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.