Thermodynamic modelling and global dataset for arc magma differentiation (alphaMELTS outputs and geochemical compilation)

This dataset supports the manuscript “Deconstructing arc magma evolution: Pressure, oxygen fugacity, and source controls from MELTS modelling and global geochemistry”, which presents a quantitative framework for separating mantle source and differentiation controls in arc magmatism. Supplementary Table S1. Curated global arc major element dataset (6014 samples) with SiO₂, TiO₂, Al₂O₃, FeOₜ, MgO, and arc classification. Supplementary Table S2. Curated global arc REE dataset with La, Sm, Yb concentrations. Supplementary Table S3. Synthetic MELTS output from fractional crystallization simulations (1–5 kbar, 0.5–5 wt% H₂O, NNO–1 to NNO+2). Supplementary Text S4. Python scripts for MELTS batch simulations (01_run_melts_batch.py) and figure generation (02_plot_all_figures.py). Supplementary Text S5. README.txt file with archive description and instructions. Supplementary Figure S6. Leave‑one‑arc‑type‑out cross‑validation of modelled compositional ranges. For each arc type (intra‑oceanic, continental, collisional), the fraction of samples falling within the 5th–95th percentile range defined by the other two arc types is shown. Results are shown separately for (a) SiO₂, (b) Al₂O₃, (c) FeOₜ, and (d) TiO₂. Error bars represent 95% confidence intervals from bootstrap resampling (n = 1000). The dashed red line at 90% is a visual reference. Supplementary Table S7. Leave‑one‑arc‑type‑out cross‑validation results. For each target arc type (left out during training), the table reports: Test_n (number of samples in the left‑out arc type), and for each element (SiO₂, Al₂O₃, FeOₜ, TiO₂): the fraction (%) of samples falling inside the 5th–95th percentile range defined by the other two arc types, with 95% confidence intervals (from bootstrap resampling, n = 1000). Supplementary Table S8. Kruskal–Wallis test results comparing major element compositions between intra-oceanic, continental, and collisional arcs at MgO = 4–5 wt%. For each element (FeOₜ, TiO₂, Al₂O₃, SiO₂), the table reports: the number of samples per arc type (n_intra_oceanic, n_continental, n_collisional), the Kruskal–Wallis H statistic, the p-value, and significance status (p < 0.05 = significant). Supplementary Figure S9. Boxplots comparing major element compositions between intra-oceanic (blue), continental (orange), and collisional (green) arcs at MgO = 4–5 wt%. Results are shown for (a) FeOₜ, (b) TiO₂, (c) Al₂O₃, and (d) SiO₂. Individual data points are shown as semi‑transparent dots with horizontal jitter to reduce overplotting. Kruskal–Wallis test results are annotated in each panel (*** = p < 0.001).