Search results for "Basalt"
showing 3 items of 223 documents
Phase equilibria of Pantelleria trachytes (Italy): constraints on pre-eruptive conditions and on the metaluminous to peralkaline transition in silici…
2018
Pantelleria Island is the type locality of pantellerite, an iron and alkali-rich rhyolite (P.I=molar Na2O+K2O/Al2O3 >1.05). Peralkaline rhyolites (i.e pantellerite and comendite) and trachytes usually represent the felsic end-members in continental rift systems (e.g., Pantelleria, Tibesti, Ethiopia, Afar, Kenya, Bain and Range, South Greenland) and in oceanic sland settings (Socorro Is., Easter Is., Iceland and Azores). The origin of peralkaline rhyolites in the different tectonic settings is still a matter of debate and three hypotheses have been suggested: (a) crystal fractionation of alkali-basalt in a shallow reservoir to produce a trachyte which subsequently gives rise to a pantelle…
Experimental Constraints on the Deep Magma Feeding System at StromboliVolcano, Italy
2009
International audience; New experiments have been performed on a high-K basalt (PST-9) from Stromboli volcano, Italy, to constrain the physical conditions of golden pumice magmas at their storage level and discuss their petrogenesis. Fluid-present, H2O- and CO2-bearing, near-liquidus experiments were performed at 11508C between 100 and 400MPa and under oxidizing conditions. Glasses were analyzed by Fourier transform IR spectroscopy and their H2O and CO2 concentrations compared with those in glass inclusions.Most glass inclusions cluster near the 200MPa isobar, suggesting entrapment at a depth of ~8 km. Golden pumice magmas have viscosities of 7.9 Pa s and densities of 2.48-2.57 g/cm3. Compo…
A model of degassing for Stromboli volcano
2010
International audience; A better understanding of degassing processes at open-vent basaltic volcanoes requires collection of new datasets of H2O–CO2–SO2 volcanic gas plume compositions, which acquisition has long been hampered by technical limitations. Here, we use the MultiGAS technique to provide the best-documented record of gas plume discharges from Stromboli volcano to date. We show that Stromboli's gases are dominated by H2O (48–98 mol%; mean, 80%), and by CO2 (2–50 mol%; mean, 17%) and SO2 (0.2–14 mol%; mean, 3%). The significant temporal variability in our dataset reflects the dynamic nature of degassing process during Strombolian activity; which we explore by interpreting our gas m…