2022
|
Podda, O., Tissandier, L., Laplace, A., Deloule, E. Solubility of uranium oxide in ternary aluminosilicate glass melts (Article de journal) Dans: Journal of Non-Crystalline Solids, vol. 595, p. 121845, 2022. @article{Podda_etal2022,
title = {Solubility of uranium oxide in ternary aluminosilicate glass melts},
author = {O. Podda and L. Tissandier and A. Laplace and E. Deloule},
doi = {10.1016/j.jnoncrysol.2022.121845},
year = {2022},
date = {2022-01-01},
journal = {Journal of Non-Crystalline Solids},
volume = {595},
pages = {121845},
abstract = {Uranium solubility was measured in melts belonging to the CaO-Al2O3-SiO2 (CAS) and MgO-Al2O3-SiO2 (MAS) systems using the Pt wire loop technique, enabling independent control of the temperature (1400 \^{a}¦C), glass composition, and oxygen fugacity (-16.1\<log(fO2)\<-0.7). The low sample masses allowed the equilibrium state to be reached quickly and rapid quenching of the glasses was performed in order to immobilize each system as close as possible to the molten state. The compositions of the different quenched glasses were analyzed by EDS. Uranium solubility decreased with decreasing oxygen fugacity, highlighting the lower solubility of uranium at reduced oxidation states. For each system, uranium solubility was constant from log(fO2)\<-9.7. Moreover, different uranium behavior was evidenced between the two ternary systems. Modification of the Al content affected only uranium solubility in the CAS compositions, while uranium volatilization for oxidizing conditions was noted in the MAS system. This difference in behavior may be attributed to structural changes and probably to the variable proportions of [5]Al in each glass system.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Uranium solubility was measured in melts belonging to the CaO-Al2O3-SiO2 (CAS) and MgO-Al2O3-SiO2 (MAS) systems using the Pt wire loop technique, enabling independent control of the temperature (1400 â¦C), glass composition, and oxygen fugacity (-16.1<log(fO2)<-0.7). The low sample masses allowed the equilibrium state to be reached quickly and rapid quenching of the glasses was performed in order to immobilize each system as close as possible to the molten state. The compositions of the different quenched glasses were analyzed by EDS. Uranium solubility decreased with decreasing oxygen fugacity, highlighting the lower solubility of uranium at reduced oxidation states. For each system, uranium solubility was constant from log(fO2)<-9.7. Moreover, different uranium behavior was evidenced between the two ternary systems. Modification of the Al content affected only uranium solubility in the CAS compositions, while uranium volatilization for oxidizing conditions was noted in the MAS system. This difference in behavior may be attributed to structural changes and probably to the variable proportions of [5]Al in each glass system. |
2021
|
Boulliung, J., Dalou, C., Tissandier, L., Füri, E., Marrocchi, Y. Nitrogen diffusion in silicate melts under reducing conditions (Article de journal) Dans: American Mineralogist, vol. 106, p. 662–666, 2021. @article{Boulliung_etal2021,
title = {Nitrogen diffusion in silicate melts under reducing conditions},
author = {J. Boulliung and C. Dalou and L. Tissandier and E. F\"{u}ri and Y. Marrocchi},
doi = {10.2138/am-2021-7799CCBYNCND},
year = {2021},
date = {2021-01-01},
journal = {American Mineralogist},
volume = {106},
pages = {662--666},
abstract = {The behavior of nitrogen during magmatic degassing and the potential kinetic fractionation between N and other volatile species (H, C, O, noble gases) are poorly known due to the paucity of N diffusion data in silicate melts. To better constrain N mobility during magmatic processes, we investigated N diffusion in silicate melts under reducing conditions. We developed uniaxial diffusion experiments at 1 atm, 1425 textdegreeC, and under nominally anhydrous reducing conditions (fO2 ≤ IW-5.1, where IW is oxygen fugacity, fO2, reported in log units relative to the iron-wüstite buffer), in which N was chemically dissolved in silicate melts as nitride (N3--). Although several experimental designs were tested (platinum, amorphous graphite, and compacted graphite crucibles), only N diffusion experiments at IW-8 in compacted graphite crucibles for simplified basaltic andesite melts were successful. Measured N diffusivity (DN) is on the order of 5.3 textpm 1.5 texttimes 10--12 m2 s--1, two orders of magnitude lower than N chemical diffusion in soda-lime silicate melts (Frischat et al. 1978). This difference suggests that nitride diffusivity increases with an increasing degree of melt depolymerization. The dependence of N3-- diffusion on melt composition is greater than that of Ar. Furthermore, N3-- diffusion in basaltic-andesitic melts is significantly slower than that of Ar in similarly polymerized andesitic-tholeiitic melts at magmatic temperatures (1400--1450 textdegreeC ; Nowak et al. 2004). This implies that N/Ar ratios can be fractionated during reducing magmatic processes, such as during early Earthtextquoterights magma ocean stages.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The behavior of nitrogen during magmatic degassing and the potential kinetic fractionation between N and other volatile species (H, C, O, noble gases) are poorly known due to the paucity of N diffusion data in silicate melts. To better constrain N mobility during magmatic processes, we investigated N diffusion in silicate melts under reducing conditions. We developed uniaxial diffusion experiments at 1 atm, 1425 textdegreeC, and under nominally anhydrous reducing conditions (fO2 ≤ IW-5.1, where IW is oxygen fugacity, fO2, reported in log units relative to the iron-wüstite buffer), in which N was chemically dissolved in silicate melts as nitride (N3--). Although several experimental designs were tested (platinum, amorphous graphite, and compacted graphite crucibles), only N diffusion experiments at IW-8 in compacted graphite crucibles for simplified basaltic andesite melts were successful. Measured N diffusivity (DN) is on the order of 5.3 textpm 1.5 texttimes 10--12 m2 s--1, two orders of magnitude lower than N chemical diffusion in soda-lime silicate melts (Frischat et al. 1978). This difference suggests that nitride diffusivity increases with an increasing degree of melt depolymerization. The dependence of N3-- diffusion on melt composition is greater than that of Ar. Furthermore, N3-- diffusion in basaltic-andesitic melts is significantly slower than that of Ar in similarly polymerized andesitic-tholeiitic melts at magmatic temperatures (1400--1450 textdegreeC ; Nowak et al. 2004). This implies that N/Ar ratios can be fractionated during reducing magmatic processes, such as during early Earthtextquoterights magma ocean stages. |
2020
|
Boulliung, J., Füri, E., Dalou, C., Tissandier, L., Zimmermann, L., Marrocchi, Y. Oxygen fugacity and melt composition controls on nitrogen solubility in silicate melts (Article de journal) Dans: Geochimica et Cosmochimica Acta, vol. 284, p. 120–133, 2020. @article{Boulliung_etal2020,
title = {Oxygen fugacity and melt composition controls on nitrogen solubility in silicate melts},
author = {J. Boulliung and E. F\"{u}ri and C. Dalou and L. Tissandier and L. Zimmermann and Y. Marrocchi},
doi = {10.1016/j.gca.2020.06.020},
year = {2020},
date = {2020-01-01},
journal = {Geochimica et Cosmochimica Acta},
volume = {284},
pages = {120--133},
abstract = {Knowledge of N solubility in silicate melts is key for understanding the origin of terrestrial N and the distribution andexchanges of N between the atmosphere, the silicate magma ocean, and the core forming metal. To place constraints onthe incorporation mechanism(s) of N in silicate melts, we investigated the effect of the oxygen fugacity (fO2) and melt com-position on the N solubility through N equilibration experiments at atmospheric pressure and high temperature (1425textdegreeC).Oxygen fugacity (expressed in log units relative to the iron-wu ̈stite buffer, IW) was varied from IW --8 to IW +4.1, and meltcompositions covered a wide range of polymerization degrees, defined by the NBO/T ratio (the number of non-bridging oxy-gen atoms per tetrahedrally coordinated cations). The N contents of the quenched run products (silicate glasses) were ana-lyzed byin-situsecondary ion mass spectrometry and bulk CO2laser extraction static mass spectrometry, yielding resultsthat are in excellent agreement even for N concentrations at the (sub-)ppm level. The data obtained here highlight the fun-damental control offO2and the degree of polymerization of the silicate melt on N solubility. Under highly reduced conditions(fO2= IW --8), the N solubility increased with increasing NBO/T from 17.4 textpm 0.4 ppm.atm-1/2in highly polymerized melts(NBO/T = 0) to 6710 textpm 102 ppm.atm-1/2in depolymerized melts (NBO/T˜2.0). In contrast, under less reducing conditions(fO2\> IW --3.4), N solubility is very low (≤2 ppm.atm-1/2), irrespective of the NBO/T value. Our results provide constraintson N solubility in enstatite chondrite melts and in the shallow part of a planetary magma ocean. The nitrogen storage capacityof an enstatite chondrite melt, which may approximate that of planetesimals that accreted and melted early in the inner SolarSystem, varies between ˜60 and ˜6000 ppm at IW --5.1 and IW --8, respectively. In contrast, a mafic to ultra-mafic magmaocean could have incorporated ˜0.3 ppm to ˜35 ppm N under thefO2conditions inferred for the young Earth (i.e., IW --5 toIW). The N storage capacity of a reduced magma ocean (i.e., IW --3.4 to IW) in equilibrium with a N-rich atmosphere is ≤1 ppm, comparable to the N content of the present-day mantle. However under more reducing conditions (i.e., IW --5 toIW --4), the N storage capacity is significantly higher (˜35 ppm) ; in this case, Earth would have lost N to the atmosphereand/or N would have been transported into and stored within its deep interior (i.e., deep mantle, core).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Knowledge of N solubility in silicate melts is key for understanding the origin of terrestrial N and the distribution andexchanges of N between the atmosphere, the silicate magma ocean, and the core forming metal. To place constraints onthe incorporation mechanism(s) of N in silicate melts, we investigated the effect of the oxygen fugacity (fO2) and melt com-position on the N solubility through N equilibration experiments at atmospheric pressure and high temperature (1425textdegreeC).Oxygen fugacity (expressed in log units relative to the iron-wu ̈stite buffer, IW) was varied from IW --8 to IW +4.1, and meltcompositions covered a wide range of polymerization degrees, defined by the NBO/T ratio (the number of non-bridging oxy-gen atoms per tetrahedrally coordinated cations). The N contents of the quenched run products (silicate glasses) were ana-lyzed byin-situsecondary ion mass spectrometry and bulk CO2laser extraction static mass spectrometry, yielding resultsthat are in excellent agreement even for N concentrations at the (sub-)ppm level. The data obtained here highlight the fun-damental control offO2and the degree of polymerization of the silicate melt on N solubility. Under highly reduced conditions(fO2= IW --8), the N solubility increased with increasing NBO/T from 17.4 textpm 0.4 ppm.atm-1/2in highly polymerized melts(NBO/T = 0) to 6710 textpm 102 ppm.atm-1/2in depolymerized melts (NBO/T˜2.0). In contrast, under less reducing conditions(fO2> IW --3.4), N solubility is very low (≤2 ppm.atm-1/2), irrespective of the NBO/T value. Our results provide constraintson N solubility in enstatite chondrite melts and in the shallow part of a planetary magma ocean. The nitrogen storage capacityof an enstatite chondrite melt, which may approximate that of planetesimals that accreted and melted early in the inner SolarSystem, varies between ˜60 and ˜6000 ppm at IW --5.1 and IW --8, respectively. In contrast, a mafic to ultra-mafic magmaocean could have incorporated ˜0.3 ppm to ˜35 ppm N under thefO2conditions inferred for the young Earth (i.e., IW --5 toIW). The N storage capacity of a reduced magma ocean (i.e., IW --3.4 to IW) in equilibrium with a N-rich atmosphere is ≤1 ppm, comparable to the N content of the present-day mantle. However under more reducing conditions (i.e., IW --5 toIW --4), the N storage capacity is significantly higher (˜35 ppm) ; in this case, Earth would have lost N to the atmosphereand/or N would have been transported into and stored within its deep interior (i.e., deep mantle, core). |
Roskosz, M., Amet, Q., Fitoussi, C., Dauphas, N., Bourdon, B., Tissandier, L., Hu, M. Y., Said, A., Alatas, A., Alp, E. E. Redox and structural controls on tin isotopic fractionations among magmas (Article de journal) Dans: Geochimica et Cosmochimica Acta, vol. 268, p. 42–55, 2020. @article{Roskosz_etal2020,
title = {Redox and structural controls on tin isotopic fractionations among magmas},
author = {M. Roskosz and Q. Amet and C. Fitoussi and N. Dauphas and B. Bourdon and L. Tissandier and M. Y. Hu and A. Said and A. Alatas and E. E. Alp},
doi = {10.1016/j.gca.2019.09.036},
year = {2020},
date = {2020-01-01},
journal = {Geochimica et Cosmochimica Acta},
volume = {268},
pages = {42--55},
abstract = {Recent analytical developments have made possible the determination of the isotopic composition of tin in igneous rocks. In order to establish a framework to interpret the mass-dependent tin isotopic signatures of planetary materials, seven geologically-relevant silicate glasses (basalt, rhyolite, enstatite and anorthite glasses) were synthesized with moderate amounts of 119Sn (on the order of a weight percent). Redox conditions were controlled during sample synthesis to set the redox ratio (Sn2+/Sntot) from stannous (Sn2+) to stannic (Sn4+) glasses. The mean force constants of tin bonds in these glasses were determined by synchrotron nuclear resonant inelastic X-ray scattering (NRIXS) in order to determine the reduced isotopic partition function ratios ($beta$-factors) of these glasses. Clues on the coordination chemistry and the valence state of tin in these glasses were also derived from synchrotron Mossbauer spectroscopy (SMS). The force constants of tin drastically increases from Sn2+-bearing to Sn4+-bearing glasses and varies significantly with the glass composition at a given redox state. The average coordination number of tin likely controls these variations with glass composition as suggested by SMS results. It is concluded that large isotope fractionation is expected between materials containing Sn2+ and Sn4+ respectively even at magmatic temperatures and that the coordination chemistry of tin in silicates strongly affect its isotope partitioning behavior. Our experimental data are finally used to interpret available Sn isotope data collected in terrestrial rocks. The incompatible behavior of Sn4+ in mantle minerals leads to a enrichment in heavy isotopes in mantle melts and to the depletion in heavy isotopes in solid residues of melting with a magnitude consistent with the isotope fractionation between Sn2+ and Sn4+ predicted by NRIXS data. Finally, we show that during fractional crystallization of basalt and considering the effect of tin coordination number in minerals and melts, the partitioning of Sn4+ into ilmenite leads to an enrichment in light isotopes in the residual melt.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Recent analytical developments have made possible the determination of the isotopic composition of tin in igneous rocks. In order to establish a framework to interpret the mass-dependent tin isotopic signatures of planetary materials, seven geologically-relevant silicate glasses (basalt, rhyolite, enstatite and anorthite glasses) were synthesized with moderate amounts of 119Sn (on the order of a weight percent). Redox conditions were controlled during sample synthesis to set the redox ratio (Sn2+/Sntot) from stannous (Sn2+) to stannic (Sn4+) glasses. The mean force constants of tin bonds in these glasses were determined by synchrotron nuclear resonant inelastic X-ray scattering (NRIXS) in order to determine the reduced isotopic partition function ratios ($beta$-factors) of these glasses. Clues on the coordination chemistry and the valence state of tin in these glasses were also derived from synchrotron Mossbauer spectroscopy (SMS). The force constants of tin drastically increases from Sn2+-bearing to Sn4+-bearing glasses and varies significantly with the glass composition at a given redox state. The average coordination number of tin likely controls these variations with glass composition as suggested by SMS results. It is concluded that large isotope fractionation is expected between materials containing Sn2+ and Sn4+ respectively even at magmatic temperatures and that the coordination chemistry of tin in silicates strongly affect its isotope partitioning behavior. Our experimental data are finally used to interpret available Sn isotope data collected in terrestrial rocks. The incompatible behavior of Sn4+ in mantle minerals leads to a enrichment in heavy isotopes in mantle melts and to the depletion in heavy isotopes in solid residues of melting with a magnitude consistent with the isotope fractionation between Sn2+ and Sn4+ predicted by NRIXS data. Finally, we show that during fractional crystallization of basalt and considering the effect of tin coordination number in minerals and melts, the partitioning of Sn4+ into ilmenite leads to an enrichment in light isotopes in the residual melt. |
2019
|
Giuliani, G., Pignatelli, I., Lheur, C., Feneyrol, J., Claiser, N., Tissandier, L., Fallick, A. E., Boyce, A., Ohnenstetter, D. Les zo"isites de Canari (France) et Merelani (Tanzanie) : similitudes et différences (Article de journal) Dans: Le R`egne Minéral, vol. 149, p. 20–51, 2019. @article{Giuliani_etal2019_3,
title = {Les zo"isites de Canari (France) et Merelani (Tanzanie) : similitudes et diff\'{e}rences},
author = {G. Giuliani and I. Pignatelli and C. Lheur and J. Feneyrol and N. Claiser and L. Tissandier and A. E. Fallick and A. Boyce and D. Ohnenstetter},
year = {2019},
date = {2019-01-01},
journal = {Le R`egne Min\'{e}ral},
volume = {149},
pages = {20--51},
abstract = {La formation des zo"isites `a Cr (textpmV) de Canari (Corse) et `a V (textpmCr) de Merelani (Tanzanie) est le r\'{e}sultat respectif dtextquoterightun \'{e}pisode m\'{e}tamorphique dans le faci`es Schiste vert, de moyenne `a basse temp\'{e}rature (480-300textdegreeC). Ces zo"isites se forment au cours de phases tectono-m\'{e}tamorphiques tardives et elles se localisent dans des syst`emes de fissures, de veines, de veinules et/ou de poches. La zo"isite corse est associ\'{e}e `a ltextquoteright\'{e}pisode tectonique extensif du Tertiaire qui affecta la s\'{e}rie ophiolitique du Cap Corse. La zo"isite tanzanienne est n\'{e}oprot\'{e}rozo"ique et reli\'{e}e `a la phase de r\'{e}tromorphose qui affecta la s\'{e}rie m\'{e}tas\'{e}dimentaire de Merelani. `Altextquoterightancienne mine dtextquoterightasbeste de Canari, la zo"isite se trouve dans des m\'{e}tagabbros, et `a Merelani, dans des intercalations de roches calco-silicat\'{e}es et de m\'{e}ta-\'{e}vaporites au sein de gneiss graphiteux. Les sources du vanadium (V) et chrome (Cr) pour ces zo"isites sont dtextquoterightorigine mantellique : les m\'{e}tagabbros `a Canari, et `a Merelani, une s\'{e}rie m\'{e}tas\'{e}dimentaire o`u Cr et V proviennent de ltextquoteright\'{e}rosion de formations mafiques-ultramafiques et par la suite, du d\'{e}p^ot dtextquoterightargiles `a Cr-V dans un bassin s\'{e}dimentaire de ltextquoterightOc\'{e}an mozambicain, qui est m\'{e}tamorphis\'{e} au N\'{e}oprot\'{e}rozo"ique, au cours de ltextquoterightorogen`ese de ltextquoterightAfrique de ltextquoterightEst. Les associations notamment de min\'{e}raux calciques et magn\'{e}siens soit comme paragen`ese, soit comme min\'{e}raux inclus dans les zo"isites sont dtextquoterightautres points min\'{e}ralogiques communs. Les param`etres de maille calcul\'{e}s `a partir dtextquoterightune \'{e}tude de rayons X sur un cristal de Canari confirment d\'{e}finitivement la pr\'{e}sence de zo"isite au Cap Corse. Par ailleurs, les deux zo"isites de couleur verte poss`edent de faibles (Canari) `a extr^emement faibles (Merelani) teneurs en fer. Les diff\'{e}rences sont majeures en ce qui concerne : (1) la nature du protolithe1 supportant la min\'{e}ralisation ; (2) les cristaux en terme de dimension et de couleur qui sont de petite taille, transparents `a translucides, faiblement color\'{e}s `a Canari (tr`es rarement avec une belle teinte verte), et de grande taille et fortement color\'{e}s `a Merelani (avec une v\'{e}ritable zo"isite verte). Canari est une occurrence min\'{e}ralogique reconnue alors que Merelani est un gisement de zo"isite gemme `a haute valeur \'{e}conomique ; (3) la composition des fluides, aqueux (H2O) `a Canari, et sulfur\'{e}s (H2S-S8) `a Merelani, ainsi que les m\'{e}canismes chimiques et thermodynamiques responsables de la formation de la zo"isite ; (4) les compositions isotopiques de ltextquoterightoxyg`ene qui sont tr`es contrast\'{e}es. Le traitement thermique r\'{e}alis\'{e} sur la zo"isite de Canari, de couleur vert tr`es clair, entre 400 et 700textdegreeC pendant six heures, ntextquoterighta pas mis en \'{e}vidence de changement de couleur, ph\'{e}nom`ene d\'{e}crit \'{e}galement pour la zo"isite verte de Merelani.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
La formation des zo"isites `a Cr (textpmV) de Canari (Corse) et `a V (textpmCr) de Merelani (Tanzanie) est le résultat respectif dtextquoterightun épisode métamorphique dans le faci`es Schiste vert, de moyenne `a basse température (480-300textdegreeC). Ces zo"isites se forment au cours de phases tectono-métamorphiques tardives et elles se localisent dans des syst`emes de fissures, de veines, de veinules et/ou de poches. La zo"isite corse est associée `a ltextquoterightépisode tectonique extensif du Tertiaire qui affecta la série ophiolitique du Cap Corse. La zo"isite tanzanienne est néoprotérozo"ique et reliée `a la phase de rétromorphose qui affecta la série métasédimentaire de Merelani. `Altextquoterightancienne mine dtextquoterightasbeste de Canari, la zo"isite se trouve dans des métagabbros, et `a Merelani, dans des intercalations de roches calco-silicatées et de méta-évaporites au sein de gneiss graphiteux. Les sources du vanadium (V) et chrome (Cr) pour ces zo"isites sont dtextquoterightorigine mantellique : les métagabbros `a Canari, et `a Merelani, une série métasédimentaire o`u Cr et V proviennent de ltextquoterightérosion de formations mafiques-ultramafiques et par la suite, du dép^ot dtextquoterightargiles `a Cr-V dans un bassin sédimentaire de ltextquoterightOcéan mozambicain, qui est métamorphisé au Néoprotérozo"ique, au cours de ltextquoterightorogen`ese de ltextquoterightAfrique de ltextquoterightEst. Les associations notamment de minéraux calciques et magnésiens soit comme paragen`ese, soit comme minéraux inclus dans les zo"isites sont dtextquoterightautres points minéralogiques communs. Les param`etres de maille calculés `a partir dtextquoterightune étude de rayons X sur un cristal de Canari confirment définitivement la présence de zo"isite au Cap Corse. Par ailleurs, les deux zo"isites de couleur verte poss`edent de faibles (Canari) `a extr^emement faibles (Merelani) teneurs en fer. Les différences sont majeures en ce qui concerne : (1) la nature du protolithe1 supportant la minéralisation ; (2) les cristaux en terme de dimension et de couleur qui sont de petite taille, transparents `a translucides, faiblement colorés `a Canari (tr`es rarement avec une belle teinte verte), et de grande taille et fortement colorés `a Merelani (avec une véritable zo"isite verte). Canari est une occurrence minéralogique reconnue alors que Merelani est un gisement de zo"isite gemme `a haute valeur économique ; (3) la composition des fluides, aqueux (H2O) `a Canari, et sulfurés (H2S-S8) `a Merelani, ainsi que les mécanismes chimiques et thermodynamiques responsables de la formation de la zo"isite ; (4) les compositions isotopiques de ltextquoterightoxyg`ene qui sont tr`es contrastées. Le traitement thermique réalisé sur la zo"isite de Canari, de couleur vert tr`es clair, entre 400 et 700textdegreeC pendant six heures, ntextquoterighta pas mis en évidence de changement de couleur, phénom`ene décrit également pour la zo"isite verte de Merelani. |
Vacher, L. G., Truche, L., Faure, F., Tissandier, L., Mosser-Ruck, R., Marrocchi, Y. Deciphering the conditions of tochilinite and cronstedtite formation in CM chondrites from low temperature hydrothermal experiments (Article de journal) Dans: Meteoritics & Planetary Science, vol. 54, p. 1870–1889, 2019. @article{Vacher_etal2019_2,
title = {Deciphering the conditions of tochilinite and cronstedtite formation in CM chondrites from low temperature hydrothermal experiments},
author = {L. G. Vacher and L. Truche and F. Faure and L. Tissandier and R. Mosser-Ruck and Y. Marrocchi},
doi = {10.1111/maps.13317},
year = {2019},
date = {2019-01-01},
journal = {Meteoritics \& Planetary Science},
volume = {54},
pages = {1870--1889},
abstract = {Tochilinite/cronstedtite intergrowths are commonly observed as alteration products in CM chondrite matrices, but the conditions under which they formed are still largely underconstrained due to their scarcity in terrestrial environments. Here, we report low temperature (80 textdegreeC) anoxic hydrothermal experiments using starting assemblages similar to the constituents of the matrices of the most pristine CM chondrite and S-rich and S-free fluids. Cronstedtite crystals formed only in S-free experiments under circumneutral conditions with the highest Fe/Si ratios. Fe-rich tochilinite with chemical and structural characteristics similar to chondritic tochilinite was observed in S-bearing experiments. We observed a positive correlation between the Mg content in the hydroxide layer of synthetic tochilinite and temperature, suggesting that the composition of tochilinite is a proxy for the alteration temperature in CM chondrites. Using this relation, we estimate the mean precipitation temperatures of tochilinite to be 120--160 textdegreeC for CM chondrites. Given the different temperature ranges of tochilinite and cronstedtite in our experiments, we propose that Fe-rich tochilinite crystals resulted from the alteration of metal beads under S-bearing alkaline conditions at T = 120--160 textdegreeC followed by cronstedtite crystals formed by the reaction of matrix amorphous silicates, metal beads, and water at a low temperature (50--120 textdegreeC).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Tochilinite/cronstedtite intergrowths are commonly observed as alteration products in CM chondrite matrices, but the conditions under which they formed are still largely underconstrained due to their scarcity in terrestrial environments. Here, we report low temperature (80 textdegreeC) anoxic hydrothermal experiments using starting assemblages similar to the constituents of the matrices of the most pristine CM chondrite and S-rich and S-free fluids. Cronstedtite crystals formed only in S-free experiments under circumneutral conditions with the highest Fe/Si ratios. Fe-rich tochilinite with chemical and structural characteristics similar to chondritic tochilinite was observed in S-bearing experiments. We observed a positive correlation between the Mg content in the hydroxide layer of synthetic tochilinite and temperature, suggesting that the composition of tochilinite is a proxy for the alteration temperature in CM chondrites. Using this relation, we estimate the mean precipitation temperatures of tochilinite to be 120--160 textdegreeC for CM chondrites. Given the different temperature ranges of tochilinite and cronstedtite in our experiments, we propose that Fe-rich tochilinite crystals resulted from the alteration of metal beads under S-bearing alkaline conditions at T = 120--160 textdegreeC followed by cronstedtite crystals formed by the reaction of matrix amorphous silicates, metal beads, and water at a low temperature (50--120 textdegreeC). |
2018
|
Amalberti, J., Burnard, P., Tissandier, L., Laporte, D. The diffusion coefficients of noble gases (He-Ar) in a synthetic basaltic liquid: One-dimensional diffusion experiments (Article de journal) Dans: Chemical Geology, vol. 480, p. 35–43, 2018. @article{Amalberti_etal2018,
title = {The diffusion coefficients of noble gases (He-Ar) in a synthetic basaltic liquid: One-dimensional diffusion experiments},
author = {J. Amalberti and P. Burnard and L. Tissandier and D. Laporte},
doi = {10.1016/j.chemgeo.2017.05.017},
year = {2018},
date = {2018-01-01},
journal = {Chemical Geology},
volume = {480},
pages = {35--43},
abstract = {Diffusion coefficients of noble gases in silicate liquids are poorly known, and, as a result, it is difficult to quantify the importance of kinetic fractionation of noble gas abundances and isotopic compositions during magmatic processes. Nevertheless, diffusive fractionation has been invoked to explain noble gas signatures in MORBs and OIBs, with important implications for magma degassing and noble gas mantle geochemistry. In order to investigate the diffusion of noble gases in magmas, we developed an experimental protocol based on uniaxial diffusion of He and Ar through a column of synthetic basaltic liquid in a Pt tube. At the end of the experiment, the column of silicate liquid was rapidly quenched to a glass recording the diffusion profile. The glass cylinder was cut into a series of slices, which were analyzed for noble gases by traditional noble gas mass spectrometry following total gas extraction by fusion. Using this protocol, we measured He and Ar diffusivities in CMAS glass G1 (50 mol% SiO2, 9 mol% Al2O3,16 mol% MgO, 25 mol% CaO) at temperatures of 1673 K and 1823 K: DHe= 2.75 textpm 0.25texttimes10−6 cm2textperiodcentereds−1 (T =1673 K); DHe =4.77 textpm 0.42 texttimes10−6 cm2textperiodcentereds−1 (T =1823 K); and DAr =9.3 textpm 1.3 texttimes10−7 cm2textperiodcentereds−1 (T =1673 K). Combining these new high temperature data with diffusion coefficients measured on the same composition just above the glass transition temperature, we determined the activation energy Ea and the preexponential factor D0 for He and Ar diffusion in silicate liquids: D0 = 1.72 textpm 0.9texttimes10−2 cm2textperiodcentereds−1 and Ea =136.5 textpm 3.2 kJ/mol for Ar; D0 =1.8 textpm 0.5texttimes10−4 cm2textperiodcentereds−1 and Ea =57.6 textpm 1.5 kJ/mol for He. Because He and Ar have very different activation energies for diffusion in the liquid state, the ratio DHe/DAr is strongly sensitive to temperature, decreasing from 145 at the glass transition temperature (1005 K) to 2 at 1823 K. The implication is that the kinetic fractionation of He relative to Ar in magmas is likely to be more important during the cooling stages than during the earlier, high temperature stages of magmatic history.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Diffusion coefficients of noble gases in silicate liquids are poorly known, and, as a result, it is difficult to quantify the importance of kinetic fractionation of noble gas abundances and isotopic compositions during magmatic processes. Nevertheless, diffusive fractionation has been invoked to explain noble gas signatures in MORBs and OIBs, with important implications for magma degassing and noble gas mantle geochemistry. In order to investigate the diffusion of noble gases in magmas, we developed an experimental protocol based on uniaxial diffusion of He and Ar through a column of synthetic basaltic liquid in a Pt tube. At the end of the experiment, the column of silicate liquid was rapidly quenched to a glass recording the diffusion profile. The glass cylinder was cut into a series of slices, which were analyzed for noble gases by traditional noble gas mass spectrometry following total gas extraction by fusion. Using this protocol, we measured He and Ar diffusivities in CMAS glass G1 (50 mol% SiO2, 9 mol% Al2O3,16 mol% MgO, 25 mol% CaO) at temperatures of 1673 K and 1823 K: DHe= 2.75 textpm 0.25texttimes10−6 cm2textperiodcentereds−1 (T =1673 K); DHe =4.77 textpm 0.42 texttimes10−6 cm2textperiodcentereds−1 (T =1823 K); and DAr =9.3 textpm 1.3 texttimes10−7 cm2textperiodcentereds−1 (T =1673 K). Combining these new high temperature data with diffusion coefficients measured on the same composition just above the glass transition temperature, we determined the activation energy Ea and the preexponential factor D0 for He and Ar diffusion in silicate liquids: D0 = 1.72 textpm 0.9texttimes10−2 cm2textperiodcentereds−1 and Ea =136.5 textpm 3.2 kJ/mol for Ar; D0 =1.8 textpm 0.5texttimes10−4 cm2textperiodcentereds−1 and Ea =57.6 textpm 1.5 kJ/mol for He. Because He and Ar have very different activation energies for diffusion in the liquid state, the ratio DHe/DAr is strongly sensitive to temperature, decreasing from 145 at the glass transition temperature (1005 K) to 2 at 1823 K. The implication is that the kinetic fractionation of He relative to Ar in magmas is likely to be more important during the cooling stages than during the earlier, high temperature stages of magmatic history. |
Bekaert, D. V., Derenne, S., Tissandier, L., Marrocchi, Y., Charnoz, S., Anquetil, C., Marty, B. High-temperature ionization-induced synthesis of biologically relevant molecules in the protosolar nebula (Article de journal) Dans: Astrophysical Journal, vol. 859, no. 142, 2018. @article{Bekaert_etal2018_4,
title = {High-temperature ionization-induced synthesis of biologically relevant molecules in the protosolar nebula},
author = {D. V. Bekaert and S. Derenne and L. Tissandier and Y. Marrocchi and S. Charnoz and C. Anquetil and B. Marty},
doi = {10.3847/1538-4357/aabe7a},
year = {2018},
date = {2018-01-01},
journal = {Astrophysical Journal},
volume = {859},
number = {142},
abstract = {Biologically relevant molecules (hereafter biomolecules) have been commonly observed in extraterrestrial samples, but the mechanisms accounting for their synthesis in space are not well understood. While electron-driven production of organic solids from gas mixtures reminiscent of the photosphere of the protosolar nebula (PSN; i.e., dominated by CO--N2--H2) successfully reproduced key specific features of the chondritic insoluble organic matter (e.g., elementary and isotopic signatures of chondritic noble gases), the molecular diversity of organic materials has never been investigated. Here, we report that a large range of biomolecules detected in meteorites and comets can be synthesized under conditions typical of the irradiated gas phase of the PSN at temperatures=800 K. Our results suggest that organic materials---including biomolecules---produced within the photosphere would have been widely dispersed in the protoplanetary disk through turbulent diffusion, providing a mechanism for the distribution of organic meteoritic precursors prior to any thermal/photoprocessing and subsequent modification bysecondary parent body processes. Using a numerical model of dust transport in a turbulent disk, we propose that organic materials produced in the photosphere of the disk would likely be associated with small dust particles, which are coupled to the motion of gas within the disk and therefore preferentially lofted into the upper layers of the disk where organosynthesis occurs.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Biologically relevant molecules (hereafter biomolecules) have been commonly observed in extraterrestrial samples, but the mechanisms accounting for their synthesis in space are not well understood. While electron-driven production of organic solids from gas mixtures reminiscent of the photosphere of the protosolar nebula (PSN; i.e., dominated by CO--N2--H2) successfully reproduced key specific features of the chondritic insoluble organic matter (e.g., elementary and isotopic signatures of chondritic noble gases), the molecular diversity of organic materials has never been investigated. Here, we report that a large range of biomolecules detected in meteorites and comets can be synthesized under conditions typical of the irradiated gas phase of the PSN at temperatures=800 K. Our results suggest that organic materials---including biomolecules---produced within the photosphere would have been widely dispersed in the protoplanetary disk through turbulent diffusion, providing a mechanism for the distribution of organic meteoritic precursors prior to any thermal/photoprocessing and subsequent modification bysecondary parent body processes. Using a numerical model of dust transport in a turbulent disk, we propose that organic materials produced in the photosphere of the disk would likely be associated with small dust particles, which are coupled to the motion of gas within the disk and therefore preferentially lofted into the upper layers of the disk where organosynthesis occurs. |
2017
|
Chevreux, P., Laplace, A., Deloule, E., Tissandier, L., Massoni, N. Hafnium solubility determination in soda-lime aluminosilicate glass (Article de journal) Dans: Journal of Non-Crystalline Solids, vol. 457, p. 13–24, 2017. @article{Chevreux_etal2017,
title = {Hafnium solubility determination in soda-lime aluminosilicate glass},
author = {P. Chevreux and A. Laplace and E. Deloule and L. Tissandier and N. Massoni},
doi = {10.1016/j.jnoncrysol.2016.11.009},
year = {2017},
date = {2017-01-01},
journal = {Journal of Non-Crystalline Solids},
volume = {457},
pages = {13--24},
abstract = {The solubility of hafnium dioxide (HfO2), used as a surrogate for tetravalent uranium, is measured in glass melts belonging to the CaO-Al2O3-SiO2 and Na2O-CaO-Al2O3-SiO2 systems, under oxidizing and reducing conditions. Two methods have been carried out to determine it and the kinetic factors controlling the HfO2 dissolution in glass melt have been investigated in order to approach equilibrium. The solubility ranges from 3 to 6.5 mol% HfO2 in aluminosilicate glasses at temperature between 1250 textdegreeC and 1400 textdegreeC, and is not affected by the redox conditions. Conversely, the solubility is modified by the melting temperature and the glass composition. The excess of alkalis or alkaline earths which are not involved in the charge balance of AlO4 tetrahedrons in the silica network appears to play a significant role. Glass homogeneity is checked by scanning electron microscopy and X-ray diffraction. HfO2, HfSiO4, Ca2HfSi4O12, Na4Hf2(SiO4)3 and Na2HfSi2O7 are metastable crystals observed in the glass melts. The stability of those crystalline phases mainly depends on the glass composition.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The solubility of hafnium dioxide (HfO2), used as a surrogate for tetravalent uranium, is measured in glass melts belonging to the CaO-Al2O3-SiO2 and Na2O-CaO-Al2O3-SiO2 systems, under oxidizing and reducing conditions. Two methods have been carried out to determine it and the kinetic factors controlling the HfO2 dissolution in glass melt have been investigated in order to approach equilibrium. The solubility ranges from 3 to 6.5 mol% HfO2 in aluminosilicate glasses at temperature between 1250 textdegreeC and 1400 textdegreeC, and is not affected by the redox conditions. Conversely, the solubility is modified by the melting temperature and the glass composition. The excess of alkalis or alkaline earths which are not involved in the charge balance of AlO4 tetrahedrons in the silica network appears to play a significant role. Glass homogeneity is checked by scanning electron microscopy and X-ray diffraction. HfO2, HfSiO4, Ca2HfSi4O12, Na4Hf2(SiO4)3 and Na2HfSi2O7 are metastable crystals observed in the glass melts. The stability of those crystalline phases mainly depends on the glass composition. |
Faure, F., Tissandier, L., Florentin, L., Devineau, K. A magmatic origin for silica-rich glass inclusions hosted in porphyritic magnesian olivines in chondrules: An experimental study (Article de journal) Dans: Geochimica et Cosmochimica Acta, vol. 204, p. 19–31, 2017. @article{Faure_etal2017,
title = {A magmatic origin for silica-rich glass inclusions hosted in porphyritic magnesian olivines in chondrules: An experimental study},
author = {F. Faure and L. Tissandier and L. Florentin and K. Devineau},
doi = {10.1016/j.gca.2017.01.034},
year = {2017},
date = {2017-01-01},
journal = {Geochimica et Cosmochimica Acta},
volume = {204},
pages = {19--31},
abstract = {Rare silica-rich glass inclusions (69 \< SiO2 \< 82 wt.%) are described within magnesian olivines of porphyritic Type IA chondrules. These glass inclusion compositions are clearly out of equilibrium with their host Mg-olivines and their presence within the olivines is generally attributed to an unclear secondary process such as a late interaction with nebular gases. We performed dynamic crystallisation experiments that demonstrate that these Si-rich glass inclusions are actually magmatic in origin and were trapped inside olivines that crystallized slowly from a magma with a CI, i.e. solar, composition. Their silicarichcompositions are the consequence of the small volumes of inclusions, which inhibit the nucleation of secondary crystalline phase (Ca-poor pyroxene) but allow olivine to continue to crystallize metastably on the walls of the inclusions. We suggestthat Si-rich glass inclusions could be the only reliable relicts of what were the first magmas of the solar system, exhibiting a CI, i.e. non-fractionated, composition.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Rare silica-rich glass inclusions (69 < SiO2 < 82 wt.%) are described within magnesian olivines of porphyritic Type IA chondrules. These glass inclusion compositions are clearly out of equilibrium with their host Mg-olivines and their presence within the olivines is generally attributed to an unclear secondary process such as a late interaction with nebular gases. We performed dynamic crystallisation experiments that demonstrate that these Si-rich glass inclusions are actually magmatic in origin and were trapped inside olivines that crystallized slowly from a magma with a CI, i.e. solar, composition. Their silicarichcompositions are the consequence of the small volumes of inclusions, which inhibit the nucleation of secondary crystalline phase (Ca-poor pyroxene) but allow olivine to continue to crystallize metastably on the walls of the inclusions. We suggestthat Si-rich glass inclusions could be the only reliable relicts of what were the first magmas of the solar system, exhibiting a CI, i.e. non-fractionated, composition. |
Florentin, L., Faure, F., Deloule, E., Tissandier, L., Gurenko, A., Lequin, D. Origin of Na in glass inclusions hosted in olivine from Allende CV3 and Jbilet Winselwan CM2: Implications for chondrule formation (Article de journal) Dans: Earth and Planetary Science Letters, vol. 474, p. 160–171, 2017. @article{Florentin_etal2017,
title = {Origin of Na in glass inclusions hosted in olivine from Allende CV3 and Jbilet Winselwan CM2: Implications for chondrule formation},
author = {L. Florentin and F. Faure and E. Deloule and L. Tissandier and A. Gurenko and D. Lequin},
doi = {10.1016/j.epsl.2017.06.038},
year = {2017},
date = {2017-01-01},
journal = {Earth and Planetary Science Letters},
volume = {474},
pages = {160--171},
abstract = {Glass inclusions trapped in Mg-rich olivines within type I chondrules from the Allende (CV3) and Jbilet Winselwan (CM2) chondrites were analyzed by EPMA (Electron Probe Microanalysis) for major elements and by SIMS (Secondary Ion Mass Spectrometry) for Cl and S (analyzed here for the first time in chondrule-hosted glass inclusions). The inclusions from Jbilet Winselwan are poor in Na2O, whereas those from Allende are Na-rich, displaying up to 8wt.% Na2O. The source of Na is a central issue in terms of chondrule origins because of the volatility of Na at high temperature. The wide scatter in Na2O contents of olivine-hosted glass inclusions from chondrules has led the community to propose that Na2O came from late interactions of chondrules with a Si/Na-rich gas. To gain new insights into the origins of the Na2O recorded in glass inclusions, heating experiments (up to 1810◦C) were performed on Allende inclusions in an effort to constrain the initial composition of the trapped melts. Our results demonstrate that sodium (although volatile) does not escape from inclusions during heating, thus confirming that glass inclusions behave as closed systems. Furthermore, heated olivines still bear inclusions containing up to 7.2wt.% of Na2O. Olivines are thought to form at temperatures at which Na is volatile. This implies that (1) Na from glass inclusions cannot come from condensation but rather results from trapping in a Na-rich environment, which implies a high pressure, as in a melting planetasimal (2) there may be two distinct origins for the sodium: an indigenous origin for the sodium trapped inside glass inclusions and a gaseous origin for the sodium recorded in mesostasis from chondrules. Consequently, these results are in favor of a planetesimal origin for olivine from chondrules.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Glass inclusions trapped in Mg-rich olivines within type I chondrules from the Allende (CV3) and Jbilet Winselwan (CM2) chondrites were analyzed by EPMA (Electron Probe Microanalysis) for major elements and by SIMS (Secondary Ion Mass Spectrometry) for Cl and S (analyzed here for the first time in chondrule-hosted glass inclusions). The inclusions from Jbilet Winselwan are poor in Na2O, whereas those from Allende are Na-rich, displaying up to 8wt.% Na2O. The source of Na is a central issue in terms of chondrule origins because of the volatility of Na at high temperature. The wide scatter in Na2O contents of olivine-hosted glass inclusions from chondrules has led the community to propose that Na2O came from late interactions of chondrules with a Si/Na-rich gas. To gain new insights into the origins of the Na2O recorded in glass inclusions, heating experiments (up to 1810◦C) were performed on Allende inclusions in an effort to constrain the initial composition of the trapped melts. Our results demonstrate that sodium (although volatile) does not escape from inclusions during heating, thus confirming that glass inclusions behave as closed systems. Furthermore, heated olivines still bear inclusions containing up to 7.2wt.% of Na2O. Olivines are thought to form at temperatures at which Na is volatile. This implies that (1) Na from glass inclusions cannot come from condensation but rather results from trapping in a Na-rich environment, which implies a high pressure, as in a melting planetasimal (2) there may be two distinct origins for the sodium: an indigenous origin for the sodium trapped inside glass inclusions and a gaseous origin for the sodium recorded in mesostasis from chondrules. Consequently, these results are in favor of a planetesimal origin for olivine from chondrules. |
Kuga, M., Cernogora, G., Marrocchi, Y., Tissandier, L., Marty, B. Processes of noble gas elemental and isotopic fractionations in plasma-produced organic solids: Cosmochemical implications (Article de journal) Dans: Geochimica et Cosmochimica Acta, vol. 217, p. 219–230, 2017. @article{Kuga_etal2017,
title = {Processes of noble gas elemental and isotopic fractionations in plasma-produced organic solids: Cosmochemical implications},
author = {M. Kuga and G. Cernogora and Y. Marrocchi and L. Tissandier and B. Marty},
doi = {10.1016/j.gca.2017.08.031},
year = {2017},
date = {2017-01-01},
journal = {Geochimica et Cosmochimica Acta},
volume = {217},
pages = {219--230},
abstract = {The main carrier of primordial heavy noble gases in chondrites is thought to be an organic phase, known as phase Q, whose precise characterization has resisted decades of investigation. The Q noble gas component shows elemental and isotopicfractionation relative to the Solar, in favor of heavy elements and isotopes. These noble gas characteristics were experimentally simulated using a plasma device called the textquotelefttextquoteleftNebulotrontextquoterighttextquoteright. In this study, we synthesized thirteen solid organic samples by electron-dissociation of CO, in which a noble gas mixture was added. The analysis of their heavy noble gas (Ar, Kr and Xe) contents and isotopic compositions reveals enrichment in the heavy noble gas isotopes and elements relative to the light ones. The isotope fractionation is mass-dependent and is consistent with a mn-type law, where n 1. Based on a plasma model, wepropose that the ambipolar diffusion of ions in the ionized CO gas medium is at the origin of the noble gas isotopic fractionation. In addition, the elemental fractionation of experimental and chondritic samples can be accounted for by the Saha law of plasma equilibrium, which does not depend on the respective noble gas masses but rather on their ionization potentials. Our results suggest that the Q noble gases were trapped into growing organic particles starting from solar gases that were fractionated in an ionized medium by ambipolar diffusion and Saha processes. This would imply that both the formation of chondritic organic matter and the trapping of noble gases took place simultaneously in the ionized areas of the protoplanetary disk.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The main carrier of primordial heavy noble gases in chondrites is thought to be an organic phase, known as phase Q, whose precise characterization has resisted decades of investigation. The Q noble gas component shows elemental and isotopicfractionation relative to the Solar, in favor of heavy elements and isotopes. These noble gas characteristics were experimentally simulated using a plasma device called the textquotelefttextquoteleftNebulotrontextquoterighttextquoteright. In this study, we synthesized thirteen solid organic samples by electron-dissociation of CO, in which a noble gas mixture was added. The analysis of their heavy noble gas (Ar, Kr and Xe) contents and isotopic compositions reveals enrichment in the heavy noble gas isotopes and elements relative to the light ones. The isotope fractionation is mass-dependent and is consistent with a mn-type law, where n 1. Based on a plasma model, wepropose that the ambipolar diffusion of ions in the ionized CO gas medium is at the origin of the noble gas isotopic fractionation. In addition, the elemental fractionation of experimental and chondritic samples can be accounted for by the Saha law of plasma equilibrium, which does not depend on the respective noble gas masses but rather on their ionization potentials. Our results suggest that the Q noble gases were trapped into growing organic particles starting from solar gases that were fractionated in an ionized medium by ambipolar diffusion and Saha processes. This would imply that both the formation of chondritic organic matter and the trapping of noble gases took place simultaneously in the ionized areas of the protoplanetary disk. |
Tissandier, L., Florentin, L., Lequin, D., Baillot, P., Faure, F. A new heating stage for high temperature/low fO2 conditions (Article de journal) Dans: Journal of Crystal Growth, vol. 458, p. 72–79, 2017. @article{Tissandier_etal2017,
title = {A new heating stage for high temperature/low fO2 conditions},
author = {L. Tissandier and L. Florentin and D. Lequin and P. Baillot and F. Faure},
doi = {10.1016/j.jcrysgro.2016.11.043},
year = {2017},
date = {2017-01-01},
journal = {Journal of Crystal Growth},
volume = {458},
pages = {72--79},
abstract = {Understanding the processes involved in the formation of intracrystalline inclusions can be valuable for both geological studies and industrial production. In view of this, we developed a new heating stage that can operate in extreme conditions. The use of tungsten as the heating material allows temperatures of over 2000 textdegreeC to be reached and also requires that experiments are run under reducing atmospheres. Small samples of metal are needed to calibrate the temperature for each experiment and the fO2 is achieved by a flow of mixed gases (CO, Ar, He). The first experiments run on this device highlight the good agreement between the different ways of estimating the temperature (by the amount of power delivered, the use of a thermocouple or by chemical composition), and a precision of textpm 20 textdegreeC is obtained for temperature determinations. As well as the homogenization of magmatic inclusions in ultramafic rocks, processes such as whisker crystal formation or transcrystalline migration of inclusions can be investigated using the new stage thanks to its very high maximum temperature and to the thermal gradients observed close to the heating wires. This new device looks to be a very promising tool that could easily be adapted for a range of studies by changing the nature and shape of the heating filaments.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Understanding the processes involved in the formation of intracrystalline inclusions can be valuable for both geological studies and industrial production. In view of this, we developed a new heating stage that can operate in extreme conditions. The use of tungsten as the heating material allows temperatures of over 2000 textdegreeC to be reached and also requires that experiments are run under reducing atmospheres. Small samples of metal are needed to calibrate the temperature for each experiment and the fO2 is achieved by a flow of mixed gases (CO, Ar, He). The first experiments run on this device highlight the good agreement between the different ways of estimating the temperature (by the amount of power delivered, the use of a thermocouple or by chemical composition), and a precision of textpm 20 textdegreeC is obtained for temperature determinations. As well as the homogenization of magmatic inclusions in ultramafic rocks, processes such as whisker crystal formation or transcrystalline migration of inclusions can be investigated using the new stage thanks to its very high maximum temperature and to the thermal gradients observed close to the heating wires. This new device looks to be a very promising tool that could easily be adapted for a range of studies by changing the nature and shape of the heating filaments. |
Tissandier, L., Rollion-Bard, C. Influence of glass composition on secondary ion mass spectrometry instrumental mass fractionation for Si and Ca isotopic analyses (Article de journal) Dans: Rapid Communications in Mass Spectrometry, vol. 31, p. 351–361, 2017. @article{Tissandier+Rollion-Bard2017,
title = {Influence of glass composition on secondary ion mass spectrometry instrumental mass fractionation for Si and Ca isotopic analyses},
author = {L. Tissandier and C. Rollion-Bard},
doi = {10.1002/rcm.7799},
year = {2017},
date = {2017-01-01},
journal = {Rapid Communications in Mass Spectrometry},
volume = {31},
pages = {351--361},
abstract = {RATIONALE: In situ secondary ion mass spectrometry (SIMS) analysis requires the use of standards to unravel the instrumental mass fractionation (IMF) induced by the analytical procedures. Part of this IMF might be caused by the natureof the sample and the differences in composition and structure between the sample and the standards. This textquotelefttextquoteleftmatrix effecttextquoterighttextquoteright has been tentatively corrected for by using standards with chemical compositions equivalent to the samples, or by theempirical use of chemical parameters. However, these corrections can only be applied to a narrow compositional range and fail to take proper account of the matrix effect when a wider chemical field is tested.METHODS: We synthesized a series of glasses whose compositions span a very large part of the NCMAS (Na2O-CaO-MgOAl2O3-SiO2) system. Si and Caisotopic analyses were performed on two ion microprobes (CamecaIMS-1270 and IMS-1280).RESULTS: The matrix effect observed may reach 20texttenthousand between extreme compositions and cannot be accounted for by the previously used textquotelefttextquoteleftchemicaltextquoterighttextquoteright parameters (e.g. SiO2, SiO2/(SiO2+Al2O3)) nor by the NBO/T parameter. It therefore appears necessary to consider not only the structure of the glasses, but also the nature of the different atoms. Consequently, we assessed the use of another concept, the optical basicity, based on the electronegativities of the constitutive elements of glass.CONCLUSIONS: We show that this parameter significantly improves the efficiency of the matrix-effect correction and that it can be applied across the entire NCMAS compositional range studied here. Furthermore, the use of optical basicityreduces the number of glass standards required for a reliable isotopic study, and it can also be used to probe the structure of the glass.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
RATIONALE: In situ secondary ion mass spectrometry (SIMS) analysis requires the use of standards to unravel the instrumental mass fractionation (IMF) induced by the analytical procedures. Part of this IMF might be caused by the natureof the sample and the differences in composition and structure between the sample and the standards. This textquotelefttextquoteleftmatrix effecttextquoterighttextquoteright has been tentatively corrected for by using standards with chemical compositions equivalent to the samples, or by theempirical use of chemical parameters. However, these corrections can only be applied to a narrow compositional range and fail to take proper account of the matrix effect when a wider chemical field is tested.METHODS: We synthesized a series of glasses whose compositions span a very large part of the NCMAS (Na2O-CaO-MgOAl2O3-SiO2) system. Si and Caisotopic analyses were performed on two ion microprobes (CamecaIMS-1270 and IMS-1280).RESULTS: The matrix effect observed may reach 20texttenthousand between extreme compositions and cannot be accounted for by the previously used textquotelefttextquoteleftchemicaltextquoterighttextquoteright parameters (e.g. SiO2, SiO2/(SiO2+Al2O3)) nor by the NBO/T parameter. It therefore appears necessary to consider not only the structure of the glasses, but also the nature of the different atoms. Consequently, we assessed the use of another concept, the optical basicity, based on the electronegativities of the constitutive elements of glass.CONCLUSIONS: We show that this parameter significantly improves the efficiency of the matrix-effect correction and that it can be applied across the entire NCMAS compositional range studied here. Furthermore, the use of optical basicityreduces the number of glass standards required for a reliable isotopic study, and it can also be used to probe the structure of the glass. |
2016
|
Amalberti, J., Burnard, P., Laporte, D., Tissandier, L., Neuville, D. R. Multidiffusion mechanisms for noble gases (He, Ne, Ar) in silicate glasses and melts in the transition temperature domain: Implications for glass polymerization (Article de journal) Dans: Geochimica et Cosmochimica Acta, vol. 172, p. 107–126, 2016. @article{Amalberti_etal2016,
title = {Multidiffusion mechanisms for noble gases (He, Ne, Ar) in silicate glasses and melts in the transition temperature domain: Implications for glass polymerization},
author = {J. Amalberti and P. Burnard and D. Laporte and L. Tissandier and D. R. Neuville},
doi = {10.1016/j.gca.2015.09.027},
year = {2016},
date = {2016-01-01},
journal = {Geochimica et Cosmochimica Acta},
volume = {172},
pages = {107--126},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Piani, L., Marrocchi, Y., Libourel, G., Tissandier, L. Magmatic sulfides in the porphyritic chondrules of EH enstatite chondrites (Article de journal) Dans: Geochimica et Cosmochimica Acta, vol. 195, p. 84–99, 2016. @article{Piani_etal2016,
title = {Magmatic sulfides in the porphyritic chondrules of EH enstatite chondrites},
author = {L. Piani and Y. Marrocchi and G. Libourel and L. Tissandier},
doi = {10.1016/j.gca.2016.09.010},
year = {2016},
date = {2016-01-01},
journal = {Geochimica et Cosmochimica Acta},
volume = {195},
pages = {84--99},
abstract = {The nature and distribution of sulfides within 17 porphyritic chondrules of the Sahara 97096 EH3 enstatite chondrite have been studied by backscattered electron microscopy and electron microprobe in order to investigate the role of gas--melt interactions in the chondrule sulfide formation. Troilite (FeS) is systematically present and is the most abundant sulfide within the EH3 chondrite chondrules. It is found either poikilitically enclosed in low-Ca pyroxenes or scattered within the glassy mesostasis. Oldhamite (CaS) and niningerite [(Mg,Fe,Mn)S] are present in ≈60% of the chondrules studied. While oldhamite is preferentially present in the mesostasis, niningerite associated with silica is generally observed in contact with troilite and low-Ca pyroxene. The Sahara 97096 chondrulemesostases contain high abundances of alkali and volatile elements (average Na2O = 8.7 wt.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The nature and distribution of sulfides within 17 porphyritic chondrules of the Sahara 97096 EH3 enstatite chondrite have been studied by backscattered electron microscopy and electron microprobe in order to investigate the role of gas--melt interactions in the chondrule sulfide formation. Troilite (FeS) is systematically present and is the most abundant sulfide within the EH3 chondrite chondrules. It is found either poikilitically enclosed in low-Ca pyroxenes or scattered within the glassy mesostasis. Oldhamite (CaS) and niningerite [(Mg,Fe,Mn)S] are present in ≈60% of the chondrules studied. While oldhamite is preferentially present in the mesostasis, niningerite associated with silica is generally observed in contact with troilite and low-Ca pyroxene. The Sahara 97096 chondrulemesostases contain high abundances of alkali and volatile elements (average Na2O = 8.7 wt. |
Soulié, C., Libourel, G., Tissandier, L. Olivine dissolution in molten silicates: An experimental study with application to chondrule formation (Article de journal) Dans: Meteoritics & Planetary Science, p. 1–26, 2016. @article{Souli_etal2016,
title = {Olivine dissolution in molten silicates: An experimental study with application to chondrule formation},
author = {C. Souli\'{e} and G. Libourel and L. Tissandier},
doi = {10.1111/maps.12792},
year = {2016},
date = {2016-01-01},
journal = {Meteoritics \& Planetary Science},
pages = {1--26},
abstract = {A--Mg-rich olivine is a ubiquitous phase in type I porphyritic chondrules in variousclasses of chondritic meteorites. The anhedral shape of olivine grains, their sizedistribution, as well as their poikilitic textures within low-Ca pyroxene suggest that olivines suffer dissolution during chondrule formation. Owing to a set of high-temperature experiments (1450--1540 textdegreeC) we determined the kinetics of resorption of forsterite in molten silicates, using for the first time X-ray microtomography. Results indicate that forsterite dissolution in chondrule-like melts is a very fast process with rates that range from textasciitilde5 lm min -1 to textasciitilde22 lm min-1. Forsterite dissolution strongly depends on the melt composition, with rates decreasing with increasing the magnesium and/or the silica content of the melt. An empirical model based on forsterite saturation and viscosity of the startingmelt composition successfully reproduces the forsteritic olivine dissolution rates as a function of temperature and composition for both our experiments and those of the literature. Application of our results to chondrules could explain the textures of zoned type I chondrules during their formation by gas-melt interaction. We show that the olivine/liquid ratio on one hand and the silica entrance from the gas phase (SiOg) into the chondrule melt on the other hand, have counteracting effects on the Mg-rich olivine dissolution behavior. Silica entrance would favor dissolution by maintaining disequilibrium between olivine and melt. Hence, this would explain the preferential dissolution of olivine as well as the preferential abundances of pyroxene at the margins of chondrules. Incipientdissolution would also occur in the silica-poorer melt of chondrule core but should be followed by crystallization of new olivine (overgrowth and/or newly grown crystals). While explaining textures and grain size distributions of olivines, as well as the centripetal distribution of low-Ca pyroxene in porphyritic chondrules, this scenario could also be consistent with the diverse chemical, isotopic, and thermal conditions recorded by olivines in a given chondrule.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A--Mg-rich olivine is a ubiquitous phase in type I porphyritic chondrules in variousclasses of chondritic meteorites. The anhedral shape of olivine grains, their sizedistribution, as well as their poikilitic textures within low-Ca pyroxene suggest that olivines suffer dissolution during chondrule formation. Owing to a set of high-temperature experiments (1450--1540 textdegreeC) we determined the kinetics of resorption of forsterite in molten silicates, using for the first time X-ray microtomography. Results indicate that forsterite dissolution in chondrule-like melts is a very fast process with rates that range from textasciitilde5 lm min -1 to textasciitilde22 lm min-1. Forsterite dissolution strongly depends on the melt composition, with rates decreasing with increasing the magnesium and/or the silica content of the melt. An empirical model based on forsterite saturation and viscosity of the startingmelt composition successfully reproduces the forsteritic olivine dissolution rates as a function of temperature and composition for both our experiments and those of the literature. Application of our results to chondrules could explain the textures of zoned type I chondrules during their formation by gas-melt interaction. We show that the olivine/liquid ratio on one hand and the silica entrance from the gas phase (SiOg) into the chondrule melt on the other hand, have counteracting effects on the Mg-rich olivine dissolution behavior. Silica entrance would favor dissolution by maintaining disequilibrium between olivine and melt. Hence, this would explain the preferential dissolution of olivine as well as the preferential abundances of pyroxene at the margins of chondrules. Incipientdissolution would also occur in the silica-poorer melt of chondrule core but should be followed by crystallization of new olivine (overgrowth and/or newly grown crystals). While explaining textures and grain size distributions of olivines, as well as the centripetal distribution of low-Ca pyroxene in porphyritic chondrules, this scenario could also be consistent with the diverse chemical, isotopic, and thermal conditions recorded by olivines in a given chondrule. |
2014
|
Dauphas, N., Roskosz, M., Alp, E. E., Neuville, D. R., Hu, M. Y., Sio, C. K., Tissot, F. L. H., Zhao, J., Tissandier, L., Médard, E., Cordier, C. Magma redox and structural controls on iron isotope variations in Earthtextquoterights mantle and crust (Article de journal) Dans: Earth and Planetary Science Letters, vol. 398, p. 127–140, 2014. @article{Dauphas_etal2014,
title = {Magma redox and structural controls on iron isotope variations in Earthtextquoterights mantle and crust},
author = {N. Dauphas and M. Roskosz and E. E. Alp and D. R. Neuville and M. Y. Hu and C. K. Sio and F. L. H. Tissot and J. Zhao and L. Tissandier and E. M\'{e}dard and C. Cordier},
doi = {10.1016/j.epsl.2014.04.033},
year = {2014},
date = {2014-01-01},
journal = {Earth and Planetary Science Letters},
volume = {398},
pages = {127--140},
abstract = {The heavy iron isotopic composition of Earthtextquoterights crust relative to chondrites has been explained by vaporization during the Moon-forming impact, equilibrium partitioning between metal and silicate at core--mantle-boundary conditions, or partial melting and magma differentiation. The latter view is supported by the observed difference in the iron isotopic compositions of MORBS and peridotites. However, the precise controls on iron isotope variations in igneous rocks remain unknown. Here, we show that equilibrium iron isotope fractionation is mainly controlled by redox (Fe3+/Fe tot ratio) and structural (e.g., polymerization) conditions in magmas. We measured, for the first time, the mean force of iron bonds in silicate glasses by synchrotron Nuclear Resonant Inelastic X-ray Scattering (NRIXS, also known as Nuclear Resonance Vibrational Spectroscopy -- NRVS, or Nuclear Inelastic Scattering -- NIS). The same samples were studied by conventional M\"{o}ssbauer and X-ray Absorption Near Edge Structure (XANES) spectroscopy. The NRIXS results reveal a+0.2to+0.4 equilibrium fractionation on 56Fe/54Fe ratio between Fe 2+ and Fe3+ end-members in basalt, andesite, and dacite glasses at magmatic temperatures. These first measurements can already explain�`u1/3 of the iron isotopic shift measured in MORBs relative to their source. Further work will be required to investigate how pressure, temperature, and structural differences between melts and glasses affect equilibrium fractionation factors. In addition, large fractionation is also found between rhyolitic glass and commonly occurring oxide and silicate minerals. This fractionation reflects mainly changes in the coordination environment of Fe2+in rhyolites relative to less silicic magmas and mantle minerals, as also seen by XANES. We provide a new calibration of XANES features vs. Fe3+/Fetot ratio determinations by M\"{o}ssbauer to estimate Fe 3+/Fe tot ratio in situ in glasses of basaltic, andesitic, dacitic, and rhyolitic compositions. Modeling of magma differentiation using rhyolite-MELTS shows that iron structural changes in silicic magmas can explain the heavy iron isotopic compositions of granitoids and rhyolites. This study demonstrates that iron stable isotopes can help reveal planetary redox conditions and igneous processes. Other heterovalent elements such as Ti, V, Eu, Cr, Ce, or U may show similar isotopic variations in bulk rocks and individual minerals, which could be used to establish past and present redox condition in the mantles of Earth and other planets.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The heavy iron isotopic composition of Earthtextquoterights crust relative to chondrites has been explained by vaporization during the Moon-forming impact, equilibrium partitioning between metal and silicate at core--mantle-boundary conditions, or partial melting and magma differentiation. The latter view is supported by the observed difference in the iron isotopic compositions of MORBS and peridotites. However, the precise controls on iron isotope variations in igneous rocks remain unknown. Here, we show that equilibrium iron isotope fractionation is mainly controlled by redox (Fe3+/Fe tot ratio) and structural (e.g., polymerization) conditions in magmas. We measured, for the first time, the mean force of iron bonds in silicate glasses by synchrotron Nuclear Resonant Inelastic X-ray Scattering (NRIXS, also known as Nuclear Resonance Vibrational Spectroscopy -- NRVS, or Nuclear Inelastic Scattering -- NIS). The same samples were studied by conventional Mössbauer and X-ray Absorption Near Edge Structure (XANES) spectroscopy. The NRIXS results reveal a+0.2to+0.4 equilibrium fractionation on 56Fe/54Fe ratio between Fe 2+ and Fe3+ end-members in basalt, andesite, and dacite glasses at magmatic temperatures. These first measurements can already explain�`u1/3 of the iron isotopic shift measured in MORBs relative to their source. Further work will be required to investigate how pressure, temperature, and structural differences between melts and glasses affect equilibrium fractionation factors. In addition, large fractionation is also found between rhyolitic glass and commonly occurring oxide and silicate minerals. This fractionation reflects mainly changes in the coordination environment of Fe2+in rhyolites relative to less silicic magmas and mantle minerals, as also seen by XANES. We provide a new calibration of XANES features vs. Fe3+/Fetot ratio determinations by Mössbauer to estimate Fe 3+/Fe tot ratio in situ in glasses of basaltic, andesitic, dacitic, and rhyolitic compositions. Modeling of magma differentiation using rhyolite-MELTS shows that iron structural changes in silicic magmas can explain the heavy iron isotopic compositions of granitoids and rhyolites. This study demonstrates that iron stable isotopes can help reveal planetary redox conditions and igneous processes. Other heterovalent elements such as Ti, V, Eu, Cr, Ce, or U may show similar isotopic variations in bulk rocks and individual minerals, which could be used to establish past and present redox condition in the mantles of Earth and other planets. |
Faure, F., Tissandier, L. Contrasted liquid lines of descent revealed by olivine-hosted melt inclusions and the external magma (Article de journal) Dans: Journal of Petrology, vol. 55, no. 9, p. 1779–1798, 2014. @article{Faure+Tissandier2014,
title = {Contrasted liquid lines of descent revealed by olivine-hosted melt inclusions and the external magma},
author = {F. Faure and L. Tissandier},
doi = {To better understand the significance of the chemical compositions of forsterite-hosted melt inclusi},
year = {2014},
date = {2014-01-01},
journal = {Journal of Petrology},
volume = {55},
number = {9},
pages = {1779--1798},
abstract = {To better understand the significance of the chemical compositions of forsterite-hosted melt inclusions, dynamic crystallization experiments were performed at atmospheric pressure and a low cooling rate (28Ch1) on a starting glass material with a composition in the CMAS system (12textperiodcentered21wt % CaO, 28textperiodcentered48 wt % MgO, 11textperiodcentered96 wt % Al2O3,47textperiodcentered32 wt % SiO2). Experiments were quenched at various temperatures, both above and below the theoretical solidus. Olivine is the liquidus phase and the mesostasis may exhibit a second crystalline phase corresponding to a metastable Al-rich pyroxene. Olivine crystal morphologies change from polyhedral to skeletal, depending on the quenching temperature. Regardless of the quenching temperature, the chemical compositions of liquids trapped in melt (now glass) inclusionsin the olivines do not contain the boundary layer that should result from rapid growth of these crystals. The liquid compositions also show that down to temperatures far below the theoretical solidus, olivine is the only phase that crystallizes on the walls of these inclusions. Glass inclusion analyses can therefore be used to determine the chemical evolution of a liquid in metastable equilibrium with the host olivine, irrespective of the quenching temperature. Melt inclusions therefore follow their own liquid line of descent distinct from that of the whole charge. This experimental study suggests that it should be possible to (1) draw the metastable extensions of the liquidus from natural glass inclusions and (2) determine the real supersaturation degrees of the residual magmas.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
To better understand the significance of the chemical compositions of forsterite-hosted melt inclusions, dynamic crystallization experiments were performed at atmospheric pressure and a low cooling rate (28Ch1) on a starting glass material with a composition in the CMAS system (12textperiodcentered21wt % CaO, 28textperiodcentered48 wt % MgO, 11textperiodcentered96 wt % Al2O3,47textperiodcentered32 wt % SiO2). Experiments were quenched at various temperatures, both above and below the theoretical solidus. Olivine is the liquidus phase and the mesostasis may exhibit a second crystalline phase corresponding to a metastable Al-rich pyroxene. Olivine crystal morphologies change from polyhedral to skeletal, depending on the quenching temperature. Regardless of the quenching temperature, the chemical compositions of liquids trapped in melt (now glass) inclusionsin the olivines do not contain the boundary layer that should result from rapid growth of these crystals. The liquid compositions also show that down to temperatures far below the theoretical solidus, olivine is the only phase that crystallizes on the walls of these inclusions. Glass inclusion analyses can therefore be used to determine the chemical evolution of a liquid in metastable equilibrium with the host olivine, irrespective of the quenching temperature. Melt inclusions therefore follow their own liquid line of descent distinct from that of the whole charge. This experimental study suggests that it should be possible to (1) draw the metastable extensions of the liquidus from natural glass inclusions and (2) determine the real supersaturation degrees of the residual magmas. |
Kuga, M., Carrasco, N., Marty, B., Marrocchi, Y., Bernard, S., Rigaudier, T., Fleury, B., Tissandier, L. Nitrogen isotopic fractionation during abiotic synthesis of organic solid particles (Article de journal) Dans: Earth and Planetary Science Letters, vol. 393, p. 2–13, 2014. @article{Kuga_etal2014,
title = {Nitrogen isotopic fractionation during abiotic synthesis of organic solid particles},
author = {M. Kuga and N. Carrasco and B. Marty and Y. Marrocchi and S. Bernard and T. Rigaudier and B. Fleury and L. Tissandier},
doi = {10.1016/j.epsl.2014.02.037},
year = {2014},
date = {2014-01-01},
journal = {Earth and Planetary Science Letters},
volume = {393},
pages = {2--13},
abstract = {The formation of organic compounds is generally assumed to result from abiotic processes in the Solar System, with the exception of biogenic organics on Earth. Nitrogen-bearing organics are of particular interest, notably for prebiotic perspectives but also for over all comprehension of organic formation in the young Solar System and in planetary atmospheres. We have investigated abiotic synthesis of organics upon plasma discharge, with special attention to N isotope fractionation. Organic aerosols were synthesized from N2--CH4 and N2--CO gaseous mixtures using low-pressure plasma discharge experiments, aimed at simulating chemistry occurring in Titantextquoteright atmosphere and in the protosolar nebula, respectively. The nitrogen content, the N speciation and the N isotopic composition were analyzed in the resulting organic aerosols. Nitrogen is efficiently incorporated in to the synthesized solids, independently of the oxidation degree, of the N2 content of the starting gas mixture, and of the nitrogen speciation in the aerosols.The aerosols are depleted in 15N by15--25- relative to the initial N2 gas, whatever the experimental setup is. Such an isotopic fractionation is attributed to mass-dependent kinetic effect(s). Nitrogen isotope fractionation upon electric discharge cannot account for the large N isotope variations observed among Solar System objects and reservoirs. Extreme N isotope signatures in the Solar System are more likely the result of self-shielding during N2 photodissociation, exotic effect during photodissociation of N2 and/or low temperature ion-molecule isotope exchange. Kinetic N isotope fractionation may play a significant role in the Titantextquoterights atmosphere. On the Titantextquoterights night side, 15N depletion resulting from electron driven reactions may counterbalance photo-induced 15N enrichments occurring on the daytextquoterights side.We also suggest that the low $delta$15N values of Archaean organic matter (Beaumont and Robert,1999) are partly the result of abiotic synthesis of organics that occurred at that time, and that the subsequent development of the biosphere resulted in shifts of $delta$15N towards higher values.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The formation of organic compounds is generally assumed to result from abiotic processes in the Solar System, with the exception of biogenic organics on Earth. Nitrogen-bearing organics are of particular interest, notably for prebiotic perspectives but also for over all comprehension of organic formation in the young Solar System and in planetary atmospheres. We have investigated abiotic synthesis of organics upon plasma discharge, with special attention to N isotope fractionation. Organic aerosols were synthesized from N2--CH4 and N2--CO gaseous mixtures using low-pressure plasma discharge experiments, aimed at simulating chemistry occurring in Titantextquoteright atmosphere and in the protosolar nebula, respectively. The nitrogen content, the N speciation and the N isotopic composition were analyzed in the resulting organic aerosols. Nitrogen is efficiently incorporated in to the synthesized solids, independently of the oxidation degree, of the N2 content of the starting gas mixture, and of the nitrogen speciation in the aerosols.The aerosols are depleted in 15N by15--25- relative to the initial N2 gas, whatever the experimental setup is. Such an isotopic fractionation is attributed to mass-dependent kinetic effect(s). Nitrogen isotope fractionation upon electric discharge cannot account for the large N isotope variations observed among Solar System objects and reservoirs. Extreme N isotope signatures in the Solar System are more likely the result of self-shielding during N2 photodissociation, exotic effect during photodissociation of N2 and/or low temperature ion-molecule isotope exchange. Kinetic N isotope fractionation may play a significant role in the Titantextquoterights atmosphere. On the Titantextquoterights night side, 15N depletion resulting from electron driven reactions may counterbalance photo-induced 15N enrichments occurring on the daytextquoterights side.We also suggest that the low $delta$15N values of Archaean organic matter (Beaumont and Robert,1999) are partly the result of abiotic synthesis of organics that occurred at that time, and that the subsequent development of the biosphere resulted in shifts of $delta$15N towards higher values. |
2013
|
Devineau, K., Devouard, B., Leroux, H., Tissandier, L. Incorporation of Zn in the destabilization products of muscovite at 1175 textdegreeC under disequilibrium conditions, and implications for heavy metal sequestration (Article de journal) Dans: American Mineralogist, vol. 98, p. 932–945, 2013. @article{Devineau_etal2013,
title = {Incorporation of Zn in the destabilization products of muscovite at 1175 textdegreeC under disequilibrium conditions, and implications for heavy metal sequestration},
author = {K. Devineau and B. Devouard and H. Leroux and L. Tissandier},
doi = {doi.org/10.2138/am.2013.4213},
year = {2013},
date = {2013-01-01},
journal = {American Mineralogist},
volume = {98},
pages = {932--945},
abstract = {This work reports on the thermal decomposition of muscovite within a granite powder doped with 8.5 wt% ZnO and heated during 10 min to 68 h at 1175 textdegreeC, and the implications for the sequestration of Zn, and other heavy metalts in such decomposition products. Samples were characterized using analytical scanning and transmission electron microscopy. After 10 min, muscovite is completely pseudomorphosed by Si-rich glass, spinel structure phases, and minor mullite. Spinel phases incorporate Zn, but their compositions depend on their position within the muscovite pseudomorphs. Al-rich oxides crystallize at the core of the pseudomorphs while Zn-Al spinels are located at the rims. The most Al-rich spinels have compositions close to $gamma$-Al2O3, a metastable transition alumina, with up to 5 wt% MgO, 2 wt% Fe2O3, 4 wt% ZnO, and 9 wt% SiO2. The most Zn-rich spinels show compositions intermediate between Al2O3 and gahnite (ZnAl2O4), with up to 31 wt% ZnO and significant contents of MgO (3 wt%), Fe2O3 (5 wt%), and SiO2 (10 wt%). After 68 h, stable spinels are gahnite close to the end-member composition with MgO and Fe2O3 contents below ca. 5 wt%, and SiO2 contents ca. 1 wt%. These results support the existence of a metastable solid solution between $gamma$-Al2O3 and gahnite. This experimental work shows that Zn can be incorporated in spinel structures after heating at 1175 textdegreeC during short durations and Zn is preferentially incorporated in the muscovite pseudomorphs as opposed to the Qtz-Fds glass. Consequently, the thermal breakdown of phyllosilicates can be a viable process to immobilize heavy metals such as Zn.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This work reports on the thermal decomposition of muscovite within a granite powder doped with 8.5 wt% ZnO and heated during 10 min to 68 h at 1175 textdegreeC, and the implications for the sequestration of Zn, and other heavy metalts in such decomposition products. Samples were characterized using analytical scanning and transmission electron microscopy. After 10 min, muscovite is completely pseudomorphosed by Si-rich glass, spinel structure phases, and minor mullite. Spinel phases incorporate Zn, but their compositions depend on their position within the muscovite pseudomorphs. Al-rich oxides crystallize at the core of the pseudomorphs while Zn-Al spinels are located at the rims. The most Al-rich spinels have compositions close to $gamma$-Al2O3, a metastable transition alumina, with up to 5 wt% MgO, 2 wt% Fe2O3, 4 wt% ZnO, and 9 wt% SiO2. The most Zn-rich spinels show compositions intermediate between Al2O3 and gahnite (ZnAl2O4), with up to 31 wt% ZnO and significant contents of MgO (3 wt%), Fe2O3 (5 wt%), and SiO2 (10 wt%). After 68 h, stable spinels are gahnite close to the end-member composition with MgO and Fe2O3 contents below ca. 5 wt%, and SiO2 contents ca. 1 wt%. These results support the existence of a metastable solid solution between $gamma$-Al2O3 and gahnite. This experimental work shows that Zn can be incorporated in spinel structures after heating at 1175 textdegreeC during short durations and Zn is preferentially incorporated in the muscovite pseudomorphs as opposed to the Qtz-Fds glass. Consequently, the thermal breakdown of phyllosilicates can be a viable process to immobilize heavy metals such as Zn. |
2012
|
Faure, F., Tissandier, L., Libourel, G., Mathieu, R., Welsch, B. Origin of glass inclusions hosted in magnesian porphyritic olivines chondrules: Deciphering planetesimal compositions (Article de journal) Dans: Earth and Planetary Science Letters, vol. 319-320, p. 1–8, 2012. @article{Faure_etal2012,
title = {Origin of glass inclusions hosted in magnesian porphyritic olivines chondrules: Deciphering planetesimal compositions},
author = {F. Faure and L. Tissandier and G. Libourel and R. Mathieu and B. Welsch},
doi = {10.1016/j.epsl.2011.12.013},
year = {2012},
date = {2012-01-01},
journal = {Earth and Planetary Science Letters},
volume = {319-320},
pages = {1--8},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2011
|
Mathieu, R., Libourel, G., Deloule, E., Tissandier, L., Rapin, C., Podor, R. Na2O solubility in CaO-MgO-SiO2 melts (Article de journal) Dans: Geochimica et Cosmochimica Acta, vol. 75, no. 2, p. 608–628, 2011. @article{Mathieu_etal2011,
title = {Na2O solubility in CaO-MgO-SiO2 melts},
author = {R. Mathieu and G. Libourel and E. Deloule and L. Tissandier and C. Rapin and R. Podor},
doi = {10.1016/j.gca.2010.11.001},
year = {2011},
date = {2011-01-01},
journal = {Geochimica et Cosmochimica Acta},
volume = {75},
number = {2},
pages = {608--628},
abstract = {AbstractThe sodium solubility in silicate melts in the CaO--MgO--SiO2 (CMS) system at 1400 C has been measured by using a closed thermochemical reactor designed to control alkali metal activity. In this reactor, Na(g) evaporation from a Na2O--xSiO2melt imposes an alkali metal vapor pressure in equilibrium with the molten silicate samples. Because of equilibrium conditions in the reactor, the activity of sodium-metal oxide in the molten samples is the same as that of the source, i.e., aNa2O(sample) = aNa2O(source). This design also allows to determine the sodium oxide activity coefficient in the samples. Thirty-three different CMS compositions were studied. The results show that the amount of sodium entering from the gas phase (i.e., Na2O solubility) is strongly sensitive to silica content of the melt and, to a lesser extent, the relative amounts of CaO and MgO. Despitethe large range of tested melt compositions (0 \< CaO and MgO \< 40; 40 \< SiO2 \< 100; in wt%), we found that Na2O solubility is conveniently modeled as a linear function of the optical basicity (K) calculated on a Na-free basis melt composition. In our experiments, cNa2O(sample) ranges from 7 10 7 to 5 10 6, indicating a strongly non-ideal behavior of Na2O solubility in the studied CMS melts (cNa2O(sample) 1). In addition to showing the effect of sodium on phase relationships in the CMS system, this Na2O solubility study brings valuable new constraints on how melt structure controls the solubility of Na in theCMS silicate melts. Our results suggest that Na2O addition causes depolymerization of the melt by preferential breaking of Si--O--Si bonds of the most polymerized tetrahedral sites, mainly Q4.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
AbstractThe sodium solubility in silicate melts in the CaO--MgO--SiO2 (CMS) system at 1400 C has been measured by using a closed thermochemical reactor designed to control alkali metal activity. In this reactor, Na(g) evaporation from a Na2O--xSiO2melt imposes an alkali metal vapor pressure in equilibrium with the molten silicate samples. Because of equilibrium conditions in the reactor, the activity of sodium-metal oxide in the molten samples is the same as that of the source, i.e., aNa2O(sample) = aNa2O(source). This design also allows to determine the sodium oxide activity coefficient in the samples. Thirty-three different CMS compositions were studied. The results show that the amount of sodium entering from the gas phase (i.e., Na2O solubility) is strongly sensitive to silica content of the melt and, to a lesser extent, the relative amounts of CaO and MgO. Despitethe large range of tested melt compositions (0 < CaO and MgO < 40; 40 < SiO2 < 100; in wt%), we found that Na2O solubility is conveniently modeled as a linear function of the optical basicity (K) calculated on a Na-free basis melt composition. In our experiments, cNa2O(sample) ranges from 7 10 7 to 5 10 6, indicating a strongly non-ideal behavior of Na2O solubility in the studied CMS melts (cNa2O(sample) 1). In addition to showing the effect of sodium on phase relationships in the CMS system, this Na2O solubility study brings valuable new constraints on how melt structure controls the solubility of Na in theCMS silicate melts. Our results suggest that Na2O addition causes depolymerization of the melt by preferential breaking of Si--O--Si bonds of the most polymerized tetrahedral sites, mainly Q4. |
2008
|
Mathieu, R., Khedim, H., Libourel, G., Podor, R., Tissandier, L., Deloule, E., Faure, F., Rapin, C., Vilasi, M. Control of alkali-metal oxide activity in molten silicates (Article de journal) Dans: Journal of Non-Crystalline Solids, vol. 254, no. 45-46, p. 5079–5083, 2008. @article{Mathieu_etal2008,
title = {Control of alkali-metal oxide activity in molten silicates},
author = {R. Mathieu and H. Khedim and G. Libourel and R. Podor and L. Tissandier and E. Deloule and F. Faure and C. Rapin and M. Vilasi},
doi = {10.1016/j.jnoncrysol.2008.07.004},
year = {2008},
date = {2008-01-01},
journal = {Journal of Non-Crystalline Solids},
volume = {254},
number = {45-46},
pages = {5079--5083},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2007
|
Krot, A. N., Yurimoto, H., Hutcheon, I. D., Libourel, G., Chaussidon, M., Tissandier, L., al., Type C Ca, Al-rich inclusions from Allende: Evidence for multistage formation (Article de journal) Dans: Geochimica et Cosmochimica Acta, vol. 71, p. 4342–4364, 2007. @article{Krot_etal2007_2,
title = {Type C Ca, Al-rich inclusions from Allende: Evidence for multistage formation},
author = {A. N. Krot and H. Yurimoto and I. D. Hutcheon and G. Libourel and M. Chaussidon and L. Tissandier and al.},
doi = {10.1016/j.gca.2007.03.040},
year = {2007},
date = {2007-01-01},
journal = {Geochimica et Cosmochimica Acta},
volume = {71},
pages = {4342--4364},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2006
|
Libourel, G., Krot, A. N., Tissandier, L. Role of gas-melt interaction during chondrule formation (Article de journal) Dans: Earth and Planetary Science Letters, vol. 251, no. 3-4, p. 232–240, 2006. @article{Libourel_etal2006,
title = {Role of gas-melt interaction during chondrule formation},
author = {G. Libourel and A. N. Krot and L. Tissandier},
doi = {10.1016/j.epsl.2006.09.011},
year = {2006},
date = {2006-01-01},
journal = {Earth and Planetary Science Letters},
volume = {251},
number = {3-4},
pages = {232--240},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2002
|
Tissandier, L., Libourel, G., Robert, F. Gas-melt interactions and their bearing on chondrule formation (Article de journal) Dans: Meteoritics & Planetary Science, vol. 37, no. 10, p. 1377–1389, 2002. @article{Tissandier_etal2002,
title = {Gas-melt interactions and their bearing on chondrule formation},
author = {L. Tissandier and G. Libourel and F. Robert},
year = {2002},
date = {2002-01-01},
journal = {Meteoritics \& Planetary Science},
volume = {37},
number = {10},
pages = {1377--1389},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
