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P Rochette - One of the best experts on this subject based on the ideXlab platform.
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lut 009 an h4 s2 w4 Ordinary Chondrite meteorite from lut desert of iran
فیزیک زمین و فضا, 2015Co-Authors: Hamed Pourkhorsandi, P Rochette, Hassan Mirnejad, Jamshid HassanzadehAbstract:Lut 009 meteorite was found during a trip to Lut Desert of Iran in March,2012, at 30°20.38' N, 59°09.04' E. Chemical compositions of equilibrated olivine (Fa19.3 ± 0.5) and orthopyroxene (Fs16.7 ± 0.6) show that the meteorite sample belongs to H group of Ordinary Chondrites, while the texture (chondrule petrography and plagioclase size) suggests a petrologic type of 4. The Lut 009 has been very weakly shock altered and has a shock stage of S2. Fe-Ni is completely weathered whereas less than 5 percent of troilite is still present. Therefore, the meteorite has a weathering grade of W4. Magnetic susceptibility is log χ =4.75 (χ in 10-9 m3/kg) and, thus, consistent with a W4 H Ordinary Chondrite. Here we report description of Lut 009 in the first extended study on a meteorite from Lut Desert. Along with this sample, in-progress investigations of other meteorites from the desert will open a window into the characteristics of meteorite concentrations in this region.
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Ordinary Chondrite related giant 800 μm cosmic spherules from the transantarctic mountains antarctica
Geochimica et Cosmochimica Acta, 2011Co-Authors: C Suavet, Jérôme Gattacceca, Carole Cordier, P Rochette, L Folco, Corinne Sonzogni, D DamphofferAbstract:Abstract In order to identify the parent bodies of cosmic spherules (melted micrometeorites) with porphyritic olivine (PO) and cryptocrystalline (CC) textures, we measured the oxygen isotopic composition of 15 giant (>800 μm) cosmic spherules recovered in the Transantarctic Mountains, Antarctica, with IR-laser fluorination/mass spectrometry, and we conducted a characterization of their petrographic and magnetic properties. Samples include 6, 8 and 1 spherules of PO, CC and barred olivine (BO) textural types, respectively. Eleven spherules (∼70% of the total: 4/6 PO and 6/8 CC, and the BO spherule) are related to Ordinary Chondrites based on oxygen isotopic compositions. Olivines in Ordinary Chondrite-related spherules have compositions Fa 8.5–11.8 , they are Ni-poor to Ni-rich (0.04–1.12 wt.%), and tend to be richer in CaO than other spherules (0.10–0.17 wt.%). Ordinary-Chondrite related spherules also have high magnetite contents (∼2–12 wt.%). One PO and one CC spherules are related to previously identified 17 O-enriched cosmic spherules for which the parent body is unknown. One CC spherule has an oxygen isotopic signature relating it to CM/CR carbonaceous Chondrites. The majority of PO/CC cosmic spherules derive from Ordinary Chondrites; this result exemplifies how the texture of cosmic spherules is not only controlled by atmospheric entry heating conditions but also depends on the parent body, whether be it through orbital parameters (entry angle and velocity), or chemistry, mineralogy, or grain size of the precursor.
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Ordinary Chondrite related giant cosmic spherules
2011Co-Authors: C Suavet, Carole Cordier, P Rochette, L Folco, J Gattacceca, Corinne Sonzogni, D DamphofferAbstract:CEREGE, Aix-en-Provence, France. Micrometeorites are extraterrestrial particles smaller than ~2 mm collected on the Earth’s surface [1]. Most of them melt during atmospheric entry; they are called cosmic spherules. A previous study [2] found that all three spherules with porphyritic olivine (PO) and cryptocrystalline (CC) textures were related to Ordinary Chondrites based on their oxygen isotopic signature. Here we report the oxygen isotope compositions of 15 giant (>800 µm) cosmic spherules from the Transantarctic Mountains, Antarctica [3], including 6 PO, 8 CC and 1 barred olivine (BO) textural types [4]. Eleven spherules (~70% of them: 4/6 PO and 6/8 CC, and the BO spherule) are related to Ordinary Chondrites based on oxygen isotopic compositions. In Ordinary Chondrite-related PO spherules olivines have Fa
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experimental shock metamorphism of the l4 Ordinary Chondrite saratov induced by spherical shock waves up to 400 gpa
Meteoritics & Planetary Science, 2010Co-Authors: Jérôme Gattacceca, P Rochette, N S Bezaeva, Dmitri D Badjukov, V I Trukhin, E A Kozlov, Minoru UeharaAbstract:Abstract– We carried out shock experiments on macroscopic spherical samples of the L4 Ordinary Chondrite Saratov (natural shock stages S2–S3), using explosively generated spherical shock waves with maximum peak pressures of 400 GPa and shock-induced temperatures >800 °C (up to several thousands °C). The evolution of shock metamorphism within a radius of the spherical samples was investigated using optical and scanning electron microscopy, microprobe and magnetic analyses as well as Mossbauer spectroscopy and X-ray diffraction techniques. Petrographic analyses revealed a shock-induced formation of three different concentric petrographic zones within the shocked samples: zone of total melting (I), zone of partial melting (II), and zone of solid-state shock features (III). We found a progressive pressure-induced oxidation of Fe-Ni metal, whose degree increased with increasing shock peak pressure. The amount of FeO within zone I increased the factor of 1.4 with respect to its amount in the unshocked Saratov sample. This suggests that within zone I about 70 wt% of the initial metallic iron was oxidized, whereas magnetic analyses showed that about 10 wt% of it remained intact. This strongly supports the hypothesis that, in addition to oxidation, a migration of metallic iron from the central heavily shocked zone I toward less shocked peripheral zone took place as well (likely through shock veins where metallic droplets were observed). Magnetic analyses also showed a shock-induced transformation of tetrataenite to taenite within all shocked subsamples, resulting in magnetic softening of these subsamples (decrease in remanent coercivity). These results have important implications for extraterrestrial paleomagnetism suggesting that due to natural impact processes, the buried crustal rocks of heavily cratered solid solar system bodies can have stronger remanent magnetism than the corresponding surface rocks.
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sahara 03505 sulfide rich iron meteorite evidence for efficient segregation of sulfide rich metallic melt during high degree impact melting of an Ordinary Chondrite
Meteoritics & Planetary Science, 2009Co-Authors: Massimo Dorazio, L Folco, Marc Chaussidon, P RochetteAbstract:The Sahara 03505 meteorite is a 65 g sulfide-rich iron found in an undisclosed locality of the Sahara. It consists of roughly equal volumetric proportion of polycrystalline troilite (crystal size 1.5-7.5 mm) enclosing cellular/dendritic metallic Fe-Ni (width of the dendrite arms, ~100 m). The mineral assemblage is completed by sparse skeletal crystals of chromite, abundant droplets, 5-100 μm in size, of anhydrous Fe-, Fe-Na-, and Fe-Mn-Mg-Ca-Na-K-phosphates, tiny crystals of schreibersite, and particles of metallic Cu. The medium- to fine-grained quench texture, and cooling modeling suggest that Sahara 03505 formed through crystallization of a sulfur-rich metallic melt under rapid cooling conditions (1-4 °C s^(-1)). The low troilite/metallic Fe-Ni ratio (~0.6 by weight) shows that this liquid was generated at much higher temperatures (>1300 °C) with respect to the FeS-Fe,Ni cotectic liquids. Based on bulk chemistry and oxygen isotope composition of chromite, we propose that Sahara 03505 formed by extensive impact melting of an Ordinary Chondrite lithology, followed by the efficient segregation of the immiscible silicate and metallic liquids. The sulfur-rich metallic liquid rapidly cooled either by radiation into space as a small lump, or by conduction to a Chondrite country rock as a vein intruded into the walls of an impact crater. Sahara 03505 belongs to a small group of sulfide-rich iron meteorites which are characterized by medium- to fine-grained quench textures and by bulk chemistry that is different from the other iron meteorite groups. We propose here to use the descriptive term sulfide-irons for this meteorite group, by analogy with the stony-irons.
Jérôme Gattacceca - One of the best experts on this subject based on the ideXlab platform.
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The Piancaldoli meteorite: A forgotten primitive LL3.10 Ordinary Chondrite
Meteoritics & Planetary Science, 2020Co-Authors: Yves Marrocchi, Lydie Bonal, Jérôme Gattacceca, Laurette Piani, Pierre Beck, Jolantha Eschrig, Anne Basque, Pasquale Mario Nuccio, Richard C. Greenwood, Franco Foresta MartinAbstract:The Piancaldoli Ordinary Chondrite fell in northern Italy on August 10th 1968 and was collected the same day. Preliminary studies led to its classification as an LL 3.4 unequilibrated Ordinary Chondrite. The recent developments of new classification procedures have prompted us to design a multitechnique study for re-determining its mineralogical, petrographic, spectroscopic and chemical and isotopic features. Our results reveal that Piancaldoli is less altered than previously reported and should be reclassified as an LL 3.10 unequilibrated Ordinary Chondrite. In combination with the findings of previous studies, our data confirm the reliability of the use of Cr content variability in type II ferroan chondrule olivine as a proxy of thermal metamorphism. The Cr indicator gives consistent estimation with those inferred from Raman spectroscopy measurements and magnetic properties. The high hydrogen content of Piancaldoli also attests that Piancaldoli experienced minimal thermal metamorphism. Our results also imply that the bulk deuterium enrichment in deuterium observed in Piancaldoli (LL 3.10), Bishunpur (LL 3.15) and Semarkona (LL 3.00) is a specific signature of the most primitive unequilibrated LL Chondrites. Based on our results, we propose that Piancaldoli corresponds to the second least altered fall unequilibrated Ordinary Chondrite after Semarkona. This shows that meteorite collections worldwide are fundamental resources for studying the formation conditions and evolution our solar system.
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The Piancaldoli meteorite: A forgotten primitive LL3.10 Ordinary Chondrite
Meteoritics and Planetary Science, 2020Co-Authors: Yves Marrocchi, Lydie Bonal, Jérôme Gattacceca, Laurette Piani, Pierre Beck, Richard Greenwood, Jolantha Eschrig, Anne Basque, Pasquale Mario Nuccio, Franco Foresta MartinAbstract:The Piancaldoli Ordinary Chondrite fell in northern Italy on August 10, 1968. Preliminary studies led to its classification as an LL3.4 unequilibrated Ordinary Chondrite. However, recent developments in classification procedures have prompted us to re‐examine its mineralogical, petrographic, spectroscopic, chemical, and isotopic features in a multi‐technique study. Raman spectra and magnetic properties indicate that Piancaldoli experienced minimal thermal metamorphism, consistent with its high bulk hydrogen content and the Cr contents of ferroan olivines in its type II chondrules. In combination with findings of previous studies, our data thus confirm the variability of Cr contents in ferroan olivines in type II chondrules as a proxy of thermal metamorphism. Furthermore, our results reveal that Piancaldoli is less altered than previously reported and should be reclassified as an LL3.10 unequilibrated Ordinary Chondrite. Our results also imply that the bulk deuterium enrichment, as observed in Piancaldoli (LL3.10), Bishunpur (LL3.15), and Semarkona (LL3.00), is a specific signature of the most primitive unequilibrated Ordinary Chondrites. Based on our results, we propose that, to date, Piancaldoli is the second least‐altered unequilibrated Ordinary Chondrite fall after Semarkona. This work reiterates the importance of meteorite collections worldwide as fundamental resources for studying the formation conditions and evolution of our solar system
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Ordinary Chondrite related giant 800 μm cosmic spherules from the transantarctic mountains antarctica
Geochimica et Cosmochimica Acta, 2011Co-Authors: C Suavet, Jérôme Gattacceca, Carole Cordier, P Rochette, L Folco, Corinne Sonzogni, D DamphofferAbstract:Abstract In order to identify the parent bodies of cosmic spherules (melted micrometeorites) with porphyritic olivine (PO) and cryptocrystalline (CC) textures, we measured the oxygen isotopic composition of 15 giant (>800 μm) cosmic spherules recovered in the Transantarctic Mountains, Antarctica, with IR-laser fluorination/mass spectrometry, and we conducted a characterization of their petrographic and magnetic properties. Samples include 6, 8 and 1 spherules of PO, CC and barred olivine (BO) textural types, respectively. Eleven spherules (∼70% of the total: 4/6 PO and 6/8 CC, and the BO spherule) are related to Ordinary Chondrites based on oxygen isotopic compositions. Olivines in Ordinary Chondrite-related spherules have compositions Fa 8.5–11.8 , they are Ni-poor to Ni-rich (0.04–1.12 wt.%), and tend to be richer in CaO than other spherules (0.10–0.17 wt.%). Ordinary-Chondrite related spherules also have high magnetite contents (∼2–12 wt.%). One PO and one CC spherules are related to previously identified 17 O-enriched cosmic spherules for which the parent body is unknown. One CC spherule has an oxygen isotopic signature relating it to CM/CR carbonaceous Chondrites. The majority of PO/CC cosmic spherules derive from Ordinary Chondrites; this result exemplifies how the texture of cosmic spherules is not only controlled by atmospheric entry heating conditions but also depends on the parent body, whether be it through orbital parameters (entry angle and velocity), or chemistry, mineralogy, or grain size of the precursor.
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experimental shock metamorphism of the l4 Ordinary Chondrite saratov induced by spherical shock waves up to 400 gpa
Meteoritics & Planetary Science, 2010Co-Authors: Jérôme Gattacceca, P Rochette, N S Bezaeva, Dmitri D Badjukov, V I Trukhin, E A Kozlov, Minoru UeharaAbstract:Abstract– We carried out shock experiments on macroscopic spherical samples of the L4 Ordinary Chondrite Saratov (natural shock stages S2–S3), using explosively generated spherical shock waves with maximum peak pressures of 400 GPa and shock-induced temperatures >800 °C (up to several thousands °C). The evolution of shock metamorphism within a radius of the spherical samples was investigated using optical and scanning electron microscopy, microprobe and magnetic analyses as well as Mossbauer spectroscopy and X-ray diffraction techniques. Petrographic analyses revealed a shock-induced formation of three different concentric petrographic zones within the shocked samples: zone of total melting (I), zone of partial melting (II), and zone of solid-state shock features (III). We found a progressive pressure-induced oxidation of Fe-Ni metal, whose degree increased with increasing shock peak pressure. The amount of FeO within zone I increased the factor of 1.4 with respect to its amount in the unshocked Saratov sample. This suggests that within zone I about 70 wt% of the initial metallic iron was oxidized, whereas magnetic analyses showed that about 10 wt% of it remained intact. This strongly supports the hypothesis that, in addition to oxidation, a migration of metallic iron from the central heavily shocked zone I toward less shocked peripheral zone took place as well (likely through shock veins where metallic droplets were observed). Magnetic analyses also showed a shock-induced transformation of tetrataenite to taenite within all shocked subsamples, resulting in magnetic softening of these subsamples (decrease in remanent coercivity). These results have important implications for extraterrestrial paleomagnetism suggesting that due to natural impact processes, the buried crustal rocks of heavily cratered solid solar system bodies can have stronger remanent magnetism than the corresponding surface rocks.
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magnetic properties of a freshly fallen ll Ordinary Chondrite the bensour meteorite
Physics of the Earth and Planetary Interiors, 2003Co-Authors: Jérôme Gattacceca, P Rochette, Michele BourotdeniseAbstract:Abstract A comprehensive rock magnetic, magnetic anisotropy and paleomagnetic study has been undertaken in the brecciated LL6 Bensour Ordinary Chondrite, a few months only after its fall on Earth. Microscopic observations and electronic microprobe analyses indicate the presence of Ni-rich taenite, tetrataenite and rare Co-rich kamacite. Tetrataenite is the main carrier of remanence. Magnetization and anisotropy measurements were performed on mutually oriented 125 mm 3 sub-samples. A very strong coherent susceptibility and remanence anisotropy is evidenced and interpreted as due to the large impact responsible for the post-metamorphic compaction of this brecciated material and disruption of the parent body. We show that the acquisition of remanent magnetization postdates metamorphism on the parent body and predates the entering of the meteorite in Earth’s atmosphere. Three components of magnetization could be isolated. A soft coherent component is closely related to the anisotropy of the meteorite and is interpreted as a shock remanent magnetization acquired during the same large impact on the parent body. Two harder components show random directions at a few mm scale. This randomness is attributed either to the formation mechanism of tetrataenite or to post-metamorphic brecciation. All components are likely acquired in very low (≈μT) to null ambient magnetic field, as demonstrated by comparison with demagnetization behavior of isothermal remanent magnetization. Two other LL6 meteorites, Kilabo and St-Mesmin, have also been studied for comparison with Bensour.
Larry R Nittler - One of the best experts on this subject based on the ideXlab platform.
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aluminum calcium and titanium rich oxide stardust in Ordinary Chondrite meteorites
The Astrophysical Journal, 2008Co-Authors: Larry R Nittler, Conel Od M Alexander, R Gallino, P Hoppe, Ann N Nguyen, Frank J Stadermann, Ernst ZinnerAbstract:We report O-, Al-Mg-, K-, Ca-, and Ti-isotopic data for a total of 96 presolar oxide grains found in residues of several unequilibrated Ordinary Chondrite meteorites. Identified grain types include Al2O3 ,M gAl2O4, hibonite (CaAl12O19), and Ti oxide. This work greatly increases the presolar hibonite database, and is the first report of presolarTioxide.O-isotopiccompositionsof thegrainsspanpreviouslyobservedrangesandindicateanoriginin red giant and asymptotic giant branch (AGB) stars of low mass (<2.5 M� ) for most grains. Cool bottom processing in the parent AGB stars is required to explain isotopic compositions of many grains. Potassium-41 enrichments in hibonite grains are attributable to in situ decay of now-extinct 41 Ca. Inferred initial 41 Ca/ 40 Ca ratios are in good agreement with model predictionsfor low-mass AGB star envelopes,provided that ionizationsuppresses 41 Cadecay. Stable Mg and Ca isotopic ratios of most of the hibonite grains reflect primarily the initial compositions of the parent starsandaregenerallyconsistentwithexpectationsforGalacticchemicalevolution,butrequiresomelocalinterstellar chemical inhomogeneity. Very high 17 O/ 16 Oo r 25 Mg/ 24 Mg ratios suggest an origin for some grains in binary star systemswheremasstransferfromanevolvedcompanionhasalteredtheparentstarcompositions.Asupernovaorigin for the hitherto enigmatic 18 O-rich Group 4 grains is strongly supported by multielement isotopic data for two grains. The Group 4 data are consistent with an origin in a single supernova in which variable amounts of material from the deep 16 O-rich interior mixed with a unique end-member mixture of the outer layers. The Ti oxide grains primarily formed in low-mass AGB stars. They are smaller and rarer than presolar Al2O3, reflecting the lower abundance of Ti than Al in AGB envelopes. Subject headingg dust, extinction — Galaxy: evolution — nuclear reactions, nucleosynthesis, abundances — stars: AGB and post-AGB — supernovae: general
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aluminum calcium and titanium rich oxide stardust in Ordinary Chondrite meteorites
arXiv: Astrophysics, 2008Co-Authors: Larry R Nittler, Conel Od M Alexander, R Gallino, P Hoppe, Ann N Nguyen, Frank J Stadermann, Ernst ZinnerAbstract:We report isotopic data for a total of 96 presolar oxide grains found in residues of several unequilibrated Ordinary Chondrite meteorites. Identified grain types include Al2O3, MgAl2O4, hibonite (CaAl12O19) and Ti oxide. This work greatly increases the presolar hibonite database, and is the first report of presolar Ti oxide. O-isotopic compositions of the grains span previously observed ranges and indicate an origin in red giant and asymptotic giant branch (AGB) stars of low mass (<2.5 MSun) for most grains. Cool bottom processing in the parent AGB stars is required to explain isotopic compositions of many grains. Potassium-41 enrichments in hibonite grains are attributable to in situ decay of now-extinct 41Ca. Inferred initial 41Ca/40Ca ratios are in good agreement with model predictions for low-mass AGB star envelopes, provided that ionization suppresses 41Ca decay. Stable Mg and Ca isotopic ratios of most of the hibonite grains reflect primarily the initial compositions of the parent stars and are generally consistent with expectations for Galactic chemical evolution, but require some local interstellar chemical inhomogeneity. Very high 17O/16O or 25Mg/24Mg ratios suggest an origin for some grains in binary star systems where mass transfer from an evolved companion has altered the parent star compositions. A supernova origin for the hitherto enigmatic 18O-rich Group 4 grains is strongly supported by multi-element isotopic data for two grains. The Group 4 data are consistent with an origin in a single supernova in which variable amounts of material from the deep 16O-rich interior mixed with a unique end-member mixture of the outer layers. The Ti oxide grains primarily formed in low-mass AGB stars. They are smaller and rarer than presolar Al2O3, reflecting the lower abundance of Ti than Al in AGB envelopes.
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minor element evidence that asteroid 433 eros is a space weathered Ordinary Chondrite parent body
Icarus, 2006Co-Authors: C. N. Foley, M. R. M. Brown, T. J. Mccoy, L. F. Lim, Larry R Nittler, R Starr, J I TrombkaAbstract:Abstract The NEAR mission to 433 Eros provided detailed data on the geology, mineralogy, and chemistry of this S-class asteroid [McCoy, T.J., Robinson, M.S., Nittler, L.R., Burbine, T.H., 2002. Chem. Erde 62, 89–121; Cheng, A.F., 1997. Space Sci. Rev. 82, 3–29] with a key science goal of understanding the relationship between asteroids and meteorites [Cheng, A.F., 1997. Space Sci. Rev. 82, 3–29; Gaffey, M.J., Burbine, T.H., Piatek, J.L., Reed, K.L., Chaky, D.A., Bell, J.F., Brown, R.H., 1993a. Icarus 106, 573–602]. Previously reported major element data revealed a bulk surface similar to that of Ordinary Chondrites, with the notable exception of sulfur, which was highly depleted [Trombka, J.I., and 23 colleagues, 2000. Science 289, 2101–2105; Nittler, L.R., and 14 colleagues, 2001. Meteorit. Planet. Sci. 36, 1673–1695]. The origin of this sulfur deficiency, and hence the fundamental nature of the asteroid's surface, has remained controversial. We report a new analysis of NEAR X-ray spectrometer data, indicating that Eros has Cr/Fe, Mn/Fe, and Ni/Fe ratios similar to Ordinary Chondrite meteorites of type LL or L. Chondritic levels of Cr, Mn, and Ni argue strongly against a partial melting explanation for the sulfur depletion. Instead, our results provide definitive evidence that Eros is a primitive body with composition and mineralogy similar to Ordinary Chondrites, but with a surface heavily modified by interactions with the solar wind and micrometeorites, processes collectively termed space weathering.
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interstellar oxide grains from the tieschitz Ordinary Chondrite
Nature, 1994Co-Authors: Larry R Nittler, C Od M Alexander, X Gao, R M Walker, Ernst ZinnerAbstract:MOST material in the Solar System has an isotopic composition that represents an average of the different stars that contributed material to the protostellar cloud. Primitive meteorites, on the other hand, preserve grains that retain the isotopic signatures of their individual stellar sources1 and thus provide valuable insight into stellar and galactic evolution, nucleosynthesis, and solar nebular processes. A large number of pre-solar silicon carbide, graphite and diamond grains have now been isolated1,2, but only three interstellar oxide grains have hitherto been recovered3–7, even though oxygen-rich stars are believed to be the dominant source of dust in the Galaxy8,9. We report here the isolation of 21 interstellar oxide grains from the Tieschitz meteorite. The grains exhibit a wide range of oxygen isotope compositions, indicating that they originated in several distinct stellar sources having different masses and initial compositions. There is also evidence for the presence of the short-lived radionuclide 26A1 in nine of the grains at the time they formed. Although the isotopic compositions of many of the grains are consistent with both observations and theoretical models of oxygen-rich red giant stars, a significant fraction have no observed stellar counterpart.
Ernst Zinner - One of the best experts on this subject based on the ideXlab platform.
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aluminum calcium and titanium rich oxide stardust in Ordinary Chondrite meteorites
The Astrophysical Journal, 2008Co-Authors: Larry R Nittler, Conel Od M Alexander, R Gallino, P Hoppe, Ann N Nguyen, Frank J Stadermann, Ernst ZinnerAbstract:We report O-, Al-Mg-, K-, Ca-, and Ti-isotopic data for a total of 96 presolar oxide grains found in residues of several unequilibrated Ordinary Chondrite meteorites. Identified grain types include Al2O3 ,M gAl2O4, hibonite (CaAl12O19), and Ti oxide. This work greatly increases the presolar hibonite database, and is the first report of presolarTioxide.O-isotopiccompositionsof thegrainsspanpreviouslyobservedrangesandindicateanoriginin red giant and asymptotic giant branch (AGB) stars of low mass (<2.5 M� ) for most grains. Cool bottom processing in the parent AGB stars is required to explain isotopic compositions of many grains. Potassium-41 enrichments in hibonite grains are attributable to in situ decay of now-extinct 41 Ca. Inferred initial 41 Ca/ 40 Ca ratios are in good agreement with model predictionsfor low-mass AGB star envelopes,provided that ionizationsuppresses 41 Cadecay. Stable Mg and Ca isotopic ratios of most of the hibonite grains reflect primarily the initial compositions of the parent starsandaregenerallyconsistentwithexpectationsforGalacticchemicalevolution,butrequiresomelocalinterstellar chemical inhomogeneity. Very high 17 O/ 16 Oo r 25 Mg/ 24 Mg ratios suggest an origin for some grains in binary star systemswheremasstransferfromanevolvedcompanionhasalteredtheparentstarcompositions.Asupernovaorigin for the hitherto enigmatic 18 O-rich Group 4 grains is strongly supported by multielement isotopic data for two grains. The Group 4 data are consistent with an origin in a single supernova in which variable amounts of material from the deep 16 O-rich interior mixed with a unique end-member mixture of the outer layers. The Ti oxide grains primarily formed in low-mass AGB stars. They are smaller and rarer than presolar Al2O3, reflecting the lower abundance of Ti than Al in AGB envelopes. Subject headingg dust, extinction — Galaxy: evolution — nuclear reactions, nucleosynthesis, abundances — stars: AGB and post-AGB — supernovae: general
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aluminum calcium and titanium rich oxide stardust in Ordinary Chondrite meteorites
arXiv: Astrophysics, 2008Co-Authors: Larry R Nittler, Conel Od M Alexander, R Gallino, P Hoppe, Ann N Nguyen, Frank J Stadermann, Ernst ZinnerAbstract:We report isotopic data for a total of 96 presolar oxide grains found in residues of several unequilibrated Ordinary Chondrite meteorites. Identified grain types include Al2O3, MgAl2O4, hibonite (CaAl12O19) and Ti oxide. This work greatly increases the presolar hibonite database, and is the first report of presolar Ti oxide. O-isotopic compositions of the grains span previously observed ranges and indicate an origin in red giant and asymptotic giant branch (AGB) stars of low mass (<2.5 MSun) for most grains. Cool bottom processing in the parent AGB stars is required to explain isotopic compositions of many grains. Potassium-41 enrichments in hibonite grains are attributable to in situ decay of now-extinct 41Ca. Inferred initial 41Ca/40Ca ratios are in good agreement with model predictions for low-mass AGB star envelopes, provided that ionization suppresses 41Ca decay. Stable Mg and Ca isotopic ratios of most of the hibonite grains reflect primarily the initial compositions of the parent stars and are generally consistent with expectations for Galactic chemical evolution, but require some local interstellar chemical inhomogeneity. Very high 17O/16O or 25Mg/24Mg ratios suggest an origin for some grains in binary star systems where mass transfer from an evolved companion has altered the parent star compositions. A supernova origin for the hitherto enigmatic 18O-rich Group 4 grains is strongly supported by multi-element isotopic data for two grains. The Group 4 data are consistent with an origin in a single supernova in which variable amounts of material from the deep 16O-rich interior mixed with a unique end-member mixture of the outer layers. The Ti oxide grains primarily formed in low-mass AGB stars. They are smaller and rarer than presolar Al2O3, reflecting the lower abundance of Ti than Al in AGB envelopes.
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interstellar oxide grains from the tieschitz Ordinary Chondrite
Nature, 1994Co-Authors: Larry R Nittler, C Od M Alexander, X Gao, R M Walker, Ernst ZinnerAbstract:MOST material in the Solar System has an isotopic composition that represents an average of the different stars that contributed material to the protostellar cloud. Primitive meteorites, on the other hand, preserve grains that retain the isotopic signatures of their individual stellar sources1 and thus provide valuable insight into stellar and galactic evolution, nucleosynthesis, and solar nebular processes. A large number of pre-solar silicon carbide, graphite and diamond grains have now been isolated1,2, but only three interstellar oxide grains have hitherto been recovered3–7, even though oxygen-rich stars are believed to be the dominant source of dust in the Galaxy8,9. We report here the isolation of 21 interstellar oxide grains from the Tieschitz meteorite. The grains exhibit a wide range of oxygen isotope compositions, indicating that they originated in several distinct stellar sources having different masses and initial compositions. There is also evidence for the presence of the short-lived radionuclide 26A1 in nine of the grains at the time they formed. Although the isotopic compositions of many of the grains are consistent with both observations and theoretical models of oxygen-rich red giant stars, a significant fraction have no observed stellar counterpart.
L Folco - One of the best experts on this subject based on the ideXlab platform.
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Ordinary Chondrite related giant 800 μm cosmic spherules from the transantarctic mountains antarctica
Geochimica et Cosmochimica Acta, 2011Co-Authors: C Suavet, Jérôme Gattacceca, Carole Cordier, P Rochette, L Folco, Corinne Sonzogni, D DamphofferAbstract:Abstract In order to identify the parent bodies of cosmic spherules (melted micrometeorites) with porphyritic olivine (PO) and cryptocrystalline (CC) textures, we measured the oxygen isotopic composition of 15 giant (>800 μm) cosmic spherules recovered in the Transantarctic Mountains, Antarctica, with IR-laser fluorination/mass spectrometry, and we conducted a characterization of their petrographic and magnetic properties. Samples include 6, 8 and 1 spherules of PO, CC and barred olivine (BO) textural types, respectively. Eleven spherules (∼70% of the total: 4/6 PO and 6/8 CC, and the BO spherule) are related to Ordinary Chondrites based on oxygen isotopic compositions. Olivines in Ordinary Chondrite-related spherules have compositions Fa 8.5–11.8 , they are Ni-poor to Ni-rich (0.04–1.12 wt.%), and tend to be richer in CaO than other spherules (0.10–0.17 wt.%). Ordinary-Chondrite related spherules also have high magnetite contents (∼2–12 wt.%). One PO and one CC spherules are related to previously identified 17 O-enriched cosmic spherules for which the parent body is unknown. One CC spherule has an oxygen isotopic signature relating it to CM/CR carbonaceous Chondrites. The majority of PO/CC cosmic spherules derive from Ordinary Chondrites; this result exemplifies how the texture of cosmic spherules is not only controlled by atmospheric entry heating conditions but also depends on the parent body, whether be it through orbital parameters (entry angle and velocity), or chemistry, mineralogy, or grain size of the precursor.
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Ordinary Chondrite related giant cosmic spherules
2011Co-Authors: C Suavet, Carole Cordier, P Rochette, L Folco, J Gattacceca, Corinne Sonzogni, D DamphofferAbstract:CEREGE, Aix-en-Provence, France. Micrometeorites are extraterrestrial particles smaller than ~2 mm collected on the Earth’s surface [1]. Most of them melt during atmospheric entry; they are called cosmic spherules. A previous study [2] found that all three spherules with porphyritic olivine (PO) and cryptocrystalline (CC) textures were related to Ordinary Chondrites based on their oxygen isotopic signature. Here we report the oxygen isotope compositions of 15 giant (>800 µm) cosmic spherules from the Transantarctic Mountains, Antarctica [3], including 6 PO, 8 CC and 1 barred olivine (BO) textural types [4]. Eleven spherules (~70% of them: 4/6 PO and 6/8 CC, and the BO spherule) are related to Ordinary Chondrites based on oxygen isotopic compositions. In Ordinary Chondrite-related PO spherules olivines have Fa
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sahara 03505 sulfide rich iron meteorite evidence for efficient segregation of sulfide rich metallic melt during high degree impact melting of an Ordinary Chondrite
Meteoritics & Planetary Science, 2009Co-Authors: Massimo Dorazio, L Folco, Marc Chaussidon, P RochetteAbstract:The Sahara 03505 meteorite is a 65 g sulfide-rich iron found in an undisclosed locality of the Sahara. It consists of roughly equal volumetric proportion of polycrystalline troilite (crystal size 1.5-7.5 mm) enclosing cellular/dendritic metallic Fe-Ni (width of the dendrite arms, ~100 m). The mineral assemblage is completed by sparse skeletal crystals of chromite, abundant droplets, 5-100 μm in size, of anhydrous Fe-, Fe-Na-, and Fe-Mn-Mg-Ca-Na-K-phosphates, tiny crystals of schreibersite, and particles of metallic Cu. The medium- to fine-grained quench texture, and cooling modeling suggest that Sahara 03505 formed through crystallization of a sulfur-rich metallic melt under rapid cooling conditions (1-4 °C s^(-1)). The low troilite/metallic Fe-Ni ratio (~0.6 by weight) shows that this liquid was generated at much higher temperatures (>1300 °C) with respect to the FeS-Fe,Ni cotectic liquids. Based on bulk chemistry and oxygen isotope composition of chromite, we propose that Sahara 03505 formed by extensive impact melting of an Ordinary Chondrite lithology, followed by the efficient segregation of the immiscible silicate and metallic liquids. The sulfur-rich metallic liquid rapidly cooled either by radiation into space as a small lump, or by conduction to a Chondrite country rock as a vein intruded into the walls of an impact crater. Sahara 03505 belongs to a small group of sulfide-rich iron meteorites which are characterized by medium- to fine-grained quench textures and by bulk chemistry that is different from the other iron meteorite groups. We propose here to use the descriptive term sulfide-irons for this meteorite group, by analogy with the stony-irons.