A new generation Griggs apparatus with active acoustic monitoring

High pressure and temperature experiments are necessary to understand geological processes at deep earth conditions. Here, we present a new generation Griggs-type apparatus, designed to perform deformation experiments at P-T conditions of the lower crust and upper mantle, i.e. up to 5 GPa and 1000 °C. We first detail the experimental design, set-up and procedure, as well as the calibration protocol of the apparatus. The main innovation of this new set-up is the development of an active acoustic monitoring pulse-transmission technique, which enables us to monitor the evolution of P-wave elastic velocities, at 5 MHz, contemporaneously with deformation. This may provide information on the evolution of the microstructure, in particular when mineralogical (metamorphic) reactions are taking place. For instance, P-wave velocity variations across the α → β quartz transition are recorded for the first time within a Griggs apparatus, at 0.5 and 0.8 GPa. This new set-up opens up important perspectives for the study of the complex couplings that may take place between mineral reactions and deformation under in lithospheric stress and temperature conditions. •A new generation high pressure and temperature solid medium rock deformation apparatus is presented.•Experimental set-up, protocol and calibration procedures are carefully presented.•Elastic P-wave velocities can be measured during deformation.•Evolution of P-wave velocities are measured during α → β quartz transition at 0.5 and 0.8GPa.