Hot–spots are anomalous regions of magmatism that cannot be directly associated with plate tectonic processes. They are widely regarded as the surface expression of hot, columnar plumes, upwelling from deep within Earth’s 2900–km thick mantle. Hot–spots have variable life–spans, magmatic productivity and fixity. This suggests that a wide– range of upwelling structures co–exist within Earth’s ma...

D″ (Dee double prime), the lowermost layer of the Earth's mantle, is the thermal boundary layer (TBL) of mantle convection immediately above the Earth's liquid outer core. As the origin of upwelling of hot material and the destination of paleoslabs (downwelling cold slab remnants), D″ plays a major role in the Earth's evolution. D″ beneath Central America and the Caribbean is of particular geod...

Analyses of the relative motion using hotspot tracks, age progressions and plate circuits, and of the absolute motion using paleolatitude data indicate that three major long-lived surface hotspots geographically within a very low velocity province (VLVP) at the base of the Earth's mantle, Tristan, Marion and Kerguelen, exhibit small relative motions (b9 mm/yr) in the past 80 Ma. The geochemical...

a r t i c l e i n f o Some regions of the Earth's lowermost mantle exhibit anomalous seismic properties within a thin zone, less than tens of kilometers in thickness, that directly overlies the core-mantle boundary (CMB). These regions have been dubbed Ultra-Low Velocity Zones (ULVZs) due to their greater than 10% drop in seismic velocities. High resolution seismic array studies have found smal...

Continents, especially their Archean cores, are underlain by thick thermal boundary layers that have been largely isolated from the convecting mantle over billion-year timescales, far exceeding the life span of oceanic thermal boundary layers. This longevity is promoted by the fact that continents are underlain by highly melt-depleted peridotites, which result in a chemically distinct boundary ...

The deformation at the core-mantle boundary produced by the 2004 Sumatra earthquake is investigated by means of a semi-analytic theoretical model of global coseismic and postseismic deformation, predicting a millimetric coseismic perturbation over a large portion of the core-mantle boundary. Spectral features of such deformations are analysed and discussed. The time-dependent postseismic evolut...

The Earth’s magnetic field is measured on and above the crust, while turbulent dynamo in outer core produces values at core–mantle boundary (CMB). connection between two sets of usually assumed to be independent electrical conductivity mantle. However, magnetofluid a time-varying that must induce currents lower mantle as it emerges, since observed electrically conductive. Here, we develop model...

Seismic observations recorded by an African seismic array reveal a low velocity anomaly at the base of the mantle beneath the Indian Ocean, with steeply dipping edges, rapidly varying thicknesses and geometries, and anomalously low shear wave velocities decreasing from 32% at 200 km above the core^mantle boundary to 39% to 312% at the core^ mantle boundary (relative to the preliminary reference...

The possibility of reaction between the liquid iron of the Earth's outer core and crystalline silicates ((Mg, Fe)SiOa) of the mantle, MgO., Feo.•SiOa(pv) + O.15Fe(e) = 0.9MgSi03 (pv)+O.2FeO(hpp)+O.O5FeSi(•)+ O.05Si02(st), was proposed by Knittie and Jeanloz(1989,1991) on the basis of exploratory experiments. We calculate Gibbs free-energies for the reactants and the products of the above reacti...

[1] An SH hybrid method is developed for calculating synthetic seismograms involving twodimensional localized heterogeneous structures. The hybrid method is a combination of analytic and numerical methods, with the numerical method (finite difference) applied in the heterogeneous region only and analytical methods applied outside the region. Generalized ray theory solutions from a seismic sourc...