Dynamical influences of high viscosity in the lower mantle induced by the steep melting curve of perovskite: Effects of curvature and time dependence

在请求帮助或建议时，用'in the event of...'而非'要是...就好了' #生活技巧# #职场沟通技巧# #商务英语#

Papers on Geodesy and Gravity Tectonophysics

First published: 10 August 1995

Citations: 26

Abstract

Recent experiments on the melting temperatures of perovskite have indicated a high melting temperature in the lower mantle. This suggests that a creep law with an activation enthalpy, that increases strongly with depth, should be employed for the lower mantle rheology. We have examined the dynamical consequences of employing an Arrhenius type of dependence in a Newtonian flow law under the Weertman assumption relating activation enthalpy to the variation of the melting temperature with pressure. We have employed finite element techniques to model both steady state and time-dependent flows for such type of rheology in an axisymmetric spherical- shell model. An outstanding dynamical feature from these models is the presence of a local viscosity maximum with a magnitude of around 1023Pa · s for Earthlike surface Nusselt numbers between 10 and 15. This viscosity maximum is found in the middle of the lower mantle and is a site of high deviatoric stresses between 10 and 100 MPa. For the surface Rayleigh numbers examined (104 to 105) the flows developed are not strongly time-dependent and often tend to a steady state. In spite of the presence of internal heating with chondritic strength, a few large, relatively stationary plumes are found in the lower mantle, while the rest of the lower mantle circulation is being driven by the more vigorous upper mantle flow. There are no small-scale instabilities developed in the D” layer of these models, thus suggesting that any small-scale lateral heterogeneities existing there may have chemical origins.

References

Citing Literature

网址：Dynamical influences of high viscosity in the lower mantle induced by the steep melting curve of perovskite: Effects of curvature and time dependence https://klqsh.com/news/view/154291

相关内容

Diffusion Creep in Perovskite: Implications for the Rheology of the Lower Mantle
The Role of Sclerostin in Bone Diseases
Role and mechanism of action of sclerostin in bone
Role of sclerostin in bone and cartilage and its potential as a therapeutic target in bone diseases
The role of the krone exchange rate under flexible inflation targeting
The loss of details in a fast
Who decides the interest rate in Norway?
Pubs and Restaurants of Ingram Street: 12 of the best cafes, bars and restaurants on Ingram Street right now
Monetary policy and the krone exchange rate
“One of the Finest Hotels in Texas” since 1886

随便看看