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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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| Deng, Zhengbin; Moynier, Frederic; Villeneuve, Johan; Jensen, Ninna K.; Liu, Deze; Cartigny, Pierre; Mikouchi, Takashi; Siebert, Julien; Agranier, Arnaud; Chaussidon, Marc; Bizzarro, Martin. |
| Despite the abundant geomorphological evidence for surface liquid water on Mars during the Noachian epoch (>3.7 billion years ago), attaining a warm climate to sustain liquid water on Mars at the period of the faint young Sun is a long-standing question. Here, we show that melts of ancient mafic clasts from a martian regolith meteorite, NWA 7533, experienced substantial Fe-Ti oxide fractionation. This implies early, impact-induced, oxidation events that increased by five to six orders of magnitude the oxygen fugacity of impact melts from remelting of the crust. Oxygen isotopic compositions of sequentially crystallized phases from the clasts show that progressive oxidation was due to interaction with an O-17-rich water reservoir. Such an early oxidation... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00686/79855/82697.pdf |
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| Fujii, Toshiyuki; Moynier, Frederic; Agranier, Arnaud; Ponzevera, Emmanuel; Abe, Minori; Uehara, Akihiro; Yamana, Hajimu. |
| Environmental transport of Tl is affected by redox reaction between Tl(I) and Tl(III) and ligand exchange reactions of them. In order to deepen the knowledge of Tl chemistry, we investigated fractionation of Tl stable isotopes (Tl-203 and Tl-205) in a chemical exchange system. Tl isotopes were fractionated in a liquid-liquid extraction system, in which aqueous and organic phases are hydrochloric acid solution and dichloroethane including a crown ether, respectively. After purification by ion-exchange chemistry, the isotope ratio of Tl-205/Tl-203 in equilibrated aqueous phase was measured precisely by multiple-collector-inductively-coupled-plasma-mass-spectrometry. A large isotope fractionation > 1 aEuro degrees was found. Electronic structures of... |
| Tipo: Text |
Palavras-chave: Thallium; Isotope fractionation; Redox; Ligand exchange; Nuclear field shift; Ab initio calculation. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00135/24624/22691.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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| Basile, Christophe; Girault, Igor; Paquette, Jean-louis; Agranier, Arnaud; Loncke, Lies; Heuret, Arnauld; Poetisi, Ewald. |
| We report the discovery of 173.4 Ma hotspot-related magmatic rocks in the basement of the Demerara Plateau, offshore French Guiana and Suriname. According to plate reconstructions, a single hotspot may be responsible for the magmatic formation of (1) both the Demerara Plateau (between 180 and 170 Ma) and the Guinea Plateau (circa 165 Ma) during the end of the Jurassic rifting of the Central Atlantic; (2) both Sierra Leone and Ceara Rises (mainly from 76 to 68 Ma) during the upper Cretaceous oceanic spreading of the Equatorial Atlantic ocean; (3) the Bathymetrists seamount chain since the upper Cretaceous. The present-day location of the inferred Sierra Leone hotspot should be 100 km west of the Knipovich Seamount. |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00628/74034/73363.pdf |
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| Mahan, Brandon; Moynier, Frederic; Siebert, Julien; Gueguen, Bleuenn; Agranier, Arnaud; Pringle, Emily A.; Bollard, Jean; Connelly, James N.; Bizzarro, Martin. |
| Chondrites and their main components, chondrules, are our guides into the evolution of the Solar System. Investigating the history of chondrules, including their volatile element history and the prevailing conditions of their formation, has implications not only for the understanding of chondrule formation and evolution but for that of larger bodies such as the terrestrial planets. Here we have determined the bulk chemical composition-rare earth, refractory, main group, and volatile element contents-of a suite of chondrules previously dated using the Pb-Pb system. The volatile element contents of chondrules increase with time from similar to 1 My after Solar System formation, likely the result of mixing with a volatile-enriched component during chondrule... |
| Tipo: Text |
Palavras-chave: Cosmochemistry; Planetary formation; Pebble accretion; Solar System evolution; Meteorites. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00638/74979/75756.pdf |
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| Brugier, Yann-aurélien; Barrat, Jean-alix; Gueguen, Bleuenn; Agranier, Arnaud; Yamaguchi, Akira; Bischoff, Addi. |
| The Ureilite Parent Body (UPB) was a C-rich planetary embryo disrupted by impact. Ureilites are fragments of the UPB mantle and among the most numerous achondrites. Zinc isotopic data are presented for 26 unbrecciated ureilites and a trachyandesite (ALM-A) from the same parent body. The δ66Zn values of ureilites range from 0.40 to 2.71 ‰ including literature results. Zinc isotopic compositions do not correlate with the compositions of olivine cores, with C and O isotopic compositions, with Zn abundances, nor with shock grades. The wide range of δ66Zn displayed by the ureilites is chiefly explained by evaporation processes that took place during the catastrophic breakup of the UPB. During breakup, the high temperatures of the UPB mantle allowed Zn to... |
| Tipo: Text |
Palavras-chave: Ureilite; Zinc isotopic composition; Isotope fractionation; Shock. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00472/58335/60889.pdf |
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