Features of Mineral and Chemical Composition of the Khamambettu Carbonatites, Tamil Nadu

Abstract

Abstract The paper presents mineralogical features and EPMA results of the Khamambettu carbonatites. The mineralogical data suggest that these rocks have been generated in magmatic and hydrothermal stages. Mineral geothermometer for carbonatite give temperatures of 790°-980°C. Fluid inclusion measurements in monazite (hydrothermal stage) give temperatures of 220°-290°C. One of the features of the carbonatites is high content of magnesia that is defined by the presence of dolomite, olivine, spinel, phlogopite, Mg-rich ilmenite. Chloritization, serpentinization, amphibolization, silicification processes and occurrence of barite, monazite-(Ce), strontianite, celestine are related to hydrothermal stage. Hydrothermal minerals at the Khamambettu were formed by recrystallization of primary carbonatite minerals in the presence of Ba, (SO4)2−, REE and Si carried in solution by the hydrothermal fluid.