Development and applications of micro-scale isotopic analyses for metamorphic dolomites

A small-scale analytical technique for carbon and oxygen isotopic analyses of dolomite, siderite and magnesite was developed using a batch method. Carbonate samples were reacted with conc-phosphoric acid at 100℃ in vacuo. Using this batch method, standard calcite and dolomite samples were examined to check the minimum size of samples required. CO_2,gas greater than 10μl can be precisely measured with the conventional certainty. For smaller samples, isotopic results are affected by some contaminations evolved during reaction at 100℃ with phosphoric acid. Metamorphic calcite and dolomite collected from the Kasuga contact aureole, Gifu Pref. were examined using the small-scale analyses. Within a hand specimen size, a large oxygen isotopic heterogeneity up to 6‰ Was observed.publishe