caa a22 4500 47706261X CHVBK 20180405111405.0 cr unu---uuuuu 170330e19961201xx s 000 0 eng 10.1007/s004450050146 doi (NATIONALLICENCE)springer-10.1007/s004450050146 Fluid geochemistry of Montserrat Island, West Indies [Elektronische Daten] [G. Chiodini, R. Cioni, A. Frullani, M. Guidi, L. Marini, F. Prati, B. Raco]  Two geochemical surveys carried out in March 1991 and September 1992 revealed the existence of a hydrothermal system in the southern portion of Montserrat Island, below Soufrière Hills Volcano. This conclusion is supported by the presence of: (a) the thermal springs of Plymouth which are fed by deep Na-Cl waters (Cl concentration ∼25 000 mg/kg, temperature ca. 250  °C) mixed with shallow steam-heated waters; (b) the four fumarolic fields of Galway's Soufrière, Gages Upper Soufrière, Gages Lower Soufrière, and Tar River Soufrière, where acid to neutral, steam-heated waters are present together with several fumarolic vents, discharging vapors formed through boiling of hydrothermal aqueous solutions. Involvement of magmatic fluids in the recharge of the hydrothermal aquifers is suggested by: (a) the high 3He/4He ratios of fumarolic fluids, i.e., 8.2 RA at Galway's Soufrière and 5.9 RA at Gages Lower Soufrière; (b) the δD and δ18O values of Na-Cl thermal springs and steam condensates, indicating the involvement of arc-type magmatic water in the formation of deep geothermal liquids; and (c) the CH4/CO2 ratios of fumarolic fluids, which are lower than expected for equilibrium with the FeO-FeO1.5 hydrothermal rock buffer, but being shifted towards the SO2-H2S magmatic gas buffer. Springer-Verlag Berlin Heidelberg, 1996 Key words Montserrat Island nationallicence Soufrière Hills Volcano nationallicence Fluid geochemistry nationallicence Hydrothermal fluids nationallicence Magmatic fluids nationallicence Chiodini G. Dipartimento di Scienze della Terra, Università di Perugia, Piazza dell'Università, I-06100 Perugia, Italy, IT aut Cioni R. Ist. Geocronologia e Geochimica Isotopica, CNR, Via C. Maffi 36, I-56127 Pisa, Italy Fax: +39 50 900270, IT aut Frullani A. Geotermica Italiana srl, Lung'Arno Mediceo 16, I-56127, Pisa, Italy, IT aut Guidi M. Ist. Geocronologia e Geochimica Isotopica, CNR, Via C. Maffi 36, I-56127 Pisa, Italy Fax: +39 50 900270, IT aut Marini L. Dipartimento de Scienze della Terra, Università di Genova, Corso Europa 26, I-16132 Genova, Italy, IT aut Prati F. Geotermica Italiana srl, Lung'Arno Mediceo 16, I-56127, Pisa, Italy, IT aut Raco B. Dipartimento Scienze della Terra, Università di Pisa, Via Santa Maria 53, I-56126 Pisa, Italy, IT aut https://doi.org/10.1007/s004450050146 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s004450050146 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Chiodini G. Dipartimento di Scienze della Terra, Università di Perugia, Piazza dell'Università, I-06100 Perugia, Italy, IT aut NATIONALLICENCE 700 1- Cioni R. Ist. Geocronologia e Geochimica Isotopica, CNR, Via C. Maffi 36, I-56127 Pisa, Italy Fax: +39 50 900270, IT aut NATIONALLICENCE 700 1- Frullani A. Geotermica Italiana srl, Lung'Arno Mediceo 16, I-56127, Pisa, Italy, IT aut NATIONALLICENCE 700 1- Guidi M. Ist. Geocronologia e Geochimica Isotopica, CNR, Via C. Maffi 36, I-56127 Pisa, Italy Fax: +39 50 900270, IT aut NATIONALLICENCE 700 1- Marini L. Dipartimento de Scienze della Terra, Università di Genova, Corso Europa 26, I-16132 Genova, Italy, IT aut NATIONALLICENCE 700 1- Prati F. Geotermica Italiana srl, Lung'Arno Mediceo 16, I-56127, Pisa, Italy, IT aut NATIONALLICENCE 700 1- Raco B. Dipartimento Scienze della Terra, Università di Pisa, Via Santa Maria 53, I-56126 Pisa, Italy, IT aut Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer