Viscoplastic Rheology of ??Quartz Investigated by Nanoindentation

Quartz is an abundant mineral in Earth's crust whose mechanical behavior plays a significant role the deformation of continental lithosphere. However, viscoplastic rheology quartz difficult to measure experimentally at low temperatures without high confining pressures due tendency (and other geologic materials) fracture under these conditions. Instrumented nanoindentation experiments inhibit cracking even ambient conditions, by imposing locally mean stress, allowing for measurement hard materials over wide range temperatures. Here we indentation hardness four synthetic specimens and one natural specimen with varying water contents temperature 23°C 500°C. Yield which calculated from but model dependent, fit constitutive flow law low-temperature plasticity estimate athermal Peierls stress quartz. Below 500°C, yield stresses presented here are lower than those obtained extrapolating constrained higher irrespective applied model. Indentation depend weakly on crystallographic orientation show no dependence content.