Abstract
Geobarometers used at pressures corresponding to the crust and upper mantle conditions are summarized. Geobarometers have not been established at pressures above 5 GPa. Pressure dependency of concentration of pyroxene molecule in majorite, i.e. “majorite geobarometer”, may be a candidate for a geobarometer in the pressure range above 5 GPa. Responses of the two pyroxene geothermometer and orthopyroxene-garnet geobarometer to the geologically plausible changes in tem-perature and pressure in the mantle were evaluated on the basis of the diffusion data of cations available. The basic assumption of chemical equilibrium in garnet peridotite xenolith is examined critically.
