Mineral chemical and Fe-Zn isotope evidence for buoyancy-driven plagioclase segregation in the Bushveld Complex

This dataset accompanies the study “Mineral chemical and Fe-Zn isotope evidence for buoyancy-driven plagioclase segregation in the Bushveld Complex.” It includes mineral major- and trace-element compositions of pyroxenes and plagioclase, together with whole-rock Fe and Zn isotope data, from stratigraphically constrained samples of the Eastern Bushveld Complex, South Africa.The dataset was generated to test whether Bushveld cumulate stratigraphy mainly reflects simple progressive evolution of the resident melt or cotectic crystallization followed by density-driven crystal sorting and mineral redistribution. Samples cover major lithological units, including pyroxenite, harzburgite, dunite, chromitite, norite, anorthosite, magnetite ore, and felsite caprock. Mineral major elements were analyzed by electron probe microanalysis, trace elements by LA-ICP-MS, and whole-rock Fe-Zn isotopes by MC-CC-ICP-MS. The data show positive correlations between Cr and Al contents in pyroxenes from the Lower and Critical zones, weaker correlations in more plagioclase-rich rocks from higher stratigraphic levels, negative Eu and Sr anomalies in pyroxenes, and complementary positive Eu and Sr anomalies in plagioclase. These features indicate persistent plagioclase crystallization during Bushveld chamber evolution but variable retention of plagioclase in the final cumulates. Overlapping plagioclase An values among major stratigraphic units and the absence of systematic whole-rock Fe-Zn isotope trends further suggest that the stratigraphy cannot be explained solely by progressive melt differentiation. These data can be used to evaluate mineral-scale records of cotectic crystallization, trace-element evidence for plagioclase retention and redistribution, and the role of Fe-Zn isotopes as chamber-scale constraints on melt evolution in layered intrusions. Whole-rock Fe-Zn isotope data should be interpreted as boundary conditions rather than direct tracers of plagioclase segregation.