A SEMI-QUANTITATIVE TECHNIQUE FOR DETERMINATION OF CO2 IN CORDIERITE BY RAMAN SPECTROSCOPY IN THIN SECTIONS

Abstract

Confocal micro-Raman spectroscopic measurements at high spatial resolution of about 5 μm3 were performed to determine the CO2 contents of natural cordierite. Nine cordierite single-crystals with known CO2 concentrations, previously determined by colorimetric titration, were studied to obtain a calibration curve for this method. Measurements were also performed to quantify the CO2 content of cordierite porphyroblasts in a thin section of a granulite-facies metapelite from Kösseldorf, Sauwald Area, Southern Bohemian Massif, Upper Austria. Fifteen points along a traverse through a large (560 μm) single crystal revealed low CO2 contents of 0.14 ± 0.11 wt. % CO2. These results provide some constraints on the activity of CO2 [a(CO2)] during granulite-facies metamorphism, only if fluid-saturated conditions prevailed or independent H2O measurements were made. © 2006 E. Schweizerbart'sche Verlagsbuchhandlung.