Remote and in situ plume measurements of acid gas release from La Soufrière volcano, Guadeloupe

Bernard, Marie-Lise; Molinié, Jack; Petit, R.H.; Beauducel, François; Hammouya, G.; Marion, Guy

doi:10.1016/j.jvolgeores.2005.08.001

Cited by 23 publications

(26 citation statements)

References 41 publications

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“…Detailed field studies reveal that diffuse CO 2 ‐H 2 S degassing occurs commonly along the dense network of faults (OVSG‐IPGP data base, Allard et al ., ). On these islands, the CO 2 dominates the gaseous emissions (about 70% of dry gas), followed by hydrogen sulfide (H 2 S) (up to 29% of dry gas), sulfuric acid (SO 2 ) (< 1% of dry gas) and hydrogen chloride (HCl) (110–210 ppmv) (OVSG‐IPGP data base, Pedroni et al ., ; Brombach et al ., ; Bernard et al ., ; Joseph et al ., ). Isotope compositions of CO 2 (δ 13 C = –3 · 5 ± 0 · 7‰, OVSG‐IPGP data base, Pedroni et al ., ; Brombach et al ., ; Agrinier et al ., ) and of helium (He) ( 3 He/ 4 He at R/Ra ~ 8, Pedroni et al ., ; Ruzié et al ., ) confirm that the degassed volatiles have a mantle source.…”

Section: Geological and Hydrological Settingsmentioning

confidence: 99%

Carbon isotopes in the rivers from the Lesser Antilles: origin of the carbonic acid consumed by weathering reactions in the Lesser Antilles

Rivé

Gaillardet

Agrinier

et al. 2013

Earth Surf Processes Landf

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International audienceIn this paper, we use carbon isotopes in the dissolved load of rivers from the Lesser Antilles volcanic arc (Guadeloupe, Martinique and Dominica islands) to constrain the source of the carbon dioxide (CO2) involved in the neutralization reactions during water-rock interactions. The d13C data span a large range of variations, from -19% to -5 _ 2% for DIC (dissolved inorganic carbon) concentrations ranging from 11 mM to 2000 mM. Coupled with major element concentrations, carbon isotopic ratios are interpreted as reflecting a mixture of magmatic CO2 (enriched in heavy carbon (d13C_-3 _ 5%) and biogenic CO2 produced in soils (enriched in light carbon (d13C<-17%)). Carbon isotopes show that, at the regional scale, 23 to 40% of CO2 consumed by weathering reactions is of magmatic origin and is transferred to the river system through aquifers under various thermal regimes. These numbers remain first-order estimates as the major uncertainty in using carbon isotopes as a source tracer is that carbon isotopes can be fractionated by a number of processes, including soil and river degassing. Chemical weathering is clearly, at least, partly controlled by the input of magmatic CO2, either under hydrothermal (hot) or surficial (cold) weathering regimes. This study shows that the contribution of magmatic CO2 to chemical weathering is an additional parameter that could explain the high weathering rates of volcanic rocks. The study also shows that a significant part of the carbon degassed from the Earth's interior is not released as CO2 to the atmosphere, but as DIC to the ocean because it interacts with the groundwater system. This study calls for a better understanding of the contributions of deep carbon to the hydrosphere and its influence on the development of the Critical Zone

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Section: Geological and Hydrological Settingsmentioning

confidence: 99%

Carbon isotopes in the rivers from the Lesser Antilles: origin of the carbonic acid consumed by weathering reactions in the Lesser Antilles

Rivé

Gaillardet

Agrinier

et al. 2013

Earth Surf Processes Landf

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“…This long‐term and misunderstood unrest has motivated, about 10 yr ago, a large community to concentrate their research efforts on the superficial hydrothermal system characterization. Various geophysical studies have been carried out to improve our understanding of the hydrothermal dynamics and inner geological structures (see for instance Jacob et al (2005), Nicollin et al (2006), Bernard et al (2006)). But seismic methods that are classically used on volcanoes have not been applied at La Soufrière since Dorel et al (1979), mostly because of the low rate of natural seismicity and the difficulty to operate dense seismic networks under tropical environment.…”

Section: Introductionmentioning

confidence: 99%

Joint inversion ofP-wave velocity and density, application to La Soufrière of Guadeloupe hydrothermal system

Coutant

Bernard

Beauducel

et al. 2012

Geophysical Journal International

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SUMMARY We present the result of a 3‐D gravity and P‐wave traveltime joint inversion applied to the hydrothermal system of La Soufrière of Guadeloupe. The joint inversion process is used here to overcome the different resolution limitations attached to the two data sets. P‐wave traveltimes were obtained from three active seismic surveys that were conducted from 2001 to 2007. Gravity data collected during a microgravity campaign is described in a companion paper. We use a joint inversion process based on a Bayesian formulation and a deterministic iterative approach. The coupling between slowness and density is introduced through a supplementary constraint in the misfit function that tries to minimize the distance between parameter values and a theoretical relationship. This relationship is derived from measurements on samples representative of Mt Pelée of Martinique and La Soufrière volcanoes. We chose a grid discretization that leads to an under‐determined problem that we regularize using spatial exponential covariance between the nodes parameters. Our results are compared to geophysical electromagnetic results obtained using resistivity and VLF surveys. They confirm the presence of highly contrasted dense/fast and light/slow zones in La Soufrière dome and crater basement. Our images suggest however that some non‐conductive zones may be massive andesite bodies rather than argilized zones, and that these bodies may have deeper roots than hypothesized.

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“…At the periphery, most gas emissions continued to wane. From 1998-99, plumes with a significant amount of HCl have been emitted from the summit and are visible from a few kilometers away (pH measurements from the Rapport de l'Observatoire Volcanologique et Sismologique de Guadeloupe (1976Guadeloupe ( -2006 and OP-FTIR remote measurements by Bernard et al (2006).…”

Section: Fumarolic Activitymentioning

confidence: 99%

Degassing at La Soufrière de Guadeloupe volcano (Lesser Antilles) since the last eruptive crisis in 1975–77: Result of a shallow magma intrusion?

Boichu

Villemant

Boudon

2011

Journal of Volcanology and Geothermal Research

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In the 15 years following the last crisis of phreatic type in 1975-77, the hydrothermal and seismic activity of La Soufrière de Guadeloupe has displayed an episodic behavior superimposed on a long-term decay, as inferred from seismicity and degassing, monitored through fumarolic emissions and Cl content in thermal springs. In particular, the evolution of the Cl content can be explained by a succession of magmatic gas injections into the hydrothermal system. This episodic supply of gas may be associated to the thermodynamic evolution of a batch of magma intruded at shallow depth around 1976. Progressive magma cooling, crystallization, gas exsolution and pressure buildup lead to cyclic failure of host rock around the intrusion, and episodic release of gas, with a decreasing frequency as cooling proceeds. This physical model allows to reproduce the pattern of degassing activity of La Soufrière, including the decreasing frequency of Cl pulses with time. Our preferred forward model of Cl pulses involves a magma intrusion volume in the range 0.01-0.52 km 3 and a tensile strength of the surrounding rock in the range 0.1-0.6 MPa. These results reinforce the hypothesis of a shallow magma intrusion triggering the 1975-77 crisis and provide an explanation for the degassing and seismic activities observed until 1992.

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Remote and in situ plume measurements of acid gas release from La Soufrière volcano, Guadeloupe

Cited by 23 publications

References 41 publications

Carbon isotopes in the rivers from the Lesser Antilles: origin of the carbonic acid consumed by weathering reactions in the Lesser Antilles

Carbon isotopes in the rivers from the Lesser Antilles: origin of the carbonic acid consumed by weathering reactions in the Lesser Antilles

Joint inversion ofP-wave velocity and density, application to La Soufrière of Guadeloupe hydrothermal system

Degassing at La Soufrière de Guadeloupe volcano (Lesser Antilles) since the last eruptive crisis in 1975–77: Result of a shallow magma intrusion?

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