Migmatites with evidence for low pressure metamorphism and partial melting occur adjacent to the Alvand Plutonic Complex in the Hamedan region of Iran. They show stromatic, schollen, diktyonitic and massive structure. Sillimanite/andalusite/(kyanite)-garnet-and cordierite-K-feldspar-andalusite-spinel-bearing migmatites are the most common rock types. Some of the granitic intrusions contain xenocrysts which resemble the porphyroblasts of nearby migmatites (e.g. sillimanite, andalusite, cordierite and garnet). Although migmatitic rocks of the region are located near the granitic intrusions, the degree of partial melting is not related to intrusions and is irregular. It appears that partial melting and migmatization pre-date the intrusion of major granitic bodies in the region. Leucosomes in stromatic migmatites are commonly parallel to bedding planes and are mostly formed by metamorphic segregation and/or in situ partial melting (showing mafic selvedges, pinch and swell structures). The melt fraction and migmatite type depend on the chemical composition of parent rocks and the distribution of high strain zones. The formation of thin leucosomes in the stromatic migmatites was controlled by short-range melt movement along the grain boundaries. Melt-rich layers are constrained by pre-existing compositional layering and foliation. Peak metamorphic conditions of ~650 °C and ~300 MPa are consistent with the observed mineral assemblages and the presence of melt in the investigated migmatites.Key words: Iran, Sanandaj-Sirjan, Hamedan, anatexis, granite, migmatite.new data pertaining to the petrogenesis of migmatites (especially of stromatic migmatites) near to the Alvand Plutonic Complex in the Hamedan region.
Geological settingThe study area is a part of the so-called Sanandaj-Sirjan Zone or Zagros Imbricate Zone of the Zagros Orogen (according to Alavi 1994Alavi , 2004. This zone comprises a metamorphic belt of low-to high-grade regional and contact metamorphic rocks that have been intruded by mafic, intermediate and felsic plutonic bodies (Fig. 1). Major metamorphic and magmatic events of the Sanandaj-Sirjan Metamorphic Belt (SSMB) occurred during the Mesozoic Era (e.g. Baharifar 1997Baharifar , 2004Sepahi 1999;Rashidnejad-Omran et al. 2002;Sheikholeslami et al. 2003;Sepahi et al. 2004;Ahmadi-Khalaji et al. 2007). Major granitic plutons of the SSMB have been atributed to the Mesozoic-Tertiary magmatism (~200 to ~40 Ma; e.g. Valizadeh & Cantagrel 1975;Masoudi 1997;Baharifar 2004;Ahmadi-Khalaji et al. 2007;Arvin et al. 2007). These events have been related to the subduction of the Neo-Tethys and later collisional events (e.g. Baharifar 1997Baharifar , 2004Sepahi 1999 andSepahi et al. 2004).
Field relations and petrography of the major plutonic and metamorphic rocksIn the Hamedan region, low-to high-grade, regional and contact metamorphic rocks occur adjacent to plutonic bodies (Fig. 2). Metapelitic rocks are the most abundant, compris-
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