[M-GI35] Computational sciences on the universe, galaxies, stars, planets, and their environments

[MGI35-P05] Three-dimensional modeling of magma generation, migration, concentration, and solidification in a convecting solid mantle

*Takatoshi Yanagisawa¹, Masanori Kameyama², Masaki Ogawa³ (1.Research Institute for Marine Geodynamics, Japan Agency for Marine-Earth Science and Technology, 2.Geodynamics Research Center, Ehime University, 3.Graduate School of Arts and Sciences, University of Tokyo)

Keywords:mantle convection, magmatism, three-dimensional modeling

Magmatism in rocky mantle of terrestrial planets is one of the most important factors for surface tectonics and volcanic activities. It is also an essential mechanism for the evolution of internal structure of planets. Melting in mantle induces differentiation of the composition resulting a formation of crust. We treat a series of process of magma ascent in a numerical simulation including magma generation, migration, concentration, and re-solidification in a simplified setting. The background is a slowly convecting mantle of solid phase. Melting and solidification, that is phase changes of the material, occur depending on the thermodynamics. We set an idealized solidus curve depending on the depth; the generated melt is slightly lighter than the solid material. In the model, migration of melt is modeled as a permeable flow driven by the density difference. When a relative motion between the melt and solid occurs, the porosity of mantle rock changes and the permeability is reduced or increased. There is also a feedback process from the existence of melt to the convective motion of the solid mantle. The important parameters in this modeling are Rayleigh number for solid mantle convection and non-dimensional permeability relating to magma migration. We succeeded in the three-dimensional treatment of this calculation in horizontally wide geometries. Though this model does not include such as crust and lithospheric plate at present, it will help quantifying spatial scales of magmatic activities and time scales of structural evolution in rocky mantle.