COMPARATIVE STABLE ISOTOPES STUDY OF THE MAGNESITE DEPOSITS OF GREECE

The magnesite deposits of North Evia, Lesvos and Chalkidiki, which are hosted by Alpine type ultramafic rocks, have been studied from an isotopie point of view and are compared with similar magnesite deposits occurring in other countries of central-southeastern Europe and Turkey. Magnesites from N. Evia, Lesvos and Chalkidiki have similar isotopie compositions. They have 513CPDB values ranging from -8.6 %o to -14.8 %o and 518OSMOW values ranging from 24.0 %oto 30.1 %o, which indicate a rather similar formation process for all three areas. The studied Greek magnesite deposits have similar isotopie compositions with vein and stockwork type magnesite deposits from: Turkey (Koyakci Tepe, vein and stockwork types; Helvacibaba, stockwork type), Poland (vein type), and Former Yugoslavia (vein type). There is strong isotopie evidence that meteoric water is involved in the formation of the stockwork and vein type magnesite deposits of all four countries, including Greece. There is also isotopie evidence for the organic origin of carbon participating in the carbonates (magnesites) of these deposits