Rheological properties of mantle rocks using high-strain torsion experiments

Mantle deformation is closely related to plate motion, earthquakes, and volcanic activities. In previous experimental studies, the rheological properties of the mantle rocks have been determined based on assumptions that the mantle rocks are composed of single-phase crystal aggregates with a homogeneous chemical composition, and the mechanical data and rock microstructure reach a steady-state even at small strain. However, it is obvious that these assumptions oversimplify the complexity of natural rocks. To overcome such limitations, the author conducted various types of deformation experiments to investigate the rheological properties of rocks by taking into account the secondary mineral phases, diŠerent iron content of olivine, and diŠerent strain. The obtained results allow us to understand the mantle ‰ow under more realistic conditions. In this paper, I would like to introduce the recent results of high-strain torsion experiments using a Patterson-type gas-medium apparatus.