volcanoes; soil gases; carbon dioxide; helium; radon; alteration; Piton de la Fournaise
Abstract :
[en] Airborne atmospheric and in-situ soil gas analyses demonstrate that distal gas leaks are non-existent at Piton de la Fournaise (PF) despite frequent eruptions. Airborne traverses made at a constant altitude indicated that no detectable large-scale CO2 degassing occurs from the volcano. In-situ soil gas traverses (CO2, He-4, Rn-222) across the active riftzones, the summit crater and the caldera rims, show both a lack of positive anomalies and evidence of strong depleted concentrations for He and CO2 with respect to air. Depletions in soil He is explained by intense rain water infiltration. A more unexpected result lies in the very low CO2 concentrations (down to 92 ppm) in bare soils in the summit region. Such a depletion was not previously reported and is attributed to considerable basalt weathering operating as the result of huge runoff. A model has enabled both the runoff and the CO2 consumption occurring within the basaltic layers to be calculated. Data obtained are consistent with values expected from large-scale erosion models and with the local calculated diffusive flux of CO2 in soils. The huge runoff, together with the basaltic lithology of the volcano, are found to be the main factor controlling the soil gas signatures at PF. (C) 2002 Elsevier Science B.V. All rights reserved.
Disciplines :
Earth sciences & physical geography
Author, co-author :
Toutain, J. P.; Observatoire Midi-Pyrénées, Toulouse, France > LMTG > Géochimie des Interactions Crustales
Baubron, J. C.; BRGM > Service Géologique Régional Lorraine, Vandoeuvre-les-Nancy, France
François, Louis ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Modélisation du climat et des cycles biogéochimiques
Language :
English
Title :
Runoff control of soil degassing at an active volcano. The case of Piton de la Fournaise, Reunion Island
Baubron J.-C., Allard P., Toutain J.-P. (1990) Diffuse volcanic emissions of carbon dioxide from Vulcano island (Italy). Nature 344:51-54.
Wilkening M. Radon in the Environment, Elsevier, New York; 1990.
Allard P., Carbonnelle J., Dajlevic D., Le Bronec J., Morel P., Robe M.-C., Maurenas J.-M., Faivre-Pierret R., Martin D., Sabroux J.-C., Zettwoog P. (1991) Eruptive and diffuse emissions of CO2 from Mount Etna. Nature 351:387-391.
Farrar C.D., Sorrey M.L., Evans W.C., Howles J.F., Kerr B.D., Kennedy B.M., King C.Y., Southon J.R. (1995) Forest-killing diffuse CO2 emission at Mammoth Mountain as a sign of magmatic unrest. Nature 376:675-678.
Williams-Jones G., Stix J., Heiligmann M., Charland A., Sherwood Lollar B., Garzón V., Barquero J., Fernandez E. (2000) A model of diffuse degassing at three subduction-related volcanoes. Bull. Volcano 62:130-142.
Pinault J.-L., Baubron J.-C. (1996) Signal processing of radon, moisture and temperature in soils: A new approach for radon concentration modelling. J. Geophys. Res 101:3157-3171.
Pinault J.-L., Baubron J.-C. (1997) Signal processing diurnal and semidiurnal variations in radon and atmospheric pressure: A new tool for accurate in-situ measurements of soil gas velocity, pressure gradient, and tortuosity. J. Geophys. Res 102:18101-18120.
Baubron J.-C., Allard P., Sabroux J.-C., Tedesco D., Toutain J.-P. (1991) Soil gas emanations as precursory indicators of volcanic eruptions. J. Geol. Soc. London 148:571.
Rahn T.A., Fessenden J.E., Wahlen M. (1996) Flux measurements of anomalous CO2 emission from the flanks of Mammoth Mountain, California. Geophys. Res. Lett 23:1861-1864.
Rogie J.D., Derill M.K., Sorey M.L., Chiodini G., Galloway D.L. (2001) Dynamics of carbon dioxide emission at Mammoth Mountain, California. Earth Planet. Sci. Lett 188:535-541.
Aubert M., Baubron J.-C. (1988) Identification of a hidden thermal fissure in a volcanic terrain using a combination of hydrothermal convection indicators and soil atmosphere analysis. J. Volcanol. Geotherm. Res 35:217-225.
Thomas D.M., Cox M.E., Cuff K.E. (1986) The association between ground gas radon variations and geologic activity in Hawaii. J. Geophys. Res 91:12186-12198.
Toutain J.-P., Baubron J.-C., Allard P., Briole P., Marty B., Tedesco D., Miele G., Le Bronnec J. (1992) Continuous monitoring of distal gas emanations at Vulcano, Southern Italy. Bull. Volcanol 54:147-155.
Connor C., Hill B., LaFemina P., Navarro M., Conway M. (1996) Soil 222Rn pulse during the initial phase of the June-August 1995 eruption of Cerro Negro, Nicaragua. J. Volcanol. Geotherm. Res 73:119-127.
Baxter J.-P., Baubron J.-C., Coutinho R. (1999) Health hazards and disaster potential of ground emissions at Furnas volcano, Sao Miguel, Azores. J. Volcanol. Geotherm. Res 92:95-109.
Gillot P.-Y., Nativel P. (1989) Eruptive history of the Piton de la Fournaise volcano, Réunion Island, Indian Ocean. J. Volcanol. Geotherm. Res 13:131-146.
Lénat J.-F. Structure et dynamique interne d'un volcan basaltique intraplaque océanique: Le Piton de la Fournaise (lle de la Réunion), Thesis, Université de Clermont II; 1987.
Toutain J.-P., Bachelery P., Blum P.-A., Cheminée J.-L., Delorme H., Fontaine L., Kowalski P., Taochy P. (1992) Real time monitoring of vertical ground deformations during eruptions at Piton de la Fournaise. Geophys. Res. Lett 19:553-556.
Bachèlery P., Mairine P. (1990) Volcano-structural evolution of Piton de la Fournaise during the last 0.53 Ma. Le Volcanisme de la Réunion , J.F. Lénat (Ed.), Monographie, CRV, Clermont-Ferrand; 213-242.
Michel S., Zlotnicki J. (1995) Le dynamisme de la Fournaise estil controlé par l'anisotropie structurale lithosphȩrique N120° située sous l'ile de la Réunion?. C.R. Acad. Sci 321:643-650.
Bachèlery P., Lénat J.-F. (1989) Evidence and constraints for the presence of a shallow reservoir at Piton de la Fournaise (Réunion). Proceedings of the IAVCEI General Assembly, Continental Magmatism, Santa Fe, New Mexico Bureau of Mines and Mineral Ressources; .
Toutain J.-P., Baubron J.-C. (1999) Gas geochemistry and seismotectonics: A review. Tectonophysics 304:1-27.
Jenkins A.C., Cook A. Argon, Helium and the Rare Gases, History, Occurrence and Properties, Interscience Publishers, London; 1961.
Kahler D.E. (1981) Helium: A gaseous geochemical guide to faults, fractures and geothermal systems. Geotherm. Res. Counc. Trans 5:87-89.
Klusman R.W. Soil Gas and Related Methods for Natural Resource Exploration, Wiley, Chichester; 1993.
Gerlach T.M., Doukas M.P., McGee K.A., Kessler R. (1999) Airbone detection of diffuse carbon dioxide emissions at Mammoth Mountains, California. Geophys. Res. Lett 26:3661-3664.
Amiotte-Suchet P., Probst J.-L. (1995) A global model for present-day atmospheric/soil CO2 consumption by chemical erosion of continental rocks (GEM-CO2). Tellus 47 B:273-280.
Louvat P., Allègre C.J. (1997) Present denudation rates at Réunion island determined by river geochemistry: Basalt weathering and mass budget between chemical and mechanical erosions. Geochim. Cosmochim. Acta 61:3645-3669.
Dessert C., Dupré B., François L.M., Schott J., Gailardet J., Chakrapani G.J., Badjope S. (2001) Erosion of Deccan traps determined by river geochemistry: Impact on the global climate and the 87Sr/86 Sr ratio of seawater. Earth Planet. Sci. Lett 188:459-474.
Fang C., Moncrieff J.B. (1999) A model for soil CO2 production and transport. I model development. Agric. For. Meteorol 95:225-236.
Hubert B., François L., Warnant P., Strivay D. (1998) Stochastic generation of meteorological variables and effects on global models of water and carbon cycles in vegetation and soils. J. Hydrol 212-213:317-334.
François L., Probst A., Goddéris Y., Schott J., Rasse D., Viville D., Pokrovsky O., Dupré B. (2001) A new model of rock weathering: Design and validation on a small granitic catchment. International Association of Geochemistry , Proceedings of WRI-10 Conference, Balkema, Rotterdam; 391-394.
Guy C., Schott J., Destrigneville C., Chiappini R. (1992) Low-temperature alteration of basalt by interstitial seawater, Mururoa, French Polynesia. Geochim. Cosmochim. Acta 56:4169-4189.
Cox M.E. (1983) Summit outgassing as indicated by radon, mercury and pH mapping, Kilauea volcano, Hawaii. J. Volcanol. Geotherm. Res 16:131-151.
Zlotnicki J., Michel S., Annen C. (1994) Anomalies de polarisation spontanée et systèmes convectifs sur le volcan du Piton de la Fournaise (Ile de la Réunion, France). C.R. Acad. Sci 318:1325-1331.
Lénat J.-F. (1989) Patterns of volcanic activity of Piton de la Fournaise (Réunion Island, Indian Ocean), A synthesis based on monitoring data between 1980 and July 1985, and on historical records since 1930. Proc. Volcanol., Volcanic Hazards , Springer, Berlin; 312-338.
Coudray J., Mairine P., Nicolini E., Clerc J.-M. (1990) Hydrological approach. Le Volcanisme de la Réunion, J.-F. Lénat (Ed.), Monographie, C.R.V., Clermont-Ferrand; .
