Petrogenesis of I-type granitoids from the Kiki Batholith, north-central Iran

The Kiki Batholith in the north Semnan Mountains of north- زentral Iran consists of granite, granodiorite, diorite, and gabbrodiorite sharply intruding Precambrian units. All rocks aremetaluminous to slightly peraluminous, defining a calcalkalic trend. Rare earth elementpatterns indicate that all studied rock types are comagmatic. Mineralogic, petrographic, and major- and trace-element data demonstrate that all rocks are I-type granitoids and crustal material along with derived mantle material may have contributed to their formation. Spider diagrams show troughs for Ti, P, and Nb, indicating magma genesis in a subductionzone setting. Other geochemical evidences such as high SiO2, low Mg# and transitional elements, and also Nb/La, Nb/Ce and (La/Sm) n average ratios indicate that the lower crust with derived mantle material had played an important role in generation of the Kiki granites.