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Showing 1 to 20 of 39 for “"Core-mantle boundary"”.
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Mapping the Core-Mantle Boundary Using Sdiff Postcursors
The core-mantle boundary – the interface between the rocky mantle and the fluid iron outer core – is host to a diverse collection of phenomena across all length scales. At the largest length scales, continent-sized structures characterised by low velocity anomalies lie opposite to each other on the …
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Seismic Evidence for Layering at the Core-Mantle Boundary
The core-mantle boundary (CMB) is the most extreme discontinuity in Earth's interior and plays an important role in regulating planetary scale processes, including convection in both the mantle and core. The CMB is usually treated as a sharp discontinuity with direct contact between the silicate …
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Seismic Imaging of Earth’s Core-Mantle Boundary using Diffracted Waves
Earth’s core-mantle boundary marks the transition from the rocky mantle to the liquid outer core and exhibits the most extreme velocity jump in the Earth’s radial seismic structure. In recent decades, seismological studies demonstrate that the seismic structure close to this boundary is far more …
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The character of the core-mantle boundary : a systematic study using PcP
Assuming that liquid iron alloy from the outer core interacts with the solid silicate-rich lower mantle the influence on the core-mantle reflected phase PcP is studied. If the core-mantle boundary is not a sharp discontinuity, this becomes apparent in the waveform and amplitude of PcP. …
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Imaging of structure at and near the core mantle boundary using a generalized radon transform
… at and near interfaces in Earth's lowermost mantle with broadband, three-component seismograms from Global Seismograph Networks (GSN). With this GRT method I transformed ~100,000 transverse-component ScS waveforms into image gathers of a core mantle boundary (CMB) patch beneath Central …
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The high temperature geochemistry of vanadium: From isotope ratios in ocean island basalt to thermal diffusion processes at the core-mantle boundary
… of peridotites, the dominant rock of upper mantle, and primitive meteorites show significant offset with the peridotites heavier by ~0.2 ‰, the largest offsets among all metal stable isotope systems. If primitive meteorites represent the primary building blocks of the Earth, Earth’s interior …
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The Evolution of the Galapagos Mantle Plume: From Large Igneous Province to Ocean Island Basalt
Mantle plumes are anomalously hot, narrow upwellings of mantle material that originate at the core-mantle boundary. As plumes rise they may form volumetrically large "heads" (~1000 km in diameter) with narrower (~100 km) "tails." Plume head melting is thought to form Large Igneous Provinces (LIPs), …
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Terrestrial magma ocean solidification and formation of a candidate D" layer
… and the formation of a deep dense layer at the core-mantle boundary. We also study the concentrations and densities of the last layers of the solidified magma ocean and how they create a deep dense layer after solid-state overturn. The deep dense layer that forms in our model matches the bulk …
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Low-degree convection with melting and application to the Martian northern hemisphere
… is robust I vary the model's initial conditions, core-mantle boundary temperature and radius, and the thickness of the lithospheric lid. Long-wavelength convection is a consistent result of the viscosity stratification, and degree-one occurs in one third of the numerical experiments. I compare the …
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Seismic and gravitational studies of melting in the mantle's thermal boundary layers
… tools to the task of better understanding mantle melting phenomena at the upper and lower boundaries of the mantle. The first study uses seafloor bathymetry and small variations in the gravitational acceleration over the Hawaii-Emperor seamount chain to constrain the changes in the igneous …
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Seismic and gravitational studies of melting in the mantle's thermal boundary layers
… tools to the task of better understanding mantle melting phenomena at the upper and lower boundaries of the mantle. The first study uses seafloor bathymetry and small variations in the gravitational acceleration over the Hawaii-Emperor seamount chain to constrain the changes in the igneous …
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Global isotopic signatures of oceanic island basalts
… is used to infer information about the Earth's mantle. Principal component analysis of the OIB+MORB data set shows that the first three principal components account for 97.5% of the variance of the data. Thus. only four mantle end-member components [EMI, EMII, HIMU and DMM] are required to …
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Global isotopic signatures of oceanic island basalts / by
… is used to infer information about the Earth's mantle. Principal component analysis of the OIB+MORB data set shows that the first three principal components account for 97.5% of the variance of the data. Thus, only four mantle end-member components [EMI, EMII, HIMU and DMM I are required to …
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Autocorrelation Analysis of the Seismic Data Recorded on Mars
… Moho, olivine-wadsleyite transition and core-mantle boundary. As for Mars orbiting surface waves, it can be used to improve the velocity models of Martian upper mantle.
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Stability of the large low shear velocity provinces
… of the subducted oceanic crust (OC) at the core mantle boundary and its ability to accumulate and form large thermochemical piles (such as the seismically observed Large Low Shear Velocity Provinces - LLSVPs). Our high-resolution numerical simulations suggest that the longevity of LLSVPs for …
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Imaging the lowermost mantle (D ") beneath the Pacific Ocean with SKKS coda waves
… high-resolution image of the lowermost mantle (400 kilometers above the core-mantle boundary) beneath the Pacific Ocean (125° E-75°W, 45° S-65°N in this work). More than 4,000,000 radial teleseismic traces from about 8,000 events (mb >= 5.8) between 1990 and 2015, globally recorded by …
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Seismic anisotropy and mantle flow beneath Africa and Arabia
… phenomena involve edge-driven small-scale mantle convection and the thermal or dynamic effects of one or more mantle plumes. In this study we use continental scale shear-wave splitting (SWS) measurements to provide additional constraints on the various models of rifting, uplifting, and …
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Insights into the location, nature and influence of mantle heterogeneity in the Galápagos mantle plume
… of the Earth's, highly heterogeneous, convecting mantle. Our view of the Earth's mantle is, however, partially obscured by processes that influence mantle-derived melts as they transition through the lithosphere (e.g. mixing, assimilation). Nevertheless, via careful consideration of the magmatic …
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Constraining the Radial Structure of Seismic Attenuation using Multiple S-Wave Datasets
… investigates the radial Q structure of Earth's mantle using amplitude measurements from core-diffracted S waves (Sdiff) and core-reflected S waves (ScS), along with direct S and multiply reflected S waves (SSSS).We analyze 7,598 Sdiff, 463 ScS, 5,940 S, and 1,726 SSSS measurements from 448 …
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The Influence of Curvature on Mantle Convection featuring a Temperature-dependent Viscosity
Convection in the silicate mantles or ice layers of terrestrial planets and moons is characterized by a strongly temperature-dependent viscosity. Mantle convection regime is first examined in 2D and 3D spherical geometry with varying mantle curvature (core-to-surface radii-ratio, f) and constant …
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