Where ρ0, α0, ∆T , η, κ are dimensional reference values of density of the background mantle, thermal expansivity, temperature difference between core-mantle boundary and surface, reference viscosity at temperature T = 0.5 (non-dimensional), and thermal diffusivity, respectively. g and h are dimensional gravitational acceleration and thickness of mantle, respectively. 1 Chemical complexity of h...

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...

A P-SV hybrid method is developed for calculating synthetic seismograms involving two-dimensional localized heterogeneous structures. The finite difference technique is applied in the heterogeneous region and generalized ray theory solutions from a seismic source are used in the finite difference initiation process. The seismic motions, after interacting with the heterogeneous structures, are p...

Cratonic mantle eclogite xenoliths occur with diamond-bearing kimberlite. The modes and mineral compositions of eclogite contain important information on their origin, physical-chemical conditions of formation, and their geophysical properties. We have used the pseudosection option of the program PERPLEX to explore how mineral assemblage, abundance, and composition vary with bulk composition, t...

Layered viscosity, temperature-dependent viscosity, and surface plates have an important effect on the scale and morphology of structure in spherical models of mantle convection. We find that long-wavelength structures can be produced either by a layered viscosity with a weak upper mantle or temperature-dependent viscosity even in the absence of surface plates, corroborating earlier studies. Ho...