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Abstract: The Astaneh plutonic complex consists of a series of granitoid rocks ranging in composition from quartz-diorites to monzogranites and evolving from metaluminous to weakly peraluminous compositions. They belong to the high-K calc-alkaline series, having features of typical Andean-type cordilleran granitoids. Trace and rare-earth elements distribution patterns for the Astaneh rocks indicate a distinctive depletion in Nb, Sr, Ba, P and Ti relative to other trace elements and a greater enrichment in LILE compared to HFSE. These geochemical characteristics suggest the participation of an important recycled (sedimentary?) component in the source region of the granitoids. They have Sr initial isotopic ratios in the range 0.7078–0.7084 and negative ε Nd values of −5.39 to −6.13 for a time of generation of 170Ma. There is a genetic link between quartz-diorites and granodiorites, the dominant rock types of the Astabeh intrusion. Direct melting or fractionation from a diorite source is very unlike. It is proposed that the Astaneh parental Qtd-diorite magmas were produced by the partial melting of a mixed source, dominantly composed of amphibolites and sediments, that was formed during subduction of Neo-Tethyan oceanic crust below the Iranian microcontinent during Middle Jurassic times. [Copyright &y& Elsevier]

The migmatites in the Boroujerd region, Western Iran are spatially associated with felsic and mafic magmatism. However, the genetic relationship between partial melting and magmatism in the region is unclear. Four metapelite migmatite samples (two melanosome and two leucosome) were selected for U-Pb zircon geochronology to determine the timing of anatexis. Major and trace element compositions of leucosome in the migmatites are consistent with being derived from biotite-breakdown partial melting of metapelites and not from the injection of granites associated with the Boroujerd igneous complex. Cores of zircon from metapelitic migmatite are inferred to be detrital in origin and yield ages of 320–250 Ma. The age of the detrital zircons is compatible with the timing of Paleozoic and Mesozoic magmatism in the Central Iranian micro-plate. The pelitic protolith of the migmatites in the Boroujerd region were probably originated from the Mesozoic continental margin of the Central Iranian microplate. Zircon rims and neoblastic grains yield ages of 220–210 Ma and 170–160 Ma. The geological significance of the older age population is unclear, but the younger population is similar to that of mafic and felsic intrusions in the area and is interpreted to record the general timing of high-temperature–low-pressure contact metamorphism and partial melting. We infer that the Middle Jurassic mafic and felsic magmatism was the principal heat source for the metamorphism and partial melting of the Boroujerd migmatites in response to the subduction of Neotethyan oceanic lithosphere. • Migmatites in the Boroujerd complex record high-temperature metamorphism. • Protoliths have maximum depositional ages of c 320–250 Ma. • The older metamorphism at c. 220 Ma was followed by partial melting at c. 170 Ma. • Jurassic mafic magmatism was the primary heat source for low-P–high-T anatexis. [ABSTRACT FROM AUTHOR]