Diffusion Creep of Diopside

Subhajit Ghosh (1, 2, 3) , S. Koizumi (3) , T. Hiraga (3)

1 ISTO - Institut des Sciences de la Terre d'Orléans - UMR7327
2 Géodynamique - UMR7327
3 UTokyo - The University of Tokyo

We have conducted uniaxial compression experiments on fine-grained diopside with either 4 or 10 vol% forsterite and 10 vol% anorthite. We changed the average grain size in the diopside with forsterite aggregate from 0.43 to 4.07µm to reveal the grain size sensitivity of the creep rate. Mechanical data were obtained at a stepped load for a temperature range of 1050°C–1170°C. The observed strain rates are best explained by stress and grain size exponent values of 1 and 2, respectively, and activation energy of 720kJ/mol, which indicates lattice diffusion creep. Anorthite bearing aggregate is 3 times weaker than forsterite-bearing aggregate, probably due to the presence of aluminum. We have compared previously reported diffusion creep rates of diopside in nondimensional stress and strain-rate space, constructed based on our diffusion creep law. It demonstrates that all the earlier mechanical data are well summarized by our diffusion creep flow law

Domaines: Planète et Univers [physics]

Subhajit Ghosh, S. Koizumi, T. Hiraga. Diffusion Creep of Diopside. Journal of Geophysical Research : Solid Earth, 2021, 126 (1), pp.e2020JB019855. ⟨10.1029/2020JB019855⟩. ⟨insu-03186366⟩