ISOTOPIC THERMOMETRY OF SODALITE-BEARING MINERAL ASSOCIATIONS

Abstract

This publication is a logical continuation of our earlier isotopic studies of sodalite as a promising tool for the evaluation of temperatures and fluid regimes of mineral-forming processes [1]. The first data on the intrastructural oxygen isotopic distribution in synthetic sulfate-sodalite (nosean) Na8Al6Si6O24SO4 have demonstrated the possibility of using this mineral as a monomineralic isotopic geothermometer. Further exploring this avenue, we conducted a study of the infrastructural oxygen isotopic effects in Cl-sodalite and minerals coexisting with it in sodalitebearing mineral assemblages. The first task of our research was to determine the temperature dependence of the fractionation factor ∆18O in the Cl-sodalite–H2O system with the aim of evaluating the temperatures and nature of aqueous fluids.