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3. A 4565 Myr old andesite from an extinct chondritic protoplanet

Author

Barrat, Jean-Alix, Chaussidon, Marc, Yamaguchi, Akira, Beck, Pierre, Villeneuve, Johan, Byrne, David J., Broadley, Michael W., and Marty, Bernard

Subjects
Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Astrophysics of Galaxies, Physics - Geophysics
Abstract

The age of iron meteorites implies that accretion of protoplanets began during the first millions of years of the solar system. Due to the heat generated by 26Al decay, many early protoplanets were fully differentiated with an igneous crust produced during the cooling of a magma ocean and the segregation at depth of a metallic core. The formation and nature of the primordial crust generated during the early stages of melting is poorly understood, due in part to the scarcity of available samples. The newly discovered meteorite Erg Chech 002 (EC 002) originates from one such primitive igneous crust and has an andesite bulk composition. It derives from the partial melting of a noncarbonaceous chondritic reservoir, with no depletion in alkalis relative to the Sun photosphere and at a high degree of melting of around 25 percents. Moreover, EC 002 is, to date, the oldest known piece of an igneous crust with a 26Al-26Mg crystallization age of 4,565.0 million years (My). Partial melting took place at 1,220 C up to several hundred kyr before, implying an accretion of the EC 002 parent body ca. 4,566 My ago. Protoplanets covered by andesitic crusts were probably frequent. However, no asteroid shares the spectral features of EC 002, indicating that almost all of these bodies have disappeared, either because they went on to form the building blocks of larger bodies or planets or were simply destroyed.

Published
2021
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14. Heterogeneous nature of the carbonaceous chondrite breccia Aguas Zarcas – Cosmochemical characterization and origin of new carbonaceous chondrite lithologies

Author

Kerraouch, Imene, Kebukawa, Yoko, Bischoff, Addi, Zolensky, Michael E., Wölfer, Elias, Hellmann, Jan L., Ito, Motoo, King, Ashley, Trieloff, Mario, Barrat, Jean-Alix, Schmitt-Kopplin, Phillipe, Pack, Andreas, Patzek, Markus, Hanna, Romy D., Fockenberg, Thomas, Marrocchi, Yves, Fries, Marc, Mathurin, Jérémie, Dartois, Emmanuel, Duprat, Jean, Engrand, Cécile, Deniset, Ariane, Dazzi, Alexandre, Kiryu, Kento, Igisu, Motoko, Shibuya, Takazo, Wakabayashi, Daisuke, Yamashita, Shohei, Takeichi, Yasuo, Takahashi, Yoshio, Ohigashi, Takuji, Kodama, Yu, and Kondo, Masashi

Published
2022
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16. Northwest Africa 5958: a weakly altered CM-related ungrouped chondrite, not a CI3

Author

Jacquet, Emmanuel, Barrat, Jean-Alix, Beck, Pierre, Caste, Florent, Gattacceca, Jérôme, Sonzogni, Corinne, and Gounelle, Matthieu

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

Northwest Africa (NWA) 5958 is a carbonaceous chondrite found in Morocco in 2009. Preliminary chemical and isotopic data leading to its initial classification as C3.0 ungrouped have prompted us to conduct a multi-technique study of this meteorite and present a general description here. The petrography and chemistry of NWA 5958 is most similar to a CM chondrite, with a low degree of aqueous alteration, apparently under oxidizing conditions, and evidence of a second, limited alteration episode manifested by alteration fronts. The oxygen isotopic composition, with $\Delta^{17}$O = -4.3 $\permil$, is more 16O-rich than all CM chondrites, indicating, along with other compositional arguments, a separate parent body of origin. We suggest that NWA 5958 be reclassified as an ungrouped carbonaceous chondrite related to the CM group., Comment: 32 pages, 12 figures

Published
2017
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19. The old, unique C1 chondrite Flensburg – Insight into the first processes of aqueous alteration, brecciation, and the diversity of water-bearing parent bodies and lithologies

Author

Bischoff, Addi, Alexander, Conel M. O'D., Barrat, Jean-Alix, Burkhardt, Christoph, Busemann, Henner, Degering, Detlev, Di Rocco, Tommaso, Fischer, Meike, Fockenberg, Thomas, Foustoukos, Dionysis I., Gattacceca, Jérôme, Godinho, Jose R.A., Harries, Dennis, Heinlein, Dieter, Hellmann, Jan L., Hertkorn, Norbert, Holm, Anja, Jull, A.J. Timothy, Kerraouch, Imene, King, Ashley J., Kleine, Thorsten, Koll, Dominik, Lachner, Johannes, Ludwig, Thomas, Merchel, Silke, Mertens, Cornelia A.K., Morino, Précillia, Neumann, Wladimir, Pack, Andreas, Patzek, Markus, Pavetich, Stefan, Reitze, Maximilian P., Rüfenacht, Miriam, Rugel, Georg, Schmidt, Charlotte, Schmitt-Kopplin, Philippe, Schönbächler, Maria, Trieloff, Mario, Wallner, Anton, Wimmer, Karl, and Wölfer, Elias

Published
2021
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23. Cosmic pears from the Havelland (Germany): Ribbeck, the twelfth recorded aubrite fall in history.

Author

Bischoff, Addi, Patzek, Markus, Barrat, Jean‐Alix, Berndt, Jasper, Busemann, Henner, Degering, Detlev, Di Rocco, Tommaso, Ek, Mattias, Harries, Dennis, Godinho, Jose R. A., Heinlein, Dieter, Kriele, Armin, Krietsch, Daniela, Maden, Colin, Marchhart, Oscar, Marshal, Rachael M., Martschini, Martin, Merchel, Silke, Möller, Andreas, and Pack, Andreas

Subjects
SMALL solar system bodies, PEARS, METAL sulfides, ATMOSPHERE, COSMIC rays, ASTEROIDS
Abstract

In 1889 the German poet and novelist Theodor Fontane wrote the popular literary ballad "Herr von Ribbeck auf Ribbeck im Havelland." The Squire von Ribbeck is described as a gentle and generous person, who often gives away pears from his pear trees to children passing by and continued donating pears after his death. Now, 135 years later the rock called Ribbeck is giving us insight into processes that happened 4.5 billion years ago. The meteorite Ribbeck (official find location: 52°37′15″N, 12°45′40″E) fell January 21, 2024, and has been classified as a brecciated aubrite. This meteoroid actually entered the Earth's atmosphere at 00:32:38 UTC over Brandenburg, west of Berlin, and the corresponding fireball was recorded by professional all sky and video cameras. More than 200 pieces (two proved by radionuclide analysis to belong to this fresh fall) were recovered totaling about 1.8 kg. Long‐lived radionuclide and noble gas data are consistent with long cosmic ray exposure (55–62 Ma) and a preatmospheric radius of Ribbeck between 20 and 30 cm. The heavily brecciated aubrite consists of major (76 ± 3 vol%) coarse‐grained FeO‐free enstatite (En99.1Fs<0.04Wo0.9), with a significant abundance (15.0 ± 2.5 vol%) of albitic plagioclase (Ab95.3 An2.0Or2.7), minor forsterite (5.5 ± 1.5 vol%; Fo99.9) and 3.5 ± 1.0 vol% of opaque phases (mainly sulfides and metals) with traces of nearly FeO‐free diopside (En53.2Wo46.8) and K‐feldspar (Ab4.6Or95.4). The rock has a shock degree of S3 (U‐S3), and terrestrial weathering has affected metals and sulfides, resulting in the brownish appearance of rock pieces and the partial destruction of certain sulfides already within days after the fall. The bulk chemical data confirm the feldspar‐bearing aubritic composition. Ribbeck is closely related to the aubrite Bishopville. Ribbeck does not contain solar wind implanted gases and is a fragmental breccia. Concerning the Ti‐ and O‐isotope compositions, the data are similar to those of other aubrites. They are also similar to E chondrites and fall close to the data point for the bulk silicate Earth (BSE). Before the Ribbeck meteoroid entered Earth's atmosphere, it was observed in space as asteroid 2024 BX1. The aphelion distance of 2024 BX1's orbit lies in the innermost region of the asteroid belt, which is populated by the Hungaria family of minor planets characterized by their E/X‐type taxonomy and considered as the likely source of aubrites. The spectral comparison of an average large‐scale emission spectrum of Mercury converted into reflectance and of the Ribbeck meteorite spectrum does not show any meaningful similarities. [ABSTRACT FROM AUTHOR]

Published
2024
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24. The anomalous polymict ordinary chondrite breccia of Elmshorn (H3‐6)—Late reaccretion after collision between two ordinary chondrite parent bodies, complete disruption, and mixing possibly about 2.8 Gyr ago.

Author

Bischoff, Addi, Patzek, Markus, Alosius, Romain M. L., Barrat, Jean‐Alix, Berndt, Jasper, Busemann, Henner, Degering, Detlev, Di Rocco, Tommaso, Ek, Mattias, Gattacceca, Jérôme, Godinho, Jose R. A., Heinlein, Dieter, Krietsch, Daniela, Maden, Colin, Marchhart, Oscar, Martschini, Martin, Merchel, Silke, Pack, Andreas, Peters, Stefan, and Rüfenacht, Miriam

Subjects
STONE, NOBLE gases, MAGNETIC susceptibility, COSMIC rays, ISOTOPIC analysis, CHONDRITES, CARBONACEOUS chondrites (Meteorites), OXYGEN isotopes
Abstract

Elmshorn fell April 25, 2023, about 30 km northwest of the city of Hamburg (Germany). Shortly after the fall, 21 pieces were recovered totaling a mass of 4277 g. Elmshorn is a polymict and anomalous H3‐6 chondritic, fragmental breccia. The rock is a mixture of typical H chondrite lithologies and clasts of intermediate H/L (or L, based on magnetic properties) chondrite origin. In some of the 21 pieces, the H chondrite lithologies dominate, while in others the H/L (or L) chondrite components are prevalent. The H/L chondrite assignment of these components is based on the mean composition of their olivines in equilibrated type 4 fragments (~Fa21–22). The physical properties like density (3.34 g cm−3) and magnetic susceptibility (logχ <5.0, with χ in 10−9 m3 kg−1) are typical for L chondrites, which is inconsistent with the oxygen isotope compositions: all eight O isotope analyses from two different fragments clearly fall into the H chondrite field. Thus, the fragments found in the strewn field vary in mineralogy, mineral chemistry, and physical properties but not in O isotope characteristics. The sample most intensively studied belongs to the stones dominated by H chondrite lithologies. The chemical composition and nucleosynthetic Cr and Ti isotope data are typical for ordinary chondrites. The noble gases in Elmshorn represent a mixture between cosmogenic, radiogenic, and primordially trapped noble gases, while a solar wind component can be excluded. Because the chondritic rock of Elmshorn contains (a) H chondrite parent body interior materials (of types 5 and 6), (b) chondrite parent body near‐surface materials (of types 3 and 4), (c) fragments of an H/L chondrite (dominant in many stones), (d) shock‐darkened fragments, and (e) clasts of various types of impact melts but no solar wind‐implanted noble gases, the different components cannot have been part of a parent body regolith. The most straightforward explanation is that the fragmental breccia of Elmshorn represents a reaccreted rock after a catastrophic collision between an H chondrite parent body and another body with H/L (or L) chondrite characteristics but with deviating O isotope values (i.e. that of H chondrites), complete disruption of the bodies, mixing, and reassembly. This is the only straightforward way that the implantation of solar wind gases could have been avoided in this kind of complex breccia. The gas retention ages of about 2.8 Gyr possibly indicate the closure time after the catastrophic collision between H and H/L (or L) chondrite parent bodies, while the cosmic ray exposure age for Elmshorn, which had a preatmospheric radius of 25–40 cm, is ~17–20 Myr. [ABSTRACT FROM AUTHOR]

Published
2024
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29. Si isotope homogeneity of the solar nebula

Author

Pringle, Emily A., Savage, Paul S., Jackson, Matthew G., Barrat, Jean-Alix, and Moynier, Frederic

Subjects
Astrophysics - Earth and Planetary Astrophysics
Abstract

The presence or absence of variations in the mass-independent abundances of Si isotopes in bulk meteorites provides important clues concerning the evolution of the early solar system. No Si isotopic anomalies have been found within the level of analytical precision of 15 ppm in 29Si/28Si across a wide range of inner solar system materials, including terrestrial basalts, chondrites, and achondrites. A possible exception is the angrites, which may exhibit small excesses of 29Si. However, the general absence of anomalies suggests that primitive meteorites and differentiated planetesimals formed in a reservoir that was isotopically homogenous with respect to Si. Furthermore, the lack of resolvable anomalies in the Calcium-Aluminum-rich Inclusion measured here suggests that any nucleosynthetic anomalies in Si isotopes were erased through mixing in the solar nebula prior to the formation of refractory solids. The homogeneity exhibited by Si isotopes may have implications for the distribution of Mg isotopes in the solar nebula. Based on supernova nucleosynthetic yield calculations, the expected magnitude of heavy-isotope overabundance is larger for Si than for Mg, suggesting that any potential Mg heterogeneity, if present, exists below the 15 ppm level.

Published
2013
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32. The Renchen L5-6 chondrite breccia – The first confirmed meteorite fall from Baden-Württemberg (Germany)

Author

Bischoff, Addi, Barrat, Jean-Alix, Berndt, Jasper, Borovicka, Jiri, Burkhardt, Christoph, Busemann, Henner, Hakenmüller, Janina, Heinlein, Dieter, Hertzog, Jasmine, Kaiser, Jozef, Maden, Colin, Meier, Matthias M.M., Morino, Précillia, Pack, Andreas, Patzek, Markus, Reitze, Maximilian P., Rüfenacht, Miriam, Schmitt-Kopplin, Philippe, Schönbächler, Maria, Spurný, Pavel, Weber, Iris, Wimmer, Karl, and Zikmund, Tomas

Published
2019
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35. Achondrites

Author

Yamaguchi, Akira, Barrat, Jean-Alix, Greenwood, Richard, White, William M., editor, Casey, William H., Associate Editor, Marty, Bernhard, Associate Editor, and Yurimoto, Hisayoshi, Associate Editor

Published
2018
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38. The Braunschweig meteorite − a recent L6 chondrite fall in Germany

Author

Bartoschewitz, Rainer, Appel, Peter, Barrat, Jean-Alix, Bischoff, Addi, Caffee, Marc W., Franchi, Ian A., Gabelica, Zelimir, Greenwood, Richard C., Harir, Mourad, Harries, Dennis, Hochleitner, Rupert, Hopp, Jens, Laubenstein, Matthias, Mader, Barbara, Marques, Rosa, Morlok, Andreas, Nolze, Gert, Prudêncio, Maria Isabel, Rochette, Pierre, Ruf, Alexander, Schmitt-Kopplin, Philippe, Seemann, Erhard, Szurgot, Marian, Tagle, Roald, Wach, Radosław A., Welten, Kees C., Weyrauch, Mona, and Wimmer, Karl

Published
2017
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43. The Behavior of Rare Earth Elements during Green Clay Authigenesis on the Congo Continental Shelf

Author

Bayon, Germain, Giresse, Pierre, Chen, Hongjin, Rouget, Marie-laure, Gueguen, Bleuenn, Moizinho, Gabriel Ribeiro, Barrat, Jean-alix, Beaufort, Daniel, Bayon, Germain, Giresse, Pierre, Chen, Hongjin, Rouget, Marie-laure, Gueguen, Bleuenn, Moizinho, Gabriel Ribeiro, Barrat, Jean-alix, and Beaufort, Daniel

Abstract

Clay mineral authigenesis at continental margins plays an important role in global marine element cycles. However, despite being increasingly used as tracers for both modern and past oceanographic conditions, the behavior of the rare earth elements (REEs) and their isotopes during marine clay authigenesis still remains poorly known. In this study, we report on a detailed geochemical investigation of glauconite from the West African continental shelf, near the mouth of the Congo River. Elemental, neodymium, and hafnium isotope analyses were conducted on both acid leachate and separated clay-size fractions of glauconite pellets, in order to investigate the behavior of REE during the formation of authigenic clays. Our data indicate that kaolinite dissolution and subsequent Fe-bearing clay authigenesis act as a net source of REEs to seawater. We show that enhanced glauconitization, as inferred from increasing Fe and K contents, is accompanied by significant decoupling of the REE toward markedly LREE-enriched shale-normalized patterns in neoformed clay separates. Using both Nd and Hf isotopes and SEM observations, we rule out any seawater influence and argue that this shift primarily reflects the progressively overwhelming presence of insoluble nanocrystals of detrital LREE-rich phosphates, which are known to occur in close association with kaolinite in tropical soils. Due to their marked insolubility in surface environments, such nanocrystals can be preserved during kaolinite dissolution and subsequently incorporated into the aggregates of authigenic green clays forming the peloids. Most strikingly, we show that the combined influence of net REE loss (due to kaolinite dissolution) and decoupling (due to subsequent entrapment of inherited LREE-bearing accessory phases into neoformed clay minerals) is accompanied by preferential release of a dissolved REE fraction characterized by seawater-like distribution patterns. These findings reinforce the emerging view that clay mi

Published
2023
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44. Portuguese Irons Of The Late Bronze. A Geochemical View

Author

Jambon, Albert, Vilaça, Raquel, Catarino, Lidia, Barrat, Jean-alix, Jambon, Albert, Vilaça, Raquel, Catarino, Lidia, and Barrat, Jean-alix

Abstract

The discovery of iron objects in Portugal, dated from the end of the Bronze Age (12th-11th century BC) in the context of habitats, forces us to reconsider the question of their significance. We present the results of a geo-chemical approach by the comparative analysis of archaeological irons and Portuguese ores. The p-XRF anal-ysis of 15 artifacts from 4 different sites in Beira Interior (Monte do Trigo, Moreirinha and Monte do Frade) and Central (Baiões), indicates that the smelted iron probably derived from two distinct ores. The local typol-ogy and the association of the finds with bronze workshops requires a reexamination as to the question of their origin. The chemical characterization of the irons of Beira Interior, indicates that they are of primitive elaboration given their low quality, while that of Baiões already shows a metallurgical evolution which would be understandable if it were more recent. A comparison with other Bronze Age irons underscores their chem-ical specificity. Local iron rich ores cropping out near Salvador (Penamacor, Beira Interior), were sampled and analyzed by ICP-AES and ICP-MS and compared with various types of iron ores. The composition of Salvador ores compared to that of the Beira Interior artifacts implies a definite consanguinity. The importation of fin-ished objects, such as ingots with local forging must be excluded. The processing of the local ore and its forging by experienced metallurgists but novices in iron metallurgy, is a new and robust explanatory hypothesis in accordance with all the constraints already mentioned. This is the first time that Bronze Age irons can be related to a very likely ore source. The Mediterranean influences, marking the importation of a new and ex-tremely recent know-how, therefore correspond, at least in part, to exchanges from the east and perhaps even to the movement of people. This exotic contribution would be linked to the profound movements in the Med-iterranean context of the 12th centur

Published
2023
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45. Quid de notre empreinte iodée?

Author

Guermazi, Dorra, primary, Jomaah, Raphel, additional, Tripier, Raphael, additional, Barrat, Jean-Alix, additional, Ognard, Julien, additional, and Salem, Douraied Ben, additional

Published
2023
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