Document Type : Original Research Paper

Authors

• A. Saki ¹
• A. A. Baharifar ²

¹ Associate Professor, Department of Geology, Shahid Chamran University of Ahvaz, Ahvaz, Iran

² Assistant Professor, Department of Geology, Abhar PNU, Abhar, Iran

Abstract

Field relations and petrographical features, shows that formation of the metapelitic and carbonate rocks of Hamadan in Western Iran was poly-metamorphic. The intrusion of the Alvand Batholite (Jurassic age) into pelitic and calcareous host rocks has produced metamorphic rocks in the Cheshin area containing, sillimanite hornfels, marbles and calc-silicate rocks. Mineral assemblages in the metapelitic and calc-silicate rocks are different, peak metamorphic assemblages of these rocks respectively are garnet, biotite, staurolite, aluminosilicate minerals (kyanite/sillimanite), muscovite and quartz but calc-silicate assemblage are garnet, diopside, wollastonite epidote and amphibole, which usually take place by contact metamorphism. Using multiple equilibria, temperature (~600-630 ºC), pressure (~2-4 kbar), and fluid composition (XCO₂ as low as 0.17) have been calculated for the formation of the calc-silicated rocks. The results show good agreement with those from other meta-pelitic rocks.  P-T results indicate that contact metamorphism conditions occur in pyroxene hornfels facies in this part of the Hamadan crust.

20.1001.1.10237429.1392.22.87.5.1