a r t i c l e i n f o Keywords: seismic anisotropy mantle flow geodynamic modeling shear wave splitting surface wave analysis mantle convection Observations of seismic anisotropy yield some of the most direct constraints available on both past and present-day deformation in the Earth's mantle. Insight into the character of mantle flow can also be gained from the geodynamical modeling of mantle ...

Introduction: Core-mantle differentiation is one of the most dramatic events in the Earth's history. As a result of core formation, the Earth's mantle is depleted in siderophile elements. Amounts of siderophile elements retained in the mantle give important clues for estimation of core formation condition. It is well known that the observed mantle abundance of Ni is larger than that predicted f...

S U M M A R Y This study applies high-resolution Radon transform to a large set of SS precursors and explores the mantle reflectivity structure beneath 17 potentially ‘deep-rooted’ hotspots. The combined reduced time (τ ) and ray parameter (p) information effectively constrains the depth, spatial distribution and sharpness of upper-/mid-mantle reflectors. The olivine to wadsleyite phase boundar...

[1] Although an average westward rotation of the Earth’s lithosphere is indicated by global analyses of surface features tied to the deep mantle (e.g., hot spot tracks), the rate of lithospheric drift is uncertain despite its importance to global geodynamics. We use a global viscous flow model to predict asthenospheric anisotropy computed from linear combinations of mantle flow fields driven by...

The measured inwards motion of Phobos provides a constraint on the tidal dissipation factor, Q, within Mars. We model viscoelastic dissipation inside a convective Mars using a modified Burgers model based on laboratory experiments on anhydrous, melt-free olivine. The model tidal Q is highly sensitive to the mantle potential temperature and grain size assumed, but relatively insensitive to the b...

We use seismic attenuation tomography to identify a region at the top of the lower mantle that displays very high attenuation consistent with an elevated water content. Tomography inversions with >80,000 differential travel-time and attenuation measurements yield 3D whole-mantle models of shear velocity (VS) and shear quality factor (Q ). The global attenuation pattern is dominated by the locat...

[1] The mantle plume model has been invoked to explain the formation of large igneous provinces (LIP) and associated age-progressive hotspot tracks. The shape of mantle plumes should be significantly altered by physical properties of the mantle and will influence how plume theory is used to interpret observational constraints. Based on theoretical analysis and numerical modeling, we explore the...

The chemical differences between deep- and shallow-mantle sources of oceanic basalts provide evidence that several distinct components coexist within the Earth's mantle. Most of these components have been identified as recycled in origin. However, the noble-gas signature is still a matter of debate and questions the preservation of primitive regions in the convective mantle. We show that a mode...

[1] Putative mechanisms that have been proposed to explain intraplate “hotspot” volcanism extensively depart from the early plume theory, and many do not involve deep mantle flow. Here, we look for a relationship between hotspot volcanism and mantle flow using flow models excited by density anomalies inferred from seismic tomography. We show that previously identified major hotspots are prefere...

Torsional Alfvén waves propagating in the Earth’s core have been inferred by inversion techniques applied to geomagnetic models. They appear to propagate across the core but vanish at the equator, exchanging angular momentum between core and mantle. Assuming axial symmetry, we find that an electrically conducting layer at the bottom of the mantle can lead to total absorption of torsional waves ...