%0 Journal Article
%A Rezaei Kahkaei, Mehdi
%A Galindo Francisco, María Del Carmen
%A Pankhurst, R.J.
%A Esmaeily, Dariush
%T Magmatic differentiation in the calc-alkaline Khalkhab–Neshveh pluton,Central Iran
%D 2011
%@ 1367-9120
%U https://hdl.handle.net/20.500.14352/42074
%X Geochemical and isotopic data (Sr, Nd) are presented for the Khalkhab–Neshveh pluton, an E-W elongatedbody of quartz monzogabbro, quartz monzodiorite, granodiorite and granite in the Urumieh–Dokhtar magmatic arc of Central Iran. The plutonic rocks are medium- to high-K, metaluminous, andI-type, with 52–71 wt.% SiO2. The geochemistry shows smooth differentiation trends in which mostmajor elements (except Al2O3, K2O and Na2O) are negatively correlated with SiO2; K2O, Ba, Rb, Ce, Nb,and Zr are positively correlated. Na2O, Sr, Eu and Y follow curves that are not considered to representsimple mixing between mafic and felsic magmas, but reflect crystal fractionation of clinopyroxene,plagioclase and hornblende. Initial 87Sr/86Sr ratios (~0.7047) and eNdt values (~+3.0) are essentiallyconstant, and the large volume of quartz monzogabbros compared to granites, as well as the lack of maficenclaves in more evolved rocks, are also indicative of crystal fractionation rather than mixing of magmasfrom different sources. Clinopyroxene fractionation was the main control in the evolution of the magmasup to 55% SiO2; hornblende took over from 55 wt.%, resulting in decreasing Dy/Yb with increasing silicacontent in the most siliceous rocks. Sr concentration increases up to 55% SiO2, and then decreasestogether with CaO, Al2O3, Na2O. Fractionation of opaque minerals and apatite throughout the sequence,and the continuous increase in K2O and Ba vs. SiO2 reflect the absence of significant fractionation of biotiteand K-feldspar. Based on geochemical and isotope data, geophysics information and field studies, itseems that suturing of the Arabia and Iran plates caused the Khalkhab and Koush nousrat faults with leftlateralstrike-slip in the Urumieh–Dokhtar region, and generated a purely tensional T space at 32º to thefaults which was exploited by the emplacement of Khalkhab–Neshveh pluton.
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