Interaction of the lithospheric mantle and crustal melts for the generation of the Horoz pluton (Nigde, Turkey): whole-rock geochemical and Sr-Nd-Pb isotopic evidence

The Horoz pluton includes granitic and granodioritic rocks, with widespread mafic microgranular enclaves (MMEs). Petrochemically, the rocks of the pluton show calc-alkaline to shoshonitic and metaluminous to slightly peraluminous composition. The rocks also exhibit an enrichment in large ion lithophile elements, e.g. Rb, K, and depletions of high field strength elements such as Y, Lu, and Mg#, Ni, with a slightly concave-upward rare earth element pattern. Both granitic and granodioritic rocks exhibit geochemical characteristics of tonalite, trondhjemite and granodiorite assemblages, possibly developed by the partial melting of a thickened lower crust. The granitoids have high concentrations of Na2O (2.6-4.5 wt%), Sr (347-599 ppm), intermediate-high (La/Yb)(N) (8.2-18.1, mostly >11), Al2O3 (13.2-16.9 wt%, average 15.3 wt%), low MgO (0.2-1.4 wt%, average 0.84 wt%) and Co (0.7-10.3 ppm). The MMEs include higher Na2O (4.5-5.5 wt%), Sr (389-1149 ppm), Al2O3 (16.9-19.2 wt%, average 17.8 wt%), MgO (1.4-4.4 wt%, average 2.75 wt%) and Co (6.2-18.7 ppm) contents in comparison with that of their hosts. There is a lack of negative Eu anomalies, except a few samples. Both host rocks and MMEs have a low initial Sr-87/Sr-86 ratio (respectively 0.7046-0.7051 and 0.7047-0.7058), low epsilon(Nd) value (-1.8 to -0.2 and -0.6 to 0.7 at 50 Ma) and highly radiogenic Pb-208/Pb-204 ratios (39.43-39.47 and 39.39-39.54). Whole-rock chemistry and isotopic data suggest that parent magmas of both MMEs and their hosts have derived from melts of the mixing between the lithospheric mantle and crustal end members, than fractional crystallization processes in crustal levels.