Data for: Potassium Isotopes Trace Progressive Fluid Exsolution and Enhanced Melt Mobility in the Zoned Granite–Pegmatite System

This dataset supports the manuscript entitled “Potassium Isotopes Trace Progressive Fluid Exsolution and Enhanced Melt Mobility in the Zoned Granite–Pegmatite System”. The dataset includes whole-rock major- and trace-element data, potassium isotope compositions of whole-rock samples and quartz-hosted fluid inclusions, parameters used for Rayleigh fractionation modeling, viscosity calculation results, and numerical source data used to generate the figures. These data are used to evaluate fluid exsolution, melt–fluid evolution, and enhanced melt mobility in the Jiajika granite–pegmatite system.