Petrogenesis of a late-stage calc-alkaline granite in a giant S-type batholith: geochronology and Sr–Nd–Pb isotopes from the Nomatsaus granite (Donkerhoek batholith), Namibia

Abstract The late-tectonic 511.4 ± 0.6 Ma-old Nomatsaus intrusion (Donkerhoek batholith, Damara orogen, Namibia) consists of moderately peraluminous, magnesian, calc-alkalic to calcic granites similar I-type worldwide. Major and trace-element variations LREE HREE concentrations in evolved rocks imply that the fractionated mineral assemblage includes biotite, Fe–Ti oxides, zircon, plagioclase monazite. Increasing K 2 O abundance with increasing SiO suggests accumulation K-feldspar; compatible a small positive Eu anomaly most rocks. In comparison experimental data, granite was likely generated from meta-igneous sources possibly dacitic composition melted under water-undersaturated conditions (X H O: 0.25–0.50) at temperatures between 800 850 °C, zircon monazite saturation 812 852 respectively. has radiogenic initial 87 Sr/ 86 Sr ratios (0.7067–0.7082), relatively εNd values (− 2.9 − 4.8) Pb isotope ratios. Although Nd isotopic compositions do not vary or MgO contents, f Sm/Nd are negatively correlated indicating limited assimilation crustal components during monazite-dominated fractional crystallization. preferred petrogenetic model for generation involves continent–continent collisional setting stacking slices combination high radioactive heat production rates heated thickened crust, leading medium-P/high-T environment characteristic southern Central Zone orogen. Such promoted partial melting metasedimentary stages heating, followed by mid-crustal levels higher P–T late orogenic evolution.