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Sample records for chondrite matter originally

  1. 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.

  2. 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.

  3. Isotopic composition of carbonaceous-chondrite kerogen Evidence for an interstellar origin of organic matter in meteorites

    NASA Technical Reports Server (NTRS)

    Kerridge, J. F.

    1983-01-01

    Stepwise combustion has revealed systematic patterns of isotopic heterogeneity for C, H and N in the insoluble organic fraction (m-kerogen) from the Orgueil and Murray carbonaceous chondrites. Those patterns are essentially identical for both meteorites, indicating a common source of m-kerogen. The data cannot be reconciled with a single mass-fractionation process acting upon a single precursor composition. This indicates either a multi-path history of mass-dependent processing or a significant nucleogenetic contribution, or both. If mass-fractionation were the dominant process, the magnitude of the observed isotopic variability strongly suggests that ion-molecule reactions at very low temperatures, probably in interstellar clouds, were responsible. In any case, an interstellar, rather than solar nebular, origin for at least some of the meteoritic organic matter is indicated. This has interesting implications for the origin of prebiotic molecules, temperatures in the early solar system, and the isotopic compositions of volatiles accreted by the terrestrial planets.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. Nature and origin of C-rich ordinary chondrites and chondritic clasts

    NASA Technical Reports Server (NTRS)

    Scott, E. R. D.; Brearley, A. J.; Keil, K.; Grady, M. M.; Pillinger, C. T.

    1988-01-01

    The abundance and the isotopic compositions of C, O, and noble gases were investigated together with the petrologic characteristics of four carbon-rich ordinary chondrites (Sharps and Allan Hills A77011, A78119, and A81024) and three C-rich chondritic clasts. The results of the analyses suggest that all of the chondrites and clasts analyzed belong to petrologic type 3 and contain abundant carbon-rich aggregates, which, in at least two of these samples, consist of poorly graphitized carbon commonly associated with metallic Fe,Ni. The data also suggest that the four C-rich chondrites originated on the H, L, and LL parental bodies, but that clasts in Dimmitt and Plainview and other regolith breccias may come from different bodies. The results obtained are consistent with the view that graphite is not a common nebular phase.

  9. Origin of plagioclase-olivine inclusions in carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

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

    1991-02-01

    The origin of plagioclase-olivine inclusions (POIs) from three CV chondrites and one ungrouped chondrite was investigated by examining the chemical, mineralogical, and isotopic characteristics of a group of POIs from these chondrites. Results of these analyses demonstrate that the mixing and the partial melting processes in these inclusions were superimposed on more ancient isotopically heterogeneous material. A comparison of the essential characteristics of POIs and CAIs suggests that the major processes leading to the formation of POIs (such as condensation, dust/gas fractionation, aggregation of chemically and isotopically disparate materials, and partial melting) are common to most CAIs and chondrules. A scenario for the origin of POIs is proposed, showing that the homogeneity of the final assemblage (whether a POI, a CAI, or a chondrite) is primarily a reflection of the thermal history rather than the nature of precursor materials.

  10. 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.

  11. Establishment of redox conditions during planetary collisions as an origin of chondrites

    NASA Technical Reports Server (NTRS)

    Tsuchiyama, A.; Kitamura, M.

    1994-01-01

    Collisions between a 'cometlike' body (mixtures of chondritic materials and ice) and a slightly differentiated body were proposed for shock origin of ordinary chondrites. In this model, chondrules were formed with shock melting, and matrices were formed both by fracturing of materials and by recondensation of evaporated materials. This model can explain different redox conditions of chondrite formations by ice evaporation. Although this model was originally proposed for ordinary chondrites, we assume here that the model can be extended to chondrite formation in general. In this paper, redox conditions during chondrite formation by collisions will be discussed in the light of phase diagrams for solid-vapor equilibria.

  12. Zn Isotopes in Chondrites, Chondrules, and Matrix: Origin of the Volatile Element Depletion in Chondrites

    NASA Astrophysics Data System (ADS)

    Moynier, F.; Pringle, E.; Hezel, D.

    2015-07-01

    The variations of Zn isotope ratios among carbonaceous chondrites show that the volatile element depletion in solar system material occurred in the solar nebula. We will also present the Zn isotopic composition of chondrules and matrix from carbonaceous chondrites.

  13. 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.

  14. Organic matter in carbonaceous chondrites, planetary satellites, asteroids and comets

    NASA Technical Reports Server (NTRS)

    Cronin, John R.; Pizzarello, Sandra; Cruikshank, Dale P.

    1988-01-01

    A detailed review is given of the organic compounds found in carbonaceous chondrite meteorites, especially the Murchison meteorite, and detected spectroscopically in other solar-system objects. The chemical processes by which the organic compounds could have formed in the early solar system and the conditions required for these processes are discussed, taking into account the possible alteration of the compounds during the lifetime of the meteoroid. Also considered are the implications for prebiotic evolution and the origin of life. Diagrams, graphs, and tables of numerical data are provided.

  15. 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.

  16. The matrices of unequilibrated ordinary chondrites - Implications for the origin and history of chondrites

    NASA Technical Reports Server (NTRS)

    Huss, G. R.; Keil, K.; Taylor, G. J.

    1981-01-01

    The matrices of 16 unequilibrated chondrites were examined by optical microscopy, an electron microprobe, and a scanning electron microscope. The fine-grained, opaque, silicate matrix of type 3 unequilibrated chondrites was compositionally, mineralogically, and texturally different from the chondrules and their fragments; it may be the low temperature condensate proposed by Larimer and Anders (1967, 1970). Each meteorite has been metamorphosed by a combination of processes including thermal metamorphism and the passage of shock waves; the appearance of each chondrite results from the temperature and pressure conditions which formed it, and subsequent metamorphic alterations.

  17. 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.

  18. 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

  19. Origin of zoned metal grains in the QUE94411 chondrite

    NASA Astrophysics Data System (ADS)

    Campbell, Andrew J.; Humayun, Munir; Meibom, Anders; Krot, Alexander N.; Keil, Klaus

    2001-01-01

    Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used to measure distributions of the siderophile elements P, V, Cr, Fe, Co, Ni, Mo, Ru, Rh, Pd, W, Re, Os, Ir, and Pt in metal grains in the metal-rich chondrite QUE94411 with a spatial resolution of ˜30 μm. The platinum group elements (PGEs), except Pd, exhibit radial zoning in these grains that mimics that previously observed in Ni and Co; the concentrations of these elements decreases from the cores to the rims of the grains. The PGE distributions support a condensation origin for the enhanced refractory element abundances in the zoned grains; the lack of zoning in Pd refutes an origin by a redox-controlled process, and none of the PGE-Ni relationships support an origin by fractional crystallization from a metallic melt. Several models of grain formation were explored, including equilibrium fractional condensation, which failed to yield the correct radial zoning. The zoning may be the product of a nonequilibrium fractional condensation process, in which the refractory siderophiles remained supersaturated in the cooling solar nebula, or of diffusion between refractory-enhanced Fe-Ni cores and other Fe-Ni metal that may have been deposited later from the solar nebula.

  20. 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

  1. 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.

  2. 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.

  3. A collisional origin to Earth's non-chondritic composition?

    NASA Astrophysics Data System (ADS)

    Bonsor, Amy; Leinhardt, Zoë M.; Carter, Philip J.; Elliott, Tim; Walter, Michael J.; Stewart, Sarah T.

    2015-02-01

    Several lines of evidence indicate a non-chondritic composition for bulk Earth. If Earth formed from the accretion of chondritic material, its non-chondritic composition, in particular the super-chondritic 142Nd /144Nd and low Mg/Fe ratios, might be explained by the collisional erosion of differentiated planetesimals during its formation. In this work we use an N-body code, that includes a state-of-the-art collision model, to follow the formation of protoplanets, similar to proto-Earth, from differentiated planetesimals (>100 km) up to isolation mass (>0.16 M⊕). Collisions between differentiated bodies have the potential to change the core-mantle ratio of the accreted protoplanets. We show that sufficient mantle material can be stripped from the colliding bodies during runaway and oligarchic growth, such that the final protoplanets could have Mg/Fe and Si/Fe ratios similar to that of bulk Earth, but only if Earth is an extreme case and the core is assumed to contain 10% silicon by mass. This may indicate an important role for collisional differentiation during the giant impact phase if Earth formed from chondritic material.

  4. 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

  5. Testing the origin of the magnetic record of chondrites

    NASA Astrophysics Data System (ADS)

    Kohout, T.; Kletetschka, G.; Pesonen, L. J.; Wasilewski, P. J.

    2006-05-01

    The method for determination of the meteorite magnetic record origin has been developed by Kletetschka et al, 2005. The technique utilizes a detailed AF (Alternating Field) demagnetization of NRM (Natural Remanent Magnetization), followed by AF demagnetization of the SIRM (Saturation Isothermal Remanent Magnetization) in the very same AF steps. The ratio of NRM(AF)/SIRM(AF) is plotted against AF demagnetization field. The slope of the NRM(AF)/SIRM(AF) curve contains information about the nature of NRM acquisition process. In the case of the TRM (ThermoRemanent Magnetization) or CRM (ChemoRemanent Magnetization) the coercivity spectrum of NRM should cover equally both the SD and MD particles resulting in the constant NRM(AF)/SIRM(AF) ratio. In the case of the IRM (Isothermal Remanent Magnetization) the low coercivity grains are much more susceptible to the magnetizing field that the high coercivity grains resulting in the increase of the NRM(AF)/SIRM(AF) ratio in the low coercivity (low AF field) region. We applied this method on three chondritic meteorites. The Neuschwanstein (EL6) reveals significant IRM component due to negative NRM(AF)/SIRM(AF) slope in the low AF fields. The chondrules of Bjurbole (L4) reveals constant NRM(AF)/SIRM(AF) ratio pointing on TRM (or CRM) origin of the NRM. The interesting feature was observed on chondrules from the Avanhandava (H4) meteorite. Systematically lower values of the NRM(AF)/SIRM(AF) ratio in the low AF range points to partial demagnetization of MD grains what can be explained as an effect of the impact demagnetization of the parent body or as an effect of the time-decay of the magnetization. The method can serve as fast tool to determine the nature and origin of the magnetic record of the extraterrestrial and terrestrial materials and has potential application in the paleointensity studies. Kletetschka G., Kohout T., Wasilewski P. J., Fuller M. (2005): Recognition of thermal remanent magnetization in rocks and meteorites

  6. 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.

  7. Petrography, mineral chemistry and origin of Type I enstatite chondrites

    NASA Technical Reports Server (NTRS)

    Leitch, C. A.; Smith, J. V.

    1982-01-01

    The petrography and mineralogy of four Type I enstatite chondrites were examined by optical and cathololuminescent and electron microprobe means to discern particular chemical and mechanical processes present during solar system condensation. The specimens examined included sections of the Indarch, Abee, Kota-Kota, and Adhi-Kot chondrites. Textural interpretations were performed, as well as chemical analyses of the degree of similarity of the clinoenstatite, olivine, accessory silicates, metal, schreibersite, troilite, oldhamite, and niningerite grains in each sample. Simple models of progressive condensation either at equilibrium or with mechanical removal of early condensates were ruled out due to the occurrence of both blue and red enstatite crystals in metal clasts. A need for sequential processes of mixing, melting, crystallization, condensation, fracturing, and mechanical aggregation are suggested as necessary to model the formation mechanisms of the mineral aggregates.

  8. Enstatite Chondrites, their Origin and the Composition of the Earth

    NASA Astrophysics Data System (ADS)

    Jacobsen, S. B.; Petaev, M. I.; Huang, S.

    2012-12-01

    The nearly identical O isotopic compositions of the enstatite chondrites (EC), Earth's mantle, and Moon have been used to argue that the EC provide the best Solar System material for estimating the chemical composition of the Earth. A possible link between the EC and Earth is further supported by recent observations that EC and Earth have the same isotopic compositions for both major and minor elements (O, Ca, Ti, Cr) which exhibit substantial variations among different chondrite groups, with Si being the only exception. However, there is a huge mismatch in chemical compositions between the EC and Earth. For example, the EC have much too high Rb/Sr and K/U ratios and are depleted in FeO and refractory lithophile elements compared to the composition of Earth's mantle deduced from terrestrial rocks. This discrepancy could be resolved by assuming that the Earth and EC had a common nebular precursor but they have experienced different chemical evolution. Such an assumption is supported by the mineralogy and O isotopic data for the most primitive EH3 chondrites. The abundant FeO-bearing silicates, compositionally similar to those in other classes of chondrites, are well documented in ECs, with most silicates having O isotopic compositions of the bulk EC values. Recent studies showed that the chalcophile behaviour of Ca, Mg, Na, and other elements in EC is due to secondary processing of FeO-bearing silicates in an H-poor environment with high fS2 (Fe-FeS buffer) and fO2 close to the CO-CO2 buffer. We suggest that a nebular reservoir that produced the precursor material for EC has also produced the building blocks for the Earth, chemically similar to the widely accepted Earth's composition derived from mantle peridotites. It is possible that the EC precursors initially formed in an isotopically homogeneous inner terrestrial planet region (Mercury, Venus, Earth) by the disruption of a planetesimal and then were scattered to an isotopically heterogeneous outer terrestrial

  9. Clues to the origin of sulfide minerals in CI chondrites

    NASA Technical Reports Server (NTRS)

    Kerridge, J. F.; Macdougall, J. D.; Marti, K.

    1979-01-01

    The dominant sulfide in CI carbonaceous chondrites is an Fe-deficient pyrrhotite containing about 1% Ni, Alais, Ivuna, and Orgueil also contain minor cubanite, CuFe2S3, and Alais minor pentlandite, (Fe,Ni)9S8. All pyrrhotites contain 39.4 + or - 0.1% S; Ni contents range from 0.7 to 1.3%. The phase diagrams reveal no temperature at which the observed pentlandite-pyrrhotite assemblage is at equilibrium. Similarly, the pyrrhotite composition alone are inconsistent with equilibrium formation from a gas of solar composition. In Xe from high-purity submilligram Orgueil pyrrhotite separates, the ratios Xe-129/Xe-132 are not significantly larger than those in trapped meteoritic Xe. The lack of positive evidence for extinct I-129 in pyrrhotite does not permit any inferences regarding cooling rates in the early solar nebula. It is concluded that sulfides in CI chondrites cannot be nebular condensates formed under equilibrium conditions. Argon isotopic abundances reveal the presence of significant spallation and trapped gas components in Orgueil pyrrhotite. The Orgueil exposure age is calculated to be at least about 10 m.y.

  10. 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.

  11. 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.

  12. Origin of fragmental and regolith meteorite breccias - Evidence from the Kendleton L chondrite breccia

    NASA Technical Reports Server (NTRS)

    Ehlmann, A. J.; Scott, E. R. D.; Keil, K.; Mayeda, T. K.; Clayton, R. N.

    1988-01-01

    Nine specimens of the Kendleton L chondrite, chosen (from the total of 52 that were inspected) for the presence of a wide variety of clasts, were studied microscopically as well as by EMPA with the purpose of investigating the origin of regolith and fragmental meteorite breccias. The results indicate that Kendleton does not contain detectable amounts of solar-wind gases. The Kendleton clasts were found to include a wide variety of L3, L5, shock-blackened, and melt rock clasts, which are considered to have originated from normal L chondrite material, and a unique tridymite-rich inclusion. The results suggest that meteoritic regolith breccias may have different origin from that of lunar breccias.

  13. Toward an experimental synthesis of the chondritic insoluble organic matter

    NASA Astrophysics Data System (ADS)

    Biron, Kasia; Derenne, Sylvie; Robert, FrançOis; Rouzaud, Jean-NoëL.

    2015-08-01

    Based on the statistical model proposed for the molecular structure of the insoluble organic matter (IOM) isolated from the Murchison meteorite, it was recently proposed that, in the solar T-Tauri disk regions where (photo)dissociation of gaseous molecules takes place, aromatics result from the cyclization/aromatization of short aliphatics. This hypothesis is tested in this study, with n-alkanes being submitted to high-frequency discharge at low pressure. The contamination issue was eliminated using deuterated precursor. IOM was formed and studied using solid-state nuclear magnetic resonance, pyrolysis coupled to gas chromatography and mass spectrometry, RuO4 oxidation, and high-resolution transmission electron microscopy. It exhibits numerous similarities at the molecular level with the hydrocarbon backbone of the natural IOM, reinforcing the idea that the initial precursors of the IOM were originally chains in the gas. Moreover, a fine comparison between the chemical structure of several meteorite IOM suggests either that (i) the meteorite IOMs share a common precursor standing for the synthetic IOM or that (ii) the slight differences between the meteorite IOMs reflect differences in their environment at the time of their formation i.e., related to plasma temperature that, in turn, dictates the dissociation-recombination rates of organic fragments.

  14. 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

  15. Experimental simulation of organic matter alteration in carbonaceous chondrites under an in situ micro FTIR spectroscopy

    NASA Astrophysics Data System (ADS)

    Kebukawa, Y.; Nakashima, S.; Saiki, K.; Zolensky, M. E.

    2007-12-01

    Carbonaceous chondrites contain organic matter up to a few weight percents, most of which consists of kerogen- like macromolecular material. Chondritic organic matter preserves signatures of various evolutional steps from presolar materials, through aqueous alteration and thermal metamorphism in the parent asteroid up to delivery to the Earth. The organic-mineral interactions during these processes are little known. We report here on the experimental simulation of organic matter alteration on carbonaceous chondrite parent body under micro FTIR spectroscopy with a heating stage. Leonardite humic acid (IHSS standard humic acid) and synthetic saponite or natural antigorite were used as the macromolecular organic matter and the matrix mineral. These powdered samples were dispersed by MilliQ water then dropped on a CaF2 plate and dried. They were heated in the heating stage from room temperature to 600 °C with a heating rate of 10 °C/min in air, Ar gas, and H2+CO2 gas mixture (mixing ratio 1:1). H2+CO2 gas mixture enables controls of not only oxygen fugacity but also water vapor fugacity, and aqueous processing on chondrite parent bodies can be partly simulated. IR spectra were collected at every 20 °C under the micro FTIR spectroscopy. Aliphatic C-H increased from room temperature to approximately 250 °C then decreased. Aromatic C-H increased from room temperature to around 400-450 °C then decreased. These aliphatic C-H decrease and aromatic C-H increase are faster in air than in Ar or H2+CO2. These CH changes of leonardite humic acid are slower with the presence of saponite. These results indicate that organic matter transformation might be prevented by the clay mineral (saponite). Some carbonaceous chondrite samples mixed with the organic material (leonardite humic acid) will also be investigated by the same way. These results will elucidate interactions of chondritic macromolecular organic matter with matrix minerals during parent body processes.

  16. 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).

  17. Determination of the petrologic type of CV3 chondrites by Raman spectroscopy of included organic matter

    NASA Astrophysics Data System (ADS)

    Bonal, Lydie; Quirico, Eric; Bourot-Denise, Michèle; Montagnac, Gilles

    2006-04-01

    This paper reports the first reliable quantitative determination of the thermal metamorphism grade of a series of nine CV3 chondrites: Allende, Axtell, Bali, Mokoia, Grosnaja, Efremovka, Vigarano, Leoville, and Kaba. The maturity of the organic matter in matrix, determined by Raman spectroscopy, has been used as a powerful metamorphic tracer, independent of the mineralogical context and extent of aqueous alteration. This tracer has been used along with other metamorphic tracers such as Fe zoning in type-I chondrules of olivine phenocrysts, presolar grain abundance and noble gas abundance (bulk and P3 component). The study shows that the petrologic types determined earlier by Induced ThermoLuminescence were underestimated and suggests the following values: PT (Allende-Axtell) >3.6; PT (Bali-Mokoia-Grosnaja) ˜3.6; PT (Efremovka-Leoville-Vigarano) = 3.1-3.4; PT (Kaba) ˜3.1. The most commonly studied CV3, Allende, is also the most metamorphosed. Bali is a breccia containing clasts of different petrologic types. The attribution suggested by this study is that of clasts of the highest petrologic types, as pointed out by IOM maturity and noble gas bulk abundance. CV3 chondrites have complex asteroidal backgrounds, with various degrees of aqueous alteration and/or thermal metamorphism leading to complex mineralogical and petrologic patterns. (Fe,Mg) chemical zoning in olivine phenocrysts, on the borders of type I chondrules of porphyritic olivine- and pyroxene-rich textural types, has been found to correlate with the metamorphism grade. This suggests that chemical zoning in some chondrules, often interpreted as exchanges between chondrules and nebular gas, may well have an asteroidal origin. Furthermore, the compositional range of olivine matrix is controlled both by thermal metamorphism and aqueous alteration. This does not support evidence of a nebular origin and does not necessarily mirror the metamorphism grade through (Fe,Mg) equilibration. On the other hand, it may

  18. Alternative hypothesis for the origin of CCF xenon. [Carbonaceous-Chondrite-Fission xenon

    NASA Technical Reports Server (NTRS)

    Black, D. C.

    1975-01-01

    The relative abundances and origins of the xenon isotopes found in carbonaceous meteorites are discussed. It is proposed that carbonaceous-chondrite-fission (CCF) xenon is not caused by fission, but is the direct result of a modified r-process nucleosynthesis which produces a peak at Z = 54 and N = 82. The xenon produced in this way would have been trapped in dust grains which were subsequently incorporated in the solar system with minimal degassing.

  19. Oxygen Isotopic and Petrological Constraints on the Origin and Relationship of IIE Iron Meteorites and H Chondrites

    NASA Astrophysics Data System (ADS)

    McDermott, K. H.; Greenwood, R. C.; Franchi, I. A.; Anand, M.; Scott, E. R. D.

    2011-03-01

    New oxygen isotopic measurements of IIEs and H chondrites are indistinguishable — strengthening a possible common origin for these groups. Combining oxygen results with mineralogy, the nature of their parent body or bodies can be explored.

  20. 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.

  1. Nonporphyritic chondrules and chondrule fragments in enstatite chondrites: Insights into their origin and secondary processing

    NASA Astrophysics Data System (ADS)

    Varela, M. E.; Sylvester, P.; BrandstäTter, F.; Engler, A.

    2015-08-01

    Sixteen nonporphyritic chondrules and chondrule fragments were studied in polished thin and thick sections in two enstatite chondrites (ECs): twelve objects from unequilibrated EH3 Sahara 97158 and four objects from equilibrated EH4 Indarch. Bulk major element analyses, obtained with electron microprobe analysis (EMPA) and analytical scanning electron microscopy (ASEM), as well as bulk lithophile trace element analyses, determined by laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS), show that volatile components (K2O + Na2O versus Al2O3) scatter roughly around the CI line, indicating equilibration with the chondritic reservoir. All lithophile trace element abundances in the chondrules from Sahara 97158 and Indarch are within the range of previous analyses of nonporphyritic chondrules in unequilibrated ordinary chondrites (UOCs). The unfractionated (solar-like) Yb/Ce ratio of the studied objects and the mostly unfractionated refractory lithophile trace element (RLTE) abundance patterns indicate an origin by direct condensation. However, the objects possess subchondritic CaO/Al2O3 ratios; superchondritic (Sahara 97158) and subchondritic (Indarch) Yb/Sc ratios; and chondritic-normalized deficits in Nb, Ti, V, and Mn relative to RLTEs. This suggests a unique nebular process for the origin of these ECs, involving elemental fractionation of the solar gas by the removal of oldhamite, niningerite, and/or another phase prior to chondrule condensation. A layered chondrule in Sahara 97158 is strongly depleted in Nb in the core compared to the rim, suggesting that the solar gas was heterogeneous on the time scales of chondrule formation. Late stage metasomatic events produced the compositional diversity of the studied objects by addition of moderately volatile and volatile elements. In the equilibrated Indarch chondrules, this late process has been further disturbed, possibly by a postaccretional process (diffusion?) that preferentially mobilized Rb with

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

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

    PubMed

    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

  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. 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.

  6. Origin of SiO 2-rich components in ordinary chondrites

    NASA Astrophysics Data System (ADS)

    Hezel, Dominik C.; Palme, Herbert; Nasdala, Lutz; Brenker, Frank E.

    2006-03-01

    Silica-rich objects are common minor components in ordinary chondrites (OC), occurring as fragments and as chondrules. Their typical paragenesis is orthopyroxene + SiO 2 (with bulk SiO 2 >65 wt%) and occasionally with additional olivine and/or spinel. Individual silica-rich components (SRC) have previously been studied in various types of OCs, although there is only one comprehensive study of these objects by Brigham et al. [Brigham, C.A., Murrell, M.T., Yabuki, H., Ouyang, Z., El Goresy, A., 1986. Silica-bearing chondrules and clasts in ordinary chondrites. Geochim. Cosmochim. Acta 50, 1655-1666]. Several different explanations of how SRCs formed have been published. The main question is how silica-enrichment was achieved, because CI-chondritic atomic Mg/Si-ratio is 1.07 and as a consequence only olivine and pyroxene, but no free silica should be stable. There are two basic possibilities for the SiO 2-enrichment: (1) a RedOx-mechanism or magmatic fractionation on the parent body and (2) fractional condensation or recycling of chondrule mesostasis in the solar nebula. To better constrain the origin of these objects, we measured major and rare earth elements in SRCs of various types of ordinary chondrites, and in addition, we studied silica polymorphism in these objects using an in situ micro-Raman technique. Bulk chondrule compositions define mixing lines between the compositions of olivine and pyroxene. The SRCs extend these lines to an SiO 2 end member. In contrast, magmatic trends grossly deviate from these mixing lines. Concentrations of CaO, Al 2O 3, and REE in the pyroxenes of the SRCs are low (0.01 to 1× CI) and the CI-normalized REE-patterns are virtually flat, typical of bulk chondrules, but untypical of magmatic trends. We therefore conclude that SiO 2-rich objects are not of magmatic origin. They are the result of fractional condensation in the solar nebula. The silica in SRCs occurs mainly as tridymite and sometimes as cristobalite or—in very rare

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

    NASA Astrophysics Data System (ADS)

    Fegley, B.; Post, J. E.

    1985-11-01

    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.

  8. 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.

  9. In situ characterization of organic matter in two primitive chondrites through correlated microanalytical techniques

    NASA Astrophysics Data System (ADS)

    Wende, A. M.; Nittler, L.; Steele, A.; Herd, C. D.

    2009-12-01

    Primitive meteorites contain up to 2 wt % C, much of it in the form of insoluble organic matter (IOM). Bulk analyses have revealed the IOM to be marked by large D and 15N enrichments relative to terrestrial values. Isotopic imaging studies have revealed the presence of `hotspots’, sub-μm to μm-sized regions of IOM exhibiting extreme isotope enrichments. An interesting subpopulation of organic grains, ’nanoglobules’, which have hollow, spherical morphologies, is known to account for a portion of these hot spots. Previous work has suggested that nanoglobules can be identified in situ by native UV fluorescence. The isotopic enrichments are believed to point to low-T chemical fractionations either in the interstellar medium (ISM) or the outer regions of the early Solar System. As part of a larger study investigating the origin and evolution of IOM in the Solar System, a correlated, in situ, microanalytical approach was employed to characterize local isotopic and morphological heterogeneities in IOM in the highly primitive chondrites QUE 99177 (CR3) and Tagish Lake (C-ung). Previous NanoSIMS ion imaging of a QUE 99177 section revealed the spatial and isotopic distribution of C in the matrix with a spatial resolution of 200 nm. Manual definition of >3300 C-rich regions in the NanoSIMS images indicates that grains smaller than 1 μm across, which account for 80% of the IOM area, have a size distribution that is similar to estimates of the size distribution of carbonaceous dust in the diffuse ISM, supporting an interstellar origin for the IOM. Micro-Raman spectroscopy, which is highly sensitive to the degree of disorder in carbonaceous materials, was attempted on the same regions analyzed by NanoSIMS in QUE 99177. Unfortunately, surface damage due to both the prior SIMS analyses and removal of a prior C coat precluded acquisition of useful Raman spectra. Consequently, future correlated work will entail performing Raman analyses on uncoated samples prior to SIMS

  10. The origin of the neon isotopes in chondrites and on Earth

    NASA Astrophysics Data System (ADS)

    Moreira, Manuel; Charnoz, Sébastien

    2016-01-01

    We discuss the origin of the neon isotopic signatures in chondrites and in the terrestrial mantle. There are two primary possible origins for neon in the Earth's mantle. One origin is the dissolution of a dense primordial atmosphere with a solar composition of 20Ne/22Ne >13.4 into the mantle in a possible magma ocean stage during Earth's accretion. The second origin, developed in this study, is that mantle neon was already in Earth's parent bodies because of refractory grain irradiation by solar wind. We propose that solar wind implantation occurred early on dust within the accretion disk to allow such irradiation. Because solar wind implantation fractionates neon isotopes, the heavier isotopes are implanted deeper than the lighter ones because of different kinetic energies, and the process of implantation, if coupled with sputtering, leads to a steady state neon isotopic ratio (20Ne/22Ne ∼12.7) that is similar to what is observed in mantle-derived rocks (12.5-12.9), lunar soil grains (∼12.9) and certain gas-rich chondrites from all classes (enstatite, ordinary, rumuruti). Using a dust transport model in a turbulent and irradiated solar nebula, we estimated the equivalent irradiation age of a population of dust particles at three different distances from the sun (0.8, 1, 1.2 AU) and converted these ages into neon concentrations and isotopic ratios. The dust subsequently coagulated to form Earth's parent bodies, which have the mean neon isotopic composition of the irradiated dust (non-irradiated dust is assumed to be free of neon). If this scenario of solar wind implantation coupled with sputtering in the precursors of Earth's parent bodies is correct, it offers a simple alternative to the model of solar nebula gas incorporation by dissolution in a magma ocean.

  11. Hydrogen isotope evidence for the origin and evolution of the carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Eiler, John M.; Kitchen, Nami

    2004-03-01

    We present new hydrogen isotope data for separated matrix, hydrated chondrules, and other hydrated coarse silicate fragments from nine carbonaceous chondrites. These data were generated using a micro-analytical method involving stepped combustion of tens to hundreds of micrograms of hydrous solids. We also re-evaluate hydrogen isotope data from previous conventional stepped combustion experiments on these and other carbonaceous chondrites. Hydrogen isotope compositions of matrix and whole-rock samples of CM chondrites are correlated with oxygen isotope indices, major and minor-element abundances, and abundance and isotope ratios of other highly volatile elements. These correlations include a monotonic decrease in δD with increasing extent of aqueous alteration and decreasing abundances of highly volatile elements (including C, N and Ar), between extremes of ˜0‰ (least altered, most volatile rich) and -200‰ (most altered, least volatile rich). In plots involving only abundances and/or isotope ratios of highly volatile elements, CI chondrites fall on the high-δD, volatile rich end of the trends defined by CM chondrites; i.e., CI chondrites resemble the least altered CM chondrites in these respects. These trends suggest the protoliths of the CM chondrites (i.e., before aqueous alteration) contained an assemblage of volatiles having many things in common with those in the CI chondrites. If so, then the volatile-element inventory of the CI chondrites was a more widespread component of early solar system objects than suggested by the scarcity of recognized CI meteorites. Differences in volatile-element chemistry between the CI and average CM chondrites can be attributed to aqueous alteration of the latter. Previous models of carbonaceous chondrite aqueous alteration have suggested: (1) the protoliths of the CM chondrites are volatile poor objects like the CO or CV chondrites; and (2) the CI chondrites are more altered products of the same process producing the CM

  12. 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.

  13. Searching for the Origins of Extraterrestrial Matter

    NASA Astrophysics Data System (ADS)

    Heying, E. K.; Cody, G. D.

    2008-12-01

    A relatively significant amount of Insoluble Organic Matter (IOM) is contained within chondritic meteorites. Although the chemical structure of this IOM has been analyzed, questions still speculate as to what molecule(s) and chemical reactions it has resulted from. The carbonaceous chondrite, Murchison, was analyzed with NMR spectroscopy revealing the abundance of furan and aromatic carbons in its chemical structure. With the formose reaction as a guideline, formose products were created using formaldehyde and glycolaldehyde in order to create products that could potentially be structurally similar to the IOM found in carbonaceous chondrites. Using NMR spectroscopy to analyze the chemical structure of these products, they were found to contain many of the same functional groups as the IOM from Murchison. The main difference was the increased amount of methine carbon present in the formose products, which also led to a lower amount of aromatic carbon than the Murchison. A possible solution to decrease the amount of methine is to find a way to dehydrogenate the formose products; therefore, increasing the amount of aromatic carbons due to creation of double bonds from the dehydrogenation mechanism. Overall, the formose reaction can still be considered to be a possible reaction pathway for the synthesis of primitive IOM. Further studies into how these organics evolved through chemical reactions will be able to yield more insight into some of the most primitive chemistry taking place in our galaxy.

  14. On origin of the olivine inclusions from the Kainsaz CO carbonaceous chondrite

    NASA Technical Reports Server (NTRS)

    Lavrukhina, A. K.; Lavrentjeva, Z. A.; Ljul, A. YU.; Ignatenko, K. I.

    1993-01-01

    Olivine inclusions and chondrules of Kainsaz were formed in a unique process of dust matter melting. The elemental abundances of four fractions of olivine (01) inclusions from Kainsaz were analyzed by INAA. The inclusions of fraction A (160 less than d less than 260 microns) have Fe-Ni grains, the inclusions of fractions B (100 less than d less than 160 microns), C (160 less than d less than 260 microns), and D (260 less than d less than 360 microns) do not. The average elemental enrichment factors relative to CI chondrite for each fraction and chondrules of Kainsaz is shown. The enrichment factors of siderophile Co, Ni, Ir, Au, and non-refractory Na in all fractions are less than 1. The factors of refractory Ca, Sc, La, Sm, and Yb are comparative with the corresponding values of O1 aggregates of Allende CV (average 4.76). For chondrules of Kainsaz these values are lower. Fraction A is enriched in Co, Ir, Au, and relative Ni and CI chondrites: Ir greater than Au greater than Co. The values of (Me/Ni)inc/(Me/Ni)CI are equal to 3.25 for Ir, 2.1 for Au, and 1.2 for Co. The superabundances in Ir and Au relative to Ni witness to formation of Fe-Ni grains of O1 inclusions by agglomeration of grains enriched in refractory metal with grains enriched in non-refractory metal (Au). The enrichments of fraction A in Ca, Sc, La, Sm, and Yb witness about presence of high-temperature phases in O1 inclusions.

  15. 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

  16. 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

  17. 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

  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. A secondary origin of chondrule magnetization in the Allende CV carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Carporzen, L.; Fu, R.; Andrade Lima, E.; Weiss, B. P.

    2011-12-01

    Magnetic fields in the solar nebula may have played a key role in the radial transport of angular momentum and mass during the early accretional phase of the solar system. Chondrules and many calcium aluminum inclusions (CAIs), millimeter sized silicate objects found in most chondritic meteorites, were heated to high temperatures and cooled in the nebula and therefore may have recorded a thermoremanent magnetization (TRM) from the nebula field. Additionally, primitive magnetization in chondrules and CAIs may yield constraints about their mode of formation. However, any such primary magnetization may have been significantly altered during subsequent metamorphism and aqueous alteration on the parent asteroid. We performed two tests to determine the nebular origins of remanent magnetization in chondrules and refractory inclusions in the Allende CV3 carbonaceous chondrite: 1) a classic paleomagnetic conglomerate test to identify post-accretional remagnetization events and 2) a unidirectionality test of subsamples taken from individual chondrules and CAIs. We conducted individual measurements of mutually oriented chondrules, CAIs, and matrix as well as SQUID microscope maps of the magnetic fields of 30 μm thin sections. All samples and thin sections were mutually oriented to within 5°. Our results confirm previous findings that all subsamples of the meteorite carry a unidirectional overprint blocked up to 260°-290°C (MT component). Chondrules and CAIs also carry a higher temperature (HT) remanence oriented in scattered directions unrelated to the direction of the MT overprint. We have confirmed that this HT magnetization is not an artifact of the demagnetization procedure but is a preterrestrial component. Measurements of subsamples of single chondrules and CAIs show that the HT magnetization is not unidirectional within each inclusion. Petrographic data suggests that most magnetic minerals in Allende were the product of parent body alteration. These facts suggest

  20. Origin of compact type A refractory inclusions from CV3 carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Simon, S. B.; Davis, A. M.; Grossman, L.

    1999-04-01

    Compact type A (CTA) inclusions are one of the major types of coarse-grained refractory inclusions found in carbonaceous chondrites. They have not been studied in a systematic fashion, leading to some uncertainties and unproven assumptions about their origin. To address this situation, we studied a total of eight CTAs from Allende, Efremovka and Axtell by scanning electron-microscopic and electron and ion-microprobe techniques. These inclusions are very melilite-rich, ranging from ˜60 vol% to nearly monomineralic. Also present are Mg-Al spinel (5-20%), perovskite (trace-˜3%) and, in some samples, Ti-rich (˜17 wt% TiO 2tot) fassaite (trace-˜20%), and rhönite (≤1%). Melilite compositions are mostly between Åk 15 and Åk 40. Chondrite-normalized REE abundance patterns for melilite (flat at ˜10 × CI with positive Eu anomalies) and fassaite (slight HREE enrichment relative to LREE and negative Eu anomalies) are like those for their counterparts in once-molten type B inclusions. The patterns for rhönite have positive slopes from La through Lu and abundances <10 × CI for La and 35-60 × CI for Lu. Features of CTAs that suggest that they were once molten include: rounded inclusion shapes; positively correlated Sc and V abundances in fassaite; radially oriented melilite laths at inclusion rims; and the distribution of trace elements among the phases. Fractional crystallization models show that, with one exception, the REE contents of perovskite and fassaite arose by crystallization of these phases from late, residual liquids that would have resulted from prior crystallization of the observed proportions of melilite and spinel from liquids having the bulk compositions of the inclusions. One Allende CTA (TS32), however, has several features (irregular shape, reversely zoned melilite, fassaite REE contents) that are not readily explained by crystallization from a melt. This inclusion may have undergone little melting and may be dominated by relict grains.

  1. Textural evidence bearing on the origin of isolated olivine crystals in C2 carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Richardson, S. M.; Mcsween, H. Y., Jr.

    1978-01-01

    In some cases the mechanical competence of chondrules in carbonaceous chondrites has been reduced by alteration of their mesostasis glass to friable phyllosilicate, providing a mechanism by which euhedral olivines can be separated from chondrules. Morphological features of isolate olivine grains found in carbonaceous chondrites are similar to those of olivine phenocrysts in chondrules. These observations suggest that the isolated olivine grains formed in chondrules, by crystallization from a liquid, rather than by condensation from a vapor.

  2. 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.

  3. Precursor and metamorphic condition effects on Raman spectra of poorly ordered carbonaceous matter in chondrites and coals

    NASA Astrophysics Data System (ADS)

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

    2009-09-01

    Geothermometers based on Raman spectrometry of carbonaceous matter and covering a wide range of temperatures (100-650 °C) have been developed over recent years. 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 to weak lithostatic pressure and confinement. These results suggest that the use of low temperature carbon thermometers should be restricted to a given geological context. At the same time, the sensitivity of Raman spectra to precursors and certain metamorphic conditions could be used to obtain information other than temperature. The analysis also provides evidence of the accretion of relatively homogeneous PCM precursors among ordinary CO and CV carbonaceous chondrite parent bodies, given that the 514 nm Raman spectra of PCM efficiently trace the

  4. Surface Processes on Small Planetary Bodies: Implications for the Origins of Chondritic Meteorites

    NASA Astrophysics Data System (ADS)

    Akridge, David Glen

    I have conducted both experimental and theoretical work concerning the formation conditions of chondritic meteorites. This work has focused on the size-sorting of chondrules and metal grains, metal abundance in chondrites, gas phase reactions, and the thermal history of meteorite parent bodies containing substantial regoliths. Although many of the major chondritic properties have been assumed to be the result of nebula processes, it is suggested here that the release of volatiles in a parent body regolith would cause gas phase reactions indistinguishable from those occurring in the nebula. The escaping volatiles from either radiogenic 26Al or impact heating could create a dynamic surface dust layer on planetesimals leading to the physical separation of regolith grains of differing size and densities. The thermal history of an H-chondrite parent body (Asteroid 6 Hebe) was numerically modeled using 26Al as the primary heat source. The three layer model consisted of an interior of solid rock overlain by a megaregolith and regolith surfaces coverings. Appropriate porosities, bulk densities, and thermal conductivities were used for each zone. Regolith and megaregolith thicknesses were varied to see which numerical run best matched the metamorphic characteristics of H-chondrites. The results show surprisingly shallow burial depths for most H-chondrites. A moderate 2 km regolith insulates the interior so that H3-6 chondrites can all be formed in the regolith or upper megaregolith. Predicted peak temperatures, cooling rates, and formation time intervals agree well with data obtained from H-chondrites. The release of volatiles (primarily water) during parent body heating events could cause fluidization in the regolith if the upward moving gas flow rate reached a minimum critical velocity. At this minimum velocity particulates are free to move with fluid-like behavior and may segregate based on size and density characteristics. Fluidization experiments at atmospheric and

  5. Isotopic anomalies of noble gases in meteorites and their origins. III - LL-chondrites

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    Nine LL-chondrites were studied by selective etching to characterize the noble gas components in three mineral fractions: HF-HCl-solubles, chromite and carbon. The Ne-20/Ar-36 ratio is considered, noting that chondrites of different petrologic types cannot all be derived from the same volatile rich ancestor, but must have formed over a range of temperatures, with correspondingly different volatile contents. Variations in the carbonaceous chondrite fission (CCFXe) component in LL3, LL5, and LL6 chondrites are discussed, noting that if CCFXe comes from a supernova, then its distribution in LL-chondrites requires three presolar carrier minerals of the right solubility properties, containing three different xenon components. However, if CCFXe comes from fission of a volatile superheavy element, then its decrease from LL3 to LL6 can be attributed to less complete condensation from the solar nebula. Finally, the three types of primordial xenon components which occur in different minerals of the same meteorite are described.

  6. Origin of dark clasts in the Acfer 059/El Djouf 001 CR2 chondrite

    NASA Technical Reports Server (NTRS)

    Endreb, M.; Keil, K.; Bischoff, A.; Speitel, 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.

  7. The Burnwell, Kentucky, Low-FeO chondrite fall: Description, classification and origin

    NASA Astrophysics Data System (ADS)

    Russell, Sara S.; McCoy, Timothy J.; Jarosewich, Eugene; Ash, Richard D.

    1998-07-01

    The Burnwell, Kentucky, meteorite fell as a single stone on 4 September 1990. Burnwell has lower Fa in olivine (15.8 mol%), Fs in orthopyroxene (13.4 mol%), Co in kamacite (0.36 wt.%), FeO from bulk chemical analysis (9.43 wt.%), and (17O (0.51(0.02e), and higher Fe, Ni, Co metal (19.75 wt.% from bulk wet chemical analysis) than observed in H chondrites. Burnwell plots on extensions of H-L-LL chondrite trends for each of these properties towards more reducing compositions than in H chondrites. Extensions of this trend have been previously suggested in the case of other low-FeO chondrites or silicate inclusions in the IIE iron Netscha'vo, but interpretation of the evidence in these meteorites is complicated by terrestrial weathering, chemical disequilibrium or reduction. In contrast, Burnwell is an equilibrated fall that exhibits no evidence for reduction. As such, it provides the first definitive evidence for extension of the H-L-LL ordinary chondrite trend beyond typical H values, towards more reducing compositions.

  8. 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.

  9. The Dresden (Ontario) H6 Chondrite, Part II: Classification Estimated Fireball Trajectory, and Possible Origin

    NASA Astrophysics Data System (ADS)

    McCausland, Phil J. A.; Brown, Peter G.; Wilson, Graham C.

    2006-06-01

    The Dresden (Ontario) meteorite fell in southwestern Ontario on the early evening of July 11, 1939. We re-examine this historic Canadian fall, consider the mineralogy, physical properties, and bulk chemistry of the meteorite, and estimate its trajectory and pre-atmospheric orbit based on visual accounts of the event. Mineralogical examination of several fragments of the meteorite reveals poor definition of chondrule margins, lack of glass, and the presence of minor feldspar, confirming Dresden (Ontario) to be an H6 ordinary chondrite. The bulk of the stone has undergone a low level of shock (S2) as indicated by generally clean extinction of silicate grains. A 12-g bulk sample of the Dresden (Ontario) main mass has elemental abundances that agree well with the H-chondrite average. The bulk density for Dresden (3.48+/-0.07 g/cm3) and porosity (4.9%) are also typical of H chondrites. Several accounts of the fall event constrain the Dresden fireball to have had a ground projection azimuth of ~050, passing from north of London, Ontario southwestwards toward Dresden. The tightly grouped strewnfield of fusion-encrusted fragments recovered ~10 km southwest of Dresden, Ontario suggests that the fireball trajectory was steep. Dark-flight simulations using the 050 azimuth best reproduce the recovered strewnfield distribution with an entry angle of >70°. The range of potential orbits derived from this inferred steep trajectory is consistent with previous orbits measured for meteorite-producing fireballs, and suggest that the Dresden meteoroid had an Apollo asteroid-type orbit, with a perihelion just inside that of the Earth's and a low-to-moderate inclination. The Dresden (Ontario) H6 chondrite is thus petrologically and dynamically similar to other H chondrites with known orbits. A comparison of the known H-chondrite orbits with a modelled debiased distribution of near-Earth objects indicates that the H chondrites were most likely delivered to the Earth via the v6 and the 3

  10. 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.

  11. 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

  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. 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.

  14. The origin of chondrules and chondrites: Debris from low-velocity impacts between molten planetesimals?

    NASA Astrophysics Data System (ADS)

    Sanders, Ian S.; Scott, Edward R. D.

    2012-12-01

    We investigate the hypothesis that many chondrules are frozen droplets of spray from impact plumes launched when thin-shelled, largely molten planetesimals collided at low speed during accretion. This scenario, here dubbed "splashing," stems from evidence that such planetesimals, intensely heated by 26Al, were abundant in the protoplanetary disk when chondrules were being formed approximately 2 Myr after calcium-aluminum-rich inclusions (CAIs), and that chondrites, far from sampling the earliest planetesimals, are made from material that accreted later, when 26Al could no longer induce melting. We show how "splashing" is reconcilable with many features of chondrules, including their ages, chemistry, peak temperatures, abundances, sizes, cooling rates, indented shapes, "relict" grains, igneous rims, and metal blebs, and is also reconcilable with features that challenge the conventional view that chondrules are flash-melted dust-clumps, particularly the high concentrations of Na and FeO in chondrules, but also including chondrule diversity, large phenocrysts, macrochondrules, scarcity of dust-clumps, and heating. We speculate that type I (FeO-poor) chondrules come from planetesimals that accreted early in the reduced, partially condensed, hot inner nebula, and that type II (FeO-rich) chondrules come from planetesimals that accreted in a later, or more distal, cool nebular setting where incorporation of water-ice with high Δ17O aided oxidation during heating. We propose that multiple collisions and repeated re-accretion of chondrules and other debris within restricted annular zones gave each chondrite group its distinctive properties, and led to so-called "complementarity" and metal depletion in chondrites. We suggest that differentiated meteorites are numerically rare compared with chondrites because their initially plentiful molten parent bodies were mostly destroyed during chondrule formation.

  15. 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].

  16. Origin and evolution of prebiotic organic matter as inferred from the Tagish Lake meteorite.

    PubMed

    Herd, Christopher D K; Blinova, Alexandra; Simkus, Danielle N; Huang, Yongsong; Tarozo, Rafael; Alexander, Conel M O'D; Gyngard, Frank; Nittler, Larry R; Cody, George D; Fogel, Marilyn L; Kebukawa, Yoko; Kilcoyne, A L David; Hilts, Robert W; Slater, Greg F; Glavin, Daniel P; Dworkin, Jason P; Callahan, Michael P; Elsila, Jamie E; De Gregorio, Bradley T; Stroud, Rhonda M

    2011-06-10

    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. At least some molecules of prebiotic importance formed during the alteration. PMID:21659601

  17. Origin and Evolution of Prebiotic Organic Matter As Inferred from the Tagish Lake Meteorite

    NASA Astrophysics Data System (ADS)

    Herd, Christopher D. K.; Blinova, Alexandra; Simkus, Danielle N.; Huang, Yongsong; Tarozo, Rafael; Alexander, Conel M. O.'D.; Gyngard, Frank; Nittler, Larry R.; Cody, George D.; Fogel, Marilyn L.; Kebukawa, Yoko; Kilcoyne, A. L. David; Hilts, Robert W.; Slater, Greg F.; Glavin, Daniel P.; Dworkin, Jason P.; Callahan, Michael P.; Elsila, Jamie E.; De Gregorio, Bradley T.; Stroud, Rhonda M.

    2011-06-01

    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. At least some molecules of prebiotic importance formed during the alteration.

  18. 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.; Kebukawa, Yoko; Kilcoyne, A. L.; Hilts, Robert W.; Slater, Greg F.; Glavin, Daniel P.; Dworkin, Jason P.; Callahan, Michael P.; Elsila, Jamie E.; De Gregorio, Bradley T.; Stroud, Rhonda M.

    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.

  19. 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.

  20. 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.

  1. Trace-Element Constraints on Origin of SiO2-bearing Clasts in Ordinary Chondrites

    NASA Astrophysics Data System (ADS)

    Misawa, K.; Kanazawa, M.; Bridges, J. C.; Nakamura, N.; Hutchison, R.

    1995-09-01

    Silica-rich igneous-textured clasts are found in OC [1-6]. The SiO2-bearing clasts found in the Parnallee (LL3.6) and Farmington (L5) chondrites are isotopically unique [4-6]. They plot on a mixing line defined between UOC chondrules and an 16(sub)O-depleted end member in the oxygen three isotope diagram. We analyzed trace elements including REE by MSID technique for SiO2-bearing clasts (CB1, CB4, CB7, and CB8) from Parnallee. Some major and minor elements of CB8 were determined by AA or ICP-AES. The CI-chondrite normalized REE patterns of the clasts are shown in Fig. 1. CB8 has a high Si/Mg ratio (2.5), although its bulk Mg/(Mg + Fe) and Fe/Mn ratios (0.79 and 51, respectively) are within the range of chondritic values. Refractory elements Ca and Al are highly fractionated in CB8; the clast is enriched in Ca (3 x CI) but depleted in Al (0.7 x CI). CB1, CB4, and CB7 also show Ca enrichment (3-7 x CI). CB8 is depleted in moderately volatile lithophiles Mn, Na, K, and Rb (0.18-0.71 x CI), siderophile elements Fe, Co, and Ni (0.0041-0.39 x CI), and chalcophile element Zn (0.076 x CI). The SiO2-bearing clasts analyzed exhibit a gradual depletion from LREE to HREE (CI-normalized La/Lu ratios vary from 1.6 to 18) and a large positive Eu anomaly (Eu/Eu*=2.4-14) along with a depletion of La. This LREE/HREE fractionation is inversely correlated with SiO2 contents of the clasts. Abundance of Sr is parallel to that of Eu in CB8. However, Sr is depleted compared with Eu in the other clasts. These abundance patterns are quite different from those of typical ferromagnesian chondrules in UOCs, SiO2-bearing pyroxene-rich clast in Hedjaz (L3.7) [3], and silica-rich orthopyroxenite Bo-1 in Bovedy (L3) [7]. Absence of metal and sulfide, low abundances of siderophile and chalcophile elements in the clasts imply that metal and sulfide were removed from precursor material before or during clast formation. General REE patterns of SiO2-bearing clasts from Parnallee suggest that they were

  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. The Origin of Non-chondritic HSE Ratios in the Earth's Mantle

    NASA Astrophysics Data System (ADS)

    Laurenz, V.; Rubie, D. C.; Frost, D. J.; Jacobson, S. A.; Morbidelli, A.; Palme, H.; Vogel, A. K.

    2015-12-01

    It is generally thought that Earth's mantle abundances of highly siderophile elements (HSE) were established by the addition of a chondritic late veneer to a mantle that was stripped of HSEs by core formation. A long-standing problem with this hypothesis is that the mantle's suprachondritic Pd/Ir and Ru/Ir ratios cannot be reconciled with any known meteorite group. To address this issue, we modelled the effect of metal-silicate segregation on abundances of the HSE and S in the Earth's mantle by including these elements in a combined accretion/core-formation model. Because in our model only a small fraction of the mantle equilibrates with core-forming metal, the bulk mantle HSE abundances are too large by the end of accretion. Sulfur abundances also greatly exceed S-saturation levels at magma ocean crystallisation temperatures, leading to the formation of a global immiscible sulfide melt that segregated to the core, thus removing HSEs from the mantle [1]. To better constrain the role of sulfide segregation on the HSE budget of the mantle, we experimentally determined the sulfide-silicate partitioning of Pt, Pd, Ru and Ir under high P-T conditions. Results show that Pd and Ru are less chalcophile at pressures above ~20 GPa compared to Pt and Ir, as opposed to the metal-silicate system where Ru is more siderophile than Pt [2]. These results are included in our model, which now involves localized segregation of core-forming metal followed by widespread exsolution and segregation of immiscible sulfide liquids. Platinum and Ir are efficiently extracted from the mantle whereas significant concentrations of Ru and Pd remain. Late veneer addition occurs after sulfide segregation has ceased due to magma ocean solidification. This model reproduces perfectly the non-chondritic Ru/Ir and Pd/Ir ratios of the mantle, reflecting incomplete removal of Ru and Pd from the mantle with core-forming sulfide melts. [1] O'Neill (1991) GCA 55, 1159-1172. [2] Mann et al. (2012) GCA 84, 593-613.

  5. Orbit and dynamic origin of the recently recovered Annama's H5 chondrite

    NASA Astrophysics Data System (ADS)

    Trigo-Rodríguez, Josep M.; Lyytinen, Esko; Gritsevich, Maria; Moreno-Ibáñez, Manuel; Bottke, William F.; Williams, Iwan; Lupovka, Valery; Dmitriev, Vasily; Kohout, Tomas; Grokhovsky, Victor

    2015-05-01

    We describe the fall of Annama meteorite occurred in the remote Kola Peninsula (Russia) close to Finnish border on 2014 April 19 (local time). The fireball was instrumentally observed by the Finnish Fireball Network. From these observations the strewnfield was computed and two first meteorites were found only a few hundred metres from the predicted landing site on 2014 May 29 and 30, so that the meteorite (an H5 chondrite) experienced only minimal terrestrial alteration. The accuracy of the observations allowed a precise geocentric radiant to be obtained, and the heliocentric orbit for the progenitor meteoroid to be calculated. Backward integrations of the orbits of selected near-Earth asteroids and the Annama meteoroid showed that they rapidly diverged so that the Annama meteorites are unlikely related to them. The only exception seems to be the recently discovered 2014UR116 that shows a plausible dynamic relationship. Instead, analysis of the heliocentric orbit of the meteoroid suggests that the delivery of Annama onto an Earth-crossing Apollo-type orbit occurred via the 3:1 mean motion resonance with Jupiter or the nu6 secular resonance, dynamic mechanisms that are responsible for delivering to Earth most meteorites studied so far.

  6. Experimental partial melting of the Allende (CV) and Murchison (CM) chondrites and the origin of asteroidal basalt

    NASA Astrophysics Data System (ADS)

    Jurewicz, A. J. G.; Mittlefehldt, D. W.; Jones, J. H.

    1993-05-01

    Following the investigation of Jurewicz et al. (1991) on the composition of partial melts of eucrites and angrites, this study investigates partial melts of the Allende and Murchison chondrites and details the anhydrous phase relations of both chondrites at 1 atm, under temperatures and oxygen fugacities plausigle for the formation of basaltic meteorites. It was found that, in general, ambient oxygen fugacity exerts a strong influence on the compositions of partial melts of chondrites by controlling the amount of FeO available to the silicate system. At high f(O2), angritic magmas are produced, whereas eucritic melts are produced at low levels of f(O2).

  7. Experimental partial melting of the Allende (CV) and Murchison (CM) chondrites and the origin of asteroidal basalt

    NASA Technical Reports Server (NTRS)

    Jurewicz, A. J. G.; Mittlefehldt, D. W.; Jones, J. H.

    1993-01-01

    Following the investigation of Jurewicz et al. (1991) on the composition of partial melts of eucrites and angrites, this study investigates partial melts of the Allende and Murchison chondrites and details the anhydrous phase relations of both chondrites at 1 atm, under temperatures and oxygen fugacities plausigle for the formation of basaltic meteorites. It was found that, in general, ambient oxygen fugacity exerts a strong influence on the compositions of partial melts of chondrites by controlling the amount of FeO available to the silicate system. At high f(O2), angritic magmas are produced, whereas eucritic melts are produced at low levels of f(O2).

  8. 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.

  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. Molecular study of insoluble organic matter in Kainsaz CO3 carbonaceous chondrite: Comparison with CI and CM IOM .

    NASA Astrophysics Data System (ADS)

    Remusat, L.; Le Guillou, C.; Rouzaud, J.-N.; Binet, L.; Derenne, S.; Robert, F.

    2008-10-01

    Kainsaz CO3 insoluble organic matter (IOM) was studied using Curie point pyrolysis, electronic paramagnetic resonance (EPR), and high-resolution transmission electron microscopy (HRTEM) to determine the effect of thermal metamorphism on molecular chondritic fingerprints. Pyrolysis released a very low amount of products that consist of one- and two-ring aromatic units with methyl, dimethyl, and ethyl substituents. Moreover, Kainsaz IOM contains two orders of magnitude fewer radicals than Orgueil, Murchison, and Tagish Lake IOM. In addition, no diradicaloids were found in Kainsaz, although they are thought to constitute a specific signature for weakly organized extraterrestrial organic compounds in contrast to terrestrial ones. HRTEM reveals a very heterogeneous structure, with microporous disordered carbon, mesoporous graphitic carbons and graphite. Graphitization likely occurs and explains the differences between Kainsaz and CI or CM IOM. Heating stress experienced by Kainsaz IOM, on the parent body and/or prior its accretion, is likely responsible for the differences in molecular and structural organizations compared with those of CI and CM IOM.

  11. 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.

  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. Chondrites and Their Components

    NASA Astrophysics Data System (ADS)

    Scott, E. R. D.; Krot, A. N.

    Chondrites are extraordinary mixtures of materials with diverse origins that formed around other stars, in the solar nebula, and in their parent asteroids. Most chondrites were so severely altered by aqueous fluids, thermal metamorphism, and impacts that the original characteristics of their components have been largely erased. But a few pristine chondrites have preserved an exquisite mineralogical, chemical, isotopic, and chronological record of the first few million years of solar system history. The properties of diverse types of carbonaceous, ordinary, and enstatite chondrites focusing on the most pristine samples are reviewed to establish the chemical, isotopic, and mineralogical properties and origins of their components and to elucidate the asteroidal processes that modified them. Refractory inclusions - amoeboid olivine aggregates and Ca-Al-rich inclusions - were the first solids to form in the solar nebula near to the protosun. Chondrules and associated metallic Fe-Ni grains were still forming several million years later when the earliest planetesimals, which melted due to heat from 26Al decay, were colliding. In the least-altered chondrites, matrix material, which coats chondrules and other components, is largely composed of micrometer-sized silicates and amorphous materials, which formed at high temperatures, plus small amounts (up to 200 ppm) of presolar oxides and silicates.

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

    NASA Astrophysics Data System (ADS)

    Kornacki, A. S.; Fegley, B.

    1984-02-01

    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.

  15. 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.

  16. Characterizing the origins of atmospheric particulate matter

    NASA Astrophysics Data System (ADS)

    Wagstrom, Kristina Michelle

    When developing policy targeted at decreasing air pollution, it is essential that we have a strong understanding of when and where the pollution originated. Towards this goal, we have implemented and evaluated two different source attribution schemes in PMCAMx, a three-dimensional atmospheric chemical transport model. The two schemes, an online (OPSA) and offline version (PSAT), are both designed for computational efficiency and the ability to track source contributions to primary and secondary particulate matter. The two versions showed good agreement with each other and with more accurate, computationally demanding methods. The off-line algorithm (Particulate Source Apportionment Technology, PSAT) is simpler to implement, has a lower computational cost and is suitable for a range of source apportionment studies. We have utilized this algorithm to study the age distribution of atmospheric particulate matter mass in space and time. The average calculated ages are on the order of a few days for particulate matter near the ground, but are highly variable in space and time. Primary aerosol species had average ages of approximately 24 hours over this polluted continental region while the average ages for secondary species were 48-72 hours near the surface. As expected, the average age of all aerosol components increases vertically in the atmosphere. Age increases rapidly away from the sources of aerosol and its precursors and for non-volatile species it increases with particle size. PSAT is an excellent tool for the study of source-receptor relationships. We have studied the extent of pollutant transport in the Eastern United States using two approaches. The first PSAT-based approach is focused on source regions and the second is focused on receptor regions. For the source region focused approach, transport of pollutants is quantified by tracking the emissions from these regions. For the receptor region focused approach, PSAT tracks the pollutants emitted from a series

  17. Extraterrestrial chromite distribution across the mid-Ordovician Puxi River section, central China: Evidence for a global major spike in flux of L-chondritic matter

    NASA Astrophysics Data System (ADS)

    Cronholm, Anders; Schmitz, Birger

    2010-07-01

    Previous studies of mid-Ordovician limestone in Sweden have shown that over a stratigraphic interval representing a few million years there is a two orders-of-magnitude enrichment in fossil L-chondritic meteorites (Ø = 1-21 cm) and sediment-dispersed extraterrestrial chromite (EC) grains (>63 μm). This has been interpreted as a dramatic increase in the flux of L-chondritic matter to Earth following the breakup of the L-chondrite parent body, which based on Ar-Ar gas retention ages (470 ± 6 Ma) of recently fallen meteorites occurred at about this time. Here we show that the general trend in the distribution of sediment-dispersed EC grains can be reproduced in the Puxi River section in central China. A total of 288 kg of limestone was searched for chrome spinels. In samples spanning the lower 8 m of the section, representing the Paroistodus originalis and Lenodus antivariabilis conodont zones, a total of 110 kg of limestone yielded only one EC grain. Similarly to the Swedish sections, EC grains begin to be common in the overlying L. variabilis Zone and remain common throughout the upper 9 m of the section, representing the L. variabilis, Yangtzeplacognathus crassus and L. pseudoplanus zones. In this part of the section 178 kg of limestone yielded 290 EC grains, with an average chemical composition very similar to chromite from recent L chondrites. In most of the beds over this interval one finds 1-4 EC grains per kilogram rock, a clear two orders-of-magnitude enrichment relative to the lower part of the section. Small bed-by-bed variations in the EC content over the upper interval most likely reflect small variations in sedimentation rates. The Puxi River section contains only very rare terrestrial chrome spinel grains, which can be distinguished already by their rounded, abraded appearance compared to the angular, pristine extraterrestrial spinels. In the mid-Ordovician, based on paleoplate reconstructions, the Puxi River site was positioned at mid-latitudes on

  18. Lunar and Planetary Science XXXV: Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The titles in this section include: 1) A Quantitative NMR Analysis of Phosphorus in Carbonaceous and Ordinary Chondrites; 2) An Infrared Study of the Matrices of CI1 and CM2 Chondrites; 3) A Study of the Morphology, Composition and Mineral Associations of Fe-Ni Sulphides in CM Carbonaceous Chondrites; 4) Aqueous Alteration Mineralogy in CM Carbonaceous Chondrites; 5) In Situ Location and Characterization of Carbon-bearing Phases in Carbonaceous; 6) Chondrites: Insights from Yamato 791198, a Weakly-altered CM2 Chondrite; 7) Unique Texture in EET 83389: Clues to Formation of Fine Grained Rims in CM Chondrites; 8) Amoeboid Olivine Aggregates in the NWA 760 CV3 Chondrite; 9) Petrologic Type of CV3 Chondrites as Revealed by Raman Spectroscopy of Organic Matter; 10) A First Look at Acfer 324: Evidence for Another CR 3 Chondrite? 11) Hydrogen Isotopic Composition of the Bencubbin Meteorite; 12) The Fountain Hills Meteorite: A New CBa Chondrite from Arizona; 13) Shock Effects in the Metal-rich Chondrites QUE 94411, Hammadah al Hamra 237 and Bencubbin; 14) Mineralogy and Petrology of Al-rich Objects in the CH Carbonaceous Chondrite North West Africa 739.

  19. Organic matter matters for ice nuclei of agricultural soil origin

    NASA Astrophysics Data System (ADS)

    Tobo, Y.; DeMott, P. J.; Hill, T. C. J.; Prenni, A. J.; Swoboda-Colberg, N. G.; Franc, G. D.; Kreidenweis, S. M.

    2014-04-01

    Heterogeneous ice nucleation is a~crucial process for forming ice-containing clouds and subsequent ice-induced precipitation. The importance for ice nucleation of airborne desert soil dusts composed predominantly of minerals is relatively well understood. On the other hand, the potential influence of agricultural soil dusts on ice nucleation has been poorly recognized, despite recent estimates that they may account for up to ∼25% of the global atmospheric dust load. We have conducted freezing experiments with various dusts, including agricultural soil dusts derived from the largest dust source region in North America. Here we show evidence for the significant role of soil organic matter (SOM) in particles acting as ice nuclei (IN) under mixed-phase cloud conditions. We find that the ice nucleating ability of the agricultural soil dusts is similar to that of desert soil dusts, but is reduced to almost the same level as that of clay minerals (e.g., kaolinite) after either H2O2 digestion or dry heating to 300 °C. In addition, based on chemical composition analysis, we show that organic-rich particles are more important than mineral particles for the ice nucleating ability of the agricultural soil dusts at temperatures warmer than about -36 °C. Finally, we suggest that such organic-rich particles of agricultural origin (namely, SOM particles) may contribute significantly to the ubiquity of organic-rich IN in the global atmosphere.

  20. Organic matter matters for ice nuclei of agricultural soil origin

    NASA Astrophysics Data System (ADS)

    Tobo, Y.; DeMott, P. J.; Hill, T. C. J.; Prenni, A. J.; Swoboda-Colberg, N. G.; Franc, G. D.; Kreidenweis, S. M.

    2014-08-01

    Heterogeneous ice nucleation is a crucial process for forming ice-containing clouds and subsequent ice-induced precipitation. The importance for ice nucleation by airborne desert soil dusts composed predominantly of minerals is widely acknowledged. However, the potential influence of agricultural soil dusts on ice nucleation has been poorly recognized, despite recent estimates that they may account for up to 20-25% of the global atmospheric dust load. We have conducted freezing experiments with various dusts, including agricultural soil dusts derived from the largest dust-source region in North America. Here we show evidence for the significant role of soil organic matter (SOM) in particles acting as ice nuclei (IN) under mixed-phase cloud conditions. We find that the ice-nucleating ability of the agricultural soil dusts is similar to that of desert soil dusts, but is clearly reduced after either H2O2 digestion or dry heating to 300 °C. In addition, based on chemical composition analysis, we demonstrate that organic-rich particles are more important than mineral particles for the ice-nucleating ability of the agricultural soil dusts at temperatures warmer than about -36 °C. Finally, we suggest that such organic-rich particles of agricultural origin (namely, SOM particles) may contribute significantly to the ubiquity of organic-rich IN in the global atmosphere.

  1. 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).

  2. 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.

  3. 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. PMID:11542930

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

    PubMed

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

    1999-01-01

    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 carbon sources 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. PMID:11543335

  5. RECENT DEVELOPMENTS ON THE ORIGIN OF MINERAL MATTER IN COAL.

    USGS Publications Warehouse

    Cecil, C.B.; Stanton, R.W.; Dulong, F.T.; Ruppert, L.P.

    1983-01-01

    This study attempts to quantify some of the various origins of mineral matter. Data developed for the Upper Freeport coal bed indicates that mineral matter other than pyrite and calcite is primarily derived from the vegetal matter that ultimately became coal. Cathodoluminesence was used to verify that the quartz in the Upper Freeport coal is dominantly authigenic and not detrital in origin. Sulfur variability in coal beds of the central Appalachian Basin was investigated stratagraphically.

  6. Thermal history of type-3 chondrites in the NASA antarctic collection

    NASA Astrophysics Data System (ADS)

    Bonal, L.; Quirico, E.; Montagnac, G.

    2014-07-01

    Chondrites are the most primitive meteorites. However, they were all modified in some ways by post-accretion geological processes operating on their asteroidal parent bodies. Hence, to decipher the formation(s) and origin(s) of their components, we must first understand how chondritic materials were modified in their asteroidal parent bodies. The modifications induced by secondary processes should not be underestimated and have to be precisely estimated before any interpretation of chondrite properties in terms of cosmochemistry. In particular, all chondrites contain some organic components that were potentially chemically and physically modified through post-accretion processes. A thin understanding of the induced evolution is required to allow for pertinent comparisons with other primitive extraterrestrial materials, such as cometary grains, to finally address questions such as the origin of organics in the Solar System. Type 3 chondrites experienced thermal metamorphism on their asteroidal parent body due to the radioactive decay of elements such as ^{26}Al. Temperatures higher than 300 °C were experienced on timescales of several thousands of years. Still, type 3 chondrites remain as unequilibrated rocks and common mineralogical thermometers cannot be applied. The polyaromatic carbonaceous matter is sensitive to thermal episodes (of long and short duration) experienced by the host meteorite. In particular, its structural order directly reflects the thermal history experienced on their parent bodies. The structural modification of the aromatic carbonaceous matter towards a higher order is irreversible, and independent of the mineralogy and degree of aqueous alteration. It is mainly controlled by the peak metamorphic temperature. Moreover, under the assumption of fairly similar organic precursors among chondrites of distinct groups, the structural order of polyaromatic organic matter allows for a direct comparison of their metamorphic grades. It is then possible

  7. 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.

  8. 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.

  9. 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.

  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. 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.

  12. Chondrites and the Protoplanetary Disk, Part 4

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Topics discussed include: Cosmochemical fractionations, Chondritic meteorites and their components, Jet flows: Formation and thermal processing of solids in protoplanetary disks, A Search for Solar-System processing signatures in presolar grains, Experimental study of iron metal condensation, The chondrite types and their origins, Spinel-rich spherules from murchison, etc.

  13. The Bencubbin chondrite breccia and its relationship to CR chondrites and the ALH85085 chondrite

    NASA Astrophysics Data System (ADS)

    Weisberg, Michael K.; Nehru, Cherukupalli E.; Prinz, Martin

    1990-12-01

    Bencubbin is an unclassified meteorite breccia which consists mainly of host silicate (˜40 vol.%) and host metal (˜60%) components. Rare (<1%) ordinary chondrite clasts and a dark xenolith (formerly called a carbonaceous chondrite clast) are also found. A petrologic study of the host silicates shows that they have textures, modes, mineralogy and bulk compositions that are essentially the same as that of barred olivine (BO) chondrules, and they are considered to be BO chondritic material. Bulk compositions of individual host silicate clasts are identical and differ only in their textures which are a continuum from coarsely barred, to finely barred, to feathery microcrystalline; these result from differing cooling rates. The host silicates differ from average BO chondrules only in being angular clasts rather than fluid droplet-shaped objects, and in being larger in size (up to 1 cm) than most chondrules; but large angular to droplet-shaped chondrules occur in many chondrites. Bencubbin host metallic FeNi clasts have a positive Ni-Co trend, which coincides with that of a calculated equilibrium nebular condensation path. This appears to indicate a chondritic, rather than impact, origin for this component as well. The rare ordinary chondrite clast and dark xenolith also contain FeNi metal with compositions similar to that of the host metal. Two scenarios are offered for the origin of the Bencubbin breccia. One is that the Bencubbin components are chondritic and were produced in the solar nebula. Later brecciation, reaggregation and minor melting of the chondritic material resulted in it becoming a monomict chondritic breccia. The alternative scenario is that the Bencubbin components formed as a result of major impact melting on a chondritic parent body; the silicate fragments were formed from an impact-induced lava flow and are analogous to the spinifex-textured rocks characteristic of terrestrial . Both scenarios have difficulties, but the petrologic, chemical and

  14. Inert scalar doublet asymmetry as origin of dark matter

    NASA Astrophysics Data System (ADS)

    Dhen, Mikaël; Hambye, Thomas

    2015-10-01

    In the inert scalar doublet framework, we analyze what would be the effect of a B -L asymmetry that could have been produced at high temperature in the thermal bath of the Universe. We show that unless the "λ5" scalar interaction is tiny, this asymmetry is automatically reprocessed in part into an inert scalar asymmetry that could be at the origin of dark matter today. Along this scenario, the inert mass scale lies in the few-TeV range, and direct detection constraints require that the inert scalar particles decay into a lighter dark matter particle which, as the inert doublet, is odd under a Z2 symmetry.

  15. Petrology of types 4-6 carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    A comparative mineralogic study has been made of Coolidge, Karoonda, and new C4 chondrites in order to clarify the origin of C4-6 chondrites. It is shown that the properties of all C4-6 chondrites are consistent with an origin by metamorphism of C3-like precursors by processes analogous to those operating in ordinary chondrite parent bodies or planetesimals. However, type 4-6 material was not well mixed with type 3 material in the CV3 parent body. It is concluded that C4-6 chondrites may come from one or more separate parent bodies.

  16. 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.

  17. 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.

  18. The origin of ambient particulate matter concentrations in the Netherlands

    NASA Astrophysics Data System (ADS)

    Hendriks, Carlijn; Kranenburg, Richard; Kuenen, Jeroen; van Gijlswijk, René; Wichink Kruit, Roy; Segers, Arjo; Denier van der Gon, Hugo; Schaap, Martijn

    2013-04-01

    Particulate matter poses a significant threat to human health. To be able to develop effective mitigation strategies, the origin of particulate matter needs to be established. The regional air quality model LOTOS-EUROS, equipped with a newly developed labeling routine, was used to establish the origin of PM10 and PM2.5 in the Netherlands for 2007-2009 at the source sector level, distinguishing between national and foreign sources. The results suggest that 70-80% of modeled PM10 and 80-95% of PM2.5 in the Netherlands is of anthropogenic origin. About 1/3 of anthropogenic PM10 is of Dutch origin and 2/3 originates in foreign countries. Agriculture and transport are the Dutch sectors with the largest contribution to PM10 mass in the Netherlands, whereas the foreign contribution is more equally apportioned to road transport, other transport, industry, power generation and agriculture. For the PM2.5 fraction, a larger share is apportioned to foreign and anthropogenic origin than for PM10, but the same source sectors are dominant. The national contribution to PM levels is significantly higher in the densely populated Randstad area than for the country on average and areas close to the borders. In general, the Dutch contribution to the concentration of primary aerosol is larger than for secondary species. The sectoral origin varies per component and is location and time dependent. During peak episodes, natural sources are less important than under normal conditions, whereas especially road transport and agriculture become more important.

  19. 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].

  20. 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

  1. 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.

  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. PMID:22794298

  4. Investigating the Origins of Dark Matter Halo Density Profiles

    NASA Astrophysics Data System (ADS)

    Williams, Liliya L. R.; Babul, Arif; Dalcanton, Julianne J.

    2004-03-01

    Although high-resolution N-body simulations make robust empirical predictions of the density distribution within cold dark matter halos, these studies have yielded little physical insight into the origins of the distribution. We therefore attempt to investigate the problem using analytic and semianalytic approaches. Simple analytic considerations suggest that the inner slope of the central cusps in dark matter halos cannot be steeper than α=2 (where ρ~r-α), with α=1.5-1.7 being a more realistic upper limit. Moreover, our analysis suggests that any number of effects, whether real (e.g., angular momentum imparted by tidal torques and secondary perturbations) or artificial (e.g., two-body interactions, the accuracy of the numerical integrator, round-off errors) will result in shallower slopes. We also find that the halos should exhibit a well-defined relationship between rperi/rapo and jθ/jr. We derive this relationship analytically and speculate that it may be ``universal.'' Using a semianalytic scheme based on Ryden & Gunn, we further explore the relationship between the specific angular momentum distribution in a halo and its density profile. For present purposes, we restrict ourselves to halos that form primarily via the nearly smooth accretion of matter, and consider only the specific angular momentum generated by secondary perturbations associated with the cold dark matter spectrum of density fluctuations. Compared to those formed in N-body simulations, our ``semianalytic'' halos are more extended, have flatter rotation curves, and have a higher specific angular momentum, even though we have not yet taken into account the effects of tidal torques. Whether the density profile of numerical halos is indeed the result of loss in angular momentum outside the central region, and whether this loss is a feature of hierarchical merging and major mergers in particular, is under investigation.

  5. 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

  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. Do We Already have Samples of Ceres? H Chondrite Halites and the Ceres-Hebe Link

    NASA Astrophysics Data System (ADS)

    Fries, M.; Messenger, S.; Steele, A.; Zolensky, M.

    2013-09-01

    We investigate the hypothesis that halites in the H chondrites Zag and Monahans originate from Ceres. Evidence includes mineralogy of the halites and orbital simularities between 1 Ceres and the purported H chondrite parent body 6 Hebe.

  8. 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).

  9. 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

  10. 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.

  11. 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.

  12. The Linum chondrite

    NASA Astrophysics Data System (ADS)

    Matthes, J.; Adam, K.

    1988-12-01

    Based on optical microscopy and electron microprobe analysis, the Linum (East Germany) chondrite is classified as an L6b chondrite that contains olivine (Fa24), orthopyroxene (Fs20), clinopyroxene (Wo45En47Fs8), plagioclase (An10Ab84Or6), nickel-iron, troilite, chromite and accessory amounts of chlorapatite and whitlockite.

  13. 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.

  14. 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

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

    PubMed

    Canetti, Laurent; Drewes, Marco; Shaposhnikov, Mikhail

    2013-02-01

    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. PMID:23432234

  16. 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

  17. Micron-scale D/H heterogeneity in chondrite matrices: A signature of the pristine solar system water?

    NASA Astrophysics Data System (ADS)

    Piani, Laurette; Robert, François; Remusat, Laurent

    2015-04-01

    Organic matter and hydrous silicates are intimately mixed in the matrix of chondrites and in-situ determination of their individual D/H ratios is therefore challenging. Nevertheless, the D/H ratio of each pure component in this mixture should yield a comprehensible signature of the origin and evolution of water and organic matter in our solar system. We measured hydrogen isotope ratios of organic and hydrous silicates in the matrices of two carbonaceous chondrites (Orgueil CI1 and Renazzo CR2) and one unequilibrated ordinary chondrite (Semarkona, LL3.0). A novel protocol was adopted, involving NanoSIMS imaging of H isotopes of monoatomatic (H-) and molecular (OH-) secondary ions collected at the same location. This allowed the most enriched component with respect to D to be identified in the mixture. Using this protocol, we found that in carbonaceous chondrites the isotopically homogeneous hydrous silicates are mixed with D-rich organic matter. The opposite was observed in Semarkona. Hydrous silicates in Semarkona display highly heterogeneous D/H ratios, ranging from 150 to 1800 ×10-6 (δDSMOW = - 40 to 10 600‰). Organic matter in Semarkona does not show such large isotopic variations. This suggests limited isotopic exchange between the two phases during aqueous alteration. Our study greatly expands the range of water isotopic values measured so far in solar system objects. This D-rich water reservoir was sampled by the LL ordinary chondrite parent body and an estimate (≤9%) of its relative contribution to the D/H ratio of water in Oort cloud family comets is proposed.

  18. Carbon isotopes in bulk carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Halbout, J.; Mayeda, T. K.; Clayton, R. N.

    1985-01-01

    The chemical and physical processes involved in the formation of the solar system are examined. Primitive matter has been found on a microscopic scale in a variety of meteorites: fragments of small solar system bodies that were never part of a large planet. This primitive matter has, in most cases, been identified by the presence of anomalous abundances of some isotopes of the chemical elements. Of particular interest for carbon isotope studies are the primitive meteorites known as carbonaceous chondrites. Using a selective oxidation technique to sort out the carbon contained in different chemical forms (graphite, carbonates, and organic matter), four carbonaceous chondrites are analyzed. The presence of the (13) C-rich component was confirmed and additional carbon components with different, but characteristic, isotopic signatures were resolved.

  19. On The Origin of Light Dark Matter Species

    SciTech Connect

    Essig, Rouven; Kaplan, Jared; Schuster, Philip; Toro, Natalia; /Stanford U., Phys. Dept.

    2010-06-04

    TeV-mass dark matter charged under a new GeV-scale gauge force can explain electronic cosmic-ray anomalies. We propose that the CoGeNT and DAMA direct detection experiments are observing scattering of light stable states 'GeV-Matter' that are charged under this force and constitute a small fraction of the dark matter halo. Dark higgsinos in a supersymmetric dark sector are natural candidates for GeV-Matter that scatter off protons with a universal cross-section of 5 x 10{sup -38} cm{sup 2} and can naturally be split by 10-30 keV so that their dominant interaction with protons is down-scattering. As an example, down-scattering of an O(5) GeV dark higgsino can simultaneously explain the spectra observed by both CoGeNT and DAMA. The event rates in these experiments correspond to a GeV-Matter abundance of 0.2-1% of the halo mass density. This abundance can arise directly from thermal freeze-out at weak coupling, or from the late decay of an unstable TeV-scale WIMP. Our proposal can be tested by searches for exotics in the BaBar and Belle datasets.

  20. 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.

  1. 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.

  2. The D/H Ratio in Chondrites

    NASA Astrophysics Data System (ADS)

    Robert, François

    2003-04-01

    The statistical distribution of all available published D/H ratios of carbonaceous chondrites is presented. The possible interpretations of this distribution are reviewed at the global scale of the solar system planetary objects and at the scale defined by the carbonaceous meteorites. New issues concerning the chemical origin of the deuterium enrichment in solar system water and organic molecules are put into light by this exercise. This distribution is a robust constraint on the origin of water on Earth.

  3. 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

  4. 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.

  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. 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

  7. Halogens in CM Chondrites

    NASA Astrophysics Data System (ADS)

    Menard, J. M.; Caron, B.; Jambon, A.; Michel, A.; Villemant, B.

    2013-09-01

    We set up an extraction line of halogens (fluorine, chlorine) by pyrohydrolysis with 50 mg of rock. We analyzed 7 CM2 chondrites found in Antarctica and found that the Cl content of meteorites with an intact fusion crust is higher than those without.

  8. Nitrogen in chondritic metal

    NASA Astrophysics Data System (ADS)

    Mathew, K. J.; Marti, K.; Kim, Y.

    2005-02-01

    We report new nitrogen isotopic data in metals of H-, L- and one LL -chondrites, with N abundances in the range of ˜0.3 to 3.3 ppm and half of these <1 ppm. Nitrogen isotopic signatures in metals with low indigenous N concentrations are modified by cosmic ray spallation components; corrections are required to determine the indigenous N signatures. The metals of type 4 and 5 show uniform indigenous nitrogen (δ 15N = -6.8 ± 0.5 ‰) and confirm a reported possible genetic association of chondritic metal with metal in IIE and IVA iron meteorites. Distinct isotopic signatures are observed in two metal samples of the Portales Valley (H6) meteorite which both are inconsistent with signatures in H4 and H5 chondrites, but possibly reveal a record of impact-induced melting and metamorphism on the parent asteroid. Anomalous nitrogen signatures in metals of type 3 chondrites, on the other hand, may reflect residues of surviving presolar isotopic signatures.

  9. 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

  10. 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.

  11. Thermal evolution and sintering of chondritic planetesimals. III. Modelling the heat conductivity of porous chondrite material

    NASA Astrophysics Data System (ADS)

    Henke, Stephan; Gail, Hans-Peter; Trieloff, Mario

    2016-04-01

    Context. The construction of models for the internal constitution and temporal evolution of large planetesimals, which are the parent bodies of chondrites, requires as accurate as possible information on the heat conductivity of the complex mixture of minerals and iron metal found in chondrites. The few empirical data points on the heat conductivity of chondritic material are severely disturbed by impact-induced microcracks modifying the thermal conductivity. Aims: We attempt to evaluate the heat conductivity of chondritic material with theoretical methods. Methods: We derived the average heat conductivity of a multi-component mineral mixture and granular medium from the heat conductivities of its mixture components. We numerically generated random mixtures of solids with chondritic composition and packings of spheres. We solved the heat conduction equation in high spatial resolution for a test cube filled with such matter. We derived the heat conductivity of the mixture from the calculated heat flux through the cube. Results: For H and L chondrites, our results are in accord with empirical thermal conductivity at zero porosity. However, the porosity dependence of heat conductivity of granular material built from chondrules and matrix is at odds with measurements for chondrites, while our calculations are consistent with data for compacted sandstone. The discrepancy is traced back to subsequent shock modification of the currently available meteoritic material resulting from impacts on the parent body over the last 4.5 Ga. This causes a structure of void space made of fractures/cracks, which lowers the thermal conductivity of the medium and acts as a barrier to heat transfer. This structure is different from the structure that probably exists in the pristine material where voids are represented by pores rather than fractures. The results obtained for the heat conductivity of the pristine material are used for calculating models for the evolution of the H chondrite

  12. Thermal evolution and sintering of chondritic planetesimals. III. Modelling the heat conductivity of porous chondrite material

    NASA Astrophysics Data System (ADS)

    Henke, Stephan; Gail, Hans-Peter; Trieloff, Mario

    2016-05-01

    Context. The construction of models for the internal constitution and temporal evolution of large planetesimals, which are the parent bodies of chondrites, requires as accurate as possible information on the heat conductivity of the complex mixture of minerals and iron metal found in chondrites. The few empirical data points on the heat conductivity of chondritic material are severely disturbed by impact-induced microcracks modifying the thermal conductivity. Aims: We attempt to evaluate the heat conductivity of chondritic material with theoretical methods. Methods: We derived the average heat conductivity of a multi-component mineral mixture and granular medium from the heat conductivities of its mixture components. We numerically generated random mixtures of solids with chondritic composition and packings of spheres. We solved the heat conduction equation in high spatial resolution for a test cube filled with such matter. We derived the heat conductivity of the mixture from the calculated heat flux through the cube. Results: For H and L chondrites, our results are in accord with empirical thermal conductivity at zero porosity. However, the porosity dependence of heat conductivity of granular material built from chondrules and matrix is at odds with measurements for chondrites, while our calculations are consistent with data for compacted sandstone. The discrepancy is traced back to subsequent shock modification of the currently available meteoritic material resulting from impacts on the parent body over the last 4.5 Ga. This causes a structure of void space made of fractures/cracks, which lowers the thermal conductivity of the medium and acts as a barrier to heat transfer. This structure is different from the structure that probably exists in the pristine material where voids are represented by pores rather than fractures. The results obtained for the heat conductivity of the pristine material are used for calculating models for the evolution of the H chondrite

  13. 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

  14. 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.

  15. The origin and biogeochemistry of organic matter in surface sediments of Lake Shihwa and Lake Hwaong

    NASA Astrophysics Data System (ADS)

    Won, Eun-Ji; Cho, Hyen-Goo; Shin, Kyung-Hoon

    2007-12-01

    To understand the origin and biogeochemistry of the organic matter in surface sediments of Lake Shihwa and Lake Hwaong, organic nitrogen, inorganic nitrogen, labile organic carbon, and residual organic carbon contents as well as stable isotope ratios for carbon and nitrogen were determined by KOBr-KOH treatment. Ratios of organic carbon to organic nitrogen (Corg/Norg) (mean = 24) were much higher than ratios of organic carbon to total nitrogen (Corg/Ntot) (mean=12), indicating the presence of significant amounts of inorganic nitrogen in the surface sediments of both lakes. Stable isotope ratios for organic nitrogen were, on average, 5.2‰ heavier than ratios of inorganic nitrogen in Lake Shihwa, but those same ratios were comparable in Lake Hwaong. This might be due to differences in the origin or the degree of degradation of sedimentary organic matter between the two lakes. In addition, stable isotope ratios for labile organic carbon were, on average, 1.4‰ heavier than those for residual organic carbon, reflecting the preferential oxidation of13C-enriched organic matter. The present study demonstrates that KOBr-KOH treatment of sedimentary organic matter can provide valuable information for understanding the origin and degradation state of organic matter in marine and brackish sediments. This also suggests that the ratio of Corg/Norg and stable isotope ratios for organic nitrogen can be used as indexes of the degree of degradation of organic matter.

  16. Compositions, geochemistry, and shock histories of recrystallized LL chondrites

    NASA Astrophysics Data System (ADS)

    Friedrich, Jon M.; Perrotta, Grace C.; Kimura, Makoto

    2014-08-01

    To examine compositional changes associated with high degrees of apparent thermal metamorphism among the LL chondrites, we have examined seven LL chondrites originally classified as being petrographic type 7. For comparison, we also analyzed the L6/7 chondrite Y-790124. We found that A-880933 is actually an LL4-6 genomict breccia and Y-790124 is best described as an L6 (S3) chondrite. The remaining six chondrites (EET 92013, Uden, Y-74160, Y-790144, Y-791067, Y-82067) are clearly of LL provenance, and each experienced temperatures high enough for them to have been recrystallized. In four of these samples (EET 92013, Uden, Y-74160, Y-790144) we find elemental patterns suggesting Fe(Ni)-FeS mobilization. Others (Y-791067, Y-82067) have compositions identical to average equilibrated LL chondrites. From our compositional data, we infer that EET 92013, Uden, Y-74160, Y-790144 experienced very low degrees of partial melting prior to recrystallization, but Y-791067 and Y-82067 experienced isochemical solid state recrystallization. The heat source responsible for the high degrees of thermal alteration of these meteorites is limited to either the decay of now extinct radionuclides (26Al) or impact-related heating. To evaluate the nature of the heat source, we use 40Ar-39Ar literature data and petrographic examinations to infer the cooling history and shock history of these chondrites. We find that heating due to impact is the most likely heat source for the heating of the recrystallized chondrites. The potential impacts occurred well after the initial stages of LL chondrite thermal metamorphism, but still early in the LL parent body’s history, probably ∼4.2-4.3 Ga ago. These rocks experienced mild shock histories following their recrystallization.

  17. 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.

  18. 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.

  19. 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

    2006-05-01

    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. PMID:16675696

  20. Thermal history modelling of the H chondrite parent body

    NASA Astrophysics Data System (ADS)

    Henke, S.; Gail, H.-P.; Trieloff, M.; Schwarz, W. H.; Kleine, T.

    2012-09-01

    Context. The cooling histories of individual meteorites can be empirically reconstructed by using ages obtained from different radioisotopic chronometers having distinct closure temperatures. For a given group of meteorites derived from a single parent body such data permit the detailed reconstruction of the cooling history of that body. Particularly suited for this purpose are H chondrites because (i) all of them are thought to derive from a single parent body (possibly asteroid (6) Hebe) and (ii) for several specimens precise radiometric ages over a wide range of closure temperatures are available. Aims: A thermal evolution model for the H chondrite parent body is constructed by using the cooling histories of all H chondrites for which at least three different precise radiometric ages are available. The thermal model thus obtained is then used to constrain some important basic properties of the H chondrite parent body. Methods: Thermal evolution models are calculated using our previously developed code, which incorporates the effects of sintering and uses new thermal conductivity data for porous materials. Several key parameters determining the thermal evolution of the H chondrite parent body are varied together with the unknown original location of the H chondrites within their parent body until an optimal fit between the radiometric age data and the properties of the model is obtained. The fit is performed in an automated way based on an "evolution algorithm" to allow for a simultaneous fit of a large number of data, which depend in a complex way on several parameters. Empirical data for the cooling history of H chondrites are taken from the literature and the thermal model is optimised for eight samples for which radiometric ages are available for at least three different closure temperatures. Results: A set of parameters for the H chondrite parent body is found that yields excellent agreement (within error bounds) between the thermal evolution model and

  1. Disentangling nebular and asteroidal features of CO3 carbonaceous chondrite meteorites

    NASA Technical Reports Server (NTRS)

    Scott, Edward R. D.; Jones, Rhian H.

    1990-01-01

    Ten carbonaceous CO3 chondrites (including four chondrites from Antarctica and the Colony, Isna, Kainsaz, Lance , Ornans, and Warrenton chondrites) were analyzed with respect to mean compositions of olivines and low-Ca pyroxenes in order to distinguish the primary nebular features of these chondrites from the secondary (asteroidal or nebular) features. In three of the Antarctic chondrites, matrices and metal grains were analyzed in order to investigate the origin of mineralogical trends in the CO3 sequence. Based on these results, the CO3 chondrites were classified into subtypes 3.0-3.7. In the silicates of chondrites ALH A77307 and Colony, classified as type 3.0, metamorphic effects appear to be absent. Chemical and mineralogical studies suggest that the type 3.1 to 3.7 CO chondrites represent a metamorphic sequence that formed from material closely resembling type 3.0 CO chondrites by metamorphism in one or more planetesimals or asteroids, not by interactions between chondritic ingredients in the solar nebula.

  2. The asteroidal source region of ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Wetherill, G. W.

    1984-01-01

    The final, Earth-impacting orbits of ordinary chondritic meteorites have a very special distribution. By use of visual radiant and time of fall data, as well as photographic fireball orbits (1) it is inferred that chondrite perihelia are concentrated near 1 A.U., eccentricities are usually rather high (approximately 0.5), and inclinations are low (approximately 10 deg). Velocity selection resulting from atmospheric ablation plays a significant role in determining this orbital distribution, but by no means suffices to explain it. The observed distribution is a fragile one, and can easily be destroyed by Earth and Venus perturbations. This places severe constraints on the location of the original source bodies, of which these meteorites are fragments. New calculations were made of the expected distribution of final orbits from a range of initial sources, taking into consideration close encounter planetary perturbations, secular resonance, destruction by collision in space, and atmospheric ablation.

  3. 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.

  4. 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.

  5. 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.

  6. Mars as the Parent Body for the CI Carbonaceous Chondrites: Confirmation of Early Mars Biology

    NASA Astrophysics Data System (ADS)

    Brandenburg, J. E.

    2003-07-01

    Mounting evidence suggests that CI Carbonaceaous Chondrites belong in the Mars meteorite family. They thus represent samples, like ALH84001, of the Noachian surface environment, and are rich in organic matter, suggesting a living environment.

  7. 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.

  8. Radiative origin of all quark and lepton masses through dark matter with flavor symmetry.

    PubMed

    Ma, Ernest

    2014-03-01

    The fundamental issue of the origin of mass for all quarks and leptons (including Majorana neutrinos) is linked to dark matter, odd under an exactly conserved Z2 symmetry which may or may not be derivable from an U(1)D gauge symmetry. The observable sector interacts with a proposed dark sector which consists of heavy neutral singlet Dirac fermions and suitably chosen new scalars. Flavor symmetry is implemented in a renormalizable context with just the one Higgs doublet (ϕ(+), ϕ(0)) of the standard model in such a way that all observed fermions obtain their masses radiatively through dark matter. PMID:24655241

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. The spatial distribution of dark matter annihilation originating from a gamma-ray line signal

    NASA Astrophysics Data System (ADS)

    Lu, Tong-Suo; Dong, Tie-Kuang; Wu, Jian

    2014-05-01

    The GeV-TeV γ-ray line signal is the smoking gun signature of dark matter annihilation or decay. The detection of such a signal is one of the main targets of some space-based telescopes, including Fermi-LAT and the upcoming missions CALET, DAMPE and Gamma-400. An important feature of γ-ray line photons that originate from dark-matter-annihilation is that they are concentrated at the center of the Galaxy. So far, no reliable γ-ray line has been detected by Fermi-LAT, and the upper limits on the cross section of annihilation into γ-rays have been reported. We use these upper limits to estimate the “maximal” number of γ-ray line photons detectable for Fermi-LAT, DAMPE and Gamma-400, and then investigate the spatial distribution of these photons. We show that the center of the distribution will usually be offset from the Galactic center (Sgr A*) due to the limited statistics. Such a result is almost independent of models of the dark matter distribution, and will render the reconstruction of the dark matter distribution with the γ-ray line signal very challenging for foreseeable space-based detectors.

  2. 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.

  3. Highly Siderophile Elements in Shocked and Unshocked Chondrites

    NASA Technical Reports Server (NTRS)

    Horan, M. F.; Walker, R. J.; Rubin, A. E.

    2001-01-01

    High precision abundances of Re, Os, Pt, Ir, Ru, and Pd are combined with Re-Os isotopic data to demonstrate that HSE provide a distinctive fingerprint for each of the chondrite groups. Additional information is contained in the original extended abstract.

  4. 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.

  5. 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?

  6. Thermal history of chondrites - Hot accretion vs. metamorphic reheating

    NASA Technical Reports Server (NTRS)

    Haack, Henning; Taylor, G. J.; Scott, E. R. D.; Keil, Klaus

    1992-01-01

    The thermal evolution of chondrules is investigated for the stages including primary heating through accretion to parent-body processing to determine whether the chondrules could be hot during accretion. Theoretical attention is given to whether chondrites of different petrologic types could have originated by means of hot accretion or metamorphic reheating. Data are presented from cooling-rate experiments and from calculations of heat retention required for the hot-accretion scenario. The accretion of chondrules hotter than 800 C is shown to be inconsistent with constraints on chondrule thermal evolution, in particular the slow cooling environment of chondrules vs the apparent cooling of chondrites in cold environments. It is argued that petrologic chondrites are formed by cold accretion and subsequently by metamorphic heating.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. CALET investigation of the origin of cosmic-ray electrons and search for dark matter

    NASA Astrophysics Data System (ADS)

    Yoshida, Kenji; Torii, Shoji; Kasahara, Katsuaki; Akaike, Yosui; Tamura, Tadahisa; Mori, Masaki; Ioka, Kunihito; Kawanaka, Norita

    The CALorimetric Electron Telescope, CALET, is a new all-sky gamma-ray and electron obser-vatory being developed for the Exposure Facility of Japanese Experiment Module (JEM-EF) on the International Space Station (ISS). The main instrument consists of an imaging calorimeter of scintillating fibers, IMC, a total absorption calorimeter of BGO, TASC, and silicon pixel ar-ray, SIA. CALET has a unique capability to observe high-energy electrons in 1GeV -10TeV and gamma rays in 10GeV -several TeV with an energy resolution better than a few percent above 100 GeV, an angular resolution of 0.1deg above 100GeV, and a hadron rejection power larger than 105 . The high precise measurements of electron energy spectrum and arrival directions enable us to detect distinctive features from nearby cosmic-ray electron sources and WIMP dark matter. Excellent energy resolution of CALET, which is much better than Fermi-LAT or air Cherenkov telescopes, is also ideal to detect gamma-ray lines in the GeV-TeV region from WIMP dark matter. In this paper, we present scientific prospects of CALET for investigation of the origin of cosmic-ray electrons and dark matter search.

  13. 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

  14. 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

    2014-06-01

    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. PMID:24804819

  15. 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

  16. Light in Condensed Matter in the Upper Atmosphere as the Origin of Homochirality: Circularly Polarized Light from Rydberg Matter

    NASA Astrophysics Data System (ADS)

    Holmlid, Leif

    2009-08-01

    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.

  17. 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. PMID:19586392

  18. 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

  19. CV and CM chondrite impact melts

    NASA Astrophysics Data System (ADS)

    Lunning, Nicole G.; Corrigan, Catherine M.; McSween, Harry Y.; Tenner, Travis J.; Kita, Noriko T.; Bodnar, Robert J.

    2016-09-01

    Volatile-rich and typically oxidized carbonaceous chondrites, such as CV and CM chondrites, potentially respond to impacts differently than do other chondritic materials. Understanding impact melting of carbonaceous chondrites has been hampered by the dearth of recognized impact melt samples. In this study we identify five carbonaceous chondrite impact melt clasts in three host meteorites: a CV3red chondrite, a CV3oxA chondrite, and a regolithic howardite. The impact melt clasts in these meteorites respectively formed from CV3red chondrite, CV3oxA chondrite, and CM chondrite protoliths. We identified these impact melt clasts and interpreted their precursors based on their texture, mineral chemistry, silicate bulk elemental composition, and in the case of the CM chondrite impact melt clast, in situ measurement of oxygen three-isotope signatures in olivine. These impact melts typically contain euhedral-subhedral olivine microphenocrysts, sometimes with relict cores, in glassy groundmasses. Based on petrography and Raman spectroscopy, four of the impact melt clasts exhibit evidence for volatile loss: these melt clasts either contain vesicles or are depleted in H2O relative to their precursors. Volatile loss (i.e., H2O) may have reduced the redox state of the CM chondrite impact melt clast. The clasts that formed from the more oxidized precursors (CV3oxA and CM chondrites) exhibit phase and bulk silicate elemental compositions consistent with higher intrinsic oxygen fugacities relative to the clast that formed from a more reduced precursor (CV3red chondrite). The mineral chemistries and assemblages of the CV and CM chondrite impact melt clasts identified here provide a template for recognizing carbonaceous chondrite impact melts on the surfaces of asteroids.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Origin of B0 orientation dependent R2(*) (=1/T2(*)) in white matter.

    PubMed

    Oh, Se-Hong; Kim, Young-Bo; Cho, Zang-Hee; Lee, Jongho

    2013-06-01

    Recent MRI studies have demonstrated that the relative orientation of white matter fibers to the B0 field significantly affects R2(*) measurement. In this work, the origin of this effect was investigated by measuring R2 and R2(*) in multiple orientations and fitting the results to magnetic susceptibility-based models and magic angle-based models. To further explore the source of magnetic susceptibility effect, the contribution of tissue iron to the orientation dependent R2(*) contrast was investigated. Additionally, the effects of temperature on R2(*) and orientation dependent R2(*) contrasts were studied to understand the differences reported between a fixed specimen at room temperature and in vivo at body temperature. The results suggest that the B0 dependent R2(*) variation is better explained by the magnetic susceptibility-based model with susceptibility anisotropy. However, extracting tissue iron did not reduce the orientation dependent R2(*) contrast, suggesting iron is not the origin of the contrast. This leaves susceptibility effects from myelin as the most probable origin of the contrast. Temperature showed large contribution on both R2(*) and orientation dependent R2(*) contrasts, explaining a portion of the contrast difference between the in-vivo and in-vitro conditions. PMID:23376494

  6. 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.

  7. 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

  8. Distribution, origin and transformation of amino sugars and bacterial contribution to estuarine particulate organic matter

    NASA Astrophysics Data System (ADS)

    Khodse, Vishwas B.; Bhosle, Narayan B.

    2013-10-01

    Amino sugars including bacterial biomarker muramic acid (Mur) were investigated in suspended particulate matter (SPM) to understand their distribution, origin, and biogeochemical cycling and the contribution of bacteria to particulate organic matter (POM) of the Mandovi estuary. SPM was collected from 9 sampling stations in the Mandovi estuary during the pre-monsoon (March) and monsoon (August). Total particulate amino sugar (TPAS) concentrations and yields varied spatially and were 2 to 5 times higher during the monsoon than the pre-monsoon. Negative correlation between salinity and TPAS-C yields [TPAS-C/particulate organic carbon (POC)×100] indicates the influence of terrestrial organic matter on the transport of TPAS-carbon. Glucosamine (GlcN), galactosamine (GalN), and mannosamine (ManN) were abundant during the monsoon. Low GlcN/GalN ratios (<3) indicate bacteria as the major source of amino sugars. Higher amino sugar yields and lower GlcN/GalN ratios during the monsoon than the pre-monsoon indicate enhanced transformation and greater bacterial contribution to POM during the former season. Degradation trends observed with TPAS were well supported by those obtained with carbohydrates and amino acids. Based on Mur concentrations, bacteria accounted for 24% to 35% of the POC and 24% to 62% of the total particulate nitrogen (TPN). Intact bacterial cells, however accounted for a small proportion of POC (2.5% to 4%) and TPN (9% to 11%). Our study suggests that POM was subjected to extensive diagenetic transformation, and its composition was influenced by bacteria, especially during the monsoon.

  9. 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.

  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. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. Abundance, major element composition and size of components and matrix in CV, CO and Acfer 094 chondrites

    NASA Astrophysics Data System (ADS)

    Ebel, Denton S.; Brunner, Chelsea; Konrad, Kevin; Leftwich, Kristin; Erb, Isabelle; Lu, Muzhou; Rodriguez, Hugo; Crapster-Pregont, Ellen J.; Friedrich, Jon M.; Weisberg, Michael K.

    2016-01-01

    The relative abundances and chemical compositions of the macroscopic components or "inclusions" (chondrules and refractory inclusions) and fine-grained mineral matrix in chondritic meteorites provide constraints on astrophysical theories of inclusion formation and chondrite accretion. We present new techniques for analysis of low count/pixel Si, Mg, Ca, Al, Ti and Fe X-ray intensity maps of rock sections, and apply them to large areas of CO and CV chondrites, and the ungrouped Acfer 094 chondrite. For many thousands of manually segmented and type-identified inclusions, we are able to assess, pixel-by-pixel, the major element content of each inclusion. We quantify the total fraction of refractory elements accounted for by various types of inclusion and matrix. Among CO chondrites, both matrix and inclusion Mg/Si ratios approach the solar (and bulk CO) ratio with increasing petrologic grade, but Si remains enriched in inclusions relative to matrix. The oxidized CV chondrites with higher matrix/inclusion ratios exhibit more severe aqueous alteration (oxidation), and their excess matrix accounts for their higher porosity relative to reduced CV chondrites. Porosity could accommodate an original ice component of matrix as the direct cause of local alteration of oxidized CV chondrites. We confirm that major element abundances among inclusions differ greatly, across a wide range of CO and CV chondrites. These abundances in all cases add up to near-chondritic (solar) bulk abundance ratios in these chondrites, despite wide variations in matrix/inclusion ratios and inclusion sizes: chondrite components are complementary. This complementarity provides a robust meteoritic constraint for astrophysical disk models.

  17. 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.

  18. 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.

  19. 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.; Mikouchi, T.

    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.

  20. 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.

  1. 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.

  2. 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.

  3. Manganese chromium isotope systematics of carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Shukolyukov, A.; Lugmair, G. W.

    2006-10-01

    Cr preferentially resides in the chondrules. Thus, the Mn/Cr ratio also follows the sequence CI > CM > CO > CV and is correlated with 54Cr. The acid-resistant residues of carbonaceous chondrites are characterized by relatively large excesses of 54Cr and moderate deficits of 53Cr. The magnitude of these excesses and deficits decreases in the sequence CI, CM, CV and may imply that Cr in the CM, and CV residues is increasingly more equilibrated with Cr from the rest of the meteorites. The 53Cr/ 52Cr and 54Cr/ 52Cr ratios in the residues are anti-correlated indicating that there are at least two Cr components of possibly presolar origin. All residues have large excesses of the most neutron-rich Ti isotope, 50Ti *. The pattern of 50Ti * does not exactly follow that observed for 54Cr * but it is generally similar. The Cr isotope systematic of the pallasite Eagle Station indicates that the precursor of this meteorite was a CV-type material. The 53Mn- 53Cr system indicates that the Cr isotopes equilibrated in this meteorite 4557.5 ± 0.6 Ma ago.

  4. Visualizing, dating and determining the origin of the primitive carbonaceous matter in rocks: the potential of electron paramagnetic resonance

    NASA Astrophysics Data System (ADS)

    Binet, Laurent; Gourier, Didier; Delpoux, Olivier; Skrzypczak-Bonduelle, Audrey; Vezin, Herve; Derenne, Sylvie; Robert, Francois

    The study of primitive life on Earth is an essential task to determine the physical and chemical processes, which can lead to the emergence of life, and to devise methods to detect possible traces of life on Mars. Traces of primitive life should occur as residual fossil carbonaceous matter embedded in ancient rocks. However, on the early Earth or the early Mars, several sources, namely biological, chemical or extraplanetary, of carbonaceous matter must be considered. Besides, any fossilized carbonaceous matter, whether biological or abiotic, undergoes a complex evolution over geological times so that the memory of its precursors may be partially lost. Therefore the origin of ancient carbonaceous matter is difficult to assess on a chemical or structural basis. In addition, in the case of terrestrial rocks, unavoidable biogenic contamination by endolithic bacteria complicates the problem of proving the origin of primitive terrestrial organic matter. In the specific case of possible Martian rocks, it appears compelling to use techniques able to perform a non-destructive detection and analysis of the possible carbonaceous matter in such precious samples. Fossil carbonaceous matters contain radicals corresponding to unpaired electrons associated with broken chemical bonds or structural defects. These organic radicals are magnetic species, which can be detected and analyzed by Electron Paramagnetic Resonance (EPR). This technique is non-destructive, and sensitive enough to detect ideally 1 ppm of carbonaceous matter in a rock. To assess the potential of radicals to trace back the history and the origin of ancient carbonaceous matter, we performed an EPR study of a series of siliceous rocks (cherts) containing fossil carbonaceous matter with ages ranging from 45 Myr to 3.46 Byr. We showed that the distribution of the carbonaceous matter can be visualized within bulk sample by EPR imaging, with a submillimeter resolution, which may help detecting possible fossil bacterial

  5. 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.

  6. 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.

  7. Metal phases in ordinary chondrites: Magnetic hysteresis properties and implications for thermal history

    NASA Astrophysics Data System (ADS)

    Gattacceca, J.; Suavet, C.; Rochette, P.; Weiss, B. P.; Winklhofer, M.; Uehara, M.; Friedrich, Jon M.

    2014-04-01

    Magnetic properties are sensitive proxies to characterize FeNi metal phases in meteorites. We present a data set of magnetic hysteresis properties of 91 ordinary chondrite falls. We show that hysteresis properties are distinctive of individual meteorites while homogeneous among meteorite subsamples. Except for the most primitive chondrites, these properties can be explained by a mixture of multidomain kamacite that dominates the induced magnetism and tetrataenite (both in the cloudy zone as single-domain grains, and as larger multidomain grains in plessite and in the rim of zoned taenite) dominates the remanent magnetism, in agreement with previous microscopic magnetic observations. The bulk metal contents derived from magnetic measurements are in agreement with those estimated previously from chemical analyses. We evidence a decreasing metal content with increasing petrologic type in ordinary chondrites, compatible with oxidation of metal during thermal metamorphism. Types 5 and 6 ordinary chondrites have higher tetrataenite content than type 4 chondrites. This is compatible with lower cooling rates in the 650-450 °C interval for higher petrographic types (consistent with an onion-shell model), but is more likely the result of the oxidation of ordinary chondrites with increasing metamorphism. In equilibrated chondrites, shock-related transient heating events above approximately 500 °C result in the disordering of tetrataenite and associated drastic change in magnetic properties. As a good indicator of the amount of tetrataenite, hysteresis properties are a very sensitive proxy of the thermal history of ordinary chondrites, revealing low cooling rates during thermal metamorphism and high cooling rates (e.g., following shock reheating or excavation after thermal metamorphism). Our data strengthen the view that the poor magnetic recording properties of multidomain kamacite and the secondary origin of tetrataenite make equilibrated ordinary chondrites challenging

  8. 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.

  9. Chemical and petrographic correlations among carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Van Schmus, W. R.; Hayes, J. M.

    1974-01-01

    Detailed study of the petrographic and chemical properties of carbonaceous chondrites shows that the four distinct petrographic subtypes may be related to one of two distinct chemical subdivisions. These subdivisions are recognized primarily by the relative abundances of the nonvolatile elements Si, Ca, Al, Ti, Cu and Fe. C1, C2 and C3(O) chondrites form one subdivision. Vigarano subtype chondrites form the other subdivision and include chondrites previously referred to as C2, C3 and C4. Normalized to silicon, the abundances of Ca, Al and Ti are relatively enriched in Vigarano subtype chondrites, whereas Fe and Cu are relatively more abundant in C1, C2 and C3(O) chondrites. Volatile elements tend to correlate with petrographic subtypes rather than with chemical subdivisions.

  10. Multiple and Fast: The Accretion of Ordinary Chondrite Parent Bodies

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    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 ~105 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.

  11. 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.

  12. 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.

  13. 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

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

    PubMed

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

    2015-07-01

    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

  15. 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.

  16. 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.

  17. 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.

  18. Titanium oxide Magneli phases in four chondritic porous interplanetary dust particles

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    Detailed analytical electron microscope analyses of four fine-grained chondritic porous interplanetary dust particles (IDPs) reveal the presence of titanium oxide Magneli phases, Ti(n)O(2n-1) (n = 4, 5, 6), and rare Ti-metal. The association of Magneli phases, Ti-metal, and carbonaceous material in chondritic IDPs, along with the grain size distributions of Ti-metal and Magneli phases and equilibrium dissociation pressures for these oxygen-deficient Ti-oxides, support in situ solid carbon gasification in these extraterrestrial particles. The active catalyst in this process is titanium metal that may be of interstellar origin. A model is proposed that explains the higher solid carbon content of chondritic IDPs relative to bulk carbon abundances typical for carbonaceous chondrite matrices that represent another type of more metamorphosed undifferentiated solar system bodies.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

    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 SiO 2 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) Δ E≈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 SiO 2 matrix, and is not due to a latter contamination by bacteria, as was recently found in meteoritic samples.

  1. 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. PMID:15134734

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. An ordinary chondrite impactor for the Popigai crater, Siberia

    NASA Astrophysics Data System (ADS)

    Tagle, Roald; Claeys, Philippe

    2005-06-01

    With a diameter of ˜100 km, Popigai in Northern Siberia is the largest crater known in the Cenozoic. The concentrations in platinum group elements (PGE) were analyzed in twenty samples of homogeneous impact melt collected in the northwestern flank of the crater to identify the composition of the projectile. The method selected was preconcentration by NiS fire assay followed by inductively coupled plasma-mass spectrometry (ICP-MS). This technique measures all the PGE (except Os) and by using aliquots >10g, the results are highly reproducible. The major and trace element composition of the impact melt resembles that of gneissic lithologies of the Anabar shield, which are representative of the target rock. The PGE are enriched in the melt by factors of 3 to 14 compared to the main target lithology, but the meteoritic contamination is only around 0.2 wt.%. Using plots of elemental ratios such as Ru/Rh vs. Pt/Pd or Ru/Rh vs. Pd/Ir, the Popigai impactor is clearly identified as an ordinary chondrite and most likely L-chondrite. This study indicates that PGE elemental ratios allow discrimination of the type of impactor, even in the case of low meteoritic contamination. This study confirms that a significant fraction of the crater-forming projectiles presently documented could have an ordinary chondrite composition. Their probable source, the S-type asteroids, appears to form the majority of the bodies in the main asteroid belt and among Near Earth Objects (NEOs). The ordinary chondrite origin of the Popigai projectile supports an asteroidal origin for the late Eocene impacts as a plausible alternative to the comet shower scenario proposed by Farley et al. (1998).

  9. 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).

  10. (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).

  11. Chondritic xenon in the Earth's mantle.

    PubMed

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

    2016-05-01

    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. PMID:27111512

  12. The origin of rotation, dense matter physics and all that: a tribute to Pavle Savić.

    NASA Astrophysics Data System (ADS)

    Čelebonović, V.

    1995-04-01

    This is a review of the main physical ideas and examples of applicability in astrophysics and pure physics of a semiclassical theory of dense matter proposed by Pavle Savićand Radivoje Kašanin in the early sixties. A hypothesis, advanced by Savić with the aim of solving the problem of the origin of rotation of celestial bodies, will also be discussed. The paper is dedicated to the memory of Pavle Savić.

  13. 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

  14. Origins.

    ERIC Educational Resources Information Center

    Online-Offline, 1999

    1999-01-01

    Provides an annotated list of resources dealing with the theme of origins of life, the universe, and traditions. Includes Web sites, videos, books, audio materials, and magazines with appropriate grade levels and/or subject disciplines indicated; professional resources; and learning activities. (LRW)

  15. 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.

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

    NASA Astrophysics Data System (ADS)

    Righter, K.; Cosca, M. A.; Morgan, L. E.

    2016-09-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Righter, K.; Cosca, M. A.; Morgan, L. E.

    2016-07-01

    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.

  18. Porosity and Permeability of Chondritic Materials

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael E.; Corrigan, Catherine M.; Dahl, Jason; Long, Michael

    1996-01-01

    We have investigated the porosity of a large number of chondritic interplanetary dust particles and meteorites by three techniques: standard liquid/gas flow techniques, a new, non-invasive ultrasonic technique, and image processing of backscattered images . The latter technique is obviously best suited to sub-kg sized samples. We have also measured the gas and liquid permeabilities of some chondrites by two techniques: standard liquid/gas flow techniques, and a new, non-destructive pressure release technique. We find that chondritic IDP's have a somewhat bimodal porosity distribution. Peaks are present at 0 and 4% porosity; a tail then extends to 53%. These values suggest IDP bulk densities of 1.1 to 3.3 g/cc. Type 1-3 chondrite matrix porosities range up to 30%, with a peak at 2%. The bulk porosities for type 1-3 chondrites have the same approximate range as exhibited by matrix, indicating that other components of the bulk meteorites (including chondrules and aggregates) have the same average porosity as matrix. These results reveal that the porosity of primitive materials at scales ranging from nanogram to kilogram are similar, implying similar accretion dynamics operated through 12 orders of size magnitude. Permeabilities of the investigated chondrites vary by several orders of magnitude, and there appears to be no simple dependence of permeability with degree of aqueous alteration, or chondrite type.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. 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

  10. I-Xe systematics in LL chondrites

    NASA Technical Reports Server (NTRS)

    Bernatowicz, T. J.; Podosek, F. A.; Swindle, T. D.; Honda, M.

    1988-01-01

    A stepwise heating analysis of Ar and Xe data from five neutron-irradiated whole rock LL chondrites (Soko Banja, Alta Ameen, Tuxtuac, Guidder, and Olivenza) is presented, emphasizing the complicated thermal history of ordinary chondrites. None of the present meteorites show a well-defined (Ar-40)-(Ar-39) apparent age plateau comprised of more than two release fractions. Most of the samples are found to yield well-defined high-temperature correlations between Xe-129/Xe-130 and Xe-128/Xe-130, and thus determinations of I-129/I-127 and Xe-129/Xe-130 at the time of isotopic closure for Xe. As in the case of other ordinary chondrites, the I-Xe systematics for LL chondrites correlate neither with a metamorphic grade nor with chronologies based opon other methods.

  11. Tin in a chondritic interplanetary dust particle

    NASA Astrophysics Data System (ADS)

    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 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.

  12. Alkali differentiation in LL-chondrites

    NASA Astrophysics Data System (ADS)

    Wlotzka, F.; Palme, H.; Spettel, B.; Wanke, H.; Fredriksson, K.; Noonan, A. F.

    1983-04-01

    The Kraehenberg and Bhola LL-group chondrites are heterogeneous agglomerates which contain a variety of lithic fragments and chondrules as well as crystal fragments. Both meteorites contain large, cm-sized fragments with high K enrichments. The K-rich inclusions are fragments of larger rock bodies which crystallized from melts of chondritic parent material that had previously been enriched in K and in heavier alkalies,while also being depleted in Na and metal. It is suggested that the K enrichment occurred as an exchange for Na in feldspars via a vapor phase, whose presence on the chondrite parent body (or bodies) is supported by the recent finding of fluid inclusions in chondritic silicates. Cooling rate considerations indicate that the K-rich rock units could not have been very large, implying that the K-rich materials were locally molten by, for example, impact.

  13. Impact melt products of chondritic material

    NASA Technical Reports Server (NTRS)

    Rubin, A. E.

    1985-01-01

    Experimental data concerning impact melting processes in chondritic material are reviewed. It is shown that a large variety of objects in chondritic meteorites could have formed as a result of impact melting, including: shock veins; metal-troilite mixtures; metal and sulfide nodules; melt pockets and vugs. The type of object produced in an impact melt is related to the interaction of the shock waves with the particular target rock. It is suggested that various iron meteorites (including groups IAB, IIICD, and IIE, as well as several ungrouped irons) were formed from individual melt pools in chondritic regoliths. The small-scale structure of impact-melted metallic Fe,Ni and troilite in Weston (H chondrite regolith breccia) is illustrated in a photograph.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. Classification of eight ordinary chondrites from Texas

    NASA Astrophysics Data System (ADS)

    Ehlmann, A. J.; Keil, K.

    1985-06-01

    Based on optical microscopy and electron microprobe analyses, eight previously undescribed or poorly known chondrites were classified into compositional groups, petrologic types, and degree of shock alteration. These chondrites are: Leander, L4b; Nazareth(a), L6d; La Villa, H4b; Mereta, H4c; Gail, H4d; Shafter Lake, H5a; Uvalde, H5d; and Howe, H5d.

  19. Chondritic Earth: comparisons, guidelines and status

    NASA Astrophysics Data System (ADS)

    McDonough, W. F.

    2014-12-01

    The chemical and isotopic composition of the Earth is rationally understood within the context of the chondritic reference frame, without recourse to hidden reservoirs, collision erosion, or strict interpretation of an enstatite chondrite model. Challenges to interpreting the array of recent and disparate chemical and isotopic observations from meteorites need to be understood as rich data harvests that inform us of the compositional heterogeneity in the early solar system. Our ability to resolve small, significant compositional differences between chondrite families provide critical insights into integrated compositional signatures at differing annuli distances from the Sun (i.e., 1-6 AU). Rigorous evaluation of chondritic models for planets requires treatment of both statistical and systematic uncertainties - to date these efforts are uncommonly practiced. Planetary olivine to pyroxene ratio reflects fO2 and temperature potentials in the nebular, given possible ISM compositional conditions; thus this ratio is a non-unique parameter of terrestrial bodies. Consequently the Mg/Si value of a planet (ie., olivine to pyroxene ratio) is a free variable; there is no singular chondritic Mg/Si value. For the Earth, there is an absence of physical and chemical evidence requiring a major element, chemical distinction between the upper and lower mantle, within uncertainties. Early Earth differentiation likely occurred, but there is an absence of chemical and isotopic evidence of its imprint. Chondrites, peridotites, komatiites, and basalts (ancient and modern) reveal a coherent picture of a chondritic compositional Earth, with compositionally affinities to enstatite chondrites. At present results from geoneutrino studies non-uniquely support these conclusions. Future experiments can provide true transformative insights into the Earth's thermal budget, define compositional BSE models, and will restrict discussions on Earth dynamics and its thermal evolution.

  20. Implications of poikilitic textures in LL-group chondrites

    NASA Technical Reports Server (NTRS)

    Fodor, R. V.; Keil, K.

    1975-01-01

    Five lithic fragments with poikilitic textures in five LL-group chondrites are examined by microscope and electron microprobe to determine whether the textures have resulted from processes related to impact events, such as thermal metamorphism or partial melting. The bulk and pyroxene compositions of the fragments are determined. The compositional characteristics of minerals in certain fragments are found to indicate an apparent melt origin. It is concluded that impact processes produced the poikilitic textures and that complete melting, partial melting, and solid-state recrystallization all have had some part in producing the textures.

  1. 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.

  2. 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

  3. Compositional and petrographic similarities of CV and CK chondrites: A single group with variations in textures and volatile concentrations attributable to impact heating, crushing and oxidation

    NASA Astrophysics Data System (ADS)

    Wasson, John T.; Isa, Junko; Rubin, Alan E.

    2013-05-01

    Greenwood et al. (2010) gathered data on O-isotopic and elemental compositions and reevaluated literature data for CV and CK chondrites. They concluded that these two chondrite groups originated on the same parent asteroid, with CK chondrites being metamorphosed CV chondrites (which are otherwise missing types 4 through 6). To test this interpretation we have gathered new instrumental neutron-activation-analysis (INAA) data for CV and CK chondrites and reexamined their petrographic features. The new INAA data like the older data show scatter attributable to weathering effects, but we conclude that the refractory lithophile abundances are the same in CV and CK, in agreement with the Greenwood et al. interpretation. Several volatile elements are significantly lower in CK than in CV chondrites. Among the elements we determine, the greatest difference between CV and CK is found for Br, for which the CV/CK ratio is ∼4; As and Sb are about 20% lower in CK than CV and smaller differences are observed for Zn, Ga and Se. It seems likely that volatiles were lost during impact-heating events that also provided the heat responsible for metamorphic recrystallization. Within statistical uncertainty, chondrules in CV and CK chondrites are the same size and have similar textural distributions. A significant petrographic difference between CK and CV chondrites cited by Kallemeyn et al. (1991) was the much higher percentage of igneous rims around CV chondrules. However, we now recognize that many chondrules in CK3.8 NWA 1559 have igneous rims and in CK4 chondrites, igneous rims are recognizable by their associated sulfide-rich rings; there are no quantifiable CV-CK differences in igneous-rim abundances. We used Ca and Al maps to show that CK chondrites have CAI abundances similar to those of CV chondrites. It thus appears that there are no resolvable pre-metamorphic petrographic differences between CV and CK chondrites. We recommend that the “CK” designation be abandoned and

  4. Origins of R2* orientation dependence in gray and white matter.

    PubMed

    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 (R2*) can be used to quantify important properties of biological tissue. Surprisingly, the mechanism of R2* dependence on tissue orientation is not well understood. The primary goal of this paper was to characterize orientation dependence of R2* 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 R2' (reversible contribution to the transverse relaxation rate from local field inhomogeneities) in a voxel given measurements of the local Larmor frequency shift. R2' 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 R2* orientation dependence using image-registered optical density measurements from histochemical staining. Our results demonstrate that the R2* 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, R2* and fL have no orientation dependence but retain a linear dependence on tissue iron concentration and hence Δχ. PMID:24374633

  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. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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. PMID:25288758

  12. 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.

  13. Refractory precursor components of Semarkona chondrules and the fractionation of refractory elements among chondrites

    NASA Astrophysics Data System (ADS)

    Grossman, J. N.; Wasson, J. T.

    1983-04-01

    Instrumental neutron activation analysis has been used to measure about 20 of the lithophile elements in 30 chondrules from the Semarkona chondrite. The amounts of oxidized iron were calculated from other compositional parameters, and Si concentrations are estimated from mass-balance considerations. It is suggested that the refractory component probably forms from fine grained materials that were able to equilibrate down to lower nebular temperatures. The chondrite matrix may have had an origin similar to that of the nonrefractory material. The low abundance of refractories and Mg in ordinary and enstatite chondrites was produced by the loss of materials having a higher refractory element/Mg ratio than that of the refractory element of the chondrules.

  14. 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.

  15. Siderophile element constraints on the formation of metal in the metal-rich chondrites Bencubbin, Weatherford, and Gujba

    NASA Astrophysics Data System (ADS)

    Campbell, Andrew J.; Humayun, Munir; Weisberg, Michael K.

    2002-02-01

    Laser ablation inductively coupled plasma mass spectrometry was used to measure abundances of P, Cr, Fe, Co, Ni, Cu, Ga, Ge, As, Mo, Ru, Rh, Pd, Sn, Sb, W, Re, Os, Ir, Pt, and Au in metal grains in the Bencubbin-like chondrites Bencubbin, Weatherford, and Gujba to determine the origin of large metal aggregates in bencubbinites. A strong volatility-controlled signature is observed among the metal grains. The refractory siderophiles Ru, Rh, Re, Os, Ir, and Pt are unfractionated from one another, and are present in approximately chondritic relative abundances. The less refractory elements Fe, Co, Ni, Pd, and Au are fractionated from the refractory siderophiles, with a chondritic Ni/Co ratio and a higher than chondritic Pd/Fe ratio. The moderately volatile siderophile elements Ga, Ge, As, Sn, and Sb are depleted in the metal, relative to chondritic abundances, by up to 3 orders of magnitude. The trace siderophile element data are inconsistent with the following proposed origins of Bencubbin-Weatherford-Gujba metal: (1) condensation from the canonical solar nebula, (2) oxidation of an initially chondritic metal composition, and (3) equilibration with a S-rich partial melt. A condensation model for metal-enriched (×10 7 CI) gas is developed. Formation by condensation or evaporation in such a high-density, metal-enriched gas is consistent with the trace element measurements. The proposed model for generating such a gas is protoplanetary impact involving a metal-rich body.

  16. 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

  17. Organic Matter and the Origin of Life in the Solar System

    NASA Astrophysics Data System (ADS)

    Oró, John

    The biogenic elements (H, C, N, O, S, P) and organic matter are some of the major constituents of the universe. Indeed, more than three fourths of the individual chemical species identified in the interstellar medium are simple compounds of carbon and/or of biogenic elements (e.g., NH_3, H_2, HCN, HCHO, HC_3, etc). When the protosolar nebula condensed to form the Solar System, organic compounds became part of the outer planetary bodies, such as Jupiter, Saturn, and Titan as well as comets and dark asteroids. On the other hand, because of their proximity to the Sun, the terrestrial planets become significantly depleted of water and other volatile compounds. The acquisition of water and organic compounds presumably took place in good measure by late accretion from comets and other planetesimals. Upon capture of comets by the Earth, the synthesis of biochemical compounds such as amino acids, purines and pyrimidines could take place from simple cometary molecules. This, together with the fact that the Earth's orbit lies within a circumstellar habitable zone is conidered to have made possible the emergence of life on our planet some four billion years ago. This review briefly discusses relevant aspects of: (1) The organic matter in the interstellar medium. (2) The formation of the Earth- Moon system and the role of comets and other planetesimals in contributing organic matter to the primitive Earth. (3) The prebiotic synthesis of biochemical compounds and the emergence of life on our planet. (4) The possible existence of life on Mars, Europa and other bodies of the Solar System, and (5) The discoveries of protoplanetary disks around other stars, which suggest that the processes which occurred in our system are probably occuring now in extrasolar protoplanetary systems.

  18. Possible dark matter origin of the gamma ray emission from the Galactic Center observed by HESS

    NASA Astrophysics Data System (ADS)

    Cembranos, J. A. R.; Gammaldi, V.; Maroto, A. L.

    2012-11-01

    We show that the gamma ray spectrum observed with the HESS array of Cherenkov telescopes coming from the Galactic Center region and identified with the source HESS J1745-290 is well fitted by the secondary photons coming from dark matter (DM) annihilation over a diffuse power law background. The amount of photons and morphology of the signal localized within a region of few parsecs, require compressed DM profiles as those resulting from baryonic contraction, which offer ˜103 enhancements in the signal over DM alone simulations. The fitted background from HESS data is consistent with recent Fermi-LAT observations of the same region.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. A hydrogen isotope study of CO3 type carbonaceous chondrites; comparison with type 3 ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Morse, A. D.; Newton, J.; Pillinger, C. T.

    1993-01-01

    Meteorites of the Ornans type 3 carbonaceous chondrites exhibit a range in degree of equilibration, attributed to differing amounts of thermal metamorphism. These differences have been used to split the CO3 chondrites into petrologic sub-types from 3.0, least equilibrated, to 3.7, being most equilibrated. This is similar to the system of assigning the type 3 ordinary chondrites into petrologic sub-types 3.0 to 3.9 based upon thermoluminescence (TL) and other properties; however, the actual range of thermal metamorphism experienced by CO3 chondrites is much less than that of the type 3 ordinary chondrites. The least equilibrated ordinary chondrites show evidence of aqueous alteration and have high D/H ratios possibly due to a deuterium-rich organic carrier. The aim of this study was to determine whether the CO3 chondrites, which have experienced similar secondary conditions to the type 3 ordinary chondrites, also contain a similar deuterium-rich carrier. To date a total of 5 CO3 meteorites, out of a set of 11 for which carbon and nitrogen isotopic data are available, have been analyzed. Ornans has not been analyzed yet, because it does not appear to fit in with the metamorphic sequence exhibited by the other CO3 chondrites; it also has an extremely high delta-D value of +2150 percent, unusual for such a comparatively equilibrated meteorite (type 3.4). Initial results indicate that the more equilibrated CO3's tend to have lower delta-D values, analogous to the higher petrologic type ordinary chondrites. However this is complicated by the effects of terrestrial weathering and the small data-set.

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. Origin and fate of particulate and dissolved organic matter in a naturally iron-fertilized region of the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Tremblay, L.; Caparros, J.; Leblanc, K.; Obernosterer, I.

    2014-10-01

    Natural iron fertilization of high-nutrient low-chlorophyll (HNLC) waters induces annually occurring spring phytoplankton blooms off Kerguelen Islands (Southern Ocean). To examine the origin and fate of particulate and dissolved organic matter (POM and DOM), D- and L-amino acids (AA) were quantified at bloom and HNLC stations. Total hydrolysable AA accounted for 21-25% of surface particulate organic carbon (%POCAA) at the bloom sites, but for 10% at the HNLC site. A marked decrease in %POCAA with depth was observed at the most productive stations leading to values between 3 and 5% below 300 m depth. AA contributed to only 0.9-4.4% of dissolved organic carbon (%DOCAA) at all stations. The only consistent vertical trend was observed at the most productive station (A3-2) where %DOCAA decreased from ∼2% in the surface waters to 0.9% near 300 m. These AA yields and other markers revealed that POM and DOM were more rapidly altered or mineralized at the bloom sites compared to the HNLC site. Different molecular markers indicated that POM mostly originated from diatoms and bacteria. The estimated average proportion of POM from intact phytoplankton cells in surface waters was 45% at the bloom station A3-2, but 14% at the HNLC site. Estimates based on D-AA yields indicated that ∼15% of POM and ∼30% of DOM was of bacterial origin (cells and cell fragments) at all stations. Surprisingly, the DOM in HNLC waters appeared less altered than the DOM from the bloom, had slightly higher dissolved AA concentrations, and showed no sign of alteration within the water column. Unfavorable conditions for bacterial degradation in HNLC regions can explain these findings. In contrast, large inputs of labile organic molecules and iron, likely stimulate the degradation of organic matter (priming effect) and the production of more recalcitrant DOM (microbial carbon pump) during iron-fertilized blooms.

  12. Postinflationary Higgs Relaxation and the Origin of Matter-Antimatter Asymmetry

    NASA Astrophysics Data System (ADS)

    Kusenko, Alexander; Pearce, Lauren; Yang, Louis

    2015-02-01

    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.

  13. 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. PMID:25723202

  14. 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.

  15. 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.

  16. Oxygen isotope studies of ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Clayton, Robert N.; Mayeda, Toshiko K.; Olsen, Edward J.; Goswami, J. N.

    1991-01-01

    Several stages in the evolution of ordinary chondritic meteorites are recorded in the oxygen isotopic composition of the meteorites and their separable components (chondrules, fragments, clasts, and matrix). The whole-rock isotopic compositions reflect the iron-group of the meteorite (H, L, or LL). Isotopic uniformity of H3 to H6 and L3 to L6 are consistent with closed-system metamorphism within each parent body. LL3 chondrites differ slightly from LL4 to LL6, implying a small degree of open-system aqueous alteration and carbon reduction. On the scale of individual chondrules, the meteorites are isotopically heterogeneous, allowing recognition of the solar-nebular processes of chondrule formation. Chondrules for all classes of ordinary chondrites are derived from a common population, which was separate from the population of chondrules in carbonaceous or enstatite chondrites. Chondrules define an isotopic mixing line dominated by exchange between (O - 16)-rich and (O - 16)-poor reservoirs. The oxygen isotopic compositions of chondrites serve as 'fingerprints' for identification of genetic association with other meteorite types (achondrites and iron) and for recognition of source materials in meteoritic breccias.

  17. Reclassification and thermal history of Trenzano chondrite

    NASA Astrophysics Data System (ADS)

    Fioretti, A. M.; Domeneghetti, M. C.; Molin, G.; Cámara, F.; Alvaro, M.; Agostini, L.

    We present a new single-crystal X-ray diffraction (XRD) study performed on a suite of six orthopyroxene grains from the low-shocked H6 Trenzano meteorite. The quenched intracrystalline Fe2+-Mg ordering state in orthopyroxene preserves the memory of the cooling rate near closure temperature Tc, thus yielding useful constraints on the last thermal event undergone by the host rock. The orthopyroxene Tc of 522 ± 13 °C, calculated using a new calibration equation obtained by Stimpfl (2005b), is higher than in previously published H chondrite data. The orthopyroxene cooling rate at this Tc is about 100 °C/kyr. This fast rate is inconsistent with the much slower cooling rate expected for H6 in the onion shell structural and thermal model of chondrite parent bodies. A petrographic study carried out at the same time indicated that the Trenzano meteorite is an H5 chondrite and not an H6 chondrite, as it is officially classified. Furthermore, the two-pyroxene equilibrium temperature of Trenzano (824 ± 24 °C), calculated with QUILF95, is similar to the two-pyroxene temperature of 750-840 °C obtained for the Carcote (H5) chondrite (Kleinschrot and Okrusch 1999).

  18. 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.

  19. 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.

  20. 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.

  1. Mean Atomic Weight of Chelyabinsk and Olivenza LL5 Chondrites

    NASA Astrophysics Data System (ADS)

    Szurgot, M.

    2015-07-01

    Mean atomic weights (Amean) of Chelyabinsk and Olivenza LL5 chondrites have been determined and analysed. Relationship between Fe/Si atomic ratio and mean atomic weight of ordinary chondrites has been established which enables one to predict Amean values.

  2. Quantum origin of pre-big-bang collapse from induced matter theory of gravity

    NASA Astrophysics Data System (ADS)

    Bellini, Mauricio

    2012-03-01

    We revisit a collapsing pre-big-bang model of the universe to study with detail the non-perturbative quantum dynamics of the dispersal scalar field whose dynamics becomes from the dynamical foliation of test massless scalar field φ on a 5D Riemann-flat metric, such that the extra space-like coordinate is noncompact. The important result here obtained is that the evolution of the system, which is described thorough the equation of state has the unique origin in the quantum contributions of the effective 4D scalar field φ¯.

  3. 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

  4. 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.

    2016-07-01

    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.

  5. 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.

  6. Life origination hydrate hypothesis (LOH-hypothesis): What markers testify to the possibility of the living-matter occurrence at exoplanets?

    NASA Astrophysics Data System (ADS)

    Kadyshevich, E. A.; Ostrovskii, V. E.

    2011-10-01

    The markers that testify to the possibility of the living matter occurrence at exoplanets are considered in the context of the thermodynamically-grounded Life Origination Hydrate Hypothesis (LOHhypothesis). Just formation of DNAs from minerals is the key factor that makes possible origination of living matter; proteins are the side products of DNAs interaction with environment and of replication. DNAs and proto-cells originated under ground and (or) under seabed at 270 ± 20 K in solid ice medium from CH4 (or CH4-hydrocarbons), niter, and phosphate with liberation of O2, N2, and, possibly, NH3. Just the occurrence of these gases and their combinations in the planetary atmosphere and the above-specified underground temperature are the markers of the possible occurrence of living matter. CH4 formed from CO2 and H2 or is of nebular origin.

  7. 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.

  8. 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

  9. 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.

  10. 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

  11. Occurrence and Characterization of Steroid Growth Promoters Associated with Particulate Matter Originating from Beef Cattle Feedyards.

    PubMed

    Blackwell, Brett R; Wooten, Kimberly J; Buser, Michael D; Johnson, Bradley J; Cobb, George P; Smith, Philip N

    2015-07-21

    Studies of steroid growth promoters from beef cattle feedyards have previously focused on effluent or surface runoff as the primary route of transport from animal feeding operations. There is potential for steroid transport via fugitive airborne particulate matter (PM) from cattle feedyards; therefore, the objective of this study was to characterize the occurrence and concentration of steroid growth promoters in PM from feedyards. Air sampling was conducted at commercial feedyards (n = 5) across the Southern Great Plains from 2010 to 2012. Total suspended particulates (TSP), PM10, and PM2.5 were collected for particle size analysis and steroid growth promoter analysis. Particle size distributions were generated from TSP samples only, while steroid analysis was conducted on extracts of PM samples using liquid chromatography mass spectrometry. Of seven targeted steroids, 17α-estradiol and estrone were the most commonly detected, identified in over 94% of samples at median concentrations of 20.6 and 10.8 ng/g, respectively. Melengestrol acetate and 17α-trenbolone were detected in 31% and 39% of all PM samples at median concentrations of 1.3 and 1.9 ng/g, respectively. Results demonstrate PM is a viable route of steroid transportation and may be a significant contributor to environmental steroid hormone loading from cattle feedyards. PMID:26098147

  12. Light dark matter, naturalness, and the radiative origin of the electroweak scale

    DOE PAGESBeta

    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 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. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. 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

  19. 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

  20. Origin-Oriented Elemental Profile of Fine Ambient Particulate Matter in Central European Suburban Conditions.

    PubMed

    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

  1. A simple chondritic model of Mars

    NASA Astrophysics Data System (ADS)

    Sanloup, C.; Jambon, A.; Gillet, P.

    1999-03-01

    SNC meteorites (Shergottites, Nakhlites and Chassigny) define a fractionation line in a δ 17O/δ 18O diagram as expected for rocks differentiated from a formerly homogenized parent body, which is intermediate between H ordinary chondrites and EH enstatite chondrites. The planet Mars is located between the Earth and the asteroid belts, the potential source of ordinary chondrites. Since oxygen is a major component of the terrestrial planets, our model assumes that Mars composition is a mixture of two chondritic sources whose proportions are calculated by mass balance based on oxygen isotopes only. Two possible model compositions can be derived: if the average isotopic composition of SNC is relaxed along its fractionation line (Model 1) and if the end members are average H and EH chondrites, one obtains a 30:70 H:EH mixture. If the average isotopic composition of SNC is a robust feature, then an extreme composition of H chondrites must be selected which yields the proportion, 55:45 for the H:EH components. This composition carries the same oxygen isotopic composition as the iron inclusions in the IIE of the conjectured end member of the ordinary chondrite group. The proportions obtained this way enable to calculate two model compositions for all the refractory elements and oxygen. Model 1 can be discarded as it does not permit to fit reasonably the physical properties of the planet. Mass and composition of the core (Model 2) is easily derived (23% of Mars mass, containing 16% S); the remainder forming the bulk mantle composition. Comparison with recent estimates based on the composition of SNC meteorites reveals only minor differences, essentially for Si, Mg and Fe; this is because of our choice of non-CI chondritic composition, unlike previous models. Discussion of the assumptions made in previous models confirms that the new composition is in agreement with the SNC compositions. The model also permits to calculate adequate physical properties of the planet like its

  2. 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.

  3. 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.

  4. 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].

  5. 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.

  6. 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.

  7. 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.

  8. 16O excesses in olivine inclusions in Yamato-86009 and Murchison chondrites and their relation to CAIs.

    PubMed

    Hiyagon, H; Hashimoto, A

    1999-02-01

    In situ ion microprobe analyses of oxygen isotopes in Yamato-86009 and Murchison chondrites show that they contain abundant olivine-rich inclusions that have large oxygen-16 (16O) excesses, similar to those in spinel grains in calcium-aluminium-rich inclusions in Allende and other carbonaceous chondrites. The existence of 16O-enriched olivine-rich inclusions suggests that oxygen isotopic anomalies were more extensive in the early solar system than was previously thought and that their origin may be attributed to a nebular chemical process rather than to an unidentified 16O-rich carrier of presolar origin. PMID:9933162

  9. 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. PMID:21982630

  10. Metallic Fractions of Ordinary Chondrites: Implications to the Structure of Chondritic Parent Bodies

    NASA Astrophysics Data System (ADS)

    Ebihara, M.; Kong, P.

    1995-09-01

    Bulk metal and taenite fractions separated by a chemical method [1] from 23 ordinary chondrites were studied by INAA and Mossbauer spectroscopy. The elemental distributions demonstrate that siderophile elements, except Co and possibly As and Mo, are more enriched in taenite than kamacite but with different abundance ratios between them. Apparently, kamacite and taenite are not produced by redox reactions, condensation fractionation and melt-solid fractionation. Instead, kamacite and taenite can only be the equilibrated products by low temperature diffusion following the Fe-Ni phase diagram. Positive correlation of Co and Ni in carbonaceous chondritic metals and the existence of a high Co and low Ni metal phase in some LL chondrites suggest that chondritic kamacite and taenite can not be developed in the nebula. Rather, kamacite and taenite are produced through solid diffusion in the chondritic parent bodies. There is a large difference in the development of kamacite and taenite between the equilibrated and the unequilibrated L chondrites: the taenite phase of the unequilibrated L chondrites is mostly or totally developed into tetrataenite while low-Ni paramagnetic taenite is still present abundantly in the equilibrated L chondrites. The low-Ni paramagnetic taenite is believed to be an unequilibrated phase of either an incompletely transformed phase during fast cooling [2] or a metastable taenite located out of the miscibility gap on the Fe-Ni phase diagram [3]. In either case, the arrangement of the EOCs and the UOCs in the parent body was the same; the EOCs located near the surface of the parent body, with the UOCs being near the center, if they derived from the common parent body. An intrinsic thermal activity in the parent body would produce a temperature gradient decreasing from the center to the surface, whereas an external heating would exhibit the inverse trend. If a "reverse" onion shell structure is invoked, the generally accepted metamorphic temperatures

  11. 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. PMID:27521951

  12. 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.

  13. 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.

  14. Origin and fate of particulate and dissolved organic matter in a naturally iron-fertilized region of the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Tremblay, L.; Caparros, J.; Leblanc, K.; Obernosterer, I.

    2015-01-01

    Natural iron fertilization of high-nutrient low-chlorophyll (HNLC) waters induces annually occurring spring phytoplankton blooms off the Kerguelen Islands (Southern Ocean). To examine the origin and fate of particulate and dissolved organic matter (POM and DOM), D- and L-amino acids (AA) were quantified at bloom and HNLC stations. Total hydrolyzable AA accounted for 21-25% of surface particulate organic carbon (%POCAA) at the bloom sites, but for 10% at the HNLC site. A marked decrease in %POCAA with depth was observed at the most productive stations leading to values between 3 and 5% below 300 m depth. AA contributed to only 0.9-4.4% of dissolved organic carbon (%DOCAA) at all stations. The only consistent vertical trend was observed at the most productive station (A3-2) where %DOCAA decreased from ~ 2% in the surface waters to 0.9% near 300 m. These AA yields revealed that POM and DOM were more rapidly altered or mineralized at the bloom sites compared to the HNLC site. Alteration state was also assessed by trends in C / N ratio, %D-AA and degradation index. Different molecular markers indicated that POM mostly originated from diatoms and bacteria. The estimated average proportion of POM from intact phytoplankton cells in surface waters was 45% at the bloom station A3-2, but 14% at the HNLC site. Estimates based on D-AA yields indicated that ~ 15% of POM and ~ 30% of DOM was of bacterial origin (cells and cell fragments) at all stations. Surprisingly, the DOM in HNLC waters appeared less altered than the DOM from the bloom, had slightly higher dissolved AA concentrations, and showed no sign of alteration within the water column. Unfavorable conditions for bacterial degradation in HNLC regions can explain these findings. In contrast, large inputs of labile organic molecules and iron likely stimulate the degradation of organic matter (priming effect) and the production of more recalcitrant DOM (microbial carbon pump) during iron-fertilized blooms.

  15. 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

  16. 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

  17. Collisional records in LL-chondrites

    NASA Technical Reports Server (NTRS)

    Graf, Thomas; Marti, Kurt

    1994-01-01

    One third of all the LL-chondrites have exposure ages of approx. 15 Ma and were exposed to cosmic rays following a collisional break-up. The probability that the 15-Ma peak represents a random signal is calculated to be less than 2%. Considerably lower probabilities are obtained if only LL5s or subgroups of high Ar-40 retention are used. Furthermore, we show that the peak shape agrees with statistical constraints obtained from multiple analyses of samples from the St. Severin LL6-chondrites. The frequency in and out of the 15-Ma peak varies significantly for different petrographic LL-types. The radiogenic Ar-40 retention systematics (most LL-chondrites retained Ar-40(sub rad) shows that no substantial heat pulse resulted in the 15-Ma collisional event. Interestingly, smaller exposure age clusters at approx. 28 Ma and approx. 40 Ma match up well with clusters in the histogram of L-chondrites. The distribution of LL-exposure ages is not consistent with that expected for a quasi-continuous injection of LL material into a resonance zone of the asteroid belt. The near absence of exposure ages shorter than 8 Ma either indicates a lack of recent collisional events or considerably longer transfer times than inferred from dynamical considerations.

  18. Spectrum of carbonaceous-chondrite fission xenon

    NASA Technical Reports Server (NTRS)

    Clayton, D. D.

    1976-01-01

    Estimations of the fission spectrum in xenon isotopes from the progenitor of the strange carbonaceous-chondrite xenon must take account of p-process nucleosynthesis if the latter is the source of anomalous Xe-124, 126. Sample calculations of the p-process yields illustrate the magnitude of the effect, which can greatly increase the estimated Xe-132 fission yield.

  19. 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.

  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. Intensive parameters of enstatite chondrite metamorphism

    NASA Astrophysics Data System (ADS)

    Fogel, R. A.; Hess, P. C.; Rutherford, M. J.

    1989-10-01

    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.

  2. 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.

  3. 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.

  4. 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 in situ observations of 5-50μm spherical carbonaceous structures in the Tissint Martian meteorite comprising of pyrite (FeS2) cores and carbonaceous outer coatings. The structures are characterized as smooth immiscible spheres with curved boundaries occasionally following the contours of the pyrite inclusion. The structures bear striking resemblance to similar-sized immiscible carbonaceous spheres found in hydrothermal calcite vein deposits in the Mullaghwornia Quarry in central Ireland. Similar structures have been reported in Proterozoic and Ordovician sandstones from Canada as well as in a variety of astronomical sources including carbonaceous chondrites, chondritic IDPs and primitive chondritic meteorites. SEM and X-Ray elemental mapping confirmed the presence of organic carbon filling the crack and cleavage space in the pyroxene substrate, with further evidence of pyrite acting as an attractive substrate for the collection of organic matter. The detection of precipitated carbon collecting around pyrite grains is at variance with an igneous origin as proposed for the reduced organic component in Tissint, and is more consistent with a biogenetic origin.

  5. Correlated Alteration Effects in CM Carbonaceous Chondrites

    NASA Astrophysics Data System (ADS)

    Zolensky, Michael E.; Browning, Lauren B.; McSween, Harry Y., Jr.

    1996-01-01

    Three parameters are proposed to determine the relative extent of alteration in CM chondrites. The mineralogic alteration index monitors the relative progress of coupled substitutions in the progressive alteration of cronstedtite to Mg-serpentine, and increases with increasing alteration. To calculate values of this index, an algorithm has been developed to estimate the average matrix phyllosilicate composition in individual CM chondrites. The second parameter is the volume percent of isolated matrix silicates, which decreases with progressive alteration due to mineral hydration. Finally, the volume percent of chondrule alteration monitors the extent of chondrule phyllosilicate production, and increases as alteration proceeds. These parameters define the first CM alteration scale that-relies on multiple indicators of progressive alteration. The following relative order of increasing alteration is established by this model: Murchison less than or equal to Bells less than Pollen less than or equal to Murray less than Mighei less than Nogoya less than Cold Bokkeveld. Bulk delta18O values generally increase with progressive alteration, providing additional support for this sequence. The relative degree of aqueous processing Cochabamba and Boriskino experienced is less precisely constrained, although both fall near the middle of this sequence. A comparison between the mineralogic alteration index and literature values of the whole-rock chemistry of CM chondrites reveals several correlations. For example, a positive, nearly linear correlation between bulk H content and progressive CM alteration suggests an approximately constant production rate of new phyllosilicates relative to the mineralogical transition from cronstedtite to Mg-serpentine. Furthermore, the abundance of trapped planetary Ar-36 decreases systematically in progressively altered CM chondrites, suggesting the wholesale destruction of primary noble gas carrier phase(s) by aqueous reactions. Multiple

  6. The great 8 MA event and the structure of the H-chondrite parent body

    NASA Technical Reports Server (NTRS)

    Benoit, P. H.; Sears, D. W. G.

    1993-01-01

    The H-chondrites have been the subject of several recent controversies, including the question of whether Antarctic and non-Antarctic meteorites are or are not the same and whether there or is not evidence for stratigraphic layering in the original parent body. We have identified two distinct groups of H5 chondrites in the Antarctic collection. One group has induced thermoluminescence (TL) peak temperatures less than 190 C and metallographic cooling rates between S to 50 K/Myr, similar to modern falls. It also has a variety of cosmic ray exposure ages, many being greater than 107 years. The other group has TL peak temperatures greater than 190 C, metallographic cooling rates of 100 K/Myr and cosmic ray exposure ages of 8 Ma. The members of this group were generals smaller than those of the greater than 190 C group (including the mode falls) during cosmic ray exposure. Detailed study of the cosmogenic nuclide concentrations of these groups indicates that they are not solely the result of pairing of a few unusual meteorites. It is likely that the greater than 190 C group was an important part of the H-chondrite flux about 1 million years ago, but has since decreased in importance relative to the less than 190 C group. In a previous work, we discussed several possible origins for the greater than 190 C group, including multiple H-chondrite parent bodies, unusual parent body structure, and creation during the 8 Ma event. In this paper, we present new data for H4 chondrites in light of these ideas.

  7. Pb-Pb dating of individual chondrules from the CBa chondrite Gujba: Assessment of the impact plume formation model

    PubMed Central

    Bollard, Jean; Connelly, James N.; Bizzarro, Martin

    2016-01-01

    The CB chondrites are metal-rich meteorites with characteristics that sharply distinguish them from other chondrite groups. Their unusual chemical and petrologic features and a young formation age of bulk chondrules dated from the CBa chondrite Gujba are interpreted to reflect a single-stage impact origin. Here, we report high-precision internal isochrons for four individual chondrules of the Gujba chondrite to probe the formation history of CB chondrites and evaluate the concordancy of relevant short-lived radionuclide chronometers. All four chondrules define a brief formation interval with a weighted mean age of 4562.49 ± 0.21 Myr, consistent with its origin from the vapor-melt impact plume generated by colliding planetesimals. Formation in a debris disk mostly devoid of nebular gas and dust sets an upper limit for the solar protoplanetary disk lifetime at 4.8 ± 0.3 Myr. Finally, given the well-behaved Pb-Pb systematics of all four chondrules, a precise formation age and the concordancy of the Mn-Cr, Hf-W, and I-Xe short-lived radionuclide relative chronometers, we propose that Gujba may serve as a suitable time anchor for these systems. PMID:27429545

  8. A corundum-rich inclusion in the Murchison carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Bar-Matthews, M.; Hutcheon, I. D.; MacPherson, G. J.; Grossman, L.

    1982-01-01

    Although thermodynamic calculations predict corundum to be the first condensate from a cooling gas of solar composition, a corundum-hibonite inclusion, BB-5, has for the first time been found in the Murchison carbonaceous chondrite. Ion microprobe measurements of Mg isotopic compositions yield the result, unexpected in such an early condensate, that Mg-26 excesses are small despite large Al-27/Mg-24 ratios. The extreme temperature required to melt this inclusion makes a liquid origin unlikely, except by the hypervelocity impact of refractory bodies. Alternatively, B-5 is a direct gas-solid condensate, and its uniform Mg-26 enrichment must be a characteristic of the reservoir from which it condensed. Nebular heterogeneity in magnesium isotopic composition is the preferred explanation for the formation of such a reservoir.

  9. Nucleosynthetic strontium isotope anomalies in carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Yokoyama, Tetsuya; Fukami, Yusuke; Okui, Wataru; Ito, Nobuaki; Yamazaki, Hiroshi

    2015-04-01

    Precise Sr isotopic compositions in samples from sequential acid leaching experiments have been determined for three carbonaceous chondrites, Allende, Murchison, and Tagish Lake, together with those in the bulk aliquots of these meteorites. The chondritic acid leachates and residues were characterized by Sr isotope anomalies with variable μ84Sr values (106 relative deviation from a standard material) ranging from +120 to - 4700 ppm, documenting multiple nucleosynthetic sources within a single meteorite. In addition, the μ84Sr patterns across leaching samples for individual chondrites differed from one another. The highest μ84Sr values were observed for leaching Step 3 (HCl+H2O, 75 °C) for Allende and Murchison likely because of the incorporation of calcium and aluminum-rich inclusions (CAIs). In contrast, extremely low μ84Sr values were observed in the later fractions (Steps 6 and 7) for Murchison and Tagish Lake, suggesting the existence of s-process-enriched presolar SiC grains derived from AGB stars. A μ84Sr-ɛ54Cr diagram was prepared with the CAIs and bulk aliquots of carbonaceous chondrites and other meteorites (noncarbonaceous) that were plotted separately; however, they still formed a global positive correlation. CAIs presented the highest μ84Sr and ɛ54Cr values, whereas carbonaceous chondrites and noncarbonaceous meteorites had intermediate and the lowest μ84Sr and ɛ54Cr values, respectively. The positive trend was interpreted as resulting from global thermal processing in which sublimation of high μ84Sr and ɛ54Cr carriers generated the excess μ84Sr and ɛ54Cr signatures in CAIs, while noncarbonaceous planetesimals accreted from materials that underwent significant thermal processing and thus had relatively low μ84Sr and ɛ54Cr values. Apart from the global trend, the carbonaceous chondrites and noncarbonaceous meteorites both exhibited intrinsic variations that highlight an isotopic dichotomy similar to that observed in other isotope

  10. Origin of magnetite and pyrrhotite in carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

    It is proposed that a substantial fraction of the magnetite, at least, resulted from the oxidation of troilite. Pyrrhotite is expected as a direct consequence of magnetite formation through this reaction. During thermomagnetic experiments on troilite, magnetite formation was observed at temperatures as low as 373 K, provided that the oxygen fugacity was held in the magnetite stability field, and that the troilite was sufficiently finely divided.

  11. Detection of monomethylarsenic compounds originating from pesticide in airborne particulate matter sampled in an agricultural area in Japan

    NASA Astrophysics Data System (ADS)

    Mukai, Hitoshi; Ambe, Yoshinari

    Alkylarsenic species in airborne particulate matter sampled in an agricultural area in Japan were investigated. The monomethyl form of arsenic, which has not been found so far in the air, was detected in a concentration as much as 1.4 ng m -3 in a sample collected on a sunny summer day. It had a different size distribution from that of di- and tri-methyl forms of arsenic. The mean particle diameter containing monomethylarsenic compound was 2-4 μm, while those of the di- and/or tri-methyl forms of arsenic were 0.2-0.5 μm. This monomethyl form is thought to originate from the alkylarsenic pesticide spread over rice fields, based on the relation between variation in its concentration and meteorological conditions. Alkylarsenic pesticide appears to be blown up by the wind when the land surface is dry. Further, the methylation of arsenic in nature was found to be influenced by humidity and temperature.

  12. Supersymmetric origin of matter

    SciTech Connect

    Balazs, C.; Carena, M.; Menon, A.; Morrissey, D.E.; Wagner, C.E.M.

    2005-04-01

    The minimal supersymmetric extension of the standard model (MSSM) can provide the correct neutralino relic abundance and baryon number asymmetry of the universe. Both may be efficiently generated in the presence of CP violating phases, light charginos and neutralinos, and a light top squark. Because of the coannihilation of the neutralino with the light stop, we find a large region of parameter space in which the neutralino relic density is consistent with WMAP and SDSS data. We perform a detailed study of the additional constraints induced when CP violating phases, consistent with the ones required for baryogenesis, are included. We explore the possible tests of this scenario from present and future electron electric dipole moment (EDM) measurements, direct neutralino detection experiments, collider searches and the b{yields}s{gamma} decay rate. We find that the EDM constraints are quite severe and that electron EDM experiments, together with stop searches at the Tevatron and Higgs searches at the LHC, will provide a definite test of our scenario of electroweak baryogenesis in the next few years.

  13. Microbial Origin and Transformation of Dissolved Organic Matter in the Agricultural Willow Slough Watershed, California: Insights From Amino Sugars

    NASA Astrophysics Data System (ADS)

    Journet, S.; Pellerin, B. A.; Bergamaschi, B. A.; Hernes, P. J.

    2007-12-01

    Understanding the fundamental processes and land management practices affecting dissolved organic matter (DOM) cycling in agricultural watersheds is essential for managing drinking water quality and maintaining ecosystem health. Although dissolved organic nitrogen (DON) is increasingly recognized as a key component of DOM in disturbed watersheds, our knowledge of its origin and reactivity are limited due to multiple sources, microbial uptake, and secondary production. In particular, the effect of microbial processes on DON dynamics remains poorly understood at the watershed scale. The seasonal and spatial variations of DON concentrations in the surface waters of the Willow Slough watershed, a 425-km2 agriculturally-dominated catchment in the northern Central Valley of California, USA, were monitored weekly at 8 locations since January 2006. Amino sugars are specific microbial biomarkers and their unique distribution among groups of microorganisms such as bacteria, fungi, and algae allows the distinction between different sources of DOM. Although mean annual DON concentrations were lower at the headwaters (0.18 mg/L) than the outlet (0.45 mg/L), DON constituted up to 90% of the total dissolved nitrogen (TDN) at the headwaters, compared to only 15% of the TDN at the watershed outlet. During winter baseflows, DON concentrations at the outlet were low (0.2 mg/L), while they increased to about 1.2 mg/L during winter storms. Remarkably, DON concentrations increased and remained high at 0.6 mg/L during the summer irrigation season. Preliminary data suggests that winter storm runoff and summer irrigation flows are dominated by DON of terrestrial origin, whereas periods of winter baseflow are mainly composed of algal-derived DON. The concentration of total dissolved amino sugars in the Willow Slough surface waters and the contribution of amino sugars to the DON pool (% DON-AS) will be used to evaluate DON composition and degradation state. In addition, molar ratios of four

  14. Magnetic Evidence for a Partially Differentiated Carbonaceous Chondrite Parent Body and Possible Implications for Asteroid 21 Lutetia

    NASA Astrophysics Data System (ADS)

    Weiss, Benjamin; Carporzen, L.; Elkins-Tanton, L.; Shuster, D. L.; Ebel, D. S.; Gattacceca, J.; Binzel, R. P.

    2010-10-01

    The origin of remanent magnetization in the CV carbonaceous chondrite Allende has been a longstanding mystery. The possibility of a core dynamo like that known for achondrite parent bodies has been discounted because chondrite parent bodies are assumed to be undifferentiated. Here we report that Allende's magnetization was acquired over several million years (Ma) during metasomatism on the parent planetesimal in a > 20 microtesla field 8-9 Ma after solar system formation. This field was present too recently and directionally stable for too long to have been the generated by the protoplanetary disk or young Sun. The field intensity is in the range expected for planetesimal core dynamos (Weiss et al. 2010), suggesting that CV chondrites are derived from the outer, unmelted layer of a partially differentiated body with a convecting metallic core (Elkins-Tanton et al. 2010). This suggests that asteroids with differentiated interiors could be present today but masked under chondritic surfaces. In fact, CV chondrites are spectrally similar to many members of the Eos asteroid family whose spectral diversity has been interpreted as evidence for a partially differentiated parent asteroid (Mothe-Diniz et al. 2008). CV chondrite spectral and polarimetric data also resemble those of asteroid 21 Lutetia (e.g., Belskaya et al. 2010), recently encountered by the Rosetta spacecraft. Ground-based measurements of Lutetia indicate a high density of 2.4-5.1 g cm-3 (Drummond et al. 2010), while radar data seem to rule out a metallic surface composition (Shepard et al. 2008). If Rosetta spacecraft measurements confirm a high density and a CV-like surface composition for Lutetia, then we propose Lutetia may be an example of a partially differentiated carbonaceous chondrite parent body. Regardless, the very existence of primitive achondrites, which contain evidence of both relict chondrules and partial melting, are prima facie evidence for the formation of partially differentiated bodies.

  15. STARDUST INVESTIGATION INTO THE CR CHONDRITE GROVE MOUNTAIN 021710

    SciTech Connect

    Zhao Xuchao; Lin Yangting; Floss, Christine; Bose, Maitrayee

    2013-05-20

    We report the presolar grain inventory of the CR chondrite Grove Mountain 021710. A total of 35 C-anomalous grains ({approx}236 ppm) and 112 O-anomalous grains ({approx}189 ppm) were identified in situ using NanoSIMS ion imaging. Of 35 C-anomalous grains, 28 were determined to be SiC grains by Auger spectroscopy. Seven of the SiC grains were subsequently measured for N and Si isotopes, allowing classification as one nova grain, one Y grain, one Z grain, and four mainstream grains. Eighty-nine out of 112 O-anomalous grains belong to Group 1, indicating origins in low-to-intermediate-mass red giant and asymptotic giant branch stars. Twenty-one are Group 4 grains and have origins in supernovae. Auger spectroscopic elemental measurements of 35 O-anomalous grains show that 33 of them are ferromagnesian silicates. They have higher Mg/(Mg+Fe) ratios than those reported in other meteorites, suggesting a lower degree of alteration in the nebula and/or asteroid parent bodies. Only two oxide grains were identified, with stoichiometric compositions of MgAl{sub 2}O{sub 4} and SiO{sub 2}, respectively. The presolar silicate/oxide ratio of GRV 021710 is comparable with those of the CR3 chondrites (QUE 99177 and MET 00426) and primitive interplanetary dust particles. In order to search for presolar sulfides, the meteorite was also mapped for S isotopes. However, no presolar sulfides were found, suggesting a maximum abundance of 2 ppm. The scarcity of presolar sulfides may be due to their much faster sputtering rate by cosmic rays compared to silicates.

  16. Carbonates and sulfates in CI chondrites - Formation by aqueous activity on the parent body

    NASA Technical Reports Server (NTRS)

    Fredriksson, Kurt; Kerridge, John F.

    1988-01-01

    Compositions and morphologies of dolomites, breunnerites, Ca-carbonates, Ca-sulfates and Mg, Ni, Na-sulfates, and their petrologic interrelations, in four CI chondrites are consistent with their having been formed by aqueous activity on the CI parent body. Radiochronometric data indicate that this activity took place very early in solar-system history. No evidence for original ('primitive') condensates seems to be present. However, alteration apparently took place without change in bulk meteorite composition.

  17. Asteroidal water within fluid inclusion-bearing halite in an H5 chondrite, Monahans (1998)

    NASA Technical Reports Server (NTRS)

    Zolensky, M. E.; Bodnar, R. J.; Gibson, E. K. Jr; Nyquist, L. E.; Reese, Y.; Shih, C. Y.; Wiesmann, H.

    1999-01-01

    Crystals of halite and sylvite within the Monahans (1998) H5 chondrite contain aqueous fluid inclusions. The fluids are dominantly sodium chloride-potassium chloride brines, but they also contain divalent cations such as iron, magnesium, or calcium. Two possible origins for the brines are indigenous fluids flowing within the asteroid and exogenous fluids delivered into the asteroid surface from a salt-containing icy object.

  18. Ar-39/Ar-40 and Space Exposure Ages of the Unique Portales Valley H-Chondrite

    NASA Technical Reports Server (NTRS)

    Garrison, D. H.; Bogard, D. D.

    2001-01-01

    The space exposure age of the unique Portales Valley H-chondrite is approx. 40-45 Myr. The 39 Ar-40 Ar ages of two samples are 4.477 +/- 0.016 and 4.46 +/- 0.02 Ga and show no evidence of more recent disturbance, in contrast to previous radiometric determinations Additional information is contained in the original extended abstract..

  19. Asteroidal water within fluid inclusion-bearing halite in an H5 chondrite, Monahans (1998)

    PubMed

    Zolensky, M E; Bodnar, R J; Gibson, E K; Nyquist, L E; Reese, Y; Shih, C Y; Wiesmann, H

    1999-08-27

    Crystals of halite and sylvite within the Monahans (1998) H5 chondrite contain aqueous fluid inclusions. The fluids are dominantly sodium chloride-potassium chloride brines, but they also contain divalent cations such as iron, magnesium, or calcium. Two possible origins for the brines are indigenous fluids flowing within the asteroid and exogenous fluids delivered into the asteroid surface from a salt-containing icy object. PMID:10464091

  20. Collescipoli - An unusual fusion crust glass. [chondrite

    NASA Technical Reports Server (NTRS)

    Nozette, S.

    1979-01-01

    An electron microprobe study was conducted on glass fragments taken from the fusion crust and an internal glass-lined vein in the H-5 chondrite Collescipoli. Microprobe analyses of the glasses revealed an unusual fusion crust composition, and analyses of glass from inside the meteorite showed compositions expected for a melt of an H-group chondrite. Studies of fusion crusts by previous workers, e.g., Krinov and Ramdohr, showed that fusion crusts contain large amounts of magnetite and other oxidized minerals. The Collescipoli fusion crusts do contain these minerals, but they also contain relatively large amounts of reduced metal, sulphide, and a sodium-rich glass. This study seems to indicate that Collescipoli preserved an early type of fusion crust. Oxidation was incomplete in the fusion crust melt that drained into a crack. From this study it is concluded that fusion crust formation does not invariably result in complete oxidation of metal and sulphide phases.

  1. A Complex Exposure History of the Gold Basin L4-Chondrite Shower from Cosmogenic Radionuclides and Noble Gases

    NASA Technical Reports Server (NTRS)

    Welten, K. C.; Nishiizumi, K.; Caffee, M. W.; Masarik, J.; Wieler, R.

    2001-01-01

    Cosmogenic radionuclides and noble gases in samples of the Gold Basin L-chondrite shower indicate a complex exposure history, with a first stage exposure on the parent body, followed by a second stage of approx. 19 Myr in a meteoroid 3-4 m in radius. Additional information is contained in the original extended abstract.

  2. Cr Isotope Systematics in the Pallasite Eagle Station: Chronology and Evidence for a Genetic Link to Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Shukolyukov, A.; Lugmair, G. W.

    2001-01-01

    The study of the Mn-53-Cr-53 system in the pallasite Eagle Station has shown that it formed 4557.5 +/- 0.6 Ma ago. The Cr isotopic signature is different from that of the main group pallasites and suggests a genetic link to CV3 chondrites. Additional information is contained in the original extended abstract.

  3. Noble Gas Isotopic Signatures and X-Ray and Electron Diffraction Characteristics of Tagish Lake Carbonaceous Chondrite

    NASA Technical Reports Server (NTRS)

    Nakamura, T.; Noguchi, T.; Zolensky, M. E.; Takaoka, N.

    2001-01-01

    Noble gas isotopic signatures and X-ray and electron diffraction characteristics of Tagish Lake indicate that it is a unique carbonaceous chondrite rich in saponite, Fe-Mg-Ca carbonate, primordial noble gases, and presolar grains. Additional information is contained in the original extended abstract.

  4. On the chemical composition of L-chondrites

    NASA Technical Reports Server (NTRS)

    Neal, C. W.; Dodd, R. T.; Jarosewich, E.; Lipschutz, M. E.

    1980-01-01

    Radiochemical neutron activation analysis of Ag, As, Au, Bi, Co, Cs, Ga, In, Rb, Sb, Te, Tl, and Zn and major element data in 14 L4-6 and 3 LL5 chondrites indicates that the L group is unusually variable and may represent at least 2 subgroups differing in formation history. Chemical trends in the S/Fe rich subgroup support textural evidence indicating late loss of a shock formed Fe-Ni-S melt; the S/Fe poor subgroup seemingly reflects nebular fractionation only. Highly mobile In and Zn apparently reflect shock induced loss from L chondrites. However, contrasting chemical trends in several L chondrite sample sets indicate that these meteorites constitute a more irregular sampling of, or more heterogeneous parent material than do carbonaceous or enstatite chondrites. Data for 15 chondrites suggest higher formation temperatures and/or degrees of shock than for LL5 chondrites.

  5. Relative Amino Acid Concentrations as a Signature for Parent Body Processes of Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Botta, Oliver; Glavin, Daniel P.; Kminek, Gerhard; Bada, Jeffrey L.

    2002-01-01

    Most meteorites are thought to have originated from objects in the asteroid belt. Carbonaceous chondrites, which contain significant amounts of organic carbon including complex organic compounds, have also been suggested to be derived from comets. The current model for the synthesis of organic compounds found in carbonaceous chondrites includes the survival of interstellar organic compounds and the processing of some of these compounds on the meteoritic parent body. The amino acid composition of five CM carbonaceous chondrites, two CIs, one CR, and one CV3 have been measured using hot water extraction-vapor hydrolysis, OPA/NAC derivatization and high-performance liquid chromatography (HPLC). Total amino acid abundances in the bulk meteorites as well as the amino acid concentrations relative to glycine = 1.0 for beta-alanine, alpha-aminoisobutyric acid and D-alanine were determined. Additional data for three Antarctic CM meteorites were obtained from the literature. All CM meteorites analyzed in this study show a complex distribution of amino acids and a high variability in total concentration ranging from approx. 15,300 to approx. 5800 parts per billion (ppb), while the CIs show a total amino acid abundance of approx. 4300 ppb. The relatively (compared to glycine) high AIB content found in all the CMs is a strong indicator that Strecker-cyanohydrin synthesis is the dominant pathway for the formation of amino acids found in these meteorites. The data from the Antarctic CM carbonaceous chondrites are inconsistent with the results from the other CMs, perhaps due to influences from the Antarctic ice that were effective during their residence time. In contrast to CMs, the data from the CI carbonaceous chondrites indicate that the Strecker synthesis was not active on their parent bodies.

  6. Late Chondritic Additions and Planet and Planetesimal Growth: Evaluation of Physical and Chemical Mechanisms

    NASA Technical Reports Server (NTRS)

    Righter, Kevin

    2013-01-01

    Studies of terrestrial peridotite and martian and achondritic meteorites have led to the conclusion that addition of chondritic material to growing planets or planetesimals, after core formation, occurred on Earth, Mars, asteroid 4 Vesta, and the parent body of the angritic meteorites [1-4]. One study even proposed that this was a common process in the final stages of growth [5]. These conclusions are based almost entirely on the highly siderophile elements (HSE; Re, Au, Pt, Pd, Rh, Ru, Ir, Os). The HSE are a group of eight elements that have been used to argue for late accretion of chondritic material to the Earth after core formation was complete (e.g., [6]). This idea was originally proposed because the D(metal/silicate) values for the HSE are so high, yet their concentration in the mantle is too high to be consistent with such high Ds. The HSE also are present in chondritic relative abundances and hence require similar Ds if this is the result of core-mantle equilibration. Since the work of [6] there has been a realization that core formation at high PT conditions can explain the abundances of many siderophile elements in the mantle (e.g., [7]), but such detailed high PT partitioning data are lacking for many of the HSE to evaluate whether such ideas are viable for all four bodies. Consideration of other chemical parameters reveals larger problems that are difficult to overcome, but must be addressed in any scenario which calls on the addition of chondritic material to a reduced mantle. Yet these problems are rarely discussed or emphasized, making the late chondritic (or late veneer) addition hypothesis suspect.

  7. Spatial variation in the origin and reactivity of dissolved organic matter in Oregon-Washington coastal waters

    NASA Astrophysics Data System (ADS)

    Lu, YueHan; Edmonds, Jennifer W.; Yamashita, Youhei; Zhou, Bin; Jaegge, Andrea; Baxley, Matthew

    2015-01-01

    Combining stable carbon isotopic signatures (δ13C-DOC) and optical properties of dissolved organic matter (DOM), we examined spatial variability in the sources and reactivity of DOM from Oregon-Washington coastal waters, with a particular focus on evaluating whether these measurements may reliably trace terrigenous DOM in coastal oceans. We sampled four stations on the continental shelf and four stations on the continental slope near the mouth of the Columbia River, with sampling depths ranging from 0 to 1,678 m. Nitrate and phosphate concentrations were largely controlled by organic matter (OM) regeneration although the river plume may have led to excess nitrates in relation to phosphates near the river mouth and/or the surface. Four fluorescence components (C1 to C4) were identified by using excitation emission matrices-parallel factor analysis. C1 and C2 were assigned as humic-like components which represented degraded DOM rather than OM of allochthonous or autochthonous origin. C3 and C4 were both labile, protein-like components representing autochthonous contributions, while C4 was more sensitive to diagenesis. In the shallow water layer (salinity ≤32.5 and depth ≤50 m), the variation in absorption properties (SUVA254 and ɛ280), fluorescence index, freshness index ( β/ α), percent fluorescence of C3, and δ13C-DOC revealed that the Columbia River plume exported DOM that was characterized by greater aromaticity, higher molecular weight, and being more decomposed than marine, autochthonous DOM. However, these signatures of terrigenous DOM disappeared rapidly with increasing depth and offshore distance. In the intermediate and deep water layers (salinity >32.5), the DOM indices were most driven by diagenesis, with changes in percent fluorescence components indicating increasing accumulation of humic DOM relative to protein-like DOM with depth. Principal component analysis that collectively assessed the DOM indices suggests that diagenesis was the primary

  8. Isotopic evidence for primordial molecular cloud material in metal-rich carbonaceous chondrites

    PubMed Central

    Van Kooten, Elishevah M. M. E.; Wielandt, Daniel; Schiller, Martin; Nagashima, Kazuhide; Thomen, Aurélien; Olsen, Mia B.; Nordlund, Åke; Krot, Alexander N.; Bizzarro, Martin

    2016-01-01

    The short-lived 26Al radionuclide is thought to have been admixed into the initially 26Al-poor protosolar molecular cloud before or contemporaneously with its collapse. Bulk inner Solar System reservoirs record positively correlated variability in mass-independent 54Cr and 26Mg*, the decay product of 26Al. This correlation is interpreted as reflecting progressive thermal processing of in-falling 26Al-rich molecular cloud material in the inner Solar System. The thermally unprocessed molecular cloud matter reflecting the nucleosynthetic makeup of the molecular cloud before the last addition of stellar-derived 26Al has not been identified yet but may be preserved in planetesimals that accreted in the outer Solar System. We show that metal-rich carbonaceous chondrites and their components have a unique isotopic signature extending from an inner Solar System composition toward a 26Mg*-depleted and 54Cr-enriched component. This composition is consistent with that expected for thermally unprocessed primordial molecular cloud material before its pollution by stellar-derived 26Al. The 26Mg* and 54Cr compositions of bulk metal-rich chondrites require significant amounts (25–50%) of primordial molecular cloud matter in their precursor material. Given that such high fractions of primordial molecular cloud material are expected to survive only in the outer Solar System, we infer that, similarly to cometary bodies, metal-rich carbonaceous chondrites are samples of planetesimals that accreted beyond the orbits of the gas giants. The lack of evidence for this material in other chondrite groups requires isolation from the outer Solar System, possibly by the opening of disk gaps from the early formation of gas giants. PMID:26858438

  9. Isotopic evidence for primordial molecular cloud material in metal-rich carbonaceous chondrites.

    PubMed

    Van Kooten, Elishevah M M E; Wielandt, Daniel; Schiller, Martin; Nagashima, Kazuhide; Thomen, Aurélien; Larsen, Kirsten K; Olsen, Mia B; Nordlund, Åke; Krot, Alexander N; Bizzarro, Martin

    2016-02-23

    The short-lived (26)Al radionuclide is thought to have been admixed into the initially (26)Al-poor protosolar molecular cloud before or contemporaneously with its collapse. Bulk inner Solar System reservoirs record positively correlated variability in mass-independent (54)Cr and (26)Mg*, the decay product of (26)Al. This correlation is interpreted as reflecting progressive thermal processing of in-falling (26)Al-rich molecular cloud material in the inner Solar System. The thermally unprocessed molecular cloud matter reflecting the nucleosynthetic makeup of the molecular cloud before the last addition of stellar-derived (26)Al has not been identified yet but may be preserved in planetesimals that accreted in the outer Solar System. We show that metal-rich carbonaceous chondrites and their components have a unique isotopic signature extending from an inner Solar System composition toward a (26)Mg*-depleted and (54)Cr-enriched component. This composition is consistent with that expected for thermally unprocessed primordial molecular cloud material before its pollution by stellar-derived (26)Al. The (26)Mg* and (54)Cr compositions of bulk metal-rich chondrites require significant amounts (25-50%) of primordial molecular cloud matter in their precursor material. Given that such high fractions of primordial molecular cloud material are expected to survive only in the outer Solar System, we infer that, similarly to cometary bodies, metal-rich carbonaceous chondrites are samples of planetesimals that accreted beyond the orbits of the gas giants. The lack of evidence for this material in other chondrite groups requires isolation from the outer Solar System, possibly by the opening of disk gaps from the early formation of gas giants. PMID:26858438

  10. The meteorite Moss - a rare carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Bilet, M.; Roaldset, E.

    2014-07-01

    On July 14, 2006, at about 10:20 a.m. local daylight time (UTC+2), a bright fireball travelling SSE-NNV was witnessed from the Baltic Sea to SE Norway. On the east side of the Oslo fiord, around Moss, an explosion and a rumbling sound was heard, and pieces were observed falling. Rapid recovery of meteorite stones gave an opportunity for detailed petrological and geochemical investigations, including analyses of indigenous organic species, and short lived isotopes. The meteorite is a chondritic stone meteorite, with some carbon (0.21-0.25 wt% C). The cosmic-ray exposure (CRE) age is 14 Ma, i.e. when Moss was ejected from its parent body. Gas retention ages are approximately 3.95x10^9 yr (U/Th/He) and 4.43x10^9 yr (K/Ar), respectively. The meteorite has the official name Moss, and is classified as carbonaceous chondrite type CO3.6. It was the first witnessed fall of a CO3 chondrite since Kainsaz in Russia in 1937.

  11. Size distributions in two porous chondritic micrometeorites

    NASA Technical Reports Server (NTRS)

    Rietmeijer, Frans J. M.

    1993-01-01

    Quantitative size measurements of granular units (GUs), and nm-sized minerals in these units, in two porous chondritic micrometeorites are investigated. The matrix of these micrometeorites consist of loosely packed, 0.1 micron-sized, GUs. These objects were a major component of the solar nebula dust that accreted into protoplanets. The matrix in micrometeorite W7010*A2 has a fractal dimension with a small coefficient that supports efficient sticking of carbon-rich GUs during accretion. The fractal nature of the matrix provides a way to calculate the density using the aggregate size. The resulting very low density for porous chondritic micrometeorites is 0.08-0.14 g/cu cm, which supports the view that they are the solid debris from unconsolidated solar system bodies. Chondritic GUs contain ultrafine olivines, pyroxenes, and sulfides, embedded in hydrocarbons and amorphous carbons. Nanocrystals in the micrometeorites W7010*A2 and U2015*B show log normal size distributions. The high incidence of disk-shaped grains, a changeover from disk-shaped to euhedral grains, the unevolved nature of the size distributions, and multiple populations for grains less than 127 nm in size, are consistent with continuous postaccretion nucleation and growth in amorphous GUs, including coarsening via Ostwald ripening.

  12. Polyhedral Serpentine Grains in CM Chondrites

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    CM chondrites are primitive rocks that experienced aqueous alteration in the early solar system. Their matrices and fine-grained rims (FGRs) sustained the effects of alteration, and the minerals within them hold clues to the aqueous reactions. Sheet silicates are an important product of alteration, and those of the serpentine group are abundant in the CM2 chondrites. Here we expand on our previous efforts to characterize the structure and chemistry of serpentines in CM chondrites and report results on a polyhedral form that is structurally similar to polygonal serpentine. Polygonal serpentine consists of tetrahedral (T) sheets joined to M(2+)-centered octahedral (O) sheets (where (M2+) is primarily Mg(2+) and Fe(2+)), which give rise to a 1:1 (TO) layered structure with a 0.7-nm layer periodicity. The structure is similar to chrysotile in that it consists of concentric lizardite layers wrapped around the fiber axis. However, unlike the rolled-up chrysotile, the tetrahedral sheets of the lizardite layers are periodically inverted and kinked, producing sectors. The relative angles between sectors result in 15- and 30-sided polygons in terrestrial samples.

  13. Are carbonaceous chondrites primitive or processed - A review

    NASA Technical Reports Server (NTRS)

    Mcsween, H. Y., Jr.

    1979-01-01

    According to the results of the present analysis, carbonaceous chondrites are obviously not pristine samples of proto-solar-system condensates. In terms of chemistry, however, these chondrites may represent the most primitive solar system materials known. It appears that the alterations experienced by carbonaceous chondrites were isochemical, or nearly so, so that their bulk compositions have remained practically unchanged, provided that the analyses are representative of large portions of the meteorites.

  14. The Cerro LOS Calvos and La Banderia chondrites

    NASA Astrophysics Data System (ADS)

    Whitlock, Randall; Lewis, Charles F.; Clark, James C.; Moore, Carleton B.

    1991-06-01

    The Cerro los Calvos meteorite is a single stone of 68.5 g found in the Nuevo Mercurio strewn field of Zacatecas, (Mexico). It is an unusual H4 chondrite. Its olivine (Fa12.5) and orthopyroxene (Fs 11.7, Wo 0.8) are reduced relative to typical H chondrites. The La Banderia meteorite of 54.3 g from the same vicinity is an LL5 chondrite of shock classification e.

  15. Penecontemporaneous metamorphism, fragmentation, and reassembly of ordinary chondrite parent bodies

    NASA Technical Reports Server (NTRS)

    Grimm, R. E.

    1985-01-01

    The thermal histories of ordinary chondrites and the canonical internal heating or onion shell models, which predict an inverse relation between the petrologic type of chondrites and the metallographic cooling rate, are reviewed. The thermal and accretional requirements of the 'metamorphosed planetesimal' model proposed by Scott and Rajan (1981) are analyzed, and an alternative model consistent with the metallographic cooling rate constraints is suggested in which ordinary chondrite parent bodies are collisionally fragmented and then rapidly reassembled before metamorphic heat has been dissipated.

  16. Amino acids of the Nogoya and Mokoia carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Cronin, J. R.; Moore, C. B.

    1976-01-01

    Amino acids were found in acid hydrolyzed, hot water extracts of the Nogoya (C2) and Mokoia (C3V) chondrites. About 40 n moles/g of amino acids were found in the Nogoya extract while Mokoia contained less than 1 n mole/g. The amino acid composition of Nogoya differs from that of other C2 chondrites studied earlier. The results from Mokoia are similar to previous data obtained from the C3V chondrite Allende.

  17. Chemical and physical studies of type 3 chondrites. V - The enstatite chondrites

    NASA Astrophysics Data System (ADS)

    Weeks, K. S.; Sears, D. W. G.

    1985-07-01

    The results of instrumental neutron activation analysis of 19 major, minor, and trace elements in three unequilibrated, or type 3, enstatite chondrites (ECs) are reported. Based on these and the literature data, the relationship between the type 3 ECs and the other ECs is discussed. The abundance of siderophile elements in type 3 ECs places them with the EH, rather than EL chondrites. The chalcophile elements are at the low end of EH range. Cr is intermediate between EH and EL. It is suggested that the type 3 ECs are EH chondrites which have suffered small depletions of certain chalcophile elements through the loss of shock-produced removal of these chalcophiles by the formation of sulfurous veins, and not by weathering. The processes responsible for formation of these and other types of ECs are discussed.

  18. Chemistry and oxygen isotopic composition of cluster chondrite clasts and their components in LL3 chondrites

    NASA Astrophysics Data System (ADS)

    Metzler, Knut; Pack, Andreas

    2016-02-01

    Cluster chondrites are characterized by close-fit textures of deformed and indented chondrules, taken as evidence for hot chondrule accretion (Metzler). We investigated seven cluster chondrite clasts from six brecciated LL3 chondrites and measured their bulk oxygen isotopic and chemical composition, including REE, Zr, and Hf. The same parameters were measured in situ on 93 chondrules and 4 interchondrule matrix areas. The CI-normalized REE patterns of the clasts are flat, showing LL-chondritic concentrations. The mean chemical compositions of chondrules in clasts and other LL chondrites are indistinguishable and we conclude that cluster chondrite chondrules are representative of the normal LL chondrule population. Type II chondrules are depleted in MgO, Al2O3 and refractory lithophiles (REE, Zr, Hf) by factors between 0.65 and 0.79 compared to type I chondrules. The chondrule REE patterns are basically flat with slight LREE < HREE fractionations. Many chondrules exhibit negative Eu anomalies while matrix shows a complementary pattern. Chondrules scatter along a correlation line with a slope of 0.63 in the oxygen 3-isotope diagram, interpreted as the result of O-isotope exchange between chondrule melts and 18O-rich nebular components. In one clast, a distinct anticorrelation between chondrule size and δ18O is found, which may indicate a more intense oxygen isotope exchange by smaller chondrules. In some clasts the δ18O values of type I chondrules are correlated with concentrations of SiO2 and MnO and anticorrelated with MgO, possibly due to the admixture of a SiO2- and MnO-rich component to chondrule melts during oxygen isotope exchange. Two chondrules with negative anomalies in Sm, Eu, and Yb were found and may relate their precursors to refractory material known from group III CAIs. Furthermore, three chondrules with strong LREE > HREE and Zr/Hf fractionations were detected, whose formation history remains to be explained.

  19. Chemical and physical studies of type 3 chondrites - VIII: Thermoluminescence and metamorphism in the CO chondrites

    SciTech Connect

    Keck, B.D.; Sears, D.W.G. )

    1987-11-01

    The thermoluminescence properties of nine CO chondrites have been measured. With the exception of Colony and Allan Hills A77307 (ALHA 77307), whose maximum induced TL emission is at approximately 350{degree}C, CO chondrites exhibit two TL peaks, one at 124 {plus minus} 7{degree}C (130{degree}C peak) and one at 252 {plus minus} 7{degree}C (250{degree}C peak). The 130{degree}C peak shows a 100-fold range in TL sensitivity and correlates with various metamorphism-related phenomena, such as silicate heterogeneity, metal composition and McSween's metamorphic subtypes. The peak at 250{degree}C does not show these correlations and, Colony excepted, varies little throughout the class. Mineral separation experiments, and a series of annealing experiments on Isna, suggest that the TL properties for CO chondrites reflect the presence of feldspar in two forms, (1) a form produced during metamorphism, and analogous to the dominant form of feldspar in type 3 ordinary chondrites, and (2) a primary, metamorphism-independent form, perhaps associated with the amoeboid inclusions. If this interpretation is correct, then the CO chondrites have not experienced temperatures above the order/disorder temperature for feldspar (500-600{degree}C) and they cooled more slowly than comparable type 3 ordinary chondrites. Colony and ALHA 77307 have atypical TL properties, including very low TL sensitivity, suggesting that phosphors other than feldspar are important. They have apparently experienced less metamorphism than the others, and may have also been aqueously altered.

  20. The Loop chondrite - Petrology, mineral chemistry, and opaque mineralogy

    NASA Astrophysics Data System (ADS)

    Boctor, N. Z.; Kullerud, G.

    1981-03-01

    The petrography, mineral chemistry, and opaque mineralogy of the Loop chondrite, a meteorite found in Gaines County (Texas) in 1962, are discussed. The investigation confirms Mason's (1975) classification of the meteorite as olivine hypersthene chondrite (L6) and proves that the Loop and the Ashmore are distinct chondrites. Tables setting forth representative analyses of silicates and chromite and of metal and troilite are included. It is found that in comparison with the chromite composition of L6 chondrites given by Bunch et al. (1967), the Loop is slightly more enriched in A12O3 and MgO and slightly depleted in Cr2O3.

  1. The distribution of trace elements in carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Knab, H.-J.

    1981-09-01

    Twelve carbonaceous chondrites, among them representatives of nearly all known petrologic types, were analyzed for twenty trace elements by spark source mass spectrography combined with the isotope dilution method. Data on different element groups (refractory, moderately volatile and volatile) show that the distribution of the trace elements in the carbonaceous chondrites, with the exception of Renazzo, can be well explained by Anders' two-component model. This is also valid for the highly metamorphosed CV5 chondrite Karoonda. Furthermore, it is observed that the Zr/Hf-ratios in the carbonaceous chondrites increase with increasing petrologic type, which is interpreted as the result of mixing two components with different Zr/Hf-ratios.

  2. Graphite-magnetite aggregates in ordinary chondritic meteorites

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    The graphite-magnetite component has been found (1) as abundant isolated inclusions in eight ordinary-chondritic, regolith breccias; (2) as the sole matrix in a new kind of unequilibrated chondrite that forms clasts in these regolith breccias; and (3) together with a Huss matrix in six unequilibrated ordinary chondrites. It is suggested that the component was formed by low-temperature, gas-solid reactions before the accretion of the meteorite, and that the isolated inclusions of graphite-magnetite in regolith breccias were derived from bodies composed of the new kind of chondrite that has graphite-magnetite as its sole matrix.

  3. Graphite-magnetite aggregates in ordinary chondritic meteorites

    NASA Astrophysics Data System (ADS)

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

    1981-06-01

    The graphite-magnetite component has been found (1) as abundant isolated inclusions in eight ordinary-chondritic, regolith breccias; (2) as the sole matrix in a new kind of unequilibrated chondrite that forms clasts in these regolith breccias; and (3) together with a Huss matrix in six unequilibrated ordinary chondrites. It is suggested that the component was formed by low-temperature, gas-solid reactions before the accretion of the meteorite, and that the isolated inclusions of graphite-magnetite in regolith breccias were derived from bodies composed of the new kind of chondrite that has graphite-magnetite as its sole matrix.

  4. Aqueous alteration in the Kaba CV3 carbonaceous chondrite

    NASA Technical Reports Server (NTRS)

    Keller, Lindsay P.; Buseck, Peter R.

    1990-01-01

    Results from TEM and SEM examinations of the Kaba CV3 carbonaceous chondrite are presented, showing that the chondrules and the matrix of Kaba have undergone pervasive low-temperature aqueous alteration, resulting in the formation of Fe-bearing saponite from glass and enstatite in chondrules, and from anhydrous silicates in matrix. The alteration products in Kaba were found to resemble those in other aqueously altered carbonaceous chondrites such as the Mokoia CV3 and in Orgueil CI chondrites and Y-82162 chondrites. However, Kaba lacks the abundant high-Al phyllosilicates, reported for CAIs from Mokoia, and the serpentine and ferrihydrite, found in Orgueil.

  5. Interstellar and Solar System Organic Matter Preserved in Interplanetary Dust

    NASA Astrophysics Data System (ADS)

    Messenger, Scott R.; Nakamura-Messenger, Keiko

    2015-08-01

    Interplanetary dust particles (IDPs) collected in the Earth’s stratosphere derive from collisions among asteroids and by the disruption and outgassing of short-period comets. Chondritic porous (CP) IDPs are among the most primitive Solar System materials. CP-IDPs have been linked to cometary parent bodies by their mineralogy, textures, C-content, and dynamical histories. CP-IDPs are fragile, fine-grained (< um) assemblages of anhydrous amorphous and crystalline silicates, oxides and sulfides bound together by abundant carbonaceous material. Ancient silicate, oxide, and SiC stardust grains exhibiting highly anomalous isotopic compositions are abundant in CP-IDPs, constituting 0.01 - 1 % of the mass of the particles. The organic matter in CP-IDPs is isotopically anomalous, with enrichments in D/H reaching 50x the terrestrial SMOW value and 15N/14N ratios up to 3x terrestrial standard compositions. These anomalies are indicative of low T (10-100 K) mass fractionation in cold molecular cloud or the outermost reaches of the protosolar disk. The organic matter shows distinct morphologies, including sub-um globules, bubbly textures, featureless, and with mineral inclusions. Infrared spectroscopy and mass spectrometry studies of organic matter in IDPs reveals diverse species including aliphatic and aromatic compounds. The organic matter with the highest isotopic anomalies appears to be richer in aliphatic compounds. These materials also bear similarities and differences with primitive, isotopically anomalous organic matter in carbonaceous chondrite meteorites. The diversity of the organic chemistry, morphology, and isotopic properties in IDPs and meteorites reflects variable preservation of interstellar/primordial components and Solar System processing. One unifying feature is the presence of sub-um isotopically anomalous organic globules among all primitive materials, including IDPs, meteorites, and comet Wild-2 samples returned by the Stardust mission. We will present

  6. New pyrolytic and spectroscopic data on Orgueil and Murchison insoluble organic matter: A different origin than soluble?

    NASA Astrophysics Data System (ADS)

    Remusat, Laurent; Derenne, Sylvie; Robert, François; Knicker, Heike

    2005-08-01

    Pyrolysis with and without tetramethylammonium hydroxide (TMAH), vacuum pyrolysis, and solid state 15N nuclear magnetic resonance (NMR) were used to examine the macromolecular insoluble organic matter (IOM) from the Orgueil and Murchison meteorites. Conventional pyrolysis reveals a set of poorly functionalized aromatic compounds, ranging from one to four rings and with random methyl substitutions. These compounds are in agreement with spectroscopic and pyrolytic results previously reported. For the first time, TMAH thermochemolysis was used to study extraterrestrial material. The detection of aromatics bearing methyl esters and methoxy groups reveals the occurrence of ester and ether bridges between aromatic units in the macromolecular network. No nitrogen-containing compounds were detected with TMAH thermochemolysis, although they are a common feature in terrestrial samples. Along with vacuum pyrolysis results, thermochemolysis shows that nitrogen is probably sequestered in condensed structures like heterocyclic aromatic rings, unlike oxygen, which is mainly located within linkages between aromatic units. This is confirmed by solid state 15N NMR performed on IOM from Orgueil, showing that nitrogen is present in pyrrole, indole, and carbazole moieties. These data show that amino acids are neither derived from the hydrolysis of IOM nor from a common precursor. In order to reconcile the literature isotopic data and the present molecular results, it is proposed that aldehydes and ketones (1) originated during irradiation of ice in space and (2) were then mobilized during the planetesimal hydrothermalism, yielding the formation of amino acids. If correct, prebiotic molecules are the products of the subsurface chemistry of planetesimals and are thus undetectable through astronomical probes.

  7. Origin and variability of particulate matter (PM10 and PM2.5) mass concentrations over an Eastern Mediterranean city

    NASA Astrophysics Data System (ADS)

    Saliba, N. A.; El Jam, F.; El Tayar, G.; Obeid, W.; Roumie, M.

    2010-07-01

    Being a semi-enclosed area, the Eastern Mediterranean region experiences high Particulate Matter (PM) levels that could be attributed to sources originating from the region and from long-range transported pollutants. In this study, a long-term evaluation of PM10 and PM2.5 mass concentrations reveals that averages of PM10 and PM2.5 concentrations collected between 2003 and 2007 in several different sites in Beirut exceeded the World Health Organization (WHO) PM10 and PM2.5 annual averages (20 and 10 µg m - 3 , respectively). When compared to other sites in the region, levels fell in general outside the usual range for most other urban sites that are not directly affected by industrial activity. The average PM2.5/PM10 ratios were about 0.42, a value that is typical of urban sites. The overall averages for different seasons were higher in fall and summer as a result of low precipitations, the increase of dust storm activities in fall and the enhancement of sea and land breezes in summer, along with the increase in traffic activities (summer is a high touristic season). Using the HYSPLIT model for about 500 sampled days in Beirut, Lebanon, it was found that 60% of the wind comes from the N, NW and NE, while the remaining 40% comes from the S, SW and SE. Comparing the sources assigned to the pre- (BH) and post- (HH) 2006-war sites, it was found that aged dust increased by 64% in total PM10 and secondary aerosols by 150% in fine PM in HH over BH. Furthermore, much higher average percentages of sulfates and nitrates were determined in fine PMs in HH, indicating increased levels of their precursors NO x, SO x and Ca generated from a higher density of gasoline, diesel vehicles and construction debris.

  8. Correlated alteration effects in CM carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Browning, Lauren B.; McSween, Harry Y., Jr.; Zolensky, Michael E.

    1996-07-01

    Three parameters are proposed to determine the relative extent of alteration in CM chondrites. The mineralogic alteration index monitors the relative progress of coupled substitutions in the progressive alteration of cronstedtite to Mg-serpentine and increases with increasing alteration. To calculate values of this index, an algorithm has been developed to estimate the average matrix phyllosilicate composition in individual CM chondrites. The second parameter is the volume percent of isolated matrix silicates, which decreases with progressive alteration due to mineral hydration. Finally, the volume percent of chondrule alteration monitors the extent of chondrule phyllosilicate production and increases as alteration proceeds. These parameters define the first CM alteration scale that relies on multiple indicators of progressive alteration. The following relative order of increasing alteration is established by this model: Murchison ≤ Bells < Pollen ≤ Murray < Mighei < Nogoya < Cold Bokkeveld. The relative degree of aqueous processing Cochabamba and Boriskino experienced is less precisely constrained, although both fall near the middle of this sequence. A comparison between the mineralogic alteration index and literature values for the whole-rock chemistry of CM chondrites reveals several correlations. A positive, nearly linear correlation between bulk H content and progressive CM alteration suggests an approximately constant production rate of new phyllosilicates relative to the mineralogical transition from cronstedtite to Mg-serpentine. The abundance of trapped planetary 36Ar decreases systematically in progressively altered CM chondrites, suggesting the wholesale destruction of primary noble gas carrier phase (s) by aqueous reactions. Because low temperature fluid-rock reactions are generally associated with large isotopic mass fractionation factors, we also compared our model predictions with δ18O values for bulk CM samples. Although some of these data are

  9. The lithophile trace elements in enstatite chondrites

    NASA Astrophysics Data System (ADS)

    Barrat, J. A.; Zanda, B.; Jambon, A.; Bollinger, C.

    2014-03-01

    We report on the abundances of a selected set of lithophile trace elements (namely REEs, Y, Rb, Ba, Sr, Zr, Hf, Nb, Th, U) in a comprehensive suite of enstatite chondrites (EC-13 EH and 11 EL). EH3 and EL3 display only minor deviations from chondritic distributions for these elements. In most metamorphosed EC, a wide range of compositions is observed and suggests a mobility of many of the elements studied during the history of these rocks. For example, EL6 chondrites exhibit light-REE and Nb depletions, negative Eu anomalies, and positive Y anomalies. More important trace element fractionations are observed in metamorphosed EH like St Marks (Rb depletion), LAP 02225 (Rb, Nb, Zr, Eu, light REE depletions) and Galim (b), which displays large Ba, Sr, Eu, Nb and light REE depletions. Leaching experiments were undertaken to investigate the contributions of sulfides in the whole rock budgets. These phases control not only the REE budget, but also important fractions of the other elements we studied. These fractions strongly depend on the type of the rock (EH or EL, and metamorphic grade). For many elements, the sulfide contributions increase with the metamorphic grades. The trace element abundances of silicate residues are extremely variable. Negative Sm and Yb anomalies are observed in EL3 and EH3 residues, and are certainly the results of early nebular processes. Such anomalies are lacking in residues obtained with most metamorphosed EC, underlining the importance of trace element redistributions during metamorphism. In addition, EL6 residues display distinctive positive Y anomalies that could be potentially ascribed to a less chalcophile behavior than Ho in the conditions that prevailed during EL metamorphism. EH3 and EL3 display only minor deviations from chondritic distributions for these elements. In most metamorphosed EC, a wide range of compositions is obtained and indicates undeniably a mobility of many of the elements studied during the complex thermal history

  10. Sulfur and Selenium in Chondritic Meteorites

    NASA Astrophysics Data System (ADS)

    Dreibus, G.; Palme, H.; Spettel, B.; Wanke, H.

    1993-07-01

    Selenium is the only truly chalcophile element in chondritic meteorites. It has no other host phases except sulfides. Since Se-volatility is similar to S-volatility one may expect constant S/Se ratios. To test this hypothesis chondritic meteorites were analyzed for Se and S. To avoid problems from inhomogeneous distribution of sulfides the same samples that had been analyzed for Se by INAA were analyzed for S (see Table 1) using a Leybold Heraeus Carbon and Sulfur Analyser (CSA 2002). Solar System Abundances of S and Se: The average S-content of CI- meteorites is with 5.41% in agreement with an earlier average of 5.25% for Orgueil [1], but not with higher S-contents for Ivuna, Alais, and Tonk. Inclusion of these data led to an average CI- content of 6.25% in the Anders and Grevesse compilation [2]. The essentially constant average S/Se ratio in all groups of carbonaceous chondrites of 2563 +- 190 suggests that our Orgueil S-content provides a reliable estimate for the average solar system. The new solar S/Se ratio and the CI-value of Se of 21.3 ppm [3] yield an atomic S/Se ratio of 6200 +- 170, 24% below that calculated from [2]. Weathering Effects: Some of the carbonaceous chondrite finds have similar S/Se ratios as falls (see Table 1). However the badly- weathered Arch (CVR) and Colony (CO) and the two C4-chondrites Mulga West and Maralinga have much lower S and somewhat lower Se contents compared to unweathered meteorites. Their S/Se ratios of 1000-230 indicate higher losses of S--probably by oxidation--as of Se. The low Na-contents in Arch and Colony rel. to CV3 and CO3 may also reflect weathering. Low S/Se ratios in the Sahara meteorites are also indicative of weathering processes. The depletion factors for the CV3- chondrite Acfer086 are, relative to average CV, 10 (S), 5 (Se), 6 (Na), and 4 (Ni). Lower absolute depletions, but the same depletion sequence are found for the CO-meteorite Acfer 202. In the CO/CM Acfer 094 only S and Na are depleted. The

  11. Carbonate abundances and isotopic compositions in chondrites

    NASA Astrophysics Data System (ADS)

    Alexander, C. M. O'd.; Bowden, R.; Fogel, M. L.; Howard, K. T.

    2015-04-01

    We report the bulk C abundances, and C and O isotopic compositions of carbonates in 64 CM chondrites, 14 CR chondrites, 2 CI chondrites, LEW 85332 (C2), Kaba (CV3), and Semarkona (LL3.0). For the unheated CMs, the total ranges of carbonate isotopic compositions are δ13C ≈ 25-75‰ and δ18O ≈ 15-35‰, and bulk carbonate C contents range from 0.03 to 0.60 wt%. There is no simple correlation between carbonate abundance and isotopic composition, or between either of these parameters and the extent of alteration. Unless accretion was very heterogeneous, the uncorrelated variations in extent of alteration and carbonate abundance suggests that there was a period of open system behavior in the CM parent body, probably prior to or at the start of aqueous alteration. Most of the ranges in CM carbonate isotopic compositions can be explained by their formation at different temperatures (0-130 °C) from a single fluid in which the carbonate O isotopes were controlled by equilibrium with water (δ18O ≈ 5‰) and the C isotopes were controlled by equilibrium with CO and/or CH4 (δ13C ≈ -33‰ or -20‰ for CO- or CH4-dominated systems, respectively). However, carbonate formation would have to have been inefficient, otherwise carbonate compositions would have resembled those of the starting fluid. A quite similar fluid composition (δ18O ≈ -5.5‰, and δ13C ≈ -31‰ or -17‰ for CO- or CH4-dominated systems, respectively) can explain the carbonate compositions of the CIs, although the formation temperatures would have been lower (~10-40 °C) and the relative abundances of calcite and dolomite may play a more important role in determining bulk carbonate compositions than in the CMs. The CR carbonates exhibit a similar range of O isotopes, but an almost bimodal distribution of C isotopes between more (δ13C ≈ 65-80‰) and less altered samples (δ13C ≈ 30-40‰). This bimodality can still be explained by precipitation from fluids with the same isotopic

  12. Determining the Origin and Fate of Particulate Plant-Derived Organic Matter in the Rhone River (France) : A Lipid Tracer Review

    NASA Astrophysics Data System (ADS)

    Galeron, M. A.; Amiraux, R.; Charriere, B.; Radakovitch, O.; Raimbault, P.; Garcia, N.; Lagadec, V.; Vaultier, F.; Rontani, J. F.

    2014-12-01

    A number of lipid tracers including fatty acids, hydroxyacids, n-alkanols, sterols and triterpenoids were used to determine the origin and fate of suspended particulate organic matter (POM) collected in the Rhone River (France), with a main focus on phytosterols, such as sitosterol, desmosterol, brassicasterol and cholesterol. This seasonal survey (April 2011 to May 2013) revealed a year-round strong terrigenous contribution to the plant derived particulate organic matter (POM) with significant algal inputs observed in March and attributed to phytoplanktonic blooms likely dominated by diatoms. Specific sitosterol and cholesterol degradation products were quantified and used to estimate the part of biotic and abiotic degradation of POM within the river. Plant-derived organic matter appears to be mainly affected by photo-oxidation and autoxidation (free radical oxidation), while organic matter of human origin, evidenced by the presence of coprostanol, is clearly more prone to bacterial degradation. Despite the involvement of an intense autoxidation inducing homolytic cleavage of peroxy bonds, a significant proportion of hydroperoxides is still intact in higher plant debris. These compounds could play a role in the degradation of terrestrial material by inducing an intense autoxidation upon its arrival at sea. Although sitosterol has been commonly used as a tracer of the terrestrial origin of POM in rivers, we show here that is it also found in phytoplankton, which highlights the need to use different tracers to determine the origin of POM in rivers. As part of the set of tracers we use, we have identified betulin to be an interesting candidate, although limited to a number of angiosperms species. Not only can we trace betulin to an unequivocal terrestrial origin, we also identified its specific degradation products, allowing us to trace the degradation state of angiosperm particulate debris in rivers, as well as the type of degradation undergone.

  13. Petrology and Geochemistry of LEW 88663 and PAT 91501: High Petrologic L Chondrites

    NASA Astrophysics Data System (ADS)

    Mittlefehldt, D. W.; Lindstrom, M. M.; Field, S. W.

    1993-07-01

    (sub)20.7, clinopyroxene Wo(sub)34.3En(sub)52.4Fs(sub)13.3, plagioclase Ab(sub)81.6An(sub)14.0Or(sub)44. Geochemistry: We have completed INM analysis of LEW 88663 only; analyses of PAT 91501 are in progress. The weighted mean lithophile element (refractory, moderately volatile, and volatile) content of LEW 88663 normalized to average L chondrites [1] is 0.97. The weighted mean siderophile element (excluding Fe) content is only 0.57x L. This supports the suggestion that LEW 88663 lost metal relative to average L chondrites, although not as complete as implied earlier [1]. The mean lithophile-element abundance is that of L chondrites, but the lithophile-element pattern is fractionated. Highly incompatible elements are enriched in LEW 88663 relative to L chondrites (e.g., La 2.6x, Sm 1.9x L chondrites), while the more compatible elements are near L chondrite levels or depleted (e.g., Lu 1.1x, Sc 0.94x, Cr 0.87x L chondrites). Discussion: LEW 88663 and PAT 91501 are texturally similar to the Shaw L7 chondrite [3] and to poikilitic textured clasts in LL chondrites [4]. Several textural and mineralogical characteristics of PAT 91501 indicate that this stone is in part igneous. Large rounded troilite +/- metal nodules imply that melting occurred in the metal-troilite system. Interstitial material consists of euhedral, zoned chromites, euhedral clinopyroxene overgrowths on orthopyroxene, and plagioclase + glass. Olivine often shows euhedral faces in contact with the interstitial regions. These textures indicate that the interstitial regions were molten. The average pyroxene compositions in PAT 91501 indicate equilibration at 1200 degrees C [5], above the ordinary chondrite solidus [6]. Although PAT 91501 is in part igneous in origin, we have yet to determine whether it represents an extension of parent body heating from that of metamorphosed L chondrites, or whether it represents impact melting on the parent body. We will evaluate shock features, cooling rates, and the bulk

  14. A strongly hydrated microclast in the Rumuruti chondrite NWA 6828: Implications for the distribution of hydrous material in the solar system

    NASA Astrophysics Data System (ADS)

    Greshake, Ansgar

    2014-05-01

    Hydrous carbonaceous microclasts are by far the most abundant foreign fragments in stony meteorites and mostly resemble CI1-, CM2-, or CR2-like material. Their occurrence is of great importance for understanding the distribution and migration of water-bearing volatile-rich matter in the solar system. This paper reports the first finding of a strongly hydrated microclast in a Rumuruti chondrite. The R3-6 chondrite Northwest Africa 6828 contains a 420 × 325 μm sized angular foreign fragment exhibiting sharp boundaries to the surrounding R-type matrix. The clast is dominantly composed of magnetite, pyrrhotite, rare Ca-carbonate, and very rare Mg-rich olivine set in an abundant fine-grained phyllosilicate-rich matrix. Phyllosilicates are serpentine and saponite. One region of the clast is dominated by forsteritic olivine (Fa<2) supported by a network of interstitial Ca-carbonate. The clast is crosscut by Ca-carbonate-filled veins and lacks any chondrules, calcium-aluminum-rich inclusions, or their respective pseudomorphs. The hydrous clast contains also a single grain of the very rare phosphide andreyivanovite. Comparison with CI1, CM2, and CR2 chondrites as well as with the ungrouped C2 chondrite Tagish Lake shows no positive match with any of these types of meteorites. The clast may, thus, either represent a fragment of an unsampled lithology of the hydrous carbonaceous chondrite parent asteroids or constitute a sample from an as yet unknown parent body, maybe even a comet. Rumuruti chondrites are a unique group of highly oxidized meteorites that probably accreted at a heliocentric distance >1 AU between the formation regions of ordinary and carbonaceous chondrites. The occurrence of a hydrous microclast in an R chondrite attests to the presence of such material also in this region at least at some point in time and documents the wide distribution of water-bearing (possibly zodiacal cloud) material in the solar system.

  15. 146Sm-142Nd systematics measured in enstatite chondrites reveals a heterogeneous distribution of 142Nd in the solar nebula.

    PubMed

    Gannoun, Abdelmouhcine; Boyet, Maud; Rizo, Hanika; El Goresy, Ahmed

    2011-05-10

    The short-lived (146)Sm-(142)Nd chronometer (T(1/2) = 103 Ma) is used to constrain the early silicate evolution of planetary bodies. The composition of bulk terrestrial planets is then considered to be similar to that of primitive chondrites that represent the building blocks of rocky planets. However for many elements chondrites preserve small isotope differences. In this case it is not always clear to what extent these variations reflect the isotope heterogeneity of the protosolar nebula rather than being produced by the decay of parent isotopes. Here we present Sm-Nd isotopes data measured in a comprehensive suite of enstatite chondrites (EC). The EC preserve (142)Nd/(144)Nd ratios that range from those of ordinary chondrites to values similar to terrestrial samples. The EC having terrestrial (142)Nd/(144)Nd ratios are also characterized by small (144)Sm excesses, which is a pure p-process nuclide. The correlation between (144)Sm and (142)Nd for chondrites may indicate a heterogeneous distribution in the solar nebula of p-process matter synthesized in supernovae. However to explain the difference in (142)Nd/(144)Nd ratios, 20% of the p-process contribution to (142)Nd is required, at odds with the value of 4% currently proposed in stellar models. This study highlights the necessity of obtaining high-precision (144)Sm measurements to interpret properly measured (142)Nd signatures. Another explanation could be that the chondrites sample material formed in different pulses of the lifetime of asymptotic giant branch stars. Then the isotope signature measured in SiC presolar would not represent the unique s-process signature of the material present in the solar nebula during accretion. PMID:21515828

  16. 146Sm–142Nd systematics measured in enstatite chondrites reveals a heterogeneous distribution of 142Nd in the solar nebula

    PubMed Central

    Gannoun, Abdelmouhcine; Boyet, Maud; Rizo, Hanika; El Goresy, Ahmed

    2011-01-01

    The short-lived 146Sm–142Nd chronometer (T1/2 = 103 Ma) is used to constrain the early silicate evolution of planetary bodies. The composition of bulk terrestrial planets is then considered to be similar to that of primitive chondrites that represent the building blocks of rocky planets. However for many elements chondrites preserve small isotope differences. In this case it is not always clear to what extent these variations reflect the isotope heterogeneity of the protosolar nebula rather than being produced by the decay of parent isotopes. Here we present Sm–Nd isotopes data measured in a comprehensive suite of enstatite chondrites (EC). The EC preserve 142Nd/144Nd ratios that range from those of ordinary chondrites to values similar to terrestrial samples. The EC having terrestrial 142Nd/144Nd ratios are also characterized by small 144Sm excesses, which is a pure p-process nuclide. The correlation between 144Sm and 142Nd for chondrites may indicate a heterogeneous distribution in the solar nebula of p-process matter synthesized in supernovae. However to explain the difference in 142Nd/144Nd ratios, 20% of the p-process contribution to 142Nd is required, at odds with the value of 4% currently proposed in stellar models. This study highlights the necessity of obtaining high-precision 144Sm measurements to interpret properly measured 142Nd signatures. Another explanation could be that the chondrites sample material formed in different pulses of the lifetime of asymptotic giant branch stars. Then the isotope signature measured in SiC presolar would not represent the unique s-process signature of the material present in the solar nebula during accretion. PMID:21515828

  17. Formation of chondrites in a thick dynamic regolith

    NASA Astrophysics Data System (ADS)

    Huang, S.; Sears, D. W. G.; Benoit, P. H.

    1994-07-01

    H was proposed that chondrules formed as the products of energetic impacts in a very thick dynamic dust layer of an accreting asteroid-sized object and that the various chondrule groups, and thus chondrite classes, formed by variations in the number and intensity of impacts. We here argue that in such a dust layer there was probably a steady flow of volatiles and that on occasion conditions may have resembled those of a fluidized bed in which density and size sorting produced the metal-silicate fractionation and chondrule size distributions observed among the chondrites. The existence of a temporary atmosphere is suggested by the elemental and isotopic abundance patterns observed in chondrules. The atmosphere may have been permanent, but was probably transient, consisting of water and other volatiles from the parent body most probably produced during accretion and chondrule formation. It seems unlikely that such an atmosphere would be cosmic in composition and there are experimental reasons for suspecting that the H/O ratio was many orders of magnitude below cosmic and the P(Na) was much higher than expected for gases of cosmic composition. The requirements for minimal fluidization are determined by equating the upward drag force of the escaping volatiles and the downward gravitational force on the particles. We calculate that most asteroids smaller than few hundred kilometers should be capable of producing a sufficiently high flow rate of volatiles to produce fluidization. The extent of presumed fluidization seems to decrease with present volatile contents of the classes, consistent with the loss of volatiles during fluidization from parents of generally similar original composition.

  18. More evidence for a partially differentiated CV chondrite parent body from paleomagnetic studies of ALH 84028 and ALH 85006

    NASA Astrophysics Data System (ADS)

    Klein, B. Z.; Weiss, B. P.; Carporzen, L.

    2014-12-01

    Recent paleomagnetic studies of the CV carbonaceous chondrites Allende and Kaba and numerical modeling studies have suggested that the CV chondrite parent body may have been partially differentiated, with a molten metallic core, dynamo magnetic field, and an unmelted chondritic lid. To further evaluate this hypothesis, here we present new paleomagnetic analyses of two previously unstudied CV3 chondrites: the unshocked, Allende-type oxidized chondrite ALH 84028 and the weakly shocked, Bali-type oxidized chondrite ALH 85006. We preformed alternating field (AF) and thermal demagnetization experiments, AF-based paleointensity experiments, and rock magnetic experiments on mutually oriented subsamples of each meteorite. Both meteorites pass fusion crust baked contact tests, indicating that their interiors retain a magnetization predating atmospheric entry. In the interior of ALH 84028, we identified a unidirectional medium temperature (blocked to 300°C), high coercivity (blocked to >420 mT) component. In the interior of ALH 85006, we identified MT components blocked up to 400-475°C. The unblocking temperatures and unidirectional nature of the MT components in both meteorites indicates their origin as a partial thermoremanence or thermochemical remanence acquired during metamorphism following accretion of the CV chondrite parent body. Our paleointensity experiments indicate paleofield intensities of 32-73 μT for ALH 84028 and 14-45 μT for ALH 85006 . When combined with similar recent results for Allende and Kaba, there is now consistent evidence for dynamo fields from four CV chondrites with collectively diverse lithologies and shock states. Therefore, the magnetic field on the CV parent body was not a localized event like that expected for a field generated by meteoroid impact plasmas and instead likely had a wide spatial extent. Further, given the younger I-Xe ages for Kaba compared to Allende (9-10 Ma and 2-3 Ma after Stillwater respectively), CV parent body

  19. Petrology and Cosmochemistry of a Suite of R Chondrites

    NASA Technical Reports Server (NTRS)

    Torrano, Z. A.; Mittlefehldt, D. W.; Peng, Z. X.

    2015-01-01

    Chondrites are among the most primitive surviving materials from the early solar system. They are divided into groups based on chemical types defined by mineralogy, bulk composition, and oxygen isotope compositions. Chondrites range in petrographic grade from type 1 to type 7. Type 3 chondrites are the most primitive and are little changed from the nebular solids accreted to form asteroids. They are composed of chondrules, fine-grained matrix, metal and sulfide, plus or minus Ca-Al-rich inclusions. With increasing aqueous alteration at low temperatures, members of some chondrite classes transformed from type 3 towards type 1. With increasing thermal metamorphism and low fluid content, members of other classes changed from type 3 towards type 7. Rumuruti (R) chondrites are a rare group (0.1% of falls) similar to ordinary chondrites in some properties but different in others. They are characterized by low chondrule/matrix modal abundance ratios, high oxidation state, small mean chondrule size, abundant sulfides and low metal contents. R chondrites vary in petrologic type from 3 to 6. They are important objects to study because some of them have undergone metamorphism at high temperatures in the presence of aqueous fluids. In contrast, CM and CI chondrites were heated to low temperatures in the presence of aqueous fluids leading to alteration; they contain low-T hydrous phases (phyllosilicates) and little or no remaining metal. Ordinary chondrites were heated to high temperatures in a low-fluid environment resulting in anhydrous metamorphic rocks. R6 chondrites are highly metamorphosed and some contain the high-T hydrous phases mica and amphibole. R chondrites are thus unique and give us an opportunity to examine whether there are compositional effects caused by high-T, highfluid metamorphism of nebular materials.

  20. Mineral Associations and Character of Isotopically Anomalous Organic Material in the Tagish Lake Carbonaceous Chondrite

    SciTech Connect

    Zega, T.; Alexander, C; Busemann, H; Nittler, L; Hoppe, P; Stroud, R; Young, A

    2010-01-01

    We report a coordinated analytical study of matrix material in the Tagish Lake carbonaceous chondrite in which the same small ({le}20 {micro}m) fragments were measured by secondary ion mass spectrometry (SIMS), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), electron energy-loss spectroscopy (EELS), and X-ray absorption near-edge spectroscopy (XANES). SIMS analysis reveals H and N isotopic anomalies (hotspots), ranging from hundreds to thousands of nanometers in size, which are present throughout the fragments. Although the differences in spatial resolution of the SIMS techniques we have used introduce some uncertainty into the exact location of the hotspots, in general, the H and N isotopic anomalies are spatially correlated with C enrichments, suggesting an organic carrier. TEM analysis, enabled by site-specific extraction using a focused-ion-beam scanning-electron microscope, shows that the hotspots contain an amorphous component, Fe-Ni sulfides, serpentine, and mixed-cation carbonates. TEM imaging reveals that the amorphous component occurs in solid and porous forms, EDS indicates that it contains abundant C, and EELS and XANES at the C K edge reveal that it is largely aromatic. This amorphous component is probably macromolecular C, likely the carrier of the isotopic anomalies, and similar to the material extracted from bulk samples as insoluble organic matter. However, given the large sizes of some of the hotspots, the disparity in spatial resolution among the various techniques employed in our study, and the phases with which they are associated, we cannot entirely rule out that some of the isotopic anomalies are carried by inorganic material, e.g., sheet silicates. The isotopic composition of the organic matter points to an initially primitive origin, quite possibly within cold interstellar clouds or the outer reaches of the solar protoplanetary disk. The association of organic material with secondary phases, e

  1. Compositions of Partly Altered Olivine and Replacement Serpentine in the CM2 Chondrite QUE93005

    NASA Technical Reports Server (NTRS)

    Velbel, M. A.; Tonui, E. K.; Zolensky, M. E.

    2005-01-01

    Some phyllosilicates in CM carbonaceous chondrites formed by aqueous alteration of anhydrous precursor phases. Although broad trends in the compositions of hydrous phyllosilicates are recognized and believed to be related to trends in degree of aqueous alteration, details of the reactions that formed specific secondary minerals remain obscure. This paper reports compositional relationships between remnants of partially pseudomorphically (or alteromorphically) replaced silicates and their alteration products (serpentine) in the CM2 chondrite QUE93005 and compares it with previously published results for ALH81002. Reactants and products were characterized by optical petrography, backscattered scanning electron microscopy (BSEM), and electron microprobe. By focusing on serpentine formed from known reactants (olivines), and on only those instances in which some of the reactant silicate remains, direct compositional relationships between reactants and products, and the elemental mobility required by the reactions, can be established. Additional information is included in the original extended abstract.

  2. Phosphate-sulfide assemblages and Al/Ca ratios in type-3 chondrites

    NASA Technical Reports Server (NTRS)

    Rubin, A. E.; Grossman, J. N.

    1985-01-01

    Electron microscopic examinations were carried out on various chondrites to re-examine previously reported anomalously high Al/Ca ratios. Polished thin sections of the three CV3, two CO3 and the Krymka LL3 chondrites were scanned to characterize the phosphate-sulfide inclusions. The formation of the assemblages was interpreted as proceeding in five steps, starting with the formation of metal grains with early nebular material and finishing with a reaction between schreibersite with Ca, O and Cl to form merrillite and chloropatite. The abundances of the observed assemblages were not high enough to imply Al/Ca ratios similar to whole-rocks. It is concluded that the specimens were originally examined with a broader electron beam than used to examine standard samples, and resulted in the anomalously high Al/Ca ratios.

  3. Origins of suspended particulate matter based on sterol distribution in low salinity water mass observed in the offshore East China Sea.

    PubMed

    Kim, Moonkoo; Jung, Jee-Hyun; Jin, Yongnu; Han, Gi Myeong; Lee, Taehee; Hong, Sang Hee; Yim, Un Hyuk; Shim, Won Joon; Choi, Dong-Lim; Kannan, Narayanan

    2016-07-15

    The molecular composition and distribution of sterols were investigated in the East China Sea to identify the origins of suspended particulate matter (SPM) in offshore waters influenced by Changjiang River Diluted Water (CRDW). Total sterol concentrations ranged from 3200 to 31,900pgL(-1) and 663 to 5690pgL(-1) in the particulate and dissolved phases, respectively. Marine sterols dominated representing 71% and 66% in the particulate and dissolved phases, respectively. Typical sewage markers, such as coprostanol, were usually absent at ~250km offshore. However, sterols from allochthonous terrestrial plants were still detected at these sites. A negative relationship was observed between salinity and concentrations of terrestrial sterols in SPM, suggesting that significant amounts of terrestrial particulate matter traveled long distance offshore in the East China Sea, and the Changjiang River Diluted Water (CRDW) was an effective carrier of land-derived particulate organic matter to the offshore East China Sea. PMID:27167134

  4. N-15-Rich Organic Globules in a Cluster IDP and the Bells CM2 Chondrite

    NASA Technical Reports Server (NTRS)

    Messenger, S.; Nakamura-Messenger, K.; Keller, Lindsay P.

    2008-01-01

    Organic matter in primitive meteorites and chondritic porous interplanetary dust particles (CP IDPs) is commonly enriched in D/H and 15N/14N relative to terrestrial values [1-3]. These anomalies are ascribed to the partial preservation of presolar cold molecular cloud material [1]. Some meteorites and IDPs contain m-size inclusions with extreme H and N isotopic anomalies [2-4], possibly due to preserved pristine primordial organic grains. We recently showed that the in the Tagish Lake meteorite, the principle carriers of these anomalies are sub- m, hollow organic globules [5]. The globules likely formed by photochemical processing of organic ices in a cold molecular cloud or the outermost regions of the protosolar disk [5]. We proposed that similar materials should be common among primitive meteorites, IDPs, and comets. Similar objects have been observed in organic extracts of carbonaceous chondrites [6-8], however their N and H isotopic compositions are generally unknown. Bulk H and N isotopic compositions may indicate which meteorites best preserve interstellar organic compounds. Thus, we selected the Bells CM2 carbonaceous chondrites for study based on its large bulk 15N (+335 %) and D (+990 %) [9].

  5. Dark matter or point sources? Utilizing the 1-pt PDF to understand the origin of the GeV excess seen by the Fermi LAT detector

    NASA Astrophysics Data System (ADS)

    Harrison, Natalie; Gaskins, Jennifer; Fermi LAT Collaboration

    2015-04-01

    An excess of gamma rays from the Inner Galaxy in the Fermi LAT data has been identified. This emission has been interpreted as a possible signature of the annihilation of dark matter particles, or as originating from a collection of unresolved point sources, such as gamma-ray millisecond pulsars. We explore the clustering properties of the diffuse emission arising from a population of gamma-ray point sources and from the annihilation of dark matter particles in the halo of the Galaxy using the 1-pt probability distribution function of counts in pixels (1pt-PDF, the number of pixels with a specified number of counts as a function of counts); this approach is also known as fluctuation analysis or P(D) analysis. We analyze the 1-pt PDF of the GeV excess within a +/- 5 degree box around the Galactic Center. For both dark matter and point sources we adopt the spatial distribution and spectrum to fit the GeV excess. We determine the contributions to the 1-pt PDF from the Galactic diffuse and isotropic diffuse emissions, dark matter, and point sources, and discuss the implications of this analysis for the origin of the GeV excess.

  6. Dark matter or point sources? Utilizing the 1-pt PDF to understand the origin of the GeV excess seen by the Fermi LAT detector

    NASA Astrophysics Data System (ADS)

    Harrison, Natalie; Siegal-Gaskins, Jennifer M.

    2015-01-01

    An excess of gamma rays from the Inner Galaxy in the Fermi LAT data has been identified. This emission has been interpreted as a possible signature of the annihilation of dark matter particles, or as originating from a collection of unresolved point sources, such as gamma-ray millisecond pulsars. We explore the clustering properties of the diffuse emission arising from a population of gamma-ray point sources and from the annihilation of dark matter particles in the halo of the Galaxy using the 1-pt probability distribution function of counts in pixels (1pt-PDF, the number of pixels with a specified number of counts as a function of counts); this approach is also known as fluctuation analysis or P(D) analysis. We analyze the 1-pt PDF of the GeV excess within a +/- 5 degree box around the Galactic Center. For both dark matter and point sources we adopt the spatial distribution and spectrum to fit the GeV excess. We determine the contributions to the 1-pt PDF from the Galactic diffuse and isotropic diffuse emission, dark matter, and point sources, and discuss the implications of this analysis for the origin of the GeV excess.

  7. Origin, distribution and alteration of organic matter and generation and migration of hydrocarbons in Austin Chalk, Upper Cretaceous, southeastern Texas. Final report, September 1, 1980-August 31, 1981

    SciTech Connect

    Grabowski, G.J. Jr.

    1981-01-01

    The kerogen and bitumen from samples of the Austin Chalk from the subsurface of southeastern Texas were analyzed to determine the origin of the organic matter and the alteration of the kerogen to form petroleum. The effects of mineral composition on the rate of alteration and on the composition of hydrocarbons generated was examined. The source-rock potential and the processes of migration and reservoiring in the chalk are considered.

  8. Characteristics and origin of organic matter and basal respiration of soils from Majella massif (Central Apennines, Italy)

    NASA Astrophysics Data System (ADS)

    Basili, M.; Cioci, C.; Cocco, S.; Agnelli, A.; di Peco, D.; Ferraris, P.; Corti, G.

    2009-04-01

    The effects of the global climate change on the soil organic matter (SOM) are still open to debate. Many studies hypothesize an increase of the CO2 fluxes from the soil following the rise of air temperature, especially for the high latitude soils where the low temperatures have a protective effect on the SOM, holding the mineralization reactions back. We studied the feedback between soil and climate change in the Mediterranean environments, on patterned ground soils and soils developed from glacial lacustrine sediments found in the high-elevated areas (2500 m a.s.l.) of Majella massif (Central Apennines, Italy). Here, several profiles were opened and the soil described and sampled according to the recognized horizons. The samples were characterised according to the routine analyses and the SOM extracted according to the International Humic Substances Society protocol. The obtained humic and fulvic acids were characterised for elemental composition and by Fourier-transform infrared (FT-IR) spectroscopy. Further, the basal respiration at 5°C, 20°C and 30°C for 20 days was determined on the samples collected from the superficial horizon of each soil. The extracted humic substances showed a particular composition, being mostly comprised of proteinaceous residues (amides II and III), polysaccarides, and esters and aliphatic compounds. This unusual chemical structure and the paucity of vegetation in the study area could support the hypothesis of a mainly soil animal origin of the SOM, probably due to residues of insects, arachnids and arthropods. In fact, the species belonging to these Orders are abundant in these ecosystems and, further, are often characterised by the presence of compounds, such as glycerine and glycoproteins, in their organic fluids that act as antifreezing systems. The basal respiration experiments indicated that the soil microbial community was active at 5°C, while at 20°C or 30°C rather no respiration occurred; further, after 20 days at both

  9. Fe-Ni metal in primitive chondrites: Indicators of classification and metamorphic conditions for ordinary and CO chondrites

    USGS Publications Warehouse

    Kimura, M.; Grossman, J.N.; Weisberg, M.K.

    2008-01-01

    We report the results of our petrological and mineralogical study of Fe-Ni metal in type 3 ordinary and CO chondrites, and the ungrouped carbonaceous chondrite Acfer 094. Fe-Ni metal in ordinary and CO chondrites occurs in chondrule interiors, on chondrule surfaces, and as isolated grains in the matrix. Isolated Ni-rich metal in chondrites of petrologic type lower than type 3.10 is enriched in Co relative to the kamacite in chondrules. However, Ni-rich metal in type 3.15-3.9 chondrites always contains less Co than does kamacite. Fe-Ni metal grains in chondrules in Semarkona typically show plessitic intergrowths consisting of submicrometer kamacite and Ni-rich regions. Metal in other type 3 chondrites is composed of fine- to coarse-grained aggregates of kamacite and Ni-rich metal, resulting from metamorphism in the parent body. We found that the number density of Ni-rich grains in metal (number of Ni-rich grains per unit area of metal) in chondrules systematically decreases with increasing petrologic type. Thus, Fe-Ni metal is a highly sensitive recorder of metamorphism in ordinary and carbonaceous chondrites, and can be used to distinguish petrologic type and identify the least thermally metamorphosed chondrites. Among the known ordinary and CO chondrites, Semarkona is the most primitive. The range of metamorphic temperatures were similar for type 3 ordinary and CO chondrites, despite them having different parent bodies. Most Fe-Ni metal in Acfer 094 is martensite, and it preserves primary features. The degree of metamorphism is lower in Acfer 094, a true type 3.00 chondrite, than in Semarkona, which should be reclassified as type 3.01. ?? The Meteoritical Society, 2008.

  10. Extraterrestrial organic matter: a review.

    PubMed

    Irvine, W M

    1998-10-01

    We review the nature of the widespread organic material present in the Milky Way Galaxy and in the Solar System. Attention is given to the links between these environments and between primitive Solar System objects and the early Earth, indicating the preservation of organic material as an interstellar cloud collapsed to form the Solar System and as the Earth accreted such material from asteroids, comets and interplanetary dust particles. In the interstellar medium of the Milky Way Galaxy more than 100 molecular species, the bulk of them organic, have been securely identified, primarily through spectroscopy at the highest radio frequencies. There is considerable evidence for significantly heavier organic molecules, particularly polycyclic aromatics, although precise identification of individual species has not yet been obtained. The so-called diffuse interstellar bands are probably important in this context. The low temperature kinetics in interstellar clouds leads to very large isotopic fractionation, particularly for hydrogen, and this signature is present in organic components preserved in carbonaceous chondritic meteorites. Outer belt asteroids are the probable parent bodies of the carbonaceous chondrites, which may contain as much as 5% organic material, including a rich variety of amino acids, purines, pyrimidines, and other species of potential prebiotic interest. Richer in volatiles and hence less thermally processed are the comets, whose organic matter is abundant and poorly characterized. Cometary volatiles, observed after sublimation into the coma, include many species also present in the interstellar medium. There is evidence that most of the Earth's volatiles may have been supplied by a 'late' bombardment of comets and carbonaceous meteorites, scattered into the inner Solar System following the formation of the giant planets. How much in the way of intact organic molecules of potential prebiotic interest survived delivery to the Earth has become an

  11. Extraterrestrial organic matter: a review

    NASA Technical Reports Server (NTRS)

    Irvine, W. M.

    1998-01-01

    We review the nature of the widespread organic material present in the Milky Way Galaxy and in the Solar System. Attention is given to the links between these environments and between primitive Solar System objects and the early Earth, indicating the preservation of organic material as an interstellar cloud collapsed to form the Solar System and as the Earth accreted such material from asteroids, comets and interplanetary dust particles. In the interstellar medium of the Milky Way Galaxy more than 100 molecular species, the bulk of them organic, have been securely identified, primarily through spectroscopy at the highest radio frequencies. There is considerable evidence for significantly heavier organic molecules, particularly polycyclic aromatics, although precise identification of individual species has not yet been obtained. The so-called diffuse interstellar bands are probably important in this context. The low temperature kinetics in interstellar clouds leads to very large isotopic fractionation, particularly for hydrogen, and this signature is present in organic components preserved in carbonaceous chondritic meteorites. Outer belt asteroids are the probable parent bodies of the carbonaceous chondrites, which may contain as much as 5% organic material, including a rich variety of amino acids, purines, pyrimidines, and other species of potential prebiotic interest. Richer in volatiles and hence less thermally processed are the comets, whose organic matter is abundant and poorly characterized. Cometary volatiles, observed after sublimation into the coma, include many species also present in the interstellar medium. There is evidence that most of the Earth's volatiles may have been supplied by a 'late' bombardment of comets and carbonaceous meteorites, scattered into the inner Solar System following the formation of the giant planets. How much in the way of intact organic molecules of potential prebiotic interest survived delivery to the Earth has become an

  12. Origin distribution and alteration of organic matter and generation and migration of hydrocarbons in Austin Chalk, Upper Cretaceous, Southeastern Texas

    NASA Astrophysics Data System (ADS)

    Grabowski, G. J., Jr.

    1981-08-01

    The Austin Chalk is an impure onshore chalk that was deposited on a ramp marginal to the Gulf of Mexico during the Late Cretaceous. Basinal chalks are organic rich, commonly containing 0.5-5.0% amorphous, sapropelic kerogen derived from marine organic matter with only trace amounts of terrestial kerogen. Less organic matter was deposited and perserved in oxygenated shallow water, and fresh-water diagenesis oxidized the organic matter on outcrop. In each sample, the kerogen is concentrated in microstylolites, with organic fluids segregated in micropores in the chalk.

  13. Fall, recovery, and characterization of the Novato L6 chondrite breccia

    NASA Astrophysics Data System (ADS)

    Jenniskens, Peter; Rubin, Alan E.; Yin, Qing-Zhu; Sears, Derek W. G.; Sandford, Scott A.; Zolensky, Michael E.; Krot, Alexander N.; Blair, Leigh; Kane, Darci; Utas, Jason; Verish, Robert; Friedrich, Jon M.; Wimpenny, Josh; Eppich, Gary R.; Ziegler, Karen; Verosub, Kenneth L.; Rowland, Douglas J.; Albers, Jim; Gural, Peter S.; Grigsby, Bryant; Fries, Marc D.; Matson, Robert; Johnston, Malcolm; Silber, Elizabeth; Brown, Peter; Yamakawa, Akane; Sanborn, Matthew E.; Laubenstein, Matthias; Welten, Kees C.; Nishiizumi, Kunihiko; Meier, Matthias M. M.; Busemann, Henner; Clay, Patricia; Caffee, Marc W.; Schmitt-Kopplin, Phillipe; Hertkorn, Norbert; Glavin, Daniel P.; Callahan, Michael P.; Dworkin, Jason P.; Wu, Qinghao; Zare, Richard N.; Grady, Monica; Verchovsky, Sasha; Emel'Yanenko, Vacheslav; Naroenkov, Sergey; Clark, David L.; Girten, Beverly; Worden, Peter S.

    2014-08-01

    The Novato L6 chondrite fragmental breccia fell in California on 17 October 2012, and was recovered after the Cameras for Allsky Meteor Surveillance (CAMS) project determined the meteor's trajectory between 95 and 46 km altitude. The final fragmentation from 42 to 22 km altitude was exceptionally well documented by digital photographs. The first sample was recovered before rain hit the area. First results from a consortium study of the meteorite's characterization, cosmogenic and radiogenic nuclides, origin, and conditions of the fall are presented. Some meteorites did not retain fusion crust and show evidence of spallation. Before entry, the meteoroid was 35 ± 5 cm in diameter (mass 80 ± 35 kg) with a cosmic-ray exposure age of 9 ± 1 Ma, if it had a one-stage exposure history. A two-stage exposure history is more likely, with lower shielding in the last few Ma. Thermoluminescence data suggest a collision event within the last ˜0.1 Ma. Novato probably belonged to the class of shocked L chondrites that have a common shock age of 470 Ma, based on the U,Th-He age of 420 ± 220 Ma. The measured orbits of Novato, Jesenice, and Innisfree are consistent with a proposed origin of these shocked L chondrites in the Gefion asteroid family, perhaps directly via the 5:2 mean-motion resonance with Jupiter. Novato experienced a stronger compaction than did other L6 chondrites of shock-stage S4. Despite this, a freshly broken surface shows a wide range of organic compounds.

  14. The primitive matrix components of the unique carbonaceous chondrite Acfer 094: a TEM study.

    PubMed

    Greshake, A

    1997-01-01

    The mineralogical and chemical characteristics of the fine-grained matrix (< or = 3 micrometers) of the unique primitive carbonaceous chondrite Acfer 094 have been investigated in detail by scanning electron microscopy (SEM) and analytical transmission electron microscopy (ATEM). Generally, the fine-grained matrix represents a highly unequilibrated assemblage of an amorphous material, small forsteritic olivines (200-300 nm), low Ca-pyroxenes (300-400 nm), and Fe,Ni-sulfides (100-300 nm). The matrix is basically unaffected by secondary processes. Only minor amounts of serpentine and ferrihydrite, as products of hydrous alteration, are present. Texturally, the amorphous material acts as a groundmass to olivines, pyroxenes, and sulfides, mostly exhibiting rounded or elongated morphologies. Only very few clastic mineral grains have been found. The texture and chemical composition of the amorphous material are consistent with an origin by disequilibrium condensation in either the cooling solar nebula or a circumstellar environment. As such, the amorphous material may be considered as a possible precursor of matrix materials in other types of chondrites. The non-clastic matrix olivines (Fo98-99) and pyroxenes (En97-100) are suggested to have formed either by condensation in the solar nebula under highly oxidizing conditions or by recrystallization from the amorphous material. The formation of these grains by fragmentation of chondrule components is unlikely due to chemical and microstructural reasons. Rapid cooling caused the observed intergrowths of clino/orthoenstatite in the Mg-rich matrix pyroxenes. Although some similarities exist comparing the fine-grained matrix of Acfer 094 with the matrices of the unequilibrated CO3 chondrite ALHA77307 and the unique type 3 chondrite Kakangari, Acfer 094 remains unique. Since it contains the highest measured concentrations of circumstellar SiC and the second highest of diamond (highest is Orgueil), it seems reasonable to

  15. L7 chondrites in FRO 90 Antarctic meteorite collection: A discussion

    NASA Astrophysics Data System (ADS)

    Levi, F. A.; Levi-Donati, G. R.

    1994-07-01

    A major problem in stony meteorite research appears to still be unsolved. A clear identification of a petrologic transition from chondritic to achondritic material is not yet obtained. The texture of the Shaw chondrite was for several years of peculiar interest. Being classified as an L7 chondrite, it looked to be not just rare but unique. It is now possible to extend the study to recently recovered material. The examination of the U.S. Antarctic Meteorite Collection, which contains the characterization of 5537 specimens, reveals two samples ascribable to the L7 group. They are LEW 88663, a stone of 14.5 g, severely weathered and PAT 91501, a mass of 8550.6 g, showing moderate weathering. The Frontier Mountain Expedition (FRO), organized by EUROMET, between 1990 December and 1991 January, recovered 256 samples, of which 6 were terrestrial rocks and 250 meteorite specimens. At least 12 of them are L7 chondrites. However, it should be considered that this is the first time that such a high number of L7 samples have been found in a single location. Moreover, the existence of unusual features, symptoms of shock metamorphism, undoubtedly supports the hypothesis of a common origin and/or a common history. They are among others: presence in several samples of the FRO-collection of maskelynite, a diaplectic glass of plagioclasic origin, frequent 'mosaicism' in olivine crystals; and extensive appearance of planar features. We may then confirm that it is desirable that an accurate comparison of the samples be performed, using all possible research methods, hoping in this way to contribute to the solution of the problem.

  16. Fall, Recovery, and Characterization of the Novato L6 Chondrite Breccia

    NASA Technical Reports Server (NTRS)

    Jenniskens, Peter; Rubin, Alan E.; Yin, Qing Zhu; Sears, Derek W. G.; Sandford, Scott A.; Zolensky, Michael E.; Krot, Alexander N.; Blair, Leigh; Kane, Daci; Utas, Jason; Verish, Robert; Friedrich, Jon M.; Wimpenny, Josh; Eppich, Gary R.; Ziegler, Karen; Glavin, Daniel P.; Callahan, Michael P.; Dworkin, Jason P.; Girten, Beverly; Worden, Peter S.

    2014-01-01

    The Novato L6 chondrite fragmental breccia fell in California on 17 October 2012, and was recovered after the Cameras for Allsky Meteor Surveillance (CAMS) project determined the meteor's trajectory between 95 and 46 km altitude. The final fragmentation from 42 to 22 km altitude was exceptionally well documented by digital photographs. The first sample was recovered before rain hit the area. First results from a consortium study of the meteorite's characterization, cosmogenic and radiogenic nuclides, origin, and conditions of the fall are presented. Some meteorites did not retain fusion crust and show evidence of spallation. Before entry, the meteoroid was 35+/-5 cm in diameter (mass 80+/-35 kg) with a cosmic-ray exposure age of 9+/-1 Ma, if it had a one-stage exposure history. A two-stage exposure history is more likely, with lower shielding in the last few Ma. Thermoluminescence data suggest a collision event within the last approx.0.1 Ma. Novato probably belonged to the class of shocked L chondrites that have a common shock age of 470 Ma, based on the U, Th-He age of 420+/-220 Ma. The measured orbits of Novato, Jesenice, and Innisfree are consistent with a proposed origin of these shocked L chondrites in the Gefion asteroid family, perhaps directly via the 5:2 mean-motion resonance with Jupiter. Novato experienced a stronger compaction than did other L6 chondrites of shockstage S4. Despite this, a freshly broken surface shows a wide range of organic compounds.

  17. Fall, Recovery and Characterization of the Novato L6 Chondrite Breccia

    NASA Technical Reports Server (NTRS)

    Jenniskens, Petrus; Rubin, Alan E; Yin, Qing-Zhu; Sears, Derek; Sandford, Scott A.; Zolensky, Michael E.; Krot, Alexander N.; Blair, Leigh; Kane, Darci; Utas, Jason; Versih, Robert; Friedrich, Jon M.; Wimpenny, Josh; Eppich, Gary R.; Ziegler, Karen; Verosub, Kenneth L.; Rowland, Douglas J.; Albers, Jim; Fries, Marc D.; Matson, Robert; Glavin, Daniel P.; Callahan, Michael; Dworkin, Jason P.; Girten, Beverly; Worden, Peter S.

    2013-01-01

    The Novato L6 chondrite fragmental breccia fell in California on 17 October 2012, and was recovered after the Cameras for Allsky Meteor Surveillance (CAMS) project determined the meteor's trajectory between 95 and 45 km altitude. The final fragmentation at 33 1 km altitude was exceptionally well documented by digital photographs. The first sample was recovered before rain hit the area. First results from a consortium study of the meteorite's characterization, cosmogenic and radiogenic nuclides, origin and conditions of the fall are presented. Some meteorites did not retain fusion crust and show evidence of spallation. Before entry, the meteoroid was 35+/-5 cm in diameter (mass 80+/-35 kg) with a cosmic ray exposure age of 9+/-1 Ma, if it had a one-stage exposure history. However, based on the cosmogenic nuclide inventory, a two-stage exposure history is more likely, with lower shielding in the last few Ma. Thermoluminescence data suggest a collision event within the last approx. 0.1 Ma. Novato likely belonged to the class of shocked L chondrites that have a common shock age of 470 Ma, based on the U,Th-He age of 460+/-220 Ma. The measured orbits of Novato, Jesenice and Innisfree are consistent with a proposed origin of these shocked L chondrites in the Gefion asteroid family, but leave open the possibility that they came to us directly from the 5:2 mean motion resonance with Jupiter. Novato experienced a stronger compaction than did other L6 chondrites of shock-stage S4. Despite this, a freshly broken surface shows a wide range of organic compounds.

  18. Magnesium Isotopic Composition of CAIs and Chondrules from CBb Chondrites

    NASA Astrophysics Data System (ADS)

    Gounelle, M.; Young, E. D.; Shahar, A.; Kearsley, A.

    2006-03-01

    We measured magnesium isotope ratios in 17 chondrules and 3 CAIs from the CBb chondrites HH 237 and QUE 94411 by LA-MC-ICPMS. We find no detectable 26Al excesses in the three CAIs and approximately normal (chondritic) d25Mg in CAIs and chondrules.

  19. Terrestrial microbes in martian and chondritic meteorites

    NASA Astrophysics Data System (ADS)

    Airieau, S.; Piceno, Y.; Andersen, G.

    2007-08-01

    Good extraterrestrial analogs for microbiology are SNC meteorites as Mars analogs, and chondrites as early planet analogs. Chondrites and SNCs are used to trace processes in the early solar system and on Mars. Yet, questions about terrestrial contamination and its effects on the isotopic, chemical and mineral characteristics often arise. A wide biodiversity was found in 21 chondrites of groups CR, CV, CK, CO from ANSMET, CI and CM Falls, and 8 SNCs. Studies documented the alteration of meteorites by weathering and biology [1]-[6], and during aqueous extraction for oxygen isotopic analysis [7], visible biofilms grew in the meteorite solutions in days. To assess biological isotopic and chemical impacts, cultures were incubated 11 months and analyzed by PCR. The sequences for 2 isolates from EET 87770 and Leoville were of a good quality with long sequence reads. In EET 87770, the closest matches were in the genus Microbacterium. Soil and plant isolates were close relatives by sequence comparison. Bacillus, a common soil bacterial genus, grew in a Leoville culture. All SNCs exhibited biological activity measured independently by LAL but only 1 colony was successfully cultured from grains of the SNC Los Angeles. Isotopic analyses of samples with various amounts of microbial contamination could help quantified isotopic impact of microbes on protoplanetary chemistry in these rocks. References: [1] Gounelle, M.& Zolensky M. (2001) LPS XXXII, Abstract #999. [2] Fries, M. et al. (2005) Meteoritical Society Meeting 68, Abstract # 5201. [3] Burckle, L. H. & Delaney, J. S (1999) Meteoritics & Planet. Sci., 32, 475. [4] Whitby, C. et al. (2000) LPS XXXI, Abstract #1732. [5] Tyra M. et al., (2007) Geochim. Cosmochim. Acta, 71, 782 [6] Toporski, J. & Steele A., (2007) Astrobiology, 7, 389 [7]Airieau, S. et al (2005) Geochim. Cosmochim. Acta, 69, 4166.

  20. Evolutionary history of CI and CM chondrites

    NASA Technical Reports Server (NTRS)

    Kerridge, J. F.; Macdougall, J. D.

    1984-01-01

    It is now clear that several different processes have acted upon various components of carbonaceous chondrites, and that at least some of those processes occurred very early in solar system history. Because these meteorites are breccias, petrographic relationships are seldom informative about the order in which those processes took place. Nonetheless, information about such an evolutionary sequence would be of potential value in defining the nature of the source region for these meteorites. Implantation of solar wind derived noble gases into CI magnetite apparently postdated the period of aqueous activity believed to be responsible for magnetite production. Carbonate crystallization roughly coincided with one or more episodes of impact driven brecciation.

  1. Reanalysis of porous chondritic cosmic dust particles

    NASA Astrophysics Data System (ADS)

    Kapisinsky, I.; Figusch, V.; Ivan, J.; Izdinsky, K.; Zemankova, M.

    2001-10-01

    The particles reanalysed in this study were obtained from the NASA Johnson Space Center (JSC) Cosmic Dust Collection. The reanalysis of the particle L2008 P9 indicates typical assemblage of olivine - pyroxene. This sample can be classified as a chondritic porous IDP with the metallic phase grain containing essential amount of nickel and copper (the latter element is most probably due to instrumental artefact). The chemical composition of the particle L2011 S5 corresponds mostly to an assemblage of pyroxene phase - (Mg,Fe,Ni)SiO_3 roughly 75 wt.% and a sulphide phase - probably pyrrhotite (Fe,Ni)S about 25 wt.%.

  2. Accretionary dark rims in unequilibrated chondrites

    NASA Astrophysics Data System (ADS)

    King, T. V. V.; King, E. A.

    1981-12-01

    Textural and qualitative EDX investigations of dark-rimmed particles in six low petrologic type chondrites indicate that the rims accreted on host particles over a wide range of temperatures prior to initial accumulation and lithification of the meteorites in which the rimmed particles are now contained. Many dark rims are enriched in moderately volatile trace elements such as Na, Cl, P, and K, relative to the host particles and matrix. The range of physical/chemical environments associated with hypervelocity impacts may have offered the setting for the formation of dark-rimmed particles early in solar system history.

  3. Chromium on Eros: Further Evidence of Ordinary Chondrite Composition

    NASA Technical Reports Server (NTRS)

    Foley, C. N.; Nittler, L. R.; Brown, M. R. M.; McCoy, T. J.; Lim, L. F.

    2005-01-01

    The surface major element composition of the near-earth asteroid 433-Eros has been determined by x-ray fluorescence spectroscopy (XRS) on the NEAR-Shoemaker spacecraft [1]. The abundances of Mg, Al, Si, Ca and Fe match those of ordinary chondrites [1]. However, the observation that Eros appears to have a sulfur abundance at least a factor of two lower than ordinary chondrites, suggests either sulfur loss from the surface of Eros by impact and/or radiation processes (space weathering) or that its surface is comprised of a somewhat more differentiated type of material than an ordinary chondrite [1]. A definitive match for an ordinary chondrite parent body has very rarely been made, despite the conundrum that ordinary chondrites are the most prevalent type of meteorite found on Earth. Furthermore, Eros is classified as an S(IV) type asteroid [2] and being an S, it is the second most prevalent type of asteroid in the asteroid belt [3].

  4. Olivine and Pyroxene Compositions in Fine-Grained Chondritic Materials

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael E.; Frank, D.

    2011-01-01

    Our analyses of the Wild-2 samples returned by the Stardust Mission have illuminated critical gaps in our understanding of related astromaterials. There is a very large database of olivine and low-calcium pyroxene compositions for coarse-grained components of chondrites, but a sparse database for anhydrous silicate matrix phases. In an accompanying figure, we present comparisons of Wild-2 olivine with the available chondrite matrix olivine major element data. We thus have begun a long-term project measuring minor as well as major element compositions for chondrite matrix and chondritic IDPs, and Wild 2 grains. Finally, we wish to re-investigate the changes to fine-grained olivine and low-Ca pyroxene composition with progressive thermal metamorphism. We have examined the LL3-4 chondrites which because of the Hayabusa Mission have become very interesting.

  5. Topics in Particle Astrophysics: Dark Matter, Gamma-Ray Bursts, and the Origin of Ultra-High-Energy Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Calvez, Antoine

    Since the first observation of cosmic rays in the early 1900's, intensive astronomical and cosmological observations, and improvements in particle detectors have generated important discoveries such as the existence of gamma-ray bursts and pulsars; they have also generated puzzling evidence for dark matter and dark energy, and for the existence of particles in the interstellar medium with energy beyond 1020 eV. In this dissertation, I will investigate some of the current theoretical challenges posed by the latest cosmological and astrophysical observations, and attempt to provide a unifying solution to the problems. X-ray and gamma-ray observations can help understand the origin of the electron and positron signals reported by ATIC, PAMELA, PPB-BETS , and Fermi. It remains unclear whether the observed high-energy electrons and positrons are produced by relic particles, or by astrophysical sources. To distinguish between the two possibilities, one can compare the electron population in the local neighborhood with that in Dwarf Spheroidal Galaxies (dSphs), which are not expected to host as many gamma-ray bursts, pulsars, or other astrophysical sources. This can be accomplished using X-ray and gamma-ray observations. Assuming the signal detected by Fermi and ATIC comes from dark matter, we calculate the photon spectrum produced by electrons via inverse Compton scattering with the Cosmic Microwave Background radiation (CMB). Since little is known about the magnetic fields in dwarf spheroidals, we consider the propagation of charged particles with and without diffusion. Extending the analysis of the Fermi collaboration for the Draco dwarf spheroidal galaxy, we find that even in the absence of diffusion, the expected gamma-ray signal lies above the upper limits set by the Fermi telescope, thus favoring astrophysical sources such as gamma-ray bursts and pulsars. Furthermore, if one assumes that a local magnetic field exists in the dwarf spheroidal galaxy, the diffusion of

  6. Origin of ΔNeff as a result of an interaction between dark radiation and dark matter

    NASA Astrophysics Data System (ADS)

    Eggers Bjaelde, Ole; Das, Subinoy; Moss, Adam

    2012-10-01

    Results from the Wilkinson Microwave Anisotropy Probe (WMAP), Atacama Cosmology Telescope (ACT) and recently from the South Pole Telescope (SPT) have indicated the possible existence of an extra radiation component in addition to the well known three neutrino species predicted by the Standard Model of particle physics. In this paper, we explore the possibility of the apparent extra dark radiation being linked directly to the physics of cold dark matter (CDM). In particular, we consider a generic scenario where dark radiation, as a result of an interaction, is produced directly by a fraction of the dark matter density effectively decaying into dark radiation. At an early epoch when the dark matter density is negligible, as an obvious consequence, the density of dark radiation is also very small. As the Universe approaches matter radiation equality, the dark matter density starts to dominate thereby increasing the content of dark radiation and changing the expansion rate of the Universe. As this increase in dark radiation content happens naturally after Big Bang Nucleosynthesis (BBN), it can relax the possible tension with lower values of radiation degrees of freedom measured from light element abundances compared to that of the CMB. We numerically confront this scenario with WMAP+ACT and WMAP+SPT data and derive an upper limit on the allowed fraction of dark matter decaying into dark radiation.

  7. Partial melting of the St. Severin (LL) and Lost City (H) ordinary chondrites: One step backwards and two steps forward

    NASA Technical Reports Server (NTRS)

    Jurewicz, A. J. G.; Jones, J. H.; Mittlefehldt, D. W.

    1994-01-01

    This study looks at partial melting in H and LL chondrites at nearly one atmosphere of total pressure as part of a continuing study of the origins of basaltic achondrites. Previously, melting experiments on anhydrous CM and CV chondrites showed that, near its solidus, the CM chondrite produced melts having major element chemistries similar to the Sioux County eucrite; but, the pyroxenes in the residuum were too iron-rich to form diogenites. Our preliminary results from melting experiments on ordinary (H, LL) chondrites suggested that, although the melts did not look like any known eucrites, pyroxenes from these charges bracketed the compositional range of pyroxenes found in diogenites. We had used the Fe/Mg exchange coefficients calculated for olivine, pyroxene, and melt in these charges to evaluate the approach to equilibrium, which appeared to be excellent. Unfortunately, mass balance calculations later indicated to us that, unlike our CM and CV charges, the LL and H experimental charges had lost significant amounts of iron to their (Pt or PtRh) supports. Apparently, pyroxene stability in chondritic systems is quite sensitive to the amount of FeO, and it was this unrecognized change in the bulk iron content which had stabilized the high temperature, highly magnesian pyroxenes. Accordingly, this work reinvestigates the phase equilibria of ordinary chondrites, eliminating iron and nickel loss, and reports significant differences. It also looks closely at how the iron and sodium in the bulk charge affect the stability of pyroxene, and it comments on how these new results apply to the problems of diogenite and eucrite petrogenesis.

  8. Chondritic xenon in the Earth’s mantle

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    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.

  9. Chondritic meteorites and the lunar surface.

    PubMed

    O'keefe, J A; Scott, R F

    1967-12-01

    The landing dynamics of and soil penetration by Surveyor I indicated that the lunar soil has a porosity in the range 0.35 to 0.45. Experiments with Surveyor III's surface sampler for soil mechanics show that the lunar soil is approximately incompressible (as the word is used in soil mechanics) and that it has an angle of internal friction of 35 to 37 degrees; these results likewise point to a porosity of 0.35 to 0.45 for the lunar soil. Combination of these porosity measurements with the already-determined radar reflectivity fixes limits to the dielectric constant of the grains of the lunar soil. The highest possible value is about 5.9, relative to vacuum; a more plausible value is near 4.3. Either figure is inconsistent with the idea that the lunar surface is covered by chondritic meteorites or other ultrabasic rocks. The data point to acid rocks, or possibly vesicular basalts; carbonaceous chondrites are not excluded. PMID:17734304

  10. Elephant Moraine 96029, a very mildly aqueously altered and heated CM carbonaceous chondrite: Implications for the drivers of parent body processing

    NASA Astrophysics Data System (ADS)

    Lee, Martin R.; Lindgren, Paula; King, Ashley J.; Greenwood, Richard C.; Franchi, Ian A.; Sparkes, Robert

    2016-08-01

    Elephant Moraine (EET) 96029 is a CM carbonaceous chondrite regolith breccia with evidence for unusually mild aqueous alteration, a later phase of heating and terrestrial weathering. The presence of phyllosilicates and carbonates within chondrules and the fine-grained matrix indicates that this meteorite was aqueously altered in its parent body. Features showing that water-mediated processing was arrested at a very early stage include a matrix with a low magnesium/iron ratio, chondrules whose mesostasis contains glass and/or quench crystallites, and a gehlenite-bearing calcium- and aluminium-rich inclusion. EET 96029 is also rich in Fe,Ni metal relative to other CM chondrites, and more was present prior to its partial replacement by goethite during Antarctic weathering. In combination, these properties indicate that EET 96029 is one of the least aqueously altered CMs yet described (CM2.7) and so provides new insights into the original composition of its parent body. Following aqueous alteration, and whilst still in the parent body regolith, the meteorite was heated to ∼400-600 °C by impacts or solar radiation. Heating led to the amorphisation and dehydroxylation of serpentine, replacement of tochilinite by magnetite, loss of sulphur from the matrix, and modification to the structure of organic matter that includes organic nanoglobules. Significant differences between samples in oxygen isotope compositions, and water/hydroxyl contents, suggests that the meteorite contains lithologies that have undergone different intensities of heating. EET 96029 may be more representative of the true nature of parent body regoliths than many other CM meteorites, and as such can help interpret results from the forthcoming missions to study and return samples from C-complex asteroids.

  11. Organic Analysis of Catalytic Fischer-Tropsch Synthesis Products and Ordinary Chondrite Meteorites by Stepwise Pyrolysis-GCMS: Organics in the Early Solar Nebula

    NASA Technical Reports Server (NTRS)

    Locke, Darren R.; Yazzie, Cyriah A.; Burton, Aaron S.; Niles, Paul B.; Johnson, Natasha M.

    2014-01-01

    Abiotic generation of complex organic compounds, in the early solar nebula that formed our solar system, is hypothesized by some to occur via Fischer-Tropsch (FT) synthesis. In its simplest form, FT synthesis involves the low temperature (<300degC) catalytic reaction of hydrogen and carbon monoxide gases to form more complex hydrocarbon compounds, primarily n-alkanes, via reactive nano-particulate iron, nickel, or cobalt, for example. Industrially, this type of synthesis has been utilized in the gas-to-liquid process to convert syngas, produced from coal, natural gas, or biomass, into paraffin waxes that can be cracked to produce liquid diesel fuels. In general, the effect of increasing reaction temperature (>300degC) produces FT products that include lesser amounts of n-alkanes and greater alkene, alcohol, and polycyclic aromatic hydrocarbon (PAH) compounds. We have begun to experimentally investigate FT synthesis in the context of abiotic generation of organic compounds in the early solar nebula. It is generally thought that the early solar nebula included abundant hydrogen and carbon monoxide gases and nano-particulate matter such as iron and metal silicates that could have catalyzed the FT reaction. The effect of FT reaction temperature, catalyst type, and experiment duration on the resulting products is being investigated. These solid organic products are analyzed by thermal-stepwise pyrolysis-GCMS and yield the types and distribution of hydrocarbon compounds released as a function of temperature. We show how the FT products vary by reaction temperature, catalyst type, and experimental duration and compare these products to organic compounds found to be indigenous to ordinary chondrite meteorites. We hypothesize that the origin of organics in some chondritic meteorites, that represent an aggregation of materials from the early solar system, may at least in part be from FT synthesis that occurred in the early solar nebula.

  12. Thermomagnetic analysis of meteorites. III - C3 and C4 chondrites

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

    Results are presented for thermomagnetic analysis in a controlled oxygen atmosphere of samples from thirteen C3 chondrites and two C4 chondrites. The examined meteorites are found to have rather diverse thermomagnetic properties, so they are placed into three groups on the basis of their thermomagnetic behavior and magnetic mineralogy: (1) those possibly containing magnetite before heating, but which display a large increase in saturation moment upon cooling to room temperature; (2) those containing magnetite as their major magnetic phase, but which show little change in saturation moment following the heating-cooling cycle; and (3) those which contain iron metal in addition to other magnetic phases. Upper limits are placed on the magnetite content of the five meteorites in group 1 by assuming that the initial saturation moment is due entirely to magnetite, and quantitative estimates of the magnetite content of the four meteorites in group 2 are determined from ambient-temperature saturation magnetization measurements. The data for the six meteorites in group 3 are discussed in terms of nickel content and troilite oxidation. It is concluded that since the magnetic and bulk mineralogies of carbonaceous chondrites are more varied and complex than indicated by whole-rock elemental analyses, the origin of such meteorites cannot be described by a simple model.

  13. Opaque Assemblages in CK and CV Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Neff, K. E.; Righter, K.

    2006-01-01

    CK carbonaceous chondrites are the only group of carbonaceous chondrites that exhibit thermal metamorphism. As a result, CKs display features of metamorphism such as silicate darkening, recrystallization and shock veins. Calcium Aluminum Inclusions and Fe-Ni metal are rare. CV carbonaceous chondrites are unequilibrated and have two subgroups; oxidized and reduced. The CV and CK carbonaceous chondrite groups have been compared to each other often because of petrographic similarities, such as overlapping oxygen isotopic ratios. Scientists have suggested the two groups of carbonaceous chondrites formed from the same parent body and CKs are equilibrated CV chondrites [1, 2]. The oxidized CV group has been most closely related to CKs. This study examines the petrology and mineralogy of CKs and CVs focusing on opaque minerals found in the meteorites. Using the oxide, metal and sulfide assemblages, constraints can be placed on the temperature and oxygen fugacity at which the meteorites equilibrated. The temperature and oxygen fugacity of the CK and CV chondrites can be compared in order to help define their formation history.

  14. Regolith and Megaregolith Formation of H-Chondrites: Thermal Constraints on the Parent Body

    NASA Astrophysics Data System (ADS)

    Akridge, Glen; Benoit, Paul H.; Sears, Derek W. G.

    1998-03-01

    Spectral reflectivity data and its location near an orbital resonance suggest that Asteroid 6 Hebe may be the source body for H-chondrites, the second largest meteorite group. Recent spacecraft images of asteroids and theoretical modeling indicate that, contrary to previous ideas, asteroids can retain thick regoliths. We model the thermal evolution of a Hebe-sized object coated with a thick insulating regolith and heated by26Al and other long-lived radionuclides. The heat conduction equations for spherically symmetric objects were solved using finite-difference approximations. We assumed a three-layer structure with regolith and megaregolith overlying a rocky core. The three layers differed in bulk density, porosity, and thermal conductivity. Interior peak temperatures were set to match metamorphic temperatures of H6 chondrites. The regolith has a major influence on thermal history, and the results are very different from those for a simple rocky body published by various authors. Regolith insulation produces a uniform interior peak temperature of ∼1250 K and moves the petrographic type boundaries close to the surface of the parent body. Petrologic types 3-6 can be produced within 10 km of the asteroid's surface with only moderate (∼1 km) regolith thicknesses. The calculations indicate that H4-H6 formation would be consistent with the cooling rate estimates and Pb-Pb formation ages if the material originated in the near surface regions. We suggest that many if not all H-chondrites could have been formed in a megaregolith and thick regolith. Their observed properties are consistent with this environment, especially the abundance of regolith breccias and H-chondrites of all petrologic types with implanted solar wind gases.

  15. Lea County 001, an H5 chondrite, and Lea County 002, an ungrouped type 3 chondrite

    SciTech Connect

    Zolensky, M.E.; Score, R.; Clayton, R.N.; Mayeda, T.K.; Schutt, J.W. Lockheed Engineering and Sciences Co., Houston, TX Chicago Univ., IL )

    1989-12-01

    A search of active deflation basins near Jal, Lea County, New Mexico resulted in the discovery of two meteorites, Lea County 001 and 002. Lea County 001 has mean olivine and low-Ca pyroxene compositions of Fa(19) and Fs(17), respectively. These and all other mineralogical and petrological data collected indicate a classification of H5 for this stone. Lea County 002 has mean olivine and low-Ca pyroxene compositions of Fa(2) and Fs(4), and is unequilibrated. Although it is mineralogically most similar to Kakangari and chondritic clasts within Cumberland Falls, the high modal amount of forsterite makes Lea County a unique type 3 chondrite. Oxygen isotope data for Lea County 002 fall on an 0-16-mixing line through those of the enstatite meteorites and IAB irons, a feature shared by Kakangari. 28 refs.

  16. The compositions of incipient shock melts in L6 chondrites

    NASA Astrophysics Data System (ADS)

    Dodd, R. T.; Jarosewich, E.

    1982-07-01

    Microprobe analyses of 33 melt pocket glasses in five L6d and L6e chondrites show them to be chemically varied but typically enriched in the constituents of plagioclase relative to the host meteorites. This enrichment appears to increase with the degree of melting, but other chemical variations among the glasses appear to be unrelated to shock intensity and melt abundance. Chemical trends for melt pocket glasses differ sharply from those reported for chondrules in ordinary chondrites. Thus partial shock melting of chondritic material is an inadequate explanation for the chemical properties of chondrules.

  17. Chondritic Meteorites: Nebular and Parent-Body Formation Processes

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.; Lindstrom, David (Technical Monitor)

    2002-01-01

    It is important to identify features in chondrites that formed as a result of parent-body modification in order to disentangle nebular and asteroidal processes. However, this task is difficult because unmetamorphosed chondritic meteorites are mixtures of diverse components including various types of chondrules, chondrule fragments, refractory and mafic inclusions, metal-sulfide grains and fine-grained matrix material. Shocked chondrites can contain melt pockets, silicate-darkened material, metal veins, silicate melt veins, and impact-melt-rock clasts. This grant paid for several studies that went far in helping to distinguish primitive nebular features from those produced during asteroidal modification processes.

  18. Labile trace elements in carbonaceous chondrites - A survey

    NASA Technical Reports Server (NTRS)

    Xiao, Xiaoyue; Lipschutz, Michael E.

    1992-01-01

    Data are presented on 14 trace elements, including Co, Au, Ga, Rb, Sb, Ag, Se, Cs, Te, Zn, Cd, Bi, Tl, and In (nearly all of which are moderately or highly labile in meteorites), obtained by radiochemical neutron activation analyses of 42 C2-C6 chondrites, all but three from Antarctica. The data indicate that carbonaceous chondrites of petrographic types 2-6 define compositional continua. It is suggested that carbonaceous C2-C6 chondrites may reflect a mixture of material that formed at low temperatures and that contained cosmic levels of highly labile elements, with material that was devoid of them.

  19. Behavior of Chromium in Chondritic Materials

    NASA Astrophysics Data System (ADS)

    Kano, N.; Matsuzaki, H.; Nogami, K.; Imamura, M.

    1996-03-01

    To survey the existence forms and existence patterns of Cr and Ru in high-temperature condensate, we have continued to carry out elemental analyses of primitive meteorites particularly acid insoluble fractions and metal phases from them. In addition, condensation calculation, which assume ideal solid solution in the multicomponent alloy, by using thermodynamic data have been performed. Noting that acid residues would contain the high-temperature condensate component, we considerd chemical compositions of acid residues by relating to the condensation process from the solar nebula. In this paper, we present the representative elemental compositions of some chondritic meteorites and discuss the implications of these data to consider the behavior of Cr in meteoritical samples.

  20. The thermoluminescence carrier in the Dhajala chondrite

    NASA Technical Reports Server (NTRS)

    Sparks, M. H.; Mckimmey, P. M.; Sears, D. W. G.

    1983-01-01

    It is pointed out that the type 3 (unequilibrated) ordinary chondrites provide a major source of information on the early solar system. However, the interpretation of the data is difficult because all but a few display signs of metamorphic alteration. The present investigation is concerned with the thermoluminescence (TL) sensitivity measurements on 58 chondrules separated from the Dhajala meteorites. The data were discussed briefly by Sparks and Sears (1982). In the current investigation particular attention is given to the constraints placed by these data on the mechanism by which metamorphism is related to TL sensitivity. Dhajala-normalized TL sensitivity of the separated chondrules is plotted against chondrule mass, and a histogram of the CaO contents of 15 chondrules is presented. Histograms showing the TL sensitivity of chondrules separated from the Dhajala meteorite are also provided.

  1. Highly 15N-Enriched Chondritic Clasts in the Isheyevo Meteorite

    SciTech Connect

    Bonal, L; Huss, G R; Krot, A N; Nagashima, K; Ishii, H A; Bradley, J P; Hutcheon, I D

    2009-01-14

    The metal-rich carbonaceous chondrites (CB and CH) have the highest whole-rock {sup 15}N enrichment ({delta}{sup 15}N up to +1500{per_thousand}), similar to {delta}{sup 15}N values reported in micron-sized regions (hotspots) of Interplanetary Dust Particles (IDPs) of possibly cometary origin and fine-grained matrices of unmetamorphosed chondrites. These {sup 15}N-rich hotspots are commonly attributed to low-temperature ion-molecule reactions in the protosolar molecular cloud or in the outer part of the protoplanetary disk. The nature of the whole-rock {sup 15}N enrichment of the metal-rich chondrites is not understood. We report a discovery of a unique type of primitive chondritic clasts in the CH/CB-like meteorite Isheyevo, which provides important constraints on the origin of {sup 15}N anomaly in metal-rich chondrites and nitrogen-isotope fractionation in the Solar System. These clasts contain tiny chondrules and refractory inclusions (5-15 {micro}m in size), and abundant ferromagnesian chondrule fragments (1-50 {micro}m in size) embedded in the partly hydrated, fine-grained matrix material composed of olivines, pyroxenes, poorly-organized aromatic organics, phyllosilicates and other hydrous phases. The mineralogy and oxygen isotope compositions of chondrules and refractory inclusions in the clasts are similar to those in the Isheyevo host, suggesting formation at similar heliocentric distances. In contrast to the previously known extraterrestrial samples, the fine-grained material in the clasts is highly and rather uniformly enriched in {sup 15}N, with bulk {delta}{sup 15}N values ranging between +1000 and +1300{per_thousand}; the {delta}{sup 15}N values in rare hotspots range from +1400 to +4000{per_thousand}. Since fine-grained matrices in the lithic clasts are the only component containing thermally unprocessed (during CAI and chondrule formation or during impact melting) materials that accreted into the metal rich chondrite parent body(ies), the {sup 15}N

  2. Metamorphosed CM and CI Carbonaceous Chondrites Could Be from the Breakup of the Same Earth-crossing Asteroid

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael; Abell, Paul; Tonui, Eric

    2005-01-01

    Far from being the relatively unprocessed materials they were once believed to be, we now know that a significant number of carbonaceous chondrites were thermally metamorphosed on their parent asteroid(s). Numerous studies indicate that 7 "CM" and 2 "CI" chondrites have been naturally heated, variously, at from 400 to over 700 C on their parent asteroid(s). Petrographic textures reveal that this thermal metamorphism occurred after the dominant aqueous alteration phase, although some meteorites show evidence of a heating event between two aqueous alteration episodes, i.e. pro- and retrograde aqueous alteration. Aside from the issues of the identification of the transient heat source, timing of metamorphism, and the relation of these materials (if any) to conventional CM and CI chondrites, there is also a mystery related to their recovery. All of these meteorites have been recovered from the Antarctic; none are falls or finds from anyplace else. Indeed, the majority have been collected by the Japanese NIPR field parties in the Yamato Mountains. In fact, one estimate is that these meteorites account for approx. 64 wt% of the CM carbonaceous chondrites at the NIPR. The reasons for this are unclear and might be due in part to simple sampling bias. However we suggest that this recovery difference is related to the particular age of the Yamato Mountains meteorite recovery surfaces, and differences in meteoroid fluxes between the Yamato meteorites and recent falls and substantially older Antarctic meteorites. Additional information is included in the original extended abstract.

  3. Using oxygen and carbon stable isotopes, 53Mn-53Cr isotope systematics, and petrology to constrain the history of carbonates and water in the CR and CM chondrite parent bodies

    NASA Astrophysics Data System (ADS)

    Tyra, Mark Anthony

    I carried out a petrologic and Mn-Cr isotopic study of carbonates in the paired CM1 chondrites, ALH 84049 and ALH 84051, in an effort to understand the origin and chronology of formation of carbonates in the most heavily altered CM chondrites. Dolomite is strongly compositionally zoned (Ca, Mg, Fe, Mn), indicating very heterogeneous formation conditions, yet all carbonate Mn-Cr analyses form individual isochrons. In this study, I also analyzed the Mn-Cr isotope systematics of the CR1 chondrite GRO 95577 and determined that siderite is the youngest secondary mineral yet observed in carbonaceous chondrites. This has implications for the CR parent body as it either was large enough to retain heat for long periods of time or was heated by impact after most aqueous alteration in carbonaceous chondrites had ceased. This study also presents analyses of carbonates in the same samples (ALH 84049 and GRO 95577) in-situ for their oxygen, and, in ALH 84049, carbon isotope composition to constrain aqueous alteration. The results show that multiple generations of carbonates must have occurred in ALH 84049 from a carbon source with either heterogeneous carbon isotopes or with changing carbon isotope compositions from ongoing methane formation. Furthermore, in GRO 95577, the oxygen isotope values suggest that calcite precipitated before siderite if CR chondrite fluids followed a closed system oxygen isotope evolution path similar to CM chondrites.

  4. An SO(10) × SO(10)' model for common origin of neutrino masses, ordinary and dark matter-antimatter asymmetries

    SciTech Connect

    Gu, Pei-Hong

    2014-12-01

    We propose an SO(10) × SO(10)' model to simultaneously realize a seesaw for Dirac neutrino masses and a leptogenesis for ordinary and dark matter-antimatter asymmetries. A (16 × 1-bar 6-bar '){sub H} scalar crossing the SO(10) and SO(10)' sectors plays an essential role in this seesaw-leptogenesis scenario. As a result of lepton number conservation, the lightest dark nucleon as the dark matter particle should have a determined mass around 15 GeV to explain the comparable fractions of ordinary and dark matter in the present universe. The (16 × 1-bar 6-bar '){sub H} scalar also mediates a U(1){sub em} × U(1)'{sub em} kinetic mixing after the ordinary and dark left-right symmetry breaking so that we can expect a dark nucleon scattering in direct detection experiments and/or a dark nucleon decay in indirect detection experiments. Furthermore, we can impose a softly broken mirror symmetry to simplify the parameter choice.

  5. Distinct Distribution of Purines in CM and CR Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Callahan, Michael P.; Stern, Jennifer C.; Glavin, Daniel P.; Smith, Karen E.; Martin, Mildred G.; Dworkin, Jason P.

    2010-01-01

    Carbonaceous meteorites contain a diverse suite of organic molecules and delivered pre biotic organic compounds, including purines and pyrimidines, to the early Earth (and other planetary bodies), seeding it with the ingredients likely required for the first genetic material. We have investigated the distribution of nucleobases in six different CM and CR type carbonaceous chondrites, including fivc Antarctic meteorites never before analyzed for nucleobases. We employed a traditional formic acid extraction protocol and a recently developed solid phase extraction method to isolate nucleobases. We analyzed these extracts by high performance liquid chromatography with UV absorbance detection and tandem mass spectrometry (HPLC-UV -MS/MS) targeting the five canonical RNAIDNA bases and hypoxanthine and xanthine. We detected parts-per-billion levels of nucleobases in both CM and CR meteorites. The relative abundances of the purines found in Antarctic CM and CR meteorites were clearly distinct from each other suggesting that these compounds are not terrestrial contaminants. One likely source of these purines is formation by HCN oligomerization (with other small molecules) during aqueous alteration inside the meteorite parent body. The detection of the purines adenine (A), guanine (0), hypoxanthine (HX), and xanthine (X) in carbonaceous meteorites indicates that these compounds should have been available on the early Earth prior to the origin of the first genetic material.

  6. Microstructure and Thermal History of Metal Particles in CH Chondrites

    NASA Technical Reports Server (NTRS)

    Goldstein, J. I.; Jones, R. H.; Kotula, P. G.; Michael, J. R.

    2005-01-01

    Fe-Ni metal particles with smooth Ni, Co, and Cr zoning patterns, 8-13 wt.% Ni in the center of the particle to 3-5 wt% Ni at the rim, have been identified in several CR-clan (CH, Bencubbinlike, and CR) chondrites. These zoning patterns are broadly consistent with an origin by gas-solid condensation in the solar nebula at temperatures between approximately 1500 to 1300 K and fast cooling rates, 2 to 25 K/day. Apparently, this condensate metal was not melted during chondrule formation or affected significantly in the solid-state by alteration during parent body processing. Consideration of diffusional redistribution of Ni, Co, Cr and siderophile elements have further constrained the calculated condensation temperatures and cooling rates of the zoned condensates. These condensate metals have irregular shapes and vary in size from 50 to 350 m as revealed in some detail by optical and SEM techniques. In addition to zoned condensate particles, other types of metal particles have been observed. These include zoned condensates with exsolution-precipitates, unzoned homogeneous metal with no exsolution precipitates, unzoned metal exhibiting exsolution precipitates and high Ni metal grains.

  7. Rare Earth Element Complementarity in CO and CV Chondrites

    NASA Astrophysics Data System (ADS)

    Crapster-Pregont, E. J.; Friedrich, J. M.; Ebel, D. S.

    2014-09-01

    LREE/HREE ratios in each component of CO and CV chondrites combine to produce complementary, flat bulk REE pattern, while individually yielding insight into mineral controls and precursor characteristics.

  8. Non-Destructive Classification Approaches for Equilibrated Ordinary Chondrites

    NASA Astrophysics Data System (ADS)

    Righter, K.; Harrington, R.; Schroeder, C.; Morris, R. V.

    2013-09-01

    In order to compare a few non-destructive classification techniques with the standard approaches, we have characterized a group of chondrites from the Larkman Nunatak region using magnetic susceptibility and Mössbauer spectroscopy.

  9. A Common Parent for IIE Iron Meteorite and H Chondrites

    NASA Astrophysics Data System (ADS)

    Teplyakova, S. N.; Humayun, M.; Lorenz, C. A.; Ivanova, M. A.

    2012-03-01

    We report new siderophile element abundances for the metal in the IIE irons — Watson, Tobychan, Elga, Verkhne Dnieprovsk, and Miles — to examine the possible genetic relations between IIE metal and H chondritic precursors.

  10. Characterization of Luminescent Minerals in CM2 Chondrite (Jbilet Winselwan)

    NASA Astrophysics Data System (ADS)

    Kiku, Y. K.; Ohgo, S. O.; Nishido, H. N.

    2014-09-01

    We have characterized luminescent minerals of forsterite, diopside and spinel in the CM2 chondrite (Jbilet Winselwan) using SEM-CL and to discuss the formation of the luminescent minerals under aqueous conditions.

  11. Ordinary chondrites - Multivariate statistical analysis of trace element contents

    NASA Technical Reports Server (NTRS)

    Lipschutz, Michael E.; Samuels, Stephen M.

    1991-01-01

    The contents of mobile trace elements (Co, Au, Sb, Ga, Se, Rb, Cs, Te, Bi, Ag, In, Tl, Zn, and Cd) in Antarctic and non-Antarctic populations of H4-6 and L4-6 chondrites, were compared using standard multivariate discriminant functions borrowed from linear discriminant analysis and logistic regression. A nonstandard randomization-simulation method was developed, making it possible to carry out probability assignments on a distribution-free basis. Compositional differences were found both between the Antarctic and non-Antarctic H4-6 chondrite populations and between two L4-6 chondrite populations. It is shown that, for various types of meteorites (in particular, for the H4-6 chondrites), the Antarctic/non-Antarctic compositional difference is due to preterrestrial differences in the genesis of their parent materials.

  12. Thermomagnetic analysis of meteorites, 2. C2 chondrites

    USGS Publications Warehouse

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

    1975-01-01

    Samples of all eighteen of the known C2 chondrites have been analyzed thermomagnetically. For eleven of these, initial Fe3O4 content is low (generally <1%) and theJs-T curves are irreversible. The heating curves show variable greater (up to 10 times) than it is initially. This behavior is attributed to the production of magnetite from a thermally unstable phase - apparently FeS. Four of the remaining seven C2 chondrites contain Fe3O4 as the only significant magnetic phase: initial magnetite contents range from 4 to 13%. The remaining three C2 chondrites contain iron or nickel-iron in addition to Fe3O4. These seven C2 chondrites show little evidence of the breakdown of a thermally unstable phase. ?? 1975.

  13. Microstructure and Thermal History of Metal Particles in CH Chondrites

    NASA Astrophysics Data System (ADS)

    Goldstein, J. I.; Jones, R. H.; Kotula, P. G.; Michael, J. R.

    2005-03-01

    This paper provides detailed microstructural and microchemical information at the nm to µm scale (SEM, EPMA, TEM, EBSD) for a select suite of metal particles in four CH chondrites, ALH 85085, PAT 91546, Acfer 214, NWA 739.

  14. Petrology and Bulk Chemistry of R Chondrites: New Data

    NASA Astrophysics Data System (ADS)

    Isa, J.; Rubin, A. E.; Wasson, J. T.

    2010-03-01

    New INAA data show that R chondrites of all petrologic types are isochemical. R3 PRE 95411 contains numerous awaruite grains; R6 Y 980702 has a fine-grained granoblastic matrix; MET 01149 is reclassified as R3.

  15. Crystallinity of Fe-Ni Sulfides in Carbonaceous Chondrites

    NASA Astrophysics Data System (ADS)

    Zolensky, M. E.; Ohsumi, K.; Mikouchi, T.; Hagiya, K.; Le, L.

    2008-03-01

    We examine the crystallinity and crystal structures of Fe-Ni sulfides in five carbonaceous chondrites - Acfer 094 (CM2), Tagish Lake (C2 ungrouped), Kaidun C1, Bali (CV2/3 oxidized), and Efremovka (CV3 reduced).

  16. Evolution of carbonaceous chondrite parent bodies: Insights into cometary nuclei

    NASA Technical Reports Server (NTRS)

    Mcsween, Harry Y., Jr.

    1989-01-01

    It is thought that cometary samples will comprise the most primitive materials that are able to be sampled. Although parent body alteration of such samples would not necessarily detract from scientists' interest in them, the possibility exists that modification processes may have affected cometary nuclei. Inferences about the kinds of modifications that might be encountered can be drawn from data on the evolution of carbonaceous chondrite parent bodies. Observations suggest that, of all the classes of chondrites, these meteorites are most applicable to the study of comets. If the proportion of possible internal heat sources such as Al-26 in cometary materials are similar to those in chondrites, and if the time scale of comet accretion was fast enough to permit incorporation of live radionuclides, comets might have had early thermal histories somewhat like those of carbonaceous chondrite parent bodies.

  17. Mechanical aggregation of enstatite chondrites from an inhomogeneous debris cloud

    NASA Technical Reports Server (NTRS)

    Leitch, C. A.; Smith, J. V.

    1981-01-01

    Enstatite chondrites have oxygen isotope ratios closer to those of the earth and moon than other meteorites. Their minerals are chemically reduced; metal contains Si, and some Ca, Ti, Mg and Mn are incorporated in sulphides rather than silicates. Clinoenstatite and olivine are virtually Fe-free. Two types of clinoenstatite in the Indarch enstatite chondrite have been reported, one luminescing blue and one red. Similar clinoenstatites in the Kota-Kota enstatite chondrite are associated with two distinct types of forsteritic olivine, one luminescing orange and the other blue. The textural relations and differences in chemical composition cannot be explained by progressive condensation from the solar nebula and require the mechanical mixing of material from at least two sources. It is suggested here that enstatite chondrites result from mechanical and chemical processes during aerodynamic sorting and gravitational settling of debris from a hot cloud of dust, liquid and gas produced during collision of planetesimals.

  18. Partial Melting of Ordinary Chondrite Under Reducing Conditions

    NASA Astrophysics Data System (ADS)

    Ford, R.; Rushmer, T.; Benedix, G.; McCoy, T.

    2004-12-01

    A critical parameter in determining the nature and processes of differentiation of planetary materials in the early solar system is oxygen fugacity. Chondrites record a range of oxygen fugacities from approximately 5 log units below the iron-wustite (Fe-FeO) buffer (enstatite chondrites) to close to QFM (some carbonaceous chondrites). Among the equilibrated chondrites, an "oxidation gap" appears to exist between ordinary chondrites and enstatite chondrites, although several groups of unequilibrated carbonaceous chondrites appear to occupy this "gap". Some primitive achondrites fill this gap (e.g. pallasites, acapulcoites, lodranites, winonaites, and silicate-bearing IAB and IIE irons), although the precursors to these groups are poorly known. In this experimental study, we have determined the modification in mineral compositions during partial melting under reducing conditions and explore the idea that the primitive achondrites may be formed through differentiation under reducing conditions of a more oxidized precursor. Partial melting experiments were conducted on an H6 chondrite (Kernouve) under reducing conditions at 1 atm and at 1.3 GPa pressure in a solid media deformation apparatus. In the 1 atm experiments, fO2 was buffered by gas mixing and sealed silica tube techniques to values determined from thermodynamic calculations of primitive achondrites; in the deformation experiments, aluminum jackets were used. The experiments suggest that partial melting of an oxidized precursor under reducing conditions can produce some of the reduced features observed in primitive achondrites such as magnesian olivine, pyroxene and chromite compositions typical of primitive achondrites at temperatures of 1200-1300 ° C, as well as chalcophilic behavior of previously lithophillic ions (e.g., Cr in sulfide) at temperatures at 1000° C. Some features of primitive achondrites (e.g. oxygen isotopic compositions and Cr/(Cr+Al) ratios of chromites) appear to be intrinsic to the

  19. The Bloomington (LL6) chondrite and its shock melt glasses

    NASA Astrophysics Data System (ADS)

    Dodd, R.; Olsen, E. J.; Clarke, R. S., Jr.

    1985-09-01

    The shock melt glasses of the Bloomington LL-group chondrite were examined using electron-beam microscopy and compared with data from studies of other shock melt glasses. Petrologic and mineralogic characterizations were also performed of the samples. The metal contents of the meteorite were almost wholly Ni-rich martensite. The glasses resembled shock melt glasses in L-group chondrites, and were indicative of isochemical melting during one melt phase, i.e., a very simple history.

  20. Thorium and uranium abundances in the Jilin H5 chondrite

    NASA Astrophysics Data System (ADS)

    Pernicka, E.

    1985-02-01

    Thorium and uranium abundances have been measured in the Jilin H5 chondrite by radiochemical neutron activation analysis. Although the abundances of (35.8 + or - 1.5) ppb Th and (14.9 + or - 0.9) ppb U are within the range of literature values, the ratio Th/U is about 25 percent lower than the average value for H chondrites. Terrestrial addition of uranium appears to be the most likely explanation.

  1. Evidence that Polycyclic Aromatic Hydrocarbons in Two Carbonaceous Chondrites Predate Parent-Body Formation

    NASA Technical Reports Server (NTRS)

    Plows, F. L.; Elsila, J. E.; Zare, R. N.; Buseck, P. R.

    2003-01-01

    Organic material in meteorites provides insight into the cosmochemistry of the early solar system. The distribution of polycyclic aromatic hydrocarbons (PAHs) in the Allende and Murchison carbonaceous chondrites was investigated using spatially resolved microprobe laser-desorption laser-ionization mass spectrometry. Sharp chemical gradients of PAHs are associated with specific meteorite features. The ratios of various PAH intensities relative to the smallest PAH, naphthalene, are nearly constant across the sample. These findings suggest a common origin for PAHs dating prior to or contemporary with the formation of the parent body, consistent with proposed interstellar formation mechanisms.

  2. C/N and other Elemental Ratios of Chondritic Porous IDPS and a Fluffy Concordia Micrometeorite

    NASA Technical Reports Server (NTRS)

    Smith, T.; Nakamura-Messenger, K.; Messenger, S.; Keller, L. P.; Khodja, H.; Raepsaet, C.; Wirick, S.; Flynn, G. J.; Taylor, S.; Engrand, C.; Duprat, J.; Herzog, G. F.

    2013-01-01

    Chondritic porous interplanetary dust particles (CP-IDPs) may be cometary in origin [1], as may ultracarbona-ceous (UCAMMs) [2] and 'fluffy' [3] micrometeorites from the Concordia collection. They are all rich in organics, which can rim grains and may have helped glue grains together during accretion [4]. The organics also contain nitrogen the input of which to Earth has potential biological importance. We report C/N ratios, and other properties of CP-IDPs and a Concordia fluffy microme-teorite.

  3. Redetermination of parameters for semi-empirical model for spallogenic He and Ne in chondrites

    NASA Technical Reports Server (NTRS)

    Nyquist, L. E.; Mcdowell, A. F.

    1986-01-01

    A semi-empirical model described previously satisfactorily reproduced a number of shielding-dependent variations in the relative production rates of spallogenic He and Ne in chondrites. However, data for cores of the Keyes and St. Severin meteorites showed a subsurface build-up in He-3 which was not predicted with the original model parameters and the model was not pursued. Renewed interest in the preatmospheric size of meteorites, spurred in part by the desirability of understanding the exposure history of the SNC meteorites, justifies redetermination of model parameters.

  4. Do We Already have Samples of CERES H Chondrite Haliites and the CERES-HEBE Link

    NASA Technical Reports Server (NTRS)

    Fries, Marc D.; Messenger, S.; Steele, A.; Zolensky, M.

    2013-01-01

    We investigate the hypothesis that halite grains in the brecciated H chondrites Zag and Monahans originate from Ceres. Evidence includes mineralogy of the halites consistent with formation on a large, carbonaceous, aqueously active body close to the H chondrite parent body >4 Ga ago. Evidence also includes orbital simularities between 1 Ceres and the purported H chondrite parent body (HPB) 6 Hebe, possibly facilitating a gentle transfer between the bodies. Halite grains in the Monahans and Zag Hchondrites are exogenous to the H chondrite parent body and were transported to the HPB >4 Ga ago. Examination of minerals and carboanceous materials entrained within the halites shows that the halite parent body (HaPB) is consistent with a carbonaceous body [1]. It is probably a large body due to the variety of entrained carbonaceous materials which probably accreted from multiple sources. The halite grains contain intact, HaPB-origin, ancient fluid inclusions indicating that transfer between the HaPB and the HPB was a gentle process resulting in a ?T of <25 degC. Ejection from the HaPB may have been via cryovolcanic processes similar to those on modern-day Enceladus, which have been interpreted to include halite from spectroscopic observations. The ?Tmax to preserve the brinebearing halite restricts the impact velocity to the HPB at less than ˜350-700 m/s, depending upon the fraction of kinetic energy used heat the sample. [2-6]. Therefore the HaPB and HPB must have shared nearby orbits at the time of the HaPB-HPB transfer. Evidence presented elsewhere indicates asteroid 6 Hebe is a favored candidate for the HPB based on reflectance spectrum similarity with H chondrites and dynamical arguments [7,8]. The modern orbits of Ceres and Hebe are reasonably similar, with aphelion/perihelion of Ceres and Hebe of 2.99/2.55 and 2.91/1.94 AU, respectively. Initial calculations indicate an approximate mean infall velocity of 1.20 to 1.38 km/s. While higher than 350- 700 m/s, the

  5. Chondrules in the Qingzhen type-3 enstatite chondrite Possible precursor components and comparison to ordinary chondrite chondrules

    NASA Astrophysics Data System (ADS)

    Grossman, J. N.; Rubin, A. E.; Rambaldi, E. R.; Rajan, R. S.; Wasson, J. T.

    1985-08-01

    The mineral composition of chondrules from a fragment of Qingzhen (EH3) fall was analyzed by neutron activation method. Unlike the ordinary chondrite (OC) chondrules (Gooding and Keil, 1981), the Qingzhen radial pyroxene (RP) and porphyritic pyroxene (PP) chondrules have similar bulk compositions. Porphyritic olivine-pyroxene (POP) chondrules are richer than PP and RP chondrules in refractory lithophiles and siderophiles. Elements in each of the following sets intercorrelate significantly: (1) Fe-Co-Ni-Ir-Au, probably derived from a metal component; (2) Ca-Eu-Se, which suggests an oldhamite-rich precursor; (3) Al-Sc-Hf, occurring in high concentrations in POP chondrules, this set suggesting the existence of a refractory lithophile-rich and olivine-rich component; (4) Na REE; and (5) Cl-Br. Sets (2) and (4) were not precursors of OC. The interelement ratios of refractory lithophiles such as Ca, Al, Ti, Sc, and REE are similar to CI ratios, suggesting that they originated in the earliest phases as silicates, which were sulfurized before chondrule formation.

  6. Rhenium-osmium isotope systematics of carbonaceous chondrites

    USGS Publications Warehouse

    Walker, R.J.; Morgan, J.W.

    1989-01-01

    Rhenium and osmium concentrations and Os isotopic compositions of eight carbonaceous chondrites, one LL3 ordinary chondrite, and two iron meteorites were determined by resonance ionization mass spectrometry. Iron meteorite 187Re/186Os and 187OS/186Os ratios plot on the previously determined iron meteorite isochron, but most chondrite data plot 1 to 2 percent above this meteorite isochron. This suggests either that irons have significantly younger Re-Os closure ages than chondrites or that chondrites were formed from precursor materials with different chemical histories from the precursors of irons. Some samples of Semarkona (LL3) and Murray (C2M) meteorites plot 4 to 6 percent above the iron meteorite isochron, well above the field delineated by other chondrites. Murray may have lost Re by aqueous leaching during its preterrestrial history. Semarkona could have experienced a similar loss of Re, but only slight aqueous alteration is evident in the meteorite. Therefore, the isotopic composition of Semarkona could reflect assembly of isotopically heterogeneous components subsequent to 4.55 billion years ago or Os isotopic heterogeneities in the primordial solar nebula.

  7. Sulfide-rich metallic impact melts from chondritic parent bodies

    NASA Astrophysics Data System (ADS)

    Schrader, Devin L.; Lauretta, Dante S.; Connolly, Harold C. _jr., Jr.; Goreva, Yulia S.; Hill, Dolores H.; Domanik, Ken J.; Berger, Eve L.; Yang, Hexiong; Downs, Robert T.

    2010-05-01

    Sacramento Wash 005 (SaW) 005, Meteorite Hills 00428 (MET) 00428, and Mount Howe 88403 (HOW) 88403 are S-rich Fe,Ni-rich metal meteorites with fine metal structures and homogeneous troilite. We compare them with the H-metal meteorite, Lewis Cliff 88432. Phase diagram analyses suggest that SaW 005, MET 00428, and HOW 88403 were liquids at temperatures above 1350°C. Tridymite in HOW 88403 constrains formation to a high-temperature and low-pressure environment. The morphology of their metal-troilite structures may suggest that MET 00428 cooled the slowest, SaW 005 cooled faster, and HOW 88403 cooled the quickest. SaW 005 and MET 00428 contain H-chondrite like silicates, and SaW 005 contains a chondrule-bearing inclusion that is texturally and compositionally similar to H4 chondrites. The compositional and morphological similarities of SaW 005 and MET 00428 suggest that they are likely the result of impact processing on the H-chondrite parent body. SaW 005 and MET 00428 are the first recognized iron- and sulfide-rich meteorites, which formed by impact on the H-chondrite parent body, which are distinct from the IIE-iron meteorite group. The morphological and chemical differences of HOW 88403 suggest that it is not from the H-chondrite body, although it likely formed during an impact on a chondritic parent body.

  8. Origin and composition of sediment organic matter in a coastal semi-enclosed ecosystem: An elemental and isotopic study at the ecosystem space scale