Experimental Study of the Formation of Ba–Cr Titanates in the Fluid-Bearing Chromite–Rutile/Ilmenite System at Т = 1000–1200°С and Р = 1.8–5.0 GPa

Abstract The results of experimental study of crystallization of chromium-bearing Ba-titanates (redlegeite, lindsleyite, and hawthorneite) in the chromite–rutile/ilmenite system in the presence of the H2O–CO2–BaCO3 fluid at pressures of 1.8, 3.5, and 5.0 GPa and temperatures of 1000–1200°C, simulating the formation of these phases through metasomatism of peridotite of the upper mantle, are reported. Experiments showed the formation of Ba–Cr-titanates in the entire pressure range studied and the possibility of joint crystallization of titanates. However, redledgeite is formed only in the Fe-poor chromite–rutile–H2O–CO2–BaCO3 system, whereas minerals of the magnetoplumbite group are preferably crystallized in the system with ilmenite. Lindsleyite was not detected at a pressure of 1.8 GPa. A positive dependence of the Cr content in titanates on pressure was shown. The Raman spectra of redlegeite, lindsleyite, and hawthorneite are presented.