Geochemistry and zircon geochronology of the Permian A-type Hasanrobat granite, Sanandaj–Sirjan belt: A new record of the Gondwana break-up in Iran (original) (raw)

The Sanandaj-Sirjan metamorphic-plutonic Belt (SSB) in west central Iran is a polyphase metamorphic terrain composed of dominantly greenschist-grade metasedimentary and metavolcanic rocks, and felsic to mafic plutons, of Neoproterozoic-Phanerozoic ages. The Hasanrobat granite in central SSB occurs as a single pluton, ~20 km 2 surface area, with relatively consistent mineralogy and chemistry. Quartz, alkali feldspars (microcline and perthite), sodic plagioclases and biotite are the main constituents, commonly associated with minor amphibole. Accessory phases include zircon, allanite, apatite, and magnetite. The country rocks are Upper Carboniferous-Lower Permian sandstones and dolomitic limestones. Scattered patches of skarn-type assemblages dominated by tremolite and talc occur in the dolomitic limestones, and sandstones are recrystallized to a coarse-grained quartzite at contact with the granite. The granite is metaluminous to slightly peraluminous, and is distinguished by high FeO t /MgO ratios, typical of ferroan (A-type) granites. The Atype affinity is also reflected by high Na 2 O+K 2 O, high Ga/Al ratios, high contents of large ion lithophile elements (LILE), high field strength elements (HFSE) and rare earth elements (REE), as well as low contents of Sr, and distinct negative Eu anomalies. The biotites are aluminous, Fe-rich, and plot near the siderophyllite corner in the quadrilateral biotite diagram. They are further distinguished by high fluorine contents (0.61 to 1.33 wt %).