ISOTOPIC AND THERMODYNAMIC MODEL OF THE M URUNTAU SKARN SERIES

The combination of thermodynamic modeling and isotopic studies was app lied for the investigation of Ca-metasomatite (skarn) formation of the Muruntau ore field. Step reactor method was used and modeling columns were constructed, the latter corresponding to different modes of the metasomatic process as following: metamorphic transformation of the ca rbonate-terrigeneous rocks, the metasomatosis with different combinati on of fluid source and wall rocks. It was shown that the intensive Ca- metasomatosis is provided by the decompression, the latter being respo nsible for fluid alkalinity increase and formation of typomorphic skar n minerals such as diopside, grossular, tremolite etc. The isotopic Sr composition of skarn minerals and terrigeneous wall rocks were found to be similar indicating the wall rocks as the source of fluids. The s tudy outlines the role of tectonic deformations as a starting mechanis m of the metasomatic processes.