POSSIBILITIES OF DETERMINATION OF ALTERATION DEGREE OF ROCKS BY THERMOGRAVIMETRY

Rhyolite-rhyodacite tuff samples were analysed by X-ray powder diffraction, ICP-OES and thermogravimetric (TG) methods to determine mineral and major element composition as well as different types of bound water, respectively. Similarly to CIA values, some TG parameters (H2O[I] - water released up to ca. 200-220 degrees C; H2O[III] - water loss above 500-550 degrees C and H2O[I+III]) show positive correlation to the amount of secondary minerals. Moreover, these parameters are in close positive correlation to CIA values. Our results suggest that TG determination of different types of bound water may serve as a useful tool for estimation and characterisation of alteration degree of rocks.