Influence of the Ringwoodite-Perovskite transition on mantle convection in spherical geometry as a function of Clapeyron slope and Rayleigh number
نویسندگان
چکیده
We investigate the influence on mantle convection of the negative Clapeyron slope ringwoodite to perovskite and ferro-periclase mantle phase transition, which is correlated with the seismic discontinuity at 660 km depth. In particular, we focus on understanding the influence of the magnitude of the Clapeyron slope (as measured by the Phase Buoyancy parameter, P ) and the vigour of convection (as measured by the Rayleigh number, Ra) on mantle convection. We have undertaken 76 simulations of isoviscous mantle convection in spherical geometry, varying Ra and P . Three domains of behaviour were found: layered convection for high Ra and more negative P , whole mantle convection for low Ra and less negative P , and transitional behaviour in an intervening domain. The boundary between the layered and transitional domain was fit by a curve P = αRa where α =−1.05, and β =−0.1, and the fit for the boundary between the transitional and whole mantle convection domain was α =−4.8, and β =−0.25. These two curves converge at Ra≈2.5×104 (well below Earth mantle vigour) and P ≈−0.38. Extrapolating to high Ra, which is likely earlier in Earth history, this work suggests a large transitional domain. It is therefore likely that convection in the Archean would have been influenced by this phase change, with Earth being at least in the transitional domain, if not the layered domain. Correspondence to: J. H. Davies ([email protected])
منابع مشابه
Numerical Simulation of the Thermal Convection and Subduction Process in the Mantle
The aim of this project is to make up a comprehensive model of the dynamics and evolution of the Earth's mantle, and to simulate phenomena related with subduction. (1) With the global modeling in Earth-like spherical shell geometry, we made systematic research on the convection patterns for the wide range of Rayleigh numbers with phase transitions. The experimentally and seismologically plausib...
متن کاملTopology of the postperovskite phase transition and mantle dynamics.
The postperovskite (ppv) phase transition occurs in the deep mantle close to the core-mantle boundary (CMB). For this reason, we must include in the dynamical considerations both the Clapeyron slope and the temperature intercept, T(int), which is the temperature of the phase transition at the CMB pressure. For a CMB temperature greater than T(int), there is a double crossing of the phase bounda...
متن کاملGeophysically Consistent Values of the Perovskite to Post-Perovskite Transition Clapeyron Slope
[1] The double-crossing hypothesis posits that postperovskite bearing rock in Earth’s D00 layer exists as a layer above the core-mantle boundary bounded above and below by intersections between a curved thermal boundary layer geotherm and a relatively steep phase boundary. Increasing seismic evidence for the existence of pairs of discontinuities predicted to occur at the top and bottom of this ...
متن کاملA note on the sensitivity of mantle convection models to composition-dependent phase relations
Numesical simulations of mantle convection are inhibit mantle circulation across such phase transitions and highly sensitive to the dependence of phase relations upon that strong time-dependent instabilitiesmay be induced near pressure, temperature, and composition. Phase transitions in phase boundaries. the (relatively silica-poor) olivine components of the manIn such studies, the phase transi...
متن کاملEffect of nanoparticle shape on natural convection heat transfer in a square cavity with partitions using water-SiO2 nanofluid
In this paper a numerical investigation is performed to study the effects of different nanofluids on convective heat transfer enhancement in a partitioned square cavity subject to different shapes of nanoparticle using water-SiO2 nanofluid. This study has been carried out to analyze the effects of SiO2 nanoparticle, its volumetric fraction between 2 and 4%, and nanoparticle shape (i.e. blades, ...
متن کامل