Stability of zircon in dunite at 1400-1550A°C

The results of experimental studies of interaction between zircon crystals and dunite at 1400-1550A degrees C are given. At 1400A degrees C no interaction of zircon with dunite takes place. At higher temperatures zircon interacts with olivine forming eutectoid mixture of baddeleyite and pyroxene grains. Change of free energy at interaction is close to zero and process is reversible. At 1550A degrees C partial melting of dunite occurs, but character of interaction with dunite remains the same. Experiments results verify phase relationships in liquidus area at diagram. The obtained results allow explaining the ancient age of zircons in ultrabasite of folded areas.