Dynamical consequences of depth-dependent thermal expansivity and viscosity on mantle circulations and thermal structure

摘要: The effects of both depth-dependent thermal expansivity and viscosity on mantle convection have been examined with two-dimensional finite-element simulations in aspect-ratio ten boxes. Surface Rayleigh numbers between 107 6 × considered. properties, acting singly or concert, are to produce large-scale circulations a few major upwellings. interior the is cooled by many cold instabilities, which slowed down eventually swept about circulation. temperature can be influenced trade-off properties internal heating. For chondritic abundance internal-heating expansivity, increase across no greater than factor around order keep lower adiabatic. contrasts blobs surrounding strongly reduced whereas lateral differences hot upwelling ambient significant, over several hundred degrees. Depth-dependent also encourage formation stronger mean-flow upper mantle, may important for promoting long-term polar motions.