LA-ICP-MS zircon U-Pb geochronology on migmatites from the Boroujerd region, Sanandaj-Sirjan zone, Zagros Orogen, Iran: provenance analysis and metamorphic age

A narrow zone of migmatitic rocks forms part of the metamorphic complex associated with the Boroujerd plutonic complex in the north-western part of the Sanandaj-Sirjan zone, Iran. It includes stromatic, dyktionitic, schollen and massive migmatite, metatexites and diatexites. Leucosome (alkali-feldspar granitic and trondhjemitic) and mesosome are well developed, melanosome less so. Detrital zircon cores from one mesosome range in age from ∼ 2540 to 210 Ma, with a major sub-population at ∼ 250 Ma. The detrital zircon is probably derived from igneous bodies from the Iranian micro-plate (southern Eurasia) and possibly Pan-African and Arabian-Nubian basement no longer exposed. Metamorphism at 170–160 Ma recorded by thin metamorphic zircon rims is similar in age to the adjacent plutonic rocks from the Boroujerd area (172–169 Ma), both occurring in a middle Jurassic continental arc setting.