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| Mougel, Berengere; Moreira, Manuel; Agranier, Arnaud. |
| We investigate in details helium isotope data reported in Mougel et al. (2014) for 14 basaltic samples collected on the East Pacific Rise by submersible (15 degrees 4N) where the ridge interacts with the Mathematician seamounts. Samples locations are separated by only few hundred meters across a 15km along-axis profile. The data reveal a strong geochemical variability that has never been observed at such high spatial resolution for helium isotope compositions. Moreover, they reveal an unusually high He-4/He-3 mantle component also characterized by unradiogenic lead, atypical in oceanic basalts. He-Pb systematics suggests a mixture between a nonradiogenic lead and radiogenic helium pyroxenitic component, recycled from the deep continental lithosphere and... |
| Tipo: Text |
Palavras-chave: Helium; Isotopes; Mantle geochemistry; MORB; Hot spot; EPR. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00639/75140/75500.pdf |
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| Peron, Sandrine; Moreira, Manuel; Agranier, Arnaud. |
| We review the different scenarios for the origin of light noble gases (He, Ne, and Ar) on Earth. Several sources could have contributed to the Earth's noble gas budget: implanted solar wind, solar nebula gas, chondrites, and comets. Although there is evidence for solar-like neon in the Earth's mantle, questions remain as to its origin. A new compilation of noble gas data in lunar soils, interplanetary dust particles, micrometeorites, and solar wind allows examination of the implanted solar wind composition, which is key to understanding the solar-like mantle neon isotope composition. We show that lunar soils that reflect this solar-wind-implanted signature have a Ne-20/Ne-22 ratio very close to that of ocean island basalts. New data and calculations... |
| Tipo: Text |
Palavras-chave: Volatile origin; Helium; Neon; Argon; Solar wind implantation. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00638/74992/75837.pdf |
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| Mollex, Gaelle; Furi, Evelyn; Burnard, Pete; Zimmermann, Laurent; Chazot, Gilles; Kazimoto, Emmanuel O.; Marty, Bernard; France, Lyderic. |
| Oldoinyo Lengai is the only volcano on Earth currently erupting natrocarbonatites, of which the source and genesis remain controversial. Cognate xenoliths and fumaroles were sampled at the summit of Oldoinyo Lengai, and deep crustal xenoliths from Oltatwa maar, in 2010 and 2014, after the 2007-2008 sub-Plinian eruption. The summit cognate xenoliths provide direct information on the isotopic composition of the mid-crustal magma chamber that was active during the 2007-2008 explosive eruption. Cognate xenolith-hosted pyroxenes from Oldoinyo Lengai have an average He-3/He-4 = 6.58 +/- 0.46 R-A, similar to values from nearby silicate volcanoes (4.95-7.30 R-A), and reflecting a sub-continental lithospheric mantle (SCLM) signature. This similarity implies that... |
| Tipo: Text |
Palavras-chave: Carbonatite; Neon; 2007-2008 eruption; SCLM; Cognate xenoliths; Helium; Neon; Argon. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00638/74994/75820.pdf |
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| Burnard, P.; Bourlange, S.; Henry, Pierre; Geli, Louis; Tryon, M. D.; Natal'In, B.; Sengor, A. M. C.; Ozeren, M. S.; Cagatay, M. N.. |
| Fluids venting from the submarine portion of the Marmara Main Fault (part of the North Anatolian Fault system, Turkey) were sampled in Ti bottles deployed by submersible. The fluids consist of mixtures of fault derived gases, fault related cold seep fluids, and ambient seawater; these components can readily be distinguished using the isotopes of He and the He/Ne ratios. He-3/He-4 ratios range between 0.03 +/- 0.1 and 4.9 +/- 0.4 Ra, indicating that both crustal and mantle derived sources of helium are sampled by the fault. The dominant gas in all the samples analyzed is methane with the abundance of CO2 below detection (<= 2%) in the mantle rich (high He-3/He-4) fluids. This is in contrast to nearly all mantle derived fluids where the C species are... |
| Tipo: Text |
Palavras-chave: Fluids; Gas emission; Helium; Marmara Sea; North Anatolian Fault. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00098/20954/18576.pdf |
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