Zircon U–Pb ages and petrogenesis of the middle Eocene Aliabad Daman pluton, Northeast Iran: implications for magmatic activity along the Doruneh fault zone

The Aliabad Daman pluton is exposed along the Doruneh fault zone of the southern edge of the Sabzevar zone, northeast Iran. This intrusive body consists of alkali feldspar granite, syenogranite, and monzogranite. U–Pb age dating results demonstrate that the magmas crystallized 45–40 Ma ago in the middle Eocene (Lutetian to Bartonian). Whole-rock samples show SiO 2 ranging between 75.4 and 77.0 wt.%, variable fractionation between light and heavy rare earth elements (REE) (La N /Yb N = 11–22) with negative Eu anomalies Eu/Eu* (0.1–0.4), depletion of heavy REE, enrichment of large ion lithophile elements (LILE), and plot in the metaluminous to peraluminous, and high-K calc-alkaline fields. The major and trace element characteristics of the Aliabad Daman pluton bear the imprints of the partial melting process. The presence of inherited zircon and the combination of the new results with previous studies suggest that the magma of the Aliabad Daman pluton was derived from a continental crustal source and an enriched mantle source. Tectonic activities such as the shortening and the thickening of the continental crust, delamination of the lower crust and the lithospheric mantle, heating by upwelling asthenosphere, and tectonic activities along the Doruneh fault zone on the southern edge of the Sabzevar zone as well as the extensional collapse of the crust played important roles in the generation and emplacement of the Aliabad Daman pluton.