2023
|
Piralla, M., Villeneuve, J., Schnuriger, N., Bekaert, D. V., Marrocchi, Y. A unified chronology of dust formation in the early solar system (Article de journal) Dans: Icarus, vol. 394, p. 115427, 2023. @article{Piralla_etal2023,
title = {A unified chronology of dust formation in the early solar system},
author = {M. Piralla and J. Villeneuve and N. Schnuriger and D. V. Bekaert and Y. Marrocchi},
doi = {10.1016/j.icarus.2023.115427},
year = {2023},
date = {2023-01-01},
urldate = {2023-01-01},
journal = {Icarus},
volume = {394},
pages = {115427},
abstract = {The chronology of dust formation in the early solar system remains controversial. Chondrules are the most abundant high-temperature objects formed during the evolution of the circumsolar disk. Considering chondrule formation, absolute lead‑lead (Pb--Pb) ages and aluminum‑magnesium (26Al--26Mg) ages relative to calcium‑aluminum-rich inclusions (CAIs) provide inconsistent chronologies, with Pb--Pb ages showing early and protracted chondrule formation episodes whereas 26Al--26Mg ages suggest that chondrule production was delayed by \>1.5 Ma. Here, we develop a new method to precisely determine in situ 26Al--26Mg ages of spinelbearing chondrules, which are not affected by secondary asteroidal processes. Our data demonstrate that 26Al--26Mg chondrule formation ages are actually 1 Ma older than previously thought and extend over the entire lifetime of the disk. This shift in chondrule formation ages relative to CAIs, however, is not sufficient to reconcilethe Pb--Pb and 26Al--26Mg chronologies of chondrule and achondrite formation. Thus, either chondrules’Pb--Pb ages and volcanic achondrites’ 26Al--26Mg ages are incorrect or the age of CAIs should be reevaluated at 4,568.7 Ma to ensure consistency between chronometers. We favor the second hypothesis, given that (i) thecanonical age of CAIs was determined using only 4 specimens and (ii) older ages of 4,568.2 Ma have also been measured. We show that the adoption of 4,568.7 Ma as the new canonical age of CAIs and the use of our new spinel-derived 26Al--26Mg ages enable reconciling the Pb--Pb and 26Al--26Mg ages of chondrules and achondrites.This new chronology implies the existence of a 0.7--1 Ma gap between the formation of refractory inclusions and chondrules, and supports the homogeneous distribution of 26Al in the circumsolar disk.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The chronology of dust formation in the early solar system remains controversial. Chondrules are the most abundant high-temperature objects formed during the evolution of the circumsolar disk. Considering chondrule formation, absolute lead‑lead (Pb--Pb) ages and aluminum‑magnesium (26Al--26Mg) ages relative to calcium‑aluminum-rich inclusions (CAIs) provide inconsistent chronologies, with Pb--Pb ages showing early and protracted chondrule formation episodes whereas 26Al--26Mg ages suggest that chondrule production was delayed by >1.5 Ma. Here, we develop a new method to precisely determine in situ 26Al--26Mg ages of spinelbearing chondrules, which are not affected by secondary asteroidal processes. Our data demonstrate that 26Al--26Mg chondrule formation ages are actually 1 Ma older than previously thought and extend over the entire lifetime of the disk. This shift in chondrule formation ages relative to CAIs, however, is not sufficient to reconcilethe Pb--Pb and 26Al--26Mg chronologies of chondrule and achondrite formation. Thus, either chondrules’Pb--Pb ages and volcanic achondrites’ 26Al--26Mg ages are incorrect or the age of CAIs should be reevaluated at 4,568.7 Ma to ensure consistency between chronometers. We favor the second hypothesis, given that (i) thecanonical age of CAIs was determined using only 4 specimens and (ii) older ages of 4,568.2 Ma have also been measured. We show that the adoption of 4,568.7 Ma as the new canonical age of CAIs and the use of our new spinel-derived 26Al--26Mg ages enable reconciling the Pb--Pb and 26Al--26Mg ages of chondrules and achondrites.This new chronology implies the existence of a 0.7--1 Ma gap between the formation of refractory inclusions and chondrules, and supports the homogeneous distribution of 26Al in the circumsolar disk. |
Marrocchi, Y., Rigaudier, T., Piralla, M., Piani, L. Hydrogen isotopic evidence for nebular pre-hydration and the limited role of parent-body processes in CM chondrites (Article de journal) Dans: Earth and Planetary Science Letters, vol. 611, no. 2, p. 118151, 2023. @article{Marrocchi_etal2023,
title = {Hydrogen isotopic evidence for nebular pre-hydration and the limited role of parent-body processes in CM chondrites},
author = {Y. Marrocchi and T. Rigaudier and M. Piralla and L. Piani},
doi = {10.1016/j.epsl.2023.118151},
year = {2023},
date = {2023-01-01},
urldate = {2023-01-01},
journal = {Earth and Planetary Science Letters},
volume = {611},
number = {2},
pages = {118151},
abstract = {The conditions and environments in which hydrated phases in unequilibrated meteorites formed remain debated. Among carbonaceous chondrites, Mighei-type chondrites (CMs) display a large range in the degree of aqueous alteration, and thus record different stages of hydration and alteration. Here, we report the bulk H, C, and N contents, H and C isotopic compositions, and thermogravimetric signatures of the most-and least-altered CMs known so far, Kolang and Asuka 12236, respectively. We also report in-situSIMS measurements of the hydrogen isotopic compositions of water in both chondrites. Compared to other CMs, Asuka 12236 has the lowest bulk water content (3.3 wt.% H2O) and the most D-rich water and bulk isotopic compositions ($delta$D =180 and 280 , respectively). Combined with literature data, our results show that phyllosilicate-bearing CMs altered to varying degrees accreted water-ice grains with similar isotopic compositions. These results demonstrate that the hydrogen isotopic variations in CM chondrites (i) are not controlled by secondary alteration processes and (ii) were mostly shaped by interactions between the protoplanetary disk and the molecular cloud that episodically fed the disk over several million years. The minimally altered CM chondrites Paris and Asuka 12236 display peculiar, D-rich, hydrogen isotopic compositions that imply the presence of another H-bearing component in addition to insoluble organic matter and phyllosilicates. This component is most likely the hydrated amorphous silicates that are ubiquitous in these chondrites. CM bulk H and O isotopic compositions are linearly correlated, implying that (i) amorphous silicates in CM matrices were already hydrated by disk processes before the onset of CM parent-body alteration, and (ii) the quest for a hypothetically water-free CM3 is illusory.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The conditions and environments in which hydrated phases in unequilibrated meteorites formed remain debated. Among carbonaceous chondrites, Mighei-type chondrites (CMs) display a large range in the degree of aqueous alteration, and thus record different stages of hydration and alteration. Here, we report the bulk H, C, and N contents, H and C isotopic compositions, and thermogravimetric signatures of the most-and least-altered CMs known so far, Kolang and Asuka 12236, respectively. We also report in-situSIMS measurements of the hydrogen isotopic compositions of water in both chondrites. Compared to other CMs, Asuka 12236 has the lowest bulk water content (3.3 wt.% H2O) and the most D-rich water and bulk isotopic compositions ($delta$D =180 and 280 , respectively). Combined with literature data, our results show that phyllosilicate-bearing CMs altered to varying degrees accreted water-ice grains with similar isotopic compositions. These results demonstrate that the hydrogen isotopic variations in CM chondrites (i) are not controlled by secondary alteration processes and (ii) were mostly shaped by interactions between the protoplanetary disk and the molecular cloud that episodically fed the disk over several million years. The minimally altered CM chondrites Paris and Asuka 12236 display peculiar, D-rich, hydrogen isotopic compositions that imply the presence of another H-bearing component in addition to insoluble organic matter and phyllosilicates. This component is most likely the hydrated amorphous silicates that are ubiquitous in these chondrites. CM bulk H and O isotopic compositions are linearly correlated, implying that (i) amorphous silicates in CM matrices were already hydrated by disk processes before the onset of CM parent-body alteration, and (ii) the quest for a hypothetically water-free CM3 is illusory. |
2022
|
Marrocchi, Y., Piralla, M., Regnault, M., Batanova, V., Villeneuve, J., Jacquet, E. Isotopic evidence for two chondrule generations in CR chondrites and their relationships to other carbonaceous chondrites (Article de journal) Dans: Earth and Planetary Science Letters, vol. 593, p. 117683, 2022. @article{Marrocchi_etal2022,
title = {Isotopic evidence for two chondrule generations in CR chondrites and their relationships to other carbonaceous chondrites},
author = {Y. Marrocchi and M. Piralla and M. Regnault and V. Batanova and J. Villeneuve and E. Jacquet},
doi = {10.1016/j.epsl.2022.117683},
year = {2022},
date = {2022-01-01},
journal = {Earth and Planetary Science Letters},
volume = {593},
pages = {117683},
abstract = {Among primitive meteorites, CR chondrites have peculiar isotopic compositions, the origin of which is uncertain and may have involved contributions from primordial molecular cloud material or the chondrites’ formation and agglomeration late during the evolution of the protoplanetary disk. Here, we report a comprehensive textural and isotopic characterization of type I CR chondrules and provide new insights on their formation conditions. We find that two chondrule populations characterized bydifferent sizes and oxygen isotopic compositions co-exist in CR chondrites. The typically larger, 16O-poor (17O \> -4) chondrules (type I-CR chondrules) appear to have formed late out of a CR reservoir already populated by typically smaller, 16O-rich (17O \< -4) chondrules (type I-CO chondrules). Before formation of type I-CR chondrules, the CR reservoir was likely dominated by CI-like dust, in line with the proximity of CR with CI chondrites for many isotopic ratios. The CR reservoir thus may have largely belonged to the continuum shown by other carbonaceous chondrites, although some isotopic ratios maintain some originality and suggest isotopic variation of CI-like dust in the outer disk. Combined with literature data,our data (i) demonstrates that recycling processes are responsible for the singular compositions of CR chondrites and their chondrules for isotopic systems with drastically different geochemical behaviors (O, Cr, Te) and (ii) support the homogeneous distribution of 26Al throughout the protoplanetary disk.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Among primitive meteorites, CR chondrites have peculiar isotopic compositions, the origin of which is uncertain and may have involved contributions from primordial molecular cloud material or the chondrites’ formation and agglomeration late during the evolution of the protoplanetary disk. Here, we report a comprehensive textural and isotopic characterization of type I CR chondrules and provide new insights on their formation conditions. We find that two chondrule populations characterized bydifferent sizes and oxygen isotopic compositions co-exist in CR chondrites. The typically larger, 16O-poor (17O > -4) chondrules (type I-CR chondrules) appear to have formed late out of a CR reservoir already populated by typically smaller, 16O-rich (17O < -4) chondrules (type I-CO chondrules). Before formation of type I-CR chondrules, the CR reservoir was likely dominated by CI-like dust, in line with the proximity of CR with CI chondrites for many isotopic ratios. The CR reservoir thus may have largely belonged to the continuum shown by other carbonaceous chondrites, although some isotopic ratios maintain some originality and suggest isotopic variation of CI-like dust in the outer disk. Combined with literature data,our data (i) demonstrates that recycling processes are responsible for the singular compositions of CR chondrites and their chondrules for isotopic systems with drastically different geochemical behaviors (O, Cr, Te) and (ii) support the homogeneous distribution of 26Al throughout the protoplanetary disk. |
Regnault, M., Marrocchi, Y., Piralla, M., Villeneuve, J., Batanova, V., Schnuriger, N., Jacquet, E. Oxygen isotope systematics of chondrules in Rumuruti chondrites : Formation conditions and genetic link with ordinary chondrites (Article de journal) Dans: Meteoritics & Planetary Science, vol. 57, no. 1, p. 122–135, 2022. @article{Regnault_etal2022,
title = {Oxygen isotope systematics of chondrules in Rumuruti chondrites : Formation conditions and genetic link with ordinary chondrites},
author = {M. Regnault and Y. Marrocchi and M. Piralla and J. Villeneuve and V. Batanova and N. Schnuriger and E. Jacquet},
doi = {10.1111/MAPS.13778},
year = {2022},
date = {2022-01-01},
journal = {Meteoritics \& Planetary Science},
volume = {57},
number = {1},
pages = {122--135},
abstract = {Rumurutiites (R chondrites) are rare, highly oxidized chondrites belonging to the noncarbonaceous superclan and characterized by low chondrule abundances. Although textural and chemical features of Rumurutiite chondrules resemble those of ordinary chondrites (OCs), their formation conditions and potential genetic link remain debated. Here, we report high-resolution elemental X-ray mapping analyses and in situ O isotopic measurements of olivine grains from five chondrules and eight isolated olivine grains (IOGs) in the NWA 12482 R3 chondrite. The chondrules show chemical zonings similar to their counterparts in ordinary and carbonaceous chondrites (CCs), implying that gas--melt interaction processes between chondrule precursors and SiO- and Mg-rich gas were operative throughout the circumsolar disk. Our isotopic data show that R chondrules are isotopically similar to ordinary chondrules, although differences in their abundances of relict olivine grains and chondrule textural characteristics suggest different formation environments, with R chondrules being formed from 16O-poorer precursors. As with chondrules in OCs, the O isotopic characteristics of R chondrules and IOGs suggest limited transport between CC and noncarbonaceous reservoirs.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Rumurutiites (R chondrites) are rare, highly oxidized chondrites belonging to the noncarbonaceous superclan and characterized by low chondrule abundances. Although textural and chemical features of Rumurutiite chondrules resemble those of ordinary chondrites (OCs), their formation conditions and potential genetic link remain debated. Here, we report high-resolution elemental X-ray mapping analyses and in situ O isotopic measurements of olivine grains from five chondrules and eight isolated olivine grains (IOGs) in the NWA 12482 R3 chondrite. The chondrules show chemical zonings similar to their counterparts in ordinary and carbonaceous chondrites (CCs), implying that gas--melt interaction processes between chondrule precursors and SiO- and Mg-rich gas were operative throughout the circumsolar disk. Our isotopic data show that R chondrules are isotopically similar to ordinary chondrules, although differences in their abundances of relict olivine grains and chondrule textural characteristics suggest different formation environments, with R chondrules being formed from 16O-poorer precursors. As with chondrules in OCs, the O isotopic characteristics of R chondrules and IOGs suggest limited transport between CC and noncarbonaceous reservoirs. |
2021
|
Jacquet, E., Piralla, M., Kersaho, P., Marrocchi, Y. Origin of isolated olivine grains in carbonaceous chondrites (Article de journal) Dans: Meteoritics & Planetary Science, vol. 56, no. 1, p. 13–33, 2021. @article{Jacquet_etal2021,
title = {Origin of isolated olivine grains in carbonaceous chondrites},
author = {E. Jacquet and M. Piralla and P. Kersaho and Y. Marrocchi},
doi = {doi: 10.1111/maps.13583},
year = {2021},
date = {2021-01-01},
journal = {Meteoritics \& Planetary Science},
volume = {56},
number = {1},
pages = {13--33},
abstract = {We report microscopic, cathodoluminescence, chemical, and O isotopic measurements of FeO-poor isolated olivine grains (IOG) in the carbonaceous chondrites Allende (CV3), Northwest Africa 5958 (C2-ung), Northwest Africa 11086 (CM2-an), and Allan Hills 77307 (CO3.0). The general petrographic, chemical, and isotopic similarity with bona fide type I chondrules confirms that the IOG derived from them. The concentric CL zoning, reflecting a decrease in refractory elements toward the margins, and frequent rimming by enstatite are taken as evidence of interaction of the IOG with the gas as standalone objects. This indicates that they were splashed out of chondrules when these were still partially molten. CaO-rich refractory forsterites, which are restricted to $Delta$17O \<-4textdegree/textdegreetextdegree likely escaped equilibration at lower temperatures because of their large size and possibly quicker quenching. The IOG thus bear witness to frequent collisions in the chondrule-forming regions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We report microscopic, cathodoluminescence, chemical, and O isotopic measurements of FeO-poor isolated olivine grains (IOG) in the carbonaceous chondrites Allende (CV3), Northwest Africa 5958 (C2-ung), Northwest Africa 11086 (CM2-an), and Allan Hills 77307 (CO3.0). The general petrographic, chemical, and isotopic similarity with bona fide type I chondrules confirms that the IOG derived from them. The concentric CL zoning, reflecting a decrease in refractory elements toward the margins, and frequent rimming by enstatite are taken as evidence of interaction of the IOG with the gas as standalone objects. This indicates that they were splashed out of chondrules when these were still partially molten. CaO-rich refractory forsterites, which are restricted to $Delta$17O <-4textdegree/textdegreetextdegree likely escaped equilibration at lower temperatures because of their large size and possibly quicker quenching. The IOG thus bear witness to frequent collisions in the chondrule-forming regions. |
Piralla, M., Tart`ese, R., Marrocchi, Y., Joy, K. H. Apatite halogen and hydrogen isotope constraints on the conditions of hydrothermal alteration in carbonaceous chondrites (Article de journal) Dans: Meteoritics & Planetary Science, vol. 56, no. 4, p. 809–828, 2021. @article{Piralla_etal2021,
title = {Apatite halogen and hydrogen isotope constraints on the conditions of hydrothermal alteration in carbonaceous chondrites},
author = {M. Piralla and R. Tart`ese and Y. Marrocchi and K. H. Joy},
doi = {10.1111/maps.13639},
year = {2021},
date = {2021-01-01},
journal = {Meteoritics \& Planetary Science},
volume = {56},
number = {4},
pages = {809--828},
abstract = {Apatite has been widely used for assessing the volatile inventory and hydrothermal fluid compositions of asteroidal and planetary bodies. We report the OH, F, and Cl abundances, as well as the hydrogen isotope composition, of apatite in the CM1-2 chondrite Boriskino and in the C1-ungrouped Bench Crater meteorite. Apatite in both meteorites is halogen-poor, close to the hydroxylapatite endmember composition, and characterized by average $delta$DSMOW values of −226 +-59% and 233 +-92%, respectively. Compared to apatite, the matrix in Bench Crater is depleted in D with a $delta$DSMOW value of −16 +-119texttenthousand. Comparing apatite and water H isotope compositions yields similar apatite-water D/H fractionation $Delta$DApatite-Water of approximately 120--150texttenthousand for both chondrites, suggesting that apatite formed at similar temperatures. Combining a lattice strain partitioning model with apatite F and Cl abundances in Boriskino and Bench Crater yields low F and Cl abundances \<300 $mu$g g−1 in apatite-forming fluids, and fluid F/Cl ratios that are roughly consistent with the bulk F/Cl ratios of other CI and CM chondrites. This suggests that hydrothermal alteration on these meteorite parent bodies took place under closed-system conditions. Based on the OH abundance estimates for the apatite-forming fluids, we estimated the pH values of alteration fluids to be of approximately 10--13. Such alkaline fluid compositions are consistent with previous modeling and suggest that apatite formed late, toward the end of completion of hydrothermal alteration processes on the Boriskino and Bench Crater parent bodies},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Apatite has been widely used for assessing the volatile inventory and hydrothermal fluid compositions of asteroidal and planetary bodies. We report the OH, F, and Cl abundances, as well as the hydrogen isotope composition, of apatite in the CM1-2 chondrite Boriskino and in the C1-ungrouped Bench Crater meteorite. Apatite in both meteorites is halogen-poor, close to the hydroxylapatite endmember composition, and characterized by average $delta$DSMOW values of −226 +-59% and 233 +-92%, respectively. Compared to apatite, the matrix in Bench Crater is depleted in D with a $delta$DSMOW value of −16 +-119texttenthousand. Comparing apatite and water H isotope compositions yields similar apatite-water D/H fractionation $Delta$DApatite-Water of approximately 120--150texttenthousand for both chondrites, suggesting that apatite formed at similar temperatures. Combining a lattice strain partitioning model with apatite F and Cl abundances in Boriskino and Bench Crater yields low F and Cl abundances <300 $mu$g g−1 in apatite-forming fluids, and fluid F/Cl ratios that are roughly consistent with the bulk F/Cl ratios of other CI and CM chondrites. This suggests that hydrothermal alteration on these meteorite parent bodies took place under closed-system conditions. Based on the OH abundance estimates for the apatite-forming fluids, we estimated the pH values of alteration fluids to be of approximately 10--13. Such alkaline fluid compositions are consistent with previous modeling and suggest that apatite formed late, toward the end of completion of hydrothermal alteration processes on the Boriskino and Bench Crater parent bodies |
Piralla, M., Villeneuve, J., Batanova, V., Jacquet, E., Marrocchi, Y. Conditions of chondrule formation in ordinary chondrites (Article de journal) Dans: Geochimica et Cosmochimica Acta, vol. 313, p. 295–312, 2021. @article{Piralla_etal2021_2,
title = {Conditions of chondrule formation in ordinary chondrites},
author = {M. Piralla and J. Villeneuve and V. Batanova and E. Jacquet and Y. Marrocchi},
doi = {10.1016/j.gca.2021.08.007},
year = {2021},
date = {2021-01-01},
journal = {Geochimica et Cosmochimica Acta},
volume = {313},
pages = {295--312},
abstract = {Chondrules are sub-millimetric spheroids that are ubiquitous in chondrites and whose formation mechanism remains elusive. Textural and oxygen isotopic characteristics of chondrules in carbonaceous chondrites (CCs) suggest that they result from the recycling of isotopically heterogeneous early-condensed precursors via gas--melt interactions. Here, we report high-resolution X-ray elemental maps and in situ O isotopic analyses of FeO-poor, olivine-rich chondrules from ordinary chondrites (OCs) to compare the conditions of chondrule formation in these two main classes of chondrites. OC chondrules show minor element (e.g., Ti, Al) zonings at both the chondrule and individual olivine grain scales. Considering the entire isotopic data set, our data define a mass-independent correlation, with olivine grains showing O isotopic variations spanning more than 40texttenthousand. Though 16O-rich relict olivine grains were identified in OC chondrules, they are much less abundant than in CC chondrules. They appear as two types : (i) those with low minor element abundances and D17O \< -15texttenthousand and (ii) those with varying minor element abundances and less negative D17O values averaging -5.5texttenthousand. The host olivine grains exhibit massdependent O isotopic variations within individual chondrules. Our results reveal that similar processes (precursor recycling and interactions between chondrule melts and a SiO- and Mg-rich gas) established the observed features of OC and CC chondrules. The mass-dependent isotopic variations recorded by host olivine grains result from kinetic effects induced by complex evaporation/recondensation processes during the gasmelt interactions. This suggests that OC chondrules formed through enhanced recycling processes, in good agreement with the lower abundances of relict olivine grains in OC chondrules compared to CC chondrules. We use the D18O = d18O ?\u{I} d17O parameter to demonstrate that there is no genetic relationship between CC and OC chondrules, suggesting limited radial transport in the protoplanetary disk. Finally, to the first order, the D18O--D17O diagram may allow the non-carbonaceous vs. carbonaceous origin of a given chondrule to be deciphered.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Chondrules are sub-millimetric spheroids that are ubiquitous in chondrites and whose formation mechanism remains elusive. Textural and oxygen isotopic characteristics of chondrules in carbonaceous chondrites (CCs) suggest that they result from the recycling of isotopically heterogeneous early-condensed precursors via gas--melt interactions. Here, we report high-resolution X-ray elemental maps and in situ O isotopic analyses of FeO-poor, olivine-rich chondrules from ordinary chondrites (OCs) to compare the conditions of chondrule formation in these two main classes of chondrites. OC chondrules show minor element (e.g., Ti, Al) zonings at both the chondrule and individual olivine grain scales. Considering the entire isotopic data set, our data define a mass-independent correlation, with olivine grains showing O isotopic variations spanning more than 40texttenthousand. Though 16O-rich relict olivine grains were identified in OC chondrules, they are much less abundant than in CC chondrules. They appear as two types : (i) those with low minor element abundances and D17O < -15texttenthousand and (ii) those with varying minor element abundances and less negative D17O values averaging -5.5texttenthousand. The host olivine grains exhibit massdependent O isotopic variations within individual chondrules. Our results reveal that similar processes (precursor recycling and interactions between chondrule melts and a SiO- and Mg-rich gas) established the observed features of OC and CC chondrules. The mass-dependent isotopic variations recorded by host olivine grains result from kinetic effects induced by complex evaporation/recondensation processes during the gasmelt interactions. This suggests that OC chondrules formed through enhanced recycling processes, in good agreement with the lower abundances of relict olivine grains in OC chondrules compared to CC chondrules. We use the D18O = d18O ?Ĭ d17O parameter to demonstrate that there is no genetic relationship between CC and OC chondrules, suggesting limited radial transport in the protoplanetary disk. Finally, to the first order, the D18O--D17O diagram may allow the non-carbonaceous vs. carbonaceous origin of a given chondrule to be deciphered. |
2020
|
Piralla, M., Marrocchi, Y., Verdier-Paoletti, M. J., Vacher, L. G., Villeneuve, J., Piani, L., Bekaert, D. V., Gounelle, M. Primordial water and dust of the Solar System: Insights from in situ oxygen measurements of CI chondrites (Article de journal) Dans: Geochimica et Cosmochimica Acta, vol. 269, p. 451–464, 2020. @article{Piralla_etal2020,
title = {Primordial water and dust of the Solar System: Insights from in situ oxygen measurements of CI chondrites},
author = {M. Piralla and Y. Marrocchi and M. J. Verdier-Paoletti and L. G. Vacher and J. Villeneuve and L. Piani and D. V. Bekaert and M. Gounelle},
doi = {10.1016/j.gca.2019.10.041},
year = {2020},
date = {2020-01-01},
journal = {Geochimica et Cosmochimica Acta},
volume = {269},
pages = {451--464},
abstract = {As the chemical compositions of CI chondrites closely resemble that of the Suntextquoterights photosphere, their oxygen isotopic compositions represent a powerful tool to constrain the origin and dynamics of dust and water ice grains in the protoplanetarydisk. However, parent-body alteration processes make straightforward estimation of the primordial isotopic compositions of CI chondritic water and anhydrous minerals difficult. In this contribution, we used in situ SIMS measurements to determinethe oxygen isotope compositions of mechanically isolated olivine and carbonate grains from the CI chondrite Orgueil and carbonates in a polished section of the CI chondrite Ivuna. Most CI olivine grains have Earth-like O isotopic compositions(D17O ≈ 0texttenthousand) plotting at the intersection of the terrestrial fractionation line and the primitive chondrule minerals line. Ca-carbonates from Orgueil and Ivuna define a trend with d17O = (0.50 textpm 0.05) x d18O + (0.9 textpm 1.4) that differs from massindependent variations observed in secondary phases of other carbonaceous chondrites. These data show that CIs are chemically solar but isotopically terrestrial for oxygen isotopes. This supports models suggesting that primordial Solar System dust was 16O-poor (D17O ≈ 0texttenthousand) relative to the 16O-rich nebular gas. Based on results, mass balance calculations reveal that the pristine O isotopic compositions of carbonaceous chondrite matrices differ significantly from the CI composition, except for CR chondrites (calculated D17O values of CM, CO, CV and CR matrices being --3.97 textpm 1.19texttenthousand, --4.33 textpm 1.45texttenthousand, --7.95textpm 1.95texttenthousand, and --0.07 textpm 1.16texttenthousand, respectively). This confirms an open chondrule-matrix system with respect to oxygen isotopes where chondrule compositions reflect complex processes of chondrule precursor recycling and gas-melt interactions. As the Mg-Si-Fe chondrule budget is also partially controlled by gas-melt interactions, the complementary formation of chondrules and matrix from a single solar-like reservoir -if it exists- require that (i) this reservoir must have been in a closed system with the gas or (ii) the gas had a CI composition to satisfy the elemental mass balance.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
As the chemical compositions of CI chondrites closely resemble that of the Suntextquoterights photosphere, their oxygen isotopic compositions represent a powerful tool to constrain the origin and dynamics of dust and water ice grains in the protoplanetarydisk. However, parent-body alteration processes make straightforward estimation of the primordial isotopic compositions of CI chondritic water and anhydrous minerals difficult. In this contribution, we used in situ SIMS measurements to determinethe oxygen isotope compositions of mechanically isolated olivine and carbonate grains from the CI chondrite Orgueil and carbonates in a polished section of the CI chondrite Ivuna. Most CI olivine grains have Earth-like O isotopic compositions(D17O ≈ 0texttenthousand) plotting at the intersection of the terrestrial fractionation line and the primitive chondrule minerals line. Ca-carbonates from Orgueil and Ivuna define a trend with d17O = (0.50 textpm 0.05) x d18O + (0.9 textpm 1.4) that differs from massindependent variations observed in secondary phases of other carbonaceous chondrites. These data show that CIs are chemically solar but isotopically terrestrial for oxygen isotopes. This supports models suggesting that primordial Solar System dust was 16O-poor (D17O ≈ 0texttenthousand) relative to the 16O-rich nebular gas. Based on results, mass balance calculations reveal that the pristine O isotopic compositions of carbonaceous chondrite matrices differ significantly from the CI composition, except for CR chondrites (calculated D17O values of CM, CO, CV and CR matrices being --3.97 textpm 1.19texttenthousand, --4.33 textpm 1.45texttenthousand, --7.95textpm 1.95texttenthousand, and --0.07 textpm 1.16texttenthousand, respectively). This confirms an open chondrule-matrix system with respect to oxygen isotopes where chondrule compositions reflect complex processes of chondrule precursor recycling and gas-melt interactions. As the Mg-Si-Fe chondrule budget is also partially controlled by gas-melt interactions, the complementary formation of chondrules and matrix from a single solar-like reservoir -if it exists- require that (i) this reservoir must have been in a closed system with the gas or (ii) the gas had a CI composition to satisfy the elemental mass balance. |
Vacher, L., Piani, L., Rigaudier, T., Thomassin, D., Florin, G., Piralla, M., Marrocchi, Y. Hydrogen in chondrites: Influence of parent body alteration and atmospheric contamination on primordial components (Article de journal) Dans: Geochimica et Cosmochimica Acta, vol. 281, p. 53–66, 2020. @article{Vacher_etal2020,
title = {Hydrogen in chondrites: Influence of parent body alteration and atmospheric contamination on primordial components},
author = {L. Vacher and L. Piani and T. Rigaudier and D. Thomassin and G. Florin and M. Piralla and Y. Marrocchi},
doi = {10.1016/j.gca.2020.05.007},
year = {2020},
date = {2020-01-01},
urldate = {2020-01-01},
journal = {Geochimica et Cosmochimica Acta},
volume = {281},
pages = {53--66},
abstract = {Hydrogen occurs at the near percent level in the most hydrated chondrites (CI and CM) attesting to the presence of waterin the asteroid-forming regions. Their H abundances and isotopic signatures are powerful proxies for deciphering the distri-bution of H in the protoplanetary disk and the origin of Earthtextquoterights water. Here, we report H contents and isotopic compositionsfor a set of carbonaceous and ordinary chondrites, including previously analyzed and new samples analyzed after the pow-dered samples were degassed under vacuum at 120textdegreeC for 48 hours to remove adsorbed atmospheric water. By comparing ourresults to literature data, we reveal that the H budgets of both H-poor and H-rich carbonaceous chondrites are largely affectedby atmospheric moisture, and that their precise quantification requires a specific pre-degassing procedure to correct for ter-restrial contamination. Our results show that indigenous H contents of CI carbonaceous chondrites usually considered themost hydrated meteorites might be almost a factor of two lower than those previously reported, with uncontaminated D/H ratios differing significantly from that of Earthtextquoterights oceans. Without pre-degassing, the H concentrations of H-poor samples(e.g., CVs chondrites) are also affected by terrestrial contamination. After correction for contamination, it appears that theamount of water in chondrites is not controlled by the matrix modal abundance, suggesting that the different chondritic par-ent bodies accreted variable amounts of water-ice grains. Our results also imply that (i) thermal metamorphism play an impor-tant role in determining the H content of both CV and ordinary chondrites but without affecting drastically their H isotopiccomposition since no clear D enrichment is observed with the increase of petrographic type and (ii) the D enrichment of ordi-nary chondrite organics does not result from the loss of isotopically light H2induced by metal oxidation but is rather linked tothe persistence of a thermally resistant D-rich component},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Hydrogen occurs at the near percent level in the most hydrated chondrites (CI and CM) attesting to the presence of waterin the asteroid-forming regions. Their H abundances and isotopic signatures are powerful proxies for deciphering the distri-bution of H in the protoplanetary disk and the origin of Earthtextquoterights water. Here, we report H contents and isotopic compositionsfor a set of carbonaceous and ordinary chondrites, including previously analyzed and new samples analyzed after the pow-dered samples were degassed under vacuum at 120textdegreeC for 48 hours to remove adsorbed atmospheric water. By comparing ourresults to literature data, we reveal that the H budgets of both H-poor and H-rich carbonaceous chondrites are largely affectedby atmospheric moisture, and that their precise quantification requires a specific pre-degassing procedure to correct for ter-restrial contamination. Our results show that indigenous H contents of CI carbonaceous chondrites usually considered themost hydrated meteorites might be almost a factor of two lower than those previously reported, with uncontaminated D/H ratios differing significantly from that of Earthtextquoterights oceans. Without pre-degassing, the H concentrations of H-poor samples(e.g., CVs chondrites) are also affected by terrestrial contamination. After correction for contamination, it appears that theamount of water in chondrites is not controlled by the matrix modal abundance, suggesting that the different chondritic par-ent bodies accreted variable amounts of water-ice grains. Our results also imply that (i) thermal metamorphism play an impor-tant role in determining the H content of both CV and ordinary chondrites but without affecting drastically their H isotopiccomposition since no clear D enrichment is observed with the increase of petrographic type and (ii) the D enrichment of ordi-nary chondrite organics does not result from the loss of isotopically light H2induced by metal oxidation but is rather linked tothe persistence of a thermally resistant D-rich component |
2019
|
Marrocchi, Y., Villeneuve, J., Jacquet, E., Piralla, M., Chaussidon, M. Rapid condensation of the first Solar System solids (Article de journal) Dans: PNAS, vol. 116, no. 47, p. 23461–23466, 2019. @article{Marrocchi_etal2019_2,
title = {Rapid condensation of the first Solar System solids},
author = {Y. Marrocchi and J. Villeneuve and E. Jacquet and M. Piralla and M. Chaussidon},
doi = {/10.1073/pnas.1912479116},
year = {2019},
date = {2019-01-01},
journal = {PNAS},
volume = {116},
number = {47},
pages = {23461--23466},
abstract = {Chondritic meteorites are composed of primitive components formed during the evolution of the Solar protoplanetary disk. The oldest of these components formed by condensation, yet little is known about their formation mechanism because of secondary heating processes that erased their primordial signature. Amoeboid Olivine Aggregates (AOAs) have never been melted and underwent minimal thermal annealing, implying they might have retained the conditions under which they condensed. We performed a multiisotope (O, Si, Mg) characterization of AOAs to constrain the conditions under which they condensed and the information they bear on the structure and evolution of the Solar protoplanetary disk. High-precision silicon isotopic measurements of 7 AOAs from weakly metamorphosed carbonaceous chondrites show large, mass-dependent, light Si isotope enrichments (--9texttenthousand \< $delta$30Si \< --1texttenthousand). Based on physical modeling of condensation within the protoplanetary disk, we attribute these isotopic compositions to the rapid condensation of AOAs over timescales of days to weeks. The same AOAs show slightly positive $delta$25Mg that suggest that Mg isotopic homogenization occurred during thermal annealing without affecting Si isotopes. Such short condensation times for AOAs are inconsistent with disk transport timescales, indicating that AOAs, and likely other high-temperature condensates, formed during brief localized high-temperature events.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Chondritic meteorites are composed of primitive components formed during the evolution of the Solar protoplanetary disk. The oldest of these components formed by condensation, yet little is known about their formation mechanism because of secondary heating processes that erased their primordial signature. Amoeboid Olivine Aggregates (AOAs) have never been melted and underwent minimal thermal annealing, implying they might have retained the conditions under which they condensed. We performed a multiisotope (O, Si, Mg) characterization of AOAs to constrain the conditions under which they condensed and the information they bear on the structure and evolution of the Solar protoplanetary disk. High-precision silicon isotopic measurements of 7 AOAs from weakly metamorphosed carbonaceous chondrites show large, mass-dependent, light Si isotope enrichments (--9texttenthousand < $delta$30Si < --1texttenthousand). Based on physical modeling of condensation within the protoplanetary disk, we attribute these isotopic compositions to the rapid condensation of AOAs over timescales of days to weeks. The same AOAs show slightly positive $delta$25Mg that suggest that Mg isotopic homogenization occurred during thermal annealing without affecting Si isotopes. Such short condensation times for AOAs are inconsistent with disk transport timescales, indicating that AOAs, and likely other high-temperature condensates, formed during brief localized high-temperature events. |
Vacher, L. G., Piralla, M., Gounelle, M., Bizzarro, M., Marrocchi, Y. Thermal evolution of hydrated asteroids inferred from oxygen isotopes (Article de journal) Dans: The Astrophysical Journal Letters, vol. 882, p. L20, 2019. @article{Vacher_etal2019,
title = {Thermal evolution of hydrated asteroids inferred from oxygen isotopes},
author = {L. G. Vacher and M. Piralla and M. Gounelle and M. Bizzarro and Y. Marrocchi},
doi = {10.3847/2041-8213/ab3bd0},
year = {2019},
date = {2019-01-01},
journal = {The Astrophysical Journal Letters},
volume = {882},
pages = {L20},
abstract = {Chondrites are fragments of unmelted asteroids that formed due to gravitational instabilities in turbulent regions of the Solar protoplanetary disk. Hydrated chondrites are common among meteorites, indicating that a substantial fraction of the rocky bodies that formed early in the solar system accreted water ice grains that subsequently melted due to heat released by the radioactive decay of 26Al. However, the thermal histories of asteroids are still largely unknown ; increased knowledge would provide fundamental information on their timing of accretion and their physical characteristics. Here we show that hydrated meteorites (CM chondrites) contain previously uncharacterized calcium carbonates with peculiar oxygen isotopic compositions ($Delta$17O��\'{E}��2.5texttenthousand), which artificially produce the massindependent trend previously reported for carbonates. Based on these isotopic data, we propose a new model to quantitatively estimate the precipitation temperatures of secondary phases (carbonates and serpentine). It reveals that chondritic secondary phases recorded a gradual increase in temperature during the extent of aqueous alteration, from −10textdegreeC to a maximum of 250textdegreeC. We also show that the thermal path of C-type asteroids is independent of the initial oxygen isotopic composition of the primordial water ice grains that they accreted. Our estimated temperatures for hydrated asteroids remain lower than those experienced by other carbonaceous chondrites, providing strong constraints for modeling the formation conditions and size distribution of water-rich asteroids, especially in anticipation of the return of samples of water-rich asteroids to Earth by the OSIRIS-REx and Hayabusa2 missions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Chondrites are fragments of unmelted asteroids that formed due to gravitational instabilities in turbulent regions of the Solar protoplanetary disk. Hydrated chondrites are common among meteorites, indicating that a substantial fraction of the rocky bodies that formed early in the solar system accreted water ice grains that subsequently melted due to heat released by the radioactive decay of 26Al. However, the thermal histories of asteroids are still largely unknown ; increased knowledge would provide fundamental information on their timing of accretion and their physical characteristics. Here we show that hydrated meteorites (CM chondrites) contain previously uncharacterized calcium carbonates with peculiar oxygen isotopic compositions ($Delta$17O��É��2.5texttenthousand), which artificially produce the massindependent trend previously reported for carbonates. Based on these isotopic data, we propose a new model to quantitatively estimate the precipitation temperatures of secondary phases (carbonates and serpentine). It reveals that chondritic secondary phases recorded a gradual increase in temperature during the extent of aqueous alteration, from −10textdegreeC to a maximum of 250textdegreeC. We also show that the thermal path of C-type asteroids is independent of the initial oxygen isotopic composition of the primordial water ice grains that they accreted. Our estimated temperatures for hydrated asteroids remain lower than those experienced by other carbonaceous chondrites, providing strong constraints for modeling the formation conditions and size distribution of water-rich asteroids, especially in anticipation of the return of samples of water-rich asteroids to Earth by the OSIRIS-REx and Hayabusa2 missions. |
