Silica is the most abundant oxide component in the Earth mantle by weight, and stishovite, the rutile-structured (P4(2)/mnm) high-pressure phase with silica in six coordination by oxygen, is one of the main constituents of the basaltic layer of subducting slabs. It may also be present as a free phase in the lower mantle and at the core-mantle boundary. Pure stishovite undergoes a displacive pha...

Global analysis of NASA Magellan image data indicates that a major concentration of volcanic centers covering approximately 40 percent of the surface of Venus occurs between the Beta, Atla, and Themis regiones. Associated with this enhanced concentration are geological characteristics commonly interpreted as rifting and mantle upwelling. Interconnected low plains in an annulus around this conce...

The boundary between the rocky mantle and iron core, almost 2900 km below the surface, is physically the most significant in the Earth's interior. It may be the terminus for subducted surface material, the source of mantle plumes and a control on the Earth's magnetic field. Its properties also have profound significance for the thermochemical and dynamic evolution of the solid Earth. Evidence f...

a Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, USA b Department of Geoscience, University of Calgary, Calgary, AB, Canada c Department of Earth and Planetary Science, Washington University, St. Louis, MO 63130, USA d Department of Earth Sciences, Durham University, Durham, DH1 3LE, UK e Center for Applied Energy Research and Department of Earth & Environm...

Introduction: The orbit of Phobos is secularly decaying at a rate which implies that Mars is highly dissipative; even more so than Earth’s mantle. Most tidal dissipation on Earth occurs within the oceans. Where and how the tidal energy dissipation occurs within Mars is not presently well constrained. We examine several alternatives, including a uniformly warm mantle, a partial melt zone within ...

One of the principal means of understanding upper mantle dynamics involves inferring mantle flow directions from seismic anisotropy under the assumption that the seismic fast direction (olivine a axis) parallels the regional flow direction. We demonstrate that (i) the presence of melt weakens the alignment of a axes and (ii) when melt segregates and forms networks of weak shear zones, strain pa...

A long-standing question in the planetary sciences asks what the Earth is made of. For historical reasons, volatile-depleted primitive materials similar to current chondritic meteorites were long considered to provide the `building blocks' of the terrestrial planets. But material from the Earth, Mars, comets and various meteorites have Mg/Si and Al/Si ratios, oxygen-isotope ratios, osmium-isoto...

In preparation to the experimental results which will be available in the future, we consider geo-neutrino production in greater detail than in [F. Mantovani et al., arXiv:hep-ph/0309013], putting the basis for a more refined model. We study geo-neutrino production for different models of matter circulation and composition in the mantle. By using global mass balance for the Bulk Silicate Earth,...

It is possible that the majority of Earth’s H2O budget is present as hydroxyl (OH) structurally incorporated into the major nominally anhydrous minerals (NAMs) of the mantle (e.g., Martin and Donnay 1972). Ringwood (1966) thought as much as fi ve times the surface H2O-mass could be present in the mantle, amounting to ~0.2 wt% H2O if distributed throughout the entire mantle (Harris and Middlemos...