8 results on '"Pelletier, B."'
Number of results to display per page
Search Results
2. Geodynamics of the southwest Pacific: a brief review and relations to New Caledonian geology
- Author
-
Collot, J., Patriat, M., Sutherland, R., Williams, S., Cluzel, D., Seton, M., Pelletier, B., Roest, W., Etienne, S., BORDENAVE Aurélien, Maurizot, P., Institut de sciences exactes et appliquées (ISEA), Université de la Nouvelle-Calédonie (UNC), and BUNC, Pole ID
- Subjects
[SDU.STU] Sciences of the Universe [physics]/Earth Sciences ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences - Published
- 2018
3. The low temperature hyperalkaline hydrothermal system of the Prony Bay (New Caledonia)
- Author
-
Pelletier, B., Monnin, C., Boulart, C., Chavagnac, V., Erauso, G., Gerard, M., Gerard, E., Guentas, L., Menez, B., Payri, C., Pisapia, C., Postec, A., Quémeneur, M., Laboratoire Insulaire du Vivant et de l'Environnement (LIVE), and Université de la Nouvelle-Calédonie (UNC)
- Subjects
010504 meteorology & atmospheric sciences ,[SDV]Life Sciences [q-bio] ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,010502 geochemistry & geophysics ,01 natural sciences ,6. Clean water ,Hydrothermal circulation ,Oceanography ,13. Climate action ,14. Life underwater ,Bay ,Geology ,ComputingMilieux_MISCELLANEOUS ,0105 earth and related environmental sciences - Abstract
The terrestrial hyperalkaline springs of the Prony bay (southern lagoon, New Caledonia) have been known since the XIXth century, but a recent high resolution bathymetric survey of the seafloor has revealed the existence of numerous submarine structures similar to the well-known Aiguille de Prony, which are also the location of high pH fluid discharge into the lagoon. During the HYDROPRONY cruise (28 October to 13 November 2011) samples of waters, gases and concretions have been collected by scuba divers at underwater vents. Four of these sampling sites are located in the Prony bay at depths up to 50 m. One (Bain des Japonais spring) is also in the Prony Bay but uncovered at low tide and another (Rivière des Kaoris spring) is on land slightly above the seawater level at high tide. We report the chemical composition (Na, K, Ca, Mg, Cl, SO4, Dissolved Inorganic Carbon, SiO2(aq)) of 45 water samples collected at 6 sites of high pH water discharge, as well as the composition of gases. Temperatures reach 37 °C at the Bain des Japonais and 32 °C at the spring of the Kaoris. Gas bubbling was observed only at these two springs. The emitted gases contain between 12 and 30% of hydrogen in volume of dry gas, 6 to 14% of methane, and 56 to 72% of nitrogen, with trace amounts of carbon dioxide, ethane and propane. pH values and salinities of all the 45 collected water samples range from the seawater values (8.2 and 35 g L−1) to hyperalkaline freshwaters of the Ca-OH type (pH 11 and salinities as low as 0.3 g L−1) showing that the collected samples are always a mixture of a hyperalkaline fluid of meteoric origin and ambient seawater. Cl-normalized concentrations of dissolved major elements first show that the Bain des Japonais is distinct from the other sites. Waters collected at this site are three component mixtures involving the high pH fluid, the lagoon seawater and the river water from the nearby Rivière du Carénage. The chemical compositions of the hyperalkaline end members (at pH 11) are not significantly different from one site to the other although the sites are several km away from each other and are located on different ultramafic substrata. The very low salinity of the hyperalkaline end members shows that seawater does not percolate through the ultramafic formation. Mixing of the hyperalkaline hydrothermal end member with local seawater produces large ranges and very sharp gradients of pH, salinity and dissolved element concentrations. There is a major change in the composition of the water samples at a pH around 10, which delimitates the marine environment from the hyperalkaline environment. The redox potential evolves toward negative values at high pH indicative of the reducing conditions due to bubbling of the H2-rich gas. The calculation of the mineral saturation states carried out for the Na-K-Ca-Mg-Cl-SO4-DIC-SiO2-H2O system shows that this change is due to the onset of brucite formation. While the saturation state of the Ca-carbonates over the whole pH range is typical of that found in a normal marine environment, Mg- and Mg-Ca-carbonates (magnesite, hydromagnesite, huntite, dolomite) exhibit very large supersaturations with maximum values at pH around 10, very well marked for the Bain des Japonais, emphasizing the role of water mixing in mineral formation. The discharge of high pH waters of meteoric origin into the lagoon marine environment makes the hydrothermal system of the Prony bay unique compared to other low temperature serpentinizing environments such as Oman (fully continental) or Lost City (fully marine).
- Published
- 2016
- Full Text
- View/download PDF
4. Propagation of back-arc extension into the arc lithosphere in the southern New Hebrides volcanic arc
- Author
-
Patriat, M., Collot, J., Danyushevsky, L., Fabre, M., Meffre, S., Falloon, T., Rouillard, P., Pelletier, B., Roach, M., Fournier, Marc, IFREMER Nouvelle Calédonie, Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Service Géologique de Nouvelle Calédonie, Geological Survey of New Caledonia, Department of Industry Mines and Energy-Department of Industry Mines and Energy, ARC Centre of Excellence in Ore Deposits, Tasmania University, ARC Centre of Excellence in Ore Deposits (CODES), University of Tasmania [Hobart, Australia] (UTAS), School of Physical Sciences [Hobart], ADECAL TECHNOPOLE, Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie]), Institut des Sciences de la Terre de Paris (iSTeP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), University of Tasmania (UTAS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), and Lagons, Ecosystèmes et Aquaculture Durable de Nouvelle Calédonie (LEADNC)
- Subjects
[SDU.STU]Sciences of the Universe [physics]/Earth Sciences - Abstract
International audience; New geophysical data acquired during three expeditions of the R/V Southern Surveyor in the southern part of the North Fiji Basin allow us to characterize the deformation of the upper plate at the southern termination of the New Hebrides subduction zone, where it bends eastward along the Hunter Ridge. Unlike the northern end of the Tonga subduction zone, on the other side of the North Fiji Basin, the 90° bend does not correspond to the transition from a subduction zone to a transform fault, but it is due to the progressive retreat of the New Hebrides trench. The subduction trench retreat is accommodated in the upper plate by the migration toward the southwest of the New Hebrides arc and toward the south of the Hunter Ridge, so that the direction of convergence remains everywhere orthogonal to the trench. In the back-arc domain, the active deformation is characterized by propagation of the back-arc spreading ridge into the Hunter volcanic arc. The N-S spreading axis propagates southward and penetrates in the arc, where it connects to a sinistral strike-slip zone via an oblique rift. The collision of the Loyalty Ridge with the New Hebrides arc, less than two million years ago, likely initiated this deformation pattern and the fragmentation of the upper plate. In this particular geodynamic setting, with an oceanic lithosphere subducting beneath a highly sheared volcanic arc, a wide range of primitive subduction-related magmas has been produced including adakites, island arc tholeiites, back-arc basin basalts, and medium-K subduction-related lavas.
- Published
- 2015
- Full Text
- View/download PDF
5. Atlas de la Nouvelle Calédonie
- Author
-
Collot, J.-Y., Pelletier, B., Lafoy, Y., Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Service de la Géologie de Nouvelle Calédonie, Direction de l'Industrie, des Mines et de l'Energie de Nouvelle Calédonie, Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Bonvallot, Jacques (coord.), Gay, Jean-Christophe (coord.), and Habert, Elisabeth (coord.)
- Subjects
GEOLOGIE MARINE ,BATHYMETRIE ,SUBDUCTION ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,GEOLOGIE STRUCTURALE ,ATLAS ,TOPOGRAPHIE ,ComputingMilieux_MISCELLANEOUS - Abstract
International audience
- Published
- 2012
6. La bathymétrie des marges de la Grande Terre et des îles Loyautés
- Author
-
Pelletier, B., Flamand, B., Perrier, J., Juffroy, F., Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), University IRD Noumea, Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie]), Géoazur (GEOAZUR 6526), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Nice Sophia Antipolis (1965 - 2019) (UNS), and COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,ComputingMilieux_MISCELLANEOUS - Abstract
International audience
- Published
- 2012
7. Prodigious emission rates and magma degassing budget of major, trace and radioactive volatile species from Ambrym basaltic volcano, Vanuatu island Arc
- Author
-
Pierre-Jean Gauthier, Emanuela Rita Bagnato, Alessandro Aiuppa, Francesco Parello, Hiroshi Shinohara, Nicole Métrich, Esline Garaebiti, Bernard Pelletier, G. M. Sawyer, Philipson Bani, Antonella Bertagnini, P. Allard, Vergniolle, N. (ed.), Métrich, N. (ed.), Institut de Physique du Globe de Paris (IPGP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Istituto Nazionale di Geofisica e Vulcanologia, Dipartimento DiSTeM, Università di Palermo, Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Palermo (INGV), Laboratoire Magmas et Volcans (LMV), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement et la société-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Jean Monnet [Saint-Étienne] (UJM), University IRD Noumea, Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie]), Institute of Geology and Geoinformation (Geological Survey of Japan), National Institute of Advanced Industrial Science and Technology (AIST), Department of Geography, University of Cambridge, University of Cambridge [UK] (CAM), Vanuatu Meteorology and Geohazards Department, Allard, P., Aiuppa, A., Bani, P., Métrich, N., Bertagnini, A., Gauthier, P., Shinohara, H., Sawyer, G., Parello, F., Bagnato, E., Pelletier, B., Garaebiti, E., Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Università degli studi di Palermo - University of Palermo, Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)
- Subjects
010504 meteorology & atmospheric sciences ,Lava ,Geochemistry ,Mineralogy ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,Ambrym ,Volatile fluxes ,010502 geochemistry & geophysics ,01 natural sciences ,Volcanic Gases ,Magma reservoir ,Vanuatu ,Volatile fluxe ,Geochemistry and Petrology ,Caldera ,event ,Geophysic ,ComputingMilieux_MISCELLANEOUS ,0105 earth and related environmental sciences ,Melt inclusions ,Basalt ,event.disaster_type ,geography ,geography.geographical_feature_category ,Magma degassing budget ,Strombolian eruption ,Geophysics ,Volcano ,13. Climate action ,Island arc ,Radioactive disequilibria ,Geology - Abstract
Ambrym volcano, in the Vanuatu arc, is one of the most active volcanoes of the Southwest Pacific region, where persistent lava lake and/or Strombolian activity sustains voluminous gas plume emissions. Here we report on the first comprehensive budget for the discharge of major, minor, trace and radioactive volatile species from Ambrym volcano, as well as the first data for volatiles dissolved in its basaltic magma (olivine-hosted melt inclusions). In situ MultiGAS analysis of H 2 O, CO 2 , SO 2 and H 2 S in crater rim emissions, coupled with filter-pack determination of SO 2 , halogens, stable and radioactive metals demonstrates a common magmatic source for volcanic gases emitted by its two main active craters, Benbow and Marum. These share a high water content (~ 93 mol%), similar S/Cl, Cl/F, Br/Cl molar ratios, similar ( 210 Po/ 210 Pb) and ( 210 Bi/ 210 Pb) activity ratios, as well as comparable proportions in most trace metals. Their difference in CO 2 /SO 2 ratio (1.0 and 5.6–3.0, respectively) is attributed to deeper gas-melt separation at Marum (Strombolian explosions) than Benbow (lava lake degassing) during our measurements in 2007. Airborne UV sensing of the SO 2 plume flux (90 kg s − 1 or 7800 tons d − 1 ) demonstrates a prevalent degassing contribution (~ 65%) of Benbow crater in that period and allows us to quantify the total volatile fluxes during medium-level eruptive activity of the volcano. Results reveal that Ambrym ranks among the most powerful volcanic gas emitters on Earth, producing between 5% and 9% of current estimates for global subaerial volcanic emissions of H 2 O, CO 2 , HCl, Cu, Cr, Cd, Au, Cs and Tl, between 10% and 17% of SO 2 , HF, HBr, Hg, 210 Po and 210 Pb, and over 30% of Ag, Se and Sn. Global flux estimates thus need to integrate its contribution and be revised accordingly. Prodigious gas emission from Ambrym does not result from an anomalous volatile enrichment nor a differential excess degassing of its feeding basalt: this latter contains relatively modest dissolved amounts of H 2 O (≤ 1.3 wt%), CO 2 (~ 0.10 wt%), S (0.075 wt%) and Cl (0.05 wt%), and its degassing under prevalent closed-system conditions well reproduces the composition of emitted volcanic gases. Instead, we show that the gas discharge is sustained by a very high basalt supply rate of 25 m 3 s − 1 , from a large (~ 0.5 km 3 ) magma reservoir probably emplaced at ~ 3.8 km depth below the summit caldera according to both the H 2 O-CO 2 content of bubble-free melt inclusions and preliminary seismic data. Radioactive disequilibria in the volcanic gases constrain that this reservoir may be entirely renewed in about 240 days. The comparatively low magma extrusion rate requires extensive convective overturn of the basaltic magma column and recycling of the unerupted (denser) degassed magma in the plumbing system, in agreement with textural features of erupted products. Finally, our results suggest that the Indian MORB-type mantle source of Ambrym basalts is modestly enriched in slab-derived water and other volatiles, in agreement with the prevalent volcanoclastic nature of subducted sediments and their lower subduction rate under the central Vanuatu arc due to its collision with the D'Entrecasteaux Ridge.
- Published
- 2016
- Full Text
- View/download PDF
8. Understanding volcanoes in the Vanuatu arc
- Author
-
Philippe Jean-Baptiste, Francesco Parello, Elise Fourré, Alessandro Aiuppa, Philipson Bani, Pierre-Jean Gauthier, Bernard Pelletier, Sergio Calabrese, Esline Garaebiti, Patrick Allard, Jean-Baptiste, P., Allard, P., Fourré, E., Bani, P., Calabrese, S., Aiuppa, A., Gauthier, P., Parello, F., Pelletier, B., Garaebiti, E., Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique du Globe de Paris (IPGP), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Dipartimento DiSTeM, Università di Palermo, Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA), University IRD Noumea, Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie]), Vanuatu Geohazards Observatory Port Vila, Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Glaces et Continents, Climats et Isotopes Stables (GLACCIOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Università degli studi di Palermo - University of Palermo, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Vergniolle, N. (ed.), Métrich, N. (ed.), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement et la société-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Jean Monnet [Saint-Étienne] (UJM), and Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])
- Subjects
010504 meteorology & atmospheric sciences ,Lava ,Earth science ,Geochemistry ,Vanuatu arc ,Helium isotopes ,[SDU.STU]Sciences of the Universe [physics]/Earth Sciences ,010502 geochemistry & geophysics ,01 natural sciences ,Volcanic fluids ,Volcanic Gases ,Geochemistry and Petrology ,event ,0105 earth and related environmental sciences ,Basalt ,event.disaster_type ,geography ,geography.geographical_feature_category ,Volcanic arc ,Hotspot contribution ,Fumarole ,Extinct and active volcanoes ,Mantle source ,Settore GEO/08 - Geochimica E Vulcanologia ,Geophysics ,Volcano ,13. Climate action ,Vanuatu arc, Volcanic fluids, Helium isotopes, Extinct and active volcanoes, Mantle source, Hotspot contribution ,Island arc ,Phenocryst ,Geology - Abstract
We report the first helium isotope survey of volcanic gases, hot springs and some olivine phenocrysts along the Vanuatu island arc, from Tanna in the south to Vanua Lava in the north. Low CO2 content and low He-3/He-4 ratios in thermal fluids of Epi (4.0 +/- 0.1 R-a), Efate (4.5 +/- 0.1 R-a) and Pentecost (5.3 +/- 0.5 R-a) islands coherently indicate reduced mantle gas leakage and crustal contamination by radiogenic helium on these extinct volcanic systems of the former (Pliocene) arc. Instead, presently active Vanuatu volcanoes display He-3/He-4 and C/He-3 ratios typical of subduction-related volcanic arcs: He-3/He-4 ratios range from 6.4 +/- 0.5 Ra in southernmost Tanna and 7.23 +/- 0.09 R-a in northernmost Vanua Lava to typical MORE values in the central islands of Gaua (7.68 +/- 0.06 R-a), Ambrym (7.6 +/- 0.8 R-a) and Ambae (7 2 R-a in groundwaters, 7.9 +/- 1.4 R-a in olivine phenocrysts, and 8.0 +/- 0.1 Ra in summit fumaroles of Aoba volcano). On Ambrym, however, we discover that hydrothermal manifestations separated by only 10-15 km on both sides of a major E-W transverse fault zone crossing the island are fed by two distinct helium sources, with different 3He/4He signatures: while fluids in southwest Ambrym (Baiap and Sesivi areas) have typical arc ratios (7.6 +/- 0.8 R-a), fluids on the northwest coast (Buama Bay area) display both higher He-3/He-4 ratios (9.8 +/- 02 R-a in waters to 10.21 +/- 0.08 R-a in bubbling gases) and lower C/He-3 ratios that evidence a hotspot influence. We thus infer that the influx of Indian MORB mantle beneath the central Vanuatu arc, from which Ambrym magmas originate, also involves a He-3-rich hotspot component, possibly linked to a westward influx of Samoan hotspot material or another yet unknown local source. This duality in magmatic He source at Ambrym fits with the bimodal composition and geochemistry of the erupted basalts, implying two distinct magma sources and feeding systems. More broadly, the wide He isotopic variations detected along the Vanuatu arc further verify the complex tectonic and magmatic framework of this intra-oceanic island arc.
- Published
- 2016
- Full Text
- View/download PDF
Catalog
Books, media, physical & digital resources
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.