ORTHOPYROXENE-GARNET GEOTHERMOMETER. EXPERIMENTS AND THEORETICAL EVALUATION OF THE DATA BASE

Abstract

Control experiments were run at 700°C and 30 kb on a UTF-40 in silver-palladium ampoules. The starting materials were natural amphibole and garnet, as well as mixtures of oxides, oxalates, hydroxides and NaAlO2. Equilibrium phase compositions were determined with the microprobe by the earlier developed method of tracing the evolution of compositional heterogeneities in minerals during the experiment. Examples of the orthopyroxene-garnet equilibrium are shown and the experimental results are presented. They are processed in thermodynamic terms together with the published experimental data base on the orthopyroxene-garnet equilibrium. Study results are discussed.