Petrography, geochemistry, U-Pb dating, Sr-Nd isotopes, and petrogenesis of Jalambadan igneous rocks, NW Sabzevar

Jalambadan area is located northwestern Sabzevar, Khorasan Razavi province, and southwestern Quchan-Sabzevar magmatic belt. Geology of the area includes of andesitic-trachyanesitic volcanic rocks, which is intruded by monzodioritic to dioritic subvolcanic intrusive rocks. The texture of igneous rocks is porphyry and the main minerals are plagioclase, alkali fldespar, pyroxene, hornblende, and magnetite. Age of intrusive rocks determined 44.7 to 45.2 Ma (Middle Eocene-Lutetian), using zircon U-Pb method. Geochemically, igneous rocks of the area are calc-alkaline and were formed at subduction zone. Relativelly, enrichment in LREE relative to HREE and enrichment of K, Rb, Cs, and Sr relative to Ti and Nb elements are observed in all of samples. Eu anomaly and Sr/Y ratios can be attributed to the presence of residual plagioclase and a few garnet in a source. (87Sr/86Sr)i (0.703708 to 0.704444), (143Nd/144Nd)i (0.512858 to 0..512933), and εNd I (5.42 to 6.88) values of intrusions and geochemical signatures of volcanic rocks indicate magma is drived from partial melting (7-5% for intrusions and 15-25% for volcanic rocks) of spinel lherzolite mantle wedge above subducted slab, which is assimilated slightly with upper continental crust very little.