Coupled Zircon Trace Element Systematics and Whole-Rock Geochemistry in Neoproterozoic A-Type Granites

A-type granites represent high-temperature, highly differentiated felsic magmas formed in post-collisional and intraplate tectonic settings. While whole-rock geochemistry constrains bulk melt evolution, zircon trace element systematics provide higher-resolution insights into crystallization conditions, including temperature, oxidation state, and differentiation intensity. This study integrates whole-rock geochemical data with zircon trace element analyses to evaluate the extent to which zircon records magmatic evolution in Neoproterozoic A-type granites from Sinai, Egypt. Whole-rock compositions define a high-silica, ferroan differentiation trend characterized by enrichment in high-field-strength elements (HFSE) and pronounced negative Ba–Sr–Ti anomalies, indicating advanced fractional crystallization. Zircon trace element patterns exhibit strong heavy rare earth element (HREE) enrichment (Yb up to 1757 ppm), systematically negative Eu anomalies (mean Eu/Eu* = 0.32), and elevated Hf concentrations (up to 14,453 ppm; mean = 4763 ppm), reflecting progressive melt differentiation. Ti-in-zircon thermometry yields crystallization temperatures ranging from 562 °C to 1384 °C. However, most values cluster between 757 °C and 872 °C (mean ≈ 837 °C), indicating sustained high-temperature magmatic conditions. The broader temperature range likely reflects analytical uncertainties, assumptions in Ti activity, and possible outliers. Positive Ce anomalies indicate moderately oxidized crystallization environments. Systematic relationships among zircon Hf, Eu/Eu*, Yb/Gd, Th/U, and Ti-in-zircon temperatures demonstrate a strong coupling between zircon chemistry and whole-rock differentiation trends. These relationships are supported by statistically significant correlations, indicating that zircon trace element systematics provide a robust, semi-quantitative framework for interpreting melt evolution, while preserving independent constraints on temperature and redox state.