Petrology, Geochemistry and tectono-magmatic setting of Estand granitoid, southwest of Birjand, East of Lut block

The Estand granitoid pluton is located in the southwest of Birjand, in the eastern edge of the Lut block, It is located near the Neh Western fault, and branches of this fault have cut off this pluton and the surrounding rocks. Its lithological composition includes: tonalite, granodiorite and granite (monzo-syenogranite) and its minerals are quartz, plagioclase, microcline, orthose, biotite, muscovite and garnet. The Estand granitoid is high-potassium calc-alkaline, peraluminus and S- type, which is derived from a poor of clay metagreywacke origin. The uniform and coordinated trend of the samples in the rare earth elements and spider diagrams normalized to the primary mantle and chondrite shows the genetic relationship and they are co-genetic with each other and the enrichment in LREE, Th, U, K, La and Pb elements and the depletion in HREE, Nb, Ti, Sr and P reflect the role of continental crust and crust-derived melt. The rocks of this pluton have formed in a post collisional setting, in a normal continental collision arc, due to the melting process in the upper crust. The geochemical evidence shows that this pluton is obtained only from crustal component without intervention of the mantle, by biotite dehydration. In addition, heat from shear zone and collision areas could play a role in melting the sediments of its source. The pressure and temperature diagrams show water pressure of ≥5 kbar and temperature of 750 to 800 °C for granitoid pluton and temperature of 830 to 850 °C for its enclave.