Thermal metamorphism of the mantle peridotites from Paleozoic accretionary prism by Eocene pluton (NE of Anarak, Kal-e-Kafi area, Central Iran)

The Eocene pluton intrudes the Paleozoic accretionary wedge in the Kal-e-Kafi area (NE of Anarak, Isfahan province, Central Iran). Metaperidotites of this Paleotethys-related accretionary prism consist of metalherzolite, metaharzburgite and metadunite and are associated with the listwaenites and metasediments (schist and marble).
Rock-forming minerals of the Kal-e-Kafi metaperidotites are olivine (forsterite and chrysolite, Mg# =0.86-0.92 with CaO < 0.02 wt%), orthopyroxene (enstatite, Mg# =0.84-0.86), clinopyroxene (Mg# =0.90-0.94, Al2O3 0.03-2.08 wt%), tremolite, magnesio-hornblende, anthophyllite, serpentine, talc, chlorite, chromian spinel (Cr# =0.58-0.72), magnetite and plagioclase. All these minerals are metamorphic products and are not relicts of the primary igneous mineralogy, except the inner parts of Cr-spinels. Chemical composition of the core of Cr-spinel crystals reveal that the protolith of the studied rocks were mantle peridotites which belong to the depleted and moderately depleted peridotite series. The field relationships, petrography evidences, chemical characteristics of minerals and results of the thermobarometry calculations, show that the peridotites in the Kal-e-Kafi area have suffered a regional metamorphism in P-T condition of greenschist facies during the Paleozoic, intrusion of the Kal-e-Kafi pluton, caused a progressive contact metamorphism at 630 to 750 ? under a pressure less than 1 kbar (pyroxene hornfels facies) during the Eocene.