caa a22 4500 475826442 CHVBK 20180406123829.0 cr unu---uuuuu 170329e20000601xx s 000 0 eng 10.1007/s004450000075 doi (NATIONALLICENCE)springer-10.1007/s004450000075 A model of diffuse degassing at three subduction-related volcanoes [Elektronische Daten] [Glyn Williams-Jones, John Stix, Martin Heiligmann, Anne Charland, Barbara Sherwood Lollar, N. Arner, Gustavo Garzón, Jorge Barquero, Erik Fernandez] and δ13C in soil gas were measured at three active subduction-related stratovolcanoes (Arenal and Poás, Costa Rica; Galeras, Colombia). In general, Rn, CO2 and δ13C values are higher on the lower flanks of the volcanoes, except near fumaroles in the active craters. The upper flanks of these volcanoes have low Rn concentrations and light δ13C values. These observations suggest that diffuse degassing of magmatic gas on the upper flanks of these volcanoes is negligible and that more magmatic degassing occurs on the lower flanks where major faults and greater fracturing in the older lavas can channel magmatic gases to the surface. These results are in contrast to findings for Mount Etna where a broad halo of magmatic CO2 has been postulated to exist over much of the edifice. Differences in radon levels among the three volcanoes studied here may result from differences in age, the degree of fracturing and faulting, regional structures or the level of hydrothermal activity. Volcanoes, such as those studied here, act as plugs in the continental crust, focusing magmatic degassing towards crater fumaroles, faults and the fractured lower flanks. Springer-Verlag, 2000 Diffuse degassing nationallicence Radon nationallicence Carbon dioxide nationallicence Poás nationallicence Arenal nationallicence Galeras nationallicence Williams-Jones Glyn Département de Géologie, Université de Montréal, Montréal, Québec, H3C 3J7, Canada e-mail: g.williams-jones@open.ac.uk Tel.: +44-1908-659023 Fax: +44-1908-655151, Canada aut Stix John Département de Géologie, Université de Montréal, Montréal, Québec, H3C 3J7, Canada e-mail: g.williams-jones@open.ac.uk Tel.: +44-1908-659023 Fax: +44-1908-655151, Canada aut Heiligmann Martin Department of Earth and Planetary Sciences, McGill University, Montréal, Québec, H3A 2A7, Canada, Canada aut Charland Anne Falconbridge Ltd., 3296 Francis-Hugues Avenue, Laval, Québec, H7L 5A7, Canada, Canada aut Sherwood Lollar Barbara Department of Geology, University of Toronto, Toronto, Ontario, M5S 3B1, Canada, Canada aut Arner N. Department of Geology, University of Toronto, Toronto, Ontario, M5S 3B1, Canada, Canada aut Garzón Gustavo INGEOMINAS, Observatorio Volcanológico y Sismológico, Pasto, A.A. 1795, Pasto, Colombia, Colombia aut Barquero Jorge Observatorio Volcanológico y Sismológico de Costa Rica, Universidad Nacional, Apartado 86-3000, Heredia, Costa Rica, Costa Rica aut Fernandez Erik Observatorio Volcanológico y Sismológico de Costa Rica, Universidad Nacional, Apartado 86-3000, Heredia, Costa Rica, Costa Rica aut Bulletin of Volcanology Springer-Verlag 62/2(2000-06-01), 130-142 0258-8900 62:2<130 2000 62 445 https://doi.org/10.1007/s004450000075 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s004450000075 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Williams-Jones Glyn Département de Géologie, Université de Montréal, Montréal, Québec, H3C 3J7, Canada e-mail: g.williams-jones@open.ac.uk Tel.: +44-1908-659023 Fax: +44-1908-655151, Canada aut NATIONALLICENCE 700 1- Stix John Département de Géologie, Université de Montréal, Montréal, Québec, H3C 3J7, Canada e-mail: g.williams-jones@open.ac.uk Tel.: +44-1908-659023 Fax: +44-1908-655151, Canada aut NATIONALLICENCE 700 1- Heiligmann Martin Department of Earth and Planetary Sciences, McGill University, Montréal, Québec, H3A 2A7, Canada, Canada aut NATIONALLICENCE 700 1- Charland Anne Falconbridge Ltd., 3296 Francis-Hugues Avenue, Laval, Québec, H7L 5A7, Canada, Canada aut NATIONALLICENCE 700 1- Sherwood Lollar Barbara Department of Geology, University of Toronto, Toronto, Ontario, M5S 3B1, Canada, Canada aut NATIONALLICENCE 700 1- Arner N. Department of Geology, University of Toronto, Toronto, Ontario, M5S 3B1, Canada, Canada aut NATIONALLICENCE 700 1- Garzón Gustavo INGEOMINAS, Observatorio Volcanológico y Sismológico, Pasto, A.A. 1795, Pasto, Colombia, Colombia aut NATIONALLICENCE 700 1- Barquero Jorge Observatorio Volcanológico y Sismológico de Costa Rica, Universidad Nacional, Apartado 86-3000, Heredia, Costa Rica, Costa Rica aut NATIONALLICENCE 700 1- Fernandez Erik Observatorio Volcanológico y Sismológico de Costa Rica, Universidad Nacional, Apartado 86-3000, Heredia, Costa Rica, Costa Rica aut NATIONALLICENCE 773 0- Bulletin of Volcanology Springer-Verlag 62/2(2000-06-01), 130-142 0258-8900 62:2<130 2000 62 445 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer