Science.gov

Sample records for chondrite matter originally

  1. The origin of chondritic macromolecular organic matter: a carbon and nitrogen isotope study.

    PubMed

    Alexander, C M; Russell, S S; Arden, J W; Ash, R D; Grady, M M; Pillinger, C T

    1998-07-01

    The N and C abundances and isotopic compositions of acid-insoluble carbonaceous material in thirteen primitive chondrites (five unequilibrated ordinary chondrites, three CM chondrites, three enstatite chondrites, a CI chondrite and a CR chondrite) have been measured by stepped combustion. While the range of C isotopic compositions observed is only delta 13C = 30%, the N isotopes range from delta 15N approximately -40 to 260%. After correction for metamorphism, presolar nanodiamonds appear to have made up a fairly constant 3-4 wt% of the insoluble C in all the chondrites studied. The apparently similar initial presolar nanodiamond to organic C ratios, and the correlations of elemental and isotopic compositions with metamorphic indicators in the ordinary and enstatite chondrites, suggest that the chondrites all accreted similar organic material. This original material probably most closely resembles that now found in Renazzo and Semarkona. These two meteorites have almost M-shaped N isotope release profiles that can be explained most simply by the super-position of two components, one with a composition between delta 15N = -20 and -40% and a narrow combustion interval, the other having a broader release profile and a composition of delta 15N approximately 260%. Although isotopically more subdued, the CI and the three CM chondrites all appear to show vestiges of this M-shaped profile. How and where the components in the acid-insoluble organics formed remains poorly constrained. The small variation in nanodiamond to organic C ratio between the chondrite groups limits the local synthesis of organic matter in the various chondrite formation regions to at most 30%. The most 15N-rich material probably formed in the interstellar medium, and the fraction of organic N in Renazzo in this material ranges from 40 to 70%. The isotopically light component may have formed in the solar system, but the limited range in nanodiamond to total organic C ratios in the chondrite groups is

  2. Origin of insoluble organic matter in type 1 and 2 chondrites: New clues, new questions

    NASA Astrophysics Data System (ADS)

    Quirico, Eric; Orthous-Daunay, François-Régis; Beck, Pierre; Bonal, Lydie; Brunetto, Rosario; Dartois, Emmanuel; Pino, Thomas; Montagnac, Gilles; Rouzaud, Jean-Noël; Engrand, Cécile; Duprat, Jean

    2014-07-01

    Insoluble organic matter (IOM) extracted from primitive chondrites is a polyaromatic solid with a structure and composition resembling that of terrestrial kerogens. A survey of its composition and structure has been carried out on a series of 27 CR, CM, CI and ungrouped C2 carbonaceous chondrites (Tagish Lake, Bells, Essebi, Acfer 094) using infrared and multi-wavelength Raman micro-spectroscopy (244, 514 and 785 nm laser excitations). The results show that chondritic IOM from PCA 91008 (CM2), WIS 91600 (CM2), QUE 93005 (CM2), Tagish Lake (C2 ungrouped) and possibly Cold Bokkeveld (CM2) has been subjected to the past action of short duration thermal metamorphism, presumably triggered by impacts. The IOM in most of the CM chondrites that experienced moderate to heavy aqueous alteration may have been slightly modified by collision-induced heating. However, even IOM from chondrites that escaped significant thermal metamorphism displays Raman characteristics consistent with a formation by thermal processing, either in the protosolar disk or in the parent body. An alternative energetic process to thermal heating is ion irradiation. After thoroughly analyzing both these scenarii, no conclusion can be drawn as to which is the most plausible mechanism nor whether the heating process took place prior or after accretion. The results show for the first time that the width of the G band in spectra collected with a 514 nm excitation correlates with the O/C atomic ratio, suggesting a major role of oxygen in the cross-linking of polyaromatic units.

  3. Igneous rock from Severnyi Kolchim (H3) chondrite: Nebular origin

    NASA Technical Reports Server (NTRS)

    Nazarov, M. A.; Brandstaetter, F.; Kurat, G.

    1993-01-01

    The discovery of lithic fragments with compositions and textures similar to igneous differentiates in unequilibrated ordinary chondrites (UOC's) and carbonaceous chondrites (CC's) has been interpreted as to suggest that planetary bodies existed before chondrites were formed. As a consequence, chondrites (except, perhaps CI chondrites) cannot be considered primitive assemblages of unprocessed nebular matter. We report about our study of an igneous clast from the Severnyi Kolchim (H3) chondrite. The results of the study are incompatible with an igneous origin of the clast but are in favor of a nebular origin similar to that of chondrules.

  4. Origin and evolution of ordinary chondrite meteorites

    NASA Technical Reports Server (NTRS)

    Scott, E. R. D.; Taylor, G. J.; Keil, K.

    1985-01-01

    The effects of heating on the chemical composition, minerology, and texture of chondrite meteorites are discussed chondrite origin and evolution. Various asteroidal and nebular heating mechanisms are considered to account meteorite compositions.

  5. Origin of organic matter in the early solar system. VII - The organic polymer in carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Hayatsu, R.; Matsuoka, S.; Anders, E.; Scott, R. G.; Studier, M. H.

    1977-01-01

    Degradation techniques, including pyrolysis, depolymerization, and oxidation, were used to study the insoluble polymer from the Murchison C2 chondrite. Oxidation with Cr2O7(2-) or O2/UV led to the identification of 15 aromatic ring systems. Of 11 aliphatic acids identified, three dicarboxylic acids presumably came from hydroaromatic portions of the polymer, whereas eight monocarboxylic acids probably derive from bridging groups or ring substituents. Depolymerization with CF3COO4 yielded some of the same ring systems, as well as alkanes (C1 through C8) and alkenes (C2 through C8), alkyl (C1 through C5) benzenes and naphthalenes, and methyl- or dimethyl -indene, -indane, -phenol, -pyrrole, and -pyridine. All these compounds were detected below 200 C, and are therefore probably indigenous constituents. The properties of the meteoritic polymer were compared with the properties of a synthetic polymer produced by the Fischer-Tropsch reaction. It is suggested that the meteoritic polymer was also produced by surface catalysis.

  6. Origin of organic matter in the early solar system. VII - The organic polymer in carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Hayatsu, R.; Matsuoka, S.; Anders, E.; Scott, R. G.; Studier, M. H.

    1977-01-01

    Degradation techniques, including pyrolysis, depolymerization, and oxidation, were used to study the insoluble polymer from the Murchison C2 chondrite. Oxidation with Cr2O7(2-) or O2/UV led to the identification of 15 aromatic ring systems. Of 11 aliphatic acids identified, three dicarboxylic acids presumably came from hydroaromatic portions of the polymer, whereas eight monocarboxylic acids probably derive from bridging groups or ring substituents. Depolymerization with CF3COO4 yielded some of the same ring systems, as well as alkanes (C1 through C8) and alkenes (C2 through C8), alkyl (C1 through C5) benzenes and naphthalenes, and methyl- or dimethyl -indene, -indane, -phenol, -pyrrole, and -pyridine. All these compounds were detected below 200 C, and are therefore probably indigenous constituents. The properties of the meteoritic polymer were compared with the properties of a synthetic polymer produced by the Fischer-Tropsch reaction. It is suggested that the meteoritic polymer was also produced by surface catalysis.

  7. Carbonaceous chondrites and the origin of life

    NASA Technical Reports Server (NTRS)

    Hartman, Hyman; Sweeney, Michael A.; Kropp, Michael A.; Lewis, John S.

    1993-01-01

    Organic matter in carbonaceous chondrites can be separated into three fractions. The first component, the fraction that is insoluble in chloroform and methanol, has a part which is of interstellar origin. The other two fractions (chloroform-soluble hydrocarbons and methanol-soluble polar organics) are hypothesized to have been synthesized on a planetoid body. We propose that the polar organics, i.e., amino acids, were synthesized close to its surface by the radiolysis of hydrocarbons and ammonium carbonate in a liquid water environment. Some hydrocarbons may have been synthesized by a Fischer-Tropsch mechanism in the interior of the body. Ferrous ion acted as a protection against back reactions. The simultaneous synthesis of iron-rich clays with the polar organics may be indicative of events related to the origin of life on Earth.

  8. Origin of organic compounds in carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Cronin, J. R.

    Carbonaceous chondrites, a class of primitive meteorite, have long been known to contain their complement of carbon largely in the form of organic, i.e., hydrocarbon-related, matter. Both discrete organic compounds and an insoluble, macromolecular material are present. Several characteristics of these materials provide evidence for their abiotic origin. The principal formation hypothesis have invoked chemistry occurring either in the solar nebula or on the parent body. However, recent stable isotope analyses of the meteorite carboxylic acids and amino acids indicate that they may be related to interstellar cloud compounds. These results suggest a formation scheme in which interstellar compounds were incorporated into the parent body and subsequently converted to the present suite of meteorite organics by the hydrothermal process believed to have formed the clay minerals of the meteorite matrix.

  9. CARBONACEOUS MATTER PRECURSORS AND METAMORPHIC CONDITIONS IN THERMALLY PROCESSED CHONDRITES

    NASA Astrophysics Data System (ADS)

    Quirico, E.; Montagnac, G.; Rouzaud, J.; Bonal, L.; Bourot-Denise, M.; Duber, S.; Reynard, B.

    2009-12-01

    Unravelling the origin of carbonaceous matter in pristine chondrites requires the understanding of the effect of post-accretion processes. In chondrites of petrologic type 3, thermal metamorphism modified to various extents the composition and structure of carbonaceous matter. Interestingly, this process controls the degree of structural order of carbonaceous matter, and clues on the thermal history of the parent body may be recovered from the physico-chemical study of carbonaceous matter. Following this framework, geothermometers based on Raman spectrometry of carbonaceous matter and covering a wide range of temperatures (100-650 °C) have been developed over recent years, both on terrestrial rocks and chondrites. While Raman data have been largely interpreted in terms of temperature, they are also the fingerprint of certain metamorphic conditions, especially in the low temperature range relevant to poorly ordered carbonaceous matter. This study investigates the Raman spectra of two series of chondritic carbonaceous matter and coal samples formed from different precursors and under different metamorphic conditions. The Raman spectra of Polyaromatic Carbonaceous Matter (PCM) from 42 chondrites and 27 coal samples, measured with visible (514 nm) and ultra-violet (244 nm) excitation wavelengths, are analyzed. The Raman spectra of low rank coals and chondrites of petrologic types 1 and 2, which contain the more disordered PCM, reflect the distinct carbon structures of their precursors. The 514 nm Raman spectra of high rank coals and chondrites of petrologic type 3 exhibit continuous and systematic spectral differences reflecting different carbon structures present during the metamorphism event. They result from differences in the chemical structures of the precursors concerning for instance the reticulation of polyaromatic units or an abundance of ether functional groups, or possibly from a lack of carbonization processes to efficiently expel oxygen heteroatoms, due

  10. Solar gases in meteorites - The origin of chondrites and C1 carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Heymann, D.

    1978-01-01

    Evidence suggesting that chondritic meteorites broke off from parent bodies in earth-crossing orbits is considered. It is suggested that ordinary chondrites have an asteroidal origin, and the possibility that C1 chondrites have a cometary origin is examined. Indications of heavy shock and reheating among L and H chondrites provides support for an asteroidal origin, while the Apollo and Amor objects are too small to be unfragmented asteroids, as proposed in the Anders theory of the origin of gas-rich meteorites. Events associated with the megaregolith are discussed in the framework of the proposed cometary origin of C1 chondrites.

  11. The Origin of Chondrules and Chondrites

    NASA Astrophysics Data System (ADS)

    Sears, Derek W. G.

    2005-01-01

    Drawing on research from the various scientific disciplines involved, this text summarizes the origin and history of chondrules and chondrites. Including citations to every published paper on the topic, it forms a comprehensive bibliography of the latest research. In addition, extensive illustrations provide a clear visual representation of the scientific theories. The text will be a valuable reference for graduate students and researchers in planetary science, geology and astronomy.

  12. Structural and Isotopic Analysis of Organic Matter in Carbonaceous Chondrites

    NASA Astrophysics Data System (ADS)

    Gilmour, I.

    2003-12-01

    The most ancient organic molecules available for study in the laboratory are those carried to Earth by infalling carbonaceous chondrite meteorites. All the classes of compounds normally considered to be of biological origin are represented in carbonaceous meteorites and, aside from some terrestrial contamination; it is safe to assume that these organic species were produced by nonbiological methods of synthesis. In effect, carbonaceous chondrites are a natural laboratory containing organic molecules that are the product of ancient chemical evolution. Understanding the sources of organic molecules in meteorites and the chemical processes that led to their formation has been the primary research goal. Circumstellar space, the solar nebulae, and asteroidal meteorite parent bodies have all been suggested as environments where organic matter may have been formed. Determination of the provenance of meteoritic organic matter requires detailed structural and isotopic information, and the fall of the Murchison CM2 chondrite in 1969 enabled the first systematic organic analyses to be performed on comparatively pristine samples of extraterrestrial organic material. Prior to that, extensive work had been undertaken on the organic matter in a range of meteorite samples galvanized, in part, by the controversial debate in the early 1960s on possible evidence for former life in the Orgueil carbonaceous chondrite (Fitch et al., 1962; Meinschein et al., 1963). It was eventually demonstrated that the suggested biogenic material was terrestrial contamination ( Fitch and Anders, 1963; Anders et al., 1964); however, the difficulties created by contamination have posed a continuing problem in the analysis and interpretation of organic material in meteorites (e.g., Watson et al., 2003); this has significant implications for the return of extraterrestrial samples by space missions. Hayes (1967) extensively reviewed data acquired prior to the availability of Murchison samples

  13. The Chondrite Types and Their Origins

    NASA Astrophysics Data System (ADS)

    Wood, J. A.

    2005-12-01

    Recent advances in the dating of ferromagnesian chondrules are summarized, and the conclusion seems unavoidable (the author's earlier convictions notwithstanding) that chondrules comprising a given chondrite are the product of nebular activity extending over a million years or more. Continuing chondrule-forming activity, probably successive shock events, can explain the non-solar major element chemical compositions of the ordinary chondrites (OC): they are the cumulative effect of repeated small changes in the local system composition that accompanied each chondrule- forming event. In particular Fe,Ni metal was increasingly lost from the system with time, presumably by incorporation in planetesimals (most of them unsampled) at the nebular midplane. Fe/Si in the system progressed smoothly with time through values appropriate to the H, L, and LL OC groups. The parent bodies of each of these groups were accreted in a relatively short time, during which Fe/Si was essentially constant, then accretion effectively ceased, probably because the parent body was perturbed into an inclined orbit and no longer spent much time in the chondrule-rich nebular midplane. The perturbations are probably ascribable to the same density waves (gravitational irregularities) that created chondrule-forming shocks. Implementation of this concept is also explored for carbonaceous and enstatite chondrites. Maintenance of the differences in composition of the various chondrite types, which formed at differing radial distances, requires that turbulent diffusion was not effective in the zone of chondrite formation. Instead periodic disturbances by the nebular density waves were probably responsible for remixing solids from the midplane zone into the body of the nebula.

  14. Compositions of three low-FeO ordinary chondrites: Indications of a common origin with the H chondrites

    SciTech Connect

    Troiano, Julianne; Rumble III, Douglas; Rivers, Mark L.; Friedrich, Jon M.

    2011-11-17

    Burnwell, EET 96031, and LAP 04575 are ordinary chondrites (OC) that possess lower than typical olivine Fa content than has been established for the H chondrites (< 17 mol%). Mean low-Ca pyroxene Fs contents are typically lower than mean Fa content, with generally 16 mol% Fs. We have investigated these three low-FeO chondrites by measuring their trace element abundances, oxygen isotopic compositions, and examining their three-dimensional (3D) petrography with synchrotron X-ray microtomography. We compare our results with those established for more common OC. The low FeO chondrites studied here have bulk trace element abundances that are identical to the H chondrites. From bulk oxygen isotopic analysis, we show that Burnwell, EET 96010, and LAP 04757 sampled oxygen reservoirs identical to the H chondrites. Burnwell, EET 96031, and LAP 04575 possess common 3D opaque mineral structures that could be distinct from the H chondrites, as evidenced by X-ray microtomographic analysis, but our comparison suite of H chondrites is small and unrepresentative. Overall, our data suggest a common origin for the low-FeO chondrites Burnwell, EET 96010, and LAP 04757 and the H chondrites. These three samples are simply extreme members of a redox process where a limiting nebular oxidizing agent, probably ice, reacted with material containing slightly higher amounts of metal than typically seen in the H chondrites.

  15. Origin and chronology of chondritic components: A review

    NASA Astrophysics Data System (ADS)

    Krot, A. N.; Amelin, Y.; Bland, P.; Ciesla, F. J.; Connelly, J.; Davis, A. M.; Huss, G. R.; Hutcheon, I. D.; Makide, K.; Nagashima, K.; Nyquist, L. E.; Russell, S. S.; Scott, E. R. D.; Thrane, K.; Yurimoto, H.; Yin, Q.-Z.

    2009-09-01

    Mineralogical observations, chemical and oxygen-isotope compositions, absolute 207Pb- 206Pb ages and short-lived isotope systematics ( 7Be- 7Li, 10Be- 10B, 26Al- 26Mg, 36Cl- 36S, 41Ca- 41K, 53Mn- 53Cr, 60Fe- 60Ni, 182Hf- 182W) of refractory inclusions [Ca,Al-rich inclusions (CAIs) and amoeboid olivine aggregates (AOAs)], chondrules and matrices from primitive (unmetamorphosed) chondrites are reviewed in an attempt to test (i) the x-wind model vs. the shock-wave model of the origin of chondritic components and (ii) irradiation vs. stellar origin of short-lived radionuclides. The data reviewed are consistent with an external, stellar origin for most short-lived radionuclides ( 7Be, 10Be, and 36Cl are important exceptions) and a shock-wave model for chondrule formation, and provide a sound basis for early Solar System chronology. They are inconsistent with the x-wind model for the origin of chondritic components and a local, irradiation origin of 26Al, 41Ca, and 53Mn. 10Be is heterogeneously distributed among CAIs, indicating its formation by local irradiation and precluding its use for the early solar system chronology. 41Ca- 41K, and 60Fe- 60Ni systematics are important for understanding the astrophysical setting of Solar System formation and origin of short-lived radionuclides, but so far have limited implications for the chronology of chondritic components. The chronological significance of oxygen-isotope compositions of chondritic components is limited. The following general picture of formation of chondritic components is inferred. CAIs and AOAs were the first solids formed in the solar nebula ˜4567-4568 Myr ago, possibly within a period of <0.1 Myr, when the Sun was an infalling (class 0) and evolved (class I) protostar. They formed during multiple transient heating events in nebular region(s) with high ambient temperature (at or above condensation temperature of forsterite), either throughout the inner protoplanetary disk (1-4 AU) or in a localized region

  16. Comments on D/H ratios in chondritic organic matter

    NASA Astrophysics Data System (ADS)

    Smith, J. W.; Rigby, D.

    1981-06-01

    D/H ratios in chondritic organic matter are investigated. Demineralized organic residues obtained from previous experiments were dried in a quartz reaction vessel under vacuum for 60 minutes at 250-300 C and then combusted in oxygen for 20 minutes at 850 C. The apparatus is described and the results of the experiments such as D/H ratios in water and measurements on total carbon dioxide are given. Atomic H/C ratios calculated directly from the quantities of carbon dioxide and water recovered, are reported according to Standard Mean Ocean Water and Pee Dee Belemnite, using the customary notation.

  17. Origin of volatile-rich H chondrites with light/dark structures

    NASA Technical Reports Server (NTRS)

    Mcsween, H. Y., Jr.; Lipschutz, M. E.

    1980-01-01

    The light and dark fractions of four gas-rich, brecciated H chondrites are studied in terms of petrography and volatile element chemistry in an investigation of the origin of light/dark chondrites. Petrographic constraints on the nature of the light and dark fractions of the meteorites are presented. Light clasts within the brecciated H chondrites are more highly metamorphosed than dark host material, and olivine, pyroxene and metal compositions suggest that dark fractions consist of mixtures of unequilibrated material and pulverized equilibrated H chondrite similar to the light clasts. Volatile element concentrations in the dark fractions are similar to those in the least equilibrated H3 chondrites, and no petrographic evidence for admixture of significant amounts of carbonaceous chondrite was noted. It is concluded that volatile-rich H chondrite breccias may not have incorporated carbonaceous chondrite dust as the volatile element carrier.

  18. Origin of Nanodiamonds in Primitive Chondrites: (1) Theory

    NASA Astrophysics Data System (ADS)

    Ozima, M.; Mochizuki, K.

    1993-07-01

    Microdiamonds in primitive chondrites are characterized by Xe-HL, which supposedly formed in a type II supernova. Several models have been proposed for the origin of the microdiamonds. These include chemical vapor deposition (CVD) [e.g., 1], interstellar shock [2], and UV-annealing of small graphite particles [3]. However, it is difficult for any of these models to explain the unique association of Xe-HL with the microdiamonds. We have suggested that a diamond formation process, proposed by Kaminsky [4], for the origin of a particular terrestrial diamond, carbonado, may apply to the microdiamonds in primitive meteorites [5,6]: Kaminsky speculated that carbonado was formed from natural coal that was enriched in uranium and hence subjected to irradiation by high-energy particles produced from the uranium and thorium. The paper in this volume by Mochizuki et al. [7] reports nanometer-sized diamondlike clusters in a uranium-rich natural coal, in accordance with Kaminsky's hypothesis. Mochizuki et al. also report the possibility of the production of nanodiamonds in graphite that was irradiated with a 50-KeV argon beam. These experimental studies strongly suggest that microdiamonds can be produced by irradiation of carbonaceous matters with energetic particles. On the basis of these experimental results, we propose a scenario for the origin of the microdiamonds in primitive chondrites. The scenario gives a reasonable explanation for the unique association of Xe-HL with the microdiamonds as well as for their formation in a supernova envelope. We assume that carbonaceous materials (amorphous carbon, graphite, and hydrocarbon grains) in the outer envelope of a supernova was irradiated by energetic particles (including Xe-HL) emitted during supernova explosion. The energetic particles then interacted with the carbonaceous matter: Most of the energy was dissipated through electronic interaction, and at the end of the journey the particles produced cascade displacement of

  19. Morphological study of Insoluble Organic Matter from carbonaceous chondrites: Correlation with petrologic grade

    NASA Astrophysics Data System (ADS)

    Changela, Hitesh G.

    2015-06-01

    The major form of organic material delivered to Earth from an extraterrestrial origin is Insoluble Organic Matter (IOM). A morphological study of IOM in the CR (Renazzo-type) and CM (Mighei-type) carbonaceous chondrites was performed in order to constrain its origins and processing history. IOM residues from the following CR chondrites: GRO 95577 (CR1), Al Rais (CR1/2), EET 92042 (CR2), QUE 99177 (CR3) and the CM chondrites: MET 01070 (CM2.2), Cold Bokkeveld (CM2.3), Murchison (CM2.4) and QUE 97990 (CM2.5) were studied using Annular Dark Field STEM imaging. Characteristic features of the IOM, organic nanoglobules, were manually identified and measured for their abundances and size distributions. The IOM residues were also compared holistically for their degree of average 'roughness' or 'coarsening' using fractal image analysis. Manually identified nanoglobules have abundances making up less than 10% of the total IOM, which is consistent with previous studies. Their measured abundances do not correlate with petrologic grade. Thus parent body processing did not systematically deplete their abundances. The IOM is however on average 'smoother' or 'coarser' in the more altered chondrites, demonstrated by a lower fractal dimension using fractal box counting (DB). The DB values for the IOM in the CR chondrites are distinctive: QUE 99177 has the largest DB value (average = 1.54 ± 0.004) and GRO 99577 has the lowest (average = 1.45 ± 0.011). Al Rais and EET 92042 have IOM with average DB values within this range (average, 1.46 ± 0.009 and 1.50 ± 0.006). The CMs record a similar but less distinctive trend in DB, with QUE 97990 having the largest value (1.52 ± 0.004), MET 01070 the lowest (1.45 ± 0.019), and Cold Bokkeveld (1.50 ± 0.011) and Murchison (1.49 ± 0.017) equivalent to one another within error. The identified nanoglobules in the IOM of the CM chondrites are on average larger than those in the CR chondrites. The 'coarsening' or 'smoother' texture of the IOM

  20. HRTEM and EFTEM Observations of Matrix in the Oxidized CV3 Chondrite ALH 84028: Implications for the Origins of Matrix Olivines

    NASA Technical Reports Server (NTRS)

    Abreu, Neyda M.; Brearley, Adrian J.

    2003-01-01

    The determination of the nature, distribution, and origin of organic material in carbonaceous chondrites is fundamental to understanding early solar nebular conditions and the origin of life. Using a variety of extraction techniques, followed by detailed chemical analysis, an extensive suite of organic compounds has been identified in carbonaceous chondrites. These data have provided key information on the diversity and isotopic composition of the organic component in chondrites. However, one disadvantage of extraction techniques is that all information regarding the spatial distribution of the organics on a fine scale is lost. This is especially important for the insoluble macromolecular carbon, which constitutes approximately 70% of the carbon in carbonaceous chondrites such as Murchison. The distribution and mineralogical associations may provide important constraints on the possible origins of the carbonaceous material. Our previous studies of the CV3 chondrites Allende and Vigarano have demonstrated that energy filtered transmission electron microscopy (EFTEM), combined with high resolution TEM (HRTEM) are powerful tools for the in situ characterization of insoluble organic matter in carbonaceous chondrites. In this study, we have used SEM and TEM techniques to characterize the matrix mineralogy of the CV3 chondrite ALH 84028 and examine the distribution and mineralogical associations of carbon. We are especially interested in establishing whether the occurrence of poorly graphitized carbon (PGC), observed in Allende matrix olivines, is common to all oxidized CV3 chondrites or is a unique feature of Allende.

  1. Chemical characteristics and origin of H chondrite regolith breccias

    NASA Technical Reports Server (NTRS)

    Lipschutz, M. E.; Biswas, S.; Mcsween, H. Y., Jr.

    1983-01-01

    Petrologic data and contents of Ag, Bi, Cd, Co, Cs, Ga, In, Rb, Se, Te, Tl and Zn-trace elements spanning the volatility/mobility range-in light and dark portions of H chondrite regolith breccias and L chondrite fragmental breccias are reported. The chemical/petrologic characteristics of H chondrite regolith breccias differ from those of nonbrecciated chondrites or fragmental breccias. Petrologic characteristics and at least some trace element contents of H chondrite regolith breccias reflect primary processes; contents of the most volatile/mobile elements may reflect either primary or secondary processing, possibly within layered H chondrite parent object(s). Chemical/petrologic differences existed in different regions of the parent(s). Regoligh formation and gardening and meteoroid compaction were not so severe as to alter compositions markedly.

  2. Chemical characteristics and origin of H chondrite regolith breccias

    NASA Technical Reports Server (NTRS)

    Lipschutz, M. E.; Biswas, S.; Mcsween, H. Y., Jr.

    1983-01-01

    Petrologic data and contents of Ag, Bi, Cd, Co, Cs, Ga, In, Rb, Se, Te, Tl and Zn-trace elements spanning the volatility/mobility range-in light and dark portions of H chondrite regolith breccias and L chondrite fragmental breccias are reported. The chemical/petrologic characteristics of H chondrite regolith breccias differ from those of nonbrecciated chondrites or fragmental breccias. Petrologic characteristics and at least some trace element contents of H chondrite regolith breccias reflect primary processes; contents of the most volatile/mobile elements may reflect either primary or secondary processing, possibly within layered H chondrite parent object(s). Chemical/petrologic differences existed in different regions of the parent(s). Regoligh formation and gardening and meteoroid compaction were not so severe as to alter compositions markedly.

  3. Metamorphic grade of organic matter in six unequilibrated ordinary chondrites

    NASA Astrophysics Data System (ADS)

    Quirico, E.; Raynal, P. I.; Bourot-Denise, M.

    2003-05-01

    The thermal metamorphism grade of organic matter (OM) trapped in 6 unequilibrated ordinary chondrites (UOCs) (Semarkona [LL 3.0], Bishunpur [L/LL 3.1], Krymka [LL 3.1], Chainpur [LL 3.4], Inman [L/LL 3.4], and Tieschitz [H/L 3.6]) has been investigated with Raman spectroscopy in the region of the first-order carbon bands. The carbonaceous chondrite Renazzo (CR2) was also investigated and used as a reference object for comparison, owing to the fact that previous studies pointed to the OM in this meteorite as being the most pristine among all chondrites. The results show that the OM thermal metamorphic grade: 1) follows the hierarchy Renazzo << Semarkona << other UOCs; 2) is well correlated to the petrographic type of the studied objects; and 3) is also well correlated with the isotopic enrichment 15N. These results are strikingly consistent with earlier cosmochemical studies, in particular, the scenario proposed by Alexander et al. (1998). Thermal metamorphism in the parent body appears as the main evolution process of OM in UOCs, demonstrating that nebular heating was extremely weak and that OM burial results in the destabilization of an initial isotopic composition with high D and 15N. Furthermore, the clear discrimination between Renazzo, Semarkona, and other UOCs shows: 1) Semarkona is a very peculiar UOC--by far the most pristine; and 2) Raman spectroscopy is a valid and valuable tool for deriving petrographic sub-types (especially the low ones) that should be used in the future to complement current techniques. We compare our results with other current techniques, namely, induced thermo-luminescence and opaques petrography. Other results have been obtained. First, humic coals are not strictly valid standard materials for meteoritic OM but are helpful in the study of evolutionary trends due to thermal metamorphism. Second, terrestrial weathering has a huge effect on OM structure, particularly in Inman, which is a find. Finally, the earlier statement that fine

  4. Paris vs. Murchison: Impact of hydrothermal alteration on organic matter in CM chondrites

    NASA Astrophysics Data System (ADS)

    Vinogradoff, V.; Le Guillou, C.; Bernard, S.; Binet, L.; Cartigny, P.; Brearley, A. J.; Remusat, L.

    2017-09-01

    Unravelling the origin of organic compounds that were accreted into asteroids requires better constraining the impact of asteroidal hydrothermal alteration on their isotopic signatures, molecular structures, and spatial distribution. Here, we conducted a multi-scale/multi-technique comparative study of the organic matter (OM) from two CM chondrites (that originate from the same parent body or from identical parent bodies that accreted the same mixture of precursors) and underwent a different degree of hydrothermal alteration: Paris (a weakly altered CM chondrite - CM 2.8) and Murchison (a more altered one - CM 2.5). The Paris insoluble organic matter (IOM) shows a higher aliphatic/aromatic carbon ratio, a higher radical abundance and a lower oxygen content than the Murchison IOM. Analysis of the OM in situ shows that two texturally distinct populations of organic compounds are present within the Paris matrix: sub-micrometric individual OM particles and diffuse OM finely distributed within phyllosilicates and amorphous silicates. These results indicate that hydrothermal alteration on the CM parent body induced aromatization and oxidation of the IOM, as well as a decrease in radical and nitrogen contents. Some of these observations were also reported by studies of variably altered fragment of Tagish Lake (C2), although the hydrothermal alteration of the OM in Tagish Lake was apparently much more severe. Finally, comparison with data available in the literature suggests that the parent bodies of other chondrite petrologic groups could have accreted a mixture of organic precursors different from that accreted by the parent body of CMs.

  5. Accretion and Preservation of Organic Matter in Carbonaceous Chondrites as Revealed by NanoSIMS Imaging.

    NASA Astrophysics Data System (ADS)

    Remusat, L.; Guan, Y.; Eiler, J.

    2008-12-01

    Carbonaceous chondrites are the most primitive known meteorites. Their parent bodies accreted several discrete components of the early solar system: CAIs, other silicates, oxides, sulfides, ice, organics, and noble gases. Radioactive decay of short live radionucleides quickly heated these parent bodies and drove thermal metamorphism and aqueous alteration of their constituents. Despite this post-acretionary modification, at least some components of the organic matter in the carbaceous chondrites retained distinctive isotopic and molecular properties that may relate to their pre-acretionary origins in the protosolar nebula or in the molecular cloud that gave birth to it [1]. These processes that gave rise to early solar-system organic matter and the extent to which it was modified by parent body processes are still a matter of debate [2]. We have acquired NanoSIMS images of matrices of several CI, CM, CR and CV chondrites to document, in- situ, the distribution of organics and their textural and chemical relationships to co-existing inorganic components. Importantly, we performed these analyses on essentially unmodified fragments of matrix material pressed into indium, rather than on extracts, which have been the focus of most previous work on meteoritic organic matter. Specifically, we simultaneously collected H, D, 12C, 18O, 26CN, 28Si and 32S with a spatial resolution of 200 nm. Inorganic constituents of the imaged domains were determined by SEM imaging and EDS analysis. We identify two textural classes of organic constituents: diffuse organic matter and organic particles ~ 1 micron in diameter. The particles are common and do not exhibit any textural association with any inorganic matrix constituent. This distribution is consistent with previous observations by fluorescence optical microscopy [3]. These organic particles are likely primarily composed of insoluble organic matter (IOM) that grew prior to accretion as pure organic particules and was preserved in

  6. Carbon, hydrogen and nitrogen isotopes in solvent-extractable organic matter from carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Becker, R. H.; Epstein, S.

    1982-01-01

    CCl4 and CH3OH solvent extractions were performed on the Murray, Murchison, Orgueil and Renazzo carbonaceous chondrites. Delta-D values of +300-+500% are found in the case of the CH3OH-soluble organic matter. The combined C, H and N isotope data makes it unlikely that the CH3OH-soluble components are derivable from, or simply related to, the insoluble organic polymer found in the same meteorites. A relation between the event that formed hydrous minerals in CI1 and CM2 meteorites and the introduction of water- and methanol-soluble organic compounds is suggested. Organic matter soluble in CCl4 has no N, and delta-C-13 values are lower than for CH3OH-soluble phases. It is concluded that there either are large isotopic fractionations for carbon and hydrogen between different soluble organic phases, or the less polar components are partially of terrestrial origin.

  7. Origin of magnetite and pyrrhotite in carbonaceous chondrites

    USGS Publications Warehouse

    Herndon, J.M.; Rowe, M.W.; Larson, E.E.; Watson, D.E.

    1975-01-01

    CARBONACEOUS chondrites, although comprising only about 2% of known meteorites, are extremely interesting for scientific investigation. Their mineral constitution, and the correspondence between their bulk chemical composition and the solar abundance of condensable elements, indicate that minimum chemical fractionation and thermal alteration have occurred. The mineral phases observed in these primitive chondrites are sufficiently unique, with respect to other meteorite classes, to have elicited considerable speculation about the physical environment in which they formed1-7. ?? 1975 Nature Publishing Group.

  8. Origins and Distribution of Chondritic Olivine Inferred from Wild 2 and Chondrite Matrix

    NASA Technical Reports Server (NTRS)

    Frank, D. R.; Zolensky, M. E.

    2014-01-01

    To date, only 180 particle impact tracks from Wild 2 have been extracted from the Stardust aerogel collector and even fewer have been thoroughly characterized. In order to provide a cohesive compositional dataset that can be compared to the meteorite record, we have made both major and minor element analyses (TEM/EDXS) of olivine and low-Ca pyroxene for 39 particles harvested from 26 tracks. However, the dearth of equivalent analyses for these phases in chondrite matrix hinders their comparison to the Wild 2 samples. To properly permit comparison of chondritic olivine and pyroxene to the Wild 2 samples, we have also provided a large, comprehensive EPMA dataset (greater than10(exp 3) analyses) of analogous grains (5-30 micrometers) isolated in L/LL3.0-4, CI, CM, CR, CH, CO, CV, Acfer 094, EH3, EL6, and Kakangari matrix

  9. Origin of petrofabrics and magnetic anisotropy in ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Sneyd, Deana S.; Mcsween, Harry Y., Jr.; Sugiura, Naoji; Strangway, David W.; Nord, Gordon L., Jr.

    1988-01-01

    Three-dimensional finite strain and magnetic susceptibility anisotropy have been determined for 15 ordinary chondrites. The axes of strain and magnetic ellipsoids roughly correlate in both magnitude and orientation. The shapes of these ellipsoids are generally oblate spheroids that define a dominant foliation and a weak lineation. These characteristics suggest deformation involving uniaxial compaction. The degree of uniaxial deformation correlates with intensity of shock, as indicated by optical, TEM and chemical criteria. These data, plus the lack of a relationship between foliation and metamorphic history, indicate that dynamic processes, i.e., impacts, produced planar deformation fabrics in chondrites.

  10. Origin of Chondrules and Matrix in Carbonaceous Chondrites

    NASA Astrophysics Data System (ADS)

    Palme, H.; Spettel, B.; Ikeda, Y.

    1993-07-01

    We have recently shown that in Allende, chondrules and matrix are complementary in composition. Chondrules have low Fe/Cr ratios and matrix has high Fe/Cr ratios; the bulk meteorite has the CI ratio. Chondrules on the average have Ca/Al ratios below the solar system ratio of 1.10, which is also the bulk Allende ratio; matrix and related dark inclusions have ratios above 1.10. It was therefore concluded that chondrules and matrix formed from a single reservoir characteristic of the bulk Allende composition [1,2]. Recent reports on the CV meteorite Y-86751 [3,4] indicated the opposite relationship, with high Ca/Al ratios in chondrules and low ratios in matrix. Different compositions of individual components of Y-86751 and of Allende but similar bulk compositions of both meteorites may reveal important details on the preaccretionary evolution of the carbonaceous chondrites. We have therefore begun chemical analyses of the bulk of Y-86751 and its individual lithic components, chondrules, matrix, amoeboid olivine inclusions, Ca,Al-rich inclusions, etc. Results of the bulk analysis of Y-86751 show that this meteorite has (within the accuracy of the analysis) the same bulk composition as Allende. In particular, the Ca/Al ratio is within 3% of the average solar system ratio of 1.1 (by weight). The only statistically resolvable difference is the 50% higher content of Zn in Y-86751. Major-element INA analyses indicate a Ca/Al ratio above the chondritic ratio for several chondrules and opposite to that of average Allende chondrules [1]. Matrix samples have a tendency for low Ca/Al ratios, confirming EMP-matrix analyses [4]. The separates are presently analyzed for a large number of trace elements. After the analyses, separates will be investigated petrographically. The apparent disequilibrium among Allende components and the strong compositional zoning of olivine grains constrain the thermal history of the Allende parent body [e.g., 5]. Any metamorphic redistribution of Ca or

  11. Crystallization trends of precursor pyroxene in ordinary chondrites: Implications for igneous origin of precursor

    NASA Technical Reports Server (NTRS)

    Fujita, T.; Kitamura, M.

    1994-01-01

    Various observations suggest that the precursor of the fine fragments and the relict pyroxene was formed by an igneous process in a grandparent body of the chondrite. Furthermore, the fact that the precursors appear as fragments in the matrix as well as relicts in the chondrule suggests a shock origin for the chondrite by collision of two or more bodies, which had already to some extent undergone igneous differentiation.

  12. Organic Matter Inclusions in CM2 Chondrite Murchison

    NASA Astrophysics Data System (ADS)

    Peeters, Z.; Liebig, B.; Lee, T.

    2015-07-01

    Large (~10 μm) inclusions of pure organic carbon exist in carbonaceous chondrites. We extracted organic inclusions from Murchison, a CM2, and analyzed the sections using XANES, TEM, and nanoSIMS. The results are compared to previous results of CRs.

  13. H-chondrites - Trace element clues to their origin

    NASA Technical Reports Server (NTRS)

    Morgan, J. W.; Janssens, M.-J.; Anders, E.; Takahashi, H.; Hertogen, J.

    1985-01-01

    RNAA is used to determine the abundances of 20 trace elements in four H4, two H3, two H5, and two H6 chondrites from the British Museum, as a contribution to a multiple-method study of these objects. The results are presented in tables and graphs and analyzed in terms of the inhomogeneity of the parent bodies and the depletion of volatiles in the higher petrologic types. Features observed include siderophile depletion in H3 chondrites; systematic variation of siderophile abundance pattern with petrologic type; volatile depletion as a primary feature; mineralogy consistent with accretion at 420-500 K; and the factor-analysis groupings siderophiles (Os, Re, Ir, Ni, Pd, Au, and Ge), volatiles (Ag, Br, In, Cd, Bi, and Tl), and alkalis (Rb and Cs).

  14. Chondrules in H3 chondrites - Textures, compositions and origins

    NASA Technical Reports Server (NTRS)

    Lux, G.; Keil, K.; Taylor, G. J.

    1981-01-01

    Compositional and textural variations among chondrules in unequilibrated (type 3) H-group chondrites are examined in order to determine possible relations between chondrule compositions and textures. Bulk compositions of polished thin sections of 90 individual chondrules and 16 compound chondrule sets from the Sharps, Tieschitz and Bremervorde chondrites were measured by broad-beam electron probe analyses; the chondrules were also classified petrographically as barred olivine, porphyritic olivine, porphyritic pyroxene, barred pyroxene, radiating pyroxene or fine-grained. The mean compositions of each type are found to be distinct as verified by discriminant analysis, despite a large scatter, with the olivine-rich chondrules characterized by low SiO2 and high FeO and MgO contents, greater concentrations of TiO2, Al2O3, Na2O and K2O, and lower Cr2O3 and MnO relative to pyroxene-rich chondrules. Data suggest that composition, together with cooling rate, has played a conspicuous role in producing observed chrondrule textures, and are consistent with chondrule formation from mixtures of differing fractions of high-, intermediate- and low-temperature nebular condensates that underwent melting in space.

  15. Nature and origin of matrix in the unique type 3 chondrite, Kakangari

    NASA Astrophysics Data System (ADS)

    Brearley, A. J.

    1989-09-01

    The characteristics of the matrix of the Kakangari type-3 chondrite were investigated using high-resolution TEM and AEM. It was found that the textural and mineralogical characteristics of the fine-grained matrix of Kakangari are different from those of the other chondrite groups. Unlike the matrix phases present in the CV3 and CO3 chondrites, the matrix mineralogy of Kakangari contains clear information regarding its possible origin and thermal history. Data obtained are most consistent with an origin of Kakangari by annealing, without melting at high temperature (possibly during a chondrule-forming thermal event), of clusters or aggregates of ultrafine-grained amorphous or crystalline phases. The precursor materials were most likely to have been a mixture of nebula and presolar dust. Chondrules in Kakangari were probably formed from identical precursors to the matrix, but reached temperatures sufficiently high to produce melting.

  16. In Situ Mapping of the Organic Matter in Carbonaceous Chondrites and Mineral Relationships

    NASA Technical Reports Server (NTRS)

    Clemett, Simon J.; Messenger, S.; Thomas-Keprta, K. L.; Ross, D. K.

    2012-01-01

    Carbonaceous chondrite organic matter represents a fossil record of reactions that occurred in a range of physically, spatially and temporally distinct environments, from the interstellar medium to asteroid parent bodies. While bulk chemical analysis has provided a detailed view of the nature and diversity of this organic matter, almost nothing is known about its spatial distribution and mineralogical relationships. Such information is nevertheless critical to deciphering its formation processes and evolutionary history.

  17. Possible interstellar origin of amino acids in carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Ellinger, Y.; Lattelais, M.; Pauzat, F.; Zanda, B.

    2007-12-01

    Amino acids are currently identified in carbonaceous chondrites but none are yet observed for sure in the interstellar medium. The question of the relative stability of these prebiotic compounds with respect to the other possible species of same chemical formula is addressed by means of quantum chemical simulations. It is shown that glycine, alanine and gamma-aminobutyric acid are far from being the most stable compounds of their respective families of isomers. By contrast protonated glycine, beta-alanine (more stable than the biological alpha-alanine) and gamma-aminobutyric acid are the most stable compounds that can be formed. These results suggest that amino acids could have been formed as protonated species in the interstellar medium and then incorporated in the meteorites where they are neutralized. Detecting protonated species is now a major objective.

  18. Enstatite chondrites - Trace element clues to their origin

    NASA Technical Reports Server (NTRS)

    Hertogen, J.; Janssens, M.-J.; Takahashi, H.; Morgan, J. W.; Anders, E.

    1983-01-01

    Three EH and three EL chondrites have been subjected to RNAA analysis for 20 trace elements, and interelement correlations were examined in order to assess the effects of nebular fractionation and metamorphism. The refractory siderophiles Ir, Os, and Re correlate with the normal siderophiles Ni, Pd, Au, Sb, and Ge, in ELs but not in EHs. The two element groups presumably condensed on separate phases at first, but concentrated in metal during metabolism. Volatiles are consistently more depleted in ELs than EHs. Strong correlations are found for In-Tl, Tl-Bi, and Zn-Cd-In, which are equally consistent with predicted condensation curves for the solar nebula and with volatilization curves for artificially heated Abee. The three factors accounting for 93 percent of variance reflect volatile, siderophile, and chalcophile behavior.

  19. A multi-step model for the origin of E3 (enstatite) chondrites

    NASA Astrophysics Data System (ADS)

    Hutson, Melinda; Ruzicka, Alex

    2000-05-01

    It appears that the mineralogy and chemical properties of type 3 enstatite chondrites could have been established by fractionation processes (removal of a refractory component, and depletion of water) in the solar nebula, and by equilibration with nebular gas at low-to-intermediate temperatures (~700-950 K). We describe a model for the origin of type 3 enstatite chondrites that for the first time can simultaneously account for the mineral abundances, bulk-chemistry, and phase compositions of these chondrites, by the operation of plausible processes in the solar nebula. This model, which assumes a representative nebular gas pressure of 10-5 bar, entails three steps: (1) initial removal of 56% of the equilibrium condensed phases in a system of solar composition at 1270 K; (2) an average loss of 80-85% water vapor in the remaining gas; and (3) two different closure temperatures for the condensed phases. The first step involves a "refractory-element fractionation" and is needed to account for the overall major-element composition of enstatite chondrites, assuming an initial system with a solar composition. The second step, water-vapor depletion, is needed to stabilize Si-bearing metal, oldhamite, and niningerite, which are characteristic minerals of the enstatite chondrites. Variations in closure temperatures are suggested by the way in which the bulk chemistry and mineral assemblages of predicted condensates change with temperature, and how these parameters correlate with the observations of enstatite chondrites. In general, most phases in type 3 enstatite chondrites appear to have ceased equilibrating with nebular gas at ~900-950 K, except for Fe-metal, which continued to partially react with nebular gas to temperatures as low as ~700 K.

  20. Origin of plagioclase-olivine inclusions in carbonaceous chondrites

    SciTech Connect

    Sheng, Y.J.; Hutcheon, I.D.; Wasserburg, G.J. )

    1991-02-01

    Plagioclase-Olivine Inclusions (POIs) are an abundant group of chondrule-like objects with igneous textures found in carbonaceous chondrites. POIs consist of plagioclase, olivine, pyroxene, and spinel, and cover a wide range of compositions between Type C Ca-Al-rich Inclusions (CAIs) and ferromagnesian chondrules. POIs are distinguished from CAIs by the absence of melilite, lack of refractory siderophile-rich opaque assemblages, more sodic plagioclase, and abundance of olivine and aluminousenstatite. Rare accessory minerals including armalcolite, zirconolite, rutile, and sapphirine are found in several POIs. The petrographic and chemical properties of POIs indicate that they are not condensates or evaporative residues but formed by melting or partial melting of pre-existing solids. Seven of fourteen POIs contain isotopically fractionated Mg, and despite their textures these POIs are not isotopically homogeneous. A comparison of the essential characteristics of POIs and CAIs suggests that the major processes leading to formation of POIs - including condensation, dust/gas fractionation, aggregation of chemically and isotopically disparate materials, and partial melting - are common to most CAIs and chondrules. We present a scenario for the formulation of these objects and conclude that the homogeneity of the final assemblage - CAI, POI, or chondrule - is primarily a reflection of the thermal history rather than the nature of precursor materials.

  1. Formation of insoluble organic matter in type-1 and -2 chondrites: Radiolytic or thermal processes?

    NASA Astrophysics Data System (ADS)

    Quirico, E.; Orthous-Daunay, F.; Beck, P.; Bonal, L.; Brunetto, R.; Dartois, E.; Pino, T.; Montagnac, G.; Rouzaud, J.; Engrand, C.; Duprat, J.

    2014-07-01

    Insoluble organic matter (IOM) extracted from primitive chondrites comes in the form of a polyaromatic solid with a structure and composition resembling that of terrestrial kerogens. It bears large D/H and ^{15}N/^{14}N isotopic ratios that point to a formation in a cold environment and ion-molecule reactions. However, the nature of the chemical and physical processes that led to its formation is still actively discussed: formation in the parent body by slight thermal metamorphism [1], inheritance from interstellar medium [2], or formation in the upper layer of the protosolar disk [3]. Post-accretional evolution of organic matter has also emerged as a critical issue, as it may disturb or even obscure pre-accretional information. In type 1 and 2 chondrites, evidence of short duration thermal heating of OM has been found using a variety of techniques [4]. In order to unravel pre-accretional from post-accretional processes, we have performed a survey of the composition and structure of IOM on a series of 27 CR, CM, CI, and ungrouped C2 carbonaceous chondrites (Tagish Lake, Bells, Essebi, Acfer 094) using infrared and multi-wavelength Raman micro-spectroscopy (244-, 514-, and 785-nm laser excitations [5]). Our results show that chondritic IOM from PCA 91008 (CM2), WIS 91600 (CM2), QUE 93005 (CM2), Tagish Lake (C2 ungrouped), and possibly Cold Bokkeveld (CM2) has been subjected to the past action of short-duration thermal metamorphism, presumably triggered by impacts. The IOM in most of the CM chondrites that experienced moderate to heavy aqueous alteration may have been slightly modified by collision-induced heating. Even IOM from chondrites that escaped significant thermal metamorphism (e.g., the most primitive CR chondrites) displays Raman characteristics consistent with a formation by thermal processing. This process may have happened either in the protosolar disk or in the parent body. However, an alternative energetic process to thermal heating is ion irradiation

  2. Carbon-rich aggregates in type 3 ordinary chondrites - Characterization, origins, and thermal history

    NASA Technical Reports Server (NTRS)

    Brearley, Adrian J.

    1990-01-01

    Carbon-rich aggregates from three type 3.4-3.6 ordinary chondrites and two chondritic clasts have been characterized in detail, using TEM techniques. The aggregates in all the meteorites studied range in size from 5-1000 microns and consist of a fine scale intergrowth of poorly graphitized carbon, amorphous carbon, Fe,Ni metal, and minor chromite. Contrary to previous reports, well-crystallized graphite and magnetite are absent. The association of Fe,Ni metal and carbonaceous material suggests that the original carbonaceous material may have formed by Fischer-Tropsch (FT) type reactions at low temperatures (less than 400 K), possibly in the solar nebula. This carbonaceous material probably consisted of a complex mixture of hydrocarbons, kerogen-like material, and other complex organic molecules. The aggregates were subsequently accreted onto the ordinary chondrite parent bodies and underwent planetary thermal processing which resulted in the catalytic graphitization of hydrocarbons, in the presence of Fe,Ni metal, to produce poorly graphitized carbon. None of the meteorites studied experienced temperatures sufficiently high to produce crystalline, ordered graphite. Using the empirical geothermometer of Rietmeijer and Mackinnon (1985), the measured d(002) spacings of poorly graphitized carbon show that graphitization occurred at temperatures between 300 and 450 C. This range of temperatures is significantly lower than the generally quoted metamorphic temperatures for type 3.4-3.6 ordinary chondrites (about 450-500 C).

  3. Clues to the origin of metal in Almahata Sitta EL and EH chondrites and implications for primitive E chondrite thermal histories

    NASA Astrophysics Data System (ADS)

    Horstmann, Marian; Humayun, Munir; Bischoff, Addi

    2014-09-01

    -accretionary origin of MSSIs in E chondrites is consistent with a growing body of evidence for early differentiation followed by impact disruption of early formed planetesimals in all major chondrite types.

  4. The deuterium/hydrogen distribution in chondritic organic matter attests to early ionizing irradiation

    PubMed Central

    Laurent, Boris; Roskosz, Mathieu; Remusat, Laurent; Robert, François; Leroux, Hugues; Vezin, Hervé; Depecker, Christophe; Nuns, Nicolas; Lefebvre, Jean-Marc

    2015-01-01

    Primitive carbonaceous chondrites contain a large array of organic compounds dominated by insoluble organic matter (IOM). A striking feature of this IOM is the systematic enrichment in deuterium compared with the solar hydrogen reservoir. This enrichment has been taken as a sign of low-temperature ion-molecule or gas-grain reactions. However, the extent to which Solar System processes, especially ionizing radiation, can affect D/H ratios is largely unknown. Here, we report the effects of electron irradiation on the hydrogen isotopic composition of organic precursors containing different functional groups. From an initial terrestrial composition, overall D-enrichments and differential intramolecular fractionations comparable with those measured in the Orgueil meteorite were induced. Therefore, ionizing radiation can quantitatively explain the deuteration of organics in some carbonaceous chondrites. For these meteorites, the precursors of the IOM may have had the same isotopic composition as the main water reservoirs of the inner Solar System. PMID:26461170

  5. Origins and Asteroid Main-Belt Stratigraphy for H-, L-, LL-Chondrite Meteorites

    NASA Astrophysics Data System (ADS)

    Binzel, Richard; DeMeo, Francesca; Burbine, Thomas; Polishook, David; Birlan, Mirel

    2016-10-01

    We trace the origins of ordinary chondrite meteorites to their main-belt sources using their (presumably) larger counterparts observable as near-Earth asteroids (NEAs). We find the ordinary chondrite stratigraphy in the main belt to be LL, H, L (increasing distance from the Sun). We derive this result using spectral information from more than 1000 near-Earth asteroids [1]. Our methodology is to correlate each NEA's main-belt source region [2] with its modeled mineralogy [3]. We find LL chondrites predominantly originate from the inner edge of the asteroid belt (nu6 region at 2.1 AU), H chondrites from the 3:1 resonance region (2.5 AU), and the L chondrites from the outer belt 5:2 resonance region (2.8 AU). Each of these source regions has been cited by previous researchers [e.g. 4, 5, 6], but this work uses an independent methodology that simultaneously solves for the LL, H, L stratigraphy. We seek feedback from the planetary origins and meteoritical communities on the viability or implications of this stratrigraphy.Methodology: Spectroscopic and taxonomic data are from the NASA IRTF MIT-Hawaii Near-Earth Object Spectroscopic Survey (MITHNEOS) [1]. For each near-Earth asteroid, we use the Bottke source model [2] to assign a probability that the object is derived from five different main-belt source regions. For each spectrum, we apply the Shkuratov model [3] for radiative transfer within compositional mixing to derive estimates for the ol / (ol+px) ratio (and its uncertainty). The Bottke source region model [2] and the Shkuratov mineralogic model [3] each deliver a probability distribution. For each NEA, we convolve its source region probability distribution with its meteorite class distribution to yield a likelihood for where that class originates. Acknowledgements: This work supported by the National Science Foundation Grant 0907766 and NASA Grant NNX10AG27G.References: [1] Binzel et al. (2005), LPSC XXXVI, 36.1817. [2] Bottke et al. (2002). Icarus 156, 399. [3

  6. Origin of Nanodiamonds in Primitive Chondrites: (2) Experiment

    NASA Astrophysics Data System (ADS)

    Mochizuki, K.; Ozima, M.; Tuchiyama, A.; Kitamura, M.; Shimobayashi, N.

    1993-07-01

    Ozima and Mochizuki [1] suggested that microdiamonds in primitive meteorites were formed by irradiation of carbonaceous matters such as graphite, amorphous carbon, or hydrocarbons with energetic particles emitted from supernova. To test this hypothesis, we carried out the following experiments. 1. We investigated a uranium-rich coal from Cluff Lake, Canada. Electron microprobe analysis of this sample showed that there are numerous uranium oxide grains of about 10-20 micrometers almost uniformly distributed in hydrocarbon matrix. A small amount of PbS was also identified by the EPMA analysis. If the U,Th-induced radiation were to produce diamonds, they must be found in radiation-damaged regions around the uranium oxide grains. Hence, we very carefully searched for microdiamonds in the radiation-damaged regions by TEM (transmission electron microscope). We observed many crystalline particles of about 20 nm, of which concentration in the radiation damaged region is about 500 ppm. Electron diffraction analysis with a TEM on the crystalline particles gave a powder ring pattern. Because of the limited resolution of the TEM, the electron diffraction was taken over an area (about 0.5 micrometers x 0.5 micrometers) that contained several grains. In Table 1, we show the spacing characteristics deduced from the diffraction analysis, where the observed d-spacings (denoted as D) are normalized to the table values corresponding to diamond, graphite, and PbS (denoted as d) respectively. If diamond is chosen for the normalization, the D/d ratios become almost constant for major diamond spacings, including the three most intense ones (shown by bold letters). One intense spacing at D = 1.887 angstroms, however, cannot be attributed to diamond, but may be due to PbS. We conclude that the observed electron diffraction pattern is primarily due to diamond, but other components such as PbS may also be present. Hence, the experiment seems to confirm Kaminsky's hypothesis [2] that high

  7. The Spatial Distribution of Organic Matter and Mineralogical Relationships in Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Clemett, S. J.; Messenger, S.; Thomas-Keprta, K. L.; Nakamura-Messenger, K.

    2012-01-01

    Organic matter present within primitive carbonaceous meteorites represents the complex conglomeration of species formed in a variety of physically and temporally distinct environments including circumstellar space, the interstellar medium, the Solar Nebula & Jovian sub-nebulae and asteroids. In each case, multiple chemical pathways would have been available for the synthesis of organic molecules. Consequently these meteorites constitute a unique record of organic chemical evolution in the Universe and one of the biggest challenges in organic cosmochemistry has been in deciphering this record. While bulk chemical analysis has provided a detailed description of the range and diversity of organic species present in carbonaceous chondrites, there is virtually no hard experimental data as to how these species are spatially distributed and their relationship to the host mineral matrix, (with one exception). The distribution of organic phases is nevertheless critical to understanding parent body processes. The CM and CI chondrites all display evidence of low temperature (< 350K) interaction with aqueous fluids, which based on O isotope data, flowed along thermal gradients within the respective parent bodies. This pervasive aqueous alteration may have led to aqueous geochromatographic separation of organics and synthesis of new organics coupled to aqueous mineral alteration. To address such issues we have applied the technique of microprobe two-step laser desorption / photoionization mass spectrometry (L2MS) to map in situ the spatial distribution of a broad range of organic species at the micron scale in the freshly exposed matrices of the Bells, Tagish Lake and Murchison (CM2) carbonaceous chondrites.

  8. A possible origin of EL6 chondrites from a high temperature-high pressure solar gas

    SciTech Connect

    Blander, M.; Unger, L.; Pelton, A.; Eriksson, G.

    1994-05-01

    Condensates from a gas of ``solar`` composition were calculated to investigate the origins of EL6 chondrites using a free energy minimization program with a data base for the thermodynamic properties of multicomponent molten silicates as well as for other liquids solids, solid solutions and gaseous species. Because of high volatility of silicon and silica, the high silicon content of metal (2.6 mole %) can only be produced at pressures 10{sup {minus}2} atm at temperatures above 1475 K. At 100--500 atm, a liquid silicate phase crystallizes at a temperature where the silicon content of the metal, ferrosilite content of the enstatite and albite concentration in the plagioclase are close to measured values. In pyrometallurgy, liquid silicates are catalysts for reactions in which Si-O-Si bridging bonds are broken or formed. Thus, one attractive mode for freezing in the compositions of these three phases is disappearance of fluxing liquid. If the plagioclase can continue to react with the nebula without a liquid phase, lower pressures of 10{sup {minus}1} to 1 atm might be possible. Even if the nebula is more reducing than a solar gas, the measured properties of EL6 chondrites might be reconciled with only slightly lower pressures (less than 3X lower). The temperatures would be about the same as indicated in our calculations since the product of the silicon content of the metal and the square of the ferrosilite content of the enstatite constitute a cosmothermometer for the mineral assemblage in EL6 chondrites.

  9. D-depleted organic matter and graphite in the Abee enstatite chondrite

    NASA Astrophysics Data System (ADS)

    Remusat, L.; Rouzaud, J.-N.; Charon, E.; Le Guillou, C.; Guan, Y.; Eiler, J. M.

    2012-11-01

    A combination of NanoSIMS and High resolution transmission electron microscopy (HRTEM) imaging along with Raman spectroscopy was used to characterize the carbonaceous phases in HF/HCl residue of the Abee enstatite chondrite. This acid residue hosts a very D-depleted component (δD = -480‰). This residue is a mixture of graphite and highly disordered insoluble organic matter. The latter exhibits a significant mesoporosity (i.e., 200-500 nm scale), and also shows concentric and elongated stacks of polyaromatic layers. Insoluble organic matter is shown to be the most D-depleted component in Abee. We also determined, by using NanoSIMS, carbon isotopic composition of graphite and insoluble organic matter in the acid residue (δ13C = -11.3 ± 2.9‰ and -28.4 ± 2.2‰, respectively). We identified graphite in metal-rich clasts and in the matrix of Abee, associated with enstatite, sulfide and metal, but we could not localize highly disordered organic matter in our section. Regardless, given the vulnerability of organic matter to thermal degradation, we suggest that it was added to Abee parent body during the latest stage of its formation, after any thermal metamorphism or partial melting of Abee parent body. A genetic link between organic matter and graphite in Abee is excluded based on our HRTEM and carbon isotopic data. The differences in carbon isotopic compositions between these phases are consistent with previous data obtained by stepwise heating experiments and indicate that graphite is not derived from a pure thermal solid-state graphitization of the organic matter. Rather, we suggest that graphite precipitated from a melt rich in C during the partial melting of the Abee parent body. Insoluble organic matter in Abee has the lowest D/H ratio among the extraterrestrial organics. Organics in most carbonaceous and ordinary chondrites are believed to have been subjected to irradiations in low temperature environments, resulting in a dramatic isotopic fractionation

  10. A refractory inclusion in the Kaba CV3 chondrite - Some implications for the origin of spinel-rich objects in chondrites

    NASA Technical Reports Server (NTRS)

    Fegley, B., Jr.; Post, J. E.

    1985-01-01

    The first detailed petrographic and mineralogical study of a Ca, Al-rich inclusion (CAI) from the Kaba CV3 chondrite is reported. This 'fine-grained' CAI contains abundant small, rounded, rimmed, spinel-rich objects which have important features in common with the spinel-rich objects in other carbonaceous and ordinary chondrites. These nodules are interpreted as fractionated distillation residues of primitive dust. However, the available data do not unambiguously rule out a condensation origin for at least some of these objects. Finally, the preservation of distinct diopside-hedenbergite rims on the spinel-rich bodies and the small grain size of many minerals in the CAI matrix material both suggest that the CAI accreted cool and had a relatively cool thermal history in the Kaba parent body.

  11. The Origin of Organic Matter in the Solar System: Evidence from Interplanetary Dust Particles

    NASA Technical Reports Server (NTRS)

    Flynn, G. J.; Keller, L. P.; Jacobsen, C.; Wirick, S.

    2001-01-01

    The origin of the organic matter in interplanetary materials has not been established. A variety of mechanisms have been proposed, with two extreme cases being a Fisher-Tropsch type process operating in the gas phase of the solar nebula or a Miller-Urey type process, which requires interaction with an aqueous fluid, presumably occurring on an asteroid. In the Fisher-Tropsch case, we might expect similar organic matter in hydrated and anhydrous interplanetary materials. However, aqueous alteration is required in the case of the Miller-Urey process, and we would expect to see organic matter preferentially in interplanetary materials that exhibit evidence of aqueous activity, such as the presence of hydrated silicates. The types and abundance of organic matter in meteorites have been used as an indicator of the origin of organic matter in the Solar System. Indigenous complex organic matter, including amino acids, has been found in hydrated carbonaceous chondrite meteorites, such as Murchison. Much lower amounts of complex organic matter, possibly only terrestrial contamination, have been found in anhydrous carbonaceous chondrite meteorites, such as Allende, that contain most of their carbon in elemental form. These results seem to favor production of the bulk of the organic matter in the Solar System by aqueous processing on parent bodies such as asteroids, a Miller-Urey process. However, the hydrated carbonaceous chondrite meteorites have approximately solar abundances of the moderately volatile elements, while all anhydrous carbonaceous chondrite meteorites have significantly lower contents of these moderately volatile elements. Two mechanisms, incomplete condensation or evaporation, both of which involve processing at approx. 1200 C, have been suggested to explain the lower content of the moderately volatile elements in all anhydrous meteorites. Additional information is contained in the original extended abstract.

  12. The Origin of Silica-Rich Chondrules and Clasts in Ordinary and Carbonaceous Chondrites

    NASA Astrophysics Data System (ADS)

    Ruzicka, A.; Boynton, W. V.

    1992-07-01

    Chondrules and clasts containing a silica mineral or a silica glass are a minor but important constituent in many ordinary (Planner, 1983; Brigham et al., 1986) and some carbonaceous (Olsen, 1983) chondrites, and have been considered somewhat enigmatic. The recent discovery of a large, silica-rich igneous clast in the Bovedy (L3) chondrite (Ruzicka and Boynton, 1992) sheds light on the possible origin of other silica-rich objects. As discussed in Ruzicka and Boynton (1992), the Bovedy clast probably crystallized from an Lchondrite silicate magma in a relatively large magma body that had previously undergone olivine fractionation. The existence of similar fractionating magmas can also account for the origin of other silica-rich objects, as shown below. Pyroxene-silica objects. Chondrules (drop-formed objects) and clasts (irregularly shaped objects) consisting essentially of a mixture of orthopyroxene (opx) and a silica mineral (SiO2) have been found in various ordinary chondrites (Brigham et al., 1986). Brigham and coworkers (1986) proposed that these objects could be condensates. However, fractional crystallization of a liquid similar in composition to the Bovedy clast (Ruzicka and Boynton, 1992) will produce (Morse, 1980) the following solids: (a) orthopyroxenite, (b) an opx + SiO2 rock, and (c) a feldspar, SiO2 and pyroxene rock. Brecciation or remelting of rock (b), which lies on the opx-SiO2 join in the cristobalite primary crystallization field, could have produced the pyroxene-silica objects of Brigham et al. (1986) and Planner (1983). Fayalite-silica clasts. These clasts consist of SiO2, olivine (ol, Fa(sub)63-96), and highly variable amounts of opx and clinopyroxene (Brigham et al., 1986). Brigham et al. (1986) discussed various origins for these objects and concluded that none were entirely satisfactory, but that an accidental mixture of the various phases in them was probably the best hypothesis. However, a rock mainly containing SiO2 and fayalitic ol (Fa

  13. Thermal history of type 3 chondrites from the Antarctic meteorite collection determined by Raman spectroscopy of their polyaromatic carbonaceous matter

    NASA Astrophysics Data System (ADS)

    Bonal, Lydie; Quirico, Eric; Flandinet, Laurène; Montagnac, Gilles

    2016-09-01

    This paper is focused on the characterization of the thermal history of 151 CV, CO and unequilibrated ordinary chondrites (UOCs) from the NASA Antarctic meteorite collection, using an approach based on the structure of the included polyaromatic carbonaceous matter determined by Raman spectroscopy. 114 out of these 151 chondrites provided Raman spectra of carbonaceous matter and allowing to assign a petrologic type, which mostly reflects the peak temperature experienced by the rock on the parent body. A thorough review of literature shows however that it is not possible to deduce a peak temperature because accurate calibration is not available. Twenty-three new weakly metamorphosed chondrites have been identified: MIL 07671 (CV3.1); DOM 08006 (CO3.0); DOM 03238, MIL 05024, MIL 05104, MIL 07193 (CO3.1); TIL 82408, LAR 06279 (LL3.05-3.1); EET 90628 (L3.0); GRO 06054, QUE 97008 (L3.05), ALHA 77176, EET 90066, LAR 04380, MET 96515, MIL 05050 (L3.1); ALHA 78133, EET 87735, EET 90909, LEW 87208, PRE 95401 (L3.05-3.1); MCY 05218 (H3.05-3.1) and MET 00506 (H3.1). This study confirms that the width of the D band (FWHMD) and the ratio of the peak intensity of the D and G bands (ID/IG) are the most adapted tracers of the extent of thermal metamorphism in type 3 chondrites. It also unambiguously shows, thanks to the large number of samples, that the width of the G band (FWHMG) does not correlate with the maturity of polyaromatic carbonaceous matter. This parameter is nevertheless very valuable because it shows that Raman spectra of CV chondrites preserve memory of either the metamorphic conditions (possibly oxidation controlled by aqueous alteration) or the nature of the organic precursor. Oxidation memory is our preferred interpretation, however an extensive petrologic characterization of this CV series is required to get firm conclusions. Pre-graphitic carbonaceous matter is reported in seven chondrites and is even the only carbonaceous material detected in the chondrites

  14. Short duration thermal metamorphism in CR chondrites

    NASA Astrophysics Data System (ADS)

    Briani, G.; Quirico, E.; Gounelle, M.; Paulhiac-Pison, M.; Montagnac, G.; Beck, P.; Orthous-Daunay, F.-R.; Bonal, L.; Jacquet, E.; Kearsley, A.; Russell, S. S.

    2013-12-01

    CR chondrites are considered as one of the most primitive classes of meteorites. Most of them experienced a mild aqueous alteration and show no evidence of significant effect of thermal metamorphism. We present here a search for low degree metamorphic effects in CR chondrites. We studied 15 CR chondrites using different metamorphic indicators: (1) structure and Ni content of metal grains; (2) hydration state of matrix; (3) structure and composition of organic matter. The different metamorphic indicators show that two of the analyzed CR chondrites, GRA 06100 and GRO 03116, experienced thermal metamorphism. Indeed, all of the metal grains in GRA 06100 and half of the metal grains in GRO 03116 show Ni-rich phases; the matrix of GRA 06100 is almost completely dehydrated, and the matrix of GRO 03116 is partially dehydrated; Raman spectra of organic matter in these two meteorites are clearly different from those obtained for organic matter in the other CR chondrites, which resemble Raman spectra of organic matter in unmetamorphosed, CM2 meteorites; IR spectra of insoluble organic matter extracted from GRA 06100 and GRO 03116 show lower carbonyl abundance and higher CH2/CH3 ratio with respect to organic matter of unmetamorphosed chondrites. The other CR chondrites analyzed here lack these characteristics and only show a few metal grains with Ni-rich inclusions. Our results also show that the metamorphic effects observed in GRA 06100 and GRO 03116 are different from those observed in type 3 chondrites, which experienced long-duration metamorphism of radiogenic origin. We infer that thermal processing in these two CRs extended over a short duration and was triggered by impacts.

  15. Structural and Functional Micro-Infrared Survey of Pristine Carbonaceous Chondrites Insoluble Organic Matter

    NASA Astrophysics Data System (ADS)

    Orthous-Daunay, F.-R.; Quirico, E.; Beck, P.; Brissaud, O.; Schmitt, B.

    2010-03-01

    We present a mid-infrared study of C2 and C1 chondrites IOM. All have similar aliphatic structure at 50°C under 10-7 mbar. Oxidized functions are depleted in less altered chondrites. 300°C heating in ambient air turns aliphatic chains to esters.

  16. Genesis of oil and hydrocarbon gases within Mars and carbonaceous chondrites from our solar system: organic origin (source rocks or direct biogenic sink?)

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Prasanta K.

    2011-10-01

    The petroleum hydrocarbons (oil and gas) and kerogen macromolecules are abundant within the extraterrestrial atmospheric particles. These hydrocarbons occur as reservoir of lakes and oceans or in hydrate forms on various planets (Earth, Mars, moons of Saturn and Jupiter), asteroid belts, carbonaceous chondrites, and as solid residue within the planets or moons in the Solar System and beyond. The abundance of PAHs in the outer Solar System may indicate that the genesis of these primitive biomarker hydrocarbons may have formed abiogenically much earlier (> 5Ga) than the formation of our Solar System (~ 5 Ga). However, the origin of petroleum on Earth is overwhelmingly connected to the biogenic organic matter that is related to source rocks (thermal degradation of macromolecular kerogen). This may show a similar genesis of the kerogen macromolecules and petroleum hydrocarbons (oil and gas) within the carbonaceous chondrites (CCs), Mars, and selected moons from Saturn and Jupiter. They may be biologically and genetically related. Recent evidence of the possible presence of source rocks (organic rich black carbonaceous rocks) and associated petroleum system elements within Eberswalde and Holden areas of Mars may indicate similar terrestrial associations. Similarly, studies of Carbonaceous Chondrites using biological, petrological, SEM/EDS, and petroleum geochemical methods may also indicate the presence of source rock macromolecule within the CCs. These studies pointed out two new issues: (1) approximately, the major part of the CCs possibly originated from archaea, bacteria, and primitive algal remains; and (2) three types of temperature events affecting the petroleum generation within these carbonaceous chondrites: (i) lower temperature events (<200oC) in comets and cooler asteroids or planets (examples: Murchison, Tagish Lake, Orgueil); (ii) intermediate temperature events (200 - 300oC) as associated within the deeper section of the comets, asteroids or planets

  17. The mineral chemistry and origin of inclusion matrix and meteorite matrix in the Allende CV3 chondrite

    NASA Technical Reports Server (NTRS)

    Kornacki, A. S.; Wood, J. A.

    1984-01-01

    The mineralogy and mineral chemistry of the inclusion and meteorite matrices in the Allende CV3 chondrite are described, and the physical and chemical parameters of the conventional equilibrium condensation model of the origin of chondrite meteorites are evaluated. An alternative model of the origin of the mafic constituent of Allende inclusions is presented, on the basis of a new model of chondrule petrogenesis and the physical evolution of the primitive solar nebula. The model shows that the mineral chemistry of the olivine matrix in Allende CV3 seems to preserve a good record of nebular and planetary processes, including: (1) vapor-to-solid condensation under relatively oxidizing nonequilibrium conditions; (2) Fe/Mg equilibration in the meteorite parent body; and (3) recrystallization and incipient melting in the solar nebula.

  18. The mineral chemistry and origin of inclusion matrix and meteorite matrix in the Allende CV3 chondrite

    NASA Technical Reports Server (NTRS)

    Kornacki, A. S.; Wood, J. A.

    1984-01-01

    The mineralogy and mineral chemistry of the inclusion and meteorite matrices in the Allende CV3 chondrite are described, and the physical and chemical parameters of the conventional equilibrium condensation model of the origin of chondrite meteorites are evaluated. An alternative model of the origin of the mafic constituent of Allende inclusions is presented, on the basis of a new model of chondrule petrogenesis and the physical evolution of the primitive solar nebula. The model shows that the mineral chemistry of the olivine matrix in Allende CV3 seems to preserve a good record of nebular and planetary processes, including: (1) vapor-to-solid condensation under relatively oxidizing nonequilibrium conditions; (2) Fe/Mg equilibration in the meteorite parent body; and (3) recrystallization and incipient melting in the solar nebula.

  19. Composition and clues to the origin of refractory metal nuggets extracted from chondritic meteorites

    NASA Astrophysics Data System (ADS)

    Schwander, D.; Berg, T.; Harries, D.; Schönhense, G.; Ott, U.

    2014-10-01

    Refractory metal nuggets (RMNs) contain elements, such as Os, Ir, Mo, and Ru, which are predicted to condense from a cooling gas of solar composition simultaneously with CAI-minerals. Berg et al. identified a large number of RMNs in acid-resistant residues of the Murchison meteorite and suggested that they are pristine condensates. In extending the work of these authors, we have improved the chemical extraction process to enrich the concentration of RMNs in the residue sample and prepared three additional RMN-rich residues from the chondritic meteorites Murchison, Allende, and Leoville. The results show that, while their origin is clearly solar, the compositions in detail of RMNs from all three meteorites do not match well with a simple condensation model based on equilibrium thermodynamics and ideal solid solution of all metals. Thus, we find that a primary formation by direct condensation, as suggested previously, is unlikely for most of the studied grains and that alternative scenarios should be considered in future work. The results also show that several, but not all, alloys from Allende and Leoville have undergone processes, such as metamorphic oxidation and sulfidization in the meteoritic environment, in which they lost, e.g., W and Mo. For Murchison and several Leoville and Allende RMNs, we propose a pristine nature.

  20. Chemical Heterogeneity of Organic Matter in Minimally-Heated CO Chondrites

    NASA Astrophysics Data System (ADS)

    De Gregorio, B. T.; Stroud, R. M.; Burgess, K. D.; Davidson, J.; Nittler, L. R.; Alexander, C. M. O'D.

    2015-07-01

    IOM from CO chondrites of low petrologic grade contain unusual S-rich organics with a compact texture. Aberration-corrected TEM-EELS indicates S in aromatic heterocycles. Nanoglobules in these residues contain more aromatic carbon than bulk IOM.

  1. Shape, metal abundance, chemistry, and origin of chondrules in the Renazzo (CR) chondrite

    SciTech Connect

    Ebel, D.S.; Weisberg, M.K.; Hertz, J.; Campbell, A.J.

    2009-03-31

    We used synchrotron X-ray microtomography to image in 3-dimensions (3D) eight whole chondrules in a {approx}1 cm{sup 3} piece of the Renazzo (CR) chondrite at {approx}17 {micro}m per volume element (voxel) edge. We report the first volumetric (3D) measurement of metal/silicate ratios in chondrules and quantify indices of chondrule sphericity. Volumetric metal abundances in whole chondrules range from 1 to 37 volume % in 8 measured chondrules and by inspection in tomography data. We show that metal abundances and metal grain locations in individual chondrules cannot be reliably obtained from single random 2D sections. Samples were physically cut to intersect representative chondrules multiple times and to verify 3D data. Detailed 2D chemical analysis combined with 3D data yield highly variable whole-chondrule Mg/Si ratios with a supra-chondritic mean value, yet the chemically diverse, independently formed chondrules are mutually complementary in preserving chondritic (solar) Fe/Si ratios in the aggregate CR chondrite. These results are consistent with localized chondrule formation and rapid accretion resulting in chondrule + matrix aggregates (meteorite parent bodies) that preserve the bulk chondritic composition of source regions.

  2. Origin of dark clasts in the ACFER 059/El Djouf 001 CR2 chondrite

    NASA Astrophysics Data System (ADS)

    Endress, M.; Keil, K.; Bischoff, A.; Spettel, B.; Clayton, R. N.; Mayeda, T. K.

    1994-01-01

    The ten specimens of the paired Acfer 059/El Djouf 001 CR2 chondrite contain abundant lithic fragments which we refer to as dark clasts. Petrological and mineralogical studies reveal that they are not related to the CR2 host meteorite but are similar to dark clasts in other CR2 chondrites. Dark clasts consist of chondrule and mineral fragments, phyllosilicate fragments and clusters, magnetite, sulfides and accessory phases, embedded into a very fine-grained, phyllosilicate-rich matrix. Magnetite has morphologies known from CI chondrites: spherules, framboids and platelets. Average abundances of major elements in the dark clasts are mostly in the range of both CR and CV chondrites, but strong depletions in Na and S are apparent. Oxygen isotopic compositions of two dark clasts suggest relationships to type 3 carbonaceous chondrites and dark inclusions in Allende. The dark clasts are clearly different in texture and mineralogical compositions from the host matrix of Acfer 059/El Djouf 001. Therefore, these dark clasts are xenoliths and are quite unlike the Acfer 059/El Djouf 001 CR2 host meteorite. We suggest that dark clasts accreted at the same time with all other components during the formation of Acfer 059/El Djouf 001 whole rock.

  3. The bulk valence state of Fe and the origin of water in chondrites

    NASA Astrophysics Data System (ADS)

    Sutton, S.; Alexander, C. M. O'D.; Bryant, A.; Lanzirotti, A.; Newville, M.; Cloutis, E. A.

    2017-08-01

    There is abundant petrologic evidence for the oxidation of Fe during the aqueous alteration of chondrites, and water must have been the oxidant for this process. The H2 lost from the chondrite parent bodies as a result of Fe oxidation would have been isotopically very light, enriching any residual water in D. The extents of the D enrichments will have depended on the fractions of water consumed and the temperatures during Fe oxidation. Here we have estimated the likely ranges of water consumed by Fe oxidation in the CI, CM, CR and LL parent bodies, as well as the likely range of changes in water H isotopic compositions this would have produced. We first used Fe XANES to determine the Fe valences of bulk meteorite powders in Orgueil (CI1), a number of CMs and CRs that experienced varying degrees of alteration, and Semarkona (LL3.00). The total ranges of bulk Fe valences we obtained were: Orgueil 2.77, CMs 2.40-2.63, CRs 1.46-2.54, and Semarkona 2.10. Combining previous estimates of the present water/OH contents of our samples with the present bulk Fe valences and an estimated range of initial bulk Fe valences, we estimate the likely ranges of fractional water losses to have been: Orgueil 15-26%, Semarkona 73-83%, CMs 23-48%, and CRs 39-62%. The associated maximum and minimum changes in the H isotopic compositions of the remaining water were estimated assuming the equilibrium H2-H2O isotopic fractionation factor, Rayleigh fractionation of the H2, and oxidation temperatures of 0-200 °C. Using previous estimates of the water H isotopic compositions in the chondrites, the ranges of estimated δD values for the initial chondritic waters are: Orgueil -672‰ to -422‰, CMs -676‰ to -493‰, CRs -527‰ to -56‰, and Semarkona -527‰ to 154‰. The CI, CM, CR and ordinary chondrites all accreted water with similar H isotopic compositions that were distinct from the compositions of comets or Saturn's moon Enceladus. Thus, the carbonaceous chondrites are unlikely to

  4. Identification and Characterization of Early Solar system Organic Matter Preserved in Chondritic Porous Interplanetary Dust Particles

    NASA Astrophysics Data System (ADS)

    Flynn, George; Wirick, Sue; Keller, Lindsay

    2015-04-01

    The chondritic porous interplanetary dust particles (CP IDPs), collected by NASA from the Earth's stratosphere, have experienced minimal aqueous or thermal alteration since their formation. These CP IDPs are the best preserved samples of the minerals and organic matter that was present in the primitive Solar Nebula that are currently available for laboratory analysis [1]. The ~10 μm CP IDPs are aggregates of tens-of-thousands of mostly sub-micron grains of diverse compositions and mineralogies. Many of the individual mineral grains are coated by a 50 to 200 nm thick rims of carbonaceous material, and other carbonaceous material occurs as larger, discrete subunits within the particles [2]. We characterize this carbonaceous material using two high-resolution, synchrotron-based instruments: a Scanning Transmission X-ray Microscope (STXM) to locate and map the carbon and to identify its major functional groups by X-ray Absorption Near-Edge Structure (XANES) spectroscopy, and a micro-Fourier Transform Infrared (μ-FTIR) spectrometer to further characterize the functional groups by mid-infrared spectroscopy. Carbon-XANES spectroscopy identifies the rims coating the individual grains in CP IDPs as organic matter, dominated by the C=C, likely C-rings, and the C=O functional groups [3]. This structure, with the organic rims being the contact surfaces between the grains, implies a 3-step formation sequence: grain condensation, organic rim emplacement, and, finally, aggregation of the grains to form the dust particles. This suggests these organic rims formed very early in the evolution of the Solar Nebula, after grain condensation but before grain aggregation [3]. These organic rims coat grains of diverse compositions, including silicates, sulfides, and carbonates, which is inconsistent with formation by Fischer-Tropsch-like, mineral-specific catalysis, one of the mechanisms suggested for the formation of primitive organic matter. Our observations are consistent with an

  5. Coordinated NanoSIMS and FIB-TEM analyses of organic matter and associated matrix materials in CR3 chondrites

    NASA Astrophysics Data System (ADS)

    Floss, Christine; Le Guillou, Corentin; Brearley, Adrian

    2014-08-01

    The organic matter in the primitive CR3 chondrites QUE 99177 and MET 00426 exhibits, as in other CR chondrites, N isotopic compositions characterized by large enrichments in 15N compared to solar. These enrichments are present in the matrices of these two meteorites as localized hotspots associated with C-rich grains, and larger, more diffuse regions with more modest enrichments in 15N. Occasionally depletions in 15N are also observed. FIB-TEM analysis of isotopically anomalous as well as isotopically normal C-rich grains from the matrix of MET 00426 shows that both types of grains consist of highly disordered organic matter that exhibits a variety of morphologies. There are no obvious correlations of isotopic composition with morphology, petrographic association or elemental composition. Large diffuse regions with modest 15N enrichments may be the result of fluid action that redistributed organic matter (and the associated 15N enrichments) in veins and cracks along grain boundaries. Grain formation likely occurred in a variety of environments (e.g., molecular clouds or the outer regions of the protosolar nebula) via UV photolysis of simpler precursor ices with variable isotopic compositions.

  6. Origin and history of chondrite regolith, fragmental and impact-melt breccias from Spain

    NASA Technical Reports Server (NTRS)

    Casanova, I.; Keil, K.; Wieler, R.; San Miguel, A.; King, E. A.

    1990-01-01

    Six ordinary chondrite breccias from the Museo Nacional de Ciencias Naturales, Madrid (Spain), are described and classified as follows: the solar gas-rich regolith breccia Oviedo (H5); the premetamorphic fragmental breccias Cabezo de Mayo (type 6, L-LL), and Sevilla (LL4); the fragmental breccias Canellas (H4) and Gerona (H5); and the impact melt breccia, Madrid (L6). It is confirmed that chondrites with typical light-dark structures and petrographic properties typical of regolith breccias may (Oviedo) or may not (Canellas) be solar gas-rich. Cabezo de Mayo and Sevilla show convincing evidence that they were assembled prior to peak metamorphism and were equilibrated during subsequent reheating. Compositions of olivine and low-Ca pyroxene in host chondrite and breccia clasts in Cabezo de Mayo are transitional between groups L and LL. It is suggested, based on mineralogic and oxygen isotopic compositions of host and clasts, that the rock formed on the L parent body by mixing, prior to peak metamorphism. This was followed by partial equilibrium of two different materials: the indigenous L chondrite host and exotic LL melt rock clasts.

  7. Origin and history of chondrite regolith, fragmental and impact-melt breccias from Spain

    NASA Technical Reports Server (NTRS)

    Casanova, I.; Keil, K.; Wieler, R.; San Miguel, A.; King, E. A.

    1990-01-01

    Six ordinary chondrite breccias from the Museo Nacional de Ciencias Naturales, Madrid (Spain), are described and classified as follows: the solar gas-rich regolith breccia Oviedo (H5); the premetamorphic fragmental breccias Cabezo de Mayo (type 6, L-LL), and Sevilla (LL4); the fragmental breccias Canellas (H4) and Gerona (H5); and the impact melt breccia, Madrid (L6). It is confirmed that chondrites with typical light-dark structures and petrographic properties typical of regolith breccias may (Oviedo) or may not (Canellas) be solar gas-rich. Cabezo de Mayo and Sevilla show convincing evidence that they were assembled prior to peak metamorphism and were equilibrated during subsequent reheating. Compositions of olivine and low-Ca pyroxene in host chondrite and breccia clasts in Cabezo de Mayo are transitional between groups L and LL. It is suggested, based on mineralogic and oxygen isotopic compositions of host and clasts, that the rock formed on the L parent body by mixing, prior to peak metamorphism. This was followed by partial equilibrium of two different materials: the indigenous L chondrite host and exotic LL melt rock clasts.

  8. Origin and history of chondrite regolith, fragmental and impact-melt breccias from Spain

    NASA Astrophysics Data System (ADS)

    Casanova, I.; Keil, K.; Wieler, R.; San Miguel, A.; King, E. A.

    1990-06-01

    Six ordinary chondrite breccias from the Museo Nacional de Ciencias Naturales, Madrid (Spain), are described and classified as follows: the solar gas-rich regolith breccia Oviedo (H5); the premetamorphic fragmental breccias Cabezo de Mayo (type 6, L-LL), and Sevilla (LL4); the fragmental breccias Canellas (H4) and Gerona (H5); and the impact melt breccia, Madrid (L6). It is confirmed that chondrites with typical light-dark structures and petrographic properties typical of regolith breccias may (Oviedo) or may not (Canellas) be solar gas-rich. Cabezo de Mayo and Sevilla show convincing evidence that they were assembled prior to peak metamorphism and were equilibrated during subsequent reheating. Compositions of olivine and low-Ca pyroxene in host chondrite and breccia clasts in Cabezo de Mayo are transitional between groups L and LL. It is suggested, based on mineralogic and oxygen isotopic compositions of host and clasts, that the rock formed on the L parent body by mixing, prior to peak metamorphism. This was followed by partial equilibrium of two different materials: the indigenous L chondrite host and exotic LL melt rock clasts.

  9. Neodymium isotope heterogeneity of ordinary and carbonaceous chondrites and the origin of non-chondritic 142Nd compositions in the Earth

    NASA Astrophysics Data System (ADS)

    Fukai, Ryota; Yokoyama, Tetsuya

    2017-09-01

    We present high-precision Nd isotope compositions for ordinary and carbonaceous chondrites determined using thermal ionization mass spectrometry with dynamic and multistatic methods. The ordinary chondrites had uniform and non-terrestrial μ142 Nd , μ148 Nd , and μ150 Nd values, with data that plot along the mixing line between s-process and terrestrial components in μ150 Nd versus μ148 Nd and μ142 Nd versus μ148,150Nd diagrams. In contrast, the carbonaceous chondrites were characterized by larger anomalies in their μ142 Nd , μ148 Nd , and μ150 Nd values compared to ordinary chondrites. Importantly, the data for carbonaceous chondrites plot along the s-process and terrestrial mixing line in a μ150 Nd versus μ148 Nd diagram, whereas they have systematically lower μ142 Nd values than the s-process and terrestrial mixing line in μ142 Nd versus μ148,150Nd diagrams. This shift likely results from the incorporation of calcium- and aluminum-rich inclusions (CAIs), indicating that the Nd isotopic variability in the ordinary chondrites and CAI-free carbonaceous chondrites was caused solely by the heterogeneous distribution of s-process nuclides. The isotopic variation most likely results from nebular thermal processing that caused selective destruction of s-process-depleted (or r-process-enriched) dust grains in the inner Solar System where the parent bodies of ordinary chondrites formed, whereas such grains were preserved in the region of carbonaceous chondrite parent body formation. The Nd isotope dichotomy between ordinary and bulk aliquots of carbonaceous chondrites can be related to the presence of Jupiter, which may have separated two isotopically distinct reservoirs that were present in the solar nebula. After correcting for s-process anomalies and CAI contributions to the Nd isotopes observed in the chondrites, we obtained a μ142 Nd value (- 2.4 ± 4.8 ppm) that was indistinguishable from the terrestrial value. Our results corroborate the

  10. HRTEM and EFTEM Studies of Phyllosilicate-Organic Matter Associations in Matrix and Dark Inclusions in the EET92042 CR2 Carbonaceous Chondrite

    NASA Technical Reports Server (NTRS)

    Abreu, Neyda M.; Brearley, Adrian J.

    2005-01-01

    Based on petrologic and isotopic observations, the CR chondrites represent one of the most primitive carbonaceous chondrite groups. The organic matter in CR chondrite matrices is considered to be among the most ancient carbonaceous matter known, potentially providing a link between organic matter in the interstellar medium and our solar system [1]. However, the organic chemistry of CR chondrites may be complicated by the fact that these meteorites have undergone moderate secondary alteration, which potentially overprints primordial features [2]. Although the general effects of this alteration have been documented [2], the details of the fine-grained mineralogy and alteration styles of CR matrices are not fully understood. Here we present TEM observations of matrix in EET 92042, a CR chondrite that contains particularly primitive insoluble organic matter [1]. Preliminary studies [3] determined that EET 92042 matrix is heterogeneous in terms of mineralogy, texture, and petrographic fabric on the micron scale. EET 92042 contains magnetite-rich regions, foliated matrix and dark inclusions (DIs). Some chondrules show fine-grained rims, similar to those described by [4].

  11. Origins and challenges of viral dark matter.

    PubMed

    Krishnamurthy, Siddharth R; Wang, David

    2017-07-15

    The accurate classification of viral dark matter - metagenomic sequences that originate from viruses but do not align to any reference virus sequences - is one of the major obstacles in comprehensively defining the virome. Depending on the sample, viral dark matter can make up from anywhere between 40 and 90% of sequences. This review focuses on the specific nature of dark matter as it relates to viral sequences. We identify three factors that contribute to the existence of viral dark matter: the divergence and length of virus sequences, the limitations of alignment based classification, and limited representation of viruses in reference sequence databases. We then discuss current methods that have been developed to at least partially circumvent these limitations and thereby reduce the extent of viral dark matter. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Non-nebular Origin of Dark Mantles Around Chondrules and Inclusions in CM Chondrites

    NASA Technical Reports Server (NTRS)

    Trigo-Rodriquez, Josep M.; Rubin, Alan E.; Wasson, John T.

    2006-01-01

    Our examination of nine CM chondrites that span the aqueous alteration sequence leads us to conclude that compact dark fine mantles surrounding chondrules and inclusions in CM chondrites are not discrete fine-grained rims acquired in the solar nebula as modeled by Metzler et al. [Accretionary dust mantles in CM chondrites: evidence for solar nebula processes. Geochim. Cosmochim. Acta 56, 1992, 2873-28971. Nebular processes that lead to agglomeration produce materials with porosities far higher than those in the dark mantles. We infer that the mantles were produced from porous nebular materials on the CM parent asteroid by impact-compaction (a process that produces the lowest porosity adjacent to chondrules and inclusions). Compaction was followed by aqueous alteration that formed tochilinite, serpentine, Ni-bearing sulfide, and other secondary products in voids in the interchondrule regions. Metzler et al. reported a correlation between mantle thickness and the radius of the enclosed object. In Yamato 791 198 we find no correlation when all sizes of central objects and dark lumps are included but a significant correlation (r(sup 2) = 0.44) if we limit consideration to central objects with radii >35 microns; a moderate correlation is also found in QUE 97990. We suggest that impact-induced shear of a plum-pudding-like precursor produced the observed "mantles"; these were shielded from comminution during impact events by the adjacent stronger chondrules and inclusions. Some mantles in CM chondrites with low degrees of alteration show distinct layers that may largely reflect differences in porosity. Typically, a gray, uniform inner layer is surrounded by an outer layer consisting of darker silicates with BSE-bright speckles. The CM-chondrite objects characterized as "primary accretionary rocks" by Metzler et al. did not form in the nebula, but rather on the parent body. The absence of solar-flare particle tracks and solar-wind-implanted rare gases in these clasts

  13. Non-nebular Origin of Dark Mantles Around Chondrules and Inclusions in CM Chondrites

    NASA Technical Reports Server (NTRS)

    Trigo-Rodriquez, Josep M.; Rubin, Alan E.; Wasson, John T.

    2006-01-01

    Our examination of nine CM chondrites that span the aqueous alteration sequence leads us to conclude that compact dark fine mantles surrounding chondrules and inclusions in CM chondrites are not discrete fine-grained rims acquired in the solar nebula as modeled by Metzler et al. [Accretionary dust mantles in CM chondrites: evidence for solar nebula processes. Geochim. Cosmochim. Acta 56, 1992, 2873-28971. Nebular processes that lead to agglomeration produce materials with porosities far higher than those in the dark mantles. We infer that the mantles were produced from porous nebular materials on the CM parent asteroid by impact-compaction (a process that produces the lowest porosity adjacent to chondrules and inclusions). Compaction was followed by aqueous alteration that formed tochilinite, serpentine, Ni-bearing sulfide, and other secondary products in voids in the interchondrule regions. Metzler et al. reported a correlation between mantle thickness and the radius of the enclosed object. In Yamato 791 198 we find no correlation when all sizes of central objects and dark lumps are included but a significant correlation (r(sup 2) = 0.44) if we limit consideration to central objects with radii >35 microns; a moderate correlation is also found in QUE 97990. We suggest that impact-induced shear of a plum-pudding-like precursor produced the observed "mantles"; these were shielded from comminution during impact events by the adjacent stronger chondrules and inclusions. Some mantles in CM chondrites with low degrees of alteration show distinct layers that may largely reflect differences in porosity. Typically, a gray, uniform inner layer is surrounded by an outer layer consisting of darker silicates with BSE-bright speckles. The CM-chondrite objects characterized as "primary accretionary rocks" by Metzler et al. did not form in the nebula, but rather on the parent body. The absence of solar-flare particle tracks and solar-wind-implanted rare gases in these clasts

  14. Origin and Evolution of Prebiotic Organic Matter as Inferred from the Tagish Lake Meteorite

    NASA Technical Reports Server (NTRS)

    Herd, Christopher D.; Blinova, Alexandra; Simkus, Danielle N.; Huang, Yongsong; Tarozo, Rafael; Alexander, Conel M.; Gyngard, Frank; Nittler, Larry R.; Cody, George D.; Fogel, Marilyn L.; hide

    2011-01-01

    The complex suite of organic materials in carbonaceous chondrite meteorites probably originally formed in the interstellar medium and/or the solar protoplanetary disk, but was subsequently modified in the meteorites' asteroidal parent bodies. The mechanisms of formation and modification are still very poorly understood. We carried out a systematic study of variations in the mineralogy, petrology, and soluble and insoluble organic matter in distinct fragments of the Tagish Lake meteorite. The variations correlate with indicators of parent body aqueous alteration and at least some molecules of pre-biotic importance formed during the alteration.

  15. Examination of organic compounds from insoluble organic matter isolated from some Antarctic carbonaceous chondrites by heating experiments

    NASA Astrophysics Data System (ADS)

    Komiya, M.; Shimoyama, A.; Harada, K.

    1993-02-01

    Insoluble organic matter isolated from five Antarctic CM2 chondrites was heated in a thermal analyzer from room temperature to 800 C under helium atmosphere. Organic compounds from the thermal decomposition of the Yamato-791198 sample were studied by a gas chromatograph-mass spectrometer (GC-MS). The number of compounds identified was over 120, belonging mainly to the two following groups: (1) benzene and naphthalene, and their alkyl derivatives; and (2) sulfur-containing heterocycles and their alkyl derivatives. Small amounts of aliphatic hydrocarbons and nitriles were also detected. Relative amounts of compounds released from the five chondrite samples were monitored by the MS with increasing temperature. Yamato-74662 and Yamato-791198 showed organic compounds mainly over the temperature range of 300-600 C, while the other three (Yamato-793321, Yamato-86720, and Belgica-7904) did not show any, except small amounts of benzene. These results indicate that the insoluble organics in Yamato-74662 and Yamato-791198 possess a thermally labile organic fraction, whereas those in Yamato-793321, Yamato-86720, and Belgica-7904 do not and are graphitic. The difference between the insoluble organic fractions may be related to aqueous alteration and thermal metamorphism on the parent bodies.

  16. 3D shape of asteroid (6) Hebe from VLT/SPHERE imaging: Implications for the origin of ordinary H chondrites

    NASA Astrophysics Data System (ADS)

    Marsset, M.; Carry, B.; Dumas, C.; Hanuš, J.; Viikinkoski, M.; Vernazza, P.; Müller, T. G.; Delbo, M.; Jehin, E.; Gillon, M.; Grice, J.; Yang, B.; Fusco, T.; Berthier, J.; Sonnett, S.; Kugel, F.; Caron, J.; Behrend, R.

    2017-08-01

    Context. The high-angular-resolution capability of the new-generation ground-based adaptive-optics camera SPHERE at ESO VLT allows us to assess, for the very first time, the cratering record of medium-sized (D 100-200 km) asteroids from the ground, opening the prospect of a new era of investigation of the asteroid belt's collisional history. Aims: We investigate here the collisional history of asteroid (6) Hebe and challenge the idea that Hebe may be the parent body of ordinary H chondrites, the most common type of meteorites found on Earth ( 34% of the falls). Methods: We observed Hebe with SPHERE as part of the science verification of the instrument. Combined with earlier adaptive-optics images and optical light curves, we model the spin and three-dimensional (3D) shape of Hebe and check the consistency of the derived model against available stellar occultations and thermal measurements. Results: Our 3D shape model fits the images with sub-pixel residuals and the light curves to 0.02 mag. The rotation period (7.274 47 h), spin (ECJ2000 λ, β of 343°, +47°), and volume-equivalent diameter (193 ± 6 km) are consistent with previous determinations and thermophysical modeling. Hebe's inferred density is 3.48 ± 0.64 g cm-3, in agreement with an intact interior based on its H-chondrite composition. Using the 3D shape model to derive the volume of the largest depression (likely impact crater), it appears that the latter is significantly smaller than the total volume of close-by S-type H-chondrite-like asteroid families. Conclusions: Our results imply that (6) Hebe is not the most likely source of H chondrites. Over the coming years, our team will collect similar high-precision shape measurements with VLT/SPHERE for 40 asteroids covering the main compositional classes, thus providing an unprecedented dataset to investigate the origin and collisional evolution of the asteroid belt. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory

  17. Silica-merrihueite/roedderite-bearing chondrules and clasts in ordinary chondrites: New occurrences and possible origin

    NASA Technical Reports Server (NTRS)

    Krot, Alexander N.; Wasson, John T.

    1994-01-01

    Merrihueite (K,Na)2(Fe,Mg)5Si12O30 (na less than 0.5, fe greater than 0.5, where na = Na/(Na + K), fe = Fe/(Fe + Mg) in atomic ratio) is a rare mineral described only in several chondrules and irregularly-shaped fragments in the Mezo-Madaras L3 chondrite (Dodd et al., 1965; Wood and Holmberg, 1994). Roedderite (Na,K)2(Mg,Fe)5Si12O30 (na greater than 0.5, fe less than 0.5) has been found only in enstatite chondrites and in the reduced, subchondritic silicate inclusions in IAB irons (Fuchs, 1966; Rambaldi et al., 1984; Olsen, 1967). We described silica-roedderite-bearing clasts in L/LL3.5 ALHA77011 and LL3.7 ALHA77278, a silica-roedderite-bearing chondrule in L3 Mezo-Madaras, and a silica-merrihueite-bearing chondrule in L/LL3.5 ALHA77115. The findings of merrihueite and roedderite in ALHA77011, ALHA77115, ALHA77278 and Mezo-Madaras fill the compositional gap betweeen previously described roedderite in enstatite chondrites and silicate inclusions in IAB irons and merrihueite in Mezo-Madaras, suggesting that there is a complete solid solution of roedderite and merrihueite in meteorites. We infer that the silica- and merrihueite/roedderite-bearing chondrules and clasts experienced a complex formational history including: (a) fractional condensation in the solar nebular that produced Si-rich and Al-poor precursors, (b) melting of fractionated nebular solids resulting in the formation of silica-pyroxene chondrules, (c) in some cases, fragmentation in the nebula or on a parent body, (d) reaction of silica with alkali-rich gas that formed merrihueite/roedderite on a parent body, (e) formation of fayalitic olivine and feerosilite-rich pyroxene due to reaction of silica with oxidized Fe on a parent body, and (f) minor thermal metamorphism, possibly generated by impacts.

  18. Evidence against a chondritic Earth.

    PubMed

    Campbell, Ian H; O'Neill, Hugh St C

    2012-03-28

    The (142)Nd/(144)Nd ratio of the Earth is greater than the solar ratio as inferred from chondritic meteorites, which challenges a fundamental assumption of modern geochemistry--that the composition of the silicate Earth is 'chondritic', meaning that it has refractory element ratios identical to those found in chondrites. The popular explanation for this and other paradoxes of mantle geochemistry, a hidden layer deep in the mantle enriched in incompatible elements, is inconsistent with the heat flux carried by mantle plumes. Either the matter from which the Earth formed was not chondritic, or the Earth has lost matter by collisional erosion in the later stages of planet formation.

  19. Petrography and origin of refractory inclusions from the Murray and Murchison C2 chondrites

    NASA Technical Reports Server (NTRS)

    Simon, S. B.; Grossman, L.; Hsu, A.

    1993-01-01

    By freeze-thaw disaggregation, we have recovered a total of 47 refractory inclusions. New discoveries include the following: a hibonite-pyroxene spherule from Murray; a CaAl4O7-bearing spherule from Murchison; and a Sc-fassaite-bearing ultrarefractory inclusion from Murchison. Freeze-thaw disaggregation, combined with density separation and hand-picking as described is a proven method for recovering rare objects from carbonaceous chondrites. This method is especially effective on C2's due to their porosity and typically results in the discovery of new types of refractory inclusions. Because few refractory inclusions from Murray have been described, we studied this meteorite, although only a small amount of material (730 mg) was available for disaggregation. Many refractory inclusions from Murchison have been described, and we disaggregated a larger amount (approximately 18 g) of Murchison in an attempt to find new types of refractory inclusions, especially corundum-bearing ones.

  20. Petrography and origin of refractory inclusions from the Murray and Murchison C2 chondrites

    NASA Technical Reports Server (NTRS)

    Simon, S. B.; Grossman, L.; Hsu, A.

    1993-01-01

    By freeze-thaw disaggregation, we have recovered a total of 47 refractory inclusions. New discoveries include the following: a hibonite-pyroxene spherule from Murray; a CaAl4O7-bearing spherule from Murchison; and a Sc-fassaite-bearing ultrarefractory inclusion from Murchison. Freeze-thaw disaggregation, combined with density separation and hand-picking as described is a proven method for recovering rare objects from carbonaceous chondrites. This method is especially effective on C2's due to their porosity and typically results in the discovery of new types of refractory inclusions. Because few refractory inclusions from Murray have been described, we studied this meteorite, although only a small amount of material (730 mg) was available for disaggregation. Many refractory inclusions from Murchison have been described, and we disaggregated a larger amount (approximately 18 g) of Murchison in an attempt to find new types of refractory inclusions, especially corundum-bearing ones.

  1. Early Archean Spherule Beds: Chromium Isotopes Confirm Origin through Multiple Impacts of Projectiles of Carbonaceous Chondrite Type: Comment and Reply

    NASA Technical Reports Server (NTRS)

    Kyte, Frank T.

    2003-01-01

    This is a exchange in the form of a comment and a reply in regards to an earlier article. The authors of the original article, consider it likely that virtually all of the projectile will condense with the silicate fraction, resulting in very little platinum group element fractionation in the final ejecta deposit. Further, we find no evidence in the commentator's, (i.e., Glikson), comment to support vapor fractionation. We note that the Pd/Ir ratios of published data on 2.56 Ga Hamersley Basin spherules are all greater than in chondrites, contrary to the assertion by Glikson. This is consistent with relatively high Pd concentrations (and Pd/Ir ratios) in crustal rocks.

  2. Early Archean Spherule Beds: Chromium Isotopes Confirm Origin through Multiple Impacts of Projectiles of Carbonaceous Chondrite Type: Comment and Reply

    NASA Technical Reports Server (NTRS)

    Kyte, Frank T.

    2003-01-01

    This is a exchange in the form of a comment and a reply in regards to an earlier article. The authors of the original article, consider it likely that virtually all of the projectile will condense with the silicate fraction, resulting in very little platinum group element fractionation in the final ejecta deposit. Further, we find no evidence in the commentator's, (i.e., Glikson), comment to support vapor fractionation. We note that the Pd/Ir ratios of published data on 2.56 Ga Hamersley Basin spherules are all greater than in chondrites, contrary to the assertion by Glikson. This is consistent with relatively high Pd concentrations (and Pd/Ir ratios) in crustal rocks.

  3. The Origin of Chondrites: Metal-Silicate Separation Experiments Under Microgravity Conditions, Experiment 2

    NASA Technical Reports Server (NTRS)

    Moore, S. R.; Franzen, M.; Benoit, P. H.; Sears, D. W. G.; Holley, A.; Myers, M.; Godsey, R.; Czlapinski, J.

    2003-01-01

    Chondrites are categorized into different groups by several properties, including the metal-to-silicate ratio. Various processes have been suggested to produce distinct metal/silicate ratios, some based on sorting in the early solar nebular and others occurring after accretion on the parent body. Huang et al. suggested that a weak gravitational field accompanied by degassing, could result in metal/silicate separation on parent bodies. We suggest that asteroids were volatile-rich, at least early in their histories. Spectroscopic evidence from asteroid surfaces indicates that one-third of all asteroids maybe rich in clays and hydrated minerals, similar to carbonaceous chondrites. Internal and/or external heating could have caused volatiles to evaporate and pass through a surface dust layer. Spacecraft images of asteroids show they have a thick regoliths. Housen, and Asphaug and Nolan proposed that even a 10 km diameter asteroid could potentially have a significant regolith. Grain size and grain density sorting could occur in the unconsolidated layer by the process known as fluidization. This process occurs when an upward stream of gas is passed through a bed of particles which are lifted against a gravitational force. Fluidization is commonly used commercially to sort particulates. This type of behavior is based upon the bed, as a whole, and differs from aerodynamic sorting. Two sets of reduced gravity experiments were conducted during parabolic flights aboard NASA's KC-135 aircraft. The first experiment employed 310 tubes of 2.5 cm diameter, containing mixtures of sand and metal grains. A gas source was used to fluidize the mixture at reduced gravity conditions and mixtures were analyzed after the flight. However, this experiment did not allow a description of the fluidization as a function of gravity. A second experiment was conducted on the KC-135 aircraft in the summer of 2001, consisting of two Plexiglas cylinders containing a metal/silicate mixture, and video

  4. Origin of mass-independent oxygen isotope variation among ureilites: Clues from chondrites and primitive achondrites

    NASA Astrophysics Data System (ADS)

    Sanders, I. S.; Scott, E. R. D.; Delaney, J. S.

    2017-04-01

    Ureilite meteorites are abundant, carbon-rich, primitive achondrites made of coarse-grained, equilibrated olivine and pyroxene (usually pigeonite). They probably sample the baked, heterogeneous, melt-depleted mantle of a large, once-chondritic parent body that was broken up catastrophically while still young and hot. Heterogeneity in the parent body is inferred from a considerable "slope-1" variation from one meteorite to another in oxygen isotopes (-2.5‰ < Δ17O < -0.2‰), which correlates with both molar FeO/MgO (range 0.03-0.35) and molar FeO/MnO (range 3-57), i.e., Δ17O correlates with the redox state. No consensus has yet emerged on the cause of these correlated trends. One view favors their inheritance via silicates from hot nebular (preaccretion) processes. Another invokes smelting (reduction of FeO by C in the hot parent body). Here, guided mainly by similar trends among equilibrated ordinary and R chondrites, studies of their unequilibrated counterparts, and work on other primitive achondrites, we propose a new model for ureilites in which the parent body accreted nebular ice with high-∆17O, Mg-rich silicates with low ∆17O, and varying amounts of metallic iron. Water from the thawing ice then oxidized the metal yielding secondary FeO-bearing minerals with high ∆17O that, with metamorphism, became incorporated into the ureilite silicates. FeO/MgO, FeO/MnO, and ∆17O correlate because they rose in unison by amounts that varied spatially, depending on the local amount of metal that was oxidized. We suggest that the parent body was so large (radius ≫ 100 km) that smelting was inhibited and that carbon played a passive role in ureilite evolution. Although ureilites are regarded as complicated meteorites, we believe our analysis explains their mass-independent oxygen isotope trend and related FeO variation through well-understood processes and enlightens our understanding of the evolution of early planetesimals from cold, wet bodies to hot, dry ones.

  5. The Origin of Chondrites: Metal-Silicate Separation Experiments Under Microgravity Conditions, Experiment 2

    NASA Technical Reports Server (NTRS)

    Moore, S. R.; Franzen, M.; Benoit, P. H.; Sears, D. W. G.; Holley, A.; Myers, M.; Godsey, R.; Czlapinski, J.

    2003-01-01

    Chondrites are categorized into different groups by several properties, including the metal-to-silicate ratio. Various processes have been suggested to produce distinct metal/silicate ratios, some based on sorting in the early solar nebular and others occurring after accretion on the parent body. Huang et al. suggested that a weak gravitational field accompanied by degassing, could result in metal/silicate separation on parent bodies. We suggest that asteroids were volatile-rich, at least early in their histories. Spectroscopic evidence from asteroid surfaces indicates that one-third of all asteroids maybe rich in clays and hydrated minerals, similar to carbonaceous chondrites. Internal and/or external heating could have caused volatiles to evaporate and pass through a surface dust layer. Spacecraft images of asteroids show they have a thick regoliths. Housen, and Asphaug and Nolan proposed that even a 10 km diameter asteroid could potentially have a significant regolith. Grain size and grain density sorting could occur in the unconsolidated layer by the process known as fluidization. This process occurs when an upward stream of gas is passed through a bed of particles which are lifted against a gravitational force. Fluidization is commonly used commercially to sort particulates. This type of behavior is based upon the bed, as a whole, and differs from aerodynamic sorting. Two sets of reduced gravity experiments were conducted during parabolic flights aboard NASA's KC-135 aircraft. The first experiment employed 310 tubes of 2.5 cm diameter, containing mixtures of sand and metal grains. A gas source was used to fluidize the mixture at reduced gravity conditions and mixtures were analyzed after the flight. However, this experiment did not allow a description of the fluidization as a function of gravity. A second experiment was conducted on the KC-135 aircraft in the summer of 2001, consisting of two Plexiglas cylinders containing a metal/silicate mixture, and video

  6. Focus on the origin of matter

    NASA Astrophysics Data System (ADS)

    Di Bari, P.; Masiero, A.; Mohapatra, R.

    2013-03-01

    The origin of matter in the Universe is a fascinating cosmological puzzle that has triggered a formidable intellectual enterprise, started in 1967 with the prescient paper by Andrej Sakharov (1967 Pisma Zh. Eksp. Teor. Fiz. 5 32; 1967 JETP Lett. 52 4; 1991 Sov. Phys.—Usp. 34 392; 1991 Usp. Fiz. Nauk 161 61) aimed at relating a cosmological observation to the fundamental laws of physics, the goal of baryogenesis. A successful model of baryogenesis should ultimately identify the required source of charge parity violation and the origin of the cosmological matter-antimatter asymmetry. This focus issue is not only a review of the main ideas that have been proposed in baryogenesis but should also bear witness to the great vitality of the field and to show how future experimental results could bring a breakthrough in baryogenesis during the coming years. For this reason we selected, out of the multitude of proposed baryogenesis models, those that will more likely experience a significant experimental test during the coming years.

  7. In Situ Observation of Carbonaceous Material in the Matrices of CV and CM Carbonaceous Chondrites: Preliminary Results from Energy Filtered Transmission Electron Microscopy

    NASA Technical Reports Server (NTRS)

    Brearley, A. J.; Abreu, N. M.

    2001-01-01

    Energy filtered transmission electron microscopy shows that organic matter can be detected in situ in the matrices of carbonaceous chondrites at a spatial resolution of at least 1 nm. In CM chondrites, carbon is often associated with sulfide particles. Additional information is contained in the original extended abstract.

  8. In Situ Observation of Carbonaceous Material in the Matrices of CV and CM Carbonaceous Chondrites: Preliminary Results from Energy Filtered Transmission Electron Microscopy

    NASA Technical Reports Server (NTRS)

    Brearley, A. J.; Abreu, N. M.

    2001-01-01

    Energy filtered transmission electron microscopy shows that organic matter can be detected in situ in the matrices of carbonaceous chondrites at a spatial resolution of at least 1 nm. In CM chondrites, carbon is often associated with sulfide particles. Additional information is contained in the original extended abstract.

  9. Lunar and Planetary Science XXXV: Organics and Alteration in Carbonaceous Chondrites: Goop and Crud

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session "Organics and Alteration in Carbonaceous Chondrites: Goop and Crud" included the following reports:Organics on Fe-Silicate Grains: Potential Mimicry of Meteoritic Processes?; Molecular and Compound-Specific Isotopic Study of Monocarboxylic Acids in Murchison and Antarctic Meteorites; Nanoglobules, Macromolecular Materials, and Carbon Sulfides in Carbonaceous Chondrites; Evidence for Terrestrial Organic Contamination of the Tagish Lake Meteorite; Nitrogen Isotopic Imaging of Tagish Lake Carbon Globules; Microscale Distribution of Hydrogen Isotopes in Two Carbonaceous Chondrites; The Nature and Origin of Aromatic Organic Matter in the Tagish Lake Meteorite; Terrestrial Alteration of CM Chondritic Carbonate; Serpentine Nanotubes in CM Chondrites; Experimental Study of Serpentinization Reactions; Chondrule Glass Alteration in Type IIA Chondrules in the CR2 Chondrites EET 87770 and EET 92105: Insights into Elemental Exchange Between Chondrules and Matrices; Aqueous Alteration of Carbonaceous Chondrites: New Insights from Comparative Studies of Two Unbrecciated CM2 Chondrites, Y 791198 and ALH 81002 ;and A Unique Style of Alteration of Iron-Nickel Metal in WIS91600, an Unusual C2 Carbonaceous Chondrite.

  10. The Nature and Origin of Aromatic Organic Matter in the Tagish Lake Meteorite

    NASA Technical Reports Server (NTRS)

    Clemett, S. J.; Keller, L. P.; Nakamura, K.; McKay, D. S.

    2004-01-01

    The Tagish Lake meteorite is an unusual carbonaceous chondrite that does not fit well within existing chondrite taxonomy. Bulk analyses suggest approx. 5 wt.% C of which approx. 1 wt.% is in the form of organic matter and the remainder is present as inorganic carbonate. The exact nature and form of this organic component is, as is the case with the other ordinary and carbonaceous chondrites, still poorly understood. Yet its significance has far reaching implications, from contributing to the abiotic evolution of the early Earth and Mars, to providing geothermal constraints in the evolution of the Solar nebula.

  11. Origin of magnetite in oxidized CV chondrites: in situ measurement of oxygen isotope compositions of Allende magnetite and olivine

    NASA Technical Reports Server (NTRS)

    Choi, B. G.; McKeegan, K. D.; Leshin, L. A.; Wasson, J. T.

    1997-01-01

    Magnetite in the oxidized CV chondrite Allende mainly occurs as spherical nodules in porphyritic-olivine (PO) chondrules, where it is associated with Ni-rich metal and/or sulfides. To help constrain the origin of the magnetite, we measured oxygen isotopic compositions of magnetite and coexisting olivine grains in PO chondrules of Allende by an in situ ion microprobe technique. Five magnetite nodules form a relatively tight cluster in oxygen isotopic composition with delta 18O values from -4.8 to -7.1% and delta 17O values from -2.9 to -6.3%. Seven coexisting olivine grains have oxygen isotopic compositions from -0.9 to -6.3% in delta 18O and from -4.6 to -7.9% in delta 17O. The delta 17O values of the magnetite and coexisting olivine do not overlap; they range from -0.4 to -2.6%, and from -4.0 to -5.7%, respectively. Thus, the magnetite is not in isotopic equilibrium with the olivine in PO chondrules, implying that it formed after the chondrule formation. The delta 17O of the magnetite is somewhat more negative than estimates for the ambient solar nebula gas. We infer that the magnetite formed on the parent asteroid by oxidation of metal by H2O which had previously experienced minor O isotope exchange with fine-grained silicates.

  12. Fluid Inclusions in Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Saylor, J.; Zolensky, M. E.; Bodnar, R. J.; Le L.; Schwandt, C.

    2001-01-01

    Fluid inclusions are present in carbonaceous chondrites. Of the chondrites studied (CI1, CM1 and 2, CV3) fluid inclusions were found only in CM2s and CI1s, and by extrapolation are most likely to be found there in the future. Additional information is contained in the original extended abstract.

  13. Origin of spinel-rich chondrules and inclusions in carbonaceous and ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Kornacki, A. S.; Fegley, B., Jr.

    1984-01-01

    The evaluation of three models of the origin of spinel-rich chondrules and inclusions presented here includes new calculations of the major-element refractory mineral condensation sequence from a gas of solar composition over a wide pressure interval. Condensation calculations show that spinel-rich chondrules did not crystallize from metastable liquid condensates, and that spinel-rich inclusions are not aggregates of refractory nebular condensates. It is proposed that spinel-rich objects are fractionated distillation residues of small aggregates of primitive dust that lost Ca, Si-rich partial melts by evaporation, ablation, or splashing during collisions. This model also explains why spinel-rich chondrules and inclusions (1) are usually smaller than melilite-rich chondrules and inclusions; (2) often have highly fractionated trace-element compositions; and (3) usually do not contain Pt-metal nuggets even when they are more enriched in the Pt-group metals than nugget-bearing melilite-rich objects.

  14. The Aqueous Alteration of CR Chondrites: Experiments and Geochemical Modeling

    NASA Technical Reports Server (NTRS)

    Perronnet, M.; Berger, G.; Zolensky, M. E.; Toplis, M. J.; Kolb, V. M.; Bajagic, M.

    2007-01-01

    CR carbonaceous chondrites are of major interest since they contain some of the most primitive organic matter known. However, aqueous alteration has more or less overprinted their original features in a way that needs to be assessed. This study was initiated by comparing the mineralogy and modal abundances of the most altered CR1 chondrite, GRO 95577, to a less altered CR2. Calculated element distributions imply that GRO 95577 may result from aqueous alteration of Renazzo by an isochemical process on their parent asteroid, whose mineralogical composition was estimated ( Unaltered CR shown included table).

  15. The origin of organic matter in the Martian meteorite ALH84001.

    PubMed

    Becker, L; Popp, B; Rust, T; Bada, J L

    1999-03-30

    Stable carbon isotope measurements of the organic matter associated with the carbonate globules and the bulk matrix material in the ALH84001 Martian meteorite indicate that two distinct sources are present in the sample. The delta 13C values for the organic matter associated with the carbonate globules averaged -26% and is attributed to terrestrial contamination. In contrast, the delta 13C values for the organic matter associated with the bulk matrix material yielded a value of -15%. The only common sources of carbon on the Earth that yield similar delta 13C values, other then some diagenetically altered marine carbonates, are C4 plants. A delta 13C value of -15%, on the other hand, is consistent with a kerogen-like component, the most ubiquitous form of organic matter found in carbonaceous chondrites such as the Murchison meteorite. Examination of the carbonate globules and bulk matrix material using laser desorption mass spectrometry (LDMS) indicates the presence of a high molecular weight organic component which appears to be extraterrestrial in origin, possibly derived from the exogenous delivery, of meteoritic or cometary debris to the surface of Mars.

  16. Unified origin for baryonic visible matter and antibaryonic dark matter.

    PubMed

    Davoudiasl, Hooman; Morrissey, David E; Sigurdson, Kris; Tulin, Sean

    2010-11-19

    We present a novel mechanism for generating both the baryon and dark matter densities of the Universe. A new Dirac fermion X carrying a conserved baryon number charge couples to the standard model quarks as well as a GeV-scale hidden sector. CP-violating decays of X, produced nonthermally in low-temperature reheating, sequester antibaryon number in the hidden sector, thereby leaving a baryon excess in the visible sector. The antibaryonic hidden states are stable dark matter. A spectacular signature of this mechanism is the baryon-destroying inelastic scattering of dark matter that can annihilate baryons at appreciable rates relevant for nucleon decay searches.

  17. Lunar and Planetary Science XXXV: Concerning Chondrites

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The Lunar and Planetary Science XXXV session entitled "Concerning Chondrites" includes the following topics: 1) Petrology and Raman Spectroscopy of Shocked Phases in the Gujba CB Chondrite and the Shock History of the CB Parent Body; 2) The Relationship Between CK and CV Chondrites: A Single Parent Body Source? 3) Samples of Asteroid Surface Ponded Deposits in Chondritic Meteorites; 4) Composition and Origin of SiO2-rich Objects in Carbonaceous and Ordinary Chondrites; 5) Re-Os Systematics and HSE distribution in Tieschitz (H3.6); Two Isochrons for One Meteorite; 6) Loss of Chromium from Olivine During the Metamorphism of Chondrites; 7) Very Short Delivery Times of Meteorites After the L-Chondrite Parent Body Break-Up 480 Myr Ago; and 8) The Complex Exposure History of a Very Large L/LL5 Chondrite Shower: Queen Alexandra Range 90201.

  18. Hydrothermal origin of hexagonal CaAl2Si2O8 (dmisteinbergite) in a compact type A CAI from the Northwest Africa 2086 CV3 chondrite

    NASA Astrophysics Data System (ADS)

    Fintor, Krisztian; Park, Changkun; Nagy, Szabolcs; Pál-Molnár, Elemér; Krot, Alexander N.

    2014-05-01

    We report an occurrence of hexagonal CaAl2Si2O8 (dmisteinbergite) in a compact type A calcium-aluminum-rich inclusion (CAI) from the CV3 (Vigarano-like) carbonaceous chondrite Northwest Africa 2086. Dmisteinbergite occurs as approximately 10 μm long and few micrometer-thick lath-shaped crystal aggregates in altered parts of the CAI, and is associated with secondary nepheline, sodalite, Ti-poor Al-diopside, grossular, and Fe-rich spinel. Spinel is the only primary CAI mineral that retained its original O-isotope composition (Δ17O ~ -24‰); Δ17O values of melilite, perovskite, and Al,Ti-diopside range from -3 to -11‰, suggesting postcrystallization isotope exchange. Dmisteinbergite, anorthite, Ti-poor Al-diopside, and ferroan olivine have 16O-poor compositions (Δ17O ~ -3‰). We infer that dmisteinbergite, together with the other secondary minerals, formed by replacement of melilite as a result of fluid-assisted thermal metamorphism experienced by the CV chondrite parent asteroid. Based on the textural appearance of dmisteinbergite in NWA 2086 and petrographic observations of altered CAIs from the Allende meteorite, we suggest that dmisteinbergite is a common secondary mineral in CAIs from the oxidized Allende-like CV3 chondrites that has been previously misidentified as a secondary anorthite.

  19. Matter parity as the origin of scalar dark matter

    SciTech Connect

    Kadastik, Mario; Kannike, Kristjan; Raidal, Martti

    2010-01-01

    We extend the concept of matter parity P{sub M}=(-1){sup 3(B-L)} to nonsupersymmetric theories and argue that P{sub M} is the natural explanation to the existence of dark matter of the Universe. We show that the nonsupersymmetric dark matter must be contained in a scalar 16 representation(s) of SO(10), thus the unique low-energy dark matter candidates are P{sub M}-odd complex scalar singlet(s) S and an inert scalar doublet(s) H{sub 2}. We have calculated the thermal relic dark matter (DM) abundance of the model and shown that its minimal form may be testable at LHC via the standard model (SM) Higgs boson decays H{sub 1{yields}}DM DM. The PAMELA anomaly can be explained with the decays DM{yields}{nu}lW induced via seesawlike operator which is additionally suppressed by the Planck scale. Because the SM fermions are odd under matter parity too, the DM sector is just our scalar relative.

  20. On the possible origin of troilite-metal nodules in the Katol chondrite (L6-7)

    NASA Astrophysics Data System (ADS)

    Ray, Dwijesh; Ghosh, S.; Murty, S. V. S.

    2017-01-01

    Microtextural study of a single troilite-metal nodule (TMN) from the Katol L6-7 chondrite, a recent fall (May, 2012) in India suggests that the TMN is primarily an aggregate of submicron-scale intergrowth of troilite and kamacite (mean Ni: 6.18 wt%) juxtaposed with intensely fractured silicates, mainly olivine (Fa: 25 mole%), low-Ca pyroxene (Fs: 21.2 mole%), and a large volume of maskelynite. Evidence of shock textures in the TMN indicates a high degree of shock metamorphism that involves plagioclase-maskelynite and olivine-wadsleyite/ringwoodite transformations and formation of quenched metal-sulfide melt textures due to localized shear-induced frictional melting. It is inferred that the TMN formation is an independent, localized event by a high energy impact and its subsequent incorporation in the ejected chondritic fragment of the parent body. Katol chondrite has been calibrated with a peak shock pressure of S5 ( 45 GPa) after Stöffler et al. (1991), whereas peak shock pressure within the TMN exceeds the shock facies S6 (>45 GPa) following Bennett and McSween (1996) and Stöffler et al. (1991). Overall, the shock-thermal history of the Katol TMN is dissimilar as compared to the host chondrite.

  1. Local and exotic components of primitive meteorites, and their origin

    NASA Technical Reports Server (NTRS)

    Anders, E.

    1987-01-01

    The chemical and isotopic compositions of chondrites and their implications for chondrite origins are considered, reviewing the results of recent theoretical and experimental investigations. Numerical data are compiled in tables and graphs and discussed in detail. Consideration is given to the properties and classifications of chondrites; components of local origin in the matrix, chondrules, Ca-Al-rich inclusions, and carbon and organic matter; exotic components such as O-16-enriched dust, nucleosynthetic anomalies, and extinct radionuclides; and isotopic anomalies of volatiles such as C, N, and the noble gases. The implications of the chondrite data for the stony fraction of comet nuclei are briefly indicated.

  2. Mineralogy and possible origin of an unusual Cr-rich inclusion in the Los Martinez (L6) chondrite

    NASA Technical Reports Server (NTRS)

    Brearley, Adrian J.; Casanova, Ignacio; Miller, Mark L.; Keil, Klaus

    1991-01-01

    During a petrological study of the previously unclassified ordinary chondrite Los Martinez a highly unusual Cr-rich inclusion is found which is unique in both extraterrestrial and terrestrial mineralogy. Detailed SEM and TEM studies show that the inclusion consists of a highly zoned single crystal of plagioclase intergrown with chromium-rich spinel which indicates that it is the product of exsolution. The Cr-rich precursors of the inclusion probably have close affinities to the chronite-plagioclase chrondrules observed by Ramdohr (1967) in several ordinary chondrites. Based on the zoning in the inclusion it is suggested that it is the product of fractional crystallization from a melt, which may have formed as a liquid condensate, or by melting of solid condensates, in the solar nebula. Subsequent cooling of this melt condensate resulted in crystallization of the unidentified phase. After crystallization, the inclusion was probably incorporated into a parent body where it underwent metamorphism and was probably shocked to some degree. During this period of parent body metamorphism, exsolution and decomposition of the unknown precursor occurred to produce the observed intergrowth of plagioclase and chromite. Los Martinez is classified as an L6 ordinary chondrite breccia.

  3. Mineralogy and possible origin of an unusual Cr-rich inclusion in the Los Martinez (L6) chondrite

    NASA Technical Reports Server (NTRS)

    Brearley, Adrian J.; Casanova, Ignacio; Miller, Mark L.; Keil, Klaus

    1991-01-01

    During a petrological study of the previously unclassified ordinary chondrite Los Martinez a highly unusual Cr-rich inclusion is found which is unique in both extraterrestrial and terrestrial mineralogy. Detailed SEM and TEM studies show that the inclusion consists of a highly zoned single crystal of plagioclase intergrown with chromium-rich spinel which indicates that it is the product of exsolution. The Cr-rich precursors of the inclusion probably have close affinities to the chronite-plagioclase chrondrules observed by Ramdohr (1967) in several ordinary chondrites. Based on the zoning in the inclusion it is suggested that it is the product of fractional crystallization from a melt, which may have formed as a liquid condensate, or by melting of solid condensates, in the solar nebula. Subsequent cooling of this melt condensate resulted in crystallization of the unidentified phase. After crystallization, the inclusion was probably incorporated into a parent body where it underwent metamorphism and was probably shocked to some degree. During this period of parent body metamorphism, exsolution and decomposition of the unknown precursor occurred to produce the observed intergrowth of plagioclase and chromite. Los Martinez is classified as an L6 ordinary chondrite breccia.

  4. Recognition in Ants: Social Origin Matters

    PubMed Central

    Meunier, Joël; Delémont, Olivier; Lucas, Christophe

    2011-01-01

    The ability of group members to discriminate against foreigners is a keystone in the evolution of sociality. In social insects, colony social structure (number of queens) is generally thought to influence abilities of resident workers to discriminate between nestmates and non-nestmates. However, whether social origin of introduced individuals has an effect on their acceptance in conspecific colonies remains poorly explored. Using egg-acceptance bioassays, we tested the influence of social origin of queen-laid eggs on their acceptance by foreign workers in the ant Formica selysi. We showed that workers from both single- and multiple-queen colonies discriminated against foreign eggs from single-queen colonies, whereas they surprisingly accepted foreign eggs from multiple-queen colonies. Chemical analyses then demonstrated that social origins of eggs and workers could be discriminated on the basis of their chemical profiles, a signal generally involved in nestmate discrimination. These findings provide the first evidence in social insects that social origins of eggs interfere with nestmate discrimination and are encoded by chemical signatures. PMID:21573235

  5. Paleomagnetism of enstatite chondrites

    NASA Astrophysics Data System (ADS)

    Feng, H.; Weiss, B. P.; Tikoo, S. M.; Gattacceca, J.; Suavet, C. R.; Andrade Lima, E.

    2013-12-01

    Chondritic meteorites are widely thought to have originated on unmelted parent bodies. However, recent studies of CV carbonaceous chondrites have observed stable remanent magnetization acquired after accretion that may have been imparted by a core dynamo on the parent body. This suggests that CV chondrites may have originated from an internally melted, partially differentiated parent body with a relic chondritic crust. Although diverging from the predominant view that chondrites are samples of unmelted bodies, this idea has deep roots in the history of meteoritics. In particular, a common parent body has often been invoked for enstatite chondrites and enstatite achondrites (aubrites), which share many compositional, mineralogical, and isotopic similarities. Therefore, enstatite chondrites are a natural target for further testing the partial differentiation hypothesis. However, there are very few previous paleomagnetic studies of these meteorites. To address this, we studied the magnetic properties and paleomagnetism of three enstatite chondrites (Pillistfer EL6, Eagle EL6, and Sahara 97158 EH3) to examine the feasibility of dynamo generation on the enstatite chondrite parent body. In Pillistfer, our alternating field (AF) demagnetization of mutually oriented interior and fusion-crusted subsamples revealed three low coercivity components blocked from ~1.5-2.5 mT (component A1), ~2.5-7 mT (component A2), and ~7-9 mT (component A3). The A2 and A3 components are poorly defined, likely due to spurious anhysteretic remanent magnetization (ARM) acquired during AF demagnetization. Thermal demagnetization revealed low temperature (T1) and medium temperature (T2) components, ranging from 50-600°C and 600-700°C, respectively. The A1 and T1 components coincided, while the A2 and T2 components were more scattered (although nonrandomly distributed). Components A1 and A2 of fusion-crusted samples were similarly oriented to those of interior samples. The ratio of natural

  6. P-O-rich sulfide phase in CM chondrites: Constraints on its origin on the CM parent body

    NASA Astrophysics Data System (ADS)

    Zhang, Ai-Cheng; Itoh, Shoichi; Yurimoto, Hisayoshi; Hsu, Wei-Biao; Wang, Ru-Cheng; Taylor, Lawrence A.

    2016-01-01

    CM chondrites are a group of primitive meteorites that have recorded the alteration history of the early solar system. We report the occurrence, chemistry, and oxygen isotopic compositions of P-O-rich sulfide phase in two CM chondrites (Grove Mountains [GRV] 021536 and Murchison). This P-O-rich sulfide is a polycrystalline aggregate of nanometer-size grains. It occurs as isolated particles or aggregates in both CM chondrites. These grains, in the matrix and in type-I chondrules from Murchison, were partially altered into tochilinite; however, grains enclosed by Ca-carbonate are much less altered. This P-O-rich sulfide in Murchison is closely associated with magnetite, FeNi phosphide, brezinaite (Cr3S4), and eskolaite (Cr2O3). In addition to sulfur as the major component, this sulfide contains ~6.3 wt% O, ~5.4 wt% P, and minor amounts of hydrogen. Analyses of oxygen isotopes by SIMS resulted in an average δ18O value of -22.5 ‰ and an average Δ17O value of 0.2 ± 9.2 ‰ (2σ). Limited variations in both chemical compositions and electron-diffraction patterns imply that the P-O-rich sulfide may be a single phase rather than a polyphase mixture. Several features indicate that this P-O-rich sulfide phase formed at low temperature on the parent body, most likely through the alteration of FeNi metal (a) close association with other low-temperature alteration products, (b) the presence of hydrogen, (c) high Δ17O values and the presence in altered mesostasis of type-I chondrules and absence in type-II chondrules. The textural relations of the P-O-rich sulfide and other low-temperature minerals reveal at least three episodic-alteration events on the parent body of CM chondrites (1) formation of P-O-rich sulfide during sulfur-rich aqueous alteration of P-rich FeNi metal, (2) formation of Ca-carbonate during local carbonation, and (3) alteration of P-O-rich sulfide and formation of tochilinite during a period of late-stage intensive aqueous alteration.

  7. Organic analysis of the Antarctic carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Kotra, R. K.; Shimoyama, A.; Ponnamperuma, C.; Hare, P. E.; Yanai, K.

    1981-01-01

    Thus far, organic analysis of carbonaceous chondrites has proven the only fruitful means of examining complex organic matter of extraterrestrial origin. The present paper presents the results of organic analysis of two Antarctic meteorites, Allan Hills (77306) and Yamato (74662), which may be considered free from terrestrial contamination. Ion-exchange chromatography, gas chromatography and mass spectrometery of meteorite samples reveal the presence in Yamato of 15 and in Allan Hills of 20 protein and nonprotein amino acids, the most abundant of which are glycine and alanine. Abundances of the D and L enantiomers of each amino acid are also found to be nearly equal. Data thus indicate an abiotic extraterrestrial origin for the matter, and confirm a lack of terrestrial contamination.

  8. Peritoneal mesothelioma: the site of origin matters.

    PubMed

    Kindler, Hedy Lee

    2013-01-01

    The etiology, gender distribution, pathology, natural history, and treatment options for mesothelioma (MM) differ substantially depending on the site of origin. Peritoneal mesothelioma (MPeM) is a rare disease, comprising only approximately 10% to 15% of the 2,500 cases of MM diagnosed in the United States each year. Patients with MPeM are younger than patients with pleural MM, and a higher proportion, mostly women, are long-term survivors. Most MPeM is caused by asbestos exposure. Germ-line mutations of BAP1 (BRCA associated protein 1) can predispose to MM, uveal melanoma, and potentially other cancers. MPeM can be challenging to diagnose, and cytology is rarely helpful. Review by an experienced pathologist using a panel of at least two positive and two negative immunohistochemical stains is essential. The three major pathologic subtypes are epithelial, sarcomatoid, and biphasic. Most cases are epithelial; the others have a dismal prognosis. Two indolent subtypes of borderline malignant potential-well-differentiated papillary mesothelioma and benign multicystic mesothelioma-are more common in the peritoneum and are treated surgically. In highly selected patients receiving treatment at experienced referral centers, an aggressive locoregional strategy that combines cytoreductive surgery to remove all gross disease and hyperthermic intraperitoneal chemotherapy to treat residual microscopic tumors yields a 3-year survival of 60% and a median survival approaching 5 years, far better than expected from historic controls. This approach also provides durable palliation of malignant ascites in nearly all patients. Pemetrexed is the only U.S. Food and Drug Administration (FDA)-approved systemic chemotherapy for pleural MM. Largely on the basis of data from pharmaceutical registry studies, the activity of pemetrexed-based chemotherapy appears to be similar in pleural MM and MPeM.

  9. The trace element chemistry of CaS in enstatite chondrites and some implications regarding its origin

    NASA Technical Reports Server (NTRS)

    Larimer, John W.; Ganapathy, R.

    1987-01-01

    The trace element distribution in oldhamite (CaS) extracted from enstatite chondrites was determined by INAA. Prior to extraction, the petrologic setting of the grains was studied microscopically, and their minor element contents determined by microprobe analysis; samples that displayed a wide range of minor element contents were selected for detailed elementary analysis. Those samples of CaS suspected to be more primitive on the basis of their minor element and petrologic siting contain the entire inventory of the host meteorite's light REE (LREE) and Eu, plus 30-50 percent of the heavy-REE inventory. In less primitive samples, the LREE are less enriched although Eu remains highly concentrated. Several other elements, including lithophiles and chalcophiles, are most enriched in the most primitive CaS. It is suggested that oldhamite played a key role in the redistribution of these elements during the metamorphism and evolution of enstatite-rich material.

  10. Early Archean Spherule Beds: Chromium Isotopes Confirm Origin Through Multiple Impacts of Projectiles of Carbonaceous Chondrite Type

    NASA Technical Reports Server (NTRS)

    Kyte, Frank T.; Shukolyukov, Alex; Lugmair, Guenter W.; Lowe, Donald R.; Byerly, Gary R.

    2003-01-01

    Three Early Archean spherule beds from Barberton, South Africa, have anomalous Cr isotope compositions in addition to large Ir anomalies, confirming the presence of meteoritic material with a composition similar to that in carbonaceous chondrites. The extra-terrestrial components in beds S2, S3, and S4 are estimated to be approx. l%, 50% - 60%, and 15% - 30%, respectively. These beds are probably the distal, and possibly global, ejecta from major large-body impacts. These impacts were probably much larger than the Cretaceous-Tertiary event, and all occurred over an interval of approx. 20 m.y., implying an impactor flux at 3.2 Ga that was more than an order of magnitude greater than the present flux.

  11. Early Archean Spherule Beds: Chromium Isotopes Confirm Origin Through Multiple Impacts of Projectiles of Carbonaceous Chondrite Type

    NASA Technical Reports Server (NTRS)

    Kyte, Frank T.; Shukolyukov, Alex; Lugmair, Guenter W.; Lowe, Donald R.; Byerly, Gary R.

    2003-01-01

    Three Early Archean spherule beds from Barberton, South Africa, have anomalous Cr isotope compositions in addition to large Ir anomalies, confirming the presence of meteoritic material with a composition similar to that in carbonaceous chondrites. The extra-terrestrial components in beds S2, S3, and S4 are estimated to be approx. l%, 50% - 60%, and 15% - 30%, respectively. These beds are probably the distal, and possibly global, ejecta from major large-body impacts. These impacts were probably much larger than the Cretaceous-Tertiary event, and all occurred over an interval of approx. 20 m.y., implying an impactor flux at 3.2 Ga that was more than an order of magnitude greater than the present flux.

  12. Sediment extracted organic matter fluorescence: an archive of organic matter flux and origins?

    NASA Astrophysics Data System (ADS)

    Stedmon, C. A.; Funkey, C. P.; Conley, D. J.

    2016-02-01

    Organic matter buried in sediments contain a record of the intensity and characteristics of organic matter supply from overlying waters through time. A fraction of the organic matter pool can be extracted and characterised using UV-visible spectroscopy (absorption and fluorescence). In this study we investigate the utility of using the optical characteristics of this organic matter pool as a quantitative and qualitative proxy. We use the optical properties of based extracted organic matter from a well characterised Baltic Sea core from the Northern Gotland Deep to infer changes in the intensity and character of organic matter supply over the past 8000 years. Over this period the modern Baltic Sea was formed from its original state as the Ancylus Lake. There are three clear periods of hypoxia which have influenced the supply and quality of organic matter in sediments. The first two periods, the Ancylus-Littorina transgression (7000-4000 B.P.) and Medieval Climate Anomaly (1400-700 years B.P.) are attributed to enhanced stratification. The third is recognised as driven by anthropogenic eutrophication over the past 100 years. The optical properties of sediment extracted organic matter from these periods not only follow the trends in sediment organic carbon content but also show clear differences organic matter characteristics not apparent in other measurements. The series of hypoxic events within the Ancylus-Littorina transgression differ from each other. While organic matter from 7000-6500 years BP is similar to that from MCA and modern times, subsequent Ancylus-Littorina transgression periods of hypoxia are different suggesting different origins of organic matter. Organic matter optical characteristics here are more similar to material from periods will less/no hypoxia.

  13. Origin of EL3 chondrites: Evidence for variable C/O ratios during their course of formation—A state of the art scrutiny

    NASA Astrophysics Data System (ADS)

    El Goresy, A.; Lin, Y.; Miyahara, M.; Gannoun, A.; Boyet, M.; Ohtani, E.; Gillet, P.; Trieloff, M.; Simionovici, A.; Feng, L.; Lemelle, L.

    2017-05-01

    Mineral inventories of enstatite chondrites; (EH and EL) are strictly dictated by combined parameters mainly very low dual oxygen (fO2) and sulfur (fS2) fugacities. They are best preserved in the Almahata Sitta MS-17, MS-177 fragments, and the ALHA 77295 and MAC 88136 Antarctic meteorites. These conditions induce a stark change of the geochemical behavior of nominally lithophile elements to chalcophile or even siderophile and changes in the elemental partitioning thus leading to formation of unusual mineral assemblages with high abundance of exotic sulfide species and enrichment in the metallic alloys, for example, silicides and phosphides. Origin and mode of formation of these exotic chondrites, and their parental source regions could be best scrutinized by multitask research experiments of the most primitive members covering mineralogical, petrological, cosmochemical, and indispensably short-lived isotopic chronology. The magnitude of temperature and pressure prevailed during their formation in their source regions could eventually be reasonably estimated: pre- and postaccretionary could eventually be deduced. The dual low fugacities are regulated by the carbon to oxygen ratios estimated to be >0.83 and <1.03. These parameters not only induce unusual geochemical behavior of the elements inverting many nominally lithophile elements to chalcophile or even siderophile or anthracophile. Structure and mineral inventories in EL3 and EH3 chondrites are fundamentally different. Yet EH3 and EL3 members store crucial information relevant to eventual source regions and importantly possible variation in C/O ratio in the course of their evolution. EL3 and EH3 chondrites contain trichotomous lithologies (1) chondrules and their fragments, (2) polygonal enstatite-dominated objects, and (3) multiphase metal-rich nodules. Mineralogical and cosmochemical inventories of lithologies in the same EL3 indicate not only similarities (REE inventory and anomalies in oldhamite) but also

  14. Hydrothermal alteration experiments: tracking the path from interstellar to chondrites organics

    NASA Astrophysics Data System (ADS)

    Vinogradoff, V.; Bernard, S.; Le Guillou, C.; Jaber, M.; Remusat, L.

    2015-10-01

    Organic molecules are detected in primitive carbonaceous chondrites. The origin of these organics, whether formed prior the accretion phase, or in-situ on the parent body, is still a matter of debate. We have investigated experimentally the chemical evolution of interstellar organic molecules submitted to hydrothermal conditions, mimicking asteroidal alteration (T<200°C). In particular, we want to assess the potential catalytic role of clays minerals in the polymerization/degradation of organics. Hexamethylenetetramine (HMT, compound of C-N bonds) is used as a plausible interstellar precursors from icy grains. Experimental products reveal a large diversity of molecules, including nitrogen organic molecules similar to those found in chondrites.

  15. Deuterium in carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Kolodny, Y.; Kerridge, J. F.; Kaplan, I. R.

    1980-01-01

    Hydrogen isotopic compositions in seven carbonaceous chondrites lie in the range -70 to +771 per thousand relative to standard mean ocean water. These values decrease, to a range from -145 to +219 per thousand, after low-temperature oxidation in an oxygen plasma. Deuterium enrichment is therefore concentrated in the organic matter, the hydrous silicates probably lying close to the terrestrial range for such material. Calculated values for delta D of the organic fraction are +450 per thousand for Orgueil and Ivuna and up to +1600 per thousand for Renazzo. These enrichments, at least for Orgueil and Ivuna, suggest equilibration with protosolar hydrogen at very low temperatures. Assuming a value of 2.5 x 10 to the -5th for the protosolar D/H ratio, nominal equilibration temperatures of 230 K for silicates and 180 K for organic matter may be derived.

  16. C Chondrite Clasts in H Chondrite Regolith Breccias: Something Different

    NASA Technical Reports Server (NTRS)

    Zolensky, M. E.; Fries, M.; Utas, J.; Chan, Q. H.-S.; Kebukawa, Y.; Steele, A.; Bodnar, R. J.; Ito, M.; Nakashima, D.; Greenwood, R.; Rahman, Z.; Le, L.; Ross, D. K.

    2016-01-01

    Zag (H3-6) and Monahans (1998) (H5) are regolith breccias that contain 4.5 GY old halite crystals which in turn contain abundant inclusions of aqueous fluids, solids and organics [1-4]. We have previously proposed that these halites originated on a hydro-volcanically-active C-class asteroid, probably Ceres [3-7]. We have begun a detailed analysis of the included solids and organics and are re-examining the related carbonaceous (C)) chondrite clast we previously reported in Zag [5-7]. These new investigations will potentially reveal the mineralogy of asteroid Ceres. We report here on potentially identical C chondrite clasts in the H chondrite regolith breccias Tsukuba (H5-6) and Carancas (H4-5). The clast in Tsukuba was known before [8], but the Carancas clast is newly recognized.

  17. Lung bioaccessibility of contaminants in particulate matter of geological origin.

    PubMed

    Guney, Mert; Chapuis, Robert P; Zagury, Gerald J

    2016-12-01

    Human exposure to particulate matter (PM) has been associated with adverse health effects. While inhalation exposure to airborne PM is a prominent research subject, exposure to PM of geological origin (i.e., generated from soil/soil-like material) has received less attention. This review discusses the contaminants in PM of geological origin and their relevance for human exposure and then evaluates lung bioaccessibility assessment methods and their use. PM of geological origin can contain toxic elements as well as organic contaminants. Observed/predicted PM lung clearance times are long, which may lead to prolonged contact with lung environment. Thus, certain exposure scenarios warrant the use of in vitro bioaccessibility testing to predict lung bioavailability. Limited research is available on lung bioaccessibility test development and test application to PM of geological origin. For in vitro tests, test parameter variation between different studies and concerns about physiological relevance indicate a crucial need for test method standardization and comparison with relevant animal data. Research is recommended on (1) developing robust in vitro lung bioaccessibility methods, (2) assessing bioaccessibility of various contaminants (especially polycyclic aromatic hydrocarbons (PAHs)) in PM of diverse origin (surface soils, mine tailings, etc.), and (3) risk characterization to determine relative importance of exposure to PM of geological origin.

  18. Serpentine Nanotubes in CM Chondrites

    NASA Technical Reports Server (NTRS)

    Zega, Thomas J.; Garvie, Laurence A. J.; Dodony, Istvan; Buseck, Peter R.

    2004-01-01

    The CM chondrites are primitive meteorites that formed during the early solar system. Although they retain much of their original physical character, their matrices and fine-grained rims (FGRs) sustained aqueous alteration early in their histories [1- 3]. Serpentine-group minerals are abundant products of such alteration, and information regarding their structures, compositions, and spatial relationships is important for determining the reactions that produced them and the conditions under which they formed. Our recent work on FGRs and matrices of the CM chondrites has revealed new information on the structures and compositions of serpentine-group minerals [4,5] and has provided insights into the evolution of these primitive meteorites. Here we report on serpentine nanotubes from the Mighei and Murchison CM chondrites [6].

  19. Origin of the eclogitic clasts with graphite-bearing and graphite-free lithologies in the Northwest Africa 801 (CR2) chondrite: Possible origin from a Moon-sized planetary body inferred from chemistry, oxygen isotopes and REE abundances

    NASA Astrophysics Data System (ADS)

    Hiyagon, H.; Sugiura, N.; Kita, N. T.; Kimura, M.; Morishita, Y.; Takehana, Y.

    2016-08-01

    In order to clarify the origin of the eclogitic clasts found in the NWA801 (CR2) chondrite (Kimura et al., 2013), especially, that of the high pressure and temperature (P-T) condition (∼3 GPa and ∼1000 °C), we conducted ion microprobe analyses of oxygen isotopes and rare earth element (REE) abundances in the clasts. Oxygen isotopic compositions of the graphite-bearing lithology (GBL) and graphite-free lithology (GFL) show a slope ∼0.6 correlation slightly below the CR-CH-CB chondrites field in the O three-isotope-diagram, with a large variation for the former and almost homogeneous composition for the latter. The average REE abundances of the two lithologies show almost unfractionated patterns. Based on these newly obtained data, as well as mineralogical observations, bulk chemistry, and considerations about diffusion timescales for various elements, we discuss in detail the formation history of the clasts. Consistency of the geothermobarometers used by Kimura et al. (2013), suggesting equilibration of various elements among different mineral pairs, provides a strong constraint for the duration of the high P-T condition. We suggest that the high P-T condition lasted 102-103 years. This clearly precludes a shock high pressure (HP) model, and hence, strongly supports a static HP model. A static HP model requires a Moon-sized planetary body of ∼1500 km in radius. Furthermore, it implies two successive violent collisions, first at the formation of the large planetary body, when the clasts were placed its deep interior, and second, at the disruption of the large planetary body, when the clasts were expelled out of the parent body and later on transported to the accretion region of the CR chondrites. We also discuss possible origin of O isotopic variations in GBL, and presence/absence of graphite in GBL/GFL, respectively, in relation to smelting possibly occurred during the igneous process(es) which formed the two lithologies. Finally we present a possible

  20. Aqueous Alteration of Enstatite Chondrites

    NASA Technical Reports Server (NTRS)

    Zolensky, M. E.; Ziegler, K.; Weisberg, M. K.; Gounelle, M.; Berger, E. L.; Le, L.; Ivanov, A.

    2014-01-01

    The Kaidun meteorite is different from all other meteorites [1], consisting largely of a mixture of “incompatible” types of meteoritic material – carbonaceous and enstatite chondrites, i.e. corre-sponding to the most oxidized and the most reduced samples of meteorite materials, including CI1, CM1-2, CV3, EH3-5, and EL3. In addition to these, minor amounts of ordinary and R chondrites are present. In addition, approximately half of the Kaidun lithologies are new materials not known as separate meteorites. Among these are aqueously altered enstatite chondrites [1], which are of considerable interest because they testify that not all reduced asteroids escaped late-stage oxidation, and hydrolysis, and also because hydrated poorly crystalline Si-Fe phase, which in turn is re-placed by serpentine (Figs 3-5). In the end the only indication of the original presence of metal is the re-sidual carbides. In other enstatite chondrite lithogies (of uncertain type) original silicates and metal have been thoroughly replaced by an assemblage of authi-genic plagioclase laths, calcite boxwork, and occasion-al residual grains of silica, Cr-rich troilite, ilmenite, and rare sulfides including heideite (Fig. 6). Fe and S have been largely leached from the rock (Fig. 4). Again the accessory phases are the first clue to the original character of the rock, which can be verified by O isotopes. It is fortunate that Kaidun displays every step of the alteration process.

  1. I-129/I-127 variations among enstatite chondrites

    NASA Technical Reports Server (NTRS)

    Kennedy, B. M.; Hudson, B.; Hohenberg, C. M.; Podosek, F. A.

    1988-01-01

    The iodine isotopic compositions and corresponding I-Xe ages were obtained for eight enstatite chondrites, bringing the total number of enstatite chondrites examined by the I-Xe technique to 11. Iodine isotopic compositions of these 11 chondrites indicate a well-defined hiatus correlated with the hiatus in chemical composition defining the two distinct enstatite groups: EH(4,5) and EL(6). Judging by the I-129/I-127 ratios and assuming that both the EH and EL groups originated from a reservoir with a uniform initial iodine isotopic composition, the EH(4,5) chondrites were estimated to be about 4 mln older than the El chondrites.

  2. Formation of replicating saponite from a gel in the presence of oxalate: implications for the formation of clay minerals in carbonaceous chondrites and the origin of life

    USGS Publications Warehouse

    Schumann, Dirk; Hartman, Hyman; Eberl, Dennis D.; Sears, S. Kelly; Hesse, Reinhard; Vali, Hojatollah

    2012-01-01

    The potential role of clay minerals in the abiotic origin of life has been the subject of ongoing debate for the past several decades. At issue are the clay minerals found in a class of meteorites known as carbonaceous chondrites. These clay minerals are the product of aqueous alteration of anhydrous mineral phases, such as olivine and orthopyroxene, that are often present in the chondrules. Moreover, there is a strong correlation in the occurrence of clay minerals and the presence of polar organic molecules. It has been shown in laboratory experiments at low temperature and ambient pressure that polar organic molecules, such as the oxalate found in meteorites, can catalyze the crystallization of clay minerals. In this study, we show that oxalate is a robust catalyst in the crystallization of saponite, an Al- and Mg-rich, trioctahedral 2:1 layer silicate, from a silicate gel at 60°C and ambient pressure. High-resolution transmission electron microscopy analysis of the saponite treated with octadecylammonium (n(C)=18) cations revealed the presence of 2:1 layer structures that have variable interlayer charge. The crystallization of these differently charged 2:1 layer silicates most likely occurred independently. The fact that 2:1 layer silicates with variable charge formed in the same gel has implications for our understanding of the origin of life, as these 2:1 clay minerals most likely replicate by a mechanism of template-catalyzed polymerization and transmit the charge distribution from layer to layer. If polar organic molecules like oxalate can catalyze the formation of clay-mineral crystals, which in turn promote clay microenvironments and provide abundant adsorption sites for other organic molecules present in solution, the interaction among these adsorbed molecules could lead to the polymerization of more complex organic molecules like RNA from nucleotides on early Earth.

  3. Formation of replicating saponite from a gel in the presence of oxalate: implications for the formation of clay minerals in carbonaceous chondrites and the origin of life.

    PubMed

    Schumann, Dirk; Hartman, Hyman; Eberl, Dennis D; Sears, S Kelly; Hesse, Reinhard; Vali, Hojatollah

    2012-06-01

    The potential role of clay minerals in the abiotic origin of life has been the subject of ongoing debate for the past several decades. At issue are the clay minerals found in a class of meteorites known as carbonaceous chondrites. These clay minerals are the product of aqueous alteration of anhydrous mineral phases, such as olivine and orthopyroxene, that are often present in the chondrules. Moreover, there is a strong correlation in the occurrence of clay minerals and the presence of polar organic molecules. It has been shown in laboratory experiments at low temperature and ambient pressure that polar organic molecules, such as the oxalate found in meteorites, can catalyze the crystallization of clay minerals. In this study, we show that oxalate is a robust catalyst in the crystallization of saponite, an Al- and Mg-rich, trioctahedral 2:1 layer silicate, from a silicate gel at 60°C and ambient pressure. High-resolution transmission electron microscopy analysis of the saponite treated with octadecylammonium (n(C)=18) cations revealed the presence of 2:1 layer structures that have variable interlayer charge. The crystallization of these differently charged 2:1 layer silicates most likely occurred independently. The fact that 2:1 layer silicates with variable charge formed in the same gel has implications for our understanding of the origin of life, as these 2:1 clay minerals most likely replicate by a mechanism of template-catalyzed polymerization and transmit the charge distribution from layer to layer. If polar organic molecules like oxalate can catalyze the formation of clay-mineral crystals, which in turn promote clay microenvironments and provide abundant adsorption sites for other organic molecules present in solution, the interaction among these adsorbed molecules could lead to the polymerization of more complex organic molecules like RNA from nucleotides on early Earth.

  4. Establishing the origin of particulate matter across Europe

    NASA Astrophysics Data System (ADS)

    Schaap, Martijn; Kranenburg, Richard; Hendriks, Carlijn; Kuenen, Jeroen

    2016-04-01

    Exposure to particulate matter (PM) in ambient air leads to adverse health effects. To design cost effective mitigation strategies, a thorough understanding of the sources of particulate matter is crucial. In this paper we like to provide an overview of recent source apportionment studies aimed at PM and its precursors carried out at TNO. The source apportionment module that tracks the origin of modelled particulate matter distributions throughout a LOTOS-EUROS simulation will be explained. To optimally apply this technology dedicated emission inventories, e.g. fuel type specific, need to be generated. Applications to Europe shows that in northwestern Europe the contribution of transport and agricultural emissions dominate the PM mass concentrations, especially during episodic events. In eastern Europe, the domestic and energy sector are much more important. In southern Europe the picture is more mixed, although the frequent high levels of desert dust stand out. Evaluation of the source allocation against experimental data and PMF analyses is challenging as there is only a limited availability of source specific tracers or factors that can be used for direct comparison. Nonetheless, for the available tracers such as vanadium for heavy fuel oil combustion an evaluation is very well possible. The source apportionment technique can also be used to interpret particulate matter formation efficiencies. It will be shown that the conversion rates for the secondary inorganic aerosol precursors (NOx, NH3 and SO2) have changed during the last 20 years. A particular problem is related to the fact that CTMs systematically underestimate observed PM levels, which means that the contribution of certain source categories (natural, agriculture, combustion) are underestimated. Future developments needed to improve the source apportionment information concerning process knowledge, data assimilation as well as model implementation will be discussed. Specific challenges concerning the

  5. Oxidation state in chondrites

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.; Fegley, Bruce; Brett, Robin

    1988-01-01

    An evaluation is made of extant data on chondrite oxidation states and intrinsic O fugacities. A variety of oxidation states are exhibited by the chondritic meteorites; petrologic and chemical data may be used to arrange the major chondrite groups in order of oxidation state. The intrinsic O fugacity measurements on chondrite whole-rock samples are noted to display a corresponding ordering of oxidation states. Metamorphosed chondrites and igneous meteorites that were substantially altered by metamorphic reactions, outgassing, and igneous processes may preserve information on the oxidation state and size of their parent bodies.

  6. Condensed Matter Lessons About the Origin of Time

    NASA Astrophysics Data System (ADS)

    Jannes, Gil

    2015-03-01

    It is widely hoped that quantum gravity will shed light on the question of the origin of time in physics. The currently dominant approaches to a candidate quantum theory of gravity have naturally evolved from general relativity, on the one hand, and from particle physics, on the other hand. A third important branch of twentieth century `fundamental' physics, condensed-matter physics, also offers an interesting perspective on quantum gravity, and thereby on the problem of time. The bottomline might sound disappointing: to understand the origin of time, much more experimental input is needed than what is available today. Moreover it is far from obvious that we will ever find out the true origin of physical time, even if we become able to directly probe physics at the Planck scale. But we might learn some interesting lessons about time and the structure of our universe in the process. A first lesson is that there are probably several characteristic scales associated with "quantum gravity" effects, rather than the single Planck scale usually considered. These can differ by several orders of magnitude, and thereby conspire to hide certain effects expected from quantum gravity, rendering them undetectable even with Planck-scale experiments. A more tentative conclusion is that the hierarchy between general relativity, special relativity and Newtonian physics, usually taken for granted, might have to be interpreted with caution.

  7. Origin of sedimentary organic matter at the Northern Cascadia Margin

    NASA Astrophysics Data System (ADS)

    Kaneko, M.; Naraoka, H.

    2007-12-01

    Gas hydrate in marine sediments may have important roles on global carbon cycle and climatic change. We examined origins of sedimentary organic matter and bacterial activity in deep and hydrate-bearing sediment cored in Site U1327 and U1328 at northern Cascadia Margin by IODP Exp311, using σ13C of total organic carbon (TOC), σ15N of total nitrogen (TN), σ34S of total sulfur (TS), and σ13C of biomarkers in hydrocarbon fraction. In both sites, TOC/TN ratios and σ13C of TOC values ranged from 5.5 to 18.0 and -25.7 to -21.5 ‰, respectively, suggesting that sedimentary organic matter is a mixture of terrestrial and marine sources. Long chain (n)-alkanes (C27, C29, and C30), known as biomarkers of terrestrial higher plant were most abundant components (up to ~50 μg/gCorg) through down to 300 mbsf, and their σ13C values (-34.3 to -28.7 ‰) reveal their C3 plant origin. In addition, very long-chain alkene (C37) occurred in some sediments, which suggests the blooming by coccolithophore in the past. σ34S of TS values at both sites show large variation between -30 to +20 ‰. Most of σ34S of TS values were less than present σ34S value of seawater sulfate (+20.3 ‰). This is attributable to isotope fractionation during microbial sulfate reduction. Crocetenes including one double bond occurred in deep sediments with higher σ13C values (-23 ‰) than the reported σ13C values (< ~ -100 ‰, Elvert et al, 2000), providing possibility of heterotrophic archaea using marine organic matter as a carbon source. Pentamethylicosane (PMI) was detected in relatively high concentrations at 249 mbsf at Site U1328 and its σ13C value was -46.4 ‰. This PMI could be chemoautotrophic archaea in origin such as methanogen. Diploptene was also detected in most sediments with the σ13C value of -37 to -35 ‰, probably being characteristic of chemoautotrophic bacteria.

  8. Mineralogy and defect microstructure of an olivine-dominated Itokawa dust particle: evidence for shock metamorphism, collisional fragmentation, and LL chondrite origin

    NASA Astrophysics Data System (ADS)

    Langenhorst, Falko; Harries, Dennis; Pollok, Kilian; van Aken, Peter A.

    2014-12-01

    We report here detailed analytical scanning and transmission electron microscopic investigations on an olivine-dominated dust particle (RB-QD04-0042) from the surface of asteroid 25143 Itokawa. The dust particle was returned to Earth by the Hayabusa spacecraft and was made available in the context of the first announcement of opportunity for Hayabusa sample investigation. Multiple thin slices were prepared from the precious particle by means of focused ion beam thinning, providing a unique three-dimensional access to its interior. The 40 × 50 μm sized olivine particle contains a spherical diopside inclusion and an intimate intergrowth of troilite and tetrataenite. The compositions of olivine (Fo69Fa31) and diopside (En48Wo42Fs10), as well as the high Ni content of the sulfide-metal alloy, indicate a LL ordinary chondrite origin in accord with previous classifications. Although no impact crater exists at the surface of RB-QD04-0042, transmission electron microscopy revealed the presence of various shock defects in constituent minerals. These defects are planar fractures and [001] screw dislocations in olivine, multiple {101} deformation twins in tetrataenite and basal (0001) stacking faults in troilite. These diagnostic shock indicators occur only in a small zone on one concave side of the dust particle characterized by a high fracture density. These observations can be explained by a collisional event that spalled off material from the particle's surface. Alternatively, the dust particle itself could be a spallation fragment of an impact into a larger regolith target. This suggests that Itokawa dust particles lacking visible microcraters on their surfaces might have still experienced shock metamorphism and were involved in collisional fragmentation that resulted in the formation of regolith.

  9. Origin of Cancer: An Information, Energy, and Matter Disease

    PubMed Central

    Hanselmann, Rainer G.; Welter, Cornelius

    2016-01-01

    Cells are open, highly ordered systems that are far away from equilibrium. For this reason, the first function of any cell is to prevent the permanent threat of disintegration that is described by thermodynamic laws and to preserve highly ordered cell characteristics such as structures, the cell cycle, or metabolism. In this context, three basic categories play a central role: energy, information, and matter. Each of these three categories is equally important to the cell and they are reciprocally dependent. We therefore suggest that energy loss (e.g., through impaired mitochondria) or disturbance of information (e.g., through mutations or aneuploidy) or changes in the composition or distribution of matter (e.g., through micro-environmental changes or toxic agents) can irreversibly disturb molecular mechanisms, leading to increased local entropy of cellular functions and structures. In terms of physics, changes to these normally highly ordered reaction probabilities lead to a state that is irreversibly biologically imbalanced, but that is thermodynamically more stable. This primary change—independent of the initiator—now provokes and drives a complex interplay between the availability of energy, the composition, and distribution of matter and increasing information disturbance that is dependent upon reactions that try to overcome or stabilize this intracellular, irreversible disorder described by entropy. Because a return to the original ordered state is not possible for thermodynamic reasons, the cells either die or else they persist in a metastable state. In the latter case, they enter into a self-driven adaptive and evolutionary process that generates a progression of disordered cells and that results in a broad spectrum of progeny with different characteristics. Possibly, 1 day, one of these cells will show an autonomous and aggressive behavior—it will be a cancer cell. PMID:27909692

  10. Origin of Cancer: An Information, Energy, and Matter Disease.

    PubMed

    Hanselmann, Rainer G; Welter, Cornelius

    2016-01-01

    Cells are open, highly ordered systems that are far away from equilibrium. For this reason, the first function of any cell is to prevent the permanent threat of disintegration that is described by thermodynamic laws and to preserve highly ordered cell characteristics such as structures, the cell cycle, or metabolism. In this context, three basic categories play a central role: energy, information, and matter. Each of these three categories is equally important to the cell and they are reciprocally dependent. We therefore suggest that energy loss (e.g., through impaired mitochondria) or disturbance of information (e.g., through mutations or aneuploidy) or changes in the composition or distribution of matter (e.g., through micro-environmental changes or toxic agents) can irreversibly disturb molecular mechanisms, leading to increased local entropy of cellular functions and structures. In terms of physics, changes to these normally highly ordered reaction probabilities lead to a state that is irreversibly biologically imbalanced, but that is thermodynamically more stable. This primary change-independent of the initiator-now provokes and drives a complex interplay between the availability of energy, the composition, and distribution of matter and increasing information disturbance that is dependent upon reactions that try to overcome or stabilize this intracellular, irreversible disorder described by entropy. Because a return to the original ordered state is not possible for thermodynamic reasons, the cells either die or else they persist in a metastable state. In the latter case, they enter into a self-driven adaptive and evolutionary process that generates a progression of disordered cells and that results in a broad spectrum of progeny with different characteristics. Possibly, 1 day, one of these cells will show an autonomous and aggressive behavior-it will be a cancer cell.

  11. PHYS: Division of Physical Chemistry 258 - Properties and Origins of Cometary and Asteroidal Organic Matter Delivered to the Early Earth

    NASA Technical Reports Server (NTRS)

    Messenger, Scott; Nguyen, Ann

    2017-01-01

    Comets and asteroids may have contributed much of the Earth's water and organic matter. The Earth accretes approximately 4x10(exp 7) Kg of dust and meteorites from these sources every year. The least altered meteorites contain complex assemblages of organic compounds and abundant hydrated minerals. These carbonaceous chondrite meteorites probably derive from asteroids that underwent hydrothermal processing within the first few million years after their accretion. Meteorite organics show isotopic and chemical signatures of low-T ion-molecule and grain-surface chemistry and photolysis of icy grains that occurred in cold molecular clouds and the outer protoplanetary disk. These signatures have been overprinted by aqueously mediated chemistry in asteroid parent bodies, forming amino acids and other prebiotic molecules. Comets are much richer in organic matter but it is less well characterized. Comet dust collected in the stratosphere shows larger H and N isotopic anomalies than most meteorites, suggesting better preservation of primordial organics. Rosetta studies of comet 67P coma dust find complex organic matter that may be related to the macromolecular material that dominates the organic inventory of primitive meteorites. The exogenous organic material accreting on Earth throughout its history is made up of thousands of molecular species formed in diverse processes ranging from circumstellar outflows to chemistry at near absolute zero in dark cloud cores and the formative environment within minor planets. NASA and JAXA are currently flying sample return missions to primitive, potentially organic-rich asteroids. The OSIRIS-REx and Hayabusa2 missions will map their target asteroids, Bennu and Ryugu, in detail and return regolith samples to Earth. Laboratory analyses of these pristine asteroid samples will provide unprecedented views of asteroidal organic matter relatively free of terrestrial contamination within well determined geological context. Studies of

  12. An original data treatment for infrared spectra of organic matter, application to extracted soil organic matter

    NASA Astrophysics Data System (ADS)

    Gomes Rossin, Bruna; Redon, Roland; Raynaud, Michel; Nascimento, Nadia Regina; Mounier, Stéphane

    2017-04-01

    Infrared spectra of extracted organic matter are easy and rapid to do, but generally hard to interpreted over the presence or not of certain organic functions. Indeed, the organic matter is a complex mixture of molecules often having absorption overlapping and it is also difficult to have a well calibrated or normalised spectra due to the difficulty to have a well known solid content or homogeneity for a sample (Monakhova et al. 2015, Tadini et al. 2015, Bardy et al. 2008). In this work, the IRTF (InfraRed Fourier Transform) spectra were treated by an original algorithm developed to obtain the principal components of the IRTF spectra and their contributions for each sample. This bilinear decomposition used a PCA initialisation and the principal components were estimated from vectors calculated by PCA and linearly combined to provide non-negative signals minimizing a criterion based on cross-correlation. Hence, using this decomposition, it is possible to define IRTF signal of organic matter fractions like humic acid or fulvic acid depending on their origin like surface of depth of soil profiles. The method was used on a set of sample from Upper Negro River Basin (Amazon, Brazil) (Bueno,2009), where three soils sequences from surface to two meter depth containing 10 slices each. The sequences were sampled on a podzol well drain, a hydromorphic podzol and a cryptopodzol. From the IRTF data five representative component spectra were defined for all the extracted organic matter , and using other chemical composition information, a mechanism of organic matter fate is proposed to explain the observed results. Bardy, M., E. Fritsch, S. Derenne, T. Allard, N. R. do Nascimento, and G. T. Bueno. 2008. "Micromorphology and Spectroscopic Characteristics of Organic Matter in Waterlogged Podzols of the Upper Amazon Basin." Geoderma 145 (3-4): 222-30. Bueno, G.T. Appauvrissement et podzolisation des latérites du baissin du Rio Negro et gênese dês Podzols dans le haut bassin

  13. Carbonaceous Chondrite Clasts in HED Achondrites

    NASA Technical Reports Server (NTRS)

    Zolensky, M. E.; Weisberg, M. K.; Buchanan, P. C.; Mittlefehldt, David W.

    1996-01-01

    Since carbonaceous chondrite planetesimals are attractive candidates for the progenitors of HED asteroid(s), we have performed a survey of HED meteorites in order to locate and characterize the mineralogy, chemistry, and petrography of the oft-reported carbonaceous chondrite clasts by microprobe, SEM-EDX. and TEM techniques. We examined samples of all HEDs we could lay our gloved hands on, and found carbonaceous chondrite clasts in the howardites Kapoeta, Jodzie, EET 87513, Y 793497, LEW 85441, LEW 87015, and G'Day, the polymict eucrites LEW 97295 and LEW 95300, and the diogenite Ellemeet. We verified previous suggestions that the majority (about 80%) of these clasts are CM2 material, but we discovered that a significant proportion are CR2 (about 20%) and other rare types are present. We conclude that chondritic compounds of mixed CM2 and CR2 materials should be investigated in future geochemical modeling of the origin of the HED asteroid(s).

  14. Origins of the isospin violation of dark matter interactions

    SciTech Connect

    Gao, Xin; Kang, Zhaofeng; Li, Tianjun E-mail: zhaofengkang@gmail.com

    2013-01-01

    Light dark matter (DM) with a large DM-nucleon spin-independent scattering cross section and moreover proper isospin violation (ISV) f{sub n}/f{sub p} ≈ −0.7 may provide a way to understand the confusing DM direct detection results. Further using the stringent astrophysical and collider constraints, we systematically investigate the origin of ISV first via general operator analyses and further via specifying three types of mediators: a light Z' from chiral U(1){sub X}, an approximate spectator Higgs doublet (It can explain the W+jj anomaly simultaneously) and color triplets. In addition, although Z' from an exotic U(1){sub X} mixing with U(1){sub Y} generates only f{sub n} = 0, we can combine it with the conventional Higgs to achieve the proper ISV. As a concrete example, we propose the U(1){sub X} model where the U(1){sub X} charged light sneutrino is an inelastic DM, which dominantly annihilates to light dark states such as Z' with sub-GeV mass. The model can consistently (with other DM direct detection results) and safely interpret the recent GoGeNT annual modulation result.

  15. Chondrites and the Protoplanetary Disk, Part 1

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The papers discussed the following: The Formation Process of Adhering and Consorting Compound Chondrules Inferred Their Petrology and Major-Element Composition. The Prospect of High-Precision Pb Isotopic Dating of Meteorites. Evolution of UV-Irradiated Protoplanetary Disks. A Model for the Formation of E Chondrites. Oxygen Isotopic Diffusion and Exchange Experiments on Olivine and Chondrule Melts: Preliminary Results. Shock Heating: Origin of Shock Waves in the Protoplanetary Disk. Thermal Structures of Protoplanetary Disks. Meteoritical Astrophysics: A New Subdiscipline. Origin and Thermal History of FeNi-Metal in Primitive Chondrites. The Collisions of Chondrules Behind Shock Waves. Primary Signatures of the Nebular Dust Preserved in Accretionary Rims and Matrices of CV Chondrites. History of Thermally Processed Solids in the Protoplanetary Disk: Reconciling Theoretical Models and Meteoritical. Evidence Evaporation and Condensation During CAI and Chondrule Formation. Shock Heating: Effects on Chondritic Material. Rhounite-bearing Inclusions E201 and E202 from Efremovka: Constraints from Trace. Element Measurements Element Mapping in Anhydrous IDPs: Identification of the Host Phases of Major/Minor Elements as a Test of Nebula Condensation Models. Theoretical Studies of Disk Evolution Around Solar Mass Stars. Chemical Effects of High-Temperature Processing of Silicates. I-Xe and the Chronology of the Early Solar System. The Effects of X-Rays on the Gas and Dust in Young Stellar Objects. Origin of Short-lived Radionuclides in the Early Solar System. On Early Solar System Chronology: Implications of an Initially Heterogeneous Distribution of Short-lived Radionuclides. The Origin of Short-lived Radionuclides and Early Solar System Irradiation. Disequilibrium Melting and Oxygen Isotope Exchange of CAIs and Chondrules in the Solar Nebula. Mineralogy and Chemistry of Fine-grained Matrices, Rims, and Dark Inclusions in the CR Carbonaceous Chondrites Acfer/El Djouf 001 and

  16. Chondrites and the Protoplanetary Disk, Part 1

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The papers discussed the following: The Formation Process of Adhering and Consorting Compound Chondrules Inferred Their Petrology and Major-Element Composition. The Prospect of High-Precision Pb Isotopic Dating of Meteorites. Evolution of UV-Irradiated Protoplanetary Disks. A Model for the Formation of E Chondrites. Oxygen Isotopic Diffusion and Exchange Experiments on Olivine and Chondrule Melts: Preliminary Results. Shock Heating: Origin of Shock Waves in the Protoplanetary Disk. Thermal Structures of Protoplanetary Disks. Meteoritical Astrophysics: A New Subdiscipline. Origin and Thermal History of FeNi-Metal in Primitive Chondrites. The Collisions of Chondrules Behind Shock Waves. Primary Signatures of the Nebular Dust Preserved in Accretionary Rims and Matrices of CV Chondrites. History of Thermally Processed Solids in the Protoplanetary Disk: Reconciling Theoretical Models and Meteoritical. Evidence Evaporation and Condensation During CAI and Chondrule Formation. Shock Heating: Effects on Chondritic Material. Rhounite-bearing Inclusions E201 and E202 from Efremovka: Constraints from Trace. Element Measurements Element Mapping in Anhydrous IDPs: Identification of the Host Phases of Major/Minor Elements as a Test of Nebula Condensation Models. Theoretical Studies of Disk Evolution Around Solar Mass Stars. Chemical Effects of High-Temperature Processing of Silicates. I-Xe and the Chronology of the Early Solar System. The Effects of X-Rays on the Gas and Dust in Young Stellar Objects. Origin of Short-lived Radionuclides in the Early Solar System. On Early Solar System Chronology: Implications of an Initially Heterogeneous Distribution of Short-lived Radionuclides. The Origin of Short-lived Radionuclides and Early Solar System Irradiation. Disequilibrium Melting and Oxygen Isotope Exchange of CAIs and Chondrules in the Solar Nebula. Mineralogy and Chemistry of Fine-grained Matrices, Rims, and Dark Inclusions in the CR Carbonaceous Chondrites Acfer/El Djouf 001 and

  17. Exploring the origins of grey matter damage in multiple sclerosis.

    PubMed

    Calabrese, Massimiliano; Magliozzi, Roberta; Ciccarelli, Olga; Geurts, Jeroen J G; Reynolds, Richard; Martin, Roland

    2015-03-01

    Multiple sclerosis is characterized at the gross pathological level by the presence of widespread focal demyelinating lesions of the myelin-rich white matter. However, it is becoming clear that grey matter is not spared, even during the earliest phases of the disease. Furthermore, grey matter damage may have an important role both in physical and cognitive disability. Grey matter pathology involves both inflammatory and neurodegenerative mechanisms, but the relationship between the two is unclear. Histological, immunological and neuroimaging studies have provided new insight in this rapidly expanding field, and form the basis of the most recent hypotheses on the pathogenesis of grey matter damage.

  18. The Distribution of Major Carbonaceous Components in Chondritic Materials

    NASA Astrophysics Data System (ADS)

    Chan, Q. H. S.; Zolensky, M. E.; Bodnar, R. J.; Farley, C.; Cheung, J. C. H.

    2017-02-01

    With the use of Raman spectroscopy we present a study of the structure of the organic matter in the matrix and carbonate phases in five CM chondrites: Jbilet Winselwan, Murchison, Nogoya, Santa Cruz, and Wisconsin Range 91600.

  19. A non-primitive origin of near-chondritic S-Se-Te ratios in mantle peridotites; implications for the Earthʼs late accretionary history

    NASA Astrophysics Data System (ADS)

    König, Stephan; Lorand, Jean-Pierre; Luguet, Ambre; Graham Pearson, D.

    2014-01-01

    The chalcophile and highly siderophile elements Se and Te, like the other Highly Siderophile Elements (HSE) in the terrestrial mantle, may constitute powerful key tracers for meteoritic materials that hit the Earth in its latest accretionary stages (“Late Veneer”). Here the Se and Te systematics of mantle-derived peridotites (orogenic peridotites, ophiolites, cratonic peridotite xenoliths) are assessed. Combined with published in-situ analyses of HSE host minerals, whole-rock data are modelled with respect to current petrogenetic models that affect mantle composition, for example partial melting and magmatic refertilisation. We demonstrate that the near-chondritic Se/Te signature (SeN/TeN≈9±4; N = CI-chondrite normalised) of “fertile” ophiolitic and orogenic lherzolites cannot be a primitive signature of the Earth's mantle. This signature can however be explained by simple refertilisation models. The HSE-Se-Te budget of these fertile rocks can be modelled by mixing various proportions of a residual assemblage of Fe-Ni monosulphide solid solutions (Mss) and/or refractory platinum group minerals (PGMs - Ru-Os-Ir sulphides + Pt-Ir-Os alloys) with a metasomatic assemblage comprising low-temperature Pt-Pd-Te phases and Cu-Ni-rich sulphides. On the other hand, the reported Se and Te ratios in fertile peridotites are not consistent with melt depletion alone. Additions of late-stage metasomatic S-Se-Te-HSE-rich phases render Primitive Upper Mantle (PUM) estimates for Se and Te highly debatable, especially without appropriate consideration of refertilisation and metasomatism. Our results indicate that there is currently no firm evidence for chondritic S-Se-Te signatures in the Primitive Upper Mantle. This conclusion challenges the simplistic perception that near-chondritic Se/Te ratios may readily trace the Late Veneer composition.

  20. Primitive ultrafine matrix in ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Rambaldi, E. R.; Fredriksson, B. J.; Fredriksson, K.

    1981-01-01

    Ultrafine matrix material has been concentrated by sieving and filtering disaggregated samples of six ordinary chondrites of different classes. This component(s), 'Holy Smoke' (HS), is enriched in both volatile, e.g. Na, K, Zn, Sb, and Pb, as well as refractory elements, e.g. W and REE; however, the element ratios vary greatly among the different chondrites. SEM studies show that HS contains fragile crystals, differing in composition, and apparently in gross disequilibrium not only among themselves but also with the major mineral phases and consequently thermodynamic equilibration did not occur. Thus HS must have originated from impacting bodies and/or was inherent in the 'primitive' regolith. Subsequent impact brecciation and reheating appears to have altered, to varying degrees, the original composition of this ultrafine matrix material. Recent 'cosmic dust' studies may indicate that HS still exists in the solar system. Survival of such delicate material must be considered in all theories for the origin of chondrites.

  1. Exodus: Hidden origin of dark matter and baryons

    NASA Astrophysics Data System (ADS)

    Unwin, James

    2013-06-01

    We propose a new framework for explaining the proximity of the baryon and dark matter relic densities ΩDM ≈ 5Ω B . The scenario assumes that the number density of the observed dark matter states is generated due to decays from a second hidden sector which simultaneously generates the baryon asymmetry. In contrast to asymmetric dark matter models, the dark matter can be a real scalar or Majorana fermion and thus presents distinct phenomenology. We discuss aspects of model building and general constraints in this framework. Moreover, we argue that this scenario circumvents several of the experimental bounds which significantly constrain typical models of asymmetric dark matter. We present a simple supersymmetric implementation of this mechanism and show that it can be used to obtain the correct dark matter relic density for a bino LSP.

  2. Oxygen isotopic relationships between the LEW85332 carbonaceous chondrite and CR chondrites

    NASA Technical Reports Server (NTRS)

    Prinz, M.; Weisberg, M. K.; Clayton, R. N.; Mayeda, T. K.

    1993-01-01

    LEW85332, originally described as a unique C3 chondrite, was shown to be a C2 chondrite with important linkages to the CR clan. An important petrologic aspect of LEW85332 is that it contains anhydrous chondrules and hydrated matrix, and new oxygen isotopic data on chondrules, matrix and whole rock are consistent with the petrology. Chondrules fall on the equilibrated chondrite line (ECL), with a slope near 1, which goes through ordinary chondrite chondrules. This contrasts with the CR chondrule line which has a lower slope due to hydrated components. LEW85332 chondrules define a new carbonaceous chondrite chondrule line, parallel to the anhydrous CV chondrule line (CCC), consistent with the well-established concept of two oxygen isotopic reservoirs. Matrix and whole rock fall on the CR line. The whole rock composition indicates that the chondrite is dominated by chondrules, and that most of them contain light oxygen similar to that of anhydrous olivine and pyroxene separates in the Renazzo and Al Rais CR chondrites.

  3. Osmium Isotopic Compositions of Chondrites and Earth's Primitive Upper Mantle: Constraints on the Late Veneer

    NASA Technical Reports Server (NTRS)

    Walker, R. J.; Horan, M. F.; Morgan, J. W.; Meisel, T.

    2001-01-01

    The 187 Os/188 Os of carbonaceous chondrites averages approximately 2% lower than for enstatite and ordinary chondrites. The primitive upper mantle ratio for the Earth best matches that of ordinary and enstatite chondrites. Additional information is contained in the original extended abstract.

  4. Characterization of carbonaceous matter in xenolithic clasts from the Sharps (H3.4) meteorite: Constraints on the origin and thermal processing

    NASA Astrophysics Data System (ADS)

    Kebukawa, Yoko; Zolensky, Michael E.; Chan, Queenie H. S.; Nagao, Keisuke; Kilcoyne, A. L. David; Bodnar, Robert J.; Farley, Charles; Rahman, Zia; Le, Loan; Cody, George D.

    2017-01-01

    Primitive xenolithic clasts, often referred to as ;dark clasts;, are well known in many regolith breccias. The Sharps H3.4 ordinary chondrite contains unusually large dark clasts up to ∼1 cm across. Poorly-graphitized carbon (PGC), with Fe, Ni metal and described as ;carbon-rich aggregates;, has been reported in these clasts (Brearley, 1990). We report detailed analyses of carbonaceous matter in several identical Sharps clasts using FTIR, Raman, C-XANES, and TEM that provide insight on the extent of thermal processing and possible origin of such clasts. We also prepared acid residues of the clasts using the HCl/HF method and conducted mass spectrometric analysis of the entrained noble gases. Carbonaceous matter is often used to infer thermal history due to its sensitivity to thermal processes. The FTIR spectra of the acid residue from the Sharps clast suggest that carbonaceous matter in the clast contains less hydrogen and oxygen compared to acid residues from typical type 3.4 ordinary chondrites. The metamorphic temperatures obtained by Raman spectroscopy ranges between ∼380 °C and ∼490 °C. TEM observations indicate that the clasts experienced a peak temperature of 300 °C to 400 °C, based on the carbon d002 layer lattice spacing of C-rich aggregates. These estimates are consistent with an earlier estimate of 330 ± 50 °C, that is also estimated by the d002 layer lattice spacing (Brearley, 1990). It should be noted that the lattice spacing thermometer is based on terrestrial metamorphose rocks, and thus temperature was probably underestimated. Meanwhile, the C-XANES spectra of the C-rich aggregates show high exciton intensities, indicative of graphene structures that developed at around 700-800 °C following an extensive period of time (millions of years), however, the surrounding matrix areas experienced lower temperatures of less than 300-500 °C. Noble gas analysis of the acid residue from the Sharps clasts shows that the residue is almost identical

  5. Characterization of carbonaceous matter in xenolithic clasts from the Sharps (H3.4) meteorite: Constraints on the origin and thermal processing

    SciTech Connect

    Kebukawa, Yoko; Zolensky, Michael E.; Chan, Queenie H. S.; Nagao, Keisuke; Kilcoyne, A. L. David; Bodnar, Robert J.; Farley, Charles; Rahman, Zia; Le, Loan; Cody, George D.

    2016-09-25

    Primitive xenolithic clasts, often referred to as “dark clasts”, are well known in many regolith breccias. The Sharps H3.4 ordinary chondrite contains unusually large dark clasts up to ~1 cm across. Poorly-graphitized carbon (PGC), with Fe, Ni metal and described as “carbon-rich aggregates”, has been found in these clasts (Brearley, 1990). We report detailed analyses of carbonaceous matter in several identical Sharps clasts using FTIR, Raman, C-XANES, and TEM that provide insight on the extent of thermal processing and possible origin of such clasts. We also prepared acid residues of the clasts using the HCl/HF method and conducted mass spectrometric analysis of the entrained noble gases. Carbonaceous matter is often used to infer thermal history due to its sensitivity to thermal processes. The FTIR spectra of the acid residue from the Sharps clast suggest that carbonaceous matter in the clast contains less hydrogen and oxygen compared to acid residues from typical type 3.4 ordinary chondrites. The metamorphic temperatures obtained by Raman spectroscopy ranges between ~380 °C and ~490 °C. TEM observations indicate that the clasts experienced a peak temperature of 300 °C to 400 °C, based on the carbon d 002 layer lattice spacing of C-rich aggregates. These estimates are consistent with an earlier estimate of 330 ± 50 °C, that is also estimated by the d 002 layer lattice spacing (Brearley, 1990). It should be noted that the lattice spacing thermometer is based on terrestrial metamorphose rocks, and thus temperature was probably underestimated. Meanwhile, the C-XANES spectra of the C-rich aggregates show high exciton intensities, indicative of graphene structures that developed at around 700–800 °C following an extensive period of time (millions of years), however, the surrounding matrix areas experienced lower temperatures of less than 300–500 °C. Noble gas analysis of the acid residue from the Sharps clasts shows that the residue is

  6. Thermodynamic Equilibrium in the Origin of Organic Matter

    NASA Technical Reports Server (NTRS)

    Dayhoff, M. O.; Eck, R. V.; Lippincott, E. R.; Pratt, Y. T.

    1966-01-01

    Theoretical and experimental support is presented for the hypothesis that organic compounds occurring in carbonaceous chondrites may have formed under equilibrium or near equilibrium conditions. The equilibrium distributions of organic compounds at temperature between 300 and 1000 K and pressures of 10(exp 16) to 50 atmospheres for the C-H-O system have been computed. At high temperatures and low pressures aromatic compounds may form even in the presence of excess hydrogen. Equilibrium concentrations of numerous compounds possible at 1000 K when N, S, and C1 are added to the system have also been determined. A limited equilibrium method is employed in which those few compounds which form with most difficulty are excluded from the computations. This approach is shown to be useful in the interpretation of certain experimental data. In preliminary experiments it has been found that gases, converted to the plasma state by high energy radio frequency discharge, yield product mixtures which are in qualitative agreement with those predicted.

  7. Post-Inflationary Higgs Relaxation and the Origin of Matter

    NASA Astrophysics Data System (ADS)

    Yang, Louis

    2015, the ATLAS and CMS Collaborations have reported evidence of a diphoton excess which may be interpreted as a pseudoscalar boson S with a mass around 750 GeV. To explain the diphoton excess, such a boson is coupled to the Standard Model gauge fields via SFF˜ -dual operators, which provide the chemical potential to the lepton asymmetry. Although the diphoton excess turns out to be a statistical fluctuation in 2016, a similar pseudoscalar with greater mass remains a viable model for relaxation leptogenesis mechanism. Finally, we discuss the imprint of relaxation leptogenesis on the CIB anisotropy. Observations of CIB exhibit significant fluctuations on small angular scales, whose origin remains a question. We consider the possibility that small-scale fluctuations in matter-antimatter asymmetry could lead to variations in star formation rates which are responsible for the CIB fluctuations. We show that the Higgs relaxation leptogenesis mechanism can produce such small-scale baryonic isocurvature perturbations which can explain the observed excess in the CIB fluctuations.

  8. The secondary history of Sutter's Mill CM carbonaceous chondrite based on water abundance and the structure of its organic matter from two clasts

    NASA Astrophysics Data System (ADS)

    Beck, P.; Quirico, E.; Garenne, A.; Yin, Q.-Z.; Bonal, L.; Schmitt, B.; Montes-Hernandez, G.; Montagnac, G.; Chiriac, R.; Toche, F.

    2014-11-01

    Sutter's Mill is a regolith breccia composed of both heavily altered clasts and more reduced xenoliths. Here, we present a detailed investigation of fragments of SM18 and SM51. We have characterized the water content and the mineralogy by infrared (IR) and thermogravimetric analysis (TGA) and the structure of the organic compounds by Raman spectroscopy, to characterize the secondary history of the clasts, including aqueous alteration and thermal metamorphism. The three methods used in this study suggest that SM18 was significantly heated. The amount of water contained in phyllosilicates derived by TGA is estimated to be approximately 3.2 wt%. This value is quite low compared with other CM chondrites that typically range from 6 to 12 wt%. The infrared transmission spectra of SM18 show that the mineralogy of the sample is dominated by a mixture of phyllosilicate and olivine. SM18 shows an intense peak at 11.2 μm indicative of olivine (Fig. 1). If we compare SM18 with other CM and metamorphosed CM chondrites, it shows one of the most intense olivine signatures, and therefore a lower proportion of phyllosilicate minerals. The Raman results tend to support a short-duration heating hypothesis. In the ID/IG versus FWHM-D diagram, SM18 appears to be unusual compared to most CM samples, and close to the metamorphosed CM chondrites Pecora Escarpment (PCA) 91008 and PCA 02012. In the case of SM51, infrared spectroscopy reveals that olivine is less abundant than in SM18 and the 10 μm silicate feature is more similar to that of moderately altered CM chondrites (like Murchison or Queen Alexandra Range [QUE] 97990). Raman spectroscopy does not clearly point to a heating event for SM51 in the ID/IG versus FWHM-D diagram. However, TGA analysis suggests that SM51 was slightly dehydrated as the amount of water contained in phyllosilicates is approximately 3.7 wt%, which is higher than SM18, but still lower than phyllosilicate water contents in weakly altered CM chondrites

  9. Sterile neutrinos as the origin of dark and baryonic matter.

    PubMed

    Canetti, Laurent; Drewes, Marco; Shaposhnikov, Mikhail

    2013-02-08

    We demonstrate for the first time that three sterile neutrinos alone can simultaneously explain neutrino oscillations, the observed dark matter, and the baryon asymmetry of the Universe without new physics above the Fermi scale. The key new point of our analysis is leptogenesis after sphaleron freeze-out, which leads to resonant dark matter production, evading thus the constraints on sterile neutrino dark matter from structure formation and x-ray searches. We identify the range of sterile neutrino properties that is consistent with all known constraints. We find a domain of parameters where the new particles can be found with present day experimental techniques, using upgrades to existing experimental facilities.

  10. Matrix and fine-grained rims in the unequilibrated CO3 chondrite, ALHA77307 - Origins and evidence for diverse, primitive nebular dust components

    NASA Technical Reports Server (NTRS)

    Brearley, Adrian J.

    1993-01-01

    SEM, TEM, and electron microprobe analysis were used to investigate in detail the mineralogical and chemical characteristics of dark matrix and fine-grained rims in the unequilibrated CO3 chondrite ALHA77307. Data obtained revealed that there was a remarkable diversity of distinct mineralogical components, which can be identified using their chemical and textural characteristics. The matrix and rim components in ALHA77307 formed by disequilibrium condensation process as fine-grained amorphous dust that is represented by the abundant amorphous component in the matrix. Subsequent thermal processing of this condensate material, in a variety of environments in the nebula, caused partial or complete recrystallization of the fine-grained dust.

  11. Matrix and fine-grained rims in the unequilibrated CO3 chondrite, ALHA77307 - Origins and evidence for diverse, primitive nebular dust components

    NASA Astrophysics Data System (ADS)

    Brearley, A. J.

    1993-04-01

    SEM, TEM, and electron microprobe analysis were used to investigate in detail the mineralogical and chemical characteristics of dark matrix and fine-grained rims in the unequilibrated CO3 chondrite ALHA77307. Data obtained revealed that there was a remarkable diversity of distinct mineralogical components, which can be identified using their chemical and textural characteristics. The matrix and rim components in ALHA77307 formed by disequilibrium condensation process as fine-grained amorphous dust that is represented by the abundant amorphous component in the matrix. Subsequent thermal processing of this condensate material, in a variety of environments in the nebula, caused partial or complete recrystallization of the fine-grained dust.

  12. Chondrites and the Protoplanetary Disk, Part 2

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Contents include the following: On the Dynamical Evolution of a Nebula and Its Effect on Dust Coagulation and the Formation of Centimeter-sized Particles. The Mineralogy and Grain Properties of the Disk Surfaces in Three Herbig Ae/Be Stars. Astrophysical Observations of Disk Evolution Around Solar Mass Stars. The Systematic Petrology of Chondrites: A Consistent Approach to Assist Classification and Interpretation. Understanding Our Origins: Formation of Sun-like Stars in H II Region Environments. Chondrule Crystallization Experiments. Formation of SiO2-rich Chondrules by Fractional Condensation. Refractory Forsterites from Murchison (CM2) and Yamato 81020 (CO3.0) Chondrites: Cathodoluminescence, Chemical Compositions and Oxygen Isotopes. Apparent I-Xe Cooling Rates of Chondrules Compared with Silicates from the Colomera Iron Meteorite. Chondrule Formation in Planetesimal Bow Shocks: Physical Processes in the Near Vicinity of the Planetesimal. Genetic Relationships Between Chondrules, Rims and Matrix. Chondrite Fractionation was Cosmochemical; Chondrule Fractionation was Geochemical. Chondrule Formation and Accretion of Chondrite Parent Bodies: Environmental Constraints. Amoeboid Olivine Aggregates from the Semarkona LL3.0 Chondrite. The Evolution of Solids in Proto-Planetary Disks. New Nickel Vapor Pressure Measurements: Possible Implications for Nebular Condensates. Chemical, Mineralogical and Isotopic Properties of Chondrules: Clues to Their Origin. Maximal Size of Chondrules in Shock-Wave Heating Model: Stripping of Liquid Surface in Hypersonic Rarefied Gas Flow. The Nature and Origin of Interplanetary Dust: High Temperature Components. Refractory Relic Components in Chondrules from Ordinary Chondrites. Constraints on the Origin of Chondrules and CAIs from Short-lived and Long-lived Radionuclides. The Genetic Relationship Between Refractory Inclusions and Chondrules. Contemporaneous Chondrule Formation Between Ordinary and Carbonaceous Chondrites. Chondrules and

  13. Chondrites and the Protoplanetary Disk, Part 2

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Contents include the following: On the Dynamical Evolution of a Nebula and Its Effect on Dust Coagulation and the Formation of Centimeter-sized Particles. The Mineralogy and Grain Properties of the Disk Surfaces in Three Herbig Ae/Be Stars. Astrophysical Observations of Disk Evolution Around Solar Mass Stars. The Systematic Petrology of Chondrites: A Consistent Approach to Assist Classification and Interpretation. Understanding Our Origins: Formation of Sun-like Stars in H II Region Environments. Chondrule Crystallization Experiments. Formation of SiO2-rich Chondrules by Fractional Condensation. Refractory Forsterites from Murchison (CM2) and Yamato 81020 (CO3.0) Chondrites: Cathodoluminescence, Chemical Compositions and Oxygen Isotopes. Apparent I-Xe Cooling Rates of Chondrules Compared with Silicates from the Colomera Iron Meteorite. Chondrule Formation in Planetesimal Bow Shocks: Physical Processes in the Near Vicinity of the Planetesimal. Genetic Relationships Between Chondrules, Rims and Matrix. Chondrite Fractionation was Cosmochemical; Chondrule Fractionation was Geochemical. Chondrule Formation and Accretion of Chondrite Parent Bodies: Environmental Constraints. Amoeboid Olivine Aggregates from the Semarkona LL3.0 Chondrite. The Evolution of Solids in Proto-Planetary Disks. New Nickel Vapor Pressure Measurements: Possible Implications for Nebular Condensates. Chemical, Mineralogical and Isotopic Properties of Chondrules: Clues to Their Origin. Maximal Size of Chondrules in Shock-Wave Heating Model: Stripping of Liquid Surface in Hypersonic Rarefied Gas Flow. The Nature and Origin of Interplanetary Dust: High Temperature Components. Refractory Relic Components in Chondrules from Ordinary Chondrites. Constraints on the Origin of Chondrules and CAIs from Short-lived and Long-lived Radionuclides. The Genetic Relationship Between Refractory Inclusions and Chondrules. Contemporaneous Chondrule Formation Between Ordinary and Carbonaceous Chondrites. Chondrules and

  14. One-pot synthesis of amino acid precursors with insoluble organic matter in planetesimals with aqueous activity

    PubMed Central

    Kebukawa, Yoko; Chan, Queenie H. S.; Tachibana, Shogo; Kobayashi, Kensei; Zolensky, Michael E.

    2017-01-01

    The exogenous delivery of organic molecules could have played an important role in the emergence of life on the early Earth. Carbonaceous chondrites are known to contain indigenous amino acids as well as various organic compounds and complex macromolecular materials, such as the so-called insoluble organic matter (IOM), but the origins of the organic matter are still subject to debate. We report that the water-soluble amino acid precursors are synthesized from formaldehyde, glycolaldehyde, and ammonia with the presence of liquid water, simultaneously with macromolecular organic solids similar to the chondritic IOM. Amino acid products from hydrothermal experiments after acid hydrolysis include α-, β-, and γ-amino acids up to five carbons, for which relative abundances are similar to those extracted from carbonaceous chondrites. One-pot aqueous processing from simple ubiquitous molecules can thus produce a wide variety of meteoritic organic matter from amino acid precursors to macromolecular IOM in chondrite parent bodies. PMID:28345041

  15. One-pot synthesis of amino acid precursors with insoluble organic matter in planetesimals with aqueous activity.

    PubMed

    Kebukawa, Yoko; Chan, Queenie H S; Tachibana, Shogo; Kobayashi, Kensei; Zolensky, Michael E

    2017-03-01

    The exogenous delivery of organic molecules could have played an important role in the emergence of life on the early Earth. Carbonaceous chondrites are known to contain indigenous amino acids as well as various organic compounds and complex macromolecular materials, such as the so-called insoluble organic matter (IOM), but the origins of the organic matter are still subject to debate. We report that the water-soluble amino acid precursors are synthesized from formaldehyde, glycolaldehyde, and ammonia with the presence of liquid water, simultaneously with macromolecular organic solids similar to the chondritic IOM. Amino acid products from hydrothermal experiments after acid hydrolysis include α-, β-, and γ-amino acids up to five carbons, for which relative abundances are similar to those extracted from carbonaceous chondrites. One-pot aqueous processing from simple ubiquitous molecules can thus produce a wide variety of meteoritic organic matter from amino acid precursors to macromolecular IOM in chondrite parent bodies.

  16. Origins of R2∗ and white matter

    PubMed Central

    Rudko, David A.; Klassen, L. Martyn; de Chickera, Sonali N.; Gati, Joseph S.; Dekaban, Gregory A.; Menon, Ravi S.

    2014-01-01

    Estimates of the apparent transverse relaxation rate () can be used to quantify important properties of biological tissue. Surprisingly, the mechanism of dependence on tissue orientation is not well understood. The primary goal of this paper was to characterize orientation dependence of in gray and white matter and relate it to independent measurements of two other susceptibility based parameters: the local Larmor frequency shift (fL) and quantitative volume magnetic susceptibility (Δχ). Through this comparative analysis we calculated scaling relations quantifying (reversible contribution to the transverse relaxation rate from local field inhomogeneities) in a voxel given measurements of the local Larmor frequency shift. is a measure of both perturber geometry and density and is related to tissue microstructure. Additionally, two methods (the Generalized Lorentzian model and iterative dipole inversion) for calculating Δχ were compared in gray and white matter. The value of Δχ derived from fitting the Generalized Lorentzian model was then connected to the observed orientation dependence using image-registered optical density measurements from histochemical staining. Our results demonstrate that the and fL of white and cortical gray matter are well described by a sinusoidal dependence on the orientation of the tissue and a linear dependence on the volume fraction of myelin in the tissue. In deep brain gray matter structures, where there is no obvious symmetry axis, and fL have no orientation dependence but retain a linear dependence on tissue iron concentration and hence Δχ. PMID:24374633

  17. Common origin of neutrino mass, dark matter and Dirac leptogenesis

    NASA Astrophysics Data System (ADS)

    Borah, Debasish; Dasgupta, Arnab

    2016-12-01

    We study the possibility of generating tiny Dirac neutrino masses at one loop level through the scotogenic mechanism such that one of the particles going inside the loop can be a stable cold dark matter (DM) candidate. Majorana mass terms of singlet fermions as well as tree level Dirac neutrino masses are prevented by incorporating the presence of additional discrete symmetries in a minimal fashion, which also guarantee the stability of the dark matter candidate. Due to the absence of total lepton number violation, the observed baryon asymmetry of the Universe is generated through the mechanism of Dirac leptogenesis where an equal and opposite amount of leptonic asymmetry is generated in the left and right handed sectors which are prevented from equilibration due to tiny Dirac Yukawa couplings. Dark matter relic abundance is generated through its usual freeze-out at a temperature much below the scale of leptogenesis. We constrain the relevant parameter space from neutrino mass, baryon asymmetry, Planck bound on dark matter relic abundance, and latest LUX bound on spin independent DM-nucleon scattering cross section. We also discuss the charged lepton flavour violation (μ → e γ) and electric dipole moment of electron in this model in the light of the latest experimental data and constrain the parameter space of the model.

  18. Ruthenium Isotopic Composition of Terrestrial Materials, Iron Meteorites and Chondrites

    NASA Technical Reports Server (NTRS)

    Becker, H.; Walker, R. J.

    2002-01-01

    Ru isotopic compositions of magmatic iron meteorites and chondrites overlap with terrestrial Ru at the 0.3 to 0.9 (epsilon) level. Additional information is contained in the original extended abstract.

  19. Primitive material surviving in chondrites - Matrix

    NASA Technical Reports Server (NTRS)

    Scott, E. R. D.; Barber, D. J.; Alexander, C. M.; Hutchinson, R.; Peck, J. A.

    1988-01-01

    A logical place to search for surviving pristine nebular material is in the fine-grained matrices of ordinary and carbonaceous chondrites of petrographic type 3. Unfortunately, many of these chondrites have experienced brecciation, thermal metamorphism, and aqueous alteration, so that interpreting individual features in terms of specific nebular conditions and/or processes is difficult. It follows that the origin and evolutionary history of such matrix phases are controversial, and a consensus is difficult to define. In this chapter, therefore, after summarizing the salient mineralogical, petrographic, chemical, and isotopic features of matrix in apparently primitive chondrites, an attempt is made to provide an overview both of areas of agreement and of topics that are currently in dispute.

  20. Isotopic constraints on the origin of meteoritic organic matter

    NASA Technical Reports Server (NTRS)

    Kerridge, J. F.

    1991-01-01

    Salient features of the isotopic distribution of H, C and N in the organic material found in carbonaceous meteorites are noted. Most organic fractions are strongly enriched in D with respect to the D/H ratio characteristic of H2 in the protosolar system; substantial variations in C-13/C-12 ratio are found among different molecular species, with oxidised species tending to be C-13 enriched relative to reduced species; some homologous series reveal systematic decrease in C-13/C-12 with increasing C number; considerable variation in N-15/N-14 ratio is observed within organic matter, though no systematic pattern to its distribution has yet emerged; no interelement correlations have been observed between isotope enrichments for the different biogenic elements. The isotopic complexity echoes the molecular diversity observed in meteoritic organic matter and suggests that the organic matter was formed by multiple processes and/or from multiple sources. However, existence of a few systematic patterns points towards survival of isotopic signatures characteristic of one or more specific processes. The widespread D enrichment implies either survival of many species of interstellar molecule or synthesis from a reservoir containing a significant interstellar component. Several of the questions raised above can be addressed by more detailed determination of the distribution of the H, C and N isotopes among different well-characterized molecular fractions. Thus, the present study is aimed at discovering whether the different amino acids have comparable D enrichments, which would imply local synthesis from a D-enriched reservoir, or very viable D enrichments, which would imply survival of some interstellar amino acids. The same approach is also being applied to polycyclic aromatic hydrocarbons. Because the analytical technique employed (secondary ion mass spectrometry) can acquire data for all three isotopic systems from each molecular fraction, any presently obscured interelement

  1. Organic matter in meteorites and comets - Possible origins

    NASA Astrophysics Data System (ADS)

    Anders, E.

    1991-04-01

    At least six extraterrestrial environments may have contributed organic compounds to meteorites and comets: solar nebula, giant-planet subnebulae, asteroid interiors containing liquid water, carbon star atmospheres, and diffuse or dark interstellar clouds. The record in meteorites is partly obscured by pervasive reheating that transformed much of the organic matter to kerogen; nonetheless, it seems that all six formation sites contributed. For comets, the large abundance of HCHO, HCN, and unsaturated hydrocarbons suggests an interstellar component of 50 percent or more, but the contributions of various interstellar processes, and of a solar-nebula component, are hard to quantify. A research program is outlined that may help reduce these uncertainties.

  2. Non-Abelian monopoles as the origin of dark matter

    NASA Astrophysics Data System (ADS)

    Falomir, H.; Gamboa, J.; Méndez, F.

    2016-07-01

    We suggest that dark matter may be partially constituted by a dilute ’t Hooft-Polyakov monopoles gas. We reach this conclusion by using the Georgi-Glashow model coupled to a dual kinetic mixing term F𝒢˜ where F is the electromagnetic field and 𝒢 the ’t Hooft tensor. We show that these monopoles carry both (Maxwell) electric and (Georgi-Glashow) magnetic charges and the electric charge quantization condition is modified in terms of a dimensionless real parameter. This parameter could be determined from milli-charged particle experiments.

  3. Organic matter in meteorites and comets - Possible origins

    NASA Technical Reports Server (NTRS)

    Anders, Edward

    1991-01-01

    At least six extraterrestrial environments may have contributed organic compounds to meteorites and comets: solar nebula, giant-planet subnebulae, asteroid interiors containing liquid water, carbon star atmospheres, and diffuse or dark interstellar clouds. The record in meteorites is partly obscured by pervasive reheating that transformed much of the organic matter to kerogen; nonetheless, it seems that all six formation sites contributed. For comets, the large abundance of HCHO, HCN, and unsaturated hydrocarbons suggests an interstellar component of 50 percent or more, but the contributions of various interstellar processes, and of a solar-nebula component, are hard to quantify. A research program is outlined that may help reduce these uncertainties.

  4. Chemical Fractionation in Chondrites by Aerodynamic Sorting of Chondritic Materials

    NASA Astrophysics Data System (ADS)

    Scott, E. R. D.; Haack, H.

    1993-07-01

    rims on spherules preclude the possibility that the spherules were released from chondrules during parent body impacts. Refractory Inclusions: The similarity in the order of chondrule and CAI sizes suggests a common size sorting process. Chondrules decrease in mean size in the order CV (1.0 mm) > CM (0.3 mm) > CO (0.15 mm) > ALH85085 (0.02 mm) [8]. Refractory inclusions decrease in size in the order CV (commonly >1 cm) > CO > CM (<1 mm) > ALH85085 (0.03 mm) [8,9]. Although many chondrules and CAIs in ALH85085 are broken, mean sizes were not much bigger originally as the grain sizes of fragments are comparable to those of complete objects [6]. Size sorting must postdate CAI formation as these size relationships hold for all kinds of CAI that formed in very different ways. Density differences cannot account for the apparently larger mean size of CAIs relative to chondrules in CV3 chondrites. Model: We suggest that a common aerodynamic sorting process may have affected all ingredients during their fall toward the proto-Sun through nebula gas. This sorting probably occurred after chondrule formation and rim acquisition in a turbulent environment [7] and ended when planetesimal accretion halted inward motion. Intermittent turbulence may have cleared the midplane of chondritic materials to allow episodic accretion of distinctly different batches of material. This model and runaway accretion of planetesimals accounts for the correlation of chondrule size with metamorphic type in CO3 chondrites [8] and provides a mechanism for understanding chemical and isotopic variations within asteroids such as the ureilite parent body. References: [1] Rubin A. E. and Keil K. (1984) Meteoritics, 19, 135-143. [2] Skinner W. R. and Leenhouts J. M. (1993) LPSC XXIV, 1315-1316. [3] Clayton R. N. et al. (1991) GCA, 55, 2317-2337. [4] Scott E. R. D. and Newsom H. E. (1989) Z. Naturforsch., 44a, 924-934. [5] Haack H. and Scott E. R. D. (1993), this volume. [6] Scott E. R. D. et al. (1984) GCA, 48

  5. Separation of spallation and terrestrial C-14 in chondrites

    NASA Technical Reports Server (NTRS)

    Cresswell, R. G.; Beukens, R. P.; Rucklidge, J. C.

    1993-01-01

    Weathering products and contamination severely hamper our ability to accurately measure the C-14 spallation component in meteorites, but can give insights into a sample's terrestrial history. A procedure was developed to measure the C-14 in these components using CO and CO2 separations from temperature extractions from 200-500 mg of material. The Bruderheim (L6) chondrite was chosen as a standard following the practice of previous researchers, crosschecked against Peace River (L6), Abee (EH4), and Juvinas (EUC). Low temperature fractions (less than 900 C) give C-14 signatures consistent with a modern terrestrial C-14 source; melt fractions show elevated levels attesting to a spallogenic origin. Higher yields of CO in the melt fraction are less affected by the low levels of experimental contamination than the CO2. This fraction gave a mean CO:CO2 ratio in Bruderheim of 81.6 +/- 7.7; the ratio of the spallation component is 79.8 +/- 8.1. These values suggest equilibrium release of gases on the olivine-silica-pyroxene-iron buffer. This is corroborated by approximately equal release of the two components at 900 C. The chondrites gave an average saturation level of 54.3 +/- 2.9 dpm/kg; the achondrite gave 49.6 +/- 2.0 dpm/kg. No clear correlation with oxygen content is apparent, though shielding effects have yet to be evaluated. A further evaluation of this subject matter is given.

  6. Boron in chondritic meteorites

    NASA Astrophysics Data System (ADS)

    Shaw, D. M.; Higgins, M. D.; Hinton, R. W.; Truscott, M. G.; Middleton, T. A.

    1988-09-01

    The B and Li content and distribution in 14 chondrites are investigated experimentally by means of prompt gamma neutron activation on bulk samples, EMPA, and alpha-track imaging of thin polished sections attached to neutron-irradiated cellulose nitrate films. Alpha-track and transmitted-light images are shown, and numerical results are presented in extensive tables. Chondrites of lower equilibration grades are found to contain practically no Li or B in chondrules, inclusions, sulfides, or metal, so that bulk B/Li content represents material from the matrix. Weathering products in Antarctic meteorites are shown to be significantly enriched in B and Cl, and the bulk B content in carbonaceous and ordinary chondrites is found to range from 0.2 to 1 ppm (mean 0.55 ppm).

  7. Archaeal "dark matter" and the origin of eukaryotes.

    PubMed

    Williams, Tom A; Embley, T Martin

    2014-03-01

    Current hypotheses about the history of cellular life are mainly based on analyses of cultivated organisms, but these represent only a small fraction of extant biodiversity. The sequencing of new environmental lineages therefore provides an opportunity to test, revise, or reject existing ideas about the tree of life and the origin of eukaryotes. According to the textbook three domains hypothesis, the eukaryotes emerge as the sister group to a monophyletic Archaea. However, recent analyses incorporating better phylogenetic models and an improved sampling of the archaeal domain have generally supported the competing eocyte hypothesis, in which core genes of eukaryotic cells originated from within the Archaea, with important implications for eukaryogenesis. Given this trend, it was surprising that a recent analysis incorporating new genomes from uncultivated Archaea recovered a strongly supported three domains tree. Here, we show that this result was due in part to the use of a poorly fitting phylogenetic model and also to the inclusion by an automated pipeline of genes of putative bacterial origin rather than nucleocytosolic versions for some of the eukaryotes analyzed. When these issues were resolved, analyses including the new archaeal lineages placed core eukaryotic genes within the Archaea. These results are consistent with a number of recent studies in which improved archaeal sampling and better phylogenetic models agree in supporting the eocyte tree over the three domains hypothesis.

  8. Xenon in carbonaceous chondrites.

    NASA Technical Reports Server (NTRS)

    Manuel, O. K.; Hennecke, E. W.; Sabu, D. D.

    1972-01-01

    A table showing the relative amounts of xenon isotopes in carbonaceous chondrites is presented. It is found that the enrichment of heavy xenon isotopes released from carbonaceous chondrites in the approximate temperature range from 600 to 1000 C is accompanied by an enrichment of the light xenon isotopes. The high degree of correlation between these two isotopic anomalies suggests that both result from a common source. There is no known nuclear or physical process which could produce both anomalies in situ. It is, therefore, suggested that the anomalies are the result of the release of isotopically anomalous xenon which was trapped in the meteorites.

  9. Thermal evolution of a partially differentiated H chondrite parent body

    NASA Astrophysics Data System (ADS)

    Abrahams, J. N. H.; Bryson, J. F. J.; Weiss, B. P.; Nimmo, F.

    2016-12-01

    It has traditionally been assumed that planetesimals either melted entirely or remained completely undifferentiated as they accreted. The unmelted textures and cooling histories of chondrites have been used to argue that these meteorites originated from bodies that never differentiated. However, paleomagnetic measurements indicate that some chondrites (e.g., the H chondrite Portales Valley and several CV chondrites) were magnetized by a core dynamo magnetic field, implying that their parent bodies were partially differentiated. It has been unclear, however, whether planetesimal histories consistent with dynamo production can also be consistent with the diversity of chondrite cooling rates and ages. To address this, we modeled the thermal evolution of the H chondrite parent body, considering a variety of accretion histories and parent body radii. We considered partial differentiation using two-stage accretion involving the initial formation and differentiation of a small body, followed by the later addition of low thermal conductivity chondritic material that remains mostly unmelted. We were able to reproduce the measured thermal evolution of multiple H chondrites for a range of parent body parameters, including initial radii from 70-150 km, chondritic layer thicknesses from 50 km to over 100 km, and second stage accretion times of 2.5-3 Myr after solar system formation. Our predicted rates of core cooling and crystallization are consistent with dynamo generation by compositional convection beginning 60-200 Myr after solar system formation and lasting for at least tens of millions of years. This is consistent with magnetic studies of Portales Valley [Bryson et al., this meeting]. In summary, we find that thermal models of partial differentiation are consistent the radiometric ages, magnetization, and cooling rates of a diversity H chondrites.

  10. I-Xe Studies of Chondritic Metal

    NASA Astrophysics Data System (ADS)

    Swindle, T. D.; Burkland, M. K.

    1992-07-01

    Marti et al. (1989) discovered that the metal in ordinary chondrites contains a distinct Xe isotopic signature, as well as a fission component of somewhat mysterious origin (Marti et al., 1989; Kim and Marti, 1992). In addition, the metal of some ordinary chondrites, particularly those of low metamorphic grade, contains radiogenic ^129Xe (Kim et al., 1991), presumably from the decay of ^129I (T(sub)1/2 = 15.7 Ma). We have performed I-Xe analyses on metal separates from two ordinary chondrites in an attempt to constrain the chronological history of this material. Samples of metal from H3 Dhajala (provided by K. Marti) and H4 Ste. Marguerite (provided by C. Perron) were irradiated by neutrons and then analyzed by stepwise heating in a VG5400 noble gas mass spectrometer. The neutron fluence was monitored by including a sample of Bjurbole (Hohenberg and Kennedy, 1981). Dhajala metal released about 5 x 10^-12 cm^3STP/gm of radiogenic ^129Xe, virtually all of it in the 1300 degrees C and 1400 degrees C extractions, which gave model ages of about 21 Ma and 7 Ma after Bjurbole, respectively. Ste. Marguerite metal released 6 x 10^-1 degrees cm^3STP/gm of iodine-derived ^128Xe, mostly in the lowest-temperature extractions. At higher temperatures, the radiogenic ^129Xe (1 x 1O^-12 cm^3STP/gm) is accompanied by enough ^128Xe to give an age 100 Ma after Bjurbole. Although such an age might be possible, we suspect the data reflect continued release of uncorrelated ^128Xe. The initial iodine isotopic composition in the Dhajala metal is probably bracketed by the model ratios of the 1300 degrees C and 1400 degrees C extractions. Since both are well within the range observed in other type 3 ordinary chondrites, the suggestion that fission products of ^248Cm (T(sub)1/2 = 0.4 Ma) are present (Marti et al., 1989) does not seem likely, in agreement with Kim et al. (1992). Furthermore, the metal grains from a Dhajala, a type 3 chondrite, give later apparent ages than those of most

  11. Chondrites and the Protoplanetary Disk, Part 3

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Contents include the following: Ca-, Al-Rich Inclusions and Ameoboid Olivine Aggregates: What We Know and Don t Know About Their Origin. Aluminium-26 and Oxygen Isotopic Distributions of Ca-Al-rich Inclusions from Acfer 214 CH Chondrite. The Trapping Efficiency of Helium in Fullerene and Its Implicatiion to the Planetary Science. Constraints on the Origin of Chondritic Components from Oxygen Isotopic Compositions. Role of Planetary Impacts in Thermal Processing of Chondrite Materials. Formation of the Melilite Mantle of the Type B1 CAIs: Flash Heating or Transport? The Iodine-Xenon System in Outer and Inner Portions of Chondrules from the Unnamed Antarctic LL3 Chondrite. Nucleosynthesis of Short-lived Radioactivities in Massive Stars. The Two-Fluid Analysis of the Kelvin-Helmholtz Instability in the Dust Layer of a Protoplanetary Disk: A Possible Path to the Planetesimal Formation Through the Gravitational Instability. Shock-Wave Heating Model for Chonodrule Formation: Heating Rate and Cooling Rate Constraints. Glycine Amide Hydrolysis with Water and OH Radical: A Comparative DFT Study. Micron-sized Sample Preparation for AFM and SEM. AFM, FE-SEM and Optical Imaging of a Shocked L/LL Chondrite: Implications for Martensite Formation and Wave Propagation. Infrared Spectroscopy of Chondrites and Their Components: A Link Between Meteoritics and Astronomy? Mid-Infrared Spectroscopy of CAI and Their Mineral Components. The Origin of Iron Isotope Fractionation in Chondrules, CAIs and Matrix from Allende (CV3) and Chainpur (LL3) Chondrites. Protoplanetary Disk Evolution: Early Results from Spitzer. Kinetics of Evaporation-Condensation in a Melt-Solid System and Its Role on the Chemical Composition and Evolution of Chondrules. Oxygen Isotope Exchange Recorded Within Anorthite Single Crystal in Vigarano CAI: Evidence for Remelting by High Temperature Process in the Solar Nebula. Chondrule Forming Shock Waves in Solar Nebula by X-Ray Flares. Organic Globules with Anormalous

  12. The behavior of carbonaceous matter in Tagish Lake Meteorite at high P-T: implications for the survivability of organics during petrological processes and origin of life

    NASA Astrophysics Data System (ADS)

    Stagno, V.; DU, W.

    2015-12-01

    Recent models of planets formation have faced the possibility that (volatile-rich) carbonaceous chondrites are the possible carrier of water and complex carbon molecules. The Tagish Lake (TL) meteorite is a classified C2 ungroup chondrite whose bulk and organic chemistry compositions have received a considerable attention owing to the short-time exposure before being collected. TL is likely representative of D-type asteroids known to contain complex organic compounds, and was described including aliphatic and aromatic hydrocarbons considered to be building blocks of life (Gilmour 2001; Pizzarello et al. 2001). Recent studies on the spatial distribution and mineralogical association of organics in TL meteorites show a certain affinity of organic compounds for S-bearing phases such as Fe-Ni sulfide coexisting with abundant carbonate (Ca-Mg-Fe-Mn solid solution), magnetite and serpentine (Zega et al. 2010). In particular, carbonate is believed to form from the organic matter during hydrothermal alteration with implications for the carbon (C) isotopic signature. Therefore, the knowledge of how carbonaceous matter survived during the history of a meteorite at extreme pressures-temperatures is of fundamental importance to solve the mystery of the origin of life. In order to investigate the behavior of carbonaceous matter and to constrain the stability and structural evolution of organics and in Tagish Lake meteorite during petrological processes (melting, solid state reaction etc.), we carried heating experiments at 5 GPa and temperature between 800-1400 °C using multi anvil apparatus at GRC, Ehime University. The recovered samples were polished for textural and chemical characterization of the mineral phases using FE-SEM and electron microprobe, respectively. Ultra-thin sections, 80-100 nm thick, were prepared from the recovered samples using focused ion beam. These sections were then transferred to TEM grids for in situ X-ray absorption near-edge spectroscopy (XANES

  13. Chondrites as samples of differentiated planetesimals

    NASA Astrophysics Data System (ADS)

    Elkins-Tanton, Linda; Weiss, Benjamin P.; Zuber, Maria T.

    2010-05-01

    Chondritic meteorites are unmelted, variably metamorphosed samples of the earliest solids of the solar system. A recent paleomagnetic study of CV chondrites suggests that their parent body was internally differentiated and produced a core magnetic dynamo (Carporzen et al., submitted, and this session). Here we show that a parent body that accreted to >250 km in radius by ~1.7 Ma after the formation of CAIs could retain a solid undifferentiated crust overlying a differentiated interior, and would be consistent with formational and evolutionary constraints on the CV parent body. Further, this body could have produced a magnetic field lasting more than 10 Ma. CV chondritic meteorites contain the oldest known solids: calcium-aluminum-rich inclusions (CAIs). The variety of metamorphic textures in ordinary chondrites motivated the "onion shell" model in which chondrites originated at varying depths within a parent body heated primarily by the short-lived radioisotope 26Al, with the highest metamorphic grade originating nearest the center. The large abundances and sizes of CAIs in CV chondrites have long suggested an early parent body accretion age. New Pb-Pb and Al-Mg ages of chondrules in CVs are consistent with the CV parent body having largely completed accretion by the youngest chondrule age of ~1.7-3 Ma. The CV chondrite parent body likely reached peak metamorphic temperatures around 7 to 10 Ma after CAIs, based on I-Xe chronometry for Allende and Mn-Cr chronometry for Mokoia. Bodies that accreted to more than >~20 km radius before ~1.3 to 3 Ma after the formation of CAIs likely contained sufficient 26Al to melt internally from the insulated cumulative effects of radiogenic heating. These early-accreting bodies will melt from the interior out, sometimes forming an interior magma ocean under a solid, conductive, undifferentiated shell. This shell would consist of the same chondritic material that made up the bulk accreting body before melting began. The presence of

  14. Microstructural evidence for a disequilibrium condensation origin for hibonite-spinel inclusions in the ALHA77307 CO3.0 chondrite

    NASA Astrophysics Data System (ADS)

    Han, Jangmi; Brearley, Adrian J.; Keller, Lindsay P.

    2015-12-01

    Two hibonite-spinel inclusions (CAIs 03 and 08) in the ALHA77307 CO3.0 chondrite have been characterized in detail using the focused ion beam sample preparation technique combined with transmission electron microscopy. These hibonite-spinel inclusions are irregularly shaped and porous objects and consist of randomly oriented hibonite laths enclosed by aggregates of spinel with fine-grained perovskite inclusions finally surrounded by a partial rim of diopside. Melilite is an extremely rare phase in this type of CAI and occurs only in one inclusion (CAI 03) as interstitial grains between hibonite laths and on the exterior of the inclusion. The overall petrologic and mineralogical observations suggest that the hibonite-spinel inclusions represent high-temperature condensates from a cooling nebular gas. The textural relationships indicate that hibonite is the first phase to condense, followed by perovskite, spinel, and diopside. Texturally, melilite condensation appears to have occurred after spinel, suggesting that the condensation conditions were far from equilibrium. The crystallographic orientation relationships between hibonite and spinel provide evidence of epitaxial nucleation and growth of spinel on hibonite surfaces, which may have lowered the activation energy for spinel nucleation compared with that of melilite and consequently inhibited melilite condensation. Hibonite contains abundant stacking defects along the (001) plane consisting of different ratios of the spinel and Ca-containing blocks within the ideal hexagonal hibonite structure. This modification of the stacking sequence is likely the result of accommodation of excess Al in the gas into hibonite due to incomplete condensation of corundum from a cooling gas under disequilibrium conditions. We therefore conclude that these two hibonite-spinel inclusions in ALHA77307 formed by high-temperature condensation under disequilibrium conditions.

  15. Calcium isotopic compositions of chondrites

    NASA Astrophysics Data System (ADS)

    Huang, Shichun; Jacobsen, Stein B.

    2017-03-01

    We report mass-dependent and mass-independent Ca isotopic variations in nine chondrites from three groups: carbonaceous, ordinary and enstatite chondrites. There is about 0.25‰ per amu, i.e., ∼1‰ in 44Ca/40Ca, variation in chondrites: carbonaceous chondrites have the lightest Ca isotopes, enstatite chondrites have modeled bulk Earth like Ca isotopes, and ordinary chondrites are in between. The correlations between mass-dependent Ca isotopic variation and chemical variations in chondrites may reflect variable contributions from different endmembers, including refractory inclusions, in different chondrite groups. In detail, enstatite chondrites and the Earth share similar isotopic characteristics, but are very different in chemical compositions. At the ±1 and ±2 ε-unit levels, respectively, there is no measurable 40Ca or 43Ca anomaly in bulk chondrites. Carbonaceous chondrites show several ε-units of 48Ca excess. That is, Ca exhibits both mass-dependent and mass-independent isotopic variations in chondrites, similar to O isotopes. The 48Ca anomaly in bulk chondrites is positively correlated with 50Ti anomaly, but does not form simple correlation with 54Cr anomaly, implying multiple supernova sources for these neutron-rich isotopes in the Solar System. Finally, all meteorites with negative Δ17O have either 48Ca deficits (differentiated meteorites) or 48Ca excess (carbonaceous chondrites), implying that the Sun with a very negative Δ17O is probably also characterized by 48Ca anomaly compared to the Earth. CAIs cannot be taken as representative of the initial isotopic compositions of refractory elements like Ca for the Earth-Moon system.

  16. R Raman Spectroscopy and Petrology of Antarctic CR Chondrites: Comparison with Other Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Komatsu, M.; Fagan, T. J.; Yamaguchi, A.; Mikouchi, T.; Zolensky, M. E.; Yasutake, M.

    2015-01-01

    In Renazzo-like carbonaceous (CR) chondrites, abundant original Fe,Ni-metal is preserved in chrondules, but the matrix is characterized by fine-grained magnetite with phyllosilicate. This combination of reduced Fe in chrodrules with oxidized Fe and phyllosilicate in the matrix has been attributed to aqueous alteration of matrix at relatively low temperatures.

  17. Origins of signalling and memory: matters of life versus death.

    PubMed

    Wheatley, D N; Christensen, S T

    1999-01-01

    This review focuses on the principles in cell-cell communication and cellular ability to respond to external chemical changes which have been so crucial for the development of life on planet Earth. We now know that the capacity of free-living organisms which evolved more than a billion years ago to respond to intercellular signal molecules, originating either from themselves or from other sources in their vicinity, is so similar possibly even more sophisticated - to that of the cells in our own body, and these findings have had a major impact on our struggle to understand how life has evolved and how it can be maintained. Attention is drawn to the very important topic of mechanisms in cell death, being seen as an aggressive and very powerful instrument in the continuance of life and ability of life to proliferate into a plethora of new species, and use insulin-related material as our paradigm. Such signal molecules (hormones) may have played a major role in cellular maintenance throughout evolution.

  18. The Origin of Angular Momentum in Dark Matter Halos

    NASA Astrophysics Data System (ADS)

    Vitvitska, Maya; Klypin, Anatoly A.; Kravtsov, Andrey V.; Wechsler, Risa H.; Primack, Joel R.; Bullock, James S.

    2002-12-01

    We propose a new explanation for the origin of angular momentum in galaxies and their dark halos, in which the halos obtain their spin through the cumulative acquisition of angular momentum from satellite accretion. In our model, the buildup of angular momentum is a random walk process associated with the mass assembly history of the halo's major progenitor. We assume no correlation between the angular momenta of accreted objects. The main role of tidal torques in this approach is to produce the random tangential velocities of merging satellites. Using the extended Press-Schechter approximation, we calculate the growth of mass, angular momentum, and spin parameter λ for many halos. Our random walk model reproduces the key features of the angular momentum of halos found in ΛCDM N-body simulations: a lognormal distribution in λ with an average of <λ>~0.045 and dispersion σλ=0.56, independent of mass and redshift. The evolution of the spin parameter in individual halos in this model is quite different from the steady increase with time of angular momentum in the tidal torque picture. We find both in N-body simulations and in our random walk model that the value of λ changes significantly with time for a halo's major progenitor. It typically has a sharp increase due to major mergers and a steady decline during periods of gradual accretion of small satellites. The model predicts that, on average, the λ of ~1012 Msolar halos that had major mergers after redshift z=3 should be substantially larger than the λ of those that did not. Perhaps surprisingly, this suggests that halos that host later forming elliptical galaxies should rotate faster than halos of spiral galaxies.

  19. Characterization of Presolar Material in the CR Chondrite Northwest Africa 852

    NASA Astrophysics Data System (ADS)

    Leitner, J.; Vollmer, C.; Hoppe, P.; Zipfel, J.

    2012-01-01

    We investigated the inventory of presolar silicate, oxide, and silicon carbide (SiC) grains in the CR2 chondrite Northwest Africa (NWA) 852. Thirty-one O-anomalous grains were detected: 24 were identified as silicates (~78 ppm) the remaining 7 are Al-rich oxides (~38 ppm). NWA 852 is the first C2 chondrite containing O-anomalous presolar dust in concentrations comparable to other more primitive meteorites. Eight presolar SiC grains have been found, representing the highest abundance (~160 ppm) observed so far in primitive meteorites. 15N-enriched matter is also present, although very heterogeneously distributed. Twenty-six of the O-anomalous grains are enriched in 17O, originating from the outflows of low-mass asymptotic giant branch (AGB) stars. We calculate a silicate/oxide abundance ratio of ~2, which indicates a higher degree of aqueous alteration than observed for other presolar-grain-rich meteorites. NWA 852 thus stands between the presolar-grain-rich CR3 chondrites (MET 00426, QUE 99177) and CR2 chondrites with low presolar grain abundances (Renazzo, NWA 530). We calculate an initial presolar silicate abundance of ~800 ppm for NWA 852, if silicate destruction by aqueous alteration is taken into account. Transmission electron microscope (TEM) investigation of one presolar Al-rich grain of an AGB star origin revealed that the grain mainly consists of a single crystal of hibonite with slightly varying orientations. A distinct subgrain (d < 100 nm) with a Ca/Ti ratio of ~1 is located in the central region, most likely indicating a perovskite-like phase. Our data suggest this phase to be a primary condensate and not an alteration product.

  20. CHARACTERIZATION OF PRESOLAR MATERIAL IN THE CR CHONDRITE NORTHWEST AFRICA 852

    SciTech Connect

    Leitner, J.; Hoppe, P.; Vollmer, C.; Zipfel, J.

    2012-01-20

    We investigated the inventory of presolar silicate, oxide, and silicon carbide (SiC) grains in the CR2 chondrite Northwest Africa (NWA) 852. Thirty-one O-anomalous grains were detected: 24 were identified as silicates ({approx}78 ppm); the remaining 7 are Al-rich oxides ({approx}38 ppm). NWA 852 is the first C2 chondrite containing O-anomalous presolar dust in concentrations comparable to other more primitive meteorites. Eight presolar SiC grains have been found, representing the highest abundance ({approx}160 ppm) observed so far in primitive meteorites. {sup 15}N-enriched matter is also present, although very heterogeneously distributed. Twenty-six of the O-anomalous grains are enriched in {sup 17}O, originating from the outflows of low-mass asymptotic giant branch (AGB) stars. We calculate a silicate/oxide abundance ratio of {approx}2, which indicates a higher degree of aqueous alteration than observed for other presolar-grain-rich meteorites. NWA 852 thus stands between the presolar-grain-rich CR3 chondrites (MET 00426, QUE 99177) and CR2 chondrites with low presolar grain abundances (Renazzo, NWA 530). We calculate an initial presolar silicate abundance of {approx}800 ppm for NWA 852, if silicate destruction by aqueous alteration is taken into account. Transmission electron microscope (TEM) investigation of one presolar Al-rich grain of an AGB star origin revealed that the grain mainly consists of a single crystal of hibonite with slightly varying orientations. A distinct subgrain (d < 100 nm) with a Ca/Ti ratio of {approx}1 is located in the central region, most likely indicating a perovskite-like phase. Our data suggest this phase to be a primary condensate and not an alteration product.

  1. Anomalous REE patterns in unequilibrated enstatite chondrites: Evidence and implications

    NASA Technical Reports Server (NTRS)

    Crozaz, Ghislaine; Hsu, Weibiao

    1993-01-01

    We present here a study of Rare Earth Element (REE) microdistributions in unequilibrated enstatite chondrites (EOC's). Although the whole rock REE contents are similar in both unequilibrated and equilibrated chondrites, the host minerals of these refractory elements are different. In the least equilibrated ordinary chondrites (UOC's), the REE reside mainly in glass whereas, in their more equilibrated counterparts, the bulk of the REE is in calcium phosphate, a metamorphic mineral that formed by oxidation of phosphorous originally contained in metal. In the smaller group of enstatite (E) chondrites, calcium phosphate is absent and the phase that contains the highest REE concentrations is a minor mineral, CaS (oldhamite), which contains approximately 50 percent of the total Ca present. In E chondrites, elements typically considered to be lithophiles (such as Ca and Mn) occur in sulfides rather than silicates. This indicates formation under extremely reducing conditions, thus in a region of the solar nebula distinct from those that supplied the more abundant ordinary and carbonaceous chondrites. Previously, we observed a variety of REE patterns in the oldhamite of UEC's; they range from almost flat to some with pronounced positive Eu and Yb anomalies. Here, we searched for complementary REE patterns in other minerals from E chondrites and found them in the major mineral, enstatite. Whenever Eu and Yb anomalies are present in this mineral, they are always negative.

  2. Highly siderophile elements in chondrites

    USGS Publications Warehouse

    Horan, M.F.; Walker, R.J.; Morgan, J.W.; Grossman, J.N.; Rubin, A.E.

    2003-01-01

    The abundances of the highly siderophile elements (HSE), Re, Os, Ir, Ru, Pt and Pd, were determined by isotope dilution mass spectrometry for bulk samples of 13 carbonaceous chondrites, 13 ordinary chondrites and 9 enstatite chondrites. These data are coupled with corresponding 187Re-187Os isotopic data reported by Walker et al. [Geochim. Cosmochim. Acta, 2002] in order to constrain the nature and timing of chemical fractionation relating to these elements in the early solar system. The suite of chondrites examined displays considerable variations in absolute abundances of the HSE, and in the ratios of certain HSE. Absolute abundances of the HSE vary by nearly a factor of 80 among the chondrite groups, although most vary within a factor of only 2. Variations in concentration largely reflect heterogeneities in the sample aliquants. Different aliquants of the same chondrite may contain variable proportions of metal and/or refractory inclusions that are HSE-rich, and sulfides that are HSE-poor. The relatively low concentrations of the HSE in CI1 chondrites likely reflect dilution by the presence of volatile components. Carbonaceous chondrites have Re/Os ratios that are, on average, approximately 8% lower than ratios for ordinary and enstatite chondrites. This is also reflected in 187Os/188Os ratios that are approximately 3% lower for carbonaceous chondrites than for ordinary and enstatite chondrites. Given the similarly refractory natures of Re and Os, this fractionation may have occurred within a narrow range of high temperatures, during condensation of these elements from the solar nebula. Superimposed on this major fractionation are more modest movements of Re or Os that occurred within the last 0-2 Ga, as indicated by minor open-system behavior of the Re-Os isotope systematics of some chondrites. The relative abundances of other HSE can also be used to discriminate among the major classes of chondrites. For example, in comparison to the enstatite chondrites

  3. Interstellar chemistry recorded in organic matter from primitive meteorites.

    PubMed

    Busemann, Henner; Young, Andrea F; Alexander, Conel M O'd; Hoppe, Peter; Mukhopadhyay, Sujoy; Nittler, Larry R

    2006-05-05

    Organic matter in extraterrestrial materials has isotopic anomalies in hydrogen and nitrogen that suggest an origin in the presolar molecular cloud or perhaps in the protoplanetary disk. Interplanetary dust particles are generally regarded as the most primitive solar system matter available, in part because until recently they exhibited the most extreme isotope anomalies. However, we show that hydrogen and nitrogen isotopic compositions in carbonaceous chondrite organic matter reach and even exceed those found in interplanetary dust particles. Hence, both meteorites (originating from the asteroid belt) and interplanetary dust particles (possibly from comets) preserve primitive organics that were a component of the original building blocks of the solar system.

  4. Chondrule-matrix relationships in chondritic meteorites

    NASA Technical Reports Server (NTRS)

    Brearley, A. J.

    1994-01-01

    The relationship between chondrules and matrix (fine grained material with a grain size less than 5 micrometers) in chondritic meteorites has been the subject of considerable controversy and no consensus currently exists. The coexistence of these two components in meteorites with bulk compositions that deviate only slightly from CI abundances suggests that cosmochemically their origins are closely linked. Any consideration of the relationship between chondrules and matrix hinges to a large degree on the origin of matrix. The entire spectrum of models exists from matrix as a nebular product to derivation entirely from chondrules. Early models of solar nebular evolution viewed chondrites as a two-component mixture of high- and low-temperature condensates. However, this model has been challenged by the recognition that the nebula was probably not uniformly vaporized.

  5. Search for Organic Nanoglobules in Carbonaceous Chondrites Using Microtomography

    NASA Technical Reports Server (NTRS)

    Matsumoto, T.; Tsuchiyama, A.; Nakamura-Messenger, K.; Zolensky, M. E.; Nakano, T.; Uesugi, K.

    2010-01-01

    Primitive solar materials have various organic matters. In recent years, novel organic materials called organic nanoglobules of a few hundred micrometers in typical size were discovered in carbonaceous chondrites, IDPs, and comet 81P/Wild 2. The organic globules are spherical shape and in many cases with hollow structures. Composition of the globules are mainly aromatic carbon. The isotopic anomalies of SD and 6N 15 observed in the globules indicate that they were formed from photochemical reaction to ice particles at very low temperature environment, such as molecular clouds or outer protosolar disk. Aqueous alteration of organic matters and the gamma-ray irradiation to PAH are also suggested as alternative possible formation processes. If the globules are made from organic ice particles, the hollow regions of the globules are suggested to be once filled with volatile H20-rich organic ices, while if they were formed by aqueous alteration, the hollow regions should be filled with a fluid which caused the aqueous alteration. However, fluids in the globules have not been detected so far in the previous studies. If fluids were originally preserved in the hollows, they might be lost during destructive processes of sample separation or preparation for TEM observation. X-ray computed tomography (CT) is a nondestructive method which can determine 3-D internal structures of objects. SR (synchrotron radiation)-based imaging microtomography can give submicron spatial resolution [8] and was applied to micro textures in extraterrestrial materials, such as cometary grains captured by the Stardust mission [9]. If organic globules are observed non-destructively in carbonaceous chondrites by tomography, we can check the presence of fluids in the hollows. If fluids are preserved, we may analyze chemical and isotopic compositions of the fluids. The purpose of this study is to observe organic nanoglobules using imaging tomography for future analysis.

  6. Shock metamorphism of carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Scott, Edward R. D.; Keil, Klaus; Stoeffler, Dieter

    1992-01-01

    Shock effects were studied in 69 carbonaceous chondrites, including CM2, CO3, CV3, ungrouped C2-C4, and CK4-6 chondrites, using optical microscopy of thin sections. It is shown that the classification scheme of Stoeffler et al. (1991) for the progressive stages of shock metamorphism in ordinary chondrites is also applicable to carbonaceous chondrites. On the basis of shock effects in olivine, the 69 carbonaceous chondrites could be assigned to four shock stage, S1 to S4. The CM2 and CO3 groups were found to be the least shocked chondrite groups, whereas the CK4-6 and CV3 were the most strongly shocked groups.

  7. Organic Analysis in the Miller Range 090657 CR2 Chondrite: Part 3 C and N Isotopic Imaging

    NASA Technical Reports Server (NTRS)

    Messenger, S.; Nakamura-Messenger, K.; Elsila, J. E.; Berger, E. L.; Burton, A. S.; Clemett, S. J.; Cao, T.

    2016-01-01

    Primitive carbonaceous chondrites contain a wide variety of organic material, ranging from soluble discrete molecules to insoluble nanoglobules of macro-molecular carbon. The relationship between the soluble organic molecules, macromolecular organic material, and host minerals are poorly understood. Large H, C and N isotopic anomalies suggest some organic components formed in low-T interstellar or outer Solar System environments. The highest isotope anomalies occur in m-scale inclusions in the most primitive materials, such as cometary dust and the least altered carbonaceous chondrites. Often, the hosts of these isotopically anomalous 'hotspots' are discrete organic nanoglobules that probably formed in the outermost reaches of the protosolar disk or cold molecular cloud. Molecular and isotopic studies of meteoritic organic matter are aimed at identifying the chemical properties and formation processes of interstellar organic materials and the subsequent chemical evolutionary pathways in various Solar System environments. The combination of soluble and insoluble analyses with in situ and bulk studies provides powerful constraints on the origin and evolution of organic matter in the Solar System. Using macroscale extraction and analysis techniques as well as microscale in situ observations we have been studying both insoluble and soluble organic material in primitive astromaterial samples. Here, we present results of bulk C and N isotopic measurements and coordinated in situ C and N isotopic imaging and mineralogical and textural studies of carbonaceous materials in a Cr2 carbonaceous chondrite. In accompanying abstracts we discuss the morphology and distribution of carbonaceous components and soluble organic species of this meteorite.

  8. Carbon in the matrices of ordinary chondrites

    NASA Astrophysics Data System (ADS)

    Makjanic, J.; Vis, R. D.; Hovenier, J. W.; Heymann, D.

    1993-03-01

    Carbon in the petrologic matrices of a number of ordinary chondrites of groups H, L, and LL, and of types 3 through 6 was studied with a nuclear microprobe and a Raman microprobe. The majority of the matrices had carbon contents in the narrow range between 0.03 and 0.2 wt pct. The carbon content decreased only slightly with increasing petrologic type. Carbon-rich coats around troilite and/or metal phases occurred in five meteorites. Poorly ordered carbon was found in the matrices. The carbon in the meteorites of higher petrologic types was slightly better ordered than in the meteorites of lower types. The narrow range of carbon contents and the similarity of the structural form of carbon in the matrices of the measured ordinary chondrites, which represent all groups and types, imply that their matrices may contain a common component, which might be of interstellar origin.

  9. Ion microprobe magnesium isotope analysis of plagioclase and hibonite from ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Hinton, R. W.; Bischoff, A.

    1984-01-01

    Ion and electron microprobes were used to examine Mg-26 excesses from Al-26 decay in four Al-rich objects from the type 3 ordinary hibonite clast in the Dhajala chondrite. The initial Al-26/Al-27 ratio was actually significantly lower than Al-rich inclusions in carbonaceous chondrites. Also, no Mg-26 excesses were found in three plagioclase-bearing chondrules that were also examined. The Mg-26 excesses in the hibonite chondrites indicated a common origin for chondrites with the excesses. The implied Al-26 content in a proposed parent body could not, however, be confirmed as a widespread heat source in the early solar system.

  10. Oxygen isotopic abundances in calcium- aluminum-rich inclusions from ordinary chondrites: implications for nebular heterogeneity.

    PubMed

    McKeegan, K D; Leshin, L A; Russell, S S; MacPherson, G J

    1998-04-17

    The oxygen isotopic compositions of two calcium-aluminum-rich inclusions (CAIs) from the unequilibrated ordinary chondrite meteorites Quinyambie and Semarkona are enriched in 16O by an amount similar to that in CAIs from carbonaceous chondrites. This may indicate that most CAIs formed in a restricted region of the solar nebula and were then unevenly distributed throughout the various chondrite accretion regions. The Semarkona CAI is isotopically homogeneous and contains highly 16O-enriched melilite, supporting the hypothesis that all CAI minerals were originally 16O-rich, but that in most carbonaceous chondrite inclusions some minerals exchanged oxygen isotopes with an external reservoir following crystallization.

  11. Porphyritic Olivine-Pyroxene Clast in Kaidun: First Discovery of an Ordinary Chondrite Clast?

    NASA Technical Reports Server (NTRS)

    Mikouchi, T.; Makishima, J.; Koizumi, E.; Zolensky, M. E.

    2005-01-01

    Kaidun is an enigmatic meteorite showing a micro-brecciated texture composed of variable kinds of lithic clasts and mineral fragments. The constituent components range from primitive chondritic materials to differentiated achondritic materials, and thus believed to have originated from a large parent body accumulating materials from many different bodies in the asteroid belt. One of the interesting observations is that no ordinary chondrite component has been found yet, although C and E chondrites components are abundant. In this abstract, we report mineralogy of the clast (Kaidun #15415- 01.3.13a) showing a porphyritic olivine-pyroxene chondrule-like texture similar to those found in unequilibrated ordinary chondrites.

  12. Metastable carbon in two chondritic porous interplanetary dust particles

    NASA Technical Reports Server (NTRS)

    Rietmeijer, F. J. M.; Mackinnon, I. D. R.

    1986-01-01

    An understanding of carbonaceous matter in primitive extraterrestrial materials is an essential component of studies on dust evolution in the interstellar medium and the early history of the Solar System. Analytical Electron Microscopy (AEM) on carbonaceous material in two Chondritic Porous (CP) aggregrates is presented. The study suggests that a record of hydrocarbon carbonization may also be preserved in these materials.

  13. The Galatia, Kansas, chondrite

    NASA Technical Reports Server (NTRS)

    Van Schmus, W. R.; Keil, K.; Lange, D. E.; Conrad, G. H.

    1978-01-01

    The paper describes the Galatia meteorite found August 1971 approximately 7 km ENE of Galatia, Barton County, Kansas (98 deg 53 min W, 38 deg 39.5 min N). The single stone weighed 23.9 kg and is partially weathered. Olivine (Fa 24.9) and pyroxene (Fs 20.9) compositions indicate L-group classification, and textural observations indicate that the stone is of petrologic type 6. While Galatia is similar in many respects to the Otis L6 chondrite found 20 miles to the west, Galatia does not have the brecciated structure of Otis and is therefore not part of the same fall.

  14. An evaluation of the origin and post-depositional modification of coal mineral matter using rare earth elements and neodymium isotopes

    NASA Astrophysics Data System (ADS)

    Schatzel, Steven Joseph

    2001-07-01

    This study was conducted in western Pennsylvania on the Lower Kittanning Coal bed to address the issue of coal mineral matter origin and depositional environment. Channel samples of the coal, the underlying clay (paleosol) unit, and the overlying shale were retrieved over a 170 km east-west range of sampling sites. Analytical techniques applied to the samples include the megascopic description of coal lithotypes, proximate and ultimate analysis, inductively coupled plasma atomic emission spectroscopy (ICP-AES), coal petrography, instrumental neutron activation analysis (INAA), and thermal ionization mass spectrometry (TIMS). Major cation concentrations in the coal are generally consistent with depositional environment interpretations made on the overlying shale (e.g., epigenetic mineralization). Titanium and shale overburden-normalized plots of the major cation data show that the coal bed is enriched in Fe and Ca compared to the overlying shale. Magnesium, sodium and potassium were depleted in the coal relative to the shale. Rare earth element (REE) concentrations and neodymium (Nd) isotopes were used to identify sources of coal mineral matter and processes of alteration. A high degree of similarity exists between chondrite normalized REE plots of the coal, the shale overburden and the North American Shale Composite. The Nd isotopic data from the Lower Kittanning Coal bed show a range of epsilonNd(t) (at time of deposition) from -8.4 to -9.9 at the study sites. The Nd isotopic data from the overlying shale and the underlying clay unit show a range from epsilonNd(t) values = -8.2 to -10.2. These data are interpreted to indicate a single mineral source throughout the deposition of all three units. That source appears to be clastic matter derived the Appalachian Mountains. An isochron-style plot of the isotopic data appears to indicate Sm-Nd fractionation occurred at the approximate age of the coal bed. This is interpreted as evidence of mobilization of the Sm and Nd

  15. Crustal structure and igneous processes in a chondritic Io

    NASA Technical Reports Server (NTRS)

    Kargel, J. S.

    1993-01-01

    Liquid sulfur can form when metal-free C1 or C2 chondrites are heated. It may be obtained either by direct melting of native sulfur in disequilibrated C1 or C2 chondrites or by incongruent melting of pyrite and other sulfides in thermodynamically equilibrated rocks of the same composition. Hence, Lewis considered C2 chondrites to be the best meteoritic analog for Io's bulk composition. Metal-bearing C3 and ordinary chondrites are too chemically reduced to yield liquid sulfur and are not thought to represent plausible analogs of Io's bulk composition. An important aspect of Lewis' work is that CaSO4 and MgSO4 are predicted to be important in Io. Real C1 and C2 chondrites contain averages of, respectively, 11 percent and 3 percent by mass of salts (plus water of hydration). The most abundant chondritic salts are magnesium and calcium sulfates, but other important components include sulfates of sodium, potassium, and nickel and carbonates of magnesium, calcium, and iron. It is widely accepted that chondritic salts are formed by low-temperature aqueous alteration. Even if Io originally did not contain salts, it is likely that aqueous alteration would have yielded several percent sulfates and carbonates. In any event, Io probably contains sulfates and carbonates. This report presents the results of a model of differentiation of a simplified C2 chondrite-like composition that includes 1.92 percent MgSO4, 0.56 percent CaSO4, 0.53 percent CaCO3, and 0.094 percent elemental sulfur. The temperature of the model is gradually increased; ensuing fractional melting results in these components extruding or intruding at gravitationally stable levels in Io's crust. Relevant phase equilibria were reviewed. A deficiency of high-pressure phase equilibria renders the present model qualitative.

  16. Mineralogy and Petrology of Yamato 86029: A New Type of Carbonaceous Chondrite

    NASA Technical Reports Server (NTRS)

    Tonui, E.; Zolensky, M. E.

    2001-01-01

    Y-86029 resembles CI chondrites. Its matrix is very fine-grained. Olivine shows evidence of shock, which has rarely been observed in carbonaceous chondrites. Y-86029 experienced aqueous and thermal alteration during or after accretion in parent body. Additional information is contained in the original extended abstract.

  17. Role of effluent organic matter in the photochemical degradation of compounds of wastewater origin.

    PubMed

    Bodhipaksha, Laleen C; Sharpless, Charles M; Chin, Yu-Ping; MacKay, Allison A

    2017-03-01

    The photoreactivity of treated wastewater effluent organic matter differs from that of natural organic matter, and the indirect phototransformation rates of micropollutants originating in wastewater are expected to depend on the fractional contribution of wastewater to total stream flow. Photodegradation rates of four common compounds of wastewater origin (sulfamethoxazole, sulfadimethoxine, cimetidine and caffeine) were measured in river water, treated municipal wastewater effluent and mixtures of both to simulate various effluent-stream water mixing conditions that could occur in environmental systems. Compounds were chosen for their unique photodegradation pathways with the photochemically produced reactive intermediates, triplet-state excited organic matter ((3)OM*), singlet oxygen ((1)O2), and hydroxyl radicals (OH). For all compounds, higher rates of photodegradation were observed in effluent relative to upstream river water. Sulfamethoxazole degraded primarily via direct photolysis, with some contribution from OH and possibly from carbonate radicals and other unidentified reactive intermediates in effluent-containing samples. Sulfadimethoxine also degraded mainly by direct photolysis, and natural organic matter appeared to inhibit this process to a greater extent than predicted by light screening. In the presence of effluent organic matter, sulfadimethoxine showed additional reactions with OH and (1)O2. In all water samples, cimetidine degraded by reaction with (1)O2 (>95%) and caffeine by reaction with OH (>95%). In river water mixtures, photodegradation rate constants for all compounds increased with increasing fractions of effluent. A conservative mixing model was able to predict reaction rate constants in the case of hydroxyl radical reactions, but it overestimated rate constants in the case of (3)OM* and (1)O2 pathways. Finally, compound degradation rate constants normalized to the rate of light absorption by water correlated with E2/E3 ratios (sample

  18. The compositional classification of chondrites: VII. The R chondrite group

    NASA Astrophysics Data System (ADS)

    Kallemeyn, Gregory W.; Rubin, Alan E.; Wasson, John T.

    1996-06-01

    Bulk compositional and petrographic data clearly define the new R (Rumuruti) group of chondrites consisting of Rumuruti (the only fall), ALH85151, Acfer 217, Carlisle Lakes, Dar al Gani 013, PCA91002, PCA91241, Y-75302, Y-793575, and Y-82002. Compositional, petrographic, rare-gas, and 0-isotopic data strongly suggest that PCA91002 and PCA91241 are paired. The Yamato specimens are probably not paired. The matrices of the known R chondrites have experienced similar, minor degrees of metamorphism; petrographic types are 3.8-3.9 with the exception of ALH85151, 3.6. All except Carlisle Lakes contain equilibrated (R5-R6) clasts. Petrographically, the R chondrites are characterized by a low chondrule/matrix modal abundance ratio, high states of oxidation (reflected by abundant NiO-bearing olivine with Fa37-40), relatively small chondrules (mean apparent diameters of ˜400 μ) abundant (up to ˜11 wt%) sulfides (mainly pyrrhotite and pentlandite), and negligible amounts of metallic Fe-Ni. Refractory lithophile abundances are ˜0.95 X Cl, intermediate between those in ordinary chondrites (OC) and CI chondrites. Abundances of the volatile elements Se and Zn are greatly enhanced relative to OC. The R chondrites are clearly distinguished from other chondrite groups on the basis of Al/Mn and Zn/Mn abundance ratios. The oxygen isotopic data plot roughly along a slope- 1/2 line, with whole-rock Δ17O values higher than for any other chondrite group. Rumuruti, Acfer 217, ALH85151, PCA91002, and PCA91241 have light/ dark structures and solar-wind-implanted rare gases indicating that they are regolith breccias. The Yamato specimens also have light/dark structures and are inferred to be regolith breccias. Carlisle Lakes lacks solar rare gases and is unbrecciated. Based on similarities in refractory lithophile abundances 00.95 X CI), oxygen isotope compositions ( Δ17O ≥ 0), and refractory inclusion abundances (<0.1 vol%;none have been reported), the R chondrites probably belong to

  19. The stability of hibonite, melilite and other aluminous phases in silicate melts: Implications for the origin of hibonite-bearing inclusions from carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Beckett, J. R.; Stolper, E.

    1994-01-01

    Phase fields in which hibonite and silicate melt coexist with spinel CaAl4O7, gehlenitic melilite, anorthite or corundum at 1 bar in the system CaO-MgO-Al2O3-SiO2-TiO2 were determined. The hibonites contain up to 1.7 wt% SiO2. For TiO2, the experimentally determined partition coefficients between hibonite and coexisting melt D(sub i)(sup Hib/L), vary from 0.8 to 2.1 and generally decrease with increasing TiO2 in the liquid. Based on Ti partitioning between hibonite and melt, bulk inclusion compositions and hibonite-saturated liquidus phase diagrams, the hibonite in hibonite-poor fluffy Type A inclusions from Allende and at least some hibonite from hibonite-rich inclusions is relict, although much of the hibonite from hibonite-glass spherules probably crystallized metasably from a melt. Bulk compositions for all of these CAIs are consistent with an origin as melite + hibonite + spinel + perovskite phase assembalges that were partially altered and in some cases partially or completely melted. The duration of the melting event was sufficient to remove any Na introduced by the alteration process but frequently insufficient to dissolve all of the original hibonite. Simple thermochemical models developed for meteoritic melilite and hibonite solid solutions were used to obtain equilibration temperatures of hibonite-bearing phase assemblages with vapor. Referenced to 10(exp -3) atm, hibonite + corundum + vapor equilibrated at approximately 1260 C and hibonite + spinel +/- melilite + vapor at 1215 +/- 10 C. If these temperatures reflect condensation in a cooling gas of solar composition, then hibonite +/- corundum condensed first, followed by spinel and then melilite. The position of perovskite within this sequence is uncertain, but it probably began to condense before spinel. This sequence of phase appearances and relative temperatures is generally consistent with observed textures but differs from expectations based on classical condensation calculations in that

  20. The stability of hibonite, melilite and other aluminous phases in silicate melts: Implications for the origin of hibonite-bearing inclusions from carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Beckett, J. R.; Stolper, E.

    1994-01-01

    Phase fields in which hibonite and silicate melt coexist with spinel CaAl4O7, gehlenitic melilite, anorthite or corundum at 1 bar in the system CaO-MgO-Al2O3-SiO2-TiO2 were determined. The hibonites contain up to 1.7 wt% SiO2. For TiO2, the experimentally determined partition coefficients between hibonite and coexisting melt D(sub i)(sup Hib/L), vary from 0.8 to 2.1 and generally decrease with increasing TiO2 in the liquid. Based on Ti partitioning between hibonite and melt, bulk inclusion compositions and hibonite-saturated liquidus phase diagrams, the hibonite in hibonite-poor fluffy Type A inclusions from Allende and at least some hibonite from hibonite-rich inclusions is relict, although much of the hibonite from hibonite-glass spherules probably crystallized metasably from a melt. Bulk compositions for all of these CAIs are consistent with an origin as melite + hibonite + spinel + perovskite phase assembalges that were partially altered and in some cases partially or completely melted. The duration of the melting event was sufficient to remove any Na introduced by the alteration process but frequently insufficient to dissolve all of the original hibonite. Simple thermochemical models developed for meteoritic melilite and hibonite solid solutions were used to obtain equilibration temperatures of hibonite-bearing phase assemblages with vapor. Referenced to 10(exp -3) atm, hibonite + corundum + vapor equilibrated at approximately 1260 C and hibonite + spinel +/- melilite + vapor at 1215 +/- 10 C. If these temperatures reflect condensation in a cooling gas of solar composition, then hibonite +/- corundum condensed first, followed by spinel and then melilite. The position of perovskite within this sequence is uncertain, but it probably began to condense before spinel. This sequence of phase appearances and relative temperatures is generally consistent with observed textures but differs from expectations based on classical condensation calculations in that

  1. The stability of hibonite, melilite and other aluminous phases in silicate melts: Implications for the origin of hibonite-bearing inclusions from carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Beckett, J. R.; Stolper, E.

    1994-01-01

    Phase fields in which hibonite and silicate melt coexist with spinel CaAl4O7, gehlenitic melilite, anorthite or corundum at 1 bar in the system CaO-MgO-Al2O3-SiO2-TiO2 were determined. The hibonites contain up to 1.7 wt% SiO2. For TiO2, the experimentally determined partition coefficients between hibonite and coexisting melt DiHib/L, vary from 0.8 to 2.1 and generally decrease with increasing TiO2 in the liquid. Based on Ti partitioning between hibonite and melt, bulk inclusion compositions and hibonite-saturated liquidus phase diagrams, the hibonite in hibonite-poor fluffy Type A inclusions from Allende and at least some hibonite from hibonite-rich inclusions is relict, although much of the hibonite from hibonite-glass spherules probably crystallized metasably from a melt. Bulk compositions for all of these CAIs are consistent with an origin as melite + hibonite + spinel + perovskite phase assemblages that were partially altered and in some cases partially or completely melted. The duration of the melting event was sufficient to remove any Na introduced by the alteration process but frequently insufficient to dissolve all of the original hibonite. Simple thermochemical models developed for meteoritic melilite and hibonite solid solutions were used to obtain equilibration temperatures of hibonite-bearing phase assemblages with vapor. Referenced to 10-3 atm, hibonite + corundum + vapor equilibrated at approximately 1260 C and hibonite + spinel +/- melilite + vapor at 1215 +/- 10 C. If these temperatures reflect condensation in a cooling gas of solar composition, then hibonite +/- corundum condensed first, followed by spinel and then melilite. The position of perovskite within this sequence is uncertain, but it probably began to condense before spinel. This sequence of phase appearances and relative temperatures is generally consistent with observed textures but differs from expectations based on classical condensation calculations in that equilibration temperatures

  2. Morphological Study of Insoluble Organic Matter Residues from Primitive

    NASA Technical Reports Server (NTRS)

    Changela, H. G.; Stroud, R. M.; Peeters, Z.; Nittler, L. R.; Alexander, C. M. O'D.; DeGregorio, B. T.; Cody, G. D.

    2012-01-01

    Insoluble organic matter (IOM) constitutes a major proportion, 70-99%, of the total organic carbon found in primitive chondrites [1, 2]. One characteristic morphological component of IOM is nanoglobules [3, 4]. Some nanoglobules exhibit large N-15 and D enrichments relative to solar values, indicating that they likely originated in the ISM or the outskirts of the protoplanetary disk [3]. A recent study of samples from the Tagish Lake meteorite with varying levels of hydrothermal alteration suggest that nanoglobule abundance decreases with increasing hydrothermal alteration [5]. The aim of this study is to further document the morphologies of IOM from a range of primitive chondrites in order to determine any correlation of morphology with petrographic grade and chondrite class that could constrain the formation and/or alteration mechanisms.

  3. Assemblage of Presolar Materials and Early Solar System Condensates in Chondritic Porous Interplanetary Dust Particles

    NASA Technical Reports Server (NTRS)

    Nguyen, A. N.; Nakamura-Messenger, K.; Messenger, S.; Keller, L. P.; Kloeck, W.

    2015-01-01

    Anhydrous chondritic porous inter-planetary dust particles (CP IDPs) contain an assortment of highly primitive solar system components, molecular cloud matter, and presolar grains. These IDPs have largely escaped parent body processing that has affected meteorites, advocating cometary origins. Though the stardust abundance in CP IDPs is generally greater than in primitive meteorites, it can vary widely among individual CP IDPs. The average abundance of silicate stardust among isotopically primitive IDPs is approx. 375 ppm while some have extreme abundances up to approx. 1.5%. H and N isotopic anomalies are common in CP IDPs and the carrier of these anomalies has been traced to organic matter that has experienced chemical reactions in cold molecular clouds or the outer protosolar disk. Significant variations in these anomalies may reflect different degrees of nebular processing. Refractory inclusions are commonly observed in carbonaceous chondrites. These inclusions are among the first solar system condensates and display 16O-rich isotopic compositions. Refractory grains have also been observed in the comet 81P/Wild-2 samples re-turned from the Stardust Mission and in CP IDPs, but they occur with much less frequency. Here we conduct coordinated mineralogical and isotopic analyses of CP IDPs that were characterized for their bulk chemistry by to study the distribution of primitive components and the degree of nebular alteration incurred.

  4. A New Modal Analysis Method to put Constraints on the Aqueous Alteration of CR Chondrites and Estimate the Unaltered CR Composition

    NASA Technical Reports Server (NTRS)

    Perronnet, M.; Zolensky, M. E.; Gounelle, M.; Schwandt, C. S.

    2007-01-01

    carbonaceous chondrites are of the major interest since they contain one of the most primitive organic matters. However, aqueous alteration has more or less overprinted their original features in a way that needed to be assessed. That was done in the present study by comparing the mineralogy of the most altered CR1 chondrite, GRO 95577, to a less altered CR2, Renazzo. Their modal analyses were achieved thanks to a new method, based on X-ray elemental maps acquired on electron microprobe, and on IDL image treatment. It allowed the collection of new data on the composition of Renazzo and confirmed the classification of GRO 95577 as a CR1. New alteration products for CRs, vermiculite and clinochlore, were observed. The homogeneity of the Fe-poor clays in the CR1 and the distinctive matrix composition in the two chondrites suggest a wide-range of aqueous alteration on CRs. The preservation of the outlines of the chondrules in GRO 95577 and the elemental transfers of Al, Fe and Ca throughout the chondrule and of Fe and S from the matrix to the chondrule favor the idea of an asteroidal location of the aqueous alteration. From their mineralogical descriptions and modal abundances, the element repartitions in Renazzo and GRO 95577 were computed. It indicates a possible relationship between these two chondrites via an isochemical alteration process. Knowing the chemical reactions that occurred during the alteration, it was thus possible to decipher the mineralogical modal abundances in the unaltered CR body.

  5. A New Modal Analysis Method to put Constraints on the Aqueous Alteration of CR Chondrites and Estimate the Unaltered CR Composition

    NASA Technical Reports Server (NTRS)

    Perronnet, M.; Zolensky, M. E.; Gounelle, M.; Schwandt, C. S.

    2007-01-01

    CR carbonaceous chondrites are of the major interest since they contain one of the most primitive organic matters. However, aqueous alteration has more or less overprinted their original features in a way that needed to be assessed. That was done in the present study by comparing the mineralogy of the most altered CR1 chondrite, GRO 95577, to a less altered CR2, Renazzo. Their modal analyses were achieved thanks to a new method, based on X-ray elemental maps acquired on electron microprobe, and on IDL image treatment. It allowed the collection of new data on the composition of Renazzo and confirmed the classification of GRO 95577 as a CR1. New alteration products for CRs, vermiculite and clinochlore, were observed. The homogeneity of the Fe-poor clays in the CR1 and the distinctive matrix composition in the two chondrites suggest a wide-range of aqueous alteration on CRs. The preservation of the outlines of the chondrules in GRO 95577 and the elemental transfers of Al, Fe and Ca throughout the chondrule and of Fe and S from the matrix to the chondrule favor the idea of an asteroidal location of the aqueous alteration. From their mineralogical descriptions and modal abundances, the element repartitions in Renazzo and GRO 95577 were computed. It indicates a possible relationship between these two chondrites via an isochemical alteration process. Knowing the chemical reactions that occurred during the alteration, it was thus possible to decipher the mineralogical modal abundances in the unaltered CR body.

  6. LEW 87223: A Unique E Chondrite with Possible Links to H Chondrites

    NASA Astrophysics Data System (ADS)

    Grossman, J. N.; MacPherson, G. J.; Crozaz, G.

    1993-07-01

    , all of which partially replace ferroan pyroxene ^FS(sub)15-18). All of these features are consistent with a history involving strong reduction, shock, and heating. We analyzed four large, unweathered oldhamite grains in LEW87220 and 87234 by ion probe, and found trace element characteristics similar to those seen in MAC88136, the only known EL3 chondrite [3]: Mg, Sr, and Zr are lower, and Mn is higher than in EH oldhamite. One grain has a REE pattem that is flat at 60 x CI for LREE, and decreases from 46 x CI at Eu to 15 x CI at Lu, with a positive Yb anomaly (Yb/Yb*=3). The other grains have flat REE patterns near 75 x CI, with negative Eu anomalies (Eu/Eu*=0.4). The first pattern is most likely nebular in origin. The second, more common pattern, with the negative Eu anomaly is unlikely to be nebular, and may be metamorphic in origin, in which case the meteorite contains a mixture of nebular and metamorphic oldhamite. Zhang et al. [2] explained the low abundances of alkalis, Mn, Ga, and Se, and high abundance of siderophiles in LEW87223 as being due to the addition of EL metal, and removal of sulfides during shock and thermal processing of a normal EL3. This seems highly implausible to us because of the physical difficulty of completely separating minor sulfides from FeS and metal, and because perryite, which is intimately associated with metal in E chondrites, is missing. It is more likely that the chondrite represents an entirely new group of E chondrites. The high abundance (10s of %) of blackened (reduced) chondrules also indicates a population of chondrules that was initially quite oxidized; in fact, the measured compositions of surviving ferroan pyroxene are in the H-chondrite range. Also evident in the published trace element data [2] is a siderophile element abundance pattern identical to that in H chondrites but different from those in EH and EL chondrites. LEW87223 may be a link between the ordinary and enstatite chondrite groups. References: [1] Mason

  7. Physical propoerties of incompletely compacted equilibrated ordinary chondrites: Implications for asteroidal structure and impact processing

    SciTech Connect

    Sasso, M.R.; Macke, R.J.; Britt, D.T.; Rivers, M.L.; Ebel, D.S.; Friedrich, J.M.

    2009-03-19

    Aside from robotic exploration, meteorites are our primary source of information about the asteroids that they sample. Although there are some discrepancies, there are dynamical, spectral, and compositional evidence for an S-type asteroid connection to the ordinary chondrite meteorites. Reconciling the measured bulk density of chondrites with that of asteroids can yield important inferences about the internal structure of asteroids. For example, the bulk density of S-type asteroids is typically much less than the bulk density of chondrites, leading to the inference that asteroids contain a significant quantity of macroporosity. We have identified several unusual ordinary chondrites that have been incompletely compacted relative to petrologically similar but much less porous chondrites. Although these are equilibrated chondrites, they have extreme amounts of pore spaces between mineral grains. Here, we detail our efforts quantifying the nature of the pore spaces in these chondrites and we examine the implications for the structure and mechanical processing of the asteroids from which these chondrites originate. Our pore size distribution data may also provide constraints for the modeling of heat flow and shock waves within primordial chondritic parent bodies.

  8. Workshop on Parent-Body and Nebular Modification of Chondritic Materials

    NASA Technical Reports Server (NTRS)

    Zolensky, M. E. (Editor); Krot, A. N. (Editor); Scott, E. R. D. (Editor)

    1997-01-01

    Topics considered include: thermal Metamorphosed Antarctic CM and CI Carbonaceous Chondrites in Japanese Collections, and Transformation Processes of Phyllosilicates; use of Oxygen Isotopes to Constrain the Nebular and Asteroidal Modification of Chondritic Materials; effect of Revised Nebular Water Distribution on Enstatite Chondrite Formation; interstellar Hydroxyls in Meteoritic Chondrules: Implications for the Origin of Water in the Inner Solar System; theoretical Models and Experimental Studies of Gas-Grain Chemistry in the Solar Nebula; chemical Alteration of Chondrules on Parent Bodies; thermal Quenching of Silicate Grains in Protostellar Sources; an Experimental Study of Magnetite Formation in the Solar Nebula; the Kaidun Meteorite: Evidence for Pre- and Postaccretionary Aqueous Alteration; a Transmission Electron Microscope Study of the Matrix Mineralogy of the Leoville CV3 (Reduced-Group) Carbonaceous Chondrite: Nebular and Parent-Body Features; rubidium-Strontium Isotopic Systematic of Chondrules from the Antarctic CV Chondrites Yamato 86751 and Yamato 86009: Additional Evidence for Late Parent-Body Modification; oxygen-Fugacity Indicators in Carbonaceous Chondrites: Parent-Body Alteration or High-Temperature Nebular Oxidation; thermodynamic Modeling of Aqueous Alteration in CV Chondrites; asteroidal Modification of C and O Chondrites: Myths and Models; oxygen Fugacity in the Solar Nebular; and the History of Metal and Sulfides in Chondrites.

  9. Evidence for Extended Aqueous Alteration in CR Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Trigo-Rodriquez, J. M.; Moyano-Cambero, C. E.; Mestres, N.; Fraxedas, J.; Zolensky, M.; Nakamura, T.; Martins, Z.

    2013-01-01

    We are currently studying the chemical interrelationships between the main rockforming components of carbonaceous chondrites (hereafter CC), e.g. silicate chondrules, refractory inclusions and metal grains, and the surrounding meteorite matrices. It is thought that the fine-grained materials that form CC matrices are representing samples of relatively unprocessed protoplanetary disk materials [1-3]. In fact, modern non-destructive analytical techniques have shown that CC matrices host a large diversity of stellar grains from many distinguishable stellar sources [4]. Aqueous alteration has played a role in homogeneizing the isotopic content that allows the identification of presolar grains [5]. On the other hand, detailed analytical techniques have found that the aqueously-altered CR, CM and CI chondrite groups contain matrices in which the organic matter has experienced significant processing concomitant to the formation of clays and other minerals. In this sense, clays have been found to be directly associated with complex organics [6, 7]. CR chondrites are particularly relevant in this context as this chondrite group contains abundant metal grains in the interstitial matrix, and inside glassy silicate chondrules. It is important because CR are known for exhibiting a large complexity of organic compounds [8-10], and only metallic Fe is considered essential in Fischer-Tropsch catalysis of organics [11-13]. Therefore, CR chondrites can be considered primitive materials capable to provide clues on the role played by aqueous alteration in the chemical evolution of their parent asteroids.

  10. The Th and U abundances in chondritic meteorites

    NASA Technical Reports Server (NTRS)

    Chen, J. H.; Wasserburg, G. J.; Papanastassiou, D. A.

    1993-01-01

    We present new analyses of Th-232/U-238 in CI and CM meteorites. The relative abundance of these nuclides is important in estimates of the age of r-process elements. The cosmochronology based upon the Th-232/U-238 ratio (kappa) depends on the precise determinations of these two different elements in meteorites and on the production ratios. Both parameters are subject to substantial errors. Recent recalculations of this chronology have used selected values from compilations but do not adequately address the errors in terms of a reliable data base. Morgan and Lovering provided extensive neutron activation analyses for ordinary chondrites which yield an average kappa of 3.6 +/- 0.4. Their work on carbonaceous chondrites showed a wide range in kappa from 2 to 6. More recent investigations by isotopic dilution have established the following: (1) highly variable kappa from 2.7 to 11 in Allende Ca-Al-rich inclusions and a value of 3.6 in the Orgueil CI1 chondrite; (2) a range from 2.71 to 6.63 for 7 L-type chondrites and a range from 2.7 to 4.4 for 6 L, H, and LL chondrites. A further investigation of this subject matter is presented.

  11. A review of observations of organic matter in fogs and clouds: Origin, processing and fate

    NASA Astrophysics Data System (ADS)

    Herckes, Pierre; Valsaraj, Kalliat T.; Collett, Jeffrey L.

    2013-10-01

    While fog and cloud composition has been studied for decades, most of the research was limited to inorganic species and fog acidity. Recently the focus has shifted towards organic matter in the atmospheric aqueous phase of fogs and clouds: its origin, reactivity and fate. An impressive number of fog and cloud chemistry observational studies have been performed over the last decade throughout the world. In the present work we will review the state of knowledge of atmospheric organic matter processing by fogs, with a focus on field observations. We start by reviewing observational studies in general and then discuss our knowledge on the occurrence of organic matter in fogs, its solubility, characterization and molecular speciation. Organic carbon concentrations can vary widely from approximately 1 mg C/L in remote marine environments to more than 100 mg C/L in polluted radiation fogs, accounting for a substantial part of fogwater solutes. The carbonaceous material can enter the droplets from the gas and particle phase and the scavenging behavior of fogs will be detailed. Observational studies showed evidence of aqueous phase transformation of organic material, in particular secondary organic aerosol (SOA) generation, in fog. Recent observations of biological material in fog suggest also an impact of biological processing within the droplets on fog organic matter. The review will end with a discussion of the impact of fog on the deposition fluxes of organic material and hence its atmospheric lifetime.

  12. Effect of nitrite on the formation of halonitromethanes during chlorination of organic matter from different origin

    NASA Astrophysics Data System (ADS)

    Hong, Huachang; Qian, Lingya; Xiao, Zhuoqun; Zhang, Jianqing; Chen, Jianrong; Lin, Hongjun; Yu, Haiying; Shen, Liguo; Liang, Yan

    2015-12-01

    Occurrence of halonitromethanes (HNMs) in drinking water has been a public concern due to the potential risks to human health. Though quite a lot of work has been carried out to understand the formation of HNMs, the relationship between HNMs formation and the nitrite remains unclear. In this study, the effects of nitrite on the formation of HNMs during chlorination of organic matter from different origin were assessed. Organic matter (OM) derived from phoenix tree (fallen leaves: FLOM; green leaves: GLOM) and Microcystis aeruginosa (intracellular organic matter: IOM) were used to mimic the allochthonous and autochthonous organic matter in surface water, respectively. Results showed that HNMs yields were significantly enhanced with the addition of nitrite, and the highest enhancement was observed for FLOM, successively followed by GLOM and IOM, suggesting that the contribution of nitrite to HNMs formation was positively related with SUVA (an indicator for aromaticity) of OM. Therefore, the nitrite contamination should be strictly controlled for the source water dominated by allochthonous OM, which may significantly reduce the formation of HNMs during chlorination. Moreover, given a certain nitrite level, the higher pH resulted in higher stimulation of HNM formation, yet the chlorine dose (always added in excess resulting in residual reactive chlorine), reaction time and temperature did not show obvious influence.

  13. Experimental Impacts into Chondritic Targets. Part 1; Disruption of an L6 Chondrite by Multiple Impacts

    NASA Technical Reports Server (NTRS)

    Cintala, Mark J.; Horz, Friedrich

    2007-01-01

    A fragment of an L6 chondrite (ALH 85017,13) with an initial mass (M(sub 0)) of 464.1 g was the target in a series of experimental impacts in which the largest remaining fragment (M(sub R)) after each shot was impacted by a 3.18-mm ceramic sphere at a nominal speed of 2 km/s. This continued until the mass of the largest remaining piece was less than half the mass of the target presented to that shot (M(sub S)). Two chunks of Bushveldt gabbro with similar initial masses were also impacted under the same conditions until M(sub R) was less than half M(sub 0). The two gabbro targets required a total of 1.51x10(exp 7) and 1.75x10(exp 7) erg/g to attain 0.27 and 0.33 M(sub R)/M(sub 0), respectively; the chondrite, however, was considerably tougher, reaching 0.40 and 0.21 M(sub R)/M(sub 0) only after receiving 2.37x10(exp 7) and 3.10x10(exp 7) erg g-1, respectively. The combined ejecta and spallation products from the gabbro impacts were coarser than those from the chondrite and in sufficient quantities that the new surface areas exceeded those from the meteorite until the fifth shot in the chondrite series, which was the number of impacts required to disrupt each gabbro target (i.e., MR/M0 = 0.5). Unlike the behavior shown in previous regolith-evolution series, neither gabbro target produced an enhancement in the size fraction reflecting the mean size of the crystals composing the rock (about 3 mm), an effect possibly related to the width of the shock pulse. The original chondrite was so fine-grained and fractured, and the variance in its grain-size distribution so large, that effects related to grain-size were relegated to the <63- m fraction. Impacts into ALH 85017 produced abundant, fine-grained debris, but otherwise the slopes of its size distributions were comparable to those from other experiments involving natural and fabricated terrestrial targets. The characteristic slopes of the chondrite's size distributions, however, were notably more constant over the entire

  14. Matrices of carbonaceous chondrite meteorites

    NASA Technical Reports Server (NTRS)

    Buseck, Peter R.; Hua, Xin

    1993-01-01

    The morphology, classification, and chemistry of the matrices of carbonaceous chondrite (CC) meteorites is reviewed based on recent research results. The various kinds of CCs are examined in terms of their matrix mineralogy. Alteration processes in CCs are discussed.

  15. Origin of kinks in the energy dispersion of strongly correlated matter

    NASA Astrophysics Data System (ADS)

    Matsuyama, Kazue; Perepelitsky, Edward; Shastry, B. Sriram

    2017-04-01

    We investigate the origin of ubiquitous low-energy kinks found in angle-resolved photoemission experiments in a variety of correlated matter. Such kinks are unexpected from weakly interacting electrons and hence identifying their origin should lead to fundamental insights in strongly correlated matter. We devise a protocol for extracting the kink momentum and energy from the experimental data which relies solely on the two asymptotic tangents of each dispersion curve, away from the feature itself. It is thereby insensitive to the different shapes of the kinks as seen in experiments. The body of available data are then analyzed using this method. We proceed to discuss two alternate theoretical explanations of the origin of the kinks. Some theoretical proposals invoke local bosonic excitations (Einstein phonons or other modes with spin or charge character), located exactly at the energy of observed kinks, leading to a momentum-independent self-energy of the electrons. A recent alternate is the theory of extremely correlated Fermi liquids (ECFL). This theory predicts kinks in the dispersion arising from a momentum-dependent self-energy of correlated electrons. We present the essential results from both classes of theories, and identify experimental features that can help distinguish between the two mechanisms. The ECFL theory is found to be consistent with currently available data on kinks in the nodal direction of cuprate superconductors, but conclusive tests require higher-resolution energy distribution curve data.

  16. Tracing origins of sewage and organic matter using dissolved sterols in Masan and Haengam Bay, Korea

    NASA Astrophysics Data System (ADS)

    Lee, Hyo Jin; Hong, Sang Hee; Kim, Moonkoo; Ha, Sung Yong; An, Soon Mo; Shim, Won Joon

    2011-06-01

    Masan and Haengam Bays in Korea are highly polluted and semi-enclosed. Domestic and industrial effluents are directly or indirectly discharged into the bays through sewage treatment plants (STP) and creeks. In this study, 15 dissolved sterol compounds were determined in order to understand their sources and relative contribution. Freshwater samples were taken from 13 creeks and at two STP sites on a monthly basis. Total dissolved sterol concentrations ranged from 993 to 4158 ng/L. The concentrations of sterols in winter were higher than in summer. Among the sterols analyzed, cholesterol, β-sitosterol, coprostanol and cholestanone were major compounds in creek water. Seawater samples were concurrently collected at 21 stations in Masan Bay. Total sterol concentrations ranged 118-6,956 ng/L. Inner bay showed high concentrations of sterols in summer, while outer bay showed high sterol concentrations in winter. Among the sterols, cholesterol, β-sitosterol and brassicasterol were major compounds in seawater. In order to examine the contribution of urban sewage, the concentration of coprostanol and fecal sterol ratios were calculated. Most of the creek water, inner bay and near STP outlet samples were affected by sewage. Terrestrial organic matters accounted for a high proportion of dissolved organic matter origin. Fecal origins were relatively high in the inner bay areas and in the STP outlet, while sterols of marine origin were high in the outer bay areas.

  17. Chondrites and the Protoplanetary Disk

    NASA Astrophysics Data System (ADS)

    Scott, Edward R. D.

    2007-05-01

    Major advances in deciphering the record of nebula processes in chondrites can be attributed to analytical improvements that allow coordinated isotopic and mineralogical studies of components in chondrites and to a wealth of new meteorites from hot and cold deserts. These studies have identified a few rare pristine chondrites that largely escaped heating and alteration in asteroids, which have matrices composed of submicrometer-sized grains of enstatite and forsterite and amorphous silicates, as found in comets. Isotopic analyses of components in pristine chondrites using short-lived nuclide chronometers, Pb-Pb dating, and oxygen isotopes aided by laboratory and theoretical studies of chondrites and differentiated meteorites have provided key constraints on the processes that shaped the early solar system. These processes were once thought to have followed one another sequentially over a period of several million years: chondrule formation; planetesimal accretion; alteration, metamorphism, and melting in planetesimals; and finally, high-velocity collisions between asteroids. Radiometric dating shows, however, that these processes overlapped so that chondrules were still forming in the nebula several million years after early-formed planetesimals had melted and collided. Chondrites are extraordinary mixtures of presolar and solar nebula materials and asteroidal debris.

  18. Sayama CM2 Chondrite: Fresh but Heavily Altered

    NASA Technical Reports Server (NTRS)

    Takaoka, N.; Nakamura, T.; Noguchi, T.; Tonui, E.; Gounelle, M.; Zolensky, M. E.; Ebisawa, N.; Osawa, T.; Okazaki, R.; Nagao, K.; Yoneda, S.

    2001-01-01

    Noble gas composition and mineralogy of Sayama meteorite, that fell in Japan and recently identified as a CM2 chondrite, revealed many unique features, indicating that it experienced extensive aqueous alteration under highly oxidized condition compared with typical CMs. Additional information is contained in the original extended abstract.

  19. Mineralogy of Tagish Lake, a Unique Type 2 Carbonaceous Chondrite

    NASA Technical Reports Server (NTRS)

    Gounelle, M.; Zolensky, M. E.; Tonui, E.; Mikouchi, T.

    2001-01-01

    We have identified in Tagish Lake an abondant carbonate-poor lithology and a less common carbonate-rich lithology. Tagish Lake shows similarities and differences with CMs and CI1s. It is a unique carbonaceous chondrite recording specific aqueous alteration conditions. Additional information is contained in the original extended abstract.

  20. Primitive Fine-Grained Matrix in the Unequilbrated Enstatite Chondrites

    NASA Technical Reports Server (NTRS)

    Weisberg, M. K.; Zolensky, M. E.; Kimura, M.; Ebel, D. S.

    2014-01-01

    Enstatite chondrites (EC) have important implications for constraining conditions in the early solar system and for understanding the evolution of the Earth and other inner planets. They are among the most reduced solar system materials as reflected in their mineral compositions and assemblage. They are the only chondrites with oxygen as well as Cr, Ti, Ni and Zn stable isotope compositions similar to the earth and moon and most are completely dry, lacking any evidence of hydrous alteration; the only exception are EC clasts in the Kaidun breccia which have hydrous minerals. Thus, ECs likely formed within the snow line and are good candidates to be building blocks of the inner planets. Our goals are to provide a more detailed characterization the fine-grained matrix in E3 chondrites, understand its origin and relationship to chondrules, decipher the relationship between EH and EL chondrites and compare E3 matrix to matrices in C and O chondrites as well as other fine-grained solar system materials. Is E3 matrix the dust remaining from chondrule formation or a product of parent body processing or both?

  1. Mapping the Origins of Chromophoric Dissolved Organic Matter in the North Atlantic Subtropical Gyre

    NASA Astrophysics Data System (ADS)

    McDonald, N.; Logendran, V.; Evans, D. G.; Peters, A.; Nelson, N. B.

    2010-12-01

    The chromophoric or "light-absorbing" fraction of dissolved organic matter plays a significant role in the regulation of the underwater light field. In the North Atlantic subtropical gyre, it's origins vary, and include contributions from both terrestrial and marine sources. Furthermore, within the fraction of marine-origin CDOM, there are distinctions between that of local origin and that coming from other regions via transport through water masses or through atmospheric deposition. As the optical and chemical properties of CDOM depend largely on its source, an analysis of its origins could lead to a better understanding of processes in the North Atlantic subtropical gyre. For this analysis, we have used absorption data from CDOM measurements collected repeatedly for a number of years at the BATS site in the Sargasso Sea. Samples have been collected at the same series of depths ranging from surface waters to 4200 meters. The samples were analyzed using a dual beam spectrophotometer to obtain absorption spectra. The slope parameter, S, provides more in depth information about the source of CDOM than does the absorption spectra alone, and thus we have used it as well as the slope ratio, Sr, for differentiating between different types of CDOM. Slope ratios were obtained by selecting portions of the spectral slope at wavelength ranges, which have been found to be indicative of CDOM originating from a particular source. For example, it can be used to distinguish marine CDOM formed locally in the Sargasso Sea from that which has been formed further north in the Atlantic and then subducted and transported to the Sargasso. There are various other methods for ascertaining the sources of CDOM, and the most comprehensive model for CDOM in the North Atlantic is likely obtained using a combination of all of them. Excitation-emission matrix spectra (EEMS) have been performed on samples from the same site in the Sargasso Sea to corroborate findings from the S and Sr analyses

  2. Nanometer-Scale Measurements of Ferrous-Ferric Ratios in Chondritic Cronstedtite

    NASA Technical Reports Server (NTRS)

    Zega, T. J.; Garvie, L. A. J.; Buseck, P. R.

    2002-01-01

    We have determined the ferrous-ferric ratio in chondritic cronstedtite at the nanometer scale using electron energy-loss spectroscopy and transmission electron microscopy. Additional information is contained in the original extended abstract.

  3. Cr and O Isotope Systematics in CV/CK Chondrite Chondrules

    NASA Astrophysics Data System (ADS)

    Defouilloy, C.; Sanborn, M. E.; Yamakawa, A.; Kita, N. T.; Ebel, D. S.; Yin, Q.-Z.

    2017-02-01

    Combined in-situ high-precision measurements of Cr and O isotopic ratios reveal heterogeneities of compositions and the diversity of reservoirs of origin of silicate grains in CV/CK chondrite chondrules.

  4. Titanium and Oxygen Isotope Compositions of Individual Chondrules from Ordinary Chondrites

    NASA Astrophysics Data System (ADS)

    Bauer, K. K.; Schönbächler, M.; Fehr, M. A.; Vennemann, T.; Chaumard, N.; Zanda, B.

    2016-08-01

    We measured Ti and triple-O isotope compositions of individual chondrules (characterized by CT scanning) from ordinary chondrites. We will discuss correlations between Ti and ∆17O and their implication for the origin of nucleosynthetic anomalies.

  5. Zero point energy as origin of dark energy and dark matter

    NASA Astrophysics Data System (ADS)

    Lehnert, Bo

    2012-04-01

    An attempt is made to explain dark energy and dark matter of the expanding universe in terms of the zero point vacuum energy. This analysis is mainly limited to later stages of an observable nearly flat universe. It is based on a revised formulation of the spectral distribution of the zero point energy, for an ensemble in a defined statistical equilibrium having finite total energy density. The steady and dynamic states are studied for a spherical cloud of zero point energy photons. The "antigravitational" force due to its pressure gradient then represents dark energy, and its gravitational force due to the energy density represents dark matter. Four fundamental results come out of the theory. First, the lack of emitted radiation becomes reconcilable with the concepts of dark energy and dark matter. Second, the crucial coincidence problem of equal orders of magnitude of mass density and vacuum energy density cannot be explained by the cosmological constant, but is resolved by the present variable concepts which originate from the same photon gas balance. Third, the present approach becomes reconcilable with cosmical dimensions and with the radius of the observable universe. Fourth, the deduced acceleration of the expansion agrees with the observed one.

  6. MULTIPLE ORIGINS OF NITROGEN ISOTOPIC ANOMALIES IN METEORITES AND COMETS

    SciTech Connect

    Aleon, Jerome

    2010-10-20

    Isotopic fractionation and mixing calculations compared with coupled hydrogen and nitrogen isotopic composition of organic molecules from primitive chondrites, interplanetary dust particles (IDPs), and comets C/1995 O1 (Hale-Bopp) and 81P/Wild2 reveal that meteoritic and cometary organic matter contains three different isotopic components of different origins. (1) A major component of carbonaceous chondrites, IDPs, and comets Hale-Bopp and Wild2 shows correlated H and N isotopic compositions attributable to isotope exchange between an organic matter of solar composition and a reservoir formed by ion-molecule reactions at T < 25 K under conditions where competing reactions are strongly inhibited, possibly in the final evolutionary stages of the presolar cloud core, or more likely in the coldest outer regions of the solar protoplanetary disk. (2) In carbonaceous chondrites, IDPs, and comet Wild2, this component is mixed with a {sup 15}N-rich component having identical {sup 15}N and D enrichments relative to the protosolar gas. Temperatures > 100 K deduced from the low D/H ratio and an anti-correlation between the abundance of this component and meteoritic age indicate a late origin in the solar protoplanetary disk. N{sub 2} self-shielding and the non-thermal nucleosynthesis of {sup 15}N upon irradiation are possible but unlikely sources of this component, and a chemical origin is preferred. (3) An interstellar component with highly fractionated hydrogen isotopes and unfractionated nitrogen isotopes is present in ordinary chondrites. A dominantly solar origin of D and {sup 15}N excesses in primitive solar system bodies shows that isotopic anomalies do not necessarily fingerprint an interstellar origin and implies that only a very small fraction of volatile interstellar matter survived the events of solar system formation.

  7. Light in condensed matter in the upper atmosphere as the origin of homochirality: circularly polarized light from Rydberg matter.

    PubMed

    Holmlid, Leif

    2009-01-01

    Clouds of the condensed excited Rydberg matter (RM) exist in the atmospheres of comets and planetary bodies (most easily observed at Mercury and the Moon), where they surround the entire bodies. Vast such clouds are recently proposed to exist in the upper atmosphere of Earth (giving rise to the enormous features called noctilucent clouds, polar mesospheric clouds, and polar mesospheric summer radar echoes). It has been shown in experiments with RM that linearly polarized visible light scattered from an RM layer is transformed to circularly polarized light with a probability of approximately 50%. The circular Rydberg electrons in the magnetic field in the RM may be chiral scatterers. The magnetic and anisotropic RM medium acts as a circular polarizer probably by delaying one of the perpendicular components of the light wave. The delay process involved is called Rabi-flopping and gives delays of the order of femtoseconds. This strong effect thus gives intense circularly polarized visible and UV light within RM clouds. Amino acids and other chiral molecules will experience a strong interaction with this light field in the upper atmospheres of planets. The interaction will vary with the stereogenic conformation of the molecules and in all probability promote the survival of one enantiomer. Here, this strong effect is proposed to be the origin of homochirality. The formation of amino acids in the RM clouds is probably facilitated by the catalytic effect of RM.

  8. The Origin of Inertia and Matter as a Superradiant Phase Transition of Quantum Vacuum

    NASA Astrophysics Data System (ADS)

    Maxmilian Caligiuri, Luigi

    Mass is one of the most important concepts in physics and its real understanding represents the key for the formulation of any consistent physical theory. During the past years, a very interesting model of inertial and gravitational mass as the result of the reaction interaction between the charged particles (electrons and quarks) contained in a given body and a suitable "fraction" of QED Zero Point Fields confined within an ideal resonant cavity, associated to the same body, has been proposed by Haish, Rueda and Puthoff. More recently, the author showed that this interpretation is consistent with a picture of mass (both inertial and gravitational) as the seat of ZPF standing waves whose presence reduces quantum vacuum energy density inside the resonant cavity ideally associated to the body volume. Nevertheless so far, the ultimate physical origin of such resonant cavity as well as the mechanism able to "select" the fraction of ZPF electromagnetic modes interacting within it, remained unrevealed. In this paper, basing on the framework of QED coherence in condensed matter, we'll show mass can be viewed as the result of a spontaneous superradiant phase transition of quantum vacuum giving rise to a more stable, energetically favored, oscopic quantum state characterized by an ensemble of coherence domains, "trapping" the coherent ZPF fluctuations inside a given volume just acting as a resonant cavity. Our model is then able to explain the "natural" emergence of the ideal resonant cavity speculated by Haish, Rueda and Puthoff and its defining parameters as well as the physical mechanism selecting the fraction of ZPF interacting with the body particles. Finally, a generalization of the model to explain the origin of mass of elementary particles is proposed also suggesting a new understanding of Compton's frequency and De Broglie's wavelength. Our results indicates both inertia and matter could truly originate from coherent interaction between quantum matter-wave and

  9. Origin and sources of dissolved organic matter in snow on the East Antarctic ice sheet.

    PubMed

    Antony, Runa; Grannas, Amanda M; Willoughby, Amanda S; Sleighter, Rachel L; Thamban, Meloth; Hatcher, Patrick G

    2014-06-03

    Polar ice sheets hold a significant pool of the world's carbon reserve and are an integral component of the global carbon cycle. Yet, organic carbon composition and cycling in these systems is least understood. Here, we use ultrahigh resolution mass spectrometry to elucidate, at an unprecedented level, molecular details of dissolved organic matter (DOM) in Antarctic snow. Tens of thousands of distinct molecular species are identified, providing clues to the nature and sources of organic carbon in Antarctica. We show that many of the identified supraglacial organic matter formulas are consistent with material from microbial sources, and terrestrial inputs of vascular plant-derived materials are likely more important sources of organic carbon to Antarctica than previously thought. Black carbon-like material apparently originating from biomass burning in South America is also present, while a smaller fraction originated from soil humics and appears to be photochemically or microbially modified. In addition to remote continental sources, we document signals of oceanic emissions of primary aerosols and secondary organic aerosol precursors. The new insights on the diversity of organic species in Antarctic snowpack reinforce the importance of studying organic carbon associated with the Earth's polar regions in the face of changing climate.

  10. Using fluorescent dissolved organic matter to trace and distinguish the origin of Arctic surface waters

    NASA Astrophysics Data System (ADS)

    Gonçalves-Araujo, Rafael; Granskog, Mats A.; Bracher, Astrid; Azetsu-Scott, Kumiko; Dodd, Paul A.; Stedmon, Colin A.

    2016-09-01

    Climate change affects the Arctic with regards to permafrost thaw, sea-ice melt, alterations to the freshwater budget and increased export of terrestrial material to the Arctic Ocean. The Fram and Davis Straits represent the major gateways connecting the Arctic and Atlantic. Oceanographic surveys were performed in the Fram and Davis Straits, and on the east Greenland Shelf (EGS), in late summer 2012/2013. Meteoric (fmw), sea-ice melt, Atlantic and Pacific water fractions were determined and the fluorescence properties of dissolved organic matter (FDOM) were characterized. In Fram Strait and EGS, a robust correlation between visible wavelength fluorescence and fmw was apparent, suggesting it as a reliable tracer of polar waters. However, a pattern was observed which linked the organic matter characteristics to the origin of polar waters. At depth in Davis Strait, visible wavelength FDOM was correlated to apparent oxygen utilization (AOU) and traced deep-water DOM turnover. In surface waters FDOM characteristics could distinguish between surface waters from eastern (Atlantic + modified polar waters) and western (Canada-basin polar waters) Arctic sectors. The findings highlight the potential of designing in situ multi-channel DOM fluorometers to trace the freshwater origins and decipher water mass mixing dynamics in the region without laborious samples analyses.

  11. Using fluorescent dissolved organic matter to trace and distinguish the origin of Arctic surface waters

    PubMed Central

    Gonçalves-Araujo, Rafael; Granskog, Mats A.; Bracher, Astrid; Azetsu-Scott, Kumiko; Dodd, Paul A.; Stedmon, Colin A.

    2016-01-01

    Climate change affects the Arctic with regards to permafrost thaw, sea-ice melt, alterations to the freshwater budget and increased export of terrestrial material to the Arctic Ocean. The Fram and Davis Straits represent the major gateways connecting the Arctic and Atlantic. Oceanographic surveys were performed in the Fram and Davis Straits, and on the east Greenland Shelf (EGS), in late summer 2012/2013. Meteoric (fmw), sea-ice melt, Atlantic and Pacific water fractions were determined and the fluorescence properties of dissolved organic matter (FDOM) were characterized. In Fram Strait and EGS, a robust correlation between visible wavelength fluorescence and fmw was apparent, suggesting it as a reliable tracer of polar waters. However, a pattern was observed which linked the organic matter characteristics to the origin of polar waters. At depth in Davis Strait, visible wavelength FDOM was correlated to apparent oxygen utilization (AOU) and traced deep-water DOM turnover. In surface waters FDOM characteristics could distinguish between surface waters from eastern (Atlantic + modified polar waters) and western (Canada-basin polar waters) Arctic sectors. The findings highlight the potential of designing in situ multi-channel DOM fluorometers to trace the freshwater origins and decipher water mass mixing dynamics in the region without laborious samples analyses. PMID:27667721

  12. Actinide abundances in ordinary chondrites

    USGS Publications Warehouse

    Hagee, B.; Bernatowicz, T.J.; Podosek, F.A.; Johnson, M.L.; Burnett, D.S.; Tatsumoto, M.

    1990-01-01

    Measurements of 244Pu fission Xe, U, Th, and light REE (LREE) abundances, along with modal petrographic determinations of phosphate abundances, were carried out on equilibrated ordinary chondrites in order to define better the solar system Pu abundance and to determine the degree of variation of actinide and LREE abundances. Our data permit comparison of the directly measured Pu/ U ratio with that determined indirectly as (Pu/Nd) ?? (Nd/U) assuming that Pu behaves chemically as a LREE. Except for Guaren??a, and perhaps H chondrites in general, Pu concentrations are similar to that determined previously for St. Se??verin, although less precise because of higher trapped Xe contents. Trapped 130Xe 136Xe ratios appear to vary from meteorite to meteorite, but, relative to AVCC, all are similar in the sense of having less of the interstellar heavy Xe found in carbonaceous chondrite acid residues. The Pu/U and Pu/Nd ratios are consistent with previous data for St. Se??verin, but both tend to be slightly higher than those inferred from previous data on Angra dos Reis. Although significant variations exist, the distribution of our Th/U ratios, along with other precise isotope dilution data for ordinary chondrites, is rather symmetric about the CI chondrite value; however, actinide/(LREE) ratios are systematically lower than the CI value. Variations in actinide or LREE absolute and relative abundances are interpreted as reflecting differences in the proportions and/or compositions of more primitive components (chondrules and CAI materials?) incorporated into different regions of the ordinary chondrite parent bodies. The observed variations of Th/U, Nd/U, or Ce/U suggest that measurements of Pu/U on any single equilibrated ordinary chondrite specimen, such as St. Se??verin, should statistically be within ??20-30% of the average solar system value, although it is also clear that anomalous samples exist. ?? 1990.

  13. Experimental impacts into chondritic targets, part I: Disruption of an L6 chondrite by multiple impacts

    NASA Astrophysics Data System (ADS)

    Cintala, Mark J.; Hörz, Friedrich

    2008-04-01

    A fragment of an L6 chondrite (Allan Hills [ALH] 85017,13) with an initial mass (M0) of 464.1 g was the target in a series of experimental impacts in which the largest remaining fragment (MR) after each shot was impacted by a 3.18 mm ceramic sphere at a nominal speed of 2 km s-1. This continued until the mass of the largest remaining piece was less than half the mass of the target presented to that shot (MS). Two chunks of Bushveldt gabbro with similar initial masses were also impacted under the same conditions until MR was less than half M0. The two gabbro targets required a total of 1.51 × 107 and 1.75 × 107 erg g-1 to attain 0.27 and 0.33 MR/M0, respectively; the chondrite, however, was considerably tougher, reaching 0.40 and 0.21 MR/M0 only after receiving 2.37 × 107 and 3.10 × 107 erg g-1, respectively. The combined ejecta and spallation products from the gabbro impacts were coarser than those from the chondrite and in sufficient quantities that the new surface areas exceeded those from the meteorite until the fifth shot in the chondrite series, which was the number of impacts required to disrupt each gabbro target (i.e., MR/M0 ≤ 0.5). Unlike the behavior shown in previous regolith-evolution series, neither gabbro target produced an enhancement in the size fraction reflecting the mean size of the crystals composing the rock (about 3 mm), an effect possibly related to the width of the shock pulse. The original chondrite was so fine-grained and fractured, and the variance in its grain-size distribution so large, that effects related to grain size were relegated to the <63 μm fraction. Impacts into ALH 85017 produced abundant, fine-grained debris, but otherwise the slopes of its size distributions were comparable to those from other experiments involving natural and fabricated terrestrial targets. The characteristic slopes of the chondrite’s size distributions, however, were notably more constant over the entire nine-impact series than those from any of

  14. Multiple impact events recorded in the NWA 7298 H chondrite breccia and the dynamical evolution of an ordinary chondrite asteroid

    NASA Astrophysics Data System (ADS)

    Friedrich, Jon M.; Weisberg, Michael K.; Rivers, Mark L.

    2014-05-01

    The major geologic process that has shaped the asteroids and led to development of their regoliths is impact. Petrofabrics in ordinary chondrites are undoubtedly the result of impact events on their asteroidal parent bodies and the foliation present in a chondrite serves as an enduring record of the magnitude of the most intense compacting event experienced by the material. An overwhelming majority of chondrites have an internally consistent petrofabric contained within the spatial dimensions of the entire rock, including across clasts or different petrographic domains. This indicates that the magnitude of the most recent impact to have affected the assembled chondrite was significant enough to impart a foliation across all lithologies. Information of any previous impacts is largely lost because of the consistent, realigned foliations. We present X-ray microtomography derived 3D petrofabric intensity and orientation data for three lithologies in the NWA 7298 breccia. The internally inconsistent petrofabrics among differing lithologies indicate that the magnitude of the final impact event was smaller than previous ones. This latter case preserves fabric information recorded during previous impacts and allows a more complete interpretation of the impact history of a local region of the asteroidal parent. We used our data to infer the sequence and intensity of distinct impact events affecting the NWA 7298 parent asteroid. We suggest a near-surface impact debris zone on the H chondrite parent asteroid as an origin for NWA 7298. These observations yield new opportunities for investigating and interpreting the dynamic collisional evolution of asteroids.

  15. Primordial noble gases in chondrites: the abundance pattern was established in the solar nebula.

    PubMed

    Alaerts, L; Lewis, R S; Anders, E

    1977-12-02

    Ordinary chondrites, like carbonaceous chondrites, contain primordial noble gases mainly in a minor phase comprising matter apparently condensed over a substantial range of temperatures.

  16. Primordial noble gases in chondrites - The abundance pattern was established in the solar nebula

    NASA Technical Reports Server (NTRS)

    Alaerts, L.; Lewis, R. S.; Anders, E.

    1977-01-01

    Ordinary chondrites, like carbonaceous chondrites, contain primordial noble gases mainly in a minor phase comprising not more than 0.05 percent of the meteorite, probably an iron-chromium sulfide. The neon-20/argon-36 ratios decrease with increasing argon-36 concentration, as expected if the gas pattern was established by condensation from the solar nebula, and was negligibly altered by metamorphism in the meteorite parent bodies. Meteoritic and planetary matter apparently condensed over a substantial range of temperatures.

  17. Tracing the Origins of Organic Matter in the Ice of Svalbard, Norway

    NASA Astrophysics Data System (ADS)

    Vidonish, J. E.; Bowden, R.; Benning, L. G.; Eigenbrode, J. L.; Fogel, M. L.

    2011-12-01

    Determining the origin of organic matter (OM) in Arctic ice is of key importance in understanding the nature and origin of life in both modern and ancient ice. In turn, knowledge of this OM is important for studying biosignatures of ice, necessary for the search for life on Mars. In a study of samples from Svalbard, Norway, both stable isotope analysis and the presence of a unique UV-absorbing pigment (scytonemin) serve as a means of tracing potential sources of organic matter to glacial ice. Possible sources for glacial OM include the following: 1) aeolian sources including black carbon or local soils, creating "dirty snow", 2) plant sources from surrounding areas including higher plants, lichens, and mosses, 3) microbial sources from on the ice itself , i.e., snow algae and cryoconites, and 4) microbial biofilms and endoliths from nearby habitats.. The UV-sunscreen pigment scytonemin is prevalent in many of the sources, particularly snow algae, cryoconites, lichens and microbial biofilms, as determined by spectrophotometry and ultra-performance LCMS analysis. These same methods also revealed the presence of scytonemin in various ice cores and surface runoff samples, suggesting that these plant and microbial sources are indeed tied to the introduction of OM to the ice of Svalbard. Supporting pigment signature tracing, stable isotope analysis of 13C and 15N shows a clear trend confirming the origin of OM from regional organic matter, as both ice cores and runoff have an isotopic signature comparable to Svalbard plants, snow algae, cryconites, and lichen. These two lines of evidence conclude in tandem that the OM found in Svalbard's glaciers have an origin in the surrounding ecosystem. This finding suggests that traces of life can both be transported and preserved in ice for extended periods of time. This has especial meaning in the pursuit of biosignatures on Mars, as well as the study of paleoclimate on Earth. Future studies can focus on further tracing of

  18. Origin of fine carbonaceous particulate matter in the Western Mediterranean Basin: fossil versus modern sources

    NASA Astrophysics Data System (ADS)

    Cruz Minguillón, María.; Perron, Nolwenn; Querol, Xavier; Szidat, Sönke; Fahrni, Simon; Wacker, Lukas; Reche, Cristina; Cusack, Michael; Baltensperger, Urs; Prévôt, André S. H.

    2010-05-01

    The present work was carried out in the frame of the international field campaign DAURE (Determination of the sources of atmospheric Aerosols in Urban and Rural Environments in the western Mediterranean). The objective of this campaign is to study the aerosol pollution episodes occurring at regional scale during winter and summer in the Western Mediterranean Basin. As part of this campaign, this work focuses on identifying the origin of fine carbonaceous aerosols. To this end, fine particulate matter (PM1) samples were collected during two different seasons (February-March and July 2009) at two sites: an urban site (Barcelona, NE Spain) and a rural European Supersite for Atmospheric Aerosol Research (Montseny, NE Spain). Subsequently, 14C analyses were carried out on these samples, both in the elemental carbon (EC) fraction and the organic carbon (OC) fraction, in order to distinguish between modern carbonaceous sources (biogenic emissions and biomass burning emissions) and fossil carbonaceous sources (mainly road traffic). Preliminary results from the winter period show that 40% of the OC at Barcelona has a fossil origin whereas at Montseny this percentage is 30%. These values can be considered as unexpected given the nature of the sites. Nevertheless, the absolute concentrations of fossil OC at Barcelona and Montseny differ by a factor of 2 (the first being higher), since the total OC at Montseny is lower than at Barcelona. Further evaluation of results and comparison with other measurements carried out during the campaign are required to better evaluate the origin of the fine carbonaceous matter in the Western Mediterranean Basin. Acknowledgements: Spanish Ministry of Education and Science, for a Postdoctoral Grant awarded to M.C. Minguillón in the frame of Programa Nacional de Movilidad de Recursos Humanos del Plan nacional de I-D+I 2008-2011. Spanish Ministry of Education and Science, for the Acción Complementaria DAURE CGL2007-30502-E/CLI.

  19. Extraterrestrial amino acids identified in metal-rich CH and CB carbonaceous chondrites from Antarctica

    NASA Astrophysics Data System (ADS)

    Burton, Aaron S.; Elsila, Jamie E.; Hein, Jason E.; Glavin, Daniel P.; Dworkin, Jason P.

    2013-03-01

    Carbonaceous chondrites contain numerous indigenous organic compounds and could have been an important source of prebiotic compounds required for the origin of life on Earth or elsewhere. Extraterrestrial amino acids have been reported in five of the eight groups of carbonaceous chondrites and are most abundant in CI, CM, and CR chondrites but are also present in the more thermally altered CV and CO chondrites. We report the abundance, distribution, and enantiomeric and isotopic compositions of simple primary amino acids in six metal-rich CH and CB carbonaceous chondrites that have not previously been investigated for amino acids: Allan Hills (ALH) 85085 (CH3), Pecora Escarpment (PCA) 91467 (CH3), Patuxent Range (PAT) 91546 (CH3), MacAlpine Hills (MAC) 02675 (CBb), Miller Range (MIL) 05082 (CB), and Miller Range (MIL) 07411 (CB). Amino acid abundances and carbon isotopic values were obtained by using both liquid chromatography time-of-flight mass spectrometry and fluorescence, and gas chromatography isotope ratio mass spectrometry. The δ13C/12C ratios of multiple amino acids fall outside of the terrestrial range and support their extraterrestrial origin. Extracts of CH chondrites were found to be particularly rich in amino acids (13-16 parts per million, ppm) while CB chondrite extracts had much lower abundances (0.2-2 ppm). The amino acid distributions of the CH and CB chondrites were distinct from the distributions observed in type 2 and 3 CM and CR chondrites and contained elevated levels of β-, γ-, and δ-amino acids compared to the corresponding α-amino acids, providing evidence that multiple amino acid formation mechanisms were important in CH and CB chondrites.

  20. Extraterrestrial Nucleobases in Carbonaceous Chondrites

    NASA Astrophysics Data System (ADS)

    Martins, Z.; Botta, O.; Fogel, M.; Sephton, M.; Glavin, D.; Watson, J.; Dworkin, J.; Schwartz, A.; Ehrenfreund, P.

    Nucleobases in Carbonaceous Chondrites Z. Martins (1), O. Botta (2), M. L. Fogel (3), M. A. Sephton (4), D. P. Glavin (2), J. S. Watson (5), J. P. Dworkin (2), A. W. Schwartz (6) and P. Ehrenfreund (1,6). (1) Astrobiology Laboratory, Leiden Institute of Chemistry, Leiden, The Netherlands, (2) NASA Goddard Space Flight Center, Goddard Center for Astrobiology, Greenbelt, MD, USA, (3) GL, Carnegie Institution of Washington, Washington DC, USA, (4) Impacts and Astromaterials Research Centre, Department of Earth Science and Engineering, South Kensington Campus, Imperial College, London, UK, (5) Planetary and Space Sciences Research Institute, The Open University, Walton Hall, Milton Keynes, UK, (6) Radboud University Nijmegen, Nijmegen, The Netherlands. E-mail: z.martins@chem.leidenuniv.nl/Phone:+31715274440 Nucleobases are crucial compounds in terrestrial biochemistry, because they are key components of DNA and RNA. Carbonaceous meteorites have been analyzed for nucleobases by different research groups [1-5]. However, significant quantitative and qualitative differences were observed, leading to the controversial about the origin of these nucleobases. In order to establish the origin of these compounds in carbonaceous chondrites and to assess the plausibility of their exogenous delivery to the early Earth, we have performed formic acid extraction of samples of the Murchison meteorite [6], followed by an extensive purification procedure, analysis and quantification by high-performance liquid chromatography with UV absorption detection and gas chromatography-mass spectrometry. Our results were qualitatively consistent with previous results [3, 4], but showed significant quantitative differences. Compound specific carbon isotope values were obtained, using gas chromatography-combustion- isotope ratio mass spectrometry. A soil sample collected in the proximity of the Murchison meteorite fall site was subjected to the same extraction, purification and analysis procedure

  1. A Raman spectroscopic study of organic matter in interplanetary dust particles and meteorites using multiple wavelength laser excitation

    NASA Astrophysics Data System (ADS)

    Starkey, N. A.; Franchi, I. A.; Alexander, C. M. O'd.

    2013-10-01

    Raman spectroscopy was used to investigate insoluble organic matter (IOM) from a range of chondritic meteorites, and a suite of interplanetary dust particles (IDPs). Three monochromatic excitation wavelengths (473 nm, 514 nm, 632 nm) were applied sequentially to assess variations in meteorite and IDP Raman peak parameters (carbon D and G bands) as a function of excitation wavelength (i.e., dispersion). Greatest dispersion occurs in CVs > OCs > CMs > CRs with type 3 chondrites compared at different excitation wavelengths displaying conformable relationships, in contrast to type 2 chondrites. These findings indicate homogeneity in the structural nature of type 3 chondrite IOM, while organic matter (OM) in type 2 chondrites appears to be inherently more heterogeneous. If type 2 and type 3 chondrite IOM shares a common source, then thermal metamorphism may have a homogenizing effect on the originally more heterogeneous OM. IDP Raman G bands fall on an extension of the trend displayed by chondrite IOM, with all IDPs having Raman parameters indicative of very disordered carbon, with almost no overlap with IOM. The dispersion effect displayed by IDPs is most similar to CMs for the G band, but intermediate between CMs and CRs for the D band. The existence of some overlapping Raman features in the IDPs and IOM indicates that their OM may share a common origin, but the IDPs preserve more pristine OM that may have been further disordered by ion irradiation. H, C, and N isotopic data for the IDPs reveal that the disordered carbon in IDPs corresponds with higher δ15N and lower δ13C.

  2. Reflectance spectra of primitive chondrites

    NASA Astrophysics Data System (ADS)

    Trigo-Rodríguez, J. M.; Moyano-Cambero, C. E.; Llorca, J.

    2013-05-01

    We are studying a wide sample of pristine carbonaceous chondrites from the NASA Antarctic collection in order to get clues on the physico-chemical processes occurred in the parent bodies of these meteorites. We are obtaining laboratory reflectance spectra of different groups of carbonaceous chondrites, but here we focus in CM and CI chondrites. We discuss the main spectral features that can be used to identify primitive carbonaceous asteroids by remote sensing techniques. Two different spectrometers were used covering the entire 0.3 to 30 μm electromagnetic window. Only a handful of Near Earth Objects (NEOs) exhibit bands or features clearly associated with aqueous alteration. Among them are the target asteroids of Osiris Rex and Marco Polo-R missions.

  3. Actinide abundances in ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Hagee, B.; Bernatowicz, T. J.; Podosek, F. A.; Johnson, M. L.; Burnett, D. S.

    1990-01-01

    Measurements of actinide and light REE (LREE) abundances and of phosphate abundances in equilibrated ordinary chondrites were obtained and were used to define the Pu abundance in the solar system and to determine the degree of variation of actinide and LREE abundances. The results were also used to compare directly the Pu/U ratio with the earlier obtained ratio determined indirectly, as (Pu/Nd)x(Nd/U), assuming that Pu behaves chemically as a LREE. The data, combined with high-accuracy isotope-dilution data from the literature, show that the degree of gram-scale variability of the Th, U, and LREE abundances for equilibrated ordinary chondrites is a factor of 2-3 for absolute abundances and up to 50 percent for relative abundances. The observed variations are interpreted as reflecting the differences in the compositions and/or proportions of solar nebula components accreted to ordinary chondrite parent bodies.

  4. Identification of Highly Fractionated (18)O-Rich Silicate Grains in the Queen Alexandra Range 99177 CR3 Chondrite

    NASA Technical Reports Server (NTRS)

    Nguyen, A. N.; Keller, L. P.; Messenger, S.; Rahman, Z.

    2015-01-01

    Carbonaceous chondrites contain a mixture of solar system condensates, presolar grains, and primitive organic matter. The CR3 chondrite QUE 99177 has undergone minimal al-teration [1], exemplified by abundant presolar silicates [2, 3] and anomalous organic matter [4]. Oxygen isotopic imaging studies of this meteorite have focused on finding submicrometer anomalous grains in fine-grained regions of thin sections. Here we present re-sults of an O isotopic survey of larger matrix grains.

  5. I-Xe Chronology of Enstatite Chondrites

    NASA Astrophysics Data System (ADS)

    Hopp, J.; Trieloff, M.; Ott, U.

    2013-09-01

    We report new I-Xe age data for EL and EH chondrites. The EL chondrites are ca.2.5-5 Ma younger, the EH chondrites are ca. 0.9 to 7.8 Ma younger than Shallowater meteorite. Ages appear influenced by both impact events and metamorphic cooling.

  6. Carlisle Lakes Chondrites: Relationship to Other Chondrite Groups

    NASA Astrophysics Data System (ADS)

    Rubin, A. E.; Kallemeyn, G. W.

    1993-07-01

    Although chondrites are all solarlike in their abundances of nonvolatile elements, there are appreciable differences among chondrite groups in texture and mineralogical, chemical, and O-isotopic composition. There are now 12 chondrite groups, each containing at least five members: CI, CR, CM, CO, CV, and CK carbonaceous chondrites; H, L, and LL ordinary chondrites; EH and EL enstatite chondrites; and Carlisle Lakes chondrites. Eight Carlisle Lakes chondrites have been identified: Carlisle Lakes, ALH 85151, Y 75302, Y 793575, Y 82002, Acfer 217, PCA 91002, and PCA 91241; the latter two may be paired. The primary petrographic characteristics of the group include abundant matrix (42 +/- 11 vol%) and chondrules averaging 400 micrometers in apparent diameter. Secondary petrographic characteristics include moderate metamorphic recrystallization and, in most members, extensive brecciation. As a family, carbonaceous chondrite groups (excepting CI in some cases) are characterized by (1) group/CI mean-refractory-lithophile/Si abundance ratios of 1.00-1.35, (2) a moderate to high degree of Fe oxidation, (3) high fine- grained-matrix/chondrule modal abundance ratios (0.5-7), (4) an appreciable abundance of refractory inclusions (~0.5-5 vol%), (5) whole-rock O-isotopic compositions significantly below the terrestrial fractionation (TF) line, (6) siderophile and chalcophile abundance patterns that decrease monotonically with increasing volatility (with low to moderate CI-normalized Se/Sb concentration ratios, 0.6-0.9), (7) relatively abundant opaque-mineral-rich porphyritic chondrules, and (8) where present, plagioclase with high molar An. Ordinary chondrites (OC) are characterized by (1) group/CI mean-refractory- lithophile/Si abundance ratios of 0.77-0.82, (2) a low to moderate degree of Fe oxidation, (3) low fine-grained-matrix/chondrule modal abundance ratios (~0.3, excluding metamorphosed OC), (4) a negligible abundance of refractory inclusions, (5) whole-rock O

  7. Isotopic characterization of kerogen-like material in the Murchison carbonaceous chondrite

    SciTech Connect

    Kerridge, J.F.; Chang, S.; Shipp, R.

    1987-09-01

    Isotopic data for C, H and N in acid-resistant residues from carbonaceous chondrites show substantial variability during stepwise pyrolysis and/or combustion. After subtraction of contributions due apparently to inorganic C grains, of probably circumstellar origin, considerable isotopic variability remains, attributable to the kerogen-like organic fraction. That variability may be interpreted in terms of three of four distinct components, based on C, H and N isotopes. The relative proportions of those components vary significantly from sample to sample. The different isotopic components are tentatively identified in terms of specific chemical/structural moieties within the kerogen-like material. This combination of chemical, structural and isotopic information suggests a complex history for meteoritic organic matter. At least three components within the organic population as a whole still carry a signature of apparently interstellar D-enrichment. Part, at least, of the interstellar carrier consisted of reactive entities, not solely polymers.

  8. Post-metamorphic brecciation in type 3 ordinary chondrites

    NASA Astrophysics Data System (ADS)

    Scott, E. R. D.; McCoy, T. J.; Keil, K.

    1993-03-01

    Type 3.1-3.9 ordinary chondrites can be divided into two kinds: those in which the compositions of chondrule silicates are entirely consistent with metamorphism of type 3.0 material, and those in which the computational heterogeneity appears to be too extreme for in situ metamorphism. We present petrologic data for three LL3 chondrites of the second kind--Ngawi, ALH A77278 (both type 3.6), and Hamlet (type 3.9)--and compare these data with results for the first kind of LL3-4 chondrites. Given that chondrules form in the nebula and that metamorphic equilibration occurs in asteroids, our new data imply that Ngawi, A77278, Hamlet, and many other type 3 ordinary chondrites are post-metamorphic breccias containing materials with diverse metamorphic histories; they are not metamorphic rocks or special kinds of 'primitive breccias.' We infer also that metamorphism to type 3.1-3.9 levels produces very friable material that is easily remixed into breccias and lithified by mild shock. Thus, petrologic types and subtypes of chondrites indicate the mean metamorphic history of the ingredients, not the thermal history of the rock. The metamorphic history of individual type 1 or 2 porphyritic chondrules in type 3 breccias is best derived from olivine and pyroxene analyses and the data of McCoy et al. for unbrecciated chondrites. The new chondrule classification schemes of Sears, DeHart et al., appears to provide less information about the original state and metamorphic history of individual porphyritic chondrules and should not replace existing classification schemes.

  9. Post-metamorphic brecciation in type 3 ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Scott, E. R. D.; Mccoy, T. J.; Keil, K.

    1993-01-01

    Type 3.1-3.9 ordinary chondrites can be divided into two kinds: those in which the compositions of chondrule silicates are entirely consistent with metamorphism of type 3.0 material, and those in which the computational heterogeneity appears to be too extreme for in situ metamorphism. We present petrologic data for three LL3 chondrites of the second kind--Ngawi, ALH A77278 (both type 3.6), and Hamlet (type 3.9)--and compare these data with results for the first kind of LL3-4 chondrites. Given that chondrules form in the nebula and that metamorphic equilibration occurs in asteroids, our new data imply that Ngawi, A77278, Hamlet, and many other type 3 ordinary chondrites are post-metamorphic breccias containing materials with diverse metamorphic histories; they are not metamorphic rocks or special kinds of 'primitive breccias.' We infer also that metamorphism to type 3.1-3.9 levels produces very friable material that is easily remixed into breccias and lithified by mild shock. Thus, petrologic types and subtypes of chondrites indicate the mean metamorphic history of the ingredients, not the thermal history of the rock. The metamorphic history of individual type 1 or 2 porphyritic chondrules in type 3 breccias is best derived from olivine and pyroxene analyses and the data of McCoy et al. for unbrecciated chondrites. The new chondrule classification schemes of Sears, DeHart et al., appears to provide less information about the original state and metamorphic history of individual porphyritic chondrules and should not replace existing classification schemes.

  10. The accretion history of dark matter haloes - I. The physical origin of the universal function

    NASA Astrophysics Data System (ADS)

    Correa, Camila A.; Wyithe, J. Stuart B.; Schaye, Joop; Duffy, Alan R.

    2015-06-01

    Understanding the universal accretion history of dark matter haloes is the first step towards determining the origin of their structure. We use the extended Press-Schechter formalism to derive the halo mass accretion history from the growth rate of initial density perturbations. We show that the halo mass history is well described by an exponential function of redshift in the high-redshift regime. However, in the low-redshift regime the mass history follows a power law because the growth of density perturbations is halted in the dark energy dominated era due to the accelerated expansion of the Universe. We provide an analytic model that follows the expression {M(z)=M0(1+z)^{af(M0)}e^{-f(M0)z}}, where M0 = M(z = 0), a depends on cosmology and f(M0) depends only on the linear matter power spectrum. The analytic model does not rely on calibration against numerical simulations and is suitable for any cosmology. We compare our model with the latest empirical models for the mass accretion history in the literature and find very good agreement. We provide numerical routines for the model online (available at https://bitbucket.org/astroduff/commah).

  11. An evaluation on different origins of natural organic matters using various anodes by electrocoagulation.

    PubMed

    Ulu, Feride; Barışçı, Sibel; Kobya, Mehmet; Sillanpää, Mika

    2015-04-01

    In this investigation, natural organic matters (NOM) of different origins (commercial, terrestrial and natural water) were treated by electrocoagulation (EC) process using aluminum, iron and hybrid electrodes. Electrode type effect on removal efficiency was observed for each NOM (commercial, terrestrial, and natural). The results were presented as dissolved organic carbon (DOC) (mg L(-1)) and UV/VIS absorbance (cm(-1)). The specific UV absorbance (SUVA) was determined before and after treatment of water. The lowest effluent concentration was obtained as 5.05 mg L(-1) with hybrid electrode for natural NOM source at its original pH 7.3. In addition, among the metal types, the best UV-abs-254 removal efficiency was obtained as 92.4% with 0.0312 cm(-1) by hybrid electrode at the end of the process. The color removal efficiency of water occurred successfully by Al and hybrid electrodes. Aquatic NOM source was the most resistant to EC treatment with DOC reduction of 71.1%, 59.8%, and 68.6% for Al, Fe and hybrid electrodes, respectively. Zeta potential and floc size of colloids were observed during the process for the determination of destabilization level of natural organic matters in EC process. Fast coagulation or flocculation and incipient instability were formed during electrolysis time for Al and Fe electrode, respectively. SUVA value was reduced to below 2 for three NOM sources studied. The EC process was shown to be a viable for different NOM sources with various metals. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Establishing a molecular relationship between chondritic and cometary organic solids

    PubMed Central

    Cody, George D.; Heying, Emily; Alexander, Conel M. O.; Nittler, Larry R.; Kilcoyne, A. L. David; Sandford, Scott A.

    2011-01-01

    Multidimensional solid-state NMR spectroscopy is used to refine the identification and abundance determination of functional groups in insoluble organic matter (IOM) isolated from a carbonaceous chondrite (Murchison, CM2). It is shown that IOM is composed primarily of highly substituted single ring aromatics, substituted furan/pyran moieties, highly branched oxygenated aliphatics, and carbonyl groups. A pathway for producing an IOM-like molecular structure through formaldehyde polymerization is proposed and tested experimentally. Solid-state 13C NMR analysis of aqueously altered formaldehyde polymer reveals considerable similarity with chondritic IOM. Carbon X-ray absorption near edge structure spectroscopy of formaldehyde polymer reveals the presence of similar functional groups across certain Comet 81P/Wild 2 organic solids, interplanetary dust particles, and primitive IOM. Variation in functional group concentration amongst these extraterrestrial materials is understood to be a result of various degrees of processing in the parent bodies, in space, during atmospheric entry, etc. These results support the hypothesis that chondritic IOM and cometary refractory organic solids are related chemically and likely were derived from formaldehyde polymer. The fine-scale morphology of formaldehyde polymer produced in the experiment reveals abundant nanospherules that are similar in size and shape to organic nanoglobules that are ubiquitous in primitive chondrites. PMID:21464292

  13. Searching for dark matter in X-rays: how to check the dark matter origin of a spectral feature

    NASA Astrophysics Data System (ADS)

    Boyarsky, Alexey; Ruchayskiy, Oleg; Iakubovskyi, Dmytro; Walker, Matthew G.; Riemer-Sørensen, Signe; Hansen, Steen H.

    2010-09-01

    A signal from decaying dark matter (DM) can be unambiguously distinguished from spectral features of astrophysical or instrumental origin by studying its spatial distribution. We demonstrate this approach by examining the recent claim of Loewenstein and Kusenko regarding the possible DM origin of the 2.5 keV line in Chandra observations of the Milky Way satellite known as Willman 1. Our conservative strategy is to adopt, among reasonable mass estimates derived here and in the literature, a relatively large dark mass for Willman 1 and relatively small dark masses for the comparison objects. In light of the large uncertainty in the actual DM content of Willman 1, this strategy provides minimum exclusion limits on the DM origin of the reported signal. We analyse archival observations by XMM-Newton of M31 and Fornax dwarf spheroidal galaxy (dSph) and Chandra observations of Sculptor dSph. By performing a conservative analysis of X-ray spectra, we show the absence of a DM decay line with parameters consistent with those of Loewenstein and Kusenko. For M31, the observations of the regions between 10 and 20 kpc from the centre, where the uncertainties in the DM distribution are minimal, make a strong exclusion at the level above 10σ. The Fornax dSph provides a ~3.3σ exclusion instead of a predicted 4σ detection, and the Sculptor dSph provides a 3σ exclusion instead of a predicted 2.5σ detection. The observations of the central region of M31 (1-3 kpc off-centre) are inconsistent with having a DM decay line at more than 20σ if one takes the most conservative among the best physically motivated models. The minimal estimate for the amount of DM in the central 40 kpc of M31 is provided by the model of Corbelli et al., assuming the stellar disc's mass to light ratio ~8 and almost constant DM density within a core of 28 kpc. Even in this case one gets an exclusion at 5.7σ from central region of M31, whereas modelling all processed data from M31 and Fornax produces more

  14. Long-lived magnetism on chondrite parent bodies

    NASA Astrophysics Data System (ADS)

    Shah, Jay; Bates, Helena C.; Muxworthy, Adrian R.; Hezel, Dominik C.; Russell, Sara S.; Genge, Matthew J.

    2017-10-01

    We present evidence for both early- and late-stage magnetic activity on the CV and L/LL parent bodies respectively from chondrules in Vigarano and Bjurböle. Using micro-CT scans to re-orientate chondrules to their in-situ positions, we present a new micron-scale protocol for the paleomagnetic conglomerate test. The paleomagnetic conglomerate test determines at 95% confidence, whether clasts within a conglomerate were magnetized before or after agglomeration, i.e., for a chondritic meteorite whether the chondrules carry a pre- or post-accretionary remanent magnetization. We found both meteorites passed the conglomerate test, i.e., the chondrules had randomly orientated magnetizations. Vigarano's heterogeneous magnetization is likely of shock origin, due to the 10 to 20 GPa impacts that brecciated its precursor material on the parent body and transported it to re-accrete as the Vigarano breccia. The magnetization was likely acquired during the break-up of the original body, indicating a CV parent body dynamo was active ∼9 Ma after Solar System formation. Bjurböle's magnetization is due to tetrataenite, which transformed from taenite as the parent body cooled to below 320 °C, when an ambient magnetic field imparted a remanence. We argue either the high intrinsic anisotropy of tetrataenite or brecciation on the parent body manifests as a randomly orientated distribution, and a L/LL parent body dynamo must have been active at least 80 to 140 Ma after peak metamorphism. Primitive chondrites did not originate from entirely primitive, never molten and/or differentiated parent bodies. Primitive chondrite parent bodies consisted of a differentiated interior sustaining a long-lived magnetic dynamo, encrusted by a layer of incrementally accreted primitive meteoritic material. The different ages of carbonaceous and ordinary chondrite parent bodies might indicate a general difference between carbonaceous and ordinary chondrite parent bodies, and/or formation location in the

  15. Shock Features in L6 Chondrite NWA 091: Search for Evidence of Very High Shock Pressure in Chondrites

    NASA Astrophysics Data System (ADS)

    Hu, J.; Sharp, T. G.; Weirich, J.

    2012-12-01

    Many L chondrites are thought to be highly shocked by the giant impact event on L chondrite parent body at 500Ma. Such a hypervelocity impact on the L chondrite parent body would generate very high pressures and abundant melting. However, the high-pressure phases in shock veins of L chondrites constrain the shock pressure up to a maximum of ~26GPa (Hu et al., 2012). NWA 091 is a L6 shock-melt breccia from the 500Ma event that is highly blackened (Welrich et al., 2012). It was originally classified as shock stage S4, based on the presence of plagioclase rather than maskelynite. We used Raman spectroscopy, field-emission SEM and analytical TEM to investigate the mineralogy and microstructure in NWA 091 to better estimate its shock pressure. Olivine and pyroxene in NWA 091 are laced with metal and sulfide veins and droplets, suggesting these fragments are highly shocked. The silicate melt veins and pockets include very fine-grained crystals with compositions of olivine, pyroxene and plagioclase. No high-pressure phases have been found in the veins. Plagioclase in this sample is poikilitic with inclusions of metal, sulfide and chromite. We will characterize the microstructure of plagioclase to determine if it is primary or has transformed from a high pressure phases after pressure release. Based on the microstructures observed so far, we interpret NWA091 as a very highly shocked (S6-7) chondrite that was annealed at high temperature after decompression. Thus the high-pressure polymorphs of rock-forming minerals are not preserved. Such post-shock annealing can explain why mineralogical evidence for pressure above 26GPa is lacking in L chondrites.

  16. Aliphatic amines in Antarctic CR2, CM2, and CM1/2 carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Aponte, José C.; McLain, Hannah L.; Dworkin, Jason P.; Elsila, Jamie E.

    2016-09-01

    Meteoritic water-soluble organic compounds provide a unique record of the processes that occurred during the formation of the solar system and the chemistry preceding the origins of life on Earth. We have investigated the molecular distribution, compound-specific δ13C isotopic ratios and enantiomeric compositions of aliphatic monoamines present in the hot acid-water extracts of the carbonaceous chondrites LAP 02342 (CR2), GRA 95229 (CR2), LON 94101 (CM2), LEW 90500 (CM2), and ALH 83100 (CM1/2). Analyses of the concentration of monoamines in these meteorites revealed: (a) the CR2 chondrites studied here contain higher concentrations of monoamines relative to the analyzed CM2 chondrites; (b) the concentration of monoamines decreases with increasing carbon number; and (c) isopropylamine is the most abundant monoamine in these CR2 chondrites, while methylamine is the most abundant amine species in these CM2 and CM1/2 chondrites. The δ13C values of monoamines in CR2 chondrite do not correlate with the number of carbon atoms; however, in CM2 and CM1/2 chondrites, the 13C enrichment decreases with increasing monoamine carbon number. The δ13C values of methylamine in CR2 chondrites ranged from -1 to +10‰, while in CM2 and CM1/2 chondrites the δ13C values of methylamine ranged from +41 to +59‰. We also observed racemic compositions of sec-butylamine, 3-methyl-2-butylamine, and sec-pentylamine in the studied carbonaceous chondrites. Additionally, we compared the abundance and δ13C isotopic composition of monoamines to those of their structurally related amino acids. We found that monoamines are less abundant than amino acids in CR2 chondrites, with the opposite being true in CM2 and CM1/2 chondrites. We used these collective data to evaluate different primordial synthetic pathways for monoamines in carbonaceous chondrites and to understand the potential common origins these molecules may share with meteoritic amino acids.

  17. Aliphatic Amines in Antarctic CR2, CM2, and CM1/2 Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Aponte, Jose C.; McLain, Hannah L.; Dworkin, Jason P.; Elsila, Jamie E.

    2016-01-01

    Meteoritic water-soluble organic compounds provide a unique record of the processes that occurred during the formation of the solar system and the chemistry preceding the origins of life on Earth. We have investigated the molecular distribution, compound-specific delta13C isotopic ratios and enantiomeric compositions of aliphatic monoamines present in the hot acid-water extracts of the carbonaceous chondrites LAP 02342 (CR2), GRA 95229 (CR2), LON 94101 (CM2), LEW 90500 (CM2), and ALH 83100 (CM1/2). Analyses of the concentration of monoamines in these meteorites revealed: (a) the CR2 chondrites studied here contain higher concentrations of monoamines relative to the analyzed CM2 chondrites; (b) the concentration of monoamines decreases with increasing carbon number; and (c) isopropylamine is the most abundant monoamine in these CR2 chondrites, while methylamine is the most abundant amine species in these CM2 and CM1/2 chondrites. The delta13C values of monoamines in CR2 chondrite do not correlate with the number of carbon atoms; however, in CM2 and CM1/2 chondrites, the 13C enrichment decreases with increasing monoamine carbon number. The delta13C values of methylamine in CR2 chondrites ranged from -1 to +10per mille, while in CM2 and CM1/2 chondrites the delta13C values of methylamine ranged from +41 to +59per mille. We also observed racemic compositions of sec-butylamine, 3-methyl-2-butylamine, and sec-pentylamine in the studied carbonaceous chondrites. Additionally, we compared the abundance and delta13C isotopic composition of monoamines to those of their structurally related amino acids. We found that monoamines are less abundant than amino acids in CR2 chondrites, with the opposite being true in CM2 and CM1/2 chondrites. We used these collective data to evaluate different primordial synthetic pathways for monoamines in carbonaceous chondrites and to understand the potential common origins these molecules may share with meteoritic amino acids.

  18. Distribution and Origin of Organic Matter Preserved in Modern Surface Sediments throughout Coastal SE Alaska

    NASA Astrophysics Data System (ADS)

    Walinsky, S.; Prahl, F. G.; Mix, A. C.; Finney, B.

    2006-12-01

    (29)-ene (diploptene). Although the origin of diploptene is yet to be established in the case of SE Alaska, organic matter eroded from soils is the recognized source of this compound in an analogous compositional pattern for hydrocarbons in coastal regions farther south in the Pacific Northwest. Bulk elemental and terrestrial biomarker data clearly show a conflicting perspective on the terrestrial and marine organic matter distribution in sediments from coastal SE Alaska. Resolution of this environmentally intriguing, organic geochemical ambiguity clearly warrants further investigation.

  19. Shock metamorphism of ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Stoeffler, Dieter; Keil, Klaus; Scott, Edward R. D.

    1991-01-01

    This study proposes a revised petrographic classification of progressive stages of shock metamorphism of 26 ordinary chondrites. Six stages of shock (S1 to S6) are defined on the basis of shock effects in olivine and plagioclase as recognized by thin section microscopy, and the characteristic shock effects of each shock stage are described. It is concluded that shock effects and the sequence of progressively increasing degrees of shock metamorphosis are very similar in H, L, and LL groups. Differences in the frequency distribution of shock stages are relatively minor. It is suggested that the collisional histories of the H, L, and LL parent bodies were similar. Petrologic type-3 chondrites are deficient in stages S4 and S6 and, with increasing petrologic type, the frequency of stages S4 to S6 increases. It is suggested that the more porous and volatile-rich Type-3 chondrites are subject to melting at a lower shock pressure than the nonporous chondrites of higher petrologic type. Stage S3 is the most abundant in nearly all petrologic types.

  20. Incompletely compacted equilibrated ordinary chondrites

    SciTech Connect

    Sasso, M.R.; Macke, R.J.; Boesenberg, J.S.; Britt, D.T.; Rovers, M.L.; Ebel, D.S.; Friedrich, J.M.

    2010-01-22

    We document the size distributions and locations of voids present within five highly porous equilibrated ordinary chondrites using high-resolution synchrotron X-ray microtomography ({mu}CT) and helium pycnometry. We found total porosities ranging from {approx}10 to 20% within these chondrites, and with {mu}CT we show that up to 64% of the void space is located within intergranular voids within the rock. Given the low (S1-S2) shock stages of the samples and the large voids between mineral grains, we conclude that these samples experienced unusually low amounts of compaction and shock loading throughout their entire post accretionary history. With Fe metal and FeS metal abundances and grain size distributions, we show that these chondrites formed naturally with greater than average porosities prior to parent body metamorphism. These materials were not 'fluffed' on their parent body by impact-related regolith gardening or events caused by seismic vibrations. Samples of all three chemical types of ordinary chondrites (LL, L, H) are represented in this study and we conclude that incomplete compaction is common within the asteroid belt.

  1. Igneous Graphite in Enstatite Chondrites

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.

    1997-01-01

    Igneous graphite. a rare constituent in terrestrial mafic and ultramafic rocks. occurs in three EH and one EL enstatite chondrite impact-melt breccias as 2-150 Ilm long euhedrallaths. some with pyramidal terminations. In contrast. graphite in most enstatite chondrites exsolved from metallic Fe-Ni as polygonal. rounded or irregular aggregates. Literature data for five EH chondrites on C combusting at high temperatures show that Abee contains the most homogeneous C isotopes (i.e. delta(sup 13)C = -8.1+/-2.1%); in addition. Abee's mean delta(sup l3)C value is the same as the average high-temperature C value for the set of five EH chondrites. This suggests that Abee scavenged C from a plurality of sources on its parent body and homogenized the C during a large-scale melting event. Whereas igneous graphite in terrestrial rocks typically forms at relatively high pressure and only moderately low oxygen fugacity (e.g., approx. 5 kbar. logfO2, approx. -10 at 1200 C ). igneous graphite in asteroidal meteorites formed at much lower pressures and oxygen fugacities.

  2. Igneous Graphite in Enstatite Chondrites

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.

    1997-01-01

    Igneous graphite. a rare constituent in terrestrial mafic and ultramafic rocks. occurs in three EH and one EL enstatite chondrite impact-melt breccias as 2-150 Ilm long euhedrallaths. some with pyramidal terminations. In contrast. graphite in most enstatite chondrites exsolved from metallic Fe-Ni as polygonal. rounded or irregular aggregates. Literature data for five EH chondrites on C combusting at high temperatures show that Abee contains the most homogeneous C isotopes (i.e. delta(sup 13)C = -8.1+/-2.1%); in addition. Abee's mean delta(sup l3)C value is the same as the average high-temperature C value for the set of five EH chondrites. This suggests that Abee scavenged C from a plurality of sources on its parent body and homogenized the C during a large-scale melting event. Whereas igneous graphite in terrestrial rocks typically forms at relatively high pressure and only moderately low oxygen fugacity (e.g., approx. 5 kbar. logfO2, approx. -10 at 1200 C ). igneous graphite in asteroidal meteorites formed at much lower pressures and oxygen fugacities.

  3. Extraterrestrial Amino Acids Identified in Metal-Rich CH and CB Carbonaceous Chondrites from Antarctica

    NASA Technical Reports Server (NTRS)

    Burton, Aaron S.; Elsila, Jamie E.; Hein, Jason E.; Glavin, Daniel P.; Dworkin, Jason P.

    2013-01-01

    Carbonaceous chondrites contain numerous indigenous organic compounds and could have been an important source of prebiotic compounds required for the origin of life on Earth or elsewhere. Extraterrestrial amino acids have been reported in five of the eight groups of carbonaceous chondrites and are most abundant in CI, CM, and CR chondritesbut are also present in the more thermally altered CV and CO chondrites. We report the abundance, distribution, and enantiomeric and isotopic compositions of simple primary amino acids in six metal-rich CH and CB carbonaceous chondrites that have not previously been investigated for amino acids: Allan Hills (ALH) 85085 (CH3), Pecora Escarpment(PCA) 91467 (CH3), Patuxent Range (PAT) 91546 (CH3), MacAlpine Hills (MAC) 02675(CBb), Miller Range (MIL) 05082 (CB), and Miller Range (MIL) 07411 (CB). Amino acid abundances and carbon isotopic values were obtained by using both liquid chromatography time-of-flight mass spectrometry and fluorescence, and gas chromatography isotope ratiomass spectrometry. The (delta D, delta C-13, delta N-15) ratios of multiple amino acids fall outside of the terrestrial range and support their extraterrestrial origin. Extracts of CH chondrites were found to be particularly rich in amino acids (1316 parts per million, ppm) while CB chondrite extracts had much lower abundances (0.22 ppm). The amino acid distributions of the CH and CB chondrites were distinct from the distributions observed in type 2 and 3 CM and CR chondrites and contained elevated levels of beta-, gamma-, and delta-amino acids compared to the corresponding alpha-amino acids, providing evidence that multiple amino acid formation mechanisms were important in CH and CB chondrites.

  4. Partial asteroid differentiation revealed by paleomagnetism of R-chondrite meteorites

    NASA Astrophysics Data System (ADS)

    Cournède, Cécile; Gattacceca, Jérôme; Rochette, Pierre

    2014-05-01

    The study of the paleomagnetism of extraterrestrial material allows constraining magnetic fields in the early solar system. This can help us to understand primordial aspects of the history of the early solar system. Indeed, nebular or solar magnetic fields could have played a major role in the accretion process that generated the primary components of our solar system. Internal fields (i.e. generated by a dynamo within a solid body) are also of substantial interest since they provide information on parent body evolution, especially on parent body differentiation. In this study we focused on Rumuruti chondrites (R chondrites) [1]. This meteorite group is of particular interest because R chondrites parent body is believed to have formed at a heliocentric distance greater than ordinary chondrites and less than carbonaceous chondrites [2]. As such, more than a simple new chondrite group, R chondrites offer the possibility to estimate the magnetic fields strength present in a yet unstudied part of the early solar system. Only preliminary paleomagnetic data are available for these meteorites [3]. We performed a detailed magnetic and paleomagnetic study of two R chondrites, PCA91002 and LAP03639. Our aim was to establish the nature and the origin of the magnetic field recorded in these meteorites. Our results show that these two meteorites contain sulfide (pyrrhotite). Magnetite was also found in PCA91002. Paleomagnetic analyses using thermal and alternating field demagnetization evidenced a stable and homogenous magnetization in both R chondrites. Because magnetic carriers in these meteorites are secondary phases formed during a metamorphic event several Myr after the parent body formation (I-Xe dating on magnetite, [4]), the magnetization was acquired after the possible existence of solar and nebular magnetic fields. Therefore the magnetizing field was most probably of internal origin. Using alternating field normalizing methods we estimate that the magnetization was

  5. Circumstellar and interstellar material in the CO3 chondrite ALHA77307: An isotopic and elemental investigation

    NASA Astrophysics Data System (ADS)

    Bose, Maitrayee; Floss, Christine; Stadermann, Frank J.; Stroud, Rhonda M.; Speck, Angela K.

    2012-09-01

    We have carried out a NanoSIMS C, N and O ion imaging study of the CO3.0 chondrite ALHA77307. The distribution of O-anomalous grains in ALHA77307 is similar to that observed in other primitive meteorites, and is dominated (84%) by 17O-rich Group 1 grains from low-mass asymptotic giant branch (AGB) stars of close-to-solar metallicity. Four percent of the grains belong to Group 2, whose 18O depletions suggest cool-bottom processing in low-mass stars during the AGB phase, while 8% are Group 4 grains with likely origins in Type II supernova (SN) ejecta. One ferromagnesian silicate has a very high 17O enrichment; nova explosions have been suggested as sources for such grains, but recent models with updated reaction rates show large discrepancies with the grain data, leaving the origins of these grains uncertain. Most of the grains are silicates (86%) with the remainder consisting of oxides (8%), three silica grains and two 'composite' grains composed of multiple subgrains with different elemental compositions. The elemental compositions of the silicates are similar to those found in other studies, with a predominance of non-stoichiometric compositions and high (up to 44 at.%) Fe concentrations. A comparison of isotopic and elemental compositions for all presolar silicates shows that olivine compositions are overabundant in Group 4 grains compared to grains from Groups 1 and 2. This may reflect injection of presolar material from a nearby supernova into the early solar nebula and incorporation into parent bodies before alteration of compositions through irradiation and sputtering in the interstellar medium, as is likely to have occurred for the Group 1 and 2 grains from more distant AGB stars. The matrix material in ALHA77307 contains abundant carbonaceous hotspots with excesses in 15N. However, unlike CR chondrites, the insoluble organic matter (IOM) in ALHA77307 does not have a bulk N isotopic anomaly, consistent with Raman evidence that it has experienced more

  6. Surviving High-temperature Components in CI Chondrites

    NASA Technical Reports Server (NTRS)

    Zolensky, M.; Frank, D.

    2014-01-01

    The CI1 chondrites, while having the most solar-like compo-sition of any astromaterial available for laboratory analysis, have also been considerably altered by asteroidal processes including aqueous alteration. It is of fundamental importance to determine their pre-alteration mineralogy, so that the state of matter in the early Solar System can be better determined. In the course of a re-examination of the compositional range of olivine and low-Ca pyroxene in CI chondrites Orgueil, Ivuna and Alais [1] we found the first reported complete CAI, as already reported [2], with at-tached rock consisting mainly of olivine and low-Ca pyroxene. The range of residual olivine major element compositions we have determined in the CIs (Fig. 1) may now be directly com-pared with those of other astromaterials, including Wild 2 grains. The abundance of olivine and low-Ca pyroxene in CIs is higher than is generally appreciated, and in fact much higher than for some CMs [1]. We also noted numerous rounded objects varying in shape from spheres to oblate spheroids, and ranging up to 100µm in size (Fig. 2), which have been previously noted [3] but have not been well documented or appreciated. We characterized the mineralogy by transmission electron microscopy and found that they consist mainly of rather fine-grained, flaky single phase to intergrown serpentine and saponite. These two materials in fact dominate the bulk of the host CI1 chondrites. With the exception of sparse spinels, the rounded phyllosilicate objects are remarka-bly free of other minerals, suggesting that the precursor from which the phyllosilicates were derived was a homogeneous mate-rial. We suggest that these round phyllosilicates aggregates in CI1 chondrites were cryptocrystalline to glassy microchondrules. If so then CI chondrites cannot be considered chondrule-free. Small though they are, the abundance of these putative microchondrules is the same as that of chondrules in the Tagish Lake meteorite.

  7. Bioavailability of dissolved organic matter originating from different sources in the River Vantaa

    NASA Astrophysics Data System (ADS)

    Hoikkala, Laura; Soinne, Helena; Asmala, Eero; Helin, Janne; Autio, Iida; Rahikainen, Mika

    2013-04-01

    Most of the dissolved organic matter (DOM) pool in the Baltic Sea is of terrestrial origin. Organic matter load to the Baltic Sea has been identified as the second greatest environmental pressure both in the Bothnian Bay and in the Gulf of Finland by the HELCOM Holistic Assessment. Loads of terrestrial DOM may increase the productivity, oxygen consumption and light attenuation in the coastal waters. The quantity and quality of DOM loads that enter the Baltic Sea depend on the properties of the catchment area, land use and the runoff as well as ecological processes and water retention time in freshwater systems, and are sensitive to temperature. In this study we investigate DOM loads from River Vantaa, which has a catchment area of 1 685 km2 and flows through the most important population center in Southern Finland into the Gulf of Finland. We focus on the effects of soil type and land-use on the DOM load and on the bioavailability of DOM to bacteria in the Baltic Sea. In addition, samples will be collected from up- and downstream of main water treatment plants to estimate the effect of municipal waste on the DOM loads. Further, we aim to estimate the total DOM loads to the Baltic Sea from samples taken at the river mouth. Water samples are collected from river branches selected according to the main land-use (forest or agricultural land) and soil type (mineral or organic soil) in the catchment area. The DOC, DON and DOP loads will be measured. The bioavailability of DOC is measured by incubating the DOM samples (<0.2 µm) in nutrient replete conditions with bacterial inocula (<0.8 µm, retentate of 100 kD TFF) from either river mouth or the Gulf of Finland for two months at dark. Time courses of DOC and DON concentrations, CDOM absorption and fluorescence, bacterial biomass and respiration will be followed.

  8. Ubiquitous high-FeO silicates in enstatite chondrites

    NASA Technical Reports Server (NTRS)

    Lusby, David; Scott, Edward R. D.; Keil, Klaus

    1987-01-01

    SEM and EMPA were used to determine the mineral contents of four EH3 chondrites. All four showed the dominant enstatite peak, Fs 0-5, with 4-8 percent of FeO-rich pyroxene with Fs 5-20. Among the 542 objects found to contain high-FeO silicates, 18 were chondrules, 381 were rimmed or unrimmed grains, and 143 were aggregates. The high-FeO silicates in these objects are very largely pyroxene with Fs 5-23. Large grains of both FeO-rich and FeO-poor silicates were found to be present in the FeO-rich chondrules. This fact, together with the absence of clasts of FeO-rich chondritic material in the EH3 chondrites, suggests that FeO-rich grains were introduced before or during chondrule formation. It is concluded that FeO-rich and FeO-poor silicates were both present in the nebular region where E chondrites originated.

  9. Amino acid analyses of R and CK chondrites

    NASA Astrophysics Data System (ADS)

    Burton, Aaron S.; McLain, Hannah; Glavin, Daniel P.; Elsila, Jamie E.; Davidson, Jemma; Miller, Kelly E.; Andronikov, Alexander V.; Lauretta, Dante; Dworkin, Jason P.

    2015-03-01

    Exogenous delivery of amino acids and other organic molecules to planetary surfaces may have played an important role in the origins of life on Earth and other solar system bodies. Previous studies have revealed the presence of indigenous amino acids in a wide range of carbon-rich meteorites, with the abundances and structural distributions differing significantly depending on parent body mineralogy and alteration conditions. Here we report on the amino acid abundances of seven type 3-6 CK chondrites and two Rumuruti (R) chondrites. Amino acid measurements were made on hot water extracts from these meteorites by ultrahigh-performance liquid chromatography with fluorescence detection and time-of-flight mass spectrometry. Of the nine meteorites analyzed, four were depleted in amino acids, and one had experienced significant amino acid contamination by terrestrial biology. The remaining four, comprised of two R and two CK chondrites, contained low levels of amino acids that were predominantly the straight chain, amino-terminal (n-ω-amino) acids β-alanine, and γ-amino-n-butyric acid. This amino acid distribution is similar to what we reported previously for thermally altered ureilites and CV and CO chondrites, and these n-ω-amino acids appear to be indigenous to the meteorites and not the result of terrestrial contamination. The amino acids may have been formed by Fischer-Tropsch-type reactions, although this hypothesis needs further testing.

  10. CM and CO chondrites: A common parent body or asteroidal neighbors? Insights from chondrule silicates

    NASA Astrophysics Data System (ADS)

    Schrader, Devin L.; Davidson, Jemma

    2017-10-01

    By investigating the petrology and chemical composition of type II (FeO-rich) chondrules in the Mighei-like carbonaceous (CM) chondrites we constrain their thermal histories and relationship to the Ornans-like carbonaceous (CO) chondrites. We identified FeO-rich relict grains in type II chondrules by their Fe/Mn ratios; their presence indicates chondrule recycling among type II chondrules. The majority of relict grains in type II chondrules are FeO-poor olivine grains. Consistent with previous studies, chemical similarities between CM and CO chondrite chondrules indicate that they had similar formation conditions and that their parent bodies probably formed in a common region within the protoplanetary disk. However, important differences such as mean chondrule size and the lower abundance of FeO-poor relicts in CM chondrite type II chondrules than in CO chondrites suggest CM and CO chondrules did not form together and they likely originate from distinct parent asteroids. Despite being aqueously altered, many CM chondrites contain pre-accretionary anhydrous minerals (i.e., olivine) that are among the least thermally metamorphosed materials in chondrites according to the Cr2O3 content of their ferroan olivine. The presence of these minimally altered pre-accretionary chondrule silicates suggests that samples to be returned from aqueously altered asteroids by the Hayabusa2 and OSIRIS-REx asteroid sample return missions, even highly hydrated, may contain silicates that can provide information about the pre-accretionary histories and conditions of asteroids Ryugu and Bennu, respectively.

  11. On the Relationship between Cosmic Ray Exposure Ages and Petrography of CM Chondrites

    NASA Technical Reports Server (NTRS)

    Takenouchi, A.; Zolensky, M. E.; Nishiizumi, K.; Caffee, M.; Velbel, M. A.; Ross, K.; Zolensky, A.; Lee, L.; Imae, N.; Yamaguchi, A.; hide

    2014-01-01

    Carbonaceous (C) chondrites are potentially the most primitive among chondrites because they mostly escaped thermal metamorphism that affected the other chondrite groups. C chondrites are chemically distinguished from other chondrites by their high Mg/Si ratios and refractory elements, and have experienced various degrees of aqueous alteration. They are subdivided into eight subgroups (CI, CM, CO, CV, CK, CR, CB and CH) based on major element and oxygen isotopic ratios. Their elemental ratios vary over a wide range, in contrast to those of ordinary and enstatite chondrites which are relatively uniform. It is critical to know how many separate bodies are represented by the C chondrites. In this study we defined 4 distinct cosmic-ray exposure (CRE) age groups of CMs and systematically characterized the petrography in each of the 4 CRE age groups to determine whether the groups have significant petrographic differences with such differences probably reflecting different parent body (asteroid) geological processing, or multiple original bodies. We have reported the results of a preliminary grouping at the NIPR Symp. in 2013 [3], however, we revised the grouping and here report our new results.

  12. Carbonates in the Kaidun chondrite. [Abstract only

    NASA Technical Reports Server (NTRS)

    Weisberg, M. K.; Prinz, M.; Zolensky, M. E.; Ivanov, A. V.

    1994-01-01

    Kaidun is a remarkable chondrite breccia fall containing lithic clasts that span a wide range of chondrite groups including C and E chondrites, as well as having clasts with characteristics not yet found in existing chondrite samples. The dominant lithology in Kaidun appears to be CR chondritic, consonant with recent O isotope data. The carbonates in Kaidun are presented as one mineralogical basis for comparing it to the other hydrated chondrites and to better understand its relative alteration history. The four polished thin sections of Kaidun studied contained a variety of lithologies that we classified into four groups -- CR, E, CM-like, and dark inclusions (DIs). DIs contain sulfide and magnetite morphologies that superficially resemble CI chondrites, and some of the previously reported CI lithologies in Kaidun may be what we term DIs. Carbonates were found in all lithologies studied. Carbonates in Kaidun are similar in composition to those in CR chondrites. Some of the DIs in Kaidun, previously characterized as CI, have carbonates similar to those in CR chondrites and are unlike those in CI or CM chondrites. Most carbonates in Kaidun and CR chondrites are calcites, some of which formed at temperatures above 250 C. Dolomite is less common and some may be metastable. Alteration temperatures in the Renazzo CR chondrite were estimated to be approximately 300 C, based on O isotope fractionation between phyllosilicates and magnetite. Temperatures of up to 450 C were proposed for the alteration of a CR-like dark inclusion in Kaidun, based on the presence of hydrothermal pentlandite veins. The alteration temperatures for Kaidun and the other CR chondrites are considerably higher than those suggested for CI or CM parent bodies.

  13. Origins of terrestrial organic matter in surface sediments of the East China Sea shelf

    NASA Astrophysics Data System (ADS)

    Zhang, Hailong; Xing, Lei; Zhao, Meixun

    2017-10-01

    Terrestrial organic matter (TOM) is an important component of marine sedimentary OM, and revealing the origins and transport mechanisms of TOM to the East China Sea (ECS) is important for understanding regional carbon cycle. A novel approach combining molecular proxies and compound-specific carbon isotopes is used to quantitatively constrain the origins and transport mechanisms of TOM in surface sediments from the ECS shelf. The content of terrestrial biomarkers of (C27+C29+C31) n-alkanes (52 to 580 ng g-1) revealed a seaward decreasing trend, the δ13CTOC values (-20.6‰ to -22.7‰) were more negative near the coast, and the TMBR (terrestrial and marine biomarker ratio) values (0.06 to 0.40) also revealed a seaward decreasing trend. These proxies all indicated more TOM (up to 48%) deposition in the coastal areas. The Alkane Index, the ratio of C29/(C29+C31) n-alkanes indicated a higher proportion of grass vegetation in the coastal area; While the δ13C values of C29 n-alkane (-29.3‰ to -33.8‰) indicated that terrestrial plant in the sediments of the ECS shelf were mainly derived from C3 plants. Cluster analysis afforded detailed estimates of different-sourced TOM contributions and transport mechanisms. TOM in the Zhejiang-Fujian coastal area was mostly delivered by the Changjiang River, and characterized by higher %TOM (up to 48%), higher %C3 plant OM (68%-85%) and higher grass plant OM (56%-61%); TOM in the mid-shelf area was mostly transported by aerosols, and characterized by low %TOM (less than 17%), slightly lower C3 plant OM (56%-72%) and lower grass plant OM (49%-55%).

  14. [Identifying the origin of chromophoric dissolved organic matter in Xiamen Bay using fluorescence spectroscopy and chemometrics].

    PubMed

    Lin, Hui; Guo, Wei-Dong; Xu, Jing; Hu, Ming-Hui

    2013-02-01

    The fluorescent components of chromophoric dissolved matter (CDOM) in water samples collected from Xiamen Bay in spring and autumn, 2009 were examined using excitation-emission matrix fluorescence spectroscopy combined with parallel factor analysis (EEMs-PARAFAC). PARAFAC decomposed the fluorescence matrices of CDOM into three humic-like (C1: 250, 345/454 nm; C2: 230, 310/374 nm; C5: 265, 424/478 nm) and two protein-like (C3: 230/342 nm; C4: 230, 275/322 nm) components. Good linear correlation occurred among three humic-like components and between two protein-like components, respectively. This demonstrated that the same types of components (humic-like or protein-like) have similar origin and geochemical behaviors. High abundances of humic-like components were found at the upstream zone of the Jiulong Estuary, while the high abundance of protein-like components occurred at the northern part of semi-enclosed Western Xiamen Harbor. The significant negative correlations were found between the abundances of all fluorescence components and salinity in the estuary area. However, the high contents of chlorophyll a were in line with the high abundances of C3 and C4 in non-estuarine area, which implies that phytoplankton activity could be another important source of protein-like components besides the river runoff. A principal component analysis(PCA) of fluorescent components revealed that terrestrial runoff was the dominant sources of CDOM fluorescence components in Xiamen Bay, while the contribution of the in situ biological processes was relatively lower. This study demonstrates that the combination use of PARAFAC modeling and chemometrics (i. e. PCA) is very useful in identifying the origin of CDOM and quantifying the primary factors influencing their distributions.

  15. Origin of particulate matter pollution episodes in wintertime over the Paris Basin

    NASA Astrophysics Data System (ADS)

    Bessagnet, B.; Hodzic, A.; Blanchard, O.; Lattuati, M.; Le Bihan, O.

    2006-12-01

    Several wintertime pollution events due to particulate matter over the Paris Basin in February and march 2003 are investigated. High pressure systems close to Scandinavia or the North Sea involve very stable conditions with a slight Northeasterly flux on France leading to high airborne pollutant concentrations. In a first step, an evaluation of the CHIMERE model results against observations over the Paris area is proposed. While PM10, nitrate and ammonium seem fairly well reproduced, sulfate concentrations remain difficult to predict. The main objective is to understand the origin of such pollution episodes and to identify the main regions responsible for that using a modeling approach. First, a specific study has been carried out by removing Ile-de-France emissions. During the February 21 and March 21 episodes, the modeling results display an important ammonium nitrate contribution, mainly originating from outside Paris agglomeration. According to the model results, the Paris Basin has also a large influence up to the South West of France. The sensitivity analysis allow to quantify the influence of a region on another, but these numerical results have to be carefully interpreted. In a similar way, an investigation of the possible sources outside France displays a strong influence of emissions from Germany, the Netherlands and Belgium during these episodes. To a lesser extent, Italy has an influence on the Paris area at the end of the episodes. It is also demonstrated that in some situations, the contribution of locally produced or emitted particles is prevalent at the ground level. The influence of French emissions is also studied from March 20 to 25, showing an influence of France on Spain and a strong impact at the end of the episode successively on Great Britain, Belgium, the Netherlands when winds veer Southeast and West. This influence is also significant up to Eastern Europe.

  16. Diamond thermoluminescence properties of different chondrites

    NASA Technical Reports Server (NTRS)

    Fisenko, A. V.; Kashkarov, L. L.; Semjonova, L. F.; Pillinger, C. T.

    1993-01-01

    It was found that thermoluminescence (TL) glows of diamonds depend on the origin of diamonds and the chondrite metamorphism degree. The investigation of TL of diamonds was continued and the results for diamonds from Murchison CM2, Krymka LL3.0, Kainsaz CO3, and Abee E4 were considered. The diamonds synthesized by CVD-process (samples 133, 159) and by detonation from soot (DDS-B14-89) were also analyzed for comparison. Before the TL measuring samples were annealed at approximately 350 C for a few seconds and then irradiated by gamma-rays of Cs-137 up to dose approximately 200 krad. TL-measurements were performed in the air atmosphere on the standard equipment. TL data for samples are shown. TL glow for some diamonds are also presented.

  17. Diamond thermoluminescence properties of different chondrites

    NASA Technical Reports Server (NTRS)

    Fisenko, A. V.; Kashkarov, L. L.; Semjonova, L. F.; Pillinger, C. T.

    1993-01-01

    It was found that thermoluminescence (TL) glows of diamonds depend on the origin of diamonds and the chondrite metamorphism degree. The investigation of TL of diamonds was continued and the results for diamonds from Murchison CM2, Krymka LL3.0, Kainsaz CO3, and Abee E4 were considered. The diamonds synthesized by CVD-process (samples 133, 159) and by detonation from soot (DDS-B14-89) were also analyzed for comparison. Before the TL measuring samples were annealed at approximately 350 C for a few seconds and then irradiated by gamma-rays of Cs-137 up to dose approximately 200 krad. TL-measurements were performed in the air atmosphere on the standard equipment. TL data for samples are shown. TL glow for some diamonds are also presented.

  18. Is extraterrestrial organic matter relevant to the origin of life on Earth?

    PubMed

    Whittet, D C

    1997-06-01

    I review the relative importance of internal and external sources of prebiotic molecules on Earth at the time of life's origin approximately 3.7 Gyr ago. The efficiency of synthesis in the Earth's atmosphere was critically dependent on its oxidation state. If the early atmosphere was non-reducing and CO2-dominated, external delivery might have been the dominant source. Interplanetary dust grains and micrometeorites currently deliver carbonaceous matter to the Earth's surface at a rate of approximately 3 x 10(5) kg/yr (equivalent to a biomass in approximately 2 Gyr), but this may have been as high as 5 x 10(7) kg/yr (a biomass in only approximately 10 Myr) during the epoch of late bombardment. Much of the incoming material is in the form of chemically inactive kerogens and amorphous carbon; but if the Earth once had a dense (approximately 10-bar) atmosphere, small comets rich in a variety of prebiotic molecules may have been sufficiently air-braked to land non-destructively. Lingering uncertainties regarding the impact history of the Earth and the density and composition of its early atmosphere limit our ability to draw firm conclusions.

  19. Secondary Particulate Matter Originating from an Industrial Source and Its Impact on Population Health.

    PubMed

    Mangia, Cristina; Cervino, Marco; Gianicolo, Emilio Antonio Luca

    2015-07-08

    Epidemiological studies have reported adverse associations between long-term exposure to ambient particulate matter (PM2.5) and several health outcomes. One issue in this field is exposure assessment and, in particular, the role of secondary PM2.5, often neglected in environmental and health risk assessment. Thus, the aim of this work was to evaluate the long-term environmental and health impact of primary and secondary PM2.5 concentrations originating from a single industrial source. As a case study, we considered a coal power plant which is a large emitter of both primary PM2.5 and secondary PM2.5 precursors. PM2.5 concentrations were estimated using the Calpuff dispersion model. The health impact was expressed in terms of number of non-accidental deaths potentially attributable to the power plant. Results showed that the estimated secondary PM2.5 extended over a larger area than that related to primary PM2.5 with maximum concentration values of the two components well separated in space. Exposure to secondary PM2.5 increased significantly the estimated number of annual attributable non-accidental deaths. Our study indicates that the impact of secondary PM2.5 may be relevant also at local scale and ought to be considered when estimating the impact of industrial emissions on population health.

  20. Secondary Particulate Matter Originating from an Industrial Source and Its Impact on Population Health

    PubMed Central

    Mangia, Cristina; Cervino, Marco; Gianicolo, Emilio Antonio Luca

    2015-01-01

    Epidemiological studies have reported adverse associations between long-term exposure to ambient particulate matter (PM2.5) and several health outcomes. One issue in this field is exposure assessment and, in particular, the role of secondary PM2.5, often neglected in environmental and health risk assessment. Thus, the aim of this work was to evaluate the long-term environmental and health impact of primary and secondary PM2.5 concentrations originating from a single industrial source. As a case study, we considered a coal power plant which is a large emitter of both primary PM2.5 and secondary PM2.5 precursors. PM2.5 concentrations were estimated using the Calpuff dispersion model. The health impact was expressed in terms of number of non-accidental deaths potentially attributable to the power plant. Results showed that the estimated secondary PM2.5 extended over a larger area than that related to primary PM2.5 with maximum concentration values of the two components well separated in space. Exposure to secondary PM2.5 increased significantly the estimated number of annual attributable non-accidental deaths. Our study indicates that the impact of secondary PM2.5 may be relevant also at local scale and ought to be considered when estimating the impact of industrial emissions on population health. PMID:26184247

  1. The origin of the extragalactic gamma-ray background and implications for dark matter annihilation

    SciTech Connect

    Ajello, M.; Gasparrini, D.; Sánchez-Conde, M.; Zaharijas, G.; Gustafsson, M.; Cohen-Tanugi, J.; Dermer, C. D.; Inoue, Y.; Hartmann, D.; Ackermann, M.; Bechtol, K.; Franckowiak, A.; Reimer, A.; Romani, R. W.; Strong, A. W.

    2015-02-19

    The origin of the extragalactic γ-ray background (EGB) has been debated for some time. The EGB comprises the γ-ray emission from resolved and unresolved extragalactic sources, such as blazars, star-forming galaxies, and radio galaxies, as well as radiation from truly diffuse processes. This Letter focuses on the blazar source class, the most numerous detected population, and presents an updated luminosity function and spectral energy distribution model consistent with the blazar observations performed by the Fermi-Large Area Telescope (LAT). Additionally, we show that blazars account for 50$_{-11}^{+12}$% of the EGB photons (>0.1 GeV), and that Fermi-LAT has already resolved ~70% of this contribution. Blazars, and in particular hard-spectrum sources such as BL Lacs, are responsible for most of the EGB emission above 100 GeV. We find that the extragalactic background light, which attenuates blazars' high-energy emission, is responsible for the high-energy cutoff observed in the EGB spectrum. Finally, we show that blazars, star-forming galaxies, and radio galaxies can naturally account for the amplitude and spectral shape of the background in the 0.1–820 GeV range, leaving only modest room for other contributions. In conclusion, this allows us to set competitive constraints on the dark matter annihilation cross section.

  2. The origin of the extragalactic gamma-ray background and implications for dark matter annihilation

    DOE PAGES

    Ajello, M.; Gasparrini, D.; Sánchez-Conde, M.; ...

    2015-02-19

    The origin of the extragalactic γ-ray background (EGB) has been debated for some time. The EGB comprises the γ-ray emission from resolved and unresolved extragalactic sources, such as blazars, star-forming galaxies, and radio galaxies, as well as radiation from truly diffuse processes. This Letter focuses on the blazar source class, the most numerous detected population, and presents an updated luminosity function and spectral energy distribution model consistent with the blazar observations performed by the Fermi-Large Area Telescope (LAT). Additionally, we show that blazars account for 50more » $$_{-11}^{+12}$$% of the EGB photons (>0.1 GeV), and that Fermi-LAT has already resolved ~70% of this contribution. Blazars, and in particular hard-spectrum sources such as BL Lacs, are responsible for most of the EGB emission above 100 GeV. We find that the extragalactic background light, which attenuates blazars' high-energy emission, is responsible for the high-energy cutoff observed in the EGB spectrum. Finally, we show that blazars, star-forming galaxies, and radio galaxies can naturally account for the amplitude and spectral shape of the background in the 0.1–820 GeV range, leaving only modest room for other contributions. In conclusion, this allows us to set competitive constraints on the dark matter annihilation cross section.« less

  3. Origin of particulate matter pollution episodes in wintertime over the Paris Basin

    NASA Astrophysics Data System (ADS)

    Bessagnet, B.; Hodzic, A.; Blanchard, O.; Lattuati, M.; Le Bihan, O.; Marfaing, H.; Rouïl, L.

    Several wintertime pollution events due to particulate matter on the Paris Basin in 2003 are investigated in this paper. High-pressure systems close to Scandinavia or the North Sea involve highly stable conditions with slight Northeasterly flux on France leading to high airborne pollutant concentrations. An evaluation of the CHIMERE model results against observations over the Paris area is proposed. While PM 10, nitrate and ammonium seem fairly well reproduced, sulfate concentrations remain difficult to predict. A specific study, by removing Ile-de-France emissions, displays on 21 February and 21 March episodes an important ammonium nitrate contribution, mainly originating from outside the Paris area. According to the model results, the Paris Basin has also a large influence up to the Southwest of France. In a similar way, an investigation of the possible sources outside the Paris basin, displays a strong influence of emissions from Germany, the Netherlands and Belgium during these episodes. To a lesser extent, Italy has an influence on the Paris area at the end of the episodes. It is also demonstrated that in some situations, the contribution of locally produced or emitted particles is prevalent at the ground level. The influence of French emissions is also studied from 20 to 25 March displaying an influence on Spain and a strong impact at the end of the episode successively on Great Britain, Belgium, the Netherlands when winds veer Southeast and West. This influence is also significant up to Eastern Europe.

  4. White matter hyperintensities of presumed vascular origin: a population-based study in rural Ecuador (The Atahualpa Project).

    PubMed

    Del Brutto, Oscar H; Mera, Robertino M; Del Brutto, Victor J; Zambrano, Mauricio; Lama, Julio

    2015-04-01

    Cerebral small vessel disease is probably one of the most common pathogenetic mechanisms underlying stroke in Latin America. However, the importance of silent markers of small vessel disease, including white matter hyperintensities of presumed vascular origin, has not been assessed so far. The study aims to evaluate prevalence and correlates of white matter hyperintensities in community-dwelling elders living in Atahualpa (rural Ecuador). Atahualpa residents aged ≥ 60 years were identified during a door-to-door survey and invited to undergo brain magnetic resonance imaging for identification and grading white matter hyperintensities and other markers of small vessel disease. Using multivariate logistic regression models, we evaluated whether white matter hyperintensities is associated with demographics, cardiovascular health status, stroke, cerebral microbleeds, and cortical atrophy, after adjusting for the other variables. Out of 258 enrolled persons (mean age, 70 ± 8 years; 59% women), 172 (67%) had white matter hyperintensities, which were moderate to severe in 63. Analyses showed significant associations of white matter hyperintensities presence and severity with age and cardiovascular health status, as well as with overt and silent strokes, and a trend for association with cerebral microbleeds and cortical atrophy. Prevalence and correlates of white matter hyperintensities in elders living in rural Ecuador is almost comparable with that reported from industrialized nations, reinforcing the concept that the burden of small vessel disease is on the rise in underserved Latin American populations. © 2014 World Stroke Organization.

  5. Search for EPR markers of the history and origin of the insoluble organic matter in extraterrestrial and terrestrial rocks.

    PubMed

    Gourier, Didier; Binet, Laurent; Scrzypczak, Audrey; Derenne, Sylvie; Robert, François

    2004-05-01

    The insoluble organic matter (IOM) of three carbonaceous meteorites (Orgueil, Murchison and Tagish Lake meteorites) and three samples of cherts (microcrystalline SiO2 rock) containing microfossils with age ranging between 45 million years and 3.5 billion years is studied by electron paramagnetic resonance (EPR). The age of the meteorites is that of the solar system (4.6 billion years). The purpose of this work was to determine the EPR parameters, which allow us to discriminate between biogenic and extra terrestrial origin for the organic matter. Such indicators should be relevant for the controversy regarding the biogenicity of the organic matter in the oldest cheroot (3.5 billion years) and in Martian meteorites containing microbe-like microstructures. The organic matter of meteorites contains a high concentration of diradicaloid moieties characterised by a diamagnetic ground state S = 0 and a thermally accessible triplet state S = 1. The three meteorites exhibit the same singlet-triplet gap (ST gap) DeltaE approximately 0.1 eV. To the best of our knowledge, such diradicaloids are unknown in insoluble organic matter of terrestrial origin. We have also shown that the EPR linewidth of insoluble organic matter in cherts and coals decrease logarithmically with the age of the organic matter. We conclude from this result that the organic matter in the oldest cherts (3.5 billion years) has the same age as their SiO2 matrix, and is not due to a latter contamination by bacteria, as was recently found in meteoritic samples.

  6. The Steingarden Nunataks L6 Chondrites STG 07002, 07003, 07004: Relationship to Type 7 Chondrites

    NASA Astrophysics Data System (ADS)

    Brandstätter, F.; Koeberl, C.; Topa, D.

    2014-09-01

    Steingarden Nunataks L6 chondrites STG 07002, 07003 and 07004 have several features in common with some recently described L7 chondrites. The similarities comprise microscopic textures as well as the mineral chemistry of major silicates and opaques.

  7. Hydrogen isotopic composition of the water in CR chondrites

    NASA Astrophysics Data System (ADS)

    Bonal, L.; Alexander, C. M. O.'D.; Huss, G. R.; Nagashima, K.; Quirico, E.; Beck, P.

    2013-04-01

    The thermal and aqueous alteration experienced by QUE 99177, MET 00426, EET 92042, GRA 95229, Renazzo and Al Rais CR chondrites was assessed through multi-technique characterization of their the carbonaceous matter and hydrated mineral phases. Each of the chondrites escaped long duration thermal metamorphism as reflected by the low structural order of the polyaromatic carbonaceous matter assessed by Raman spectroscopy. The infrared spectra of the matrix grains clearly reveal the presence of hydrated minerals in each of the CR chondrites. In particular, the extent of aqueous alteration experienced by QUE 99177 and MET 00426 may have been previously underestimated. The H isotopic compositions of the altering fluids were measured in situ in fine-grained phyllosilicates and individual coarse-grained hydrated silicates. In the analyzed CR chondrites, the main observations are that (i) the water is systematically enriched in D, and the enrichments (δDwater up to 1600‰) can be even higher than the highest D-enrichments reported for cometary water; (ii) the isotopic composition of the water is highly variable at the micrometer scale; (iii) there is no clear trend observed in the isotopic composition of the water (maximum D-enrichment, range of variation) along the aqueous alteration sequence. The D-enrichments and spatial variability are easier to explain as secondary signatures acquired through parent body processes, rather than as being due to the accretion of at least two ices with distinct isotopic compositions and sources that did not fully mix when they melted at the start of the aqueous alteration process.

  8. Effect of metamorphism on isolated olivine grains in CO3 chondrites

    NASA Technical Reports Server (NTRS)

    Jones, Rhian H.

    1993-01-01

    The presence of a metamorphic sequence in the CO3 chondrite group has been shown previously to result in changes in properties of chondrule silicates. However, the role of isolated olivine grains during metamorphism of these chondrites has not been addressed. Isolated olivine grains in two metamorphosed CO3 chondrites, Lance and Isna, have been investigated in this study in order to assess the compositional properties of isolated olivine grains that may be attributable to metamorphism. Compositional changes in isolated olivines with increasing petrologic subtype are very similar to changes in chondrule olivines in the same chondrites. Olivine compositions from all occurrences (chondrules, isolated grains, and matrix) converge with increasing petrologic subtype. The degree of equilibration of minor elements is qualitatively related to the diffusion rate of each element in olivine, suggesting that diffusion-controlled processes are the most important processes responsible for compositional changes within the metamorphic sequence. The data are consistent with metamorphism taking place in a closed system on the CO3 chondrite parent body. Fe-poor olivine grains in metamorphosed chondrites are characterized by an Fe-rich rim, which is the result of diffusion of Fe into the grains from Fe-rich matrix. In some instances, 'complex', Fe-rich rims have been identified, which appear to have originated as igneous overgrowths and subsequently to have been overprinted by diffusion processes during metamorphism. Processes experienced by CO3 chondrites are more similar to those experienced by the ordinary chondrites than to those encountered by other carbonaceous chondrites, such as the CV3 group.

  9. Effect of metamorphism on isolated olivine grains in CO3 chondrites

    NASA Astrophysics Data System (ADS)

    Jones, R. H.

    1993-06-01

    The presence of a metamorphic sequence in the CO3 chondrite group has been shown previously to result in changes in properties of chondrule silicates. However, the role of isolated olivine grains during metamorphism of these chondrites has not been addressed. Isolated olivine grains in two metamorphosed CO3 chondrites, Lance and Isna, have been investigated in this study in order to assess the compositional properties of isolated olivine grains that may be attributable to metamorphism. Compositional changes in isolated olivines with increasing petrologic subtype are very similar to changes in chondrule olivines in the same chondrites. Olivine compositions from all occurrences (chondrules, isolated grains, and matrix) converge with increasing petrologic subtype. The degree of equilibration of minor elements is qualitatively related to the diffusion rate of each element in olivine, suggesting that diffusion-controlled processes are the most important processes responsible for compositional changes within the metamorphic sequence. The data are consistent with metamorphism taking place in a closed system on the CO3 chondrite parent body. Fe-poor olivine grains in metamorphosed chondrites are characterized by an Fe-rich rim, which is the result of diffusion of Fe into the grains from Fe-rich matrix. In some instances, 'complex', Fe-rich rims have been identified, which appear to have originated as igneous overgrowths and subsequently to have been overprinted by diffusion processes during metamorphism. Processes experienced by CO3 chondrites are more similar to those experienced by the ordinary chondrites than to those encountered by other carbonaceous chondrites, such as the CV3 group.

  10. Spectral reflectance properties of carbonaceous chondrites - 5: CO chondrites

    NASA Astrophysics Data System (ADS)

    Cloutis, E. A.; Hudon, P.; Hiroi, T.; Gaffey, M. J.; Mann, P.

    2012-08-01

    We examined the spectral reflectance properties of 16 CO-type carbonaceous chondrites (CCs) in order to better understand their range of spectral properties, develop spectral-compositional correlations, and provide information that may aid in the search for CO parent bodies. As a group, our CO powder spectra have some similarities and differences. COs have experienced varying degree of thermal metamorphism, with petrologic subgrades ranging from ˜CO3.0 to ˜CO3.8. Their reflectance spectra are characterized by a ubiquitous absorption feature in the 1 μm region, and a nearly ubiquitous feature in the 2 μm region that appears in CO >3.1 spectra. The 1 μm region feature is attributable to abundant Fe-bearing amorphous phases (and Fe-poor olivine) in the lower petrologic subtypes, which gradually transforms to more abundant and Fe-rich olivine with increasing metamorphism. The increase in depth and decrease in wavelength position of this feature are consistent with this transformation. All but the least-altered COs also exhibit an absorption feature in the 2 μm region whose depth also generally increases with increasing metamorphic grade, resulting in increasingly blue-sloped spectra and larger band area ratios. The wavelength position and change in depth of this feature (ranging from 0% to 12.2%) is consistent with increasing Fe2+ in spinel, which is present in calcium-aluminum and ameboid olivine inclusions. Reflectance of a local reflectance maximum near 0.8 μm increases with increasing thermal metamorphism and this is likely due to the loss and aggregation of carbonaceous phases. The increasing reflectance is negatively correlated with various measures of spectral slope (i.e., brighter = bluer), and while this cannot be uniquely attributed to any one cause, it is consistent with increasing spinel Fe2+ content and decreasing carbonaceous material abundance or aggregation. With decreasing grain size, CO spectra normally become brighter and more red-sloped. The

  11. Magnetic record in chondrite meteorites

    NASA Technical Reports Server (NTRS)

    Wasilewski, P. J.; Faris, J. L.; Obryan, M. V.

    1993-01-01

    What we know about the magnetic record in chondrite meteorites based on new data and previously published results is summarized. Strips from thin slabs of chondrite meteorites were cut into near cubical subsamples (several mm on edge) numbering approximately 60 to approximately 120 per meteorite. A common orientation was assigned to each subsample from a given meteorite in order to ensure that we could discover the vector makeup of the bulk meteorite. The new data set includes: Shaw (L7), Roy (L5/6), Claytonville (L5), Plainview (H5), Etter (H5), Leoville (C3V), and Allende (C3V). In addition to these new results, literature data of sufficient detail, e.g. Bjurbole (L4), ALH769 (L6), Abee (E4), Allende (C3V), and Olivenza (L5), is considered.

  12. Magnetic record in chondrite meteorites

    NASA Technical Reports Server (NTRS)

    Wasilewski, P. J.; Faris, J. L.; Obryan, M. V.

    1993-01-01

    What we know about the magnetic record in chondrite meteorites based on new data and previously published results is summarized. Strips from thin slabs of chondrite meteorites were cut into near cubical subsamples (several mm on edge) numbering approximately 60 to approximately 120 per meteorite. A common orientation was assigned to each subsample from a given meteorite in order to ensure that we could discover the vector makeup of the bulk meteorite. The new data set includes: Shaw (L7), Roy (L5/6), Claytonville (L5), Plainview (H5), Etter (H5), Leoville (C3V), and Allende (C3V). In addition to these new results, literature data of sufficient detail, e.g. Bjurbole (L4), ALH769 (L6), Abee (E4), Allende (C3V), and Olivenza (L5), is considered.

  13. Rare-earth abundances in chondritic meteorites

    NASA Technical Reports Server (NTRS)

    Evensen, N. M.; Hamilton, P. J.; Onions, R. K.

    1978-01-01

    Fifteen chondrites, including eight carbonaceous chondrites, were analyzed for rare earth element abundances by isotope dilution. Examination of REE for a large number of individual chondrites shows that only a small proportion of the analyses have flat unfractionated REE patterns within experimental error. While some of the remaining analyses are consistent with magmatic fractionation, many patterns, in particular those with positive Ce anomalies, can not be explained by known magmatic processes. Elemental abundance anomalies are found in all major chondrite classes. The persistence of anomalies in chondritic materials relatively removed from direct condensational processes implies that anomalous components are resistant to equilibrium or were introduced at a late stage of chondrite formation. Large-scale segregation of gas and condensate is implied, and bulk variations in REE abundances between planetary bodies is possible.

  14. Rare-earth abundances in chondritic meteorites

    NASA Technical Reports Server (NTRS)

    Evensen, N. M.; Hamilton, P. J.; Onions, R. K.

    1978-01-01

    Fifteen chondrites, including eight carbonaceous chondrites, were analyzed for rare earth element abundances by isotope dilution. Examination of REE for a large number of individual chondrites shows that only a small proportion of the analyses have flat unfractionated REE patterns within experimental error. While some of the remaining analyses are consistent with magmatic fractionation, many patterns, in particular those with positive Ce anomalies, can not be explained by known magmatic processes. Elemental abundance anomalies are found in all major chondrite classes. The persistence of anomalies in chondritic materials relatively removed from direct condensational processes implies that anomalous components are resistant to equilibrium or were introduced at a late stage of chondrite formation. Large-scale segregation of gas and condensate is implied, and bulk variations in REE abundances between planetary bodies is possible.

  15. Multiple and fast: The accretion of ordinary chondrite parent bodies

    SciTech Connect

    Vernazza, P.; Barge, P.; Zanda, B.; Hewins, R.; Binzel, R. P.; DeMeo, F. E.; Lockhart, M.; Hiroi, T.; Birlan, M.; Ricci, L.

    2014-08-20

    Although petrologic, chemical, and isotopic studies of ordinary chondrites and meteorites in general have largely helped establish a chronology of the earliest events of planetesimal formation and their evolution, there are several questions that cannot be resolved via laboratory measurements and/or experiments alone. Here, we propose the rationale for several new constraints on the formation and evolution of ordinary chondrite parent bodies (and, by extension, most planetesimals) from newly available spectral measurements and mineralogical analysis of main-belt S-type asteroids (83 objects) and unequilibrated ordinary chondrite meteorites (53 samples). Based on the latter, we suggest that spectral data may be used to distinguish whether an ordinary chondrite was formed near the surface or in the interior of its parent body. If these constraints are correct, the suggested implications include that: (1) large groups of compositionally similar asteroids are a natural outcome of planetesimal formation and, consequently, meteorites within a given class can originate from multiple parent bodies; (2) the surfaces of large (up to ∼200 km) S-type main-belt asteroids mostly expose the interiors of the primordial bodies, a likely consequence of impacts by small asteroids (D < 10 km) in the early solar system; (3) the duration of accretion of the H chondrite parent bodies was likely short (instantaneous or in less than ∼10{sup 5} yr, but certainly not as long as 1 Myr); (4) LL-like bodies formed closer to the Sun than H-like bodies, a possible consequence of the radial mixing and size sorting of chondrules in the protoplanetary disk prior to accretion.

  16. Forming Chondrites in a Solar Nebula with Magnetically Induced Turbulence

    NASA Astrophysics Data System (ADS)

    Hasegawa, Yasuhiro; Turner, Neal J.; Masiero, Joseph; Wakita, Shigeru; Matsumoto, Yuji; Oshino, Shoichi

    2016-03-01

    Chondritic meteorites provide valuable opportunities to investigate the origins of the solar system. We explore impact jetting as a mechanism of chondrule formation and subsequent pebble accretion as a mechanism of accreting chondrules onto parent bodies of chondrites, and investigate how these two processes can account for the currently available meteoritic data. We find that when the solar nebula is ≤5 times more massive than the minimum-mass solar nebula at a ≃ 2-3 au and parent bodies of chondrites are ≤1024 g (≤500 km in radius) in the solar nebula, impact jetting and subsequent pebble accretion can reproduce a number of properties of the meteoritic data. The properties include the present asteroid belt mass, the formation timescale of chondrules, and the magnetic field strength of the nebula derived from chondrules in Semarkona. Since this scenario requires a first generation of planetesimals that trigger impact jetting and serve as parent bodies to accrete chondrules, the upper limit of parent bodies’ masses leads to the following implications: primordial asteroids that were originally ≥1024 g in mass were unlikely to contain chondrules, while less massive primordial asteroids likely had a chondrule-rich surface layer. The scenario developed from impact jetting and pebble accretion can therefore provide new insights into the origins of the solar system.

  17. Forming Chondrites in a Solar Nebula with Magnetically Induced Turbulence

    NASA Astrophysics Data System (ADS)

    Hasegawa, Yasuhiro; Turner, Neal J.; Masiero, Joseph R.

    2016-10-01

    Chondritic meteorites provide valuable opportunities to investigate origins of the solar system. We explore impact jetting as a mechanism to form chondrules and subsequent pebble accretion as a mechanism to accrete them onto parent bodies of chondrites, and investigate how these two processes can account for the currently available meteoritic data. We find that when the solar nebula is < 5 times more massive than the minimum-mass solar nebula at a = 2-3 AU and parent bodies of chondrites are < 1024 g (< 500 km in radius) there, impact jetting and subsequent pebble accretion can reproduce a number of properties of the meteoritic data. The properties include the present asteroid belt mass, formation timescale of chondrules, and the magnetic field strength of the nebula derived from chondrules in Semarkona. Since this scenario requires a first generation of planetesimals that trigger impact jetting and serve as parent bodies to accrete chondrules, the upper limit of parent bodies' mass leads to the following implications: primordial asteroids that were originally >1024 g in mass were unlikely to contain chondrules, while less massive primordial asteroids likely had a chondrule-rich surface layer. The scenario developed from impact jetting and pebble accretion can therefore provide new insights into origins of the solar system.

  18. FORMING CHONDRITES IN A SOLAR NEBULA WITH MAGNETICALLY INDUCED TURBULENCE

    SciTech Connect

    Hasegawa, Yasuhiro; Turner, Neal J.; Masiero, Joseph; Wakita, Shigeru; Matsumoto, Yuji; Oshino, Shoichi

    2016-03-20

    Chondritic meteorites provide valuable opportunities to investigate the origins of the solar system. We explore impact jetting as a mechanism of chondrule formation and subsequent pebble accretion as a mechanism of accreting chondrules onto parent bodies of chondrites, and investigate how these two processes can account for the currently available meteoritic data. We find that when the solar nebula is ≤5 times more massive than the minimum-mass solar nebula at a ≃ 2–3 au and parent bodies of chondrites are ≤10{sup 24} g (≤500 km in radius) in the solar nebula, impact jetting and subsequent pebble accretion can reproduce a number of properties of the meteoritic data. The properties include the present asteroid belt mass, the formation timescale of chondrules, and the magnetic field strength of the nebula derived from chondrules in Semarkona. Since this scenario requires a first generation of planetesimals that trigger impact jetting and serve as parent bodies to accrete chondrules, the upper limit of parent bodies’ masses leads to the following implications: primordial asteroids that were originally ≥10{sup 24} g in mass were unlikely to contain chondrules, while less massive primordial asteroids likely had a chondrule-rich surface layer. The scenario developed from impact jetting and pebble accretion can therefore provide new insights into the origins of the solar system.

  19. Accretional Impact Melt From the L-Chondrite Parent Body

    NASA Astrophysics Data System (ADS)

    Wittmann, A.; Weirich, J. R.; Swindle, T. D.; Rumble, D.; Kring, D. A.

    2009-05-01

    MIL 05029, a unique achondritic Antarctic meteorite with L-chondritic affinity, has a medium-grained, well equilibrated texture of large poikilitic low-Ca pyroxenes that overgrew smaller, euhedral olivines. Plagioclase filled interstitial spaces and has an abundance that is twice that typical for L-chondrites, while Fe-Ni metal and troilite are strongly depleted in that respect. No relic clasts or shock features were found in the thin section analyzed. However, based on its chemical affinity to L-chondrites, MIL 05029 was classified as an impact melt. This is confirmed by its olivine and low-Ca pyroxene compositions, the Co content in Fe-Ni metal, and its oxygen isotopic composition that lies very close to that of L-chondrites. An igneous origin of MIL 05029 cannot be ruled out but would have to be reconciled with thermochronometric constraints for the formation of the ordinary chondrite parent bodies. These studies infer delayed accretion of the parent asteroids of the ordinary chondrites and, thus, insufficient heating from short-lived radiogenic isotopes to produce endogenic magmatism. Metallographic cooling rates of ˜2-22 °C/Ma in the temperature range between ˜700-400°C were determined on five zoned metal particles of MIL 05029. Thermal modeling showed that such cooling rates relate to metamorphic conditions at depths of 5-12 km on the L-chondrite parent body. For an impact to deposit material at this depth, scaling relationships for an impact event on the 100-200 km diameter parent asteroid require a 15 to 60 km diameter simple crater that produced a basal melt pool, in which MIL 05029 crystallized. Further constraints for the formation conditions of MIL 05029 were derived from three whole-rock samples that gave well-defined Ar-Ar plateau ages of 4.53±0.02 Ga. This age indicates the time at which MIL 05029 cooled below ˜180°C, the Ar-closure temperature of plagioclase. Considering its slow metallographic cooling, the impact event that formed MIL 05029

  20. Metallic copper in ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.

    1994-01-01

    Metallic Cu of moderately high purity (approximately 985 mg/g Cu, approximately 15 mg/g Ni) occurs in at least 66% of ordinary chondrites (OC) as heterogeneously distributed, small (typically less than or equal to 20 micrometers) rounded to irregular grains. The mean modal abundance of metallic Cu in H, L and LL chondrites is low: 1.0 to 1.4 x 10(exp -4) vol%, corresponding to only 4 - 5 % of the total Cu in OC whole rocks. In more than 75% of the metallic-Cu-bearing OC, at least some metallic Cu occurs at metallic-Fe-Ni-troilite grain boundaries. In some cases it also occurs within troilite, within metallic Fe-Ni, or at the boundaries these phases form with silicates or chromite. Ordinary chondrites that contain a relatively large number of occurrences of metallic Cu/sq mm have a tendency to have experienced moderately high degrees of shock. Shock processes can cause local melting and transportation of metallic Fe-Ni and troilte; because metallic Cu is mainly associated with these phases, it also gets redistributed during shock events. In the most common petrographic assemblage containing metallic Cu, the Cu is adjacent to small irregular troilite grains surrounded by taenite plus tetrataenite; this assemblage resembles fizzed troilite and may have formed by localized shock melting or remelting of a metal-troilite assemblage.

  1. Metallic copper in ordinary chondrites

    NASA Astrophysics Data System (ADS)

    Rubin, A. E.

    1994-01-01

    Metallic Cu of moderately high purity (approximately 985 mg/g Cu, approximately 15 mg/g Ni) occurs in at least 66% of ordinary chondrites (OC) as heterogeneously distributed, small (typically less than or equal to 20 micrometers) rounded to irregular grains. The mean modal abundance of metallic Cu in H, L and LL chondrites is low: 1.0 to 1.4 x 10-4 vol%, corresponding to only 4 - 5 % of the total Cu in OC whole rocks. In more than 75% of the metallic-Cu-bearing OC, at least some metallic Cu occurs at metallic-Fe-Ni-troilite grain boundaries. In some cases it also occurs within troilite, within metallic Fe-Ni, or at the boundaries these phases form with silicates or chromite. Ordinary chondrites that contain a relatively large number of occurrences of metallic Cu/sq mm have a tendency to have experienced moderately high degrees of shock. Shock processes can cause local melting and transportation of metallic Fe-Ni and troilte; because metallic Cu is mainly associated with these phases, it also gets redistributed during shock events. In the most common petrographic assemblage containing metallic Cu, the Cu is adjacent to small irregular troilite grains surrounded by taenite plus tetrataenite; this assemblage resembles fizzed troilite and may have formed by localized shock melting or remelting of a metal-troilite assemblage.

  2. Oxidation during metamorphism of the ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Mcsween, Harry Y., Jr.; Labotka, Theodore C.

    1993-01-01

    It is suggested that some current concepts about the conditions of metamorphism in ordinary chondrites may be flawed. These meteorites display small systematic variations in the oxidation state of Fe. Evidence is presented that oxidation of Fe is linked to metamorphic grade in types 4-6 ordinary chondrites. This conclusion is at variance with a commonly accepted model for chondrite metamorphism that assumes Fe reduction by graphite.

  3. High-temperature condensates in carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Grossman, L.

    1977-01-01

    Equilibrium thermodynamic calculations of the sequence of condensation of minerals from a cooling gas of solar composition play an important role in explaining the mineralogy and trace element content of different types of inclusions in carbonaceous chondrites. Group IV B iron meteorites and enstatite chondrites may also be direct condensates from the solar nebula. Condensation theory provides a framework within which chemical fractionations between different classes of chondrites may be understood.

  4. Northwest Africa 5958: A weakly altered CM-related ungrouped chondrite, not a CI3

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    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 multitechnique 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 ∆'17O = -4.3‰, 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.

  5. Shock Vein in an Enstatite Chondrite, Asuka 10164

    NASA Astrophysics Data System (ADS)

    Kimura, M.; Yamaguchi, A.; Miyahara, M.; Pittarello, L.

    2014-09-01

    In the vein of an EH3 chondrite, we found coesite. This is the first discovery of a high-pressure phase in E chondrites. Our results suggest that all major chondrite groups contain high-pressure polymorphs.

  6. Silica-bearing objects in the Dengli H3.8 and Gorlovka H3-4 chondrites

    NASA Technical Reports Server (NTRS)

    Ivanova, M. A.; Kononkova, N. N.; Petaev, M. I.

    1993-01-01

    Silica-bearing objects are enigmatic components of the olivine-normative ordinary chondrites. Several papers have been devoted to the study of these objects in various chondrite types. While a relatively large body of information has been collected, the origin of these objects is still controversial. Here we report new data on silica-bearing objects in the unequilibrated H-chondrites Dengli and Gorlovka. The crystallization history of these objects could be explained on the basis of the phase diagram of the Q-Ol-Pl (Al2O3) system, but the origin of the silica-rich liquids remains unclear.

  7. Parent-Body Modification of Chondritic Meteorites

    NASA Technical Reports Server (NTRS)

    Rubin, Alan

    2003-01-01

    This proposal focused on the parent-body modification of chondritic materials and substantial progress was made in the last year. A summary of the work accomplished during this period is discussed. The topics include: 1) Chromite-Plagioclase Assemblages in Ordinary Chondrites; 2) The Gujba Bencubbin-like meteorite fall; 3) NWA428: A rock that Experienced Impact-induced Annealing; 4) Spade: An Annealed H-chondrite Impact-melt Breccia; and 5) Post-shock Annealing in Ordinary Chondrites. A list of the papers submitted or published during the period is also presented.

  8. Testing the dark matter origin of the WMAP-Planck haze with radio observations of spiral galaxies

    SciTech Connect

    Carlson, Eric; Linden, Tim; Profumo, Stefano; Hooper, Dan E-mail: dhooper@fnal.gov E-mail: profumo@ucsc.edu

    2013-07-01

    If the Galactic WMAP radio haze, as recently confirmed by Planck, is produced by dark matter annihilation or decay, similar diffuse radio halos should exist around other galaxies with physical properties comparable to the Milky Way. If instead the haze is due to an astrophysical mechanism peculiar to the Milky Way or to a transient event, a similar halo need not exist around all Milky Way ''twins''. We use radio observations of 66 spiral galaxies to test the dark matter origin of the haze. We select galaxies based on morphological type and maximal rotational velocity, and obtain their luminosities from a 1.49 GHz catalog and additional radio observations at other frequencies. We find many instances of galaxies with radio emission that is less than 5% as bright as naively expected from dark matter models that could produce the Milky Way haze, and at least 3 galaxies that are less than 1% as bright as expected, assuming dark matter distributions, magnetic fields, and cosmic ray propagation parameters equal to those of the Milky Way. For reasonable ranges for the variation of these parameters, we estimate the fraction of galaxies that should be expected to be significantly less bright in radio, and argue that this is marginally compatible with the observed distribution. While our findings therefore cannot rule out a dark matter origin for the radio haze at this time, we find numerous examples (including the Andromeda Galaxy) where, if dark matter is indeed the origin of the Milky Way haze, some mechanism must be in place to suppress the corresponding haze of the external galaxy. We point out that Planck data will offer opportunities to improve this type of constraint in a highly relevant frequency range and for a potentially larger set of candidate galaxies.

  9. Microbial origin of fluorescent dissolved organic matter: bacterial species fluorescence signatures

    NASA Astrophysics Data System (ADS)

    Fox, Bethany; Thorn, Robin; Turner, Dann; Anesio, Alexandre; Reynolds, Darren

    2017-04-01

    Dissolved organic matter (DOM) is ubiquitous in aquatic systems, undertaking an essential role in global biogeochemical cycling (Hudson et al. 2007). Recent research has seen the increasing use of fluorescence spectroscopy for monitoring naturally occurring fluorescent DOM (FDOM), with advances in the technology and in the analysis of data leading to an improved understanding of the interactions between the ecosystem and FDOM (Hudson et al. 2008, Carstea 2010). This work has defined the origins of FDOM as autochthonous, produced in situ, often termed 'microbially derived', and allochthonous, transported into the system from external source, often termed 'terrestrially sourced' (Coble et al. 2014). Previously at EGU we have presented research that has explored microbial processing and production of Peak T, an autochthonous FDOM peak. Within this work we have identified the autochthonous production of a range of FDOM peaks, including Peak T as well as larger molecular weight compounds solely associated with allochthonous derivation. From this we have begun to understand more about the important role that the underpinning microbial community plays in the transformation, utilisation and production of FDOM. To further this research and enhance the knowledge surrounding microbially derived FDOM our recent research has focussed on the analysis of the FDOM signature of different bacterial species; Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa. To do this, we have developed a non-fluorescent media to culture individual bacteria species. By undertaking bacterial growth curves, alongside fluorescence spectroscopy, we have been able to determine FDOM development with population growth, highlighting which FDOM peaks are associated with cell multiplication and which as a metabolic by-product from other processes. We have also analysed the intracellular and extracellular fluorescence signature of each species to understand how the microbial community structure

  10. Distinguishing dissolved organic matter at its origin: size and optical properties of leaf-litter leachates.

    PubMed

    Cuss, C W; Guéguen, C

    2013-09-01

    Dissolved organic matter (DOM) was leached from eight distinct samples of leaves taken from six distinct trees (red maple, bur oak at three times of the year, two sugar maple and two white spruce trees from disparate soil types). Multiple samples were taken over 72-96h of leaching. The size and optical properties of leachates were assessed using asymmetrical flow field-flow fractionation (AF4) coupled to diode-array ultraviolet/visible absorbance and excitation-emission matrix fluorescence detectors (EEM). The fluorescence of unfractionated samples was also analyzed. EEMs were analyzed using parallel factor analysis (PARAFAC) and principal component analysis (PCA) of proportional component loadings. Both the unfractionated and AF4-fractionated leachates had distinct size and optical properties. The 95% confidence ranges for molecular weight distributions were determined as: 210-440Da for spruce, 540-920Da for sugar maple, 630-800Da for spring oak leaves, 930-950Da for senescent oak, 1490-1670 for senescent red maple, and 3430-4270Da for oak leaves that were collected from the ground after spring thaw. In most cases the fluorescence properties of leachates were different for individuals from different soil types and across seasons; however, PCA of PARAFAC loadings revealed that the observed distinctiveness was chiefly species-based. Strong correlations were found between the molecular weight distribution of both unfractionated and fractionated leachates and their principal component loadings (R(2)=0.85 and 0.95, respectively). It is concluded that results support a species-based origin for differences in optical properties. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Origin of organic matter in early solar system. V - Further studies of meteoritic hydrocarbons and a discussion of their origin.

    NASA Technical Reports Server (NTRS)

    Studier, M. H.; Hayatsu, R.; Anders, E.

    1972-01-01

    The Murchison meteorite contains aliphatic and aromatic hydrocarbons similar to those made in static Fischer-Tropsch-type syntheses. Principal compound classes above C8 are n-alkanes, mono- and dimethylalkanes, alkenes, alkylbenzenes and -naphthalenes. Below C8, n-alkanes are virtually absent; instead, benzene, toluene, branched alkanes dominate. The CH4/C2H6 ratio is greater than 30, possibly greater than 700. Isoprenoids from C17 to C20 occur in a surface rinse but not in subsequent extracts and appear to be terrestrial contaminants. Thiophenes, porphyrin-like pigments, and chlorobenzenes were also found; the latter appear to be contaminants. In the Allende meteorite, only methane, benzene, toluene and an aromatic polymer seem to be indigeneous. A comprehensive review of current evidence shows that Fischer-Tropsch-type reactions can account for most principal features of meteorite organic matter.

  12. Origin of organic matter in early solar system. V - Further studies of meteoritic hydrocarbons and a discussion of their origin.

    NASA Technical Reports Server (NTRS)

    Studier, M. H.; Hayatsu, R.; Anders, E.

    1972-01-01

    The Murchison meteorite contains aliphatic and aromatic hydrocarbons similar to those made in static Fischer-Tropsch-type syntheses. Principal compound classes above C8 are n-alkanes, mono- and dimethylalkanes, alkenes, alkylbenzenes and -naphthalenes. Below C8, n-alkanes are virtually absent; instead, benzene, toluene, branched alkanes dominate. The CH4/C2H6 ratio is greater than 30, possibly greater than 700. Isoprenoids from C17 to C20 occur in a surface rinse but not in subsequent extracts and appear to be terrestrial contaminants. Thiophenes, porphyrin-like pigments, and chlorobenzenes were also found; the latter appear to be contaminants. In the Allende meteorite, only methane, benzene, toluene and an aromatic polymer seem to be indigeneous. A comprehensive review of current evidence shows that Fischer-Tropsch-type reactions can account for most principal features of meteorite organic matter.

  13. The compositional classification of chondrites. V - The Karoonda (CK) group of carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Kallemeyn, G. W.; Rubin, A. E.; Wasson, J. T.

    1991-03-01

    In the Karoonda, or 'CK' group of carbonaceous chondrites, all normal members are metamorphosed and, while some contain shock veins, all exhibit various degrees of blackening due to fine sulfide and magnetite particle dispersions in silicates. The elemental abundance patterns in CK chondrites are similar to those in CO chondrites, and rather more similar to those in CV chondrites; CK refractory siderophile abundances are intermediate between CV and CO levels. The exceptional abundance of CK chondrites in Antarctica is accounted for in light of the fragmentation of the CK parent objects, which produced a greater proportion of small micrometeoroids.

  14. Space Weathering of Ordinary Chondrite Parent Bodies, Its Impact on the Method of Distinguishing H, L, and LL Types and Implications for Itokawa Samples Returned by the Hayabusa Mission

    NASA Technical Reports Server (NTRS)

    Hiroi, T.; Sasaki, S.; Noble, S. K.; Pieters, C. M.

    2011-01-01

    As the most abundance meteorites in our collections, ordinary chondrites potentially have very important implications on the origin and formation of our Solar System. In order to map the distribution of ordinary chondrite-like asteroids through remote sensing, the space weathering effects of ordinary chondrite parent bodies must be addressed through experiments and modeling. Of particular importance is the impact on distinguishing different types (H/L/LL) of ordinary chondrites. In addition, samples of asteroid Itokawa returned by the Hayabusa spacecraft may re veal the mechanism of space weathering on an LLchondrite parent body. Results of space weathering simulations on ordinary chondrites and implications for Itokawa samples are presented here.

  15. Distinct Purine Distribution in Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Callahan, Michael P.; Smith, Karen E.; Cleaves, Henderson J.; Ruzicka, Josef; Stern, Jennifer C.; Glavin, Daniel P.; House, Christopher H.; Dworkin, Jason P.

    2011-01-01

    Carbonaceous chondrite meteorites are known to contain a diverse suite of organic compounds, many of which are essential components of biochemistry. Amino acids, which are the monomers of proteins, have been extensively studied in such meteorites (e.g. Botta and Bada 2002; Pizzarello et aI., 2006). The origin of amino acids in meteorites has been firmly established as extraterrestrial based on their detection typically as racemic mixtures of amino acids, the presence of many non-protein amino acids, and non-terrestrial values for compound-specific deuterium, carbon, and nitrogen isotopic measurements. In contrast to amino acids, nucleobases in meteorites have been far less studied. Nucleobases are substituted one-ring (pyrimidine) or two-ring (purine) nitrogen heterocyclic compounds and serve as the information carriers of nucleic acids and in numerous coenzymes. All of the purines (adenine, guanine, hypoxanthine, and xanthine) and pyrimidines (uracil) previously reported in meteorites are biologically common and could be interpreted as the result of terrestrial contamination (e.g. van del' Velden and Schwartz, 1974.) Unlike other meteoritic organics, there have been no observations of stochastic molecular diversity of purines and pyrimidines in meteorites, which has been a criterion for establishing extraterrestrial origin. Maltins et al. (2008) performed compound-specific stable carbon isotope measurements for uracil and xanthine in the Murchison meteorite. They assigned a non-terrestrial origin for these nucleobases; however, the possibility that interfering indigenous molecules (e.g. carboxylic acids) contributed to the 13C-enriched isotope values for these nucleobases cannot be completely ruled out. Thus, the origin of these meteoritic nucleobases has never been established unequivocally. Here we report on our investigation of extracts of II different carbonaceous chondrites covering various petrographic types (Cl, CM, and CR) and degrees of aqueous alteration

  16. Comparing Amino Acid Abundances and Distributions Across Carbonaceous Chondrite Groups

    NASA Technical Reports Server (NTRS)

    Burton, Aaron S.; Callahan, Michael P.; Glavin, Daniel P.; Elsila, Jamie E.; Dworkin, Jason P.

    2012-01-01

    Meteorites are grouped according to bulk properties such as chemical composition and mineralogy. These parameters can vary significantly among the different carbonaceous chondrite groups (CI, CM, CO, CR, CH, CB, CV and CK). We have determined the amino acid abundances of more than 30 primary amino acids in meteorites from each of the eight groups, revealing several interesting trends. There are noticeable differences in the structural diversity and overall abundances of amino acids between meteorites from the different chondrite groups. Because meteorites may have been an important source of amino acids to the prebiotic Earth and these organic compounds are essential for life as we know it, the observed variations of these molecules may have been important for the origins of life.

  17. Nuclear track records in the Abee enstatite chondrite

    NASA Technical Reports Server (NTRS)

    Goswami, J. N.

    1983-01-01

    A determination of preatmospheric mass and a delineation of cosmic ray exposure history are made, through the study of nuclear track records in 14 samples taken from different locations of an Abee enstatite chondrite cut slab. Measured track densities in different samples range from 10,000 to 1,000,000/sq cm. Excess tracks of fissiogenic origin were found near the grain edges and across cleavage planes in eight enstatite grains out of the 300 analyzed. The track data rule out preirradiation of any of the analyzed samples with shielding of less than a few tens of cm. The isotrack density contours on the plane of the slab imply an asymmetric ablation of the Abee chondrite during its atmospheric transit. A sphere of about 30 cm radius approximates the preatmospheric shape and size of the Abee meteorite, which underwent a 70% mass loss during ablation.

  18. Carbonaceous chondrites as bioengineered comets

    NASA Astrophysics Data System (ADS)

    Sheldon, Robert B.; Hoover, Richard

    2012-10-01

    The discovery of microfossils on carbonaceous meteorites has electrified the public with the first concrete evidence of extraterrestrial biology. But how these organisms colonized and grew on the parent body-the comet-remains a mystery. We report on several features of cyanobacteria that permit them to bioengineer comets, as well as a tantalizing look at interplanetary uses for magnetite framboids that are found in abundance on carbonaceous chondrites. We argue that these structures provide important directionality and energy harvesting features similar to magnetotactic bacteria found on Earth.

  19. Carbonaceous Chondrite Thin Section Preparation

    NASA Technical Reports Server (NTRS)

    Harrington, R.; Righter, K.

    2017-01-01

    Carbonaceous chondrite meteorites have long posed a challenge for thin section makers. The variability in sample hardness among the different types, and sometimes within individual sections, creates the need for an adaptable approach at each step of the thin section making process. This poster will share some of the procedural adjustments that have proven to be successful at the NASA JSC Meteorite Thin Section Laboratory. These adjustments are modifications of preparation methods that have been in use for decades and therefore do not require investment in new technology or materials.

  20. (40)Ar/(39)Ar Age of Hornblende-Bearing R Chondrite LAP 04840

    NASA Technical Reports Server (NTRS)

    Righter, K.; Cosca, M.

    2015-01-01

    Chondrites have a complex chronology due to several variables affecting and operating on chondritic parent bodies such as radiogenic heating, pressure and temperature variation with depth, aqueous alteration, and shock or impact heating. Unbrecciated chondrites can record ages from 4.56 to 4.4 Ga that represent cooling in small parent bodies. Some brecciated chondrites exhibit younger ages (much less than 4 to 4.4 Ga) that may reflect the age of brecciation, disturbance, or shock and impact events (much less than 4 Ga). A unique R chondrite was recently found in the LaPaz Icefield of Antarctica - LAP 04840. This chondrite contains approximately 15% hornblende and trace amounts of biotite, making it the first of its kind. Studies have revealed an equigranular texture, mineral equilibria yielding equilibration near 650-700 C and 250-500 bars, hornblende that is dominantly OH-bearing (very little Cl or F), and high D/H ratios. To help gain a better understanding of the origin of this unique sample, we have measured the (40)Ar/(39)Ar age (LAP 04840 split 39).

  1. Partial melting of ordinary chondrites: Lost City (H) and St. Severin (LL)

    NASA Technical Reports Server (NTRS)

    Jurewicz, Amy J. G.; Jones, John H.; Weber, Egon T.; Mittlefehldt, David W.

    1993-01-01

    Eucrites and diogenites are examples of asteroidal basalts and orthopyroxenites, respectively. As they are found intermingled in howardites, which are inferred to be regolith breccias, eucrites and diogenites are thought to be genetically related. But the details of this relationship and of their individual origins remain controversial. Work by Jurewicz et al. showed that 1170-1180 C partial melts of the (anhydrous) Murchison (CM) chondrite have major element compositions extremely similar to primitive eucrites, such as Sioux County. However, the MnO contents of these melts were about half that of Sioux County, a problem for the simple partial melting model. In addition, partial melting of Murchison could not produce diogenites, because residual pyroxenes in the Murchison experiments were too Fe- and Ca-rich and were minor phases at all but the lowest temperatures. A parent magma for diogenites needs an expanded low-calcium pyroxene field. In their partial melting study of an L6 chondrite, Kushiro and Mysen found that ordinary chondrites did have an expanded low-Ca pyroxene field over that of CV chondrites (i.e., Allende), probably because ordinary chondrites have lower Mg/Si ratios. This study expands that of both Kushiro and Mysen and Jurewicz et al. to the Lost City (H) and St. Severin (LL) chondrites at temperatures ranging from 1170 to 1325 C, at an fO2 of one log unit below the iron-wuestite buffer (IW-1).

  2. The amino acid and hydrocarbon contents of the Paris meteorite, the most primitive CM chondrite

    NASA Astrophysics Data System (ADS)

    Martins, Zita; Modica, Paola; Zanda, Brigitte; Le Sergeant d'Hendecourt, Louis

    2015-04-01

    The Paris meteorite is reported to be the least aqueously altered CM chondrite [1,2], and to have experienced only weak thermal metamorphism [2-5]. The IR spectra of some of Paris' fragments suggest a primitive origin for the organic matter in this meteorite, similar to the spectra from solid-state materials in molecular clouds [6]. Most of the micron-sized organic particles present in the Paris matrix exhibit 0 < δD <2000‰ [7,8]. In order to understand the effect of aqueous alteration and thermal metamorphism on the abundance and distribution of meteoritic soluble organic matter, we have analyzed for the first time the amino acid and hydrocarbon contents of the Paris meteorite [9]. Extensive aqueous alteration in the parent body of carbonaceous meteorites may result in the decomposition of α-amino acids and the synthesis of β- and γ-amino acids. When plotted with several CM chondrites, Paris has the lowest relative abundance of β-alanine/glycine (0.15) for a CM chondrite, which fits with the relative abundance of β-alanine/glycine increasing with increasing aqueous alteration [10,11]. In addition, our results show that the isovaline detected in this meteorite is racemic (D/L= 0.99 ± 0.08; L-enantiomer excess (%) = 0.35 ± 0.5; corrected D/L = 1.03; corrected L-enantiomer excess (%) = -1.4 ± 2.6). Although aqueous alteration does not create by itself an isovaline asymmetry, it may amplify a small enantiomeric excess. Therefore, our data may support the hypothesis that aqueous alteration is responsible for the high L-enantiomer excess of isovaline observed in the most aqueously altered carbonaceous meteorites [12,13]. Paris has n-alkanes ranging from C16 to C25 and 3- to 5-ring non-alkylated polycyclic aromatic hydrocarbons (PAHs). The lack of alkylated PAHs in Paris seems to be related to the low degree of aqueous alteration on its parent body [9,14]. The extra-terrestrial aliphatic and aromatic hydrocarbon content of Paris may have an interstellar origin

  3. The Oxidation (Not Reduction) of Ordinary Chondrites During Metamorphism

    NASA Astrophysics Data System (ADS)

    McSween, H. Y., Jr.; Labotka, T. C.

    1992-07-01

    Subtle but systematic changes in the compositions and relative abundances of olivine, pyroxene, and metal with increasing petrologic type in equilibrated (types 4-6) H, L, and LL chondrites suggest that metallic Fe in these meteorites was oxidized during metamorphism. Observed changes include increases in the mean Fe contents of olivine and pyroxene and in the mean Ni and Co contents of bulk metal, as well as increases in the olivine:low-Ca pyroxene ratio with decreasing metal abundance. This evidence for oxidation is at variance with the commonly accepted idea that chondritic Fe was reduced by graphite during metamorphism (Ringwood, 1965; Williams, 1971; Brett and Sato, 1984; Rubin et al., 1988). We suggest that graphite activity was lowered by its dissolution in taenite at metamorphic temperatures, so that redox state was determined largely by equilibrium between ferromagnesian silicates and metal. Oxygen fugacities calculated from chondrite mineral equilibria are 2-3 log units below intrinsic fO(sub)2 measurements (Brett and Sato, 1984). The mineralogies of type 3 chondrites do not conform to the oxidation sequence seen in types 4-6 chondrites, and there is some evidence to suggest that Fe in unequilibrated chondrites was actually reduced during mild heating. Apparently, redox conditions in the surficial layers of parent bodies were reducing, but were oxidizing in the hotter interiors. Much of the current confusion over oxidation versus reduction is attributable to comparing unequilibrated and equilibrated chondrites. Progressive oxidation of Fe during metamorphism implies reaction with an oxidizing agent no longer present in the meteorites. We suggest that this oxidant was an aqueous vapor, derived from heating small amounts of ices originally accreted into the parent asteroids. The condensation of this vapor in cooler, outer layers of asteroids could account for aqueous alteration phases documented in some type 3 chondrites (Alexander et al., 1989). Assuming

  4. Chondritic xenon in the Earth's mantle.

    PubMed

    Caracausi, Antonio; Avice, Guillaume; Burnard, Peter G; Füri, Evelyn; Marty, Bernard

    2016-05-05

    Noble gas isotopes are powerful tracers of the origins of planetary volatiles, and the accretion and evolution of the Earth. The compositions of magmatic gases provide insights into the evolution of the Earth's mantle and atmosphere. Despite recent analytical progress in the study of planetary materials and mantle-derived gases, the possible dual origin of the planetary gases in the mantle and the atmosphere remains unconstrained. Evidence relating to the relationship between the volatiles within our planet and the potential cosmochemical end-members is scarce. Here we show, using high-precision analysis of magmatic gas from the Eifel volcanic area (in Germany), that the light xenon isotopes identify a chondritic primordial component that differs from the precursor of atmospheric xenon. This is consistent with an asteroidal origin for the volatiles in the Earth's mantle, and indicates that the volatiles in the atmosphere and mantle originated from distinct cosmochemical sources. Furthermore, our data are consistent with the origin of Eifel magmatism being a deep mantle plume. The corresponding mantle source has been isolated from the convective mantle since about 4.45 billion years ago, in agreement with models that predict the early isolation of mantle domains. Xenon isotope systematics support a clear distinction between mid-ocean-ridge and continental or oceanic plume sources, with chemical heterogeneities dating back to the Earth's accretion. The deep reservoir now sampled by the Eifel gas had a lower volatile/refractory (iodine/plutonium) composition than the shallower mantle sampled by mid-ocean-ridge volcanism, highlighting the increasing contribution of volatile-rich material during the first tens of millions of years of terrestrial accretion.

  5. Electrical conductivity of chondritic meteorites

    NASA Technical Reports Server (NTRS)

    Duba, AL; Didwall, E. M.; Burke, G. J.; Sonett, C. P.

    1987-01-01

    The electrical conductivity of samples of the Murchison and Allende carbonaceous chondrites is 4 to 6 orders of magnitude greater than rock forming minerals such as olivine for temperatures up to 700 C. The remarkably high electrical conductivity of these meteorites is attributed to carbon at the grain boundaries. Much of this carbon is produced by pyrolyzation of hydrocarbons at temperatures in excess of 150 C. As the temperature increases, light hydrocarbons are driven off and a carbon-rich residue or char migrates to the grain boundaries enhancing electrical conductivity. Assuming that carbon was present at the grain boundaries in the material which comprised the meteorite parent bodies, the electrical heating of such bodies was calculated as a function of body size and solar distance during a hypothetical T-Tauri phase of the sun. Input conductivity data for the meteorite parent body were the present carbonaceous chondrite values for temperatures up to 840 C and the electrical conductivity values for olivine above 840 C.

  6. Thermal recalcitrance of the organic D-rich component of ordinary chondrites

    NASA Astrophysics Data System (ADS)

    Remusat, L.; Piani, L.; Bernard, S.

    2016-02-01

    Carbonaceous and ordinary chondrites (CCs and OCs) contain insoluble organic matter (IOM) with large D-excess compared to other objects in the solar system. The higher the temperature experienced by CCs, the lower the D/H ratio of their IOM. It seems to be the opposite for OCs. Here, we report NanoSIMS H- (and N-) isotopic imaging of IOM of three OCs that experienced thermal metamorphism in the sequence Semarkona, Bishunpur and GRO 95502. In addition, we performed flash heating experiments on the IOM of GRO 95502 at 600 °C and characterized the residues using NanoSIMS, Raman and XANES spectroscopy. The present study shows that, in contrast to IOM of CI, CM and CR, IOM of OCs exhibits very few D-rich (or 15N-rich) hotspots. Furthermore, although the evolution of the molecular structure of OC and CC IOM is similar upon heating, their D/H ratios do not follow the same trend: the D/H of OC IOM drastically increases while the D/H of CC IOM decreases. In contrast to CC IOM, the D-rich component of which does not survive at high temperatures, the present results highlight the thermal recalcitrance of the D-rich component of OC IOM. This suggests that CCs and OCs did not accrete the same organic material, thereby challenging the hypothesis of a common precursor on chondritic parent bodies. The present results support the hypothesis that OC IOM contains an organic component that could originate from the interstellar medium.

  7. Noble Gases in the LEW 88663 L7 Chondrite

    NASA Astrophysics Data System (ADS)

    Miura, Y. N.; Sugiura, N.; Nagao, K.

    1995-09-01

    likely terrestrial contamination in origin) rather than chondritic ones seem to be dominant in LEW88663. A K-Ar age of 4.3 +/- 0.2 b.y. is obtained assuming K content of 660 ppm by [9], implying radiogenic ^40Ar is almost retained. Because of low abundance of trapped Xe in the meteorite compared with the abundances in other chondrites, ^244Pu-derived fission Xe could be evaluated more precisely. According to the measured Xe data (for this, three isotope plots such as ^134Xe/^130Xe versus ^136Xe/^130Xe are useful), we conclude that Xe in LEW88663 is the mixture of ^244Pu-derived fission Xe and the terrestrial atmospheric Xe with possibility that a small amount of chondritic Xe is contained. Using the same procedure described in [10], we obtained excess ^136Xe concentration, 1.4 x 10^-12 cm^3STP/g with about 20% uncertainty, of which about 3% is from contribution of ^238U-derived ^136Xe if average U content for L chondrite (14 ppb) is assumed. The calculated Pu abundance of 0.21 ppb is slightly higher than those reported for L chondrites Barwell (0.11 +/- 0.05 ppb [11]) and Marion (0.10+/-0.40 ppb [11]). Acknowledgments: We thank Meteorite Working Group for providing the sample. We are also grateful to Dr. D. Mittlefehldt for showing us his chemical composition data. This work is supported by Research Fellowships of the Japan Society for the Promotion of Science for Young Scientists. References: [1] Mason B. et al. (1992) Antarc. Meteorite Newsletter, 15(2), 30. [2] Mason B. and Marlow R. (1992) Antarc. Meteorite Newsletter, 15(1), 16. [3] Davis A. M. et al. (1993) LPS XXIV, 375-376. [4] Mittlefehldt D. W. (1993) Meteoritics, 28, 401-402. [5] Hervey R. P. (1993) Meteoritics, 28, 360. [6] Eugster O. (1988) GCA, 52, 1649-1662. [7] Marti K. and Graf T.(1992) Annu. Rev. Earth Planet Sci., 20, 221-243. [8] E.g. Marti K. (1967) EPSL, 2, 193-196. [9] Mittlefehldt D. W., personal communication. [10] Miura Y. et al. (1993) GCA, 57, 1857-1866. [11] Hagee B. et al. (1990) GCA, 54

  8. Preservation of ancient impact ages on the R chondrite parent body: 40Ar/39Ar age of hornblende-bearing R chondrite LAP 04840

    USGS Publications Warehouse

    Righter, Kevin; Cosca, Michael A.; Morgan, Leah

    2016-01-01

    The hornblende- and biotite-bearing R chondrite LAP 04840 is a rare kind of meteorite possibly containing outer solar system water stored during metamorphism or postshock annealing deep within an asteroid. Because little is known regarding its age and origin, we determined 40Ar/39Ar ages on hornblende-rich separates of the meteorite, and obtained plateau ages of 4340(±40) to 4380(±30) Ma. These well-defined plateau ages, coupled with evidence for postshock annealing, indicate this meteorite records an ancient shock event and subsequent annealing. The age of 4340–4380 Ma (or 4.34–4.38 Ga) for this and other previously dated R chondrites is much older than most impact events recorded by ordinary chondrites and points to an ancient event or events that predated the late heavy bombardment that is recorded in so many meteorites and lunar samples.

  9. Formation timescales of CV chondrites from component specific Hf-W systematics

    NASA Astrophysics Data System (ADS)

    Becker, Maike; Hezel, Dominik C.; Schulz, Toni; Elfers, Bo-Magnus; Münker, Carsten

    2015-12-01

    Carbonaceous chondrites are an important meteorite group that closely resembles the bulk composition of the solar system. We report the first elemental and isotope dataset for Hf-W in carbonaceous chondrites that includes chondrules, matrix, magnetic fractions as well as bulk compositions. Our study focuses on the three CV3 chondrites, Allende, Vigarano and Bali. Compared to bulk chondrites, matrix splits have low Hf/W ratios and ε182W compositions, whereas chondrule splits are characterized by high, but more variable, Hf/W ratios and ε182W compositions. Thus, Hf/W ratios behave complementary between chondrules and matrix in the analysed CV chondrites, supporting the view that both components formed from the same parental reservoir. Strong nucleosynthetic effects were observed in most of the analysed CV3 components, especially in matrices and chondrule splits that were found to have large ε183W anomalies of several ε-units. All separates define a rough correlation between initial 182W/184W and 183W/184W ratios, in agreement with theoretical model trends based on calculations for stellar nucleosynthesis. Our results, therefore, indicate a heterogeneous distribution of s- and r-process W isotopes among the different CV3 chondrite components, arguing for selective thermal processing of early solar system matter during chondrule formation. After correcting for nucleosynthetic anomalies, chondrules and matrix splits of reduced (Vigarano) as well as oxidised (Allende) CV3 chondrites define a linear correlation in ε182W vs. 180Hf/184W space, which is interpreted as an isochron, covering an age interval within the first ∼2.6 Ma after solar system formation. As peak metamorphic temperatures for CV3 chondrites were well below the 182Hf-182W closure temperature, the resulting isochron within its error most likely defines a common formation interval for all components. The calculated age interval is for the first time based on a combined chondrule-matrix isochron, a

  10. Bleached chondrules: Evidence for widespread aqueous processes on the parent asteroids of ordinary chondrites

    NASA Astrophysics Data System (ADS)

    Grossman, Jeffrey N.; Alexander, Conel M. O'd.; Wang, Jianhua; Brearley, Adrian J.

    2000-05-01

    degree of aqueous alteration is consistent with the source of water being either accreted ices or water released during oxidation of organic matter. Ordinary chondrites were probably open systems after accretion, and aqueous fluids may have carried volatile elements with them during dehydration. Individual radial pyroxene and cryptocrystalline chondrules were certainly open systems in all chondrites that experienced aqueous alteration leading to bleaching.

  11. Bleached chondrules: Evidence for widespread aqueous processes on the parent asteroids of ordinary chondrites

    USGS Publications Warehouse

    Grossman, J.N.; Alexander, C.M. O'D.; Wang, Jingyuan; Brearley, A.J.

    2000-01-01

    aqueous alteration is consistent with the source of water being either accreted ices or water released during oxidation of organic matter. Ordinary chondrites were probably open systems after accretion, and aqueous fluids may have carried volatile elements with them during dehydration. Individual radial pyroxene and cryptocrystalline chondrules were certainly open systems in all chondrites that experienced aqueous alteration leading to bleaching.

  12. Origin of particulate organic matter exported during storm events in a forested headwater catchment.

    NASA Astrophysics Data System (ADS)

    Jeanneau, Laurent; Rowland, Richard D.; Inamdar, Shreeram P.

    2016-04-01

    Particulate organic matter (POM) plays an important biogeochemical role towards ecology, ecotoxicology and carbon cycle. Moreover POM within the fluvial suspended sediment load during infrequent high flows can comprise a larger portion of long-term flux than dissolved species. It is well documented that storm events that constituted only 10-20% of the year contributed to >80% of POC exports. But the origin and composition of POM transferred during those hot moments remained unclear. In order to improve our knowledge on this topic we explore the variability in storm event-transported sediments' POM content and source down a continuum of catchment drainage locations. Wetland, upland and forest O horizons, litter, river banks and bed sediments were analyzed for their content in organic C, isotopic (13C) and molecular (thermochemiolysis-gas chromatography-mass spectrometry) fingerprints. The isotopic and molecular fingerprints recorded in suspended and deposited (differentiated into fine, medium and coarse particles) sediments sampled during different storm events down a continuum of catchment drainage locations (12 and 79 ha). This study highlights compositional differences between the catchment size (12 versus 79 ha), the particle size of deposited sediment (fine versus medium versus coarse) and the sampling time during a storm event (rising limb versus peak flow versus falling limb). Two sampling strategies were used. Suspended sediments sampled at a specific time during flood events allow evaluating changes along the hydrograph, while deposited sediments that integrate the entire event allow making comparisons with drainage scale. For deposited sediments, the proportion of OM coming from the endmembers wetland, litter and Forest O horizon decreases from the 12ha to the 79ha catchment, which exhibited a higher proportion of OM coming from stream bed sediment and river banks. For both catchments, from fine to coarse particles, the influence of stream bed sediments

  13. A Raman Study of Carbonates and Organic Contents in Five CM Chondrites

    NASA Technical Reports Server (NTRS)

    Chan, Q. H. S.; Zolensky, M. E.; Bodnar, R. J.; Farley, C.; Cheung, J. C. H.

    2016-01-01

    Carbonates comprise the second most abundant class of carbon-bearing phases in carbonaceous chondrites after organic matter (approximately 2 wt.%), followed by other C-bearing phases such as diamond, silicon carbide, and graphite. Therefore, understanding the abundances of carbonates and the associated organic matter provide critical insight into the genesis of major carbonaceous components in chondritic materials. Carbonates in CM chondrites mostly occur as calcite (of varying composition) and dolomite. Properly performed, Raman spectroscopy provides a non-destructive technique for characterizing meteorite mineralogy and organic chemistry. It is sensitive to many carbonaceous phases, allows the differentiation of organic from inorganic materials, and the interpretation of their spatial distribution. Here, with the use of Raman spectroscopy, we determine the structure of the insoluble organic matter (IOM) in the matrix and carbonate phases in five CM chondrites: Jbilet Winselwan, Murchison, Nogoya, Santa Cruz, and Wisconsin Range (WIS) 91600, and interpret the relative timing of carbonate precipitation and the extent of the associated alteration events.

  14. In situ observation of D-rich carbonaceous globules embedded in NWA 801 CR2 chondrite

    NASA Astrophysics Data System (ADS)

    Hashiguchi, Minako; Kobayashi, Sachio; Yurimoto, Hisayoshi

    2013-12-01

    Eighty-five D-rich carbonaceous particles were identified in the matrix of the NWA 801 CR2 chondrite using isotope microscopy. The occurrence of 67 D-rich carbonaceous particles was characterized using secondary electron microscopy combined with X-ray elemental mapping. The close association of H and C, and D-enrichment suggests that the D-rich carbonaceous particles correspond to organic matter. The D-rich organic particles were scattered ubiquitously throughout the matrix at a concentration of approximately 660 ppm. The morphology of the D-rich carbonaceous particles is globular up to about 1 μm in diameter and is classified into four types: ring globules, round globules, irregular-shaped globules, and globule aggregates. The ring globules are ring-shaped organic matter containing silicate and/or oxide, with or without a void in the center. This is the first report of silicate and oxide grains surrounded by D-rich organic matter. The globule aggregates are composed of several D-rich organic globules mixed with silicates. Morphology of ring globules is very similar to core-mantle grain produced in the molecular cloud or in the outer solar nebula inferring by astronomy, suggesting that the organic globules have formed by UV photolysis in the ice mantle. Silicates or oxides attached to D-rich organic globules are the first observation among chondrites so far and may be unique nature of CR2 chondrites. The hydrogen isotopic compositions of the ring globules, round globules, irregular-shaped globules, and globule aggregates are δD = 3000-4800, 2900-8100, 2700-11,000, and 2500-11,000‰, respectively. Variations of D/H ratio of these organic globules seemed to be attributed to variations of D/H ratio of the organic radicals or differences of content of the D-rich organic radicals. There are no significant differences in the hydrogen isotopic compositions among the four types of D-rich carbonaceous matter. The D-enrichments suggest that these organic globules have

  15. Enstatite chondrites and achondrites as asteroidal resources

    NASA Technical Reports Server (NTRS)

    Hutson, M. L.; Lewis, John S.

    1991-01-01

    The highly reduced nature of the enstatite meteorites (chondrites and achondrites) differs from that of all other types of stony meteorites. The silicates in the enstatite meteorites contain almost no FeO. In addition, many normally lithophile elements such as Na, Ca, Mg, Cr, and Ti display chalcophilic behavior. A study of the chemistry and mineralogy of the enstatite meteorites was undertaken to determine their resource potential. On average, about 99 percent of the volume of an enstatite achondrite, or aubrite, consists of only four silicate minerals: enstatite, Na-rich plagioclase, diopside, and forsterite, with enstatite being by far the most abundant mineral. The remaining one percent of the volume consists of troilite, kamacite, and trace amounts of oldhamite, daubreelite, ferromagnesian albandite, and schreibersite. Thus, the aubrites can be considered as a possible source for large quantities of Mg, Si, and O, but are of little interest as a source of anything else. The enstatite chondrites appear to be more promising candidates for resource utilization. The chondrites are generally divided into two groups: EH (high iron, fine-grained, with abundant chondrules); and EL (low iron, coarse-grained, with little or no evidence of chondrules). Metallic Ni-Fe makes up roughly 20-25 weight percent of each type of enstatite chondrite. These meteorites are also a good source of nitrogen. This is due in part to the presence of osbornite and sinoite. The latter mineral is restricted to EL chondrites, which typically have a higher bulk nitrogen content than the EH chondrites. Three valuable metals, Cr, Mn, and Ti, are concentrated in a few distinct sulfide phases in the enstatite chondrites. These sulfide phases are troilite and niningerite in EH chondrites and troilite, daubreelite, and ferroan alabandite in EL chondrites.

  16. Characterization and origin of polar dissolved organic matter from the Great Salt Lake

    USGS Publications Warehouse

    Leenheer, J.A.; Noyes, T.I.; Rostad, C.E.; Davisson, M.L.

    2004-01-01

    Polar dissolved organic matter (DOM) was isolated from a surface-water sample from the Great Salt Lake by separating it from colloidal organic matter by membrane dialysis, from less-polar DOM fractions by resin sorbents, and from inorganic salts by a combination of sodium cation exchange followed by precipitation of sodium salts by acetic acid during evaporative concentration. Polar DOM was the most abundant DOM fraction, accounting for 56% of the isolated DOM. Colloidal organic matter was 14C-age dated to be about 100% modern carbon and all of the DOM fractions were 14C-age dated to be between 94 and 95% modern carbon. Average structural models of each DOM fraction were derived that incorporated quantitative elemental and infrared, 13C-NMR, and electrospray/mass spectrometric data. The polar DOM model consisted of open-chain N-acetyl hydroxy carboxylic acids likely derived from N-acetyl heteropolysaccharides that constituted the colloidal organic matter. The less polar DOM fraction models consisted of aliphatic alicyclic ring structures substituted with carboxyl, hydroxyl, ether, ester, and methyl groups. These ring structures had characteristics similar to terpenoid precursors. All DOM fractions in the Great Salt Lake are derived from algae and bacteria that dominate DOM inputs in this lake.

  17. Fractionation of moderately volatile elements in ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Wasson, J. T.; Chou, C.-L.

    1974-01-01

    The CI chondrites are the most volatile-rich meteorites. Relative to the CI chondrites, the ordinary chondrites have lower abundances of refractory and volatile elements. Four types of fractionations are summarized in a table. Ordinary-chondrite/CI abundance ratios for moderately volatile elements in H- and L-group chondrites are presented in a graph. Possible explanations for the observed relations are considered, giving attention to several processes which could result in the separation of nebular solids and gases.

  18. Carbonaceous chondrite clasts in the Kapoeta howardite

    NASA Technical Reports Server (NTRS)

    Brearley, Adrian J.; Papike, J. J.

    1993-01-01

    A petrographic and mineralogical study of a number of carbonaceous chondrite clasts in the Kapoeta howardite has been carried out. Most of the clasts have mineralogical and chemical properties which link them to the CM carbonaceous chondrites. Some clasts contain chondrules which often have well-developed fine-grained rims, but many have been extensively brecciated. PCP-rich objects are common and pentlandite and pyrrhotite also occur. Calcite has also been found. The remainder of the clasts are extremely fine-grained and appear to be closely related to CI carbonaceous chondrites. In these clasts magnetite framboids are common and finegrained sulfides and magnetite occur disseminated throughout the matrix.

  19. Thermal metamorphism. [of chondrite parent bodies

    NASA Technical Reports Server (NTRS)

    Mcsween, Harry Y., Jr.; Sears, Derek W. G.; Dodd, Robert T.

    1988-01-01

    Most chondrites have experienced thermal metamorphism, resulting in changes in texture, mineralogy and possibly chemical composition. The physical conditions for metamorphism range from approximately 400 to 1000 C at low lithostatic pressure. Metamorphism may have resulted from decay of short-lived radionuclides, electromagnetic induction or accretion of hot materials. Several thermal models for chondrite parent bodies have been proposed. The least metamorphosed type-3 chondrites probably carry the most information about the early solar system, but even these have been affected to some degree by thermal processing.

  20. The compositional classification of chondrites: 5. The Karoonda (CK) group of carbonaceous chondrites

    SciTech Connect

    Kallemeyn, G.W.; Rubin, A.E.; Wasson, J.T. )

    1991-03-01

    Petrographic and bulk compositional data reveal the existence of a new group of carbonaceous chondrites consisting of the observed fall, Karoonda, one large find from Maralinga, Australia, and 6-11 small finds from five sites in Antarctica. Ningqiang, also a fall, is genetically related to the group. Compositional, textural, and O-isotope data show that the new group is closely related to CV and CO chondrites. In keeping with the practice of naming carbonaceous chondrite groups after a prominent member, the authors designate it the Karoonda or CK group. All normal CK members are metamorphosed; petrographic grades range from 4 to 6. Some contain shock veins and all exhibit various degrees of blackening due to the dispersion of fine particles of sulfides and magnetite in silicates. Only one other group (EL) has no unequilibrated members. The unequilibrated Ningqiang chondrite is more similar to CK than to CV or CO chondrites, but differs significantly in detailed composition. Elemental abundance patterns in CK chondrites are similar to those in CO chondrites, and even more similar to those in CV chondrites. It appears that nebular conditions and processes were closely similar at the CK and CV formation locations. Although precise probability calculations are difficult because of uncertainties regarding pairing and because so few samples are known, the exceptional abundance of CK chondrites in Antarctica requires an explanation.

  1. Siderophile trace elements in metals and sulfides in enstatite achondrites record planetary differentiation in an enstatite chondritic parent body

    NASA Astrophysics Data System (ADS)

    van Acken, D.; Humayun, M.; Brandon, A. D.; Peslier, A. H.

    2012-04-01

    Siderophile element concentrations were measured by LA-ICP-MS in metals and sulfides from five aubrite meteorites. Siderophile element patterns in aubrites are either similar to those in metal from enstatite chondrites, or can be derived by crystallization from metallic liquids derived by partial melting of E chondrites. Some metal grains in Mt. Egerton, Cumberland Falls, and Aubres show moderate to severe depletion in compatible highly siderophile elements (Re, Os, Ir, Ru) which are consistent with solid metal/liquid metal differentiation of enstatite chondrite-like metal. Metals from chondrite inclusions in Cumberland Falls show more extremely fractionated patterns than those from the aubritic matrix, potentially hinting at fractionation and partial melting processes affecting not only the aubrite parent body, but the chondrite body from which the inclusions were derived as well. Models using experimental partition coefficients show that aubrite metal chemically corresponds to solid metal segregated during differentiation of primary metallic liquids of EH/EL composition that contained both substantial S- and C-contents. This result is consistent with a genetic link between enstatite chondrites and aubrites, but as to whether aubrites were derived from the same body(ies) as enstatite chondrites, or have their origin in multiple, and potentially separated bodies, cannot be answered unequivocally with chemical or isotopic data alone.

  2. Hydrogen and carbon isotopic ratios of polycyclic aromatic compounds in two CM2 carbonaceous chondrites and implications for prebiotic organic synthesis

    NASA Astrophysics Data System (ADS)

    Huang, Yongsong; Aponte, José C.; Zhao, Jiaju; Tarozo, Rafael; Hallmann, Christian

    2015-09-01

    Study of meteoritic organic compounds offers a unique opportunity to understand the origins of the organic matter in the early Solar System. Meteoritic polycyclic aromatic hydrocarbons (PAHs) and heteropolycyclic aromatic compounds (HACs) have been studied for over fifty years, however; their hydrogen stable isotopic ratios (δD) have never been reported. Compound-specific δD measurements of PAHs and HACs are important, in part because the carbon isotopic ratios (δ13C) of various meteoritic PAHs cannot be readily distinguished from their terrestrial counterparts and it is difficult to rule out terrestrial contamination based on carbon isotopic ratios alone. In this study, we have extracted and identified more than sixty PAHs and HACs present in two CM2 carbonaceous chondrites Murchison and LON 94101. Their carbon and hydrogen stable isotopic ratios (δ13C and δD) were measured and used to discuss about their synthetic environments and formation mechanisms. The concentration of aromatic compounds is ∼30% higher in Murchison than in the Antarctic meteorite LON 94101, but both samples contained similar suites of PAHs and HACs. All PAHs and HACs found exhibited positive δD values (up to 1100‰) consistent with an extraterrestrial origin, indicating the relatively low δ13C values are indeed an inherent feature of the meteoritic aromatic compounds. The hydrogen isotopic data suggest aromatic compounds in carbonaceous chondrites were mainly formed in the cold interstellar environments. Molecular level variations in hydrogen and carbon isotopic values offer new insights to the formation pathways for the aromatic compounds in carbonaceous chondrites.

  3. Initial phase of transformation and redistribution of original organic matter in modern sediments under experimental conditions

    SciTech Connect

    Veber, V.V.; Telkova, M.S.

    1983-01-01

    The authors discuss the results of an experiment extending over 25 years based on the transformation in a reducing environment of the organic matter of crustaceans (Pontogammarus), taken as an example of possible representatives of oil-producing organisms. The material obtained at the end of the experiment produced bituminous components rich in hydrocarbons, which are described in detail and compared with similar extracts from oil-bearing rocks.

  4. The Effects of Parent Body Processes on Amino Acids in Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Glavin, Daniel P.; Callahan, Michael P.; Dworkin, Jason P.; Elsila, Jamie E.

    2010-01-01

    To investigate the effect of parent body processes on the abundance, distribution, and enantiomeric composition of amino acids in carbonaceous chondrites, the water extracts from nine different powdered Cl, CM, and CR carbonaceous chondrites were analyzed for amino acids by ultrahigh performance liquid chromatography-fluorescence detection and time-of-flight mass spectrometry (UPLC-FD/ToF-MS). Four aqueously altered type 1 carbonaceous chondrites including Orgueil (C11), Meteorite Hills (MET) 01070 (CM1), Scott Glacier (SCO) 06043 (CM1), and Grosvenor Mountains (GRO) 95577 (CR1) were analyzed using this technique for the first time. Analyses of these meteorites revealed low levels of two- to five-carbon acyclic amino alkanoic acids with concentrations ranging from -1 to 2,700 parts-per-billion (ppb). The type 1 carbonaceous chondrites have a distinct distribution of the five-carbon (C5) amino acids with much higher relative abundances of the gamma- and delta-amino acids compared to the type 2 and type 3 carbonaceous chondrites, which are dominated by a-amino acids. Much higher amino acid abundances were found in the CM2 chondrites Murchison, Lonewolf Nunataks (LON) 94102, and Lewis Cliffs (LEW) 90500, the CR2 Elephant Moraine (EET) 92042, and the CR3 Queen Alexandra Range (QUE) 99177. For example, a-aminoisobutyric acid ((alpha-AIB) and isovaline were approximately 100 to 1000 times more abundant in the type 2 and 3 chondrites compared to the more aqueously altered type 1 chondrites. Most of the chiral amino acids identified in these meteorites were racemic, indicating an extraterrestrial abiotic origin. However, non-racemic isovaline was observed in the aqueously altered carbonaceous chondrites Murchison, Orgueil, SCO 06043, and GRO 95577 with L-isovaline excesses ranging from approximately 11 to 19%, whereas the most pristine, unaltered carbonaceous chondrites analyzed in this study had no detectable L-isovaline excesses. These results are consistent with the

  5. The effects of parent body processes on amino acids in carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Glavin, Daniel P.; Callahan, Michael P.; Dworkin, Jason P.; Elsila, Jamie E.

    2010-12-01

    To investigate the effect of parent body processes on the abundance, distribution, and enantiomeric composition of amino acids in carbonaceous chondrites, the water extracts from nine different powdered CI, CM, and CR carbonaceous chondrites were analyzed for amino acids by ultra performance liquid chromatography-fluorescence detection and time-of-flight mass spectrometry (UPLC-FD/ToF-MS). Four aqueously altered type 1 carbonaceous chondrites including Orgueil (CI1), Meteorite Hills (MET) 01070 (CM1), Scott Glacier (SCO) 06043 (CM1), and Grosvenor Mountains (GRO) 95577 (CR1) were analyzed using this technique for the first time. Analyses of these meteorites revealed low levels of two- to five-carbon acyclic amino alkanoic acids with concentrations ranging from approximately 1 to 2,700 parts-per-billion (ppb). The type 1 carbonaceous chondrites have a distinct distribution of the five-carbon (C5) amino acids with much higher relative abundances of the γ- and δ-amino acids compared to the type 2 and type 3 carbonaceous chondrites, which are dominated by α-amino acids. Much higher amino acid abundances were found in the CM2 chondrites Murchison, Lonewolf Nunataks (LON) 94102, and Lewis Cliffs (LEW) 90500, the CR2 Elephant Moraine (EET) 92042, and the CR3 Queen Alexandra Range (QUE) 99177. For example, α-aminoisobutyric acid (α-AIB) and isovaline were approximately 100 to 1000 times more abundant in the type 2 and 3 chondrites compared to the more aqueously altered type 1 chondrites. Most of the chiral amino acids identified in these meteorites were racemic, indicating an extraterrestrial abiotic origin. However, nonracemic isovaline was observed in the aqueously altered carbonaceous chondrites Murchison, Orgueil, SCO 06043, and GRO 95577 with L-isovaline excesses ranging from approximately 11 to 19%, whereas the most pristine, unaltered carbonaceous chondrites analyzed in this study had no detectable L-isovaline excesses. These results are consistent with the

  6. Tin in a chondritic interplanetary dust particle

    SciTech Connect

    Rietmeijer, F.J.M. )

    1989-03-01

    Submicron platey Sn-rich grains are present in chondritic porous interplanetary dust particle (IDP) W7029 A and it is the second occurrence of a tin mineral in a stratospheric micrometeorite. Selected Area Electron Diffraction data for the Sn-rich grains match with Sn{sub 2}O{sub 3} and Sn{sub 3}O{sub 4}. The oxide(s) may have formed in the solar nebula when tin metal catalytically supported reduction of CO or during flash heating on atmospheric entry of the IDP. The presence of tin is consistent with enrichments for other volatile trace elements in chondritic IDPs and may signal an emerging trend toward nonchondritic volatile element abundances in chondritic IDPs. The observation confirms small-scale mineralogical heterogeneity in fine-grained chondritic porous interplanetary dust. 27 refs.

  7. Tellurium Stable Isotope Fractionation in Chondritic Meteorites

    NASA Astrophysics Data System (ADS)

    Fehr, M. A.; Hammond, S. J.; Parkinson, I. J.

    2014-09-01

    New Te double spike procedures were set up to obtain high-precision accurate Te stable isotope data. Tellurium stable isotope data for 16 chondrite falls are presented, providing evidence for significant Te stable isotope fractionation.

  8. Ordinary Chondrite Chondrules: Oxygen Isotope Variations

    NASA Astrophysics Data System (ADS)

    Metzler, K.; Pack, A.; Hezel, D. C.

    2017-02-01

    Chondrules in some H and LL chondrites show positive/negative correlations between size and oxygen isotopic composition. This indicates that they exchanged oxygen with different oxygen reservoirs and cannot stem from a common chondrule population.

  9. Tin in a chondritic interplanetary dust particle

    NASA Technical Reports Server (NTRS)

    Rietmeijer, Frans J. M.

    1989-01-01

    Submicron platey Sn-rich grains are present in chondritic porous interplanetary dust particle (IDP) W7029 A and it is the second occurrence of a tin mineral in a stratospheric micrometeorite. Selected Area Electron Diffraction data for the Sn-rich grains match with Sn2O3 and Sn3O4. The oxide(s) may have formed in the solar nebula when tin metal catalytically supported reduction of CO or during flash heating on atmospheric entry of the IDP. The presence of tin is consistent with enrichments for other volatile trace elements in chondritic IDPs and may signal an emerging trend toward nonchondritic volatile element abundances in chondritic IDPs. The observation confirms small-scale mineralogical heterogeneity in fine-grained chondritic porous interplanetary dust.

  10. Origins.

    PubMed

    Weinberg, S

    1985-10-04

    The farthest of the galaxies that can be seen through the large ground-based telescopes of modern astronomy, such as those on La Palma in the Canary Islands, are so far away that they appear as they did close to the time of the origin of the universe, perhaps some 10 billion years ago. Much has been learned, and much has still to be learned, about the young universe from optical and radio telescopes, but these instruments cannot be used to look directly at the universe in its first few hundred thousand years. Instead, they are used to search the relatively recent past for relics of much earlier times. Together with experiments planned for the next generation of elementary particle accelerators, astronomical observations should continue to extend what is known about the universe backward in time to the Big Bang and may eventually help to reveal the origins of the physical laws that govern the universe.

  11. Highly Pristine Organic Matter in a Xenolith Clast in the Zag H Chrondrite

    NASA Technical Reports Server (NTRS)

    Kebukawa, Y.; Ito, M.; Zolensky, M. E.; Nakato, A.; Suga, H.; Takahashi, Y.; Takeichi, Y.; Mase, K.; Chan, Q.; Fries, M.; Kobayashi, K.

    2017-01-01

    The Zag meteorite is a halite-bearing H3-6 chondrite [1]. We have been studying a dark Zag clast with abundant organic matter [2,3], which was proposed to be from Ceres [4,5]. Therefore, our systematic research of the Zag clast may provide an important linkage to the recent remote sensing observations obtained by the DAWN mission to Ceres. We prepared a new sub-sample of this clast for coordinated organic analysis by STXM-XANES and NanoSIMS, in order to understand the nature and origin of the organic matter.

  12. Petrology and geochemistry of Patuxent Range 91501, a clast-poor impact-melt from the L chondrite parent body, and Lewis Cliff 88663, an L7 chondrite

    NASA Astrophysics Data System (ADS)

    Mittlefehldt, David W.; Lindstrom, Marilyn M.

    2001-03-01

    We have performed petrologic and geochemical studies of Patuxent Range 91501 and Lewis Cliff 88663. PAT 91501, originally classified as an L7 chondrite, is rather a unique, near total impact-melt from the L chondrite parent body. Lewis Cliff 88663 was originally classified as an "achondrite (?)," but we find that it is a very weakly shocked L7 chondrite. PAT 91501 is an unshocked, homogeneous, igneous-textured ultramafic rock composed of euhedral to subhedral olivine, low-Ca pyroxene, augite and chrome-rich spinels with interstitial albitic plagioclase and minor silica-alumina-alkali-rich glass. Only ~10% relict chondritic material is present. Olivine grains are homogeneous (Fa25.2-26.8). Low-Ca pyroxene (Wo1.9-7.2En71.9-78.2Fs19.9-20.9) and augite (Wo29.8-39.0En49.2-55.3Fs11.8-14.9) display a strong linear TiO2-Al2O3 correlations resulting from igneous fractionation. Plagioclase is variable in composition; Or3.0-7.7Ab79.8-84.1An8.2-17.2. Chrome-rich spinels are variable in composition and zoned from Cr-rich cores to Ti-Al-rich rims. Some have evolved compositions with up to 7.9 wt% TiO2. PAT 91501 bulk silicate has an L chondrite lithophile element composition except for depletions in Zn and Br. Siderophile and chalcophile elements are highly depleted due to sequestration in cm-size metal-troilite nodules. The minerals in LEW 88663 are more uniform in composition than those in PAT 91501. Olivine grains have low CaO and Cr2O3 contents similar to those in L5-6 chondrites. Pyroxenes have high TiO2 contents with only a diffuse TiO2-Al2O3 correlations. Low-Ca pyroxenes are less calcic (Wo1.6-3.1En76.5-77.0Fs20.4-21.4), while augites (Wo39.5-45.6En46.8-51.1Fs7.6-9.4) and plagioclases (Or2.6-5.7Ab74.1-83.1An11.2-23.3) are more calcic. Spinels are homogeneous and compositionally similar to those in L6 chondrites. LEW 88663 has an L chondrite bulk composition for lithophile elements, and only slight depletions in siderophile and chalcophile elements that are plausibly due

  13. Amoeboid olivine aggregates from CH carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Krot, Alexander N.; Park, Changkun; Nagashima, Kazuhide

    2014-08-01

    hibonite in CAIs within AOAs reflects heterogeneous distribution of 26Al in the solar nebula during this epoch. The observed variations of the inferred initial 26Al/27Al ratios in anorthite of the mineralogically pristine and uniformly 16O-rich CH AOAs could have recorded (i) admixing of 26Al in the protoplanetary disk during the earliest stages of its evolution and/or (ii) closed-system Mg-isotope exchange between anorthite and Mg-rich minerals (spinel, forsterite, and Al-diopside) during subsequent prolonged (days-to-weeks) thermal annealing at high temperature (∼1100 °C) and slow cooling rates (∼0.01 K h-1) that has not affected their O-isotope systematics. The proposed thermal annealing may have occurred in an impact-generated plume invoked for the origin of non-porphyritic magnesian chondrules and Fe,Ni-metal grains in CH and CB carbonaceous chondrites about 5 Myr after formation of CV CAIs.

  14. Substantial Variations of Refractory Siderophile Element Ratios in Components of Unequilibrated Chondrites - Implications for Terrestrial Planet Compositions

    NASA Astrophysics Data System (ADS)

    Becker, H.; Kadlag, Y.

    2015-12-01

    Abundance ratios of refractory elements in bulk compositions of chondritic meteorites show limited variability relative to CI chondrites, typically < 10%. Whether or not this was also the case for the building materials of the terrestrial planets remains an important open question with implications for planetary chemistry and chronology (e.g. the Sm/Nd ratio of the terrestrial planets). The limited variation of these elements in chondrites has been explained by complete condensation of these elements from solar gas into oxides, silicates and metal. However, small systematic differences in abundances and ratios of specific refractory elements in different groups of chondrites suggest variable mixing ratios of refractory components in different compartments of the solar nebula. The systematic fractionations of Re/Os, Y/Ho (and other REE) between different classes of chondrites, the presence of strongly fractionated refractory metal nuggets in some carbonaceous chondrites and stable isotope variations of nucleosynthetic origin (Ru, Mo, Ti, Cr) in the bulk rocks and in leachates of chondrites suggest that the origin of refractory element fractionations in chondrites is more complicated than assumed in early models. Abundance ratios of refractory siderophile elements in physically separated components of unequilibrated chondrites show that components of the least equilibrated chondrites (petrologic type 2 to 3.4) display larger variations than bulk rocks (e.g., Pt/Ir, Rh/Ir, Ru/Ir, Re/Os vary by 20-30% or more). These data and the isotopic variations are difficult to ascribe to parent body processes or metal-sulfide-silicate partitioning during chondrule formation. Rather the different end members appear to preserve differences inherited from fractional condensation or evaporation of dust precursors of chondrules, matrix and Fe-Ni metal that were later efficiently mixed in nebular compartments to yield approximately CI chondrite like ratios of refractory elements

  15. Validity of trace element cosmothermometer. [for accretion range of chondrites

    NASA Technical Reports Server (NTRS)

    Anders, E.; Larimer, J. W.

    1975-01-01

    A reply is made to previous criticisms of the claim that the range of accretion of ordinary chondrites can be narrowed to 500-420 K (from 560-405 K) using volatile metals as cosmothermometers. Questions concerning uncertainties in vapor pressure data, entropy of mixing, methods of analysis, uncertainties in condensation curves, metamorphic transport, alloy formation, condensation of Tl, condensation of In, and concordance with other thermometers (FeO contents of silicates) are addressed. It is concluded that the original claim is valid.

  16. A Cabonaceous Chondrite Dominated Lithology from the HED Parent; PRA 04401

    NASA Technical Reports Server (NTRS)

    Herrin, Jason S.; Zolensky, M. E.; Mittlefehldt, David W.

    2010-01-01

    The paired howardite breccias Mt. Pratt (PRA) 04401 and PRA 04402 are notable for their high proportion of carbonaceous chondrite clasts [1]. They consist predominantly of coarse (0.1-7 mm) diogenite (orthopyroxene), eucrite (plagioclase + pyroxene), and carbonaceous chondrite clasts set in a finer grained matrix of these same materials. Coarse C-chondrite clasts up to 7 mm are composed mainly of fine-grained phyllosilicates with lesser sulfides and high-mg# anhydrous magnesian silicates. Most of these clasts appear to be texturally consistent with CM2 classification [1] and some contain relict chondrules. The clasts are angular and reaction or alteration textures are not apparent in the surrounding matrix. PRA 04401 contains about 70 modal% C-chondrite clasts while PRA 04402 contains about 7%. Although many howardites are known to contain abundant C-chondrite clasts [2,3,4], PRA 04401 is, to our knowledge, the most chondrite-rich howardite lithology identified to date. Low EPMA totals from CM2-type clasts in other howardites suggest that they frequently contain 10 wt% or more water [2], a figure consistent with their mineralogy. PRA 04401, therefore, demonstrates the potential for hydrous lithologies with greater than 5 wt% water to occur locally within the nominally anhydrous HED parent body. Since the origin of this water is xenogenic, it might therefore be concentrated in portions of the asteroid surface where it would be more readily observable by remote sensing techniques. We plan to further examine C-chondrite clasts in PRA 04401/2 with the intent of establishing firm chemical classification, estimating water content, and evaluating their relationship with the host breccia. To help place them in context of the HED parent, we will also compare these breccias with other howardites to evaluate which lithologies are likely to be more prevalent on the asteroid surface.

  17. Ar-40/Ar-39 Age of Hornblende-bearing R Chondrite LAP 04840

    NASA Technical Reports Server (NTRS)

    Righter, K.; Cosca, M.

    2014-01-01

    Chondrites have a complex chronology due to several variables affecting and operating on chondritic parent bodies such as radiogenic heating, pressure and temperature variation with depth, aqueous alteration, and shock or impact heating [1]. Unbrecciated chondrites can record ages from 4.56 to 4.4 Ga that represent cooling in small parent bodies. Some brecciated chondrites exhibit younger ages (<<4 to 4.4 Ga) that may reflect the age of brecciation, disturbance, or shock and impact events (<< 4 Ga). A unique R chondrite was recently found in the LaPaz Icefield of Antarctica - LAP 04840 [2]. This chondrite contains approx.15% hornblende and trace amounts of biotite, making it the first of its kind. Studies have revealed an equigranular texture, mineral equilibria yielding equilibration near 650-700 C and 250-500 bars, hornblende that is dominantly OH-bearing (very little Cl or F), and high D/H ratios [8,9,10]. To help gain a better understanding of the origin of this unique sample, we have measured the Ar-40/Ar-39 age. Age of 4.290 +/- 0.030 Ga is younger than one would expect for a sample that has cooled within a small body [4], and one might instead attribute the age to a younger shock event, On the other hand, there is no evidence for extensive shock in this meteorite (shock stage S2; [3]), so this sample may have been reannealed after the shock event. This age is similar to Ar-Ar ages determined for some other R chondrites

  18. Variations of Chondrite Properties with Heliocentric Distance

    NASA Astrophysics Data System (ADS)

    Rubin, A. E.; Wasson, J. T.

    1995-09-01

    There are 12 well-established chondrite groups distinguishable by significant compositional hiatus among their compositional and petrographic characteristics. Because each group represents a different parent asteroid, formed in a distinct nebular region (and/or at a particular time), it is plausible that chondrite properties varied in a smooth fashion with heliocentric distance (HD). Oxidation state. Thermodynamic calculations indicate that the equilibrium FeO/(FeO+MgO) ratio increases with decreasing nebular temperature. Because the nebular temperature gradient decreased with HD, at all times inner nebular regions had a lower oxidation state than more distant regions. If the time of agglomeration increased with HD, outer-solar-system materials generally would have acquired more ferroan compositions. By these criteria we infer that enstatite chondrites formed closer to the Sun, OC at intermediate HD, and R chondrites and carbonaceous chondrites still farther from the Sun. Oxygen isotopic composition. The nearer the Sun, the higher the nebular temperature and the larger the fraction of infalling interstellar material that evaporated; this resulted in greater equilibration with nebular gas and greater isotopic homogeneity. Because the Earth, Moon and EH-EL chondrites lie on the terrestrial fractionation (TF) line on the standard three O-isotope diagram, and martian meteorites (Delta^(17)O=0.36 per mil) and eucrites (Delta^(17)O=-0.40 per mil) lie close to this line, we infer that the mean nebular (i.e., solar) O-isotopic composition was on or near the TF line. At >1 AU the absolute value of Delta^(17)O increased. We infer that EH and EL chondrites formed at a HD <1 AU; H, L and LL chondrites (mean Delta^(17)O = 0.73, 1.07 and 1.26 per mil) formed appreciably beyond Mars' distance of 1.5 AU (probably near 2.5 AU at the 3:1 Jupiter-period resonance); R chondrites (Delta^(17)O ~2.9 per mil) and CR, CM, CO, CV and CK chondrites (Delta^(17)O ~ -1.6, -2.3, -4.5, -3.4 and

  19. Noble gases in E-chondrites

    NASA Technical Reports Server (NTRS)

    Crabb, J.; Anders, E.

    1981-01-01

    The combination of noble gas data for 12 E-chondrites with literature data shows K-Ar ages greater than 4 AE for 14 out of 18 meteorites, while U, Th-He ages are often shorter. Cosmic ray exposure ages are found to differ systematically between types E4 and E6, with the respective, below-16 Myr and above-30 Myr values implying that the E-chondrite parent body predominantly contains a single petrologic type on the 1 km scale of individual impacts in contrast to the mixed parent bodies of the ordinary chondrites. Amounts of planetary gas in E4-E6 chondrites fall in the range for ordinary chondrites of types 4-6, but fail to correlate with petrologic type or volatile trace element contents, in contrast to the ordinary chondrites. Analyses of mineral separates show that the planetary gases are concentrated in an HFand HCl-insoluble mineral, similar to phase Q. The subsolar gases are located in an HCl- and HNO3-resistant phase.

  20. Source of potassium in shocked ordinary chondrites

    NASA Astrophysics Data System (ADS)

    Weirich, J. R.; Swindle, T. D.; Isachsen, C. E.; Sharp, T. G.; Li, C.; Downs, R. T.

    2012-12-01

    Argon-argon dating (a variation of potassium-argon dating) of ordinary chondrites is being used to reconstruct the collisional impact history of their parent bodies. However, due to the fine-grained, multi-mineral, highly shocked nature of chondrites, the sources of potassium (K) in these meteorites have not been fully identified. By locating and isolating the different sources prior to analysis, better ages can be obtained. To distinguish between possible sources, we have analyzed Chico and Northwest Africa 091 (both L6 chondrites) via K mass balance, Raman spectroscopy, and argon (Ar) diffusion studies. In accordance with previous studies on other ordinary chondrites, the Ar in these two chondrites is nearly equally split between two releases, and the lower temperature release is identified as sodium-rich feldspar. Various scenarios for the higher temperature release are investigated, but no scenario meets all the required criteria. The Ar activation energy of the higher temperature release is the same as pyroxene, but the pyroxene has no detectable K. The K mass balance shows feldspar can account for all the K in the chondrite; hence feldspar must be the ultimate source of the higher temperature release. Raman spectroscopy rules out a high-pressure phase of feldspar. Neither melt veins, nor feldspar inclusions in pyroxene, are abundant enough to account for the higher temperature release in these meteorites.

  1. Lunar and Planetary Science XXXV: Ordinary and Enstatite Chondrites

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session "Ordinary and Enstatite Chondrites" included the following reports:The Distribution of Molybdenum in the Indarch EH4 Chondrite; Cosmic-Ray Exposure Age and Heliocentric Distance of the Parent Body of E Chondrites ALH 85119 and MAC 88136; Further Observations of Fe-60-Ni-60 and Isotopic Systems in Sulfides from Enstatite Chondrites; Thermal Metamorphism in L Chondrites: Implications of Percent Mean Deviation in Olivine and Pyroxene; Cooling Rates and the Mn-53-Cr-53 Isotopic System of Yamato 86753, an Equilibrated Ordinary Chondrite; Production Rates of Cosmogenic Nuclides in the Knyahinya L-Chondrite; Preliminary Mineralogical Data from the Saratov (L4) Primitive Ordinary Chondrite; Phosphate Minerals in Semarkona; A Textural Comparison of Chondrules and Smelter-derived Dust: Implications Regarding Formation Conditions; and Modification of the Van Schmus & Wood Petrologic Classification for Lithic Fragments in the Chondritic Breccia Rumuruti.

  2. Early UV emission from disc-originated matter (DOM) in Type Ia supernovae in the double-degenerate scenario

    NASA Astrophysics Data System (ADS)

    Levanon, Naveh; Soker, Noam

    2017-09-01

    We show that the blue and UV excess emission in the first few days of some Type Ia supernovae (SNe Ia) can be accounted in the double-degenerate (DD) scenario by the collision of the SN ejecta with circumstellar matter that was blown by the accretion disc formed during the merger process of the two white dwarfs (WDs). We assume that in cases of excess early light, the disc blows the circumstellar matter, that we term disc-originated matter (DOM), hours to days before explosion. To perform our analysis, we first provide a model-based definition for early excess light, replacing the definition of excess light relative to a power-law fit to the rising luminosity. We then examine the light curves of the SNe Ia iPTF14atg and SN 2012cg, and find that the collision of the ejecta with a DOM in the frame of the DD scenario can account for their early excess emission. Thus, early excess light does not necessarily imply the presence of a stellar companion in the frame of the single-degenerate scenario. Our findings further increase the variety of phenomena that the DD scenario can account for, and emphasize the need to consider all different SN Ia scenarios when interpreting observations.

  3. Origin, composition and quality of suspended particulate organic matter in relation to freshwater inflow in a South Texas estuary

    NASA Astrophysics Data System (ADS)

    Lebreton, Benoit; Beseres Pollack, Jennifer; Blomberg, Brittany; Palmer, Terence A.; Adams, Leslie; Guillou, Gaël; Montagna, Paul A.

    2016-03-01

    South Texas has a semi-arid climate with a large interannual variability of freshwater inflows. This study sought to define how changes in freshwater inflow affect the composition, quantity and quality of suspended particulate organic matter (SPOM) in a South Texas estuary: the Mission-Aransas estuary. The study was implemented 1.5 months after a large rain event in September 2010 and continued for 10 months of drought conditions. The composition of SPOM originating from rivers, the Gulf of Mexico and the estuary were determined using stable isotopes (δ13C, δ15N and δ34S). The quantity and quality of SPOM were assessed using organic carbon content, chlorophyll a concentrations and C/chl a ratios. Our results demonstrated that autochthonous phytoplankton was the dominant component of SPOM in the Mission-Aransas estuary during droughts. Benthic organic matter from local primary producers (i.e., seagrass, salt marsh plants, benthic microalgae) did not influence SPOM composition, either as fresh material or as detritus. A comparison with a positive estuary (i.e., Sabine-Neches estuary, TX) indicates that decreases in freshwater inflow may lead to decreases of terrestrial organic matter inputs and to increase the ratio of autochtonous phytoplanktonic material in SPOM.

  4. Life's Late Digital Revolution and Why It Matters for the Study of the Origins of Life.

    PubMed

    Baum, David A; Lehman, Niles

    2017-08-25

    The information contained in life exists in two forms, analog and digital. Analog information is manifest mainly in the differing concentrations of chemicals that get passed from generation to generation and can vary from cell to cell. Digital information is encoded in linear polymers such as DNA and RNA, whose side chains come in discrete chemical forms. Here, we argue that the analog form of information preceded the digital. Acceptance of this dichotomy, and this progression, can help direct future studies on how life originated and initially complexified on the primordial Earth, as well as expected trajectories for other, independent origins of complex life.

  5. Chemical and physical studies of chondrites: 10. Cathodoluminescence and phase composition studies of metamorphism and nebular processes in chondrules of type 3 ordinary chondrites

    SciTech Connect

    DeHart, J.M.; Lu Jie; Benoit, P.H.; Sears, D.W.G. ); Lofgren, G.E. )

    1992-10-01

    The cathodoluminescence (CL) properties of eight type 3 ordinary chondrites and one L5 chondrite have been determined, and phenocryst and mesostasis compositions have been analyzed in the chondrules of four of them (Semarkona, type 3.0; Krymka, 3.1; Allan Hills A77214, 3.5; and Dhajala, 3.8) in order to investigate their origins and metamorphic history. In the present study, the authors discuss the CL properties of nine ordinary chondrites of a variety of petrologic types with particular emphasis on detailed studies of the compositions of the relevant phases in four of these: Semarkona (3.0), Krymka (3.1), Allan Hills A77214 (3.5), and Dhajala (3.8). They describe a means of classifying chondrules that is based on the composition of their two major components, the mesostasis and phenocrysts. The system is applicable to > 90-95% off the chondrules in a given meteorite and it describes the range of material produced by nebular material and of the effect of metamorphism on the chondrules. They also discuss the relevance of the results for the origin of the nine chondrite classes.

  6. Gravothermal collapse of self-interacting dark matter halos and the origin of massive black holes.

    PubMed

    Balberg, Shmuel; Shapiro, Stuart L

    2002-03-11

    Black hole formation is an inevitable consequence of relativistic core collapse following the gravothermal catastrophe in self-interacting dark matter (SIDM) halos. Very massive SIDM halos form supermassive black holes (SMBHs) > or about 10(6)M(middle dot in circle) directly. Smaller halos believed to form by redshift z = 5 produce seed black holes of (10(2)-10(3))M(middle dot in circle) which can merge and/or accrete to reach the observational SMBH range. This scenario for SMBH formation requires no baryons, no prior star formation, and no other black hole seed mechanism.

  7. Collisional erosion and the non-chondritic composition of the terrestrial planets.

    PubMed

    O'Neill, Hugh St C; Palme, Herbert

    2008-11-28

    The compositional variations among the chondrites inform us about cosmochemical fractionation processes during condensation and aggregation of solid matter from the solar nebula. These fractionations include: (i) variable Mg-Si-RLE ratios (RLE: refractory lithophile element), (ii) depletions in elements more volatile than Mg, (iii) a cosmochemical metal-silicate fractionation, and (iv) variations in oxidation state. Moon- to Mars-sized planetary bodies, formed by rapid accretion of chondrite-like planetesimals in local feeding zones within 106 years, may exhibit some of these chemical variations. However, the next stage of planetary accretion is the growth of the terrestrial planets from approximately 102 embryos sourced across wide heliocentric distances, involving energetic collisions, in which material may be lost from a growing planet as well as gained. While this may result in averaging out of the 'chondritic' fractionations, it introduces two non-chondritic chemical fractionation processes: post-nebular volatilization and preferential collisional erosion. In the latter, geochemically enriched crust formed previously is preferentially lost. That post-nebular volatilization was widespread is demonstrated by the non-chondritic Mn/Na ratio in all the small, differentiated, rocky bodies for which we have basaltic samples, including the Moon and Mars. The bulk silicate Earth (BSE) has chondritic Mn/Na, but shows several other compositional features in its pattern of depletion of volatile elements suggestive of non-chondritic fractionation. The whole-Earth Fe/Mg ratio is 2.1+/-0.1, significantly greater than the solar ratio of 1.9+/-0.1, implying net collisional erosion of approximately 10 per cent silicate relative to metal during the Earth's accretion. If this collisional erosion preferentially removed differentiated crust, the assumption of chondritic ratios among all RLEs in the BSE would not be valid, with the BSE depleted in elements according to their

  8. Are H/L Chondrites Associated with the Disruption of Comet C/1919 Q2 Metcalf?

    NASA Astrophysics Data System (ADS)

    Trigo-Rodriguez, J. M.; Williams, I. P.

    2016-08-01

    We present evidence from historic meteorite falls (e.g. Cali and Tieschitz) about the existence of a high-inclination meteoroid stream originated by the disruption of comet C/1919 Q2 Metcalf that is the main source of the H/L chondrite interloper.

  9. Comment on Mars as the Parent Body of the CI Carbonaceous Chondrites by J. E. Brandenburg

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.

    1996-01-01

    Geological and chemical data refute a martian origin for the CI carbonaceous chondrites. Here, I will first consider Brandenburg's [1996] proposal that the CI's formed as water-deposited sediments on Mars, and that these sediments had limited chemical interactions with their martian environment. Finally, I will address oxygen isotope ratios, the strongest link between the CIs and the martian meteorites.

  10. Terrigenous organic matter input to the Black Sea originating from different hinterland regimes

    NASA Astrophysics Data System (ADS)

    Kusch, S.; Rethemeyer, J.; Mollenhauer, G.

    2009-04-01

    The Black Sea as the world's largest anoxic basin has been shown to be a significant sink of terrigenous and phytoplankton derived organic material. The north-western part is dominated by a large shelf area, while in the SW and E Black Sea, steep slopes plunge into the anoxic zone at short distances to the shore. Major rivers draining into the Black Sea include the Danube River, the Dniester River, the Kuban and the Don River. These rivers and their tributaries transport huge amounts of suspended load to the Black Sea, eroded from mountain ranges including the Alps, the Carpathian Mountains and the Caucasus Mountains. However, the size, climate and ecology of the respective drainage areas and the near-shore topography differ substantially between the rivers. We show geochemical proxy data, bulk radiocarbon (14C) ages and compound-specific 14C ages of terrigenous biomarkers from core-top samples collected along three sample transects in front of the Danube and the Dniester river mouths in the NW Black Sea off Rumania and Ukraine, draining the Alps and the Carpathian Mountains, and just south of the Strait of Kerch, connecting the Black Sea to the Sea of Azov (drainage of the Caucasus Mountains). Two further core locations are situated in front of the Çoruh and Acharistsgali river mouths in the SE Black Sea off Georgia (Eastern Pontic Mountains) and north of the Gülüç and Çatalağci river mouths in the SW Black Sea off Turkey (Western Pontic Mountains), respectively. The samples range from the oxygenated surface waters to the anoxic deep basin and form transects along specific transport pathways. The Branched and Isoprenoid Tetraether index (BIT) is used to trace the terrigenous organic matter in marine sediments, and it is thought to represent mainly soil-derived materials. BIT-values show the expected pattern of high terrigenous input in front of the river mouths and decreasing values further offshore along the sampled transport trajectories. Proxies

  11. Provenance does matter: links between winter trophic segregation and the migratory origins of European robins.

    PubMed

    Catry, Paulo; Campos, Ana R; Granadeiro, José Pedro; Neto, Júlio M; Ramos, Jaime; Newton, Jason; Bearhop, Stuart

    2016-12-01

    Amongst migratory species, it is common to find individuals from different populations or geographical origins sharing staging or wintering areas. Given their differing life histories, ecological theory would predict that the different groups of individuals should exhibit some level of niche segregation. This has rarely been investigated because of the difficulty in assigning migrating individuals to breeding areas. Here, we start by documenting a broad geographical gradient of hydrogen isotopes (δ (2)H) in robin Erithacus rubecula feathers across Europe. We then use δ (2)H, as well as wing-tip shape, as surrogates for broad migratory origin of birds wintering in Iberia, to investigate the ecological segregation of populations. Wintering robins of different sexes, ages and body sizes are known to segregate between habitats in Iberia. This has been attributed to the despotic exclusion of inferior competitors from the best patches by dominant individuals. We find no segregation between habitats in relation to δ (2)H in feathers, or to wing-tip shape, which suggests that no major asymmetries in competitive ability exist between migrant robins of different origins. Trophic level (inferred from nitrogen isotopes in blood) correlated both with δ (2)H in feathers and with wing-tip shape, showing that individuals from different geographic origins display a degree of ecological segregation in shared winter quarters. Isotopic mixing models indicate that wintering birds originating from more northerly populations consume more invertebrates. Our multi-scale study suggests that trophic-niche segregation may result from specializations (arising in the population-specific breeding areas) that are transported by the migrants into the shared wintering grounds.

  12. Magnetite as Possible Template for the Synthesis of Chiral Organics in Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Chan, Q. H. S.; Zolensky, M. E.

    2014-01-01

    The main goal of the Japanese Aerospace Ex-ploration Agency (JAXA) Hayabusa-2 mission is to visit and return to Earth samples of a C-type asteroid (162173) 1999 JU3 in order to understand the origin and nature of organic materials in the Solar System. Life on Earth shows preference towards the set of organics with particular spatial arrangements, this 'selectivity' is a crucial criterion for life. With only rare exceptions, life 'determines' to use the left- (L-) form over the right- (D-) form of amino acids, resulting in a L-enantiomeric excess (ee). Recent studies have shown that L-ee is found within the alpha-methyl amino acids in meteorites [1, 2], which are amino acids with rare terrestrial occurrence, and thus point towards a plausible abiotic origin for ee. One of the proposed origins of chiral asymmetry of amino acids in meteorites is their formation with the presence of asymmetric catalysts [3]. The catalytic mineral grains acted as a surface at which nebular gases (CO, H2 and NH3) were allowed to condense and react through Fisher Tropsch type (FTT) syntheses to form the organics observed in meteorites [4]. Magnetite is shown to be an effective catalyst of the synthesis of amino acids that are commonly found in meteorites [5]. It has also taken the form as spiral magnetites (a.k.a. 'plaquettes'), which were found in various carbonaceous chondrites (CCs), including C2s Tagish Lake and Esseibi, CI Orgueil, and CR chondrites [e.g., 6, 7, 8]. In addition, L-ee for amino acids are common in the aqueously altered CCs, as opposed to the unaltered CCs [1]. It seems possible that the synthesis of amino acids with chiral preferences is correlated to the alteration process experienced by the asteroid parent body, and related to the configuration of spiral magnetite catalysts. Since C-type asteroids are considered to be enriched in organic matter, and the spectral data of 1999 JU3 indicates a certain de-gree of aqueous alteration [9], the Hayabusa-2 mission serves as

  13. Normal and reverse zoning in niningerite - A novel key parameter to the thermal histories of EH-chondrites

    NASA Astrophysics Data System (ADS)

    Ehlers, K.; El Gorsey, A.

    1988-04-01

    Niningerite zoning features in eight EH chondrites are characterized by means of reflected-light studies, backscattered-electron SEM, and EMPA (at 15 keV, with sample current 15 nA and beam resolution 500 nm). The results are presented in extensive tables, graphs, and micrographs and discussed in detail. In five of the chondrites, the zoning is found to be normal (Fe content decreasing from the core to the rim), consistent with origin in the solar nebula or the chondrite parent body. In the other three chondrites, however, the zoning is reversed (Fe content increasing toward the rim adjacent to troilite). This feature is attributed to inhomogeneous accretion (in the case of Qingzhen) or to either slow preaccretion cooling of FeS-rich niningerite or two-stage cooling (in the case of Indarch).

  14. Effects of Metamorphism on the Valence and Coordination of Titanium in Ordinary Chondrites

    SciTech Connect

    Simon, S.B.; Sutton, S.R.; Grossman, L.

    2012-04-02

    Despite years of study, the conditions under which ordinary chondrites were metamorphosed from grade 3 to grade 6 are not well defined. Wide ranges of peak temperature are inferred for each grade. The long-popular 'onion shell' model, in which higher metamorphic grade is attributed to greater depths of origin, implies a corresponding decrease in cooling rate with increasing grade, and there is disagreement as to whether or not this is observed. Redox conditions during chondrite metamorphism are also not well understood. Some workers have reported evidence for reduction, presumably by carbon, with increase in grade from 3-4, followed by oxidation during metamorphism to higher grades, but other work indicates little variation in fO{sub 2} as a function of metamorphic grade. During our investigation of the valence of Ti in planetary materials, we found high proportions of Ti{sup 3+} in olivine and pyroxene in chondrules in Semarkona (LL3.0) and low proportions in New Concord (L6) olivine, suggesting that Ti was oxidized during ordinary chondrite metamorphism. We have undertaken a study of L and LL chondrites of grades 3-6 to see how Ti valence and coordination vary with grade and to see if the variations can be used to constrain conditions of chondrite metamorphism.

  15. Mineralogy and petrology of two ordinary chondrites and their correlation with other meteorites

    NASA Astrophysics Data System (ADS)

    Owocki, Krzysztof; Pilski, Andrzej

    2009-01-01

    Two ordinary chondrites are compared and classified using transmitted and reflected light microscopy and electron microprobe analyses. Both meteorites were confiscated by the Polish Customs Service at the border with Belarus. The first meteorite (called in this paper Terespol-1) is a L/LL6 chondrite, its classification being supported by the equilibrated compositions of olivine and orthopyroxene and the presence of large recrystallized feldspars (< 150 μm). The specimen examined experienced weak shock metamorphism (S3) and moderate weathering (although metal in the inner part of the meteorite seems to be unaffected by oxidization). The other meteorite (called in this paper Terespol-2) is a LL6 chondrite which experienced weak shock metamorphism (S3) and is unaffected by weathering. The Terespol-2 meteorite shares its classification with the Dhofar 1401 chondrite but the lack of data prevents further correlation. Both meteorites have been correlated with known findings from the Meteoritical Bulletin database and an attempt is made to identify their place of origin (fall event). Results indicate that Terespol-1 is most closely related to the Dhofar 1316 chondrite and we suggest that both meteorites at least came from the same parent body.

  16. Oxygen isotopic composition of relict olivine grains in cosmic spherules: Links to chondrules from carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Rudraswami, N. G.; Prasad, M. Shyam; Nagashima, K.; Jones, R. H.

    2015-09-01

    Most olivine relict grains in cosmic spherules selected for the present study are pristine and have not been disturbed during their atmospheric entry, thereby preserving their chemical, mineralogical and isotopic compositions. In order to understand the origin of the particles, oxygen isotope compositions of relict olivine grains in twelve cosmic spherules collected from deep sea sediments of the Indian Ocean were studied using secondary ion mass spectrometry. Most of the data lie close to the CCAM (Carbonaceous Chondrite Anhydrous Mineral) line, with Δ17O ranging from -5‰ to 0‰. The data overlap oxygen isotopic compositions of chondrules from carbonaceous chondrites such as CV, CK, CR and CM, which suggests that chondrules from carbonaceous chondrites are the source of relict grains in cosmic spherules. Chemical compositions of olivine in cosmic spherules are also very similar to chondrule olivine from carbonaceous chondrites. Several olivine relict grains in three cosmic spherules are 16O-rich (Δ17O -21.9‰ to -18.7‰), similar to oxygen isotopic compositions observed in calcium aluminum rich inclusions (CAIs), amoeboid olivine aggregates (AOAs), and some porphyritic chondrules from carbonaceous chondrites. These grains appear to have recorded the initial oxygen isotopic composition of the inner solar nebula. Three olivine grains from two cosmic spherules have δ18O values >+20‰, which could be interpreted as mixing with stratospheric oxygen during atmospheric entry.

  17. The negligible chondritic contribution in the lunar soils water.

    PubMed

    Stephant, Alice; Robert, François

    2014-10-21

    Recent data from Apollo samples demonstrate the presence of water in the lunar interior and at the surface, challenging previous assumption that the Moon was free of water. However, the source(s) of this water remains enigmatic. The external flux of particles and solid materials that reach the surface of the airless Moon constitute a hydrogen (H) surface reservoir that can be converted to water (or OH) during proton implantation in rocks or remobilization during magmatic events. Our original goal was thus to quantify the relative contributions to this H surface reservoir. To this end, we report NanoSIMS measurements of D/H and (7)Li/(6)Li ratios on agglutinates, volcanic glasses, and plagioclase grains from the Apollo sample collection. Clear correlations emerge between cosmogenic D and (6)Li revealing that almost all D is produced by spallation reactions both on the surface and in the interior of the grains. In grain interiors, no evidence of chondritic water has been found. This observation allows us to constrain the H isotopic ratio of hypothetical juvenile lunar water to δD ≤ -550‰. On the grain surface, the hydroxyl concentrations are significant and the D/H ratios indicate that they originate from solar wind implantation. The scattering distribution of the data around the theoretical D vs. (6)Li spallation correlation is compatible with a chondritic contribution <15%. In conclusion, (i) solar wind implantation is the major mechanism responsible for hydroxyls on the lunar surface, and (ii) the postulated chondritic lunar water is not retained in the regolith.

  18. The negligible chondritic contribution in the lunar soils water

    PubMed Central

    Stephant, Alice; Robert, François

    2014-01-01

    Recent data from Apollo samples demonstrate the presence of water in the lunar interior and at the surface, challenging previous assumption that the Moon was free of water. However, the source(s) of this water remains enigmatic. The external flux of particles and solid materials that reach the surface of the airless Moon constitute a hydrogen (H) surface reservoir that can be converted to water (or OH) during proton implantation in rocks or remobilization during magmatic events. Our original goal was thus to quantify the relative contributions to this H surface reservoir. To this end, we report NanoSIMS measurements of D/H and 7Li/6Li ratios on agglutinates, volcanic glasses, and plagioclase grains from the Apollo sample collection. Clear correlations emerge between cosmogenic D and 6Li revealing that almost all D is produced by spallation reactions both on the surface and in the interior of the grains. In grain interiors, no evidence of chondritic water has been found. This observation allows us to constrain the H isotopic ratio of hypothetical juvenile lunar water to δD ≤ −550‰. On the grain surface, the hydroxyl concentrations are significant and the D/H ratios indicate that they originate from solar wind implantation. The scattering distribution of the data around the theoretical D vs. 6Li spallation correlation is compatible with a chondritic contribution <15%. In conclusion, (i) solar wind implantation is the major mechanism responsible for hydroxyls on the lunar surface, and (ii) the postulated chondritic lunar water is not retained in the regolith. PMID:25288758

  19. Extraterrestrial Amino Acids in Orgueil and Ivuna: Tracing the Parent Body of CI Type Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Meyer, Michael (Technical Monitor); Ehrenfreund, Pascale; Glavin, Daniel P.; Bota, Oliver; Cooper, George; Bada, Jeffrey

    2001-01-01

    Amino acid analyses using HPLC of pristine interior pieces of the CI carbonaceous chondrites Orgueil and Ivuna have found that beta-alanine, glycine, and gamma-amino-n-butyric acid (ABA) are the most abundant amino acids in these two meteorites, with concentrations ranging from approx. 600 to 2,000 parts per billion (ppb). Other alpha-amino acids such as alanine, alpha-ABA, alpha-aminoisobutyric acid (AIB), and isovaline are present only in trace amounts (less than 200 ppb). Carbon isotopic measurements of beta-alanine and glycine and the presence of racemic (D/L 1) alanine and beta-ABA in Orgueil suggest that these amino acids are extraterrestrial in origin. In comparison to the CM carbonaceous chondrites Murchison and Murray, the amino acid composition of the CIs is strikingly distinct, suggesting that these meteorites came from a different type of parent body, possibly an extinct comet, than did the CM carbonaceous chondrites.

  20. Magnetic properties of low-petrologic grade non-carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Sugiura, N.; Strangway, D. W.

    1982-12-01

    Magnetic properties and paleointensities are reported for several low-petrologic-grade noncarbonaceous chondrites. Enstatite chondrites are far more magnetic than others and record ancient fields of 7-16 Oe. Abee has nearly random NRM in clasts and matrix samples, suggesting preaccretional remanence. Indarch and Yamato-691 record high fields, but have a single direction of magnetization, so that it cannot be determined whether the magnetic record is of pre- or postaccretional origin. Bjurbole, Chainpur, Mezo Madaras, and Yamato-74191 have random (and stable) NRM components carried by plessite, indicating possible preaccretional remanence. However, Bjurbole and Mezo Madaras are thought to have been reheated to above 500 C after their accretion, and in that case the random NRM in these chondrites could not be preaccretional.

  1. Extraterrestrial Amino Acids in Orgueil and Ivuna: Tracing the Parent Body of CI Type Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Meyer, Michael (Technical Monitor); Ehrenfreund, Pascale; Glavin, Daniel P.; Bota, Oliver; Cooper, George; Bada, Jeffrey

    2001-01-01

    Amino acid analyses using HPLC of pristine interior pieces of the CI carbonaceous chondrites Orgueil and Ivuna have found that beta-alanine, glycine, and gamma-amino-n-butyric acid (ABA) are the most abundant amino acids in these two meteorites, with concentrations ranging from approx. 600 to 2,000 parts per billion (ppb). Other alpha-amino acids such as alanine, alpha-ABA, alpha-aminoisobutyric acid (AIB), and isovaline are present only in trace amounts (less than 200 ppb). Carbon isotopic measurements of beta-alanine and glycine and the presence of racemic (D/L 1) alanine and beta-ABA in Orgueil suggest that these amino acids are extraterrestrial in origin. In comparison to the CM carbonaceous chondrites Murchison and Murray, the amino acid composition of the CIs is strikingly distinct, suggesting that these meteorites came from a different type of parent body, possibly an extinct comet, than did the CM carbonaceous chondrites.

  2. Identification of solar nebula condensates in interplanetary dust particles and unequilibrated ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Kloeck, W.; Thomas, K. L.; Mckay, D. S.

    1989-01-01

    Orthopyroxene and olivine grains, low in FeO, but containing MnO contents up to 5 wt percent were found in interplanetary dust particles (IDP) collected in the stratosphere. The majority of olivines and pyroxenes in meteorites contain less than 0.5 wt percent MnO. Orthopyroxenes and olivines high in Mn and low in FeO have only been reported from a single coarse grained chondrule rim in the Allende meteorite and from a Tieschitz matrix augite grain. The bulk MnO contents of the extraterrestrial dust particles with high MnO olivines and pyroxenes are close to CI chondrite abundances. High MnO, low FeO olivines and orthopyroxenes were also found in the matrix of Semarkona, an unequilibrated ordinary chondrite. This may indicate a related origin for minerals in extraterrestrial dust particles and in the matrix of unequilibrated ordinary chondrites.

  3. Extraterrestrial amino acids in Orgueil and Ivuna: Tracing the parent body of CI type carbonaceous chondrites

    PubMed Central

    Ehrenfreund, Pascale; Glavin, Daniel P.; Botta, Oliver; Cooper, George; Bada, Jeffrey L.

    2001-01-01

    Amino acid analyses using HPLC of pristine interior pieces of the CI carbonaceous chondrites Orgueil and Ivuna have found that β-alanine, glycine, and γ-amino-n-butyric acid (ABA) are the most abundant amino acids in these two meteorites, with concentrations ranging from ≈600 to 2,000 parts per billion (ppb). Other α-amino acids such as alanine, α-ABA, α-aminoisobutyric acid (AIB), and isovaline are present only in trace amounts (<200 ppb). Carbon isotopic measurements of β-alanine and glycine and the presence of racemic (D/L ≈ 1) alanine and β-ABA in Orgueil suggest that these amino acids are extraterrestrial in origin. In comparison to the CM carbonaceous chondrites Murchison and Murray, the amino acid composition of the CIs is strikingly distinct, suggesting that these meteorites came from a different type of parent body, possibly an extinct comet, than did the CM carbonaceous chondrites. PMID:11226205

  4. Chemical and physical studies of type 3 chondrites. VIII - Thermoluminescence and metamorphism in the CO chondrites

    NASA Technical Reports Server (NTRS)

    Keck, Bradly D.; Sears, Derek W. G.

    1987-01-01

    A possible relationship between the thermoluminescence (TL) properties of CO chondrites and their metamorphic history was investigated by measuring the TL properties of seven normal CO chondrites and of the Colony and the Allan Hills A77307 (ALHA 77307) CO-related chondrites. With the exception of Colony and ALHA 77307, whose maximum induced TL emission is at approximately 350 C, the CO chondrites were found to exhibit two TL peaks: a 130 C and a 250 C peaks. Among the CO chondrites, the 130 C peak showed a 100-fold range in TL sensitivity and was found to correlate with various metamorphism-related phenomena, such as silicate heterogeneity, metal composition, and McSween's metamorphic subtypes. The peak at 250 did not show these correlations and, with exception of Colony, showed little variation.

  5. Petrology of Amoeboid Olivine Aggregates in Antarctic CR Chondrites: Comparison With Other Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Komatsu, M.; Fagan, T. J.; Yamaguchi, A.; Mikouchi, T.; Zolensky, M. E.; Yasutake, M.

    2016-01-01

    Amoeboid olivine aggregates (AOAs) are important refractory components of carbonaceous chondrites and have been interpreted to represent solar nebular condensates that experienced high-temperature annealing, but largely escaped melting. In addition, because AOAs in primitive chondrites are composed of fine-grained minerals (forsterite, anorthite, spinel) that are easily modified during post crystallization alteration, the mineralogy of AOAs can be used as a sensitive indicator of metamorphic or alteration processes. AOAs in CR chondrites are particularly important because they show little evidence for secondary alteration. In addition, some CR AOAs contain Mn-enriched forsterite (aka low-iron, Mn-enriched or LIME olivine), which is an indicator of nebular formation conditions. Here we report preliminary results of the mineralogy and petrology of AOAs in Antarctic CR chondrites, and compare them to those in other carbonaceous chondrites.

  6. Chemical and physical studies of type 3 chondrites. VIII - Thermoluminescence and metamorphism in the CO chondrites

    NASA Technical Reports Server (NTRS)

    Keck, Bradly D.; Sears, Derek W. G.

    1987-01-01

    A possible relationship between the thermoluminescence (TL) properties of CO chondrites and their metamorphic history was investigated by measuring the TL properties of seven normal CO chondrites and of the Colony and the Allan Hills A77307 (ALHA 77307) CO-related chondrites. With the exception of Colony and ALHA 77307, whose maximum induced TL emission is at approximately 350 C, the CO chondrites were found to exhibit two TL peaks: a 130 C and a 250 C peaks. Among the CO chondrites, the 130 C peak showed a 100-fold range in TL sensitivity and was found to correlate with various metamorphism-related phenomena, such as silicate heterogeneity, metal composition, and McSween's metamorphic subtypes. The peak at 250 did not show these correlations and, with exception of Colony, showed little variation.

  7. What Are Space Exposure Histories Telling Us about CM Carbonaceous Chondrites?

    NASA Technical Reports Server (NTRS)

    Takenouchi, A.; Zolensky, Michael E.; Nishiizumi, K.; Caffee, M.; Velbel, M. A.; Ross, K.; Zolensky, P.; Le, L.; Imae, N.; Yamaguchi, A.; Mikouchi, T.

    2013-01-01

    Chondrites are chemically primitive and carbonaceous (C) chondrites are potentially the most primitive among them because they mostly escaped thermal metamor-phism that affected the other chondrite groups and ratios of their major, non-volatile and most of the volatile elements are similar to those of the Sun. Therefore, C chondrites are ex-pected to retain a good record of the origin and early history of the solar system. Carbonaceous chondrites are chemically differentiated from other chondrites by their high Mg/Si ratios and refractory elements, and have experienced various degrees of aqueous alteration. They are subdivided into eight subgroups (CI, CM, CO, CV, CK, CR, CB and CH) based on major element and oxygen isotopic ratios. Their elemental ratios spread over a wide range though those of ordinary and enstatite chondrites are relatively uniform. It is critical to know how many sepa-rate bodies are represented by the C chondrites. In this study, CM chondrites, the most abundant carbona-ceous chondrites, are examined. They are water-rich, chon-drule- and CAI-bearing meteorites and most of them are brec-cias. High-temperature components such as chondrules, iso-lated olivine and CAIs in CMs are frequently altered and some of them are replaced by clay minerals and surrounded by sul-fides whose Fe was derived from mafic silicates. On the basis of degrees of aqueous alteration, CMs have been classified into subtypes from 1 to 2, although Rubin et al. [1] assigned subtype 1 to subtype 2 and subtype 2 to subtype 2.6 using various petrologic properties. The classification is based on petrographic and mineralogic properties. For example, though tochilinite (2[(Fe, Mg, Cu, Ni[])S] 1.57-1.85 [(Mg, Fe, Ni, Al, Ca)(HH)2]) clumps are produced during aqueous alteration, they disappear and sulfide appears with increasing degrees of aqueous alteration. Cosmic-ray exposure (CRE) age measurements of CM chondrites reveal an unusual feature. Though CRE ages of other chondrite

  8. The origin of dwarf galaxies, cold dark matter, and biased galaxy formation

    NASA Technical Reports Server (NTRS)

    Dekel, A.; Silk, J.

    1986-01-01

    A reexamination is conducted of the formation of dwarf, diffuse, metal-poor galaxies due to supernova-driven winds, in view of data on the systematic properties of dwarfs in the Local Group and Virgo Cluster. The critical condition for global gas loss as a result of the first burst of star formation is that the virial velocity lie below an approximately 100 km/sec critical value. This leads, as observed, to two distinct classes of galaxies, encompassing the diffuse dwarfs, which primarily originate from typical density perturbations, and the normal, brighter galaxies, including compact dwarfs, which can originate only from the highest density peaks. This furnishes a statistical biasing mechanism for the preferential formation of bright galaxies in denser regions, enhancing high surface brightness galaxies' clustering relative to the diffusive dwarfs.

  9. Postinflationary Higgs relaxation and the origin of matter-antimatter asymmetry.

    PubMed

    Kusenko, Alexander; Pearce, Lauren; Yang, Louis

    2015-02-13

    The recent measurement of the Higgs boson mass implies a relatively slow rise of the standard model Higgs potential at large scales, and a possible second minimum at even larger scales. Consequently, the Higgs field may develop a large vacuum expectation value during inflation. The relaxation of the Higgs field from its large postinflationary value to the minimum of the effective potential represents an important stage in the evolution of the Universe. During this epoch, the time-dependent Higgs condensate can create an effective chemical potential for the lepton number, leading to a generation of the lepton asymmetry in the presence of some large right-handed Majorana neutrino masses. The electroweak sphalerons redistribute this asymmetry between leptons and baryons. This Higgs relaxation leptogenesis can explain the observed matter-antimatter asymmetry of the Universe even if the standard model is valid up to the scale of inflation, and any new physics is suppressed by that high scale.

  10. Origin of organic matter in the protosolar nebula and in comets.

    PubMed

    Greenberg, J M; Shalabiea, O M; Mendoza-Gomez, C X; Schutte, W; Gerakines, P A

    1995-01-01

    Comet organics are traced to their origin in interstellar space. Possible sources of comet organics from solar nebula chemistry are briefly discussed. The infrared spectra of interstellar dust are compared with spectra of solar (space) irradiated laboratory organic residues and with meteorites. The spectra compare very favorably. The atomic composition of first generation laboratory organic residues compares favorably with that of comet Halley organics if divided into appropriate "volatile" (less refractory) and "refractory" (more refractory) complex organics.

  11. Origin of organic matter in the protosolar nebula and in comets

    NASA Technical Reports Server (NTRS)

    Greenberg, J. M.; Shalabiea, O. M.; Mendoza-Gomez, C. X.; Schutte, W.; Gerakines, P. A.

    1994-01-01

    Comet organics are traced to their origin in interstellar space. Possible sources of comet organics from solar nebula chemistry are briefly discussed. The infrared spectra of interstellar dust are compared with spectra of solar (space) irradiated laboratory organic residues and with meteorites. The spectra compare very favorably. The atomic composition of first generation laboratory organic residues compares favorably with that of comet Halley organics if divided into approrpriate 'volatile' (less refreactory) and 'refractory' (more refractory) complex organics.

  12. Isotopic evidence for the contemporary origin of high-molecular weight organic matter in oceanic environments

    NASA Astrophysics Data System (ADS)

    Santschi, Peter H.; Guo, Laodong; Baskaran, M.; Trumbore, Susan; Southon, John; Bianchi, Thomas S.; Honeyman, Bruce; Cifuentes, Luis

    1995-02-01

    Previous work has suggested that apparent old 14C ages for oceanic DOC are the result of mixing of different organic carbon fractions. This report provides direct evidence for a contemporary 14C age of a high-molecular-weight (HMW) fraction of colloidal organic carbon (≥10 kD). Colloidal organic matter, COM 10 (from 10 kDaltons (kD) to 0.2 μm), isolated from the upper water column of the Gulf of Mexico and the Middle Atlantic Bight (MAB) region, generally has a contemporary age (i.e., younger than a few decades), while COM 1 (from 1 kD to 0.2 μm), is apparently old: 380-4500 y BP. Thus, BMW COM 10 (3-5% of DOC) from the upper water column is derived from living particulate organic matter (POM) and cycles rapidly, while a significant fraction of low-molecular-weight (≤1 kD) DOM is likely more refractory, and cycles on much longer time scales. The presence of pigment biomarker compounds in COM 1 from the upper water column points to selected phytoplankton species as one of the sources of COM. Terrestrial carbon as another source of COM is suggested from the inverse correlation between Δ 14C and δ 13C values, as well as the increasing δ 13C values with increasing salinity. 234Th-derived turnover times of COM 10 and COM 1 from both the Gulf of Mexico and MAB are consistently short, 1-20 and 3-30 days, respectively. These short residence times support the hypothesis that 14C ages of colloidal fractions of DOC are the result of COM fractions being a mixture of several endmembers with fast and slow turnover rates.

  13. Changes in White Matter Microstructure Suggest an Inflammatory Origin of Neuropsychiatric Systemic Lupus Erythematosus.

    PubMed

    Magro-Checa, César; Ercan, Ece; Wolterbeek, Ron; Emmer, Bart; van der Wee, Nic J; Middelkoop, Huub A; Kruyt, Nyika D; Ronen, Itamar; van Buchem, Mark A; Huizinga, Tom W; Steup-Beekman, Gerda M

    2016-08-01

    To assess white matter (WM) and gray matter (GM) magnetization transfer ratio histogram peak heights (MTR-HPHs) in different subsets of patients with neuropsychiatric systemic lupus erythematosus (NPSLE) who have unremarkable findings on 3T magnetic resonance imaging of the brain and to evaluate whether these values could be used to highlight different clinically suspected underlying pathogenic processes or identify the clinical NPSLE status or whether they could be associated with a specific NPSLE syndrome. Sixty-four SLE patients with neuropsychiatric symptoms were included. The initial NPSLE diagnosis and suspected underlying pathogenic process were established by multidisciplinary evaluation. The final diagnosis was made after also considering the disease course 6-18 months later. Thirty-three patients with central nervous system (CNS) NPSLE and 31 SLE patients with neuropsychiatric symptoms unrelated to SLE (non-SLE-related NP) were included. Twenty SLE patients without neuropsychiatric symptoms and 36 healthy control subjects were included for comparison. Differences in the WM and GM mean MTR-HPHs and between the different NPSLE subgroups (CNS NPSLE diagnosis, NPSLE phenotype [inflammatory or ischemic], and clinical changes after treatment) and the relationship to NPSLE syndromes were evaluated. Patients with inflammatory NPSLE had significantly lower WM MTR-HPHs than did the healthy controls, the SLE patients, and the non-SLE-related NP patients. Cognitive disorder, mood disorder, and psychosis were related to lower WM MTR-HPH values and cerebrovascular symptoms to higher values. Furthermore, the mean MTR-HPHs in the WM increased when the clinical status of the NPSLE patients improved. Measurement of MTR-HPH of the WM has the potential to identify inflammatory NPSLE with CNS involvement. This finding underscores the usefulness of this technique for the detection of cerebral changes in NPSLE patients and for the assessment of clinical changes after treatment

  14. Magnetic Record of Ordinary Chondrite Chondrules

    NASA Astrophysics Data System (ADS)

    Kohout, T.; Kletetschka, G.

    2007-12-01

    The magnetic record of individual chondrules has been examined on two low-metamorphic grade ordinary chondrites - Bjurböle (L4) and Avanhandava (H4). The chondrule magnetic conglomerate study was done by removing oriented chondrules from the meteorite. The magnetic directions of the chondrules in both meteorites seems to be randomly oriented within both meteorites. The paleofield method based on the REM ratio (NRM/SIRM; Natural Remanent Magnetization / Saturation Isothermal Remanent Magnetization) calibrated for the TRM (Thermal Remanent Magnetization; Kletetschka et al., 2004) magnetization process reveals approximate paleofields between 5 μT and 20 μT (REM ~ 0.002) for Avanhandava chondrules and between 12 μT and 45 μT (REM ˜ 0.0015-0.0048) for Bjurböle chondrules. However, the timing of the magnetizing process remains unclear. The random pattern of the individual chondrule magnetic directions suggest that the chondrules were not remagnetized by recent terrestrial weathering nor by the exposure to the artificial magnetic fields. However the effect of post aggregation metamorphism (reaching 400 - 600°C) and impact related shock demagnetization on the parent body may be responsible for partial or complete loss of the magnetic information carried by the lower coercivity grains. In the case of Avanhandava meteorite this can be observed in the REM ratio. The values of REM ratio calculated in low AF (alternating Field) demagnetizing fields are progressively lower than in the higher AF fields. The Bjurböle meteorite contains significant fraction of the tetrataenite mineral. The origin of tetrataenite is related to the slow ordering of the FeNi lattice at temperatures below ~ 350°C). Thus the origin of tetrataenite must be post-metamorphic ruling out the high temperature TRM scenario. The origin of the magnetization in the Bjurböle chondrules are most likely associated to the post-metamorphic low temperature processes (i.e. electric discharges or impact

  15. Progressive aqueous alteration of CR carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Harju, Ellen R.; Rubin, Alan E.; Ahn, Insu; Choi, Byeon-Gak; Ziegler, Karen; Wasson, John T.

    2014-08-01

    The wide range in the degree of aqueous alteration of CR chondrites prompted us to formulate a numerical sequence for these rocks that ranges from petrologic type 2.0 to 2.8. (Hypothetical CR3.0 chondrites should be completely free of aqueous alteration effects.) About 70% of CR chondrites are slightly altered, type-2.8 rocks that exhibit heterogeneous alteration; these meteorites contain moderately abundant metallic Fe-Ni, no magnetite, and generally, a few chondrules with clear glassy mesostases. None of the chondrules in these rocks shows evidence of alteration of mafic silicate phenocrysts, but several chondrules are surrounded by phyllosilicate-rich rims that appear “smooth” when viewed by back-scattered-electron imaging. Matrix regions in slightly altered CR chondrites contain high S (∼3 wt.%), but some matrix patches in the same thin sections record alteration effects and contain appreciably less S (<1.5 wt.%). In CR chondrites that have been more-significantly altered (e.g., Renazzo and Al Rais), metallic Fe-Ni has been partially replaced by magnetite ± sulfide; mafic silicates have been partly altered to phyllosilicates, particularly along edges, fractures and twin boundaries. One of the most-altered CR chondrites (type-2.0 GRO 95577) contains abundant magnetite, additional oxide phases, iron carbonate, only very rare metallic Fe-Ni and essentially no mafic silicate grains. The whole-rock O-isotopic compositions of CR chondrites correlate with the degree of aqueous alteration: Δ17O ranges from ∼-2.6‰ in type-2.8 samples to ∼-0.4‰ in type 2.0.

  16. Roosevelt County 075: A petrologic chemical and isotopic study of the most unequilibrated known H chondrite

    NASA Technical Reports Server (NTRS)

    Mccoy, T. J.; Keil, K.; Ash, R. D.; Morse, A. D.; Pillinger, C. T.; Wieler, R.; Mayeda, T. K.; Clayton, R. N.; Benoit, P. H.; Sears, D. W. G.

    1993-01-01

    Roosevelt County (RC) 075 was recovered in 1990 as a single 258-gram stone. Classification of this meteorite is complicated by its highly unequilibrated nature and its severe terrestrial weathering, but we favor H classification. This is supported by O isotopes and estimates of the original Fe, Ni metal content. The O isotopic composition is similar to that of a number of reduced ordinary chondrites (e.g., Cerro los Calvos, Willaroy), although RC 075 exhibits no evidence of reduced mineral compositions. Chondrule diameters are consistent with classification as an L chondrite, but large uncertainties in chondrule diameters of RC 075 and poorly constrained means of H, L and LL chondrites prevent use of this parameter for reliable classification. Other parameters are compromised by severe weathering (e.g., siderophile element abundances) or unsuitable for discrimination between unequilibrated H, L and LL chondrites (e.g., Co in kamacite delta C-13). Petrologic subtype 3.2 +/- 0.1 is suggested by the degree of olivine heterogeneity, the compositions of chondrule olivines, the thermoluminescence sensitivity, the abundances and types of chondrules mapped on cathodoluminescence mosaics, and the amount of presolar SiC. The meteorite is very weakly shocked (S2), with some chondrules essentially unshocked and, thus, is classified as an H3.2(S2) chondrite. Weathering is evident by a LREE enrichment due to clay contamination, reduced levels of many siderophile elements, the almost total loss of Fe, Ni metal and troilite, and the reduced concentrations of noble gases. Some components of the meteorite (e.g., type IA chondrules, SiC) appear to preserve their nebular states, with little modification from thermal metamorphism. We conclude that RC 075 is the most equilibrated H chondrite yet recovered and may provide additional insights into the origin of primitive materials in the solar nebula.

  17. Assessing the Formation of Ungrouped Achondrite Northwest Africa 8186: Residue, Crystallization Product, or Recrystallized Chondrite?

    NASA Technical Reports Server (NTRS)

    Srinivasan, P.; McCubbin, F. M.; Agee, C. B.

    2016-01-01

    The recent discoveries of primitive achondrites, metachondrites, and type 7 chondrites challenge the long held idea that all chondrites and achondrites form on separate parent bodies. These meteorites have experienced metamorphic temperatures above petrologic type 6 and have partially melted to various degrees. However, because of their isotopic and compositional similarities to both undifferentiated and differentiated groups, the provenance of these 'type 6+' meteorites remains largely unknown. CK and CV chondrites have recently been linked to a few achondrites due to their strong compositional, mineralogical, and isotopic similarities], suggesting a common origin between these meteorites. Although CVs have generally undergone low degrees of alteration near petrologic type 3, CKs have experienced a wide range of thermal alteration from petrologic type 3 to 6. Thermal evolution models on early accreting bodies predict that an early forming body can partially differentiate due to radiogenic heating, and, as a result, form radial layers of material increasing in thermal grade (types 3 to 6+) from the unmelted chondritic surface towards the differentiated core.Northwest Africa (NWA) 8186 is an ungrouped achondrite that provides compelling evidence for higher degrees of thermal processing and/or melting and differentiation on some CK/CV parent bodies. NWA 8186 plots on the CCAM line on a 3-oxygen isotope diagram directly with CK and CV chondrites and also plots with the CKs in regards to Cr isotopes. This meteorite is dominated by Nickel(II)Oxygen-rich olivine (less than 80%), lacks iron metal, and contains four oxide phases, indicating a high fOxygen (above FMQ) similar to the CKs. Additionally, NWA 8186 does not contain chondrules. We have further investigated the origins of NWA 8186 by examining and comparing the bulk composition of this CK-like achondrite with CK and CV chondrites, allowing us to assess the various scenarios in which NWA 8186 may have formed from

  18. Roosevelt County 075: A petrologic chemical and isotopic study of the most unequilibrated known H chondrite

    NASA Technical Reports Server (NTRS)

    Mccoy, T. J.; Keil, K.; Ash, R. D.; Morse, A. D.; Pillinger, C. T.; Wieler, R.; Mayeda, T. K.; Clayton, R. N.; Benoit, P. H.; Sears, D. W. G.

    1993-01-01

    Roosevelt County (RC) 075 was recovered in 1990 as a single 258-gram stone. Classification of this meteorite is complicated by its highly unequilibrated nature and its severe terrestrial weathering, but we favor H classification. This is supported by O isotopes and estimates of the original Fe, Ni metal content. The O isotopic composition is similar to that of a number of reduced ordinary chondrites (e.g., Cerro los Calvos, Willaroy), although RC 075 exhibits no evidence of reduced mineral compositions. Chondrule diameters are consistent with classification as an L chondrite, but large uncertainties in chondrule diameters of RC 075 and poorly constrained means of H, L and LL chondrites prevent use of this parameter for reliable classification. Other parameters are compromised by severe weathering (e.g., siderophile element abundances) or unsuitable for discrimination between unequilibrated H, L and LL chondrites (e.g., Co in kamacite delta C-13). Petrologic subtype 3.2 +/- 0.1 is suggested by the degree of olivine heterogeneity, the compositions of chondrule olivines, the thermoluminescence sensitivity, the abundances and types of chondrules mapped on cathodoluminescence mosaics, and the amount of presolar SiC. The meteorite is very weakly shocked (S2), with some chondrules essentially unshocked and, thus, is classified as an H3.2(S2) chondrite. Weathering is evident by a LREE enrichment due to clay contamination, reduced levels of many siderophile elements, the almost total loss of Fe, Ni metal and troilite, and the reduced concentrations of noble gases. Some components of the meteorite (e.g., type IA chondrules, SiC) appear to preserve their nebular states, with little modification from thermal metamorphism. We conclude that RC 075 is the most equilibrated H chondrite yet recovered and may provide additional insights into the origin of primitive materials in the solar nebula.

  19. The classification and complex thermal history of the enstatite chondrites

    NASA Technical Reports Server (NTRS)

    Zhang, Yanhong; Benoit, Paul H.; Sears, Derek W. G.

    1995-01-01

    We have carried out instrumental neutron activation analysis of 11 enstatite chondrites and electron microprobe analyses of 17 enstatite chondrites, most of which were previously little described. We report here the third known EH5 chondrite (LEW 88180) and an unusual EL6 chondrite (LEW 87119), new data on four EL3 chondrites (ALH 85119, EET 90299, PCA 91020, and MAC 88136, which is paired with MAC 88180 and MAC 88184), the second EL5 chondrite (TIL 91714), and an unusual metal-rich and sulfide-poor EL3 chondrite (LEW 87223). The often discussed differences in mineral composition displayed by the EH and EL chondrites are not as marked after the inclusion of the new samples in the database, and the two classes apparently experienced a similar range of equilibrium temperatures. However, texturally the EL chondrites appear to have experienced much higher levels of metamorphic alteration than EH chondrites of similar equilibration temperatures. Most of the petrologic type criteria are not applicable to enstatite chondrites and, unlike the ordinary chondrites, texture and mineralogy reflect different aspects of the meteorite history. We therefore propose that the existing petrologic type scheme not be used for enstatite chondrites. We suggest that while 'textural type' reflects peak metamorphic temperatures, the 'mineralogical type' reflects equilibration during postmetamorphic (probably regolith) processes. Unlike the ordinary chondrites and EH chondrites, EL chondrites experienced an extensive low-temperature metamorphic episode. There are now a large number of enstatite meteorite breccias and impact melts, and apparently surface processes were important in determining the present nature of the enstatite chondrites.

  20. The classification and complex thermal history of the enstatite chondrites

    NASA Astrophysics Data System (ADS)

    Zhang, Yanhong; Benoit, Paul H.; Sears, Derek W. G.

    1995-05-01

    We have carried out instrumental neutron activation analysis of 11 enstatite chondrites and electron microprobe analyses of 17 enstatite chondrites, most of which were previously little described. We report here the third known EH5 chondrite (LEW 88180) and an unusual EL6 chondrite (LEW 87119), new data on four EL3 chondrites (ALH 85119, EET 90299, PCA 91020, and MAC 88136, which is paired with MAC 88180 and MAC 88184), the second EL5 chondrite (TIL 91714), and an unusual metal-rich and sulfide-poor EL3 chondrite (LEW 87223). The often discussed differences in mineral composition displayed by the EH and EL chondrites are not as marked after the inclusion of the new samples in the database, and the two classes apparently experienced a similar range of equilibrium temperatures. However, texturally the EL chondrites appear to have experienced much higher levels of metamorphic alteration than EH chondrites of similar equilibration temperatures. Most of the petrologic type criteria are not applicable to enstatite chondrites and, unlike the ordinary chondrites, texture and mineralogy reflect different aspects of the meteorite history. We therefore propose that the existing petrologic type scheme not be used for enstatite chondrites. We suggest that while 'textural type' reflects peak metamorphic temperatures, the 'mineralogical type' reflects equilibration during postmetamorphic (probably regolith) processes. Unlike the ordinary chondrites and EH chondrites, EL chondrites experienced an extensive low-temperature metamorphic episode. There are now a large number of enstatite meteorite breccias and impact melts, and apparently surface processes were important in determining the present nature of the enstatite chondrites.

  1. The classification and complex thermal history of the enstatite chondrites

    NASA Technical Reports Server (NTRS)

    Zhang, Yanhong; Benoit, Paul H.; Sears, Derek W. G.

    1995-01-01

    We have carried out instrumental neutron activation analysis of 11 enstatite chondrites and electron microprobe analyses of 17 enstatite chondrites, most of which were previously little described. We report here the third known EH5 chondrite (LEW 88180) and an unusual EL6 chondrite (LEW 87119), new data on four EL3 chondrites (ALH 85119, EET 90299, PCA 91020, and MAC 88136, which is paired with MAC 88180 and MAC 88184), the second EL5 chondrite (TIL 91714), and an unusual metal-rich and sulfide-poor EL3 chondrite (LEW 87223). The often discussed differences in mineral composition displayed by the EH and EL chondrites are not as marked after the inclusion of the new samples in the database, and the two classes apparently experienced a similar range of equilibrium temperatures. However, texturally the EL chondrites appear to have experienced much higher levels of metamorphic alteration than EH chondrites of similar equilibration temperatures. Most of the petrologic type criteria are not applicable to enstatite chondrites and, unlike the ordinary chondrites, texture and mineralogy reflect different aspects of the meteorite history. We therefore propose that the existing petrologic type scheme not be used for enstatite chondrites. We suggest that while 'textural type' reflects peak metamorphic temperatures, the 'mineralogical type' reflects equilibration during postmetamorphic (probably regolith) processes. Unlike the ordinary chondrites and EH chondrites, EL chondrites experienced an extensive low-temperature metamorphic episode. There are now a large number of enstatite meteorite breccias and impact melts, and apparently surface processes were important in determining the present nature of the enstatite chondrites.

  2. Fossil bacterial ecosystem at methane seeps - Origin of organic matter from Be'eri sulfur deposit, Israel

    NASA Astrophysics Data System (ADS)

    Burhan, R. Y. P.; Trendel, J. M.; Adam, P.; Wehrung, P.; Albrecht, P.; Nissenbaum, A.

    2002-12-01

    The Be'eri sulfur mine (Israel) is a unique deposit mainly composed of sandstone intercalated with biogenic mats and possessing organic matter exceptionally depleted in 13C. Molecular and isotopic studies of free and bound biomarkers were performed to unravel the source of the organic matter co-occurring with sulfur in this deposit and to propose a paleoenvironmental model of bacterial life in a type of extreme environment. They showed that the biomarkers are all extremely 13C-depleted and almost exclusively composed of hopanoids and biphytane derivatives of bacterial origin, notably methanotrophic bacteria and acidophilic archaea. δ 13C values of individual components and of bulk organic carbon are in the -80% to -90% range and are among the lowest values ever measured for hopanoids. Organic matter in the sandstone and the mats differ mainly by the occurrence of 3-methylated hopanoids in the mats, which may reflect either different bacterial populations or different conditions of growth. These data demonstrate that the complete biomass of this deposit primarily derives from methanotrophic hopanoid-synthesizing bacteria consuming methane having seeped toward the surface, and that all other organisms - apparently only archaea and bacteria - must have been thriving on methane-derived carbon (methane, CO 2, biomass of methanotrophic bacteria). Unambiguous evidence for photosynthetic organisms in the environment of deposition could not be found. The Be'eri sulfur deposit is thus a fossil remain of an exclusively bacterial ecosystem fueled by methane as sole carbon source and having developed in an interstitial aqueous medium within the sandstone. Elemental sulfur from the deposit probably originates from the oxidation of hydrogen sulfide seeping along with methane, which could have been oxidized either abiotically or biologically by sulfur-oxidizing Beggiatoa-like bacteria and archaea. Further oxidation of elemental sulfur might explain the high acidity of the deposit

  3. Tracing the origin of dissolved organic matter (DOM) in subterranean estuaries using colored DOM and amino acids

    NASA Astrophysics Data System (ADS)

    Kim, T.; Kwon, E.; Kim, G.

    2011-12-01

    In order to determine the origin of dissolved organic matter (DOM) in the subterranean estuary (STE), the mixing zone of fresh terrestrial groundwater and recirculating seawater in a coastal permeable aquifer, we conducted water sampling from two STEs with different geological settings: (1) Jeju Island beaches (Hwasun and Samyang), which are composed of volcanic rocks and sandy sediments, and (2) Hampyeong beach, which is located in a large intertidal, sandy flat zone. The distributions of salinity, total hydrolysable amino acids (THAA), dissolved organic carbon (DOC), and colored DOM (CDOM) were measured for groundwater samples in these STEs. In the Hwasun STE, the humic-like peak decreases with increasing salinity, whereas the protein-like peak does not show a clear relationship with salinity. In contrast, in the Samyang STE, both humic-like peak and protein-like peak increase with increasing salinity. These contrasting results indicate that DOM in the Hwasun STE originates mainly from terrestrial inputs, while that in the Samyang STE originates mainly from biological and/or microbial activities. In the Hampyeong STE, we observed good correlations among the biodegradation index, alanine D/L ratios, THAA concentrations, DOC, and CDOM index (both humic-like and protein-like). Together with their geographical distribution patterns, these correlations indicate that DOM in the Hampyeong STE is mainly derived from marine sediments in the course of seawater recirculation. Our study shows that CDOM and amino acids are excellent tracers of DOM in the STE where DOM is derived from diverse sources.

  4. Origin of particulate matter and gaseous precursors in the Paris Megacity: Results from intensive campaigns, long term measurements and modelling

    NASA Astrophysics Data System (ADS)

    Beekmann, Matthias; Petetin, Hervé; Zhang, Qijie; Prevot, André S. H.; Sciare, Jean; Gros, Valérie; Ghersi, Véronique; Rosso, Amandine; Crippa, Monica; Zotter, Peter; Freutel, Fredericke; Poulain, Laurent; Freney, Evelyne; Sellegri, Karine; Drewnick, Frank; Borbon, Agnès; Wiedensohler, Aflred; Pandis, Spyros N.; Baltensperger, Urs

    2016-04-01

    Uncertainties on the origin of primary and secondary particulate matter and its gaseous precursors in megacities is still large and needs to be reduced. A detailed characterization of air quality in Paris (France), a megacity of more than 10 million inhabitants, during two one month intensive campaigns (MEGAPOLI) and from additional one year observations (PARTICULATE and FRANCIPOL), revealed that about 70% of the fine particulate matter (PM) at urban background is transported on average into the megacity from upwind regions. While advection of sulfate is well documented for other megacities, there was a surprisingly high contribution from long-range transport for both nitrate and organic aerosol. The data set of urban local and advected PM concentrations in the Paris area were used for a thorough evaluation of the CHIMERE model and revealed error compensation for the local and advected components of organic matter and nitrate. During spring time, CHIMERE simulations overestimate the sensitivity of ammonium nitrate peaks to NH3, because (i) they underestimate the urban background NH3 levels, probably due to neglecting enhanced NH3 emissions for larger temperatures, and because they overestimate HNO3. However, from an ensemble of mobile Max-DOAS NO2 column and airborne NOy measurements around Paris, no clear sign on a NOx emission bias in the TNO-Airparif data set was made evident. The origin of organic PM was investigated by a comprehensive analysis of aerosol mass spectrometer (AMS), radiocarbon and tracer measurements during two intensive campaigns. Primary fossil fuel combustion emissions contributed less than 20% in winter and 40% in summer to carbonaceous fine PM, unexpectedly little for a megacity. Cooking activities and, during winter, residential wood burning are the major primary organic PM sources. This analysis suggests that the major part of secondary organic aerosol is of modern origin, i.e. from biogenic precursors and from wood burning. Implementation

  5. Prebiological Synthesis Organic Matter and Origin of Life in Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Snytnikov, V. N.

    2017-05-01

    Processes and conditions around new born Sun and possibly other young stars led to the origin of life in the circumstellar disc in a few million years. Than the circumsolar biosphere evolved to its current earth state. In agreement with the main results of the natural sciences and the theory of self-organization, several stages are necessary for the life to emerge on the Earth. Nowday we can specify "The cold prehistiry of the life", "RNA-world", "Preplanet biosphere", "Destructive biosphere", "Earth of bacteria".

  6. I-Xe ages of enstatite chondrites

    NASA Astrophysics Data System (ADS)

    Hopp, Jens; Trieloff, Mario; Ott, Ulrich

    2016-02-01

    In order to elucidate the early thermal history of enstatite chondrite parent bodies we determined 129I-129Xe whole rock ages of enstatite chondrites (5 EH, 2 EL, one EH impact melt) relative to the Shallowater reference meteorite (4562.3 ± 0.4 Ma, all errors are 1σ). I-Xe ages of both EL6 chondrites (LON 94100: -4.38 ± 0.60 Ma and Neuschwanstein: -3.87 ± 0.73 Ma - negative sign indicates ages younger than Shallowater) agree well with data of other EL6 chondrites. LON 94100 displayed a second isochron at lower temperatures equivalent to a younger age of -5.25 ± 1.17 Ma, perhaps reflecting different retention temperatures of respective carrier phases during sequential cooling. The enstatite chondrites Abee (EH4), Indarch (EH4), EET 96135 (EH4/5) and St. Marks (EH5) encompass a I-Xe age range of +0.57 ± 1.05 Ma (EET 96135 #1) to -0.45 ± 0.72 Ma (Abee), again in agreement with previously reported ages of EH chondrites. Only the age of St. Marks differs strongly from previously reported younger ages, now being more in accordance with other members of the EH clan. The EH3 chondrite Sahara 97096 showed the youngest I-Xe age of -7.87 ± 0.46 Ma distinctly younger than other I-Xe ages of EH chondrites, including other EH3s. Due to the apparent high retention temperature of the I-Xe system in enstatite (estimated >800 °C) this young age implies a later resetting of the I-Xe system by a severe thermal, likely impact-induced, event. The EH impact melt LAP 02225 records a similarly young thermal event. Though no isochron relationship could be established, the data fall within an apparent I-Xe age range of +5 to +15 Ma, similar to Sahara 97096. Overall, EH chondrite parent body experienced a thermal history determined by a complex interplay between impact disturbances and parent body metamorphism.

  7. The origin and function of dissolved organic matter in agro-urban coastal streams

    NASA Astrophysics Data System (ADS)

    Petrone, Kevin C.; Fellman, Jason B.; Hood, Eran; Donn, Michael J.; Grierson, Pauline F.

    2011-03-01

    Streams draining urban and agriculture catchments are often a source of inorganic nutrients to downstream aquatic ecosystems, but little is known about how changes in land use influence the quality and biodegradability of dissolved organic matter (DOM). We used parallel factor analysis of excitation-emission fluorescence spectroscopy and biodegradation incubations to examine how DOM composition influences bioavailable dissolved organic carbon (DOC) in surface waters of urban and agricultural catchments during summer (low flow), winter (high flow) and spring (flow recession). Percent bioavailable DOC was variable for all catchments (2-57%) and negatively related to percent humic-like fluorescence, but positively related to percent protein-like fluorescence and simple fluorescence metrics of DOM precursor material (fluorescence index and β:α values). Conversely, highly variable DOC concentrations (2-140 mg L-1) were negatively related to protein-like fluorescence and positively related to humic-like fluorescence. Elevated concentrations of DOC (>30 mg L-1) in agro-urban streams revealed fluorescence indices (<1.3) typical of wetland and forest-dominated ecosystems, suggesting that enriched stream DOM is either derived from the destabilization of legacy soil carbon or currently produced from remnant wetlands and patches of native vegetation. Overall, we demonstrate that fluorescence characteristics can be used to predict bioavailable DOC in human-dominated catchments to better understand the flow of carbon and nutrients in aquatic food webs for improved monitoring and management of coastal ecosystems.

  8. Polymer Physics Prize Talk: Topological Constraints Matter -- or Back to the Origin

    NASA Astrophysics Data System (ADS)

    Kremer, Kurt

    2011-03-01

    Topological constraints, being permanent or temporal, influence many properties of soft matter, especially polymers. While at a first glance the simple Rouse models describes the motion of short chains surprisingly well, the fact that chains cannot cut through each other dominates the dynamics of long chain melts, ring polymers and the relaxation in networks and gels. Furthermore new phenomena in special melts and mixtures even make this more obvious. The talk will review some developments and will also address new problems linked to material science as well as biology. To illustrate the importance of topological constraints, numerical simulations for a melt on non concatenated ring polymers with and without linear contaminants will be presented. While the static properties of long rings can be rationalized by the concept of a crumpled globule, dynamic properties are much less understood. Our simulations clearly show that diffusion and stress relaxation in such a system of globules decouple. In addition the first results for non concatenated rings added to a melt of linear polymers and for a few linear polymers added to a melt of rings will be discussed. The work over the years benefited from intense and fruitful collaborations with many colleagues. For the topics discussed above I especially want to thank K. Binder, G. S. Grest. B. Duenweg, R. Everaers, M. Pütz, A. Yu Grosberg and J. Halverson.

  9. Disentangling the Potential Dark Matter Origin of LIGO’s Black Holes

    NASA Astrophysics Data System (ADS)

    Magee, Ryan; Hanna, Chad

    2017-08-01

    The nature of dark matter (DM) remains one of the biggest open questions in physics. One intriguing DM candidate, primordial black holes (PBHs), has faced renewed interest following the Laser Interferometer Gravitational-wave Observatory’s (LIGO) detection of gravitational waves from merging stellar mass black holes. While subsequent work has ruled out the possibility that DM could consist solely of black holes similar to those that LIGO has detected with masses above 10 {M}⊙ , LIGO’s connection to DM remains unknown. In this work, we consider a distribution of PBHs that accounts for all of the DM, is consistent with all of LIGO’s observations arising from PBH binaries, and resolves tension in previous surveys of microlensing events in the Milky Way halo. The PBH mass distribution that we consider offers an important prediction—LIGO may detect black holes smaller than have ever been observed with ˜1% of the black holes it detects having a mass less than the mass of our Sun and ˜10% with masses in the mass gap. Approximately one year of operating advanced LIGO at design sensitivity should be adequate to begin to see a hint of a primordial black hole mass distribution. Detecting PBH binaries below a solar mass will be readily distinguishable from other known compact binary systems, thereby providing an unambiguous observational window for advanced LIGO to pin down the nature of DM.

  10. Identification, abundance and origin of atmospheric organic particulate matter in a Portuguese rural area

    NASA Astrophysics Data System (ADS)

    Pio, C. A.; Alves, C. A.; Duarte, A. C.

    Respirable suspended particles high-volume samples were collected from a coastal-rural site in the centre of Portugal in August 1997 and their solvent-extractable organic compounds were subjected to characterisation by gas chromatography-mass spectrometry. Particles were also analysed by a thermal/optical technique in order to determine their black and organic carbon content. The total lipid extract yields ranged from 20 to 63 μg m -3, containing mainly aliphatic hydrocarbons such as n-alkanes, acids, alcohols, aldehydes, ketones and polycyclic aromatic hydrocarbons. The higher input of vascular plant wax components was demonstrated by the distribution patterns of the n-alkanes, n-alkanoic acids and n-alkanols homologous series, with C max at C 29, C 22/C 24 and C 30, respectively. The CPI values for these series were in the range 1.8-9.7, being indicative of recent biogenic input from microbial lipid residues and flora epicuticular components. Specific natural constituents (e.g. phytosterols, terpenes, etc.) were identified as molecular markers. Some oxidation products from volatile organic precursors were also present in the aerosols. In addition, all samples had a component of petroleum hydrocarbons representing urban and vehicular emissions probably transported from the nearest cities and from the motorway in the vicinity. This data set could be used to make a mass balance with organic carbon, organic extracts and elutable matter, permitting also the comparison with lipid signatures observed for other regions.

  11. Light dark matter, naturalness, and the radiative origin of the electroweak scale

    SciTech Connect

    Altmannshofer, Wolfgang; Bardeen, William A.; Bauer, Martin; Carena, Marcela; Lykken, Joseph D.

    2015-01-09

    We study classically scale invariant models in which the Standard Model Higgs mass term is replaced in the Lagrangian by a Higgs portal coupling to a complex scalar field of a dark sector. We focus on models that are weakly coupled with the quartic scalar couplings nearly vanishing at the Planck scale. The dark sector contains fermions and scalars charged under dark SU(2) × U(1) gauge interactions. Radiative breaking of the dark gauge group triggers electroweak symmetry breaking through the Higgs portal coupling. Requiring both a Higgs boson mass of 125.5 GeV and stability of the Higgs potential up to the Planck scale implies that the radiative breaking of the dark gauge group occurs at the TeV scale. We present a particular model which features a long-range abelian dark force. The dominant dark matter component is neutral dark fermions, with the correct thermal relic abundance, and in reach of future direct detection experiments. The model also has lighter stable dark fermions charged under the dark force, with observable effects on galactic-scale structure. Collider signatures include a dark sector scalar boson with mass ≲ 250 GeV that decays through mixing with the Higgs boson, and can be detected at the LHC. As a result, the Higgs boson, as well as the new scalar, may have significant invisible decays into dark sector particles.

  12. Light dark matter, naturalness, and the radiative origin of the electroweak scale

    DOE PAGES

    Altmannshofer, Wolfgang; Bardeen, William A.; Bauer, Martin; ...

    2015-01-09

    We study classically scale invariant models in which the Standard Model Higgs mass term is replaced in the Lagrangian by a Higgs portal coupling to a complex scalar field of a dark sector. We focus on models that are weakly coupled with the quartic scalar couplings nearly vanishing at the Planck scale. The dark sector contains fermions and scalars charged under dark SU(2) × U(1) gauge interactions. Radiative breaking of the dark gauge group triggers electroweak symmetry breaking through the Higgs portal coupling. Requiring both a Higgs boson mass of 125.5 GeV and stability of the Higgs potential up tomore » the Planck scale implies that the radiative breaking of the dark gauge group occurs at the TeV scale. We present a particular model which features a long-range abelian dark force. The dominant dark matter component is neutral dark fermions, with the correct thermal relic abundance, and in reach of future direct detection experiments. The model also has lighter stable dark fermions charged under the dark force, with observable effects on galactic-scale structure. Collider signatures include a dark sector scalar boson with mass ≲ 250 GeV that decays through mixing with the Higgs boson, and can be detected at the LHC. As a result, the Higgs boson, as well as the new scalar, may have significant invisible decays into dark sector particles.« less

  13. Coordinated Isotopic and Mineral Characterization of Highly Fractionated 18O-Rich Silicates in the Queen Alexandra Range 99177 CR3 Chondrite

    NASA Technical Reports Server (NTRS)

    Nguyen, A. N.; Keller, L. P.; Messenger, S.; Rahman, Z.

    2016-01-01

    Carbonaceous chondrites contain a mixture of solar system condensates, pre-solar grains, and primitive organic matter. Each of these materials record conditions and processes in different regions of the solar nebula, on the meteorite parent body, and beyond the solar system. Oxygen isotopic studies of meteorite components can trace interactions of distinct oxygen isotopic reservoirs in the early solar system and secondary alteration processes. The O isotopic compositions of the earliest solar system condensates fall along a carbonaceous chondrite anhydrous mineral (CCAM) line of slope approximately 1 in a plot of delta 17O against delta 18O. This trend is attributed to mixing of material from 16O-poor and 16O-rich reservoirs. Secondary processing can induce mass-dependent fractionation of the O isotopes, shifting these compositions along a line of slope approximately 0.52. Substantial mass-dependent fractionation of O isotopes has been observed in secondary minerals in CAIs, calcite, and FUN inclusions. These fractionations were caused by significant thermal or aqueous alteration. We recently reported the identification of four silicate grains with extremely fractionated O isotopic ratios (delta 18O equals 37 - 55 per mille) in the minimally altered CR3 chondrite QUE 99177. TEM analysis of one grain indicates it is a nebular condensate that did not experience substantial alteration. The history of these grains is thus distinct from those of the aforementioned fractionated materials. To constrain the origin of the silicate grains, we conducted further Mg and Fe isotopic studies and TEM analyses of two grains.

  14. Identification of a Compound Spinel and Silicate Presolar Grain in a Chondritic Interplanetary Dust Particle

    NASA Technical Reports Server (NTRS)

    Nguyen, A. N.; Nakamura-Messenger, K.; Messenger, S.; Keller, L. P.; Kloeck, W.

    2014-01-01

    Anhydrous chondritic porous interplanetary dust particles (CP IDPs) have undergone minimal parent body alteration and contain an assemblage of highly primitive materials, including molecular cloud material, presolar grains, and material that formed in the early solar nebula [1-3]. The exact parent bodies of individual IDPs are not known, but IDPs that have extremely high abundances of presolar silicates (up to 1.5%) most likely have cometary origins [1, 4]. The presolar grain abundance among these minimally altered CP IDPs varies widely. "Isotopically primitive" IDPs distinguished by anomalous bulk N isotopic compositions, numerous 15N-rich hotspots, and some C isotopic anomalies have higher average abundances of presolar grains (375 ppm) than IDPs with isotopically normal bulk N (<10 ppm) [5]. Some D and N isotopic anomalies have been linked to carbonaceous matter, though this material is only rarely isotopically anomalous in C [1, 5, 6]. Previous studies of the bulk chemistry and, in some samples, the mineralogy of select anhydrous CP IDPs indicate a link between high C abundance and pyroxene-dominated mineralogy [7]. In this study, we conduct coordinated mineralogical and isotopic analyses of samples that were analyzed by [7] to characterize isotopically anomalous materials and to establish possible correlations with C abundance.

  15. Multiple parent bodies of ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Yomogida, K.; Matsui, T.

    1984-01-01

    Thermal histories of chondrite parent bodies are calculated from an initial state with material in a powder-like form, taking into account the effect of consolidation state on thermal conductivity. The very low thermal conductivity of the starting materials makes it possible for a small body with a radius of less than 100 km to be heated by several hundred degrees even if long-lived radioactive elements in chondritic abundances are the only source of heat. The maximum temperature is determined primarily by the temperature at which sintering of the constituent materials occurs. The thermal state of the interior of a chondrite parent body after sintering has begun is nearly isothermal. Near the surface, however, where the material is unconsolidated and the thermal conductivity is much lower, the thermal gradient is quite large. This result contradicts the conventional 'onion-shell' model of chondrite parent bodies. But because the internal temperature is almost constant through the whole body, it supports a 'multiple-parent bodies' model, according to which each petrologic type of chondrite comes from a different parent body.

  16. Exposure ages of carbonaceous chondrites, 1

    NASA Technical Reports Server (NTRS)

    Nishiizumi, K.; Arnold, J. R.; Caffee, M. W.; Finkel, R. C.; Southon, J. R.; Nagai, H.; Honda, M.; Sharma, P.; Imamura, M.; Kobayashi, K.

    1993-01-01

    The recent exposure histories of carbonaceous chondrites have been investigated using cosmogenic radionuclides. Our results may indicate a clustering of exposure ages of C1 and C2 chondrites into two peaks, 0.2 My and 0.6 My, perhaps implying two collisional events of Earth-crossing parent bodies. Among carbonaceous chondrites are some having short exposure ages which Mazor et al. hypothesized cluster into a small number of families. This hypothesis is based on spallogenic Ne-21 exposure ages, which in some instances are difficult to determine owing to the large amounts of trapped noble gases in carbonaceous chondrites. Also, since Ne-21 is stable, it integrates a sample's entire exposure history, so meteorites with complex exposure histories are difficult to understand using exclusively Ne-21. Cosmogenic radionuclides provide an alternative means of determining the recent cosmic ray exposure duration. To test the hypothesis of Mazor et al. we have begun a systematic investigation of exposure histories of Antarctic and non-Antarctic carbonaceous chondrites especially C2s.

  17. Mobile trace element contents in Jilin chondrite

    NASA Technical Reports Server (NTRS)

    Sakuragi, Y.; Lipschutz, M. E.

    1985-01-01

    A determination is conducted of ppm-ppt levels of Co, Se, Ga, Rb, Cs, Te, Bi, Ag, In, Tl, Zn and Cd (arranged empirically in order of increasing mobility at 1000 C) by radiochemical neutron activation analysis in eight Jilin samples of known Ar-40 content and a large vein from one of these. The trace element contents of the vein do not differ markedly from those of Jilin whole-rock samples. Only Rb correlates with Ar-40, possibly due to chance. All elements but Cd are present at levels similar to thdse in H4-6 chondrites with long K/Ar age (i.e., presumably mildly shocked). These levels are low relative to those in analogous L4-6 chondrites suggesting that H chondrites formed and/or evolved under higher pre-shock temperatures than did mildly shocked L chondrites. Time-temperature conditions during shock-loading of Jilin parent material were mild relative to those in strongly shocked L chondrites, being sufficient at most only to mobilize Cd.

  18. Ubiquitous brecciation after metamorphism in equilibrated ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Scott, E. R. D.; Lusby, D.; Keil, K.

    1985-01-01

    Ten objects with aberrant Fe/(Fe + Mg) ratios have been found in apparently unbrecciated types 4-6 H and L chondrites. Since the Fe/(Fe + Mg) ratios of these objects are incompatible with the metamorphic history of the host chondrites, it is concluded that a high proportion of ordinary chondrites are breccias that were lithified after peak metamorphism. This is consistent with the results of Scott (1984), who concluded that most type three ordinary chondrites are breccias of materials with diverse thermal histories, even though they do not show prominent brecciation. It is found that the classification scheme of Van Schmus and Wood (1967) does not identify chondrites with similar thermal histories; the petrologic type of a chondrite is only a measure of the average thermal history of its ingredients. Chondrite and achondrite breccias are also compared in order to understand how brecciation of chondrites after metamorphism is so well camouflaged.

  19. Magnetite in the unequilibrated CK chondrites: Implications for metamorphism and new insights into the relationship between the CV and CK chondrites

    NASA Astrophysics Data System (ADS)

    Dunn, Tasha L.; Gross, Juliane; Ivanova, Marina A.; Runyon, Simone E.; Bruck, Andrea M.

    2016-09-01

    Bulk isotopic and elemental compositions of CV and CK chondrites have led to the suggestion that both originate from the same asteroid. It has been argued that magnetite compositions also support this model; however, magnetite has been studied almost exclusively in the equilibrated (type 4-6) CKs. Magnetite in seven unequilibrated CKs analyzed here is enriched in MgO, TiO2, and Al2O3 relative to the equilibrated CKs, suggesting that magnetite compositions are affected by metamorphism. Magnetite in CKs is compositionally distinct from CVs, particularly in abundances of Cr2O3, NiO, and TiO2. Although there are minor similarities between CV and equilibrated CK chondrite magnetite, this is contrary to what we would expect if the CVs and CKs represent a single metamorphic sequence. CV magnetite should resemble CK3 magnetite, as both were metamorphosed to type 3 conditions. Oxygen fugacities and temperatures of CVox and CK chondrites are also difficult to reconcile using existing CV-CK parent body models. Mineral chemistries, which eliminate issues of bulk sample heterogeneity, provide a reliable alternative to techniques that involve a small amount of sample material. CV and CK chondrite magnetite has distinct compositional differences that cannot be explained by metamorphism.

  20. In Situ Location and Characterization of Carbon-bearing Phases in Carbonaceous Chondrites: Insights from Yamato 791198, a Weakly-altered CM2 Chondrite

    NASA Technical Reports Server (NTRS)

    Brearley, Adrian J.

    2004-01-01

    Intense studies of carbonaceous chondrites have provided remarkable insights into the behavior of carbon during the earliest stages of our solar system. This research has demonstrated that carbonaceous meteorites contain a diverse array of organic compounds, whose origins are probably the result of multiple processes that occurred in different locations including interstellar space, the solar nebula and asteroidal parent bodies [1-3]. The most abundant organic carbon component in CI1 and CM2 carbonaceous chondrites is so-called macromolecular carbon, a high molecular weight material that has some affinities to terrestrial kerogen and constitutes approximately 60-70% of the organic material in these meteorites. Although recent studies e.g. [3] have radically improved our understanding of the structural and compositional characteristics of this material, a number of key questions remain to be addressed. In particular, our knowledge of where this macromolecular material is distributed at the fine-scale within carbonaceous chondrites is scant. [4] have shown that organic material is associated with phyllosilicate-rich matrix in CM chondrites, but the detailed mineralogical associations are not well-known. Over the past 2 years, we have begun to address this question by using energy filtered transmission electron microscopy (EFTEM) to locate carbon-bearing materials in situ, focusing specifically on the CM2s. To date we have reported data on the Murchison CM2 chondrite [5], a meteorite that has experienced a modest degree of aqueous alteration. To extend our observations to other CM2 chondrites, we have examined the occurrence of carbon-bearing phases in Yamato 791198. Our recent studies [5] have shown that Y-791198 is among the most weakly-altered CM chondrite currently known and hence is likely to preserve a quite primitive distribution of carbonaceous material. In this study, we present initial observations on the distribution of these materials in one fine

  1. On the origin of Sérsic profiles of galaxies and Einasto profiles of dark-matter halos

    NASA Astrophysics Data System (ADS)

    Nipoti, Carlo

    2017-03-01

    The surface-brightness profiles of galaxies I(R) and the density profiles of dark-matter halos ρ(r) are well represented by the same analytic function, named after either Sérsic, I~e -(R/R *)1/m , or Einasto, ρ~e -(r/r *)α , where R * and r * are characteristic radii. Systems with high Sérsic index m (or low Einasto index α) have steep central profiles and shallow outer profiles, while systems with low m (or high α) have shallow central profiles and steep profiles in the outskirts. We present the results of idealized numerical experiments which suggest that the origin of these profiles can be traced back to the initial density fluctuation field: high-α (low-m) systems form in smooth regions via few mergers, while low-α (high-m) systems form in clumpy regions via several mergers.

  2. A Survey of Large Silicate Objects in Ordinary Chondrites

    NASA Astrophysics Data System (ADS)

    Hutchison, R.; Bridges, J. C.

    1995-09-01

    We present the results of a survey of large silicate objects in ordinary chondrites (OCs) from the collection of the Natural History Museum, London; 390 H-group, 386 L-group and 57 LL-group meteorites were examined. A total of 61 objects were identified (Table 1). Meteorites with light and dark, brecciated fabrics were excluded from our survey. Following Weisberg et al. [1], large silicate objects are taken to be >= 5mm in size. Macrochondrules have rounded outlines and textures - porphyritic, barred olivine, radiating pyroxene - that are indistinguishable from normal chondrules in OCs [1]. In addition, we also recognise igneous clasts and chondritic clasts. The largest macrochondrule in the collection is 4cm diameter, with a microporphyritic texture [2]. Igneous clasts are those objects whose properties indicate that they originated through melting and differentiation on a planetary body. Examples include a 2cm diameter clast, in Ness County (L6), which contains large (2mm) olivine and enstatite grains set in a plagioclase + olivine groundmass, cristobalite- and tridymite-rich clasts [3] and the FELINE feldspar-nepheline clast [4]. Chondritic clasts comprise a diverse group including a 1cm clast from Barwell (L6) which contains apparently remelted chondrules, microporphyritic clasts with K-rich mesostasis e.g. in Quenggouk (H4) and a 1cm single olivine grain with minor inclusions of anorthite and enstatite, in Julesburg (L3). The K-rich objects are similar to others described from a survey of LL-chondrites and may have an impact origin or have undergone exchange with a K-rich vapor [5]. Abundances of the three types of large silicate objects (Table 1) reflect the relative numbers of H, L and LL meteorite samples in the collection, although LL-group hosted clasts are over-represented as our work concentrated on sections of LL-chondrites. In total, 46% of the objects are macrochondrules, 18% are igneous clasts and 36% are in the indeterminate chondritic clast group

  3. Educational achievement of immigrant adolescents in Spain: do gender and region of origin matter?

    PubMed

    Vaquera, Elizabeth; Kao, Grace

    2012-01-01

    This study explores the educational achievement of immigrant youth in Spain employing data from 3 waves of the Longitudinal Study of Families and Childhood (Pànel de Famílies i Infància), a representative sample of children in Catalonia first interviewed at ages 13-16 in 2006 (N = 2,710). Results suggest consistent disadvantage in achievement among first-generation students. Differences in achievement between the second and third generations are apparent in bivariate analyses, but are explained by observable characteristics in multivariate analyses. Gender-specific analyses uncover a large achievement gap between first-generation girls and their third-generation counterparts, but no equivalent gap for boys. Region-of-origin differences are modest, with the exception of Latin American adolescents who exhibit the lowest educational outcomes. The significance of perceptions about school on achievement are discussed. © 2012 The Authors. Child Development © 2012 Society for Research in Child Development, Inc.

  4. The Origin of Invasive Microorganisms Matters for Science, Policy, and Management: The Case of Didymosphenia geminata

    PubMed Central

    Taylor, Brad W.; Bothwell, Max L.

    2014-01-01

    The value of distinguishing native from nonnative invasive species has recently been questioned. However, this dichotomy is important for understanding whether a species’ successful dominance is caused by introductions, changing environmental conditions that facilitate an existing population, or both processes. We highlight the importance of knowing the origin of hard-to-detect invasive microorganisms for scientific research, management, and policy using a case study of recent algal blooms of the stalk-producing diatom Didymosphenia geminata. Nuisance blooms have been reported in rivers worldwide and have been hastily attributed to introductions. However, evidence indicates that blooms are probably not caused by introductions but, rather, by environmental conditions that promote excessive stalk production by this historically rare species. Effective responses to invasive microorganisms depend on knowing whether their proliferation is caused by being nonnative or is the result of changing environmental conditions that promote invasive characteristics of native species. PMID:26955071

  5. Origins, seasonality, and fluxes of organic matter in the Congo River

    NASA Astrophysics Data System (ADS)

    Spencer, Robert G. M.; Hernes, Peter J.; Dinga, Bienvenu; Wabakanghanzi, Jose N.; Drake, Travis W.; Six, Johan

    2016-07-01

    The Congo River in central Africa represents a major source of organic matter (OM) to the Atlantic Ocean. This study examined elemental (%OC, %N, and C:N), stable isotopic (δ13C and δ15N), and biomarker composition (lignin phenols) of particulate OM (POM) and dissolved OM (DOM) across the seasonal hydrograph. Even though the Congo exhibits an extremely stable intra-annual discharge regime, seasonal variability in OM composition was evident. DOM appears predominantly derived from vascular plant inputs with greater relative contribution during the rising limb and peak in discharge associated with the major November-December discharge maximum. Generally, POM appears to be sourced from soil-derived mineral-associated OM (low C:N, low Λ8, and higher (Ad:Al)v) but the relative proportion of fresh vascular plant material (higher C:N, higher Λ8, and lower (Ad:Al)v) increases with higher discharge. During the study period (September 2009 to November 2010) the Congo exported 29.21 Tg yr-1 of total suspended sediment (TSS), 1.96 Tg yr-1 of particulate organic carbon (POC), and 12.48 Tg yr-1 of dissolved organic carbon. The Congo exports an order of magnitude lower TSS load in comparison to other major riverine sources of TSS (e.g., Ganges and Brahmaputra), but due to its OM-rich character it actually exports a comparable amount of POC. The Congo is also 2.5 times more efficient at exporting dissolved lignin per unit volume compared to the Amazon. Including Congo dissolved lignin data in residence time calculations for lignin in the Atlantic Ocean results in an approximately 10% reduction from the existing estimate, suggesting that this material is more reactive than previously thought.

  6. Origin of matter and space-time in the big bang

    NASA Astrophysics Data System (ADS)

    Mathews, G. J.; Kajino, T.; Yamazaki, D.; Kusakabe, M.; Cheoun, M.-K.

    2014-05-01

    We review the case for and against a bulk cosmic motion resulting from the quantum entanglement of our universe with the multiverse beyond our horizon. Within the current theory for the selection of the initial state of the universe from the landscape multiverse there is a generic prediction that pre-inflation quantum entanglement with other universes should give rise to a cosmic bulk flow with a correlation length of order horizon size and a velocity field relative to the expansion frame of the universe. Indeed, the parameters of this motion are are tightly constrained. A robust prediction can be deduced indicating that there should be an overall motion of of about 800 km/s relative to the background space time as defined by the cosmic microwave background (CMB). This talk will summarize the underlying theoretical motivation for this hypothesis. Of course our motion relative to the background space time (CMB dipole) has been known for decades and is generally attributed to the gravitational pull of the local super cluster. However, this cosmic peculiar velocity field has been recently deduced out to very large distances well beyond that of the local super cluster by using X-ray galaxy clusters as tracers of matter motion. This is achieved via the kinematic component of the Sunyaev-Zeldovich (KSZ) effect produced by Compton scattering of cosmic microwave background photons from the local hot intracluster gas. As such, this method measures peculiar velocity directly in the frame of the cluster. Similar attempts by our group and others have attempted to independently assess this bulk flow via Type la supernova redshifts. In this talk we will review the observation case for and against the existence of this bulk flow based upon the observations and predictions of the theory. If this interpretation is correct it has profound implications in that we may be observing for the first time both the physics that occurred before the big bang and the existence of the multiverse

  7. Origin of matter and space-time in the big bang

    SciTech Connect

    Mathews, G. J.; Yamazaki, D.; Kusakabe, M.; Cheoun, M.-K.

    2014-05-02

    We review the case for and against a bulk cosmic motion resulting from the quantum entanglement of our universe with the multiverse beyond our horizon. Within the current theory for the selection of the initial state of the universe from the landscape multiverse there is a generic prediction that pre-inflation quantum entanglement with other universes should give rise to a cosmic bulk flow with a correlation length of order horizon size and a velocity field relative to the expansion frame of the universe. Indeed, the parameters of this motion are are tightly constrained. A robust prediction can be deduced indicating that there should be an overall motion of of about 800 km/s relative to the background space time as defined by the cosmic microwave background (CMB). This talk will summarize the underlying theoretical motivation for this hypothesis. Of course our motion relative to the background space time (CMB dipole) has been known for decades and is generally attributed to the gravitational pull of the local super cluster. However, this cosmic peculiar velocity field has been recently deduced out to very large distances well beyond that of the local super cluster by using X-ray galaxy clusters as tracers of matter motion. This is achieved via the kinematic component of the Sunyaev-Zeldovich (KSZ) effect produced by Compton scattering of cosmic microwave background photons from the local hot intracluster gas. As such, this method measures peculiar velocity directly in the frame of the cluster. Similar attempts by our group and others have attempted to independently assess this bulk flow via Type la supernova redshifts. In this talk we will review the observation case for and against the existence of this bulk flow based upon the observations and predictions of the theory. If this interpretation is correct it has profound implications in that we may be observing for the first time both the physics that occurred before the big bang and the existence of the multiverse

  8. On the origin of individual functional connectivity variability: The role of white matter architecture.

    PubMed

    Chamberland, Maxime; Girard, Gabriel; Bernier, Michael; Fortin, David; Descoteaux, Maxime; Whittingstall, Kevin

    2017-08-21

    Fingerprint patterns derived from functional connectivity (FC) can be used to identify subjects across groups and sessions, indicating that the topology of the brain substantially differs between individuals. Yet, the source of FC variability inferred from resting-state functional MRI (rs-fMRI) remains unclear. One possibility is that these variations are related to individual differences in white matter structural connectivity (SC). However, directly comparing FC to SC is challenging given the many potential biases associated with quantifying their respective strengths. In an attempt to circumvent this, we employed a recently proposed test-retest approach that better quantifies inter-subject variability by first correcting for intra-subject nuisance variability (i.e. head motion, physiological differences in brain state, etc.) which can artificially influence FC and SC measures. Therefore, rather than directly comparing the strength of FC to SC, we asked whether brain regions with, for example, low inter-subject FC variability also exhibited low SC variability. From this, we report two main findings: First, at the whole-brain level, SC variability was significantly lower than FC variability, indicating that an individual's structural connectome is far more similar to another relative to their functional counterpart even after correcting for noise. Second, while FC and SC variability were mutually low in some brain areas (e.g. primary somatosensory cortex) and high in others (e.g. memory and language areas), the two were not significantly correlated across all cortical and sub-cortical regions. Taken together, these results indicate that even after correcting for factors which may differently affect FC and SC, the two nonetheless remain largely independent of one another. Further work is needed to understand the role direct anatomical pathways play in supporting vascular-based measures of FC and to what extent these measures are dictated by anatomical connectivity.

  9. Origin-Oriented Elemental Profile of Fine Ambient Particulate Matter in Central European Suburban Conditions

    PubMed Central

    Rogula-Kozłowska, Wioletta; Majewski, Grzegorz; Błaszczak, Barbara; Klejnowski, Krzysztof; Rogula-Kopiec, Patrycja

    2016-01-01

    Twenty-four-hour samples of fine ambient particulate matter (PM2.5; particles with aerodynamic diameters ≤2.5 µm) were collected in a suburban (quasi-rural) area in Racibórz (Poland) between 1 January 2011 and 26 December 2012. The samples were analyzed for the contents of 28 elements. Sources of PM2.5 were identified and the contribution of each source to the PM2.5 concentration was assessed using an enrichment factor (EF) analysis, a principal component analysis (PCA), and multi-linear regression analysis (MLRA). In the cold season (January–March and October–December 2011–2012), the mean ambient concentration of PM2.5 in Racibórz was 48.7 ± 39.4 µg·m−3, which was much higher than at other suburban or rural sites in Europe. Additionally the ambient concentrations of some toxic PM2.5-bound elements were also high, i.e., the mean ambient concentrations of PM2.5-bound As, Cd, and Pb were 11.3 ± 11.5, 5.2 ± 2.5, and 34.0 ± 34.2 ng·m−3, respectively. In the warm season (April–September 2011–2012), the PM2.5 and PM2.5-bound element concentrations in Racibórz were comparable to the concentrations noted at other suburban (or rural) sites in Europe. Our findings suggest that elemental composition and concentrations of PM2.5 in Racibórz are mainly influenced by anthropogenic emissions, i.e., the energy production based on coal and biomass combustion, traffic, and industry. PMID:27428988

  10. Summary of several recent chondrite finds from the Texas Panhandle

    NASA Astrophysics Data System (ADS)

    Sipiera, S. P.; Olsen, E. J.; Eatough, D. L.; Dod, B. D.

    1983-03-01

    Eleven recent chondrite finds from the Texas Panhandle have been examined and classified according to mineralogical and petrological criteria: five H's, five L's, and one LL chondrite. Five are distinct from nearby finds, while three remain ambiguous and three are related to previously reported chondrites. In addition, data are provided to classify the Muleshoe, Silverton, and Vigo Park chondrites, all of which were previously undescribed in the literature.

  11. Summary of several recent chondrite finds from the Texas Panhandle

    NASA Technical Reports Server (NTRS)

    Sipiera, P. S.; Olsen, E. J.; Eatough, D. L.; Dod, B. D.

    1983-01-01

    Eleven recent chondrite finds from the Texas Panhandle have been examined and classified according to mineralogical and petrological criteria: five H's, five L's, and one LL chondrite. Five are distinct from nearby finds, while three remain ambiguous and three are related to previously reported chondrites. In addition, data are provided to classify the Muleshoe, Silverton, and Vigo Park chondrites, all of which were previously undescribed in the literature.

  12. The accretion and impact history of the ordinary chondrite parent bodies

    NASA Astrophysics Data System (ADS)

    Blackburn, Terrence; Alexander, Conel M. O'D.; Carlson, Richard; Elkins-Tanton, Linda T.

    2017-03-01

    A working timeline for the history of ordinary chondrites includes chondrule formation as early as 0-2 Ma after our Solar System's earliest forming solids (CAIs), followed by rapid accretion into undifferentiated planetesimals that were heated internally by 26Al decay and cooled over a period of tens of millions of years. There remains conflict, however, between metallographic cooling rate (Ni-metal) and radioisotopic thermochronometric data over the sizes and lifetimes of the chondrite parent bodies, as well as the timing of impact related disruptions. The importance of establishing the timing of parent body disruption is heightened by the use of meteorites as recorders of asteroid belt wide disruption events and their use to interpret Solar System dynamical models. Here we attempt to resolve these records by contributing new 207Pb-206Pb data obtained on phosphates isolated from nine previously unstudied ordinary chondrites. These new results, along with previously published Pb-phosphate, Ni-metal and thermometry data, are interpreted with a series of numerical models designed to simulate the thermal evolution for a chondrite parent body that either remains intact or is disrupted by impact prior to forming smaller unsorted "rubble piles". Our thermal model and previously published thermometry data limit accretion time to 2.05-2.25 Ma after CAIs. Measured Pb-phosphate data place minimum estimates on parent body diameters of ∼260-280 km for both the L and H chondrite parent bodies. They also consistently show that petrologic Type 6 (highest thermal metamorphism) chondrites from both the H and L bodies have younger ages and, therefore, cooled more slowly than Type 5 (lesser metamorphism) chondrites. This is interpreted as evidence for Type 5 chondrite origination from shallower depths than Type 6 chondrites within initially concentrically zoned bodies. This contrasts metallographic cooling rate data that are inconsistent with such a simple onion shell scenario. One

  13. Early planetary metamorphism in chondritic meteorites

    NASA Astrophysics Data System (ADS)

    Hanan, B. B.; Tilton, G. R.

    1985-07-01

    The record of early events in the solar system is presently sought, together with information on the isotopic composition of primordial lead, in the lead isotope relations of whole rock and separated phases of Mezo-Madaras (L3) and Sharps (H3) chondrites; the respective ages of 4.48 and 4.47 billion years are not significantly changed when Canyon Diablo troilite lead is included in the data sets, suggesting that the initial Pb isotopic composition in both meteorites was the same as that in the troilite. The 4.48 billion year age, which is younger than the well established 4.54-4.56 billion years of the Allende chondrite and Angra dos Reis achondrite, appears to date an early metamorphic event rather than the formation of the chondrites.

  14. Experimental vaporization of the Holbrook chondrite

    NASA Technical Reports Server (NTRS)

    Gooding, J. L.; Muenow, D. W.

    1977-01-01

    The vapor phase composition obtained by heating samples of the Holbrook L6 chondrite to 1300 C was determined quantitatively by Knudsen cell-quadrupole mass spectrometry. Maximum observed vapor pressures, produced at 1200 C, are reported for Na, K, Fe, and Ni, and the implications of the Na/K ratio are considered. The Fe and Ni data are discussed with attention to their migration in individual equilibrated chondrites. S2 (with minor SO2), H2O, and CO2 were also present in the high-temperature gas phase. Vesicles formed by the release of intrinsically derived volatiles are compared with vesicles in the Ibitira eucrite. Chondrite evolution is briefly discussed.

  15. An H chondrite stream - Identification and confirmation

    NASA Technical Reports Server (NTRS)

    Dodd, Robert T.; Wolf, Stephen F.; Lipschutz, Michael E.

    1993-01-01

    Fall data indicate that a significant, elongate cluster of co-orbital H chondrite falls in May between 1855 and 1895 (H Cluster 1) records encounters with two or three closely spaced and probably related meteoroid stream components, each of which was met near its perihelion. Although meteorites included in the cluster vary widely in petrographic type, shock facies, and Ne-21 exposure age, they have a distinct labile trace element signature that confirms a common thermal history and, thus, a common source region within an H chondrite parent body. Hence, meteorites selected by one criterion (fall parameters) as distinguishable from all other H chondrites, are distinguished from them by another completely different criterion (contents of labile trace elements).

  16. Highly Porous and Compositionally Intermediate Ordinary Chondrite LAP 031047

    NASA Astrophysics Data System (ADS)

    Wittmann, A.; Kring, D. A.; Friedrich, J. M.; Troiano, J.; Macke, R. J.; Britt, D. T.; Swindle, T. D.; Weirich, J. R.; Rumble, D.

    2010-03-01

    LAP 031047 is a highly porous ordinary chondrite with a very young Ar-Ar age, and oxygen isotopic, and bulk and silicate mineral composition intermediate between H- and L-chondrites: Shock-lithified debris of a distinct ordinary chondrite asteroid?

  17. First known EL5 chondrite - Evidence for dual genetic sequence for enstatite chondrites

    NASA Technical Reports Server (NTRS)

    Sears, D. W. G.; Weeks, K. S.; Rubin, A. E.

    1984-01-01

    The compositionally distinct EH and EL groups together with four (3-6) petrologic types which constitute the enstatite chondrites represent increasing degrees of metamorphic alteration. Although bulk composition variations preclude a simple conversion of EH4 into EL6 material, complex models which involve simultaneous bulk composition and petrologic type variations may be implied by other classification schemes in common use. Attention is presently given to the discovery of the first EL5 chondrite, which breaks the EH3,4-EH5-EL6 sequence and indicates that the enstatite chondrites constitute the two discrete, isochemical metamorphic sequences EH3-5 and EL5-6.

  18. Does the Data Resolution/origin Matter? Satellite, Airborne and Uav Imagery to Tackle Plant Invasions

    NASA Astrophysics Data System (ADS)

    Müllerová, Jana; Brůna, Josef; Dvořák, Petr; Bartaloš, Tomáš; Vítková, Michaela

    2016-06-01

    Invasive plant species represent a serious threat to biodiversity and landscape as well as human health and socio-economy. To successfully fight plant invasions, new methods enabling fast and efficient monitoring, such as remote sensing, are needed. In an ongoing project, optical remote sensing (RS) data of different origin (satellite, aerial and UAV), spectral (panchromatic, multispectral and color), spatial (very high to medium) and temporal resolution, and various technical approaches (object-, pixelbased and combined) are tested to choose the best strategies for monitoring of four invasive plant species (giant hogweed, black locust, tree of heaven and exotic knotweeds). In our study, we address trade-offs between spectral, spatial and temporal resolutions required for balance between the precision of detection and economic feasibility. For the best results, it is necessary to choose best combination of spatial and spectral resolution and phenological stage of the plant in focus. For species forming distinct inflorescences such as giant hogweed iterative semi-automated object-oriented approach was successfully applied even for low spectral resolution data (if pixel size was sufficient) whereas for lower spatial resolution satellite imagery or less distinct species with complicated architecture such as knotweed, combination of pixel and object based approaches was used. High accuracies achieved for very high resolution data indicate the possible application of described methodology for monitoring invasions and their long-term dynamics elsewhere, making management measures comparably precise, fast and efficient. This knowledge serves as a basis for prediction, monitoring and prioritization of management targets.

  19. Drinks per day in women of Mexican origin: does birth place matter?

    PubMed

    Hardie, Thomas L; Polek, Carolee; Garcia, Victor; González, Laura; Welsh, Marcia

    2013-01-01

    Historically, Mexican-born women who immigrate to the United States (U.S.) have lower levels of alcohol use and higher rates of abstinence compared with Mexican American women born in the U.S. and other racial groups in the U.S. As such, immigrant women's alcohol use has received limited attention by the research community. Gaps in knowledge of their alcohol use patterns, changes in healthy drinking recommendation for women, and projections of population growth in both Mexican immigrant and Mexican American populations support the need for the study. Data from the Center for Disease Control's National Health Interview Survey were used to explore alcohol use differences in women of Mexican origin born in and outside of the U.S. In addition, the relationship between years in the U.S. and drinks per day was explored in Mexican immigrant women. The results indicated that Mexican immigrant women who drink are drinking above recommended levels and the younger immigrant women are drinking more drinks per day than young Mexican American women. These changes point to the importance of developing culturally sensitive interventions for this expanding segment of the population.

  20. The Carlisle Lakes-type chondrites: A new grouplet with high. Delta. sup 17 O and evidence for nebular oxidation

    SciTech Connect

    Weisberg, M.K. Brooklyn Coll., NY ); Prinz, M. ); Kojima, Hideyasu; Yanai, Keizo ); Clayton, R.N.; Mayeda, T.K. )

    1991-09-01

    Carlisle Lakes, ALH85151, and Y75302 are similar ungrouped chondrites which have petrologic and bulk compositional similarities to the ordinary chondrites, but are more oxidized; and their oxygen isotopic compositions differ. They represent a new grouplet which the authors call the Carlisle Lakes-type chondrites. They have the highest {Delta}{sup 17}O values (up to 2.91) measured to date. The whole chondrites and most of their chondrules plot on the same mass fractionation line on an oxygen 3-isotope diagram. They are olivine rich (>70 vol%), essentially metal free, and most olivine is FeO rich, equilibrated at Fa{sub 38}. Rare olivine and pyroxene grains in chondrules and fragments are zoned, and these are important in discerning the history of these chondrites. The zoning does not appear to have formed during crystallization from a melt droplet chondrule, but post-dated chondrule formation. Two hypotheses are postulated to explain the zoning: (1) parent-body thermal metamorphism and (2) nebular gas-solid exchange reactions accompanied by condensation of new FeO-rich olivine, utilizing existing olivine surfaces as nucleation sites. The occurrence of steep Fe-Mg compositional gradients of core-to-rim profiles, oscillatory zoning in olivine, fayalitic rims of Fa{sub 45} that exceed instead of approach the equilibrium composition of the matrix (Fa{sub 38}), and olivine-filled veins in zoned pyroxenes are more compatible with the nebular hypothesis. The Carlisle Lakes-type chondrites may have originally been derived from an ordinary chondrite-like precursor which was later oxidized, prior to its final lithification. However, the oxygen isotopic compositions of the whole chondrites and most of their chondrules suggest that the precursor probably formed in an oxygen isotopically distinct environment.

  1. Silver isotope variations in chondrites: Volatile depletion and the initial 107Pd abundance of the solar system

    NASA Astrophysics Data System (ADS)

    Schönbächler, M.; Carlson, R. W.; Horan, M. F.; Mock, T. D.; Hauri, E. H.

    2008-11-01

    The extinct radionuclide 107Pd decays to 107Ag (half-life of 6.5 Ma) and is an early solar system chronometer with outstanding potential to study volatile depletion in the early solar system. Here, a comprehensive Ag isotope study of carbonaceous and ordinary chondrites is presented. Carbonaceous chondrites show limited variations ( ɛ107Ag = -2.1 to +0.8) in Ag isotopic composition that correlate with the Pd/Ag ratios. Assuming a strictly radiogenic origin of these variations, a new initial 107Pd/ 108Pd of 5.9 (±2.2) × 10 -5 for the solar system can be deduced. Comparing the Pd-Ag and Mn-Cr data for carbonaceous chondrites suggests that Mn-Cr and Pd-Ag fractionation took place close to the time of calcium-aluminium-rich inclusion (CAI) and chondrule formation ˜4568 Ma ago. Using the new value for the initial 107Pd abundance, the revised ages for the iron-rich meteorites Gibeon (IVA, 8.5 +3.2/-4.6 Ma), Grant (IIIAB, 13.0 +3.5/-4.9 Ma) and Canyon Diablo (IA, 19.5 +24.1/-10.4 Ma) are consistent with cooling rates and the closure temperature of the Pd-Ag system. In contrast to carbonaceous chondrites, ordinary chondrites show large stable isotope fractionation of order of 1 permil for 107Ag/ 109Ag. This indicates that different mechanisms of volatile depletion were active in carbonaceous and ordinary chondrites. Nebular processes and accretion, as experienced by carbonaceous chondrites, did not led to significant Ag isotope fractionation, while the significant Ag isotope variations in ordinary chondrites are most likely inflicted by open system parent body metamorphism.

  2. Sm-Nd systematics of chondrites

    NASA Astrophysics Data System (ADS)

    Amelin, Yuri; Rotenberg, Ethan

    2004-07-01

    We have studied the 147Sm- 143Nd and 146Sm- 142Nd isotopic systems in phosphate fractions and chondrules from six ordinary chondrites and one carbonaceous chondrite, previously dated with Pb-Pb method. 147Sm/ 144Nd ratios vary between 0.182 and 0.191 in phosphates, and between 0.179 and 0.243 in chondrules. The 147Sm- 143Nd isochron regression through all 34 phosphate and chondrule analyses yields a date of 4588±100 Ma and is in good agreement with more precise Pb-Pb dates of the same chondrites. The initial 143Nd/ 144Nd is 0.50665±0.00014. The same analyses define a 146Sm- 142Nd isochron with a slope corresponding to 146Sm/ 144Sm=0.0075±0.0027. Initial 142Nd/ 144Nd=1.14160±0.00011 corresponds to ɛ142Nd=-2.62±0.93. Compilation of the published chondritic whole rock Sm-Nd analyses yields the median 147Sm/ 144Nd=0.1964+0.0003/-0.0007, which is our preferred Chondritic Uniform Reservoir (CHUR) value. Using this value and its error limits, we find the present-day CHUR 143Nd/ 144Nd=0.512637+0.000009/-0.000021 from the chondritic Sm-Nd isochron that includes all available data for whole rocks, chondrules and phosphates. This value is identical within error with the currently accepted number. An estimate of the bulk earth 147Sm/ 144Nd=0.1941±0.0059 is obtained from intercept of chondritic 146Sm- 142Nd isochron with the terrestrial value of 142Nd/ 144Nd. This estimate is independent of measured Sm/Nd ratios in chondrites. The same approach was applied to published 146Sm- 142Nd internal isochrons for differentiated meteorites and yielded similar, although less precise, values. Our data are completely consistent with the currently accepted CHUR parameters and substantiate their use as terrestrial reference values.

  3. Mineralogy of chondritic interplanetary dust particles

    NASA Astrophysics Data System (ADS)

    MacKinnon, I. D. R.; Rietmeijer, F. J. M.

    1987-08-01

    This paper presents a synopsis of current investigations on the mineralogy of chondritic micrometeorites obtained from the lower stratosphere using flat-plate collection surfaces attached to high-flying aircraft. A compilation of detailed mineralogical analyses for 30 documented chondritic interplanetary dust particles indicates a wide variety of minerals present in assemblages which, as yet, are poorly defined. Two possible assemblages are: (1) carbonaceous phases and layer silicates and (2) carbonaceous and chain silicates or nesosilicates. Particles with both types of silicate assemblages are also observed.

  4. Micro-Scale Distributions of Major and Trace Elements in Chondrites

    NASA Technical Reports Server (NTRS)

    Ireland, T. R.; Zolensky, M.

    2011-01-01

    The Hayabusa spacecraft has successfully returned to Earth after two touchdowns on the surface of Asteroid 25143 Itokawa. This asteroid is classified as an S-type and inferred to consist of materials similar to ordinary chondrites or primitive achondrites [1]. More than 1500 particles have been identified consisting of olivine, pyroxene, plagioclase, Fe sulfide and Fe metal, with compositions consistent with being of LL origin. While the chondritic components are familiar to us, the level of detail to which the Itokawa samples will be exposed to will be unprecedented given that the samples are reasonably large and accessible to a wide variety of techniques. In many ways, we expect that our knowledge base of the comparator chondrites will be found to be wanting. Chondrites are the building blocks of the solar system. However, these rocks are essentially breccias and they are quite variable in bulk element compositions as well as compositions of the individual components. We have initiated a program of analysis for chondrites focusing on major and trace element distributions between the mineral components and the matrix. The issues to be addressed include the homogeneity of matrix and chondrule components and the representivity of any given sample to the bulk meteorite. This may be particularly important given the limited numbers of Itokawa grains that may be available for a specific analysis. As an initial study, we have taken thin sections of carbonaceous chondrites to study the representivity of the matrix compositions. Spot locations were constrained to limited regions of the sections so as to assess the variability of a local scale. Further work will be required to assess variability over a centimeter scale.

  5. Oxygen Isotope Systematics of Chondrules from the Least Equilibrated H Chondrite

    NASA Technical Reports Server (NTRS)

    Kita, N. T.; Kimura, M.; Ushikubo, T.; Valley, J. W.; Nyquist, L. E.

    2008-01-01

    Oxygen isotope compositions of bulk chondrules and their mineral separates in type 3 ordinary chondrites (UOC) show several % variability in the oxygen three isotope diagram with slope of approx.0.7 [1]. In contrast, ion microprobe analyses of olivine and pyroxene phenocrysts in ferromagnesian chondrules from LL 3.0-3.1 chondrites show mass dependent isotopic fractionation as large as 5% among type I (FeO-poor) chondrules, while type II (FeO-rich) chondrules show a narrow range (less than or equal to 1%) of compositions [2]. The .Delta(exp 17)O (=delta(exp 17)O-0.52xdelta(exp 18)O) values of olivine and pyroxene in these chondrules show a peak at approx.0.7% that are systematically lower than those of bulk chondrule analyses as well as the bulk LL chondrites [2]. Further analyses of glass in Semarkona chondrules show .17O values as high as +5% with highly fractionated d18O (max +18%), implying O-16-poor glass in chondrules were altered as a result of hydration in the parent body at low temperature [3]. Thus, chondrules in LL3.0-3.1 chondrites do not provide any direct evidence of oxygen isotope exchange between solid precursor and O-16-depleted gas during chondrule melting events. To compare the difference and/or similarity between chondrules from LL and H chondrites, we initiated systematic investigations of oxygen isotopes in chondrules from Yamato 793408 (H3.2), one of the least equilibrated H chondrite [4]. In our preliminary study of 4 chondrules, we reported distinct oxygen isotope ratios from dusty olivine and refractory forsterite (RF) grains compared to their host chondrules and confirmed their relict origins [5].

  6. Spatial and temporal variability of marine-origin matter along a transect from Zhongshan Station to Dome A, Eastern Antarctica.

    PubMed

    Li, Chuanjin; Xiao, Cunde; Shi, Guitao; Ding, Minghu; Qin, Dahe; Ren, Jiawen

    2016-08-01

    The spatiotemporal distribution pattern of marine-origin matter on the Antarctica ice sheet was used to study variations in the source regions, transport mechanisms and post-depositional influences. We present data on sea salt ions, sulfur components and stable isotopes from surface and snow pit samples collected along the transect route from Zhongshan Station to Dome A during the austral summer in 2012-2013. A general decreasing trend in the accumulation, sea salt ions and sulfur components occurred with increasing distance from the coast and increasing elevation. However, different sources of the marine components, transport pathways and post-depositional influences were responsible for their different spatial distribution patterns. The marine ions in the coastal snow pit varied seasonally, with higher sea salt ion concentrations in the winter and lower concentrations in the summer; the opposite pattern was found for the sulfur compounds. The sea ice area surrounding Antarctica was the main source region for the deposited sea salt and the open sea water for the sulfur compounds. No significant trends in the marine-origin components were detected during the past 3 decades. Several periods of elevated deposition of sea salt ions were associated with lower temperatures (based on δD and δ(18)O) or intensified wind fields. In comparison to the sea salt ions, the sulfur concentrations exhibited the opposite distribution patterns and were associated with changes in the surrounding sea ice extent.

  7. Domesticated animals and human infectious diseases of zoonotic origins: domestication time matters.

    PubMed

    Morand, Serge; McIntyre, K Marie; Baylis, Matthew

    2014-06-01

    The rate of emergence for emerging infectious diseases has increased dramatically over the last century, and research findings have implicated wildlife as an importance source of novel pathogens. However, the role played by domestic animals as amplifiers of pathogens emerging from the wild could also be significant, influencing the human infectious disease transmission cycle. The impact of domestic hosts on human disease emergence should therefore be ascertained. Here, using three independent datasets we showed positive relationships between the time since domestication of the major domesticated mammals and the total number of parasites or infectious diseases they shared with humans. We used network analysis, to better visualize the overall interactions between humans and domestic animals (and amongst animals) and estimate which hosts are potential sources of parasites/pathogens for humans (and for all other hosts) by investigating the network architecture. We used centrality, a measure of the connection amongst each host species (humans and domestic animals) in the network, through the sharing of parasites/pathogens, where a central host (i.e. high value of centrality) is the one that is infected by many parasites/pathogens that infect many other hosts in the network. We showed that domesticated hosts that were associated a long time ago with humans are also the central ones in the network and those that favor parasites/pathogens transmission not only to humans but also to all other domesticated animals. These results urge further investigation of the diversity and origin of the infectious diseases of domesticated animals in their domestication centres and the dispersal routes associated with human activities. Such work may help us to better understand how domesticated animals have bridged the epidemiological gap between humans and wildlife.

  8. Immigration and the health of U.S. black adults: does country of origin matter?

    PubMed

    Hamilton, Tod G; Hummer, Robert A

    2011-11-01

    Previous work suggests that regional variation in pre-migration exposure to racism and discrimination, measured by a region's racial composition, predicts differences in individual-level health among black immigrants to the United States. We exploit data on both region and country of birth for black immigrants in the United States and methodology that allows for the identification of arrival cohorts to test whether there are sending country differences in the health of black adults in the United States that support this proposition. While testing this hypothesis, we also document heterogeneity in health across arrival cohorts and by duration of U.S. residence among black immigrants. Using data on working-age immigrant and U.S.-born blacks taken from the 1996-2010 waves of the March Current Population Survey, we show that relative to U.S.-born black adults, black immigrants report significantly lower odds of fair/poor health. After controlling for relevant social and demographic characteristics, immigrants' cohort of arrival, and immigrants' duration in the United States, our models show only modest differences in health between African immigrants and black immigrants who migrate from the other major sending countries or regions. Results also show that African immigrants maintain their health advantage over U.S.-born black adults after more than 20 years in the United States. In contrast, black immigrants from the Caribbean who have been in the United States for more than 20 years appear to experience some downward health assimilation. In conclusion, after accounting for relevant factors, we find that there are only modest differences in black immigrant health across countries of origin. Black immigrants appear to be very highly selected in terms of good health, although there are some indications of negative health assimilation for black immigrants from the Caribbean.

  9. Terrestrial microbes in martian and chondritic meteorites

    NASA Astrophysics Data System (ADS)

    Airieau, S.; Picenco, Y.; Andersen, G.

    2007-08-01

    Introduction: The best extraterrestrial analogs for microbiology are meteorites. The chemistry and mineralogy of Asteroid Belt and martian (SNC) meteorites are used as tracers of processes that took place in the early solar system. Meteoritic falls, in particular those of carbonaceous chondrites, are regarded as pristine samples of planetesimal evolution as these rocks are primitive and mostly unprocessed since the formation of the solar system 4.56 billion years ago. Yet, questions about terrestrial contamination and its effects on the meteoritic isotopic, chemical and mineral characteristics often arise. Meteorites are hosts to biological activity as soon as they are in contact with the terrestrial biosphere, like all rocks. A wide biodiversity was found in 21 chondrites and 8 martian stones, and was investigated with cell culture, microscopy techniques, PCR, and LAL photoluminetry. Some preliminary results are presented here. The sample suite included carbonaceous chondrites of types CR, CV, CK, CO, CI, and CM, from ANSMET and Falls. Past studies documented the alteration of meteorites by weathering and biological activity [1]-[4]. Unpublished observations during aqueous extraction for oxygen isotopic analysis [5], noted the formation of biofilms in water in a matter of days. In order to address the potential modification of meteoritic isotopic and chemical signatures, the culture of microbial contaminating species was initiated in 2005, and after a prolonged incubation, some of the species obtained from cell culture were analyzed in 2006. The results are preliminary, and a systematic catalog of microbial contaminants is developing very slowly due to lack of funding. Methods: The primary method was cell culture and PCR. Chondrites. Chondritic meteorite fragments were obtained by breaking stones of approximately one gram in sterile mortars. The core of the rocks, presumably less contaminated than the surface, was used for the present microbial study, and the

  10. Exploring the Potential Formation of Organic Solids in Chondrites and Comets through Polymerization of Interstellar Formaldehyde

    NASA Astrophysics Data System (ADS)

    Kebukawa, Yoko; Kilcoyne, A. L. David; Cody, George D.

    2013-07-01

    Polymerization of interstellar formaldehyde, first through the formose reaction and then through subsequent condensation reactions, provides a plausible explanation for how abundant and highly chemically complex organic solids may have come to exist in primitive solar system objects. In order to gain better insight on the reaction, a systematic study of the relationship of synthesis temperature with resultant molecular structure was performed. In addition, the effect of the presence of ammonia on the reaction rate and molecular structure of the product was studied. The synthesized formaldehyde polymer is directly compared to chondritic insoluble organic matter (IOM) isolated from primitive meteorites using solid-state 13C nuclear magnetic resonance, Fourier transform infrared, and X-ray absorption near edge structure spectroscopy. The molecular structure of the formaldehyde polymer is shown to exhibit considerable similarity at the functional group level with primitive chondritic IOM. The addition of ammonia to the solution enhances the rate of polymerization reaction at lower temperatures and results in substantial incorporation of nitrogen into the polymer. Morphologically, the formaldehyde polymer exists as submicron to micron-sized spheroidal particles and spheroidal particle aggregates that bare considerable similarity to the organic nanoglobules commonly observed in chondritic IOM. These spectroscopic and morphological data support the hypothesis that IOM in chondrites and refractory organic carbon in comets may have formed through the polymerization of interstellar formaldehyde after planetesimal accretion, in the presence of liquid water, early in the history of the solar system.

  11. EXPLORING THE POTENTIAL FORMATION OF ORGANIC SOLIDS IN CHONDRITES AND COMETS THROUGH POLYMERIZATION OF INTERSTELLAR FORMALDEHYDE

    SciTech Connect

    Kebukawa, Yoko; Cody, George D.; David Kilcoyne, A. L. E-mail: yoko@ep.sci.hokudai.ac.jp

    2013-07-01

    Polymerization of interstellar formaldehyde, first through the formose reaction and then through subsequent condensation reactions, provides a plausible explanation for how abundant and highly chemically complex organic solids may have come to exist in primitive solar system objects. In order to gain better insight on the reaction, a systematic study of the relationship of synthesis temperature with resultant molecular structure was performed. In addition, the effect of the presence of ammonia on the reaction rate and molecular structure of the product was studied. The synthesized formaldehyde polymer is directly compared to chondritic insoluble organic matter (IOM) isolated from primitive meteorites using solid-state {sup 13}C nuclear magnetic resonance, Fourier transform infrared, and X-ray absorption near edge structure spectroscopy. The molecular structure of the formaldehyde polymer is shown to exhibit considerable similarity at the functional group level with primitive chondritic IOM. The addition of ammonia to the solution enhances the rate of polymerization reaction at lower temperatures and results in substantial incorporation of nitrogen into the polymer. Morphologically, the formaldehyde polymer exists as submicron to micron-sized spheroidal particles and spheroidal particle aggregates that bare considerable similarity to the organic nanoglobules commonly observed in chondritic IOM. These spectroscopic and morphological data support the hypothesis that IOM in chondrites and refractory organic carbon in comets may have formed through the polymerization of interstellar formaldehyde after planetesimal accretion, in the presence of liquid water, early in the history of the solar system.

  12. Spatial Drivers in the Origin and Composition of Dissolved Organic Matter in Snow: Implications for Proglacial Stream Biogeochemistry

    NASA Astrophysics Data System (ADS)

    Fellman, J.; Hood, E. W.; Raymond, P. A.; Stubbins, A.; Spencer, R. G.

    2014-12-01

    The Coast Mountains of southeast Alaska are currently experiencing high rates of glacier volume loss. Continued glacier wastage therefore has the potential to decrease the proportion of streamflow derived from glacial runoff, which could alter the nature of dissolved organic matter (DOM) delivered to proglacial streams. We collected snow from ten locations along a transect that extended from the coast 47 km across the Juneau Icefield, southeast Alaska and analyzed the snow for δ18O and DOM for 13C, 14C and fluorescence characteristics. Our goal was to assess the origin and quality of DOM in snow to better understand how continued glacial recession in the region may influence the transfer of organic matter to proglacial aquatic ecosystems. The δ18O of snow decreased with distance from the coast (r2=84, p<0.01) indicative of the natural fractionation or fallout of heavy δ18O that occurs along elevation or spatial gradients. This depletion in the isotopic signature of snow across the Icefield transect was reflected in the origin and quality of DOM. Concentrations of dissolved organic carbon (DOC) varied from 0.13 to 0.29 mg C L-1 and progressively decreased (r2=43, p<0.05) as δ18O became more depleted. The Δ14C-DOC varied from -742 to -420‰ and showed progressive depletion with decreasing δ18O (r2=56, p<0.01). Older DOC corresponded to a decrease in the percent contribution of humic-like fluorescence (r2=74, p<0.01) suggesting an overall decrease in modern continental DOM across the transect. A three-source isotope mixing model showed that DOM in snow originates mainly from anthropogenic aerosols from fossil fuel combustion (45-74%) and marine sources (17-34%). These results suggest that anthropogenic aerosols are a quantitatively important source of relic DOM to the glacier ecosystem. Given relic DOM exported from glaciers is highly bioavailable, anthropogenic aerosols could profoundly influence the transfer of DOM from glaciers to proglacial aquatic

  13. Organic compounds in the Forest Vale, H4 ordinary chondrite

    NASA Astrophysics Data System (ADS)

    Zenobi, Renato; Philippoz, Jean-Michel; Zare, Richard N.; Wing, Michael R.; Bada, Jeffrey L.; Marti, Kurt

    1992-07-01

    We have analyzed the H4 ordinary chondrite Forest Vale for polycyclic aromatic hydrocarbons (PAHs) using two-step laser mass spectrometry (L 2MS) and for amino acids using a standard Chromatographic method. Indigenous PAHs were identified in the matrices of freshly cleaved interior faces but could not be detected in pulverized silicates and chondrules. No depth dependence of the PAHs was found in a chipped interior piece. Amino acids, taken from the entire sample, consisted of protein amino acids that were nonracemic, indicating that they are terrestrial contaminants. The presence of indigenous PAHs and absence of indigenous amino acids provides support for the contention that different processes and environments contributed to the synthesis of the organic matter in the solar system.

  14. Diverse origins and pre-depositional histories of organic matter in contemporary Chinese marginal sea sediments

    NASA Astrophysics Data System (ADS)

    Tao, Shuqin; Eglinton, Timothy I.; Montluçon, Daniel B.; McIntyre, Cameron; Zhao, Meixun

    2016-10-01

    Marginal seas are estimated to account for up to 90% of organic carbon (OC) burial in marine sediments, and thus play an important role in global carbon cycle. However, comprehensive assessments of carbon budgets for marginal sea systems are challenging due to their inherent complexity, with spatial and temporal variability in carbon inputs and dispersal processes. We examine the Bohai Sea and Yellow Sea (BS-YS) in order to further our understanding of sedimentary OC delivery, translocation and accumulation in a shallow marginal sea system. Bulk properties and the content and isotopic compositions (Δ14C, δ13C) of source-specific plant wax n-alkyl lipid biomarkers were determined for a suite of surficial sediment samples. Variable δ13C values (-25.1‰ to -28.5‰) and contemporary radiocarbon ages of short-chain n-fatty acids (FAs; C16, C18) reflect modern autochthonous marine and/or fresh terrestrial plant input. In contrast, extremely depleted Δ14C values (-932‰ to -979‰) of short-chain n-alkanes (C16, C18) suggest a predominant input from sedimentary rocks (petrogenic OC) or petroleum. Abundance-weighted average δ13C and Δ14C values of long-chain leaf wax lipids (C26+28+30n-FAs, C24+26+28n-alkanols, C27+29+31n-alkanes) are -29.1 ± 1.1‰ to -30.2 ± 0.3‰, and -286 ± 150‰ to -442 ± 119‰, respectively, illustrating that terrestrial OC delivery is dominated by pre-aged (∼3000-5000 14C yrs) C3 vegetation sources. A coupled carbon-isotopic mixing model, based on the bulk and compound-specific biomarker δ13C and Δ14C values, is used to partition the BS-YS sedimentary OC into three components that reflect both origins and transport processes. For all sampling sites, 31-64% is modern/contemporary OC, 24-49% is pre-aged terrestrial OC, and 7-26% is fossil OC, the latter likely derived from both physical erosion of ancient sedimentary rocks and fossil fuel sources. Pre-aged soil OC is most prominent in front of the modern and old Huanghe (Yellow

  15. Bulk and Grain Denstities of Allende and other Carbonaceous Chondrites

    NASA Astrophysics Data System (ADS)

    Macke, Robert

    2007-10-01

    Density and porosity are fundamental physical properties of meteorites. These data shed light on the origins, processes, and evolution of meteorite parent bodies and provide ground-truth data on asteroids. As part of an ongoing project to catalog densities and porosities of meteorites, we measured these properties on a number of samples in the collection at the American Museum of Natural History (AMNH) in New York. In addition, it is important to know the extent to which these properties may vary within one particular fall. AMNH holds a significant number of fragments of the CV chondrite Allende, yielding numerous individual pieces. By measuring density and porosity of as many of these pieces as possible, we get and indication of the degree of uniformity of the fall. Bulk densities were measured using the glass bead method [1,2]. Grain densities were measured using a Quantachrome Ultrapycnometer helium pycnometer, and porosities were calculated from the bulk and grain densities. We will report on density and porosity measurements of approximately 30 different chondrites of various classifications, many of which consisting of more than one piece. Bulk and grain densities were measured for at least 27 pieces of Allende, as well as 8 pieces of the CK meteorite Karoonda. References: [1] Consolmagno G.J. and Britt D.T. 1998. Meteoritics and Planetary Science 33:1231-1240. [2] Wilkison S.L. and Robinson M.S. 2000. Meteoritics and Planetary Science 35:1203-1213.

  16. Volatile elements in chondrites - Metamorphism or nebular fractionation

    NASA Technical Reports Server (NTRS)

    Takahashi, H.; Gros, J.; Higuchi, H.; Morgan, J. W.; Anders, E.

    1978-01-01

    Three of the most highly metamorphosed meteorites of their respective classes, Shaw (LL7), Karoonda (C5), and Coolidge (C4), were analyzed by radiochemical neutron activation analysis for Ag, Au, Bi, Br, Cd, Cs, Ge, In, Ir, Ni, Os, Pd, Rb, Re, Sb, Se, Te, Tl, U, and Zn. Comparison with data by Lipschutz and coworkers (1977) on artificially heated primitive meteorites shows that the natural metamorphism of meteorites cannot have taken place in a system open to volatiles. Shaw, metamorphosed at 1300 C for more than 1 million yr, is less depleted in In, Bi, Ag, Te, Zn, and Tl than Krymka heated at 1000 C for 1 week. Karoonda, metamorphosed at 600 C for many millennia, is less depleted in Bi and Tl than Allende heated at 600 C for 1 week. Data on primordial noble gases also show that the volatile-element patterns of ordinary and carbonaceous chondrites were established by nebular condensation and changed little, if at all, during metamorphism. For enstatite chondrites, the evidence is still incomplete but seems to favor a nebular origin of the volatile pattern.

  17. The Križevci H6 Chondrite and the Origin of H Chondrites

    NASA Astrophysics Data System (ADS)

    Lyon, I.; Andreic, Z.; Segon, D.; Korlevic, K.

    2014-09-01

    The Krizevci H6 meteorite was observed to fall in 2011 in Croatia. Photometry of the bolide by the Croatian meteor network determined an orbit and a 291g stone recovered. The distribution of metal grains infers the identity of the H6 parent body.

  18. Spectral reflectance properties of carbonaceous chondrites: 8. “Other” carbonaceous chondrites: CH, ungrouped, polymict, xenolithic inclusions, and R chondrites

    NASA Astrophysics Data System (ADS)

    Cloutis, E. A.; Hudon, P.; Hiroi, T.; Gaffey, M. J.; Mann, P.

    2012-11-01

    We have analyzed reflectance spectra (0.3-2.5 μm) of a number of ungrouped or tentatively grouped carbonaceous chondrites (CCs), possible CC-type xenoliths in an aubrite (Cumberland Falls) and a howardite (PRA 04401), a CH chondrite (PCA 91467), a CC polymict breccia (Kaidun), and some R chondrites. The best approach to analysis relies largely on characterizing spectrally active phases - i.e., those phases that contribute diagnostic absorption features, involving absorption band wavelength position, band depth, shape of absorption features, combined with albedo and spectral slope. Mafic silicate (hydrous and/or anhydrous) absorption features are ubiquitous in the CCs and R chondrites we have examined. Combining information on these features along with albedo and spectral slopes allows reasonable inferences to be made concerning their uniqueness. Reflectance spectra of Coolidge show contributions from both olivine and Fe oxyhydroxides (from terrestrial weathering), and its high reflectance and mafic silicate band depths are consistent with a petrologic grade >3 and inconsistent with CVs. The CC nature of the Cumberland Falls inclusions from spectral analysis is inconclusive, but they do exhibit spectral features consistent with their overall mineralogy. DaG 430, which has petrologic characteristics of both CV and CK chondrites, has a spectrum that is not fully consistent with either group. The spectrum of EET 96029 is consistent with some, but not all CM2 chondrites. GRO 95566, a meteorite with some affinities to CM2s, most resembles the Renazzo CR2 chondrite, consistent with their similar mineralogies, and its spectral properties can be related to its major mineralogic characteristics. Spectra of Kaidun are most consistent with CR chondrites, which form the bulk of this meteorite. The reflectance spectrum of MCY 92005 is consistent with its recent classification as a CM2 chondrite. The R3 chondrite MET 01149 shares many characteristics with CKs, but differs in

  19. Chemical and physical studies of type 3 chondrites. XI - Metamorphism, pairing, and brecciation of ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Sears, D. W. G.; Hasan, F. A.; Batchelor, J. D.; Lu, J.

    1991-01-01

    The present study reports recent measurements of the induced thermoluminescence (TL) properties of 69 type-3 ordinary chondrites, bringing to 125 the number of type-3 ordinary chondrites for which TL data are available. The samples include several of the particularly low petrographic type and many breccias, some of them gas-rich. The significance of the data with respect to the physical conditions affecting metamorphism is discussed. The TL data, olivine heterogeneity, carbon content, and inert-gas content were used to assign the samples to petrologic types. Twelve meteorites were identified as being type 3.0-3.2, and 10 of the breccias were found to contain material that may also be of this type. The temperature and width of the induced TL peak are also related to thermal history, with type 3.2-3.4 chondrites tending to have narrower peaks at lower glow curve temperatures than the type 3.6-3.9 chondrites. Type 3 H chondrites were found to be a higher petrographic type than the type 3 L and LL chondrites.

  20. Evidence of Microfossils in Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.; Rozanov, Alexei Y.; Zhmur, S. I.; Gorlenko, V. M.

    1998-01-01

    Investigations have been carried out on freshly broken, internal surfaces of the Murchison, Efremovka and Orgueil carbonaceous chondrites using Scanning Electron Microscopes (SEM) in Russia and the Environmental Scanning Electron Microscope (ESEM) in the United States. These independent studies on different samples of the meteorites have resulted in the detection of numerous spherical and ellipsoidal bodies (some with spikes) similar to the forms of uncertain biogenicity that were designated "organized elements" by prior researchers. We have also encountered numerous complex biomorphic microstructures in these carbonaceous chondrites. Many of these complex bodies exhibit diverse characteristics reminiscent of microfossils of cyanobacteria such as we have investigated in ancient phosphorites and high carbon rocks (e.g. oil shales). Energy Dispersive Spectroscopy (EDS) analysis and 2D elemental maps shows enhanced carbon content in the bodies superimposed upon the elemental distributions characteristic of the chondritic matrix. The size, distribution, composition, and indications of cell walls, reproductive and life cycle developmental stages of these bodies are strongly suggestive of biology' These bodies appear to be mineralized and embedded within the meteorite matrix, and can not be attributed to recent surface contamination effects. Consequently, we have interpreted these in-situ microstructures to represent the lithified remains of prokaryotes and filamentous cyanobacteria. We also detected in Orgueil microstructures morphologically similar to fibrous kerite crystals. We present images of many biomorphic microstructures and possible microfossils found in the Murchison, Efremovka, and Orgueil chondrites and compare these forms with known microfossils from the Cambrian phosphate-rich rocks (phosphorites) of Khubsugul, Northern Mongolia.

  1. Classification of six ordinary chondrites from Texas

    NASA Astrophysics Data System (ADS)

    Ehlmann, Arthur J.; Keil, Klaus

    1988-12-01

    Based on optical microscopy, modal and electron microprobe analyses, six ordinary chondrites from Texas were classified in compositional groups, petrologic types, and shock facies. These meteorites are Comanche (stone), L5c; Haskell, L5c; Deport (a), H4b; Naruna (a), H4b; Naruna (b), H4b; and Clarendon (b), H5d.

  2. Intensive parameters of enstatite chondrite metamorphism

    NASA Technical Reports Server (NTRS)

    Fogel, Robert A.; Hess, Paul C.; Rutherford, Malcolm J.

    1989-01-01

    A geothermometer based on the assemblage kamacite-quartz-enstatite-oldhamite-troilite found in enstatite chondrites is described. Data obtained with the geothermometer reveal that the EL6 meteorites experienced temperatures exceeding 1000 C. These temperatures imply a metal-sulfide melting event that may have fractionated the melt from the source region.

  3. Classification of four ordinary chondrites from Spain

    NASA Technical Reports Server (NTRS)

    Mccoy, T. J.; Keil, Klaus; Casanova, I.; Wieler, R.

    1990-01-01

    Based on optical microsocpy and electron microprobe analysis of mafic minerals, four previously poorly described ordinary chondrites from Spain are classified. The classifications of Guarena (H6), Olmedilla de Alarcon (H5) and Reliegos (L5) are confirmed. Molina is reclassified as H5, based on new data.

  4. Hf-W Chronology of CR Chondrites

    NASA Astrophysics Data System (ADS)

    Budde, G.; Kruijer, T. S.; Kleine, T.

    2017-02-01

    Hf-W systematics of CR chondrites define an age of 3.7 Ma after CAIs for CR chondrule formation. CR metal and silicates have complementary nucleosynthetic W and Mo isotope anomalies due to the uneven distribution of a presolar s-process carrier.

  5. Intensive parameters of enstatite chondrite metamorphism

    NASA Technical Reports Server (NTRS)

    Fogel, Robert A.; Hess, Paul C.; Rutherford, Malcolm J.

    1989-01-01

    A geothermometer based on the assemblage kamacite-quartz-enstatite-oldhamite-troilite found in enstatite chondrites is described. Data obtained with the geothermometer reveal that the EL6 meteorites experienced temperatures exceeding 1000 C. These temperatures imply a metal-sulfide melting event that may have fractionated the melt from the source region.

  6. Sm-Nd Systematics of Chondrites

    NASA Astrophysics Data System (ADS)

    Amelin, Y.; Rotenberg, E.

    2004-03-01

    ^147Sm-^143Nd and ^146Sm-^142Nd systems are studied in phosphates and chondrules from nine chondrites. The ^147Sm-^143Nd isochron age is 4588±100 Ma. Initial ^146Sm/^144Sm is 0.0075±0.0027. The validity of currently used CHUR parameters is confirmed.

  7. Carbonaceous structures in the Tissint Martian Meteorite: evidence of a biogenetic origin

    NASA Astrophysics Data System (ADS)

    Wallis, Jamie; Wickramasinghe, N. C.; Wallis, Daryl H.; Miyake, Nori; Wallis, M. K.; Hoover, Richard B.

    2015-09-01

    We report for the first time