Supplemental Material: Volcanic record of the arc-to-rift transition onshore of the Guaymas basin in the Santa Rosalía area, Gulf of California, Baja California

Item S1: Analytical methods, including XRF and ICP-MS whole-rock geochemical analysis, ⁴⁰Ar-³⁹Ar geochronological analytical methods, and zircon isotopic methods. Item S2: Excel spreadsheet of whole-rock geochemical data, including XRF and LA-ICPMS data. Item S3: ⁴⁰Ar-³⁹Ar geochronological data: Summary table, and data tables and plots for each sample. Item S4: U-Pb zircon data. Item S5. Hf-isotope zircon data. Item S6: Outcrop photos. Item 7: Photomicrographs, including examples of all samples dated by ⁴⁰Ar-³⁹Ar. Item S8: Summary of published definitions of adakites and high magnesium andesites. Item S9: KMZ files for geologic maps.