New clinopyroxene-liquid thermobarometers for mafic, evolved, and volatile-bearing lava compositions, with applications to lavas from Tibet and the Snake River Plain, Idaho

Abstract

Our ability to calculate the depths and temperatures at which magmas partially crystallize can prove crucial as petrologists test hypotheses of magma transport and evolution. Yet whereas numerous magma transport arguments involve hydrous and SiO2-rich volcanic products, current clinopyroxene-liquid thermobarometers have been calibrated only from basaltic liquid compositions. To remedy this deficiency, new thermobarometers have been calibrated using new experiments that include hydrated (water-undersaturated) and SiO2-rich liquids ranging to 71.3 wt% SiO2. As with prior models, the new calibrations are based on jadeite crystallization and jadeite-diopside + hedenbergite exchange equilibria: