Study of protolith, thermobarometry and formation condition of garnet cordierite hornfelses from south of the Serkan area (SW of the Hamedan Province)


1 Geology Department, Faculty of Science, Bu-Ali Sina University, Hamedan

2 Geology Department, Faculty of Earth Sciences, Shahid Chamran University of Ahvaz, Ahvaz


The Alvand batholith contact aureole hornfelses in south of the Serkan area (NW Hamedan province) contain metamorphic assemblage cordierite + garnet + biotite + plagioclase + K-feldspar. Whole rock compositions of the hornfelses show that they formed by metamorphism of a pelitic protolith (with some CaCO3 impurities) that originated from weathering of felsic to intermediate igneous rocks. Electron microprobe analyses indicate that the cordierites and biotites are of Fe-rich associations, the garnets are rich in almandine and spessartine and the plagioclases are oligoclase. Thermobarometry calculations using the in-equilibrium minerals obtained 550 to 620 oC T and >3 kbar P for these rocks. Also, the calculated pseudosections for average composition of these rocks demonstrate that the cordierite + garnet assemblages occurred due to high Mn and Ca contents of the garnets, high Mg contents of the cordierite and probably during uplifts during intrusion of the igneous bodies. Moreover, investigation of variations in fluids during metamorphism show that stability of the cordierite + garnet assemblages needed some CO2 contribution.


Acocella, V., 2000. Space accommodation by roof lifting during pluton emplacement at Amiata (Italy). Terra Nova 12,149-55
Alavi, M., 1994. Tectonics of the Zagros orogenic belt of Iran: new data and interpretations. Tectonophysics 229(3-4), 211-38.
Amidi, M., Majidi, B., 1977. Geology map of Hamedan (1: 250,000). Geological Survey of Iran, Tehran.
Azizi, H., Nouri, F., Stern, R.J., Azizi, M., Lucci, F., Asahara, Y., Zarinkoub, M.H., Chung, S.L., 2018. New evidence for Jurassic continental rifting in the northern Sanandaj Sirjan Zone, western Iran: The Ghalaylan seamount, southwest Ghorveh: International Geology Review 62, 1335 – 1657.
Baharifar, A., Moinevaziri, H., Bellon, H., Piqué, A., 2004. The crystalline complexes of Hamadan (Sanandaj–Sirjan zone, western Iran): metasedimentary Mesozoic sequences affected by late cretaceous tectono-metamorphic and plutonic events. CR Geoscience 336, 1443–1452.
Berberian, M., King G., 1981. Towards a paleogeography and tectonic evolution of Iran: Reply. Canadian Journal of Earth Sciences 18(11), 1764.
Bucher, K., Grapes, R., 2011. Petrogenesis of Metamorphic Rocks, Springer, p.428.
Chegini, A., Sorbi, A., Arian, M., 2015. Active Tectonics of Hamedan Area, West Iran. International Journal of Geography and Geology 4(6), 109-28.
Chen, M., Sun, M., Cai, K., Buslov, M., Zhao, G., Rubanova, E.S., 2014. Geochemical study of the Cambrian-Ordovician meta-sedimentary rocks from the northern altai-mongolian terrane, northwestern Central Asian Orogenic Belt: Implications on the provenance and tectonic setting. Journal of Asian Earth Sciences 96, 69-83.
Cisterna, C.,E., Altenberger, U., Mon, R., Günter, C., Gutiérrez, A., 2017. The metamorphic basement of the southern Sierra de Aconquija, Eastern Sierras Pampeanas: Provenance and tectonic setting of a Neoproterozoic back-arc basin. Journal of South American Earth Sciences 82, 292-310.
Connolly, J.A.D., 2005. Computation of phase equilibria by linear programming: A tool for geodynamic modeling and its applicationto subduction zone decarbonation. Earth and Planetary Science Letters 236, 524–541.
Deer, W.A., Howie R.A., Zussman J., 1992. An Introduction to the Rock Forming Minerals, Longman, London, p. 528.
Fergusson, C., Nutman, A.P., Mohajjel, M., Bennet, V.C. 2016. The Sanandaj–Sirjan Zone in the Neo-Tethyan suture, western Iran: Zircon U–Pb evidence of late Palaeozoic rifting of northern Gondwanaand mid-Jurassic orogenesis. Gondwana Research 40, 43-57.
García-Casco, A., Torres-Roldán, R.L., 1999. Natural metastable reactions involving garnet, staurolite and cordierite: implications for petrogenetic grids and the extensional collapse of the Betic-Rif Belt. Contributions to Mineralogy and Petrology 136, 131-53.
Garrels, R.M., McKenzie, F.T., 1971. Evolution of sedimentary rocks. Norton, New York, p. 397.
Ghasemi, A., Talbot, C.J., 2006. A new tectonic scenario for the Sanandaj–Sirjan Zone (Iran). Journal of Asian Earth Sciences 26, 683-93.
Grew, E.S., Locock, A.J., Mills, S.J., Galuskina, I.O., Galuskin, E.V., Hålenius, U., 2013. Nomenclature of the garnet supergroup. American Mineralogist 98, 785-811.
Harley, S.L., Thompson, P., Hensen, B. J., Buick, I. S, 2001. Cordierite as a sensor of fluid conditions in high-grade metamorphism and crustal anatexis. Journal of Metamorphic Geology 20, 71-86.
Hassanzadeh, J., Wernicke, B., 2016. The Neotethyan Sanadaj–Sirjan zone of Iran as an archetype for passive margin–arc transitions. Tectonics 35, 586–621.
Herron, M.M., 1988. Chemical classification of terrigenous sands and shales from core or log data. Journal of Sedimentary Petrology 58, 820-829.
Holdaway, M., Lee, S.M., 1977. Fe-Mg cordierite stability in high-grade pelitic rocks based on experimental, theoretical, and natural observations. Contributions to Mineralogy and Petrology 63, 175-98.
Holdaway, M.J., 2000. Application of new experimental and garnet Margules data to the garnet-biotite geothermometer. American Mineralogist 85, 881-892.
Kitamura, M., Yamada, H., 1987. Origin of sector trilling in cordierite in Daimonji hornfels, Kyoto, Japan. Contributions to Mineralogy and Petrology 97, 1–6.
Mahmoudi, S., Corfu, F., Masoudi, F., Mehrabi, B., Mohajjel, M., 2011. U–Pb dating and emplacement history of granitoid plutons in the northern Sanandaj–Sirjan Zone, Iran. Journal of Asian Earth Sciences 41, 238–249.
Mahmoudi, Sh., Baharifar, A., 2018. Phase equilibria and P-T-t path of metapelitic rocks in SE-Hamedan, Sanandaj-Sirjan Zone, Iran. Mineralogy and Petrology 113, 135-154.
Meres, S., 2005. Major, trace element and REE geochemistry of metamorphosed sedimentary rocks from the Malé Karpaty Mts. (Western Carpathians, Slovak Republic), Implications for sedimentary and metamorphic processes. Slovakia Geology Magazine 11, 107 – 122.
Miri, M., Sepahi, A., Aliani, F., Maanijou, M., 2016. Chemical zoning of Ca-amphiboles in amphibolites, from the Hamedan area, West Iran. Arabian Journal of Geosciences 9(13), 619.
Mohajjel, M., Fergusson, C., 2014. Jurassic to Cenozoic tectonics of the Zagros Orogen in northwestern Iran. International Geology Reviews 56, 263–287.
Mohajjel, M., Fergusson, C., Sahandi, M., 2003. Cretaceous–Tertiary convergence and continental collision, Sanandaj–Sirjan zone, western Iran. Journal of Asian Earth Sciences 21, 397-412.
Monfaredi, B., Hauzenberger, C., Neubauer, F. Schulz, B., Genser, J., Shakerardakani, F., Halama, R., 2020. Deciphering the Jurassic–Cretaceous evolution of the Hamadan metamorphic complex during Neotethys subduction, western Iran. International Journal of Earth Sciences109, 2135–2168.
Nesbitt, H., Young, G., 1984. Prediction of some weathering trends of plutonic and volcanic rocks based on thermodynamic and kinetic considerations. Geochimica et Cosmochimica Acta 48, 1523-1534.
Osberg, P.H., 1971. An equilibrium model for Buchan-type metamorphic rocks south-central Maine. American Mineralogist 56, 569-576.
Roser, B.P., Korsch, R.J., 1986. Determination of Tectonic Setting of Sandstone– Mudstone Suites Using, Content and, Ratio. Journal of Geology 94, 635–650.
Saki, A., 2017. The difference between metamorphic series in the metapelitic rocks of south and north of Alvand Batholith, Hamadan. Iranian Journal of Geology 11, 83-97.
Saki, A., Miri, M., Oberhansli, R., 2020. High temperature – low pressure metamorphism during subduction of Neo-Tethys beneath the Iranian plate: Evidence for mafic migmatite formation in the Alvand complex (western Iran). Mineralogy and Petrology 114, 539–557.
Saki, A., Moazzen, M., and Baharifar, A., 2012. Migmatite microstructures and partial melting of Hamadan metapelitic rocks, Alvand contact aureole, western Iran. International Geology Reviews 54, 1229–1240.
Scudder, C., 2018. Structure and Emplacement of the Eocene Golden Horn Batholith, North Cascades, Washington. M.Sc thesis, San José State University, San Jose, California.
Sepahi, A.A., Borzoei, K., Salami, S., 2013. Mineral chemistry and thermobarometry of plutonic, metamorphic and anatectic rocks from the Tueyserkan area (Hamedan, Iran). Geological Quarterly 57, 515-526.
Sepahi, A.A., Jafari, S.R., and Mani-Kashani, S., 2009. Low pressure migmatites from the Sanandaj-Sirjan Metamorphic Belt in the Hamedan region, Iran. Geologica Carpathica 602, 107–119.
Sepahi, A.A., Jafari, S.R., Osanai, Y., Shahbazi, H., Moazzen, M., 2019. Age, petrologic significance and provenance analysis of the Hamedan low pressure migmatites, Sanandaj-Sirjan zone, west Iran. International Geology Review 61, 1446–61.
Sepahi, A.A., Salami, S., Lentz, D., McFarlane, C., Maanijou, M., 2018. Petrography, Geochemistry and U-pb Geochronology Of Pegmatites and Aplites Associated with The Alvand Intrusive Complex in The Hamedan Region, Sanandaj-sirjan Zone, Zagros Orogen (Iran). International Journal of Earth Sciences107, 1059-1096.
Sepahi, A.A., Shahbazi, H., Siebel, W., Ranin, A., 2014. Geochronology of plutonic rocks from the Sanandaj–Sirjan zone, Iran and new zircon and titanite U–Th–Pb age for granitoids from the Marivan pluton, Geochronometria 413, 207–215.
Sepahi, A.A., Vahidpour, H., Lentz, D.R., McFarlane, C.M., Maanijou, M., Salami, S., Miri, M., Mansouri, M., Mohammadi, R., 2020. Rare sapphire-bearing syenitoid pegmatites and associated granitoids of the Hamedan region, Sanandaj–Sirjan zone, Iran: analysis of petrology, lithogeochemistry and zircon geochronology / trace element geochemistry. Geological Magazine157, 1499-1525.
Sepahi, A.A., Whitney, D.L., Baharifar, A.A., 2004. Petrogenesis of andalusite–kyanite–sillimanite veins and host rocks, Sanandaj– Sirjan metamorphic belt. Hamadan, Iran. Journal of Metamorphic Geology 22, 119-134.
Shahbazi, H., Siebel, W., Pourmoafee, M., Ghorbani, M., Sepahi, A., Shang, C., 2010. Geochemistry and U–Pb zircon geochronology of the Alvand plutonic complex in Sanandaj–Sirjan Zone (Iran): New evidence for Jurassic magmatism. Journal of Asian Earth Sciences 39(6), 668-83.
Stöcklin, J., Nabavi, M.H., 1973. Tectonic Map of Iran: Geological Survey of Iran, scale 1:2 500 000.
Taylor, S.R., McLennan, S.M., 1985. The Continental Crust: its Composition and Evolution. Blackwell, Oxford University, Oxford, p. 312.
Tracy R.J., Robinson, P., Thompson, A.B., 1976. Garnet composition and zoning in the determination of temperature and pressure of metamorphism, central Massachusetts. American Mineralogist 61, 762-75.
Whitney, D.L., Evans, B.W., 2010. Abbreviations for names of rock-forming minerals. American Mineralogists 95, 185–187.
Wu, C., Zhang, J., Ren L., 2004. Empirical Garnet–Biotite–Plagioclase–Quartz (GBPQ) Geobarometry in Medium- to High-Grade Metapelites. Journal of Petrology 45, 1907–1921.
Yang, T.N., Chen, J.L., Liang, M.J., Xin, D., Aghazadeh, M., Hou, Z.Q., Zhang, H.R., 2018. Two plutonic complexes of the Sanandaj-Sirjan magmatic-metamorphic belt record Jurassic to Early Cretaceous subduction of an old Neo-Tethys beneath the Iran microplate. Gondwana Research 62, 246-268.
Yoshinobu, A.S., Fowler, T.K., Paterson, S.R., Llambias, E., Tickyj, H., Sato, A.M., 2003. A view from the roof: magmatic stoping in the shallow crust, Chita pluton, Argentina. Journal of Structural Geology 25, 37-48.