[M-IS12] Geophysical fluid dynamics-Transfield approach to geoscience

[MIS12-P01] 2-D cylindrical mantle convection simulations on tectonic plates with stress-history-dependent rheology model

*Hiroki Taito¹, Masanori Kameyama² (1.Graduate School of Science and Engineering, Ehime University, 2.Geodynamics Research Center, Ehime University)

Keywords:stress-history-dependent rheology, mantle convection, plate tectonics

Reproducing plate tectonics is one of the most important goals of numerical simulations on mantle convection. In this study, we developed a numerical model of thermal convection of the Earth’s mantle in a 2-D cylindrical geometry making use of the stress-history-dependent rheology (Ogawa, 2003; Miyagoshi et al., 2020), which enables us to distinguish the stiff, mechanically strong plate interior and soft, highly deformable boundaries on the lithosphere. In a series of preliminary calculations we obtained the cases where the nature of highly viscous lithosphere of cold fluid is quite similar to that of the Earth’s plates; the lithosphere is divided into three or four pieces of surface plates each of which rigidly moves, and the surface heat flow of plates begins decreasing at divergent-plate-margin (ridge) in accordance with the half-space cooling model. By a careful comparison of our results with the earlier ones using 2-D Cartesian geometry (Ogawa, 2003), we also found that the cold lithosphere becomes thicker owing to an enhanced cooling by the effect of spherical geometry, which in turn affects the stress levels generated in the lithosphere. This may further imply that the condition for reproducing plate- like behavior in the 2-D or 3-D spherical mantle is slightly different from that estimated earlier by the Cartesian models.