This chapter uses numerical models to investigate the dynamics of slabs subducted in the lower mantle in dependence of three important factors that strongly affect their behavior, namely the viscosity contrast between lower and upper mantle, the two major phase transitions at 410- and 660-km depth, and, for the first time, and the pressure and temperature dependence of the coefficients of thermal expansion and conduction. It presents subduction simulations that include pressure-, temperature-, and phase-dependent thermal expansivity and conductivity, and demonstrates that these parameters exert a dramatic effect on the dynamics of lower-mantle slabs. The coefficients of thermal expansion and conduction are the two key thermodynamic parameters of the mantle that control the way heat is transported in the interior by advection and diffusion. The chapter suggests that global-scale subduction models should routinely account for the pressure and temperature variations of these two parameters.
|Original language||English (US)|
|Title of host publication||Subduction Dynamics|
|Subtitle of host publication||From Mantle Flow to Mega Disasters|
|Number of pages||19|
|State||Published - Sep 26 2015|
Bibliographical notePublisher Copyright:
© 2016 American Geophysical Union. All rights reserved.
- Constant thermal expansivity
- Lower-mantle slabs
- Subduction simulations
- Thermal conduction
- Variable thermal expansivity