Garnet stability in arc basalt, andesite, and dacite—An experimental study

Garnet’s stability in arc magmas and its influences on their differentiation were explored experimentally in a typical basalt, andesite, and dacite at conditions of 0.9–1.67 GPa, 800–1300 °C, with 2–9 wt.% added H₂O, and with oxygen fugacity buffered near Re + O₂ = ReO₂ (~ Ni-NiO + 1.7 log₁₀ bars). Garnet did not grow at 0.9 GPa in any of the compositions, even with garnet seeds added to facilitate nucleation. At 1.0–1.2 GPa, garnet grew as thin rims (