appears to show a correlation with zones of low seismic velocities, perhaps indicative of ...
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Lateral heterogeneity in the convecting mantle

Journal of Geophysical Research: Solid Earth, 1986
Thermally induced lateral heterogeneity in the earth's mantle has been studied in terms of idealized two‐dimensional, constant viscosity, numerical models of mantle convection. Steady model solutions of the temperature and velocity fields were analyzed with respect to both the spatial and spectral signatures of their inherent lateral heterogeneity.
G. T. Jarvis, W. R. Peltier
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Lateral heterogeneity and mantle dynamics

Nature, 1975
Recent work on the nature of the Earth's lateral heterogeneities yields two conclusions with implications for mantle dynamics: seismic velocity differences between continents and oceans extend to depths exceeding 400 km, and strong lateral velocity gradients at depths greater than 800 km characterise the mantle beneath many subduction zones.
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