Étude expérimentale de la distribution de l'aluminium entre bain silicaté basique et spinelle chromifère. Implications pétrogénétiques : teneur en chrome des spinelles

Abstract

The partitioning of aluminium between silicate melt (olivine tholeiite) and chromian spinel was studied experimentally. Runs were carried out at temperatures of 1 180˗1 300 °C and oxygen fugacities of 10⁻⁷˗10⁻⁹ atmosphere, at one atmosphere total pressure. The Al₂O₃ content of spinel is related to the Al₂O₃ content of melt as follows : (Al₂O₃)[sp] = 0.035 (Al₂O₃)[liq], where Al₂O₃ is expressed in weight %. Thus there is a positive correlation between the partition coefficient D = (Al₂O₃)[sp]/(Al₂O₃)[liq] and the Al₂O₃ content of the melt. Temperature and oxygen fugacity have only a minor effect on D. Consequently, within the limits of experimental conditions, the chromium content of spinel increases as the Al₂O₃ content of the melt decreases.