Three-dimensional numerical simulations of convection and magnetic ®eld generation in the Earth’s core now span several hundred thousand years; the magnetic ®eld created during most of this time has an intensity, structure and time dependence similar to the present geomagnetic ®eld. Five models are described here. The ®rst is a homogeneous Boussinesq model, driven steadily by heat sources on th...

The surface of Venus is so hot that the lower crust may be weak enough to allow decoupling of mantle and crust. An analytic model of such decoupling assumes that the shallow mande forms the top boundary layers of large scale mantle convection cells. Crustal flow is driven by the motion of the marie and by topographically induced pressure gradients. The model predicts that the lowest lowlands ar...

From iodine-plutonium-xenon isotope systematics, we re-evaluate time constraints on the early evolution of the Earth-atmosphere system and, by inference, on the Moon-forming event. Two extinct radioactivites (I, T1/2 = 15.6 Ma, and Pu, T1/2 = 80 Ma) have produced radiogenic Xe and fissiogenic Xe, respectively, within the Earth, which related isotope fingerprints are seen in the compositions of ...

We review recent developments in the study of volcanism and tectonics on Venus. Venus’s crust is basaltic, dry, and probably about 30 km thick. The mantle convects, giving rise to plumes, and has a similar composition and mean temperature (∼1300◦C), but a higher viscosity (∼1020 Pa s), than that of the Earth. Inferred melt generation rates constrain the lithospheric thickness to between 80 and ...

The equilibrium iron isotope fractionation between lower mantle minerals and metallic iron at core-mantle boundary conditions can be evaluated from the high-pressure 57Fe partial vibrational density of states determined by synchrotron inelastic nuclear resonant x-ray scattering spectroscopy using a diamond anvil. Ferropericlase [(Mg,Fe)O] and (Fe,Mg)SiO3- post-perovskite are enriched in heavy i...

Minerals recovered from the deep mantle provide a rare glimpse into deep Earth processes. We report the first discovery of ferric iron-rich majoritic garnet found as inclusions in a host garnet within an eclogite xenolith originating in the deep mantle. The composition of the host garnet indicates an ultrahigh-pressure metamorphic origin, probably at a depth of ~200 km. More importantly, the fe...

Abteilung Isotopengeologie, Geowissenschaftliches Zentrum, Georg-August-Universität Göttingen, 37073 Göttingen, Germany; Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, 199034 St. Petersburg, Russia; CAS Key Laboratory of Crustal-Mantle Materials and Environments, School of Earth and Space Science, University of Science and Technology of China, Hefei, 230026, Ch...

[1] The scaling of plate tectonic convection is investigated by simulating thermal convection with pseudoplastic rheology and strongly temperature‐dependent viscosity. The effect of mantle melting is also explored with additional depth‐dependent viscosity. Heat flow scaling can be constructed with only two parameters, the internal Rayleigh number and the lithospheric viscosity contrast, the lat...

In preparation to the experimental results which will be available in the future, we study geo-neutrino production for different models of mantle convection and composition. By using global mass balance for the Bulk Silicate Earth, the predicted flux contribution from distant sources in the crust and in the mantle is fixed within a total uncertainty of ±15%. We also discuss regional effects, pr...