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1. 53Mn-53Cr systematics of sphalerite in enstatite chondrites

Author

Hopp, Jens, Storck, Julian-Christopher, Ludwig, Thomas, Mostefaoui, Smail, Altherr, Rainer, Ott, Ulrich, Meyer, Hans-Peter, and Trieloff, Mario

Subjects
530 Physics, 550 Earth sciences & geology
Abstract

We investigated the 53Mn-53Cr isotopic composition of a suite of enstatite chondrites by in situ analyses of various mineral phases with the Cameca IMS 1280-HR ion probe at Heidelberg, Germany, and a Cameca NanoSIMS at Paris, France. Only in sphalerite we found anomalies in 53Cr/52Cr-ratios correlating with 55Mn/52Cr which are due to decay of short-lived 53Mn (t1/2 = 3.7 Ma). A sphalerite in the EH-impact melt LAP 02225 showed the largest excess of 53Cr, with 53Cr/52Cr-ratios ranging up to 2.2. The calculated initial 53Mn/55Mn-ratios are within the range of previous Mn-Cr studies. We observed a spatial variation within a large sphalerite in LAP 02225, translating in distinct initial 53Mn/55Mn values. In case of the EL3 chondrite MAC 88136 the initial 53Mn/55Mn derived for one sphalerite is at the lower end of previously reported values and may reflect a variable influence of alteration-induced exchange of common Cr. This is supported by the total reset of the 53Cr/52Cr-ratio in another sphalerite in contact with an alteration vein irrespective of high Mn/Cr-ratios. Our observed initial 53Mn/55Mn-ratios of Sahara 97158, Indarch and EET 96135 correspond to the I-Xe systematics and hence, show that sphalerites can preserve reasonable age information. For Indarch however, if compared with other initial 53Mn/55Mn values from literature, a considerable scatter is obvious. This clearly demonstrates that the Mn-Cr system in sphalerite can be disturbed by various, still poorly investigated, processes (e.g., by thermal events, weathering, diffusion-controlled remobilization). Future application of Mn-Cr dating to sphalerite in enstatite chondrites thus requires a better understanding of how such processes influence the Mn-Cr systematics and demands for tools to identify the undoubtly present sphalerites carrying a true chronologic information.

Published
2021
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2. Structure, composition, and location of organic matter in the enstatite chondrite Sahara 97096 (EH3)

Author

Piani, Laurette, Robert, FrançOis, Beyssac, Olivier, Binet, Laurent, Bourot-Denise, Michèle, Derenne, Sylvie, Guillou, Corentin Le, Marrocchi, Yves, Mostefaoui, Smail, Rouzaud, Jean-Noel, Thomen, Aurelien, Laboratoire de Minéralogie et Cosmochimie du Museum (LMCM), Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC), Laboratoire de Chimie de la Matière Condensée de Paris (LCMCP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Collège de France (CdF)-Centre National de la Recherche Scientifique (CNRS), Biogéochimie et écologie des milieux continentaux (Bioemco), Centre National de la Recherche Scientifique (CNRS)-AgroParisTech-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Recherche Agronomique (INRA)-École normale supérieure - Paris (ENS Paris), Laboratoire de géologie de l'ENS (LGE), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), Centre de Recherches Pétrographiques et Géochimiques (CRPG), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Minéralogie et Cosmochimie du Muséum (LMCM), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Collège de France (CdF (institution))-Institut de Chimie du CNRS (INC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Laboratoire de géologie de l'ENS (LGENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Collège de France (CdF (institution))-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL)

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), [SDU]Sciences of the Universe [physics], FOS: Physical sciences, Astrophysics - Earth and Planetary Astrophysics
Abstract

The insoluble organic matter (IOM) of an unequilibrated enstatite chondrite Sahara (SAH) 97096 has been investigated using a battery of analytical techniques. As the enstatite chondrites are thought to have formed in a reduced environment at higher temperatures than carbonaceous chondrites, they constitute an interesting comparative material to test the heterogeneities of the IOM in the solar system and to constrain the processes that could affect IOM during solar system evolution. The SAH 97096 IOM is found in situ: as submicrometer grains in the network of fine-grained matrix occurring mostly around chondrules and as inclusions in metallic nodules, where the carbonaceous matter appears to be more graphitized. IOM in these two settings has very similar $\delta^{15}N$ and $\delta^{13}C$; this supports the idea that graphitized inclusions in metal could be formed by metal catalytic graphitization of matrix IOM. A detailed comparison between the IOM extracted from a fresh part and a terrestrially weathered part of SAH 97096 shows the similarity between both IOM samples in spite of the high degree of mineral alteration in the latter. The isolated IOM exhibits a heterogeneous polyaromatic macromolecular structure, sometimes highly graphitized, without any detectable free radicals and deuterium-heterogeneity and having mean H- and N-isotopic compositions in the range of values observed for carbonaceous chondrites. It contains some submicrometer-sized areas highly enriched in $^{15}N$ ($\delta^{15}N$ up to 1600 permil). These observations reinforce the idea that the IOM found in carbonaceous chondrites is a common component widespread in the solar system. Most of the features of SAH 97096 IOM could be explained by the thermal modification of this main component.

Published
2015
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3. Report - Mineralogy and petrology of comet 81P/Wild 2 nucleus samples

Author

Zolensky, Michael E., Zega, Thomas J., Yano, Hajime, Wirick, Sue, Westphal, Andrew J., Weisberg, Mike K., Weber, Iris, Warren, Jack L., Velbel, Michael A., Tsuchiyama, Akira, Tsou, Peter, Toppani, Alice, Tomioka, Naotaka, Tomeoka, Kazushige, Teslich, Nick, Taheri, Mitra, Susini, Jean, Stroud, Rhonda, Stephan, Thomas, Stadermann, Frank J., Snead, Christopher J., Simon, Steven B., Simionovici, Alexandre, See, Thomas H., Robert, Francois, Rietmeijer, Frans J. M., Rao, William, Perronnet, Murielle C., Papanastassiou, Dimitri A., Okudaira, Kyoko, Ohsumi, Kazumasa, Ohnishi, Ichiro, Nakamura-Messenger, Keiko, Nakamura, Tomoki, Mostefaoui, Smail, Mikouchi, Takashi, Meibom, Anders, Matrajt, Graciela, Marcus, Matthew A., Leroux, Hugues, Lemelle, Laurence, Le, Loan, Lanzirotti, Antonio, Langenhorst, Falko, Krot, Alexander N., Keller, Lindsay P., Kearsley, Anton T., Joswiak, David, Jacob, Damien, Ishii, Hope, Harvey, Ralph, Hagiya, Kenji, Grossman, Lawrence, Grossman, Jeffrey N., Graham, Giles A., Gounelle, Matthieu, Gillet, Philippe, Genge, Matthew J., Flynn, George, Ferroir, Tristan, Fallon, Stewart, Ebel, Denton S., Dai, Zu Rong, Cordier, Patrick, Clark, Benton, Chi, Miaofang, Butterworth, Anna L., Brownlee, Donald E., Bridges, John C., Brennan, Sean, Brearley, Adrian, Bradley, John P., Bleuet, Pierre, Bland, Phil A., and Bastien, Ron

Subjects
Grains, Origin, Matrix, Olivine, Carbonaceous Chondrite, Solar-System, Halley, Components, Pyroxene, Interplanetary Dust Particles
Abstract

The bulk of the comet 81P/Wild 2 ( hereafter Wild 2) samples returned to Earth by the Stardust spacecraft appear to be weakly constructed mixtures of nanometer-scale grains, with occasional much larger ( over 1 micrometer) ferromagnesian silicates, Fe-Ni sulfides, Fe-Ni metal, and accessory phases. The very wide range of olivine and low-Ca pyroxene compositions in comet Wild 2 requires a wide range of formation conditions, probably reflecting very different formation locations in the protoplanetary disk. The restricted compositional ranges of Fe-Ni sulfides, the wide range for silicates, and the absence of hydrous phases indicate that comet Wild 2 experienced little or no aqueous alteration. Less abundant Wild 2 materials include a refractory particle, whose presence appears to require radial transport in the early protoplanetary disk.

4. Implications of in situ calcification for photosynthesis in a similar to 3.3 Ga-old microbial biofilm from the Barberton greenstone belt, South Africa

Author

Westall, Frances, Cavalazzi, Barbara, Lemelle, Laurence, Marrocchi, Yves, Rouzaud, Jean-Noel, Simionovici, Alexandre, Salome, Murielle, Mostefaoui, Smail, Andreazza, Caroline, Foucher, Frederic, Toporski, Jan, Jauss, Andrea, Thiel, Volker, Southam, Gordon, MacLean, Lachlan, Wirick, Susan, Hofmann, Axel, Meibom, Anders, Robert, Francois, and Defarge, Christian

Subjects
Onverwacht Group, Western-Australia, photosynthesis, Sedimentary-Rocks, Early Earth, Sulfate-Reducing Bacteria, microbial mat, aragonite, Preservation, calcification, Stromatolites, Mountain Land, Early-Life, Barberton, Sulfur
Abstract

Timing the appearance of photosynthetic microorganisms is crucial to understanding the evolution of life on Earth. The ability of the biosphere to use sunlight as a source of energy (photoautotrophy) would have been essential for increasing biomass and for increasing the biogeochemical capacity of all prokaryotes across the range of redox reactions that support life. Typical proxies for photosynthesis in the rock record include features, such as a mat-like, laminated morphology (stratiform, domical, conical) often associated with bulk geochemical signatures, such as calcification, and a fractionated carbon isotope signature. However, to date, in situ, calcification related to photosynthesis has not been demonstrated in the oldest known microbial mats. We here use in situ nanometre-scale techniques to investigate the structural and compositional architecture in a 3.3 billion-year (Ga) old microbial biofilm from the Barberton greenstone belt, thus documenting in situ calcification that was most likely related to anoxygenic photosynthesis. The Josefsdal Chert Microbial Biofilm (JCMB) formed in a littoral (photic) environment It is characterised by a distinct vertical structural and compositional organisation. The lower part is calcified in situ by aragonite, progressing upwards into uncalcified kerogen characterised by up to 1% sulphur, followed by an upper layer that contains intact filaments at the surface. Crystallites of pseudomorphed pyrite are also associated with the biofilm suggesting calcification related to the activity of heterotrophic sulphur reducing bacteria. In this anoxygenic, nutrient-limited environment, the carbon required by the sulphur reducing bacteria could only have been produced by photoautotrophy. We conclude that the Josfsdal Chen Microbial Biofilm was formed by a consortium of anoxygenic microorganisms, including photosynthesisers and sulphur reducing bacteria. (C) 2011 Elsevier B.V. All rights reserved.

5. Research article - Comet 81P/Wild 2 under a microscope

Author

Brownlee, Don, Tsou, Peter, Aleon, Jerome, Alexander, Conel M. O'D., Araki, Tohru, Bajt, Sasa, Baratta, Giuseppe A., Bastien, Ron, Bland, Phil, Bleuet, Pierre, Borg, Janet, Bradley, John P., Brearley, Adrian, Brenker, F., Brennan, Sean, Bridges, John C., Browning, Nigel D., Brucato, John R., Bullock, E., Burchell, Mark J., Busemann, Henner, Butterworth, Anna, Chaussidon, Marc, Cheuvront, Allan, Chi, Miaofang, Cintala, Mark J., Clark, B. C., Clemett, Simon J., Cody, George, Colangeli, Luigi, Cooper, George, Cordier, Patrick, Daghlian, C., Dai, Zurong, D'Hendecourt, Louis, Djouadi, Zahia, Dominguez, Gerardo, Duxbury, Tom, Dworkin, Jason P., Ebel, Denton S., Economou, Thanasis E., Fakra, Sirine, Fairey, Sam A. J., Fallon, Stewart, Ferrini, Gianluca, Ferroir, T., Fleckenstein, Holger, Floss, Christine, Flynn, George, Franchi, Ian A., Fries, Marc, Gainsforth, Z., Gallien, J. -P., Genge, Matt, Gilles, Mary K., Gillet, Philipe, Gilmour, Jamie, Glavin, Daniel P., Gounelle, Matthieu, Grady, Monica M., Graham, Giles A., Grant, P. G., Green, Simon F., Grossemy, Faustine, Grossman, Lawrence, Grossman, Jeffrey N., Guan, Yunbin, Hagiya, Kenji, Harvey, Ralph, Heck, Philipp, Herzog, Gregory F., Hoppe, Peter, Hoerz, Friedrich, Huth, Joachim, Hutcheon, Ian D., Ignatyev, Konstantin, Ishii, Hope, Ito, Motoo, Jacob, Damien, Jacobsen, Chris, Jacobsen, Stein, Jones, Steven, Joswiak, David, Jurewicz, Amy, Kearsley, Anton T., Keller, Lindsay P., Khodja, H., Kilcoyne, A. L. David, Kissel, Jochen, Krot, Alexander, Langenhorst, Falko, Lanzirotti, Antonio, Le, Loan, Leshin, Laurie A., Leitner, J., Lemelle, L., Leroux, Hugues, Liu, Ming-Chang, Luening, K., Lyon, Ian, MacPherson, Glen, Marcus, Matthew A., Marhas, Kuljeet, Marty, Bernard, Matrajt, Graciela, McKeegan, Kevin, Meibom, Anders, Mennella, Vito, Messenger, Keiko, Messenger, Scott, Mikouchi, Takashi, Mostefaoui, Smail, Nakamura, Tomoki, Nakano, T., Newville, M., Nittler, Larry R., Ohnishi, Ichiro, Ohsumi, Kazumasa, Okudaira, Kyoko, Papanastassiou, Dimitri A., Palma, Russ, Palumbo, Maria E., Pepin, Robert O., Perkins, David, Perronnet, Murielle, Pianetta, P., Rao, William, Rietmeijer, Frans J. M., Robert, Francois, Rost, D., Rotundi, Alessandra, Ryan, Robert, Sandford, Scott A., Schwandt, Craig S., See, Thomas H., Schlutter, Dennis, Sheffield-Parker, J., Simionovici, Alexandre, Simon, Steven, Sitnitsky, I., Snead, Christopher J., Spencer, Maegan K., Stadermann, Frank J., Steele, Andrew, Stephan, Thomas, Stroud, Rhonda, Susini, Jean, Sutton, S. R., Suzuki, Y., Taheri, Mitra, Taylor, Susan, Teslich, Nick, Tomeoka, Kazu, Tomioka, Naotaka, Toppani, Alice, Trigo-Rodriguez, Josep M., Troadec, David, Tsuchiyama, Akira, Tuzzolino, Anthony J., Tyliszczak, Tolek, Uesugi, K., Velbel, Michael, Vellenga, Joe, Vicenzi, E., Vincze, L., Warren, Jack, Weber, Iris, Weisberg, Mike, Westphal, Andrew J., Wirick, Sue, Wooden, Diane, Wopenka, Brigitte, Wozniakiewicz, Penelope, Wright, Ian, Yabuta, Hikaru, Yano, Hajime, Young, Edward D., Zare, Richard N., Zega, Thomas, Ziegler, Karen, Zimmerman, Laurent, Zinner, Ernst, and Zolensky, Michael

Subjects
Grains, Origin, Solar Nebula, Physics::Space Physics, Crystalline Silicates, P/Wild 2, Astrophysics::Solar and Stellar Astrophysics, Kuiper Belt, Astrophysics::Earth and Planetary Astrophysics, Mineralogy, Refractory Inclusions, Nucleus
Abstract

The Stardust spacecraft collected thousands of particles from comet 81P/Wild 2 and returned them to Earth for laboratory study. The preliminary examination of these samples shows that the nonvolatile portion of the comet is an unequilibrated assortment of materials that have both presolar and solar system origin. The comet contains an abundance of silicate grains that are much larger than predictions of interstellar grain models, and many of these are high-temperature minerals that appear to have formed in the inner regions of the solar nebula. Their presence in a comet proves that the formation of the solar system included mixing on the grandest scales.

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