Vesiculation in rhyolite at low H2O contents: A thermodynamic model

Abstract We present experimental data on the thermodynamics and kinetics of bubble nucleation and growth in weakly H 2 O‐oversaturated rhyolitic melts. The high‐temperature (900–1100°C) experiments involve heating of rhyolitic obsidian from Hrafntinnuhryggur, Krafla, Iceland to above their glass transition temperature ( Tg ∼ 690°C) at 0.1 MPa for times of 0.25–24 h. During experiments, the rhyolite cores increase in volume as H 2 O …