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The Early Miocene Taşkapı-Mecitli granitoid that is located in the northern section of the Eastern Anatolia Collision Zone has typical I-type, metaluminous and calk-alkaline characteristics. It also contains mafic microgranular / magmatic enclaves (MMEs). New Ar-Ar dating results show that the age of the Taşkapı-Mecitli granitoid is ∼23 Ma and it crystallised in the Early Miocene, in contrast to its previously known Cretaceous age. Identical crystallisation ages (∼23 Ma), similar mineral assemblages and geochemical compositions, and indistinguishable isotopic compositions of MMEs and host rocks imply that the MMEs are most consistent with a cumulate origin formed at earlier stages of the same magmatic system that produced the Taşkapı-Mecitli granitoid. MELTS modelling suggests that magma of the Taşkapı-Mecitli granitoid was the result of fractionation under a crustal pressure of 4 kbar, with a H 2 O content of 1.5%. EC-AFC model calculation reveals that the Taşkapı-Mecitli granitoid includes from 0.5% to 2% crustal assimilation rates. These rates indicate that crustal contamination can be negligible when compared to fractional crystallisation in the evolution of the magma beneath the Taşkapı-Mecitli granitoid. The partial melting model calculations and MORB-normalised trace element concentrations of the least evolved samples of the Taşkapı-Mecitli granitoid are consistent with those of mafic melts obtained from partial melting of interacting mantle- lower crust with a melting degree of 18%. The age (23 Ma) of the post- or syn-collisional Taşkapı-Mecitli granitoid suggests that the collision between Arabian and Eurasian plates could be before/around ∼23 Ma (Late Oligocene to Early Miocene). [ABSTRACT FROM AUTHOR]

The Eastern Anatolian region provides a good example for collision–related volcanic activity. This activity started during the Middle Miocene and continued through the Pliocene and Quaternary. The new K − Ar ages reveal that the post–collisional Pliocene Timar basalts located in the East Anatolian Accretionary Complex (EAAC) erupted between 4.72 (Zanclean) and 3.29–2.93 Ma (Piacenzian). The Pliocene Timar basalts consist of plagioclase, clinopyroxene (augite), and olivine minerals and have glomeroporphyritic, intergranular, and ophitic textures. They display enrichment in light rare earth elements (LREEs) with (La/Yb) N values that range between 3.19 and 6.66 to 21.63–5.61. 87Sr/86Sr(i) and 143Nd/144Nd(i) isotopic ratios of the Timar basalts are 0.70599–0.70436 and 0.51277–0.51259, respectively. The εNd(t) values of these rocks range between 1.0116 and 1.0121. 87Sr/86Sr (i) and Nd(t) contents indicate crustal contamination during the emplacement of the Timar basalts. According to the Energy Constrained–Assimilation Fractional Crystallization (EC–AFC) model, this contamination rate is between ~1.4 and 4.4%. The melting model shows that the least evolved samples of the Timar basalts were formed by ~0.1–2% partial melting of the lherzolitic source. Primitive melts that constituent Timar basalts were occurred with partial melting of a magma source that has predominantly spinel bearing mineralogy. All data indicate that the origin of the parental melts of the Timar basalts is metasomatized lithospheric mantle source and then these melts reached the surface from the fissures that is related to extensional tectonics in Pliocene. • The post-collisional Pliocene Timar basalts in the Turkish-Iranian high plateau. • The Geochemical and geochronological features of the Timar basalts. • The partial melting of a metasomatized spinel–rich lithospheric mantle source. • The EC-AFC modelling for the Pliocene Timar basalts. [ABSTRACT FROM AUTHOR]