Experimental simulation of bubble nucleation and magma ascent in basaltic systems : implications for Stromboli volcano.

Abstract : The ascent of H2O- and HO-CO2-bearing basaltic melts from the deeper to the shallower part of the Stromboli magmatic system and their vesiculation were simulated from decompression experiments. A well-studied “golden” pumice produced during an intermediate to a large-scale paroxysm was used as starting material. Volatile-bearing glasses were synthesized at an oxygen fugacity (fO2) ranging from NNO–1.4 to +0.9, 1200°C and 200 MPa. The resulting crystal and bubble-free glasses were then isothermally (1200°C) decompressed to final pressures Pf ranging between 200 and 25 MPa, at a linear ascent rate of 1.5 m/s (or 39 kPa/s) prior to be rapidly quenched.