Experimental determination of H 2 O and CO 2 solubilities of mafic alkaline magmas from Canary Islands

International audienceWe present new H 2 O and CO 2 solubility data in mafic to intermediate alkaline magmas from Fasnia and Garachico volcanoes, Tenerife. H 2 O-and CO 2-saturated experiments were conducted at ∼50-400 MPa, 1200°C, and f O 2 from 2 log units below the NiNiO solid buffer to 3.2 log units above it. Although existing solubility models for alkali-rich mafic magmas broadly describe H 2 O and CO 2 behaviour, associated errors are worthy of consideration since they usually exceed 15-20%. For this reason, we have determined the specific solubility laws of basanitic and phonotephritic melts from the Canary Islands. Results show similar H 2 O solubilities for both compositions, whereas the basanite can dissolve an average of ∼45% more CO 2 than the phonotephrite. By combining these data, we have established a simple empirical model that allows us to calculate melt inclusion entrapment pressures accurately and, therefore, better understand the inner workings of volcanic oceanic islands. Application to El Hierro 2011-2012 and young (