Role of iron content on serpentinite dehydration depth in subduction zones: Experiments and thermodynamic modeling

摘要

A series of dehydration experiments in the piston-cylinder apparatus was carried out at 2 GPa and 550-850 degrees C on a natural antigorite sample mixed with 5 wt.% of magnetite. Chemical analyses of experimental products show a progressive decrease of the Mg# in antigorite and dinopyroxene between 550 and 675 degrees C, whereas the Mg# of olivine increases. The observed behavior of Mg# signifies Fe-Mg exchange between coexisting minerals. At higher temperatures, between 700 and 850 degrees C, compositions remain stable for all minerals in experimental assemblages.