Viscosity of peridotite liquid

The Newtonian viscosity of molten peridotite has been determined experimentally at superliquidus and supercooled conditions. The high-temperature determinations were obtained using a concentric cylinder technique employing constant high-speed deformation. The low-temperature determinations have been obtained from the analysis of the glass transition in scanning calorimetric traces and conversion via published shift factors into viscosity data. These latter measurements were made possible by the experimental synthesis of peridotite glass using a splat-quenching device. Despite having an extremely low viscosity near its liquidus temperature (10^-1 Pa s), peridotite exhibits a very high glass transition temperature, 1006 to 1018 K (depending on scanning rates), at which viscosities of 10^10.13 to 10^10.73Pa s were calculated. These data show that the viscosity of molten peridotite has an extremely non-Arrhenian temperature dependence and allow its viscosity to be predicted at the even higher temperatures expected to exist where molten peridotite is or was present in the mantle.