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Sample records for meteorite parent bodies

  1. Meteorites and their parent bodies: Evidence from oxygen isotopes

    NASA Technical Reports Server (NTRS)

    Clayton, R. N.

    1978-01-01

    Isotopic abundance variations among meteorites are used to establish genetic associations between meteorite classes. Oxygen isotope distributions between group II E irons with H-group ordinary chondrites and enstatic meteorites indicate that the parent bodies were formed out of pre-solar material that was not fully mixed at the time condensation occurred within the solar nebula.

  2. Meteoritic Amino Acids: Diversity in Compositions Reflects Parent Body Histories

    PubMed Central

    2016-01-01

    The analysis of amino acids in meteorites dates back over 50 years; however, it is only in recent years that research has expanded beyond investigations of a narrow set of meteorite groups (exemplified by the Murchison meteorite) into meteorites of other types and classes. These new studies have shown a wide diversity in the abundance and distribution of amino acids across carbonaceous chondrite groups, highlighting the role of parent body processes and composition in the creation, preservation, or alteration of amino acids. Although most chiral amino acids are racemic in meteorites, the enantiomeric distribution of some amino acids, particularly of the nonprotein amino acid isovaline, has also been shown to vary both within certain meteorites and across carbonaceous meteorite groups. Large l-enantiomeric excesses of some extraterrestrial protein amino acids (up to ∼60%) have also been observed in rare cases and point to nonbiological enantiomeric enrichment processes prior to the emergence of life. In this Outlook, we review these recent meteoritic analyses, focusing on variations in abundance, structural distributions, and enantiomeric distributions of amino acids and discussing possible explanations for these observations and the potential for future work. PMID:27413780

  3. Meteoritic Amino Acids: Diversity in Compositions Reflects Parent Body Histories.

    PubMed

    Elsila, Jamie E; Aponte, José C; Blackmond, Donna G; Burton, Aaron S; Dworkin, Jason P; Glavin, Daniel P

    2016-06-22

    The analysis of amino acids in meteorites dates back over 50 years; however, it is only in recent years that research has expanded beyond investigations of a narrow set of meteorite groups (exemplified by the Murchison meteorite) into meteorites of other types and classes. These new studies have shown a wide diversity in the abundance and distribution of amino acids across carbonaceous chondrite groups, highlighting the role of parent body processes and composition in the creation, preservation, or alteration of amino acids. Although most chiral amino acids are racemic in meteorites, the enantiomeric distribution of some amino acids, particularly of the nonprotein amino acid isovaline, has also been shown to vary both within certain meteorites and across carbonaceous meteorite groups. Large l-enantiomeric excesses of some extraterrestrial protein amino acids (up to ∼60%) have also been observed in rare cases and point to nonbiological enantiomeric enrichment processes prior to the emergence of life. In this Outlook, we review these recent meteoritic analyses, focusing on variations in abundance, structural distributions, and enantiomeric distributions of amino acids and discussing possible explanations for these observations and the potential for future work. PMID:27413780

  4. Meteoritic Amino Acids: Diversity in Compositions Reflects Parent Body Histories.

    PubMed

    Elsila, Jamie E; Aponte, José C; Blackmond, Donna G; Burton, Aaron S; Dworkin, Jason P; Glavin, Daniel P

    2016-06-22

    The analysis of amino acids in meteorites dates back over 50 years; however, it is only in recent years that research has expanded beyond investigations of a narrow set of meteorite groups (exemplified by the Murchison meteorite) into meteorites of other types and classes. These new studies have shown a wide diversity in the abundance and distribution of amino acids across carbonaceous chondrite groups, highlighting the role of parent body processes and composition in the creation, preservation, or alteration of amino acids. Although most chiral amino acids are racemic in meteorites, the enantiomeric distribution of some amino acids, particularly of the nonprotein amino acid isovaline, has also been shown to vary both within certain meteorites and across carbonaceous meteorite groups. Large l-enantiomeric excesses of some extraterrestrial protein amino acids (up to ∼60%) have also been observed in rare cases and point to nonbiological enantiomeric enrichment processes prior to the emergence of life. In this Outlook, we review these recent meteoritic analyses, focusing on variations in abundance, structural distributions, and enantiomeric distributions of amino acids and discussing possible explanations for these observations and the potential for future work.

  5. Comparison of lunar rocks and meteorites: Implications to histories of the moon and parent meteorite bodies

    NASA Technical Reports Server (NTRS)

    Prinz, M.; Fodor, R. V.; Keil, K.

    1977-01-01

    There are many similarities between lunar samples and stone meteorites. Lunar samples, especially from the highlands, indicate that they have been affected by complex and repeated impact processes. Similar complex and repeated impact processes have also been operative on the achondritic and chondritic meteorites. Similarities between lunar and meteoritic rocks are discussed as follows: (1) Monomict and polymict breccias occur in lunar rocks, as well as in achondritic and chondritic meteorites, having resulted from complex and repeated impact processes; (2) Chondrules are present in lunar meteorites, as well as in a few achondritic and most chondritic meteorites. They apparently crystallized spontaneously from molten highly supercooled droplets which may have formed from impact melts or, perhaps, volcanic processes (as well as from the solar nebula, in the case of meteoritic chondrites); (3) Lithic fragments vary from little modified (relative to the apparent original texture) to partly or completely melted and recrystallized lithic fragments. Their detailed study allows conclusions to be drawn about their parent rock types and their origin, thereby gaining insight into preimpact histories of lunar and meteoritic breccias. There is evidence that cumulate rocks were involved in the early history of both moon and parent meteorite bodies.

  6. Fractionation and Accretion of Meteorite Parent Bodies

    NASA Technical Reports Server (NTRS)

    Weidenschilling, Stuart J.

    2005-01-01

    Senior Scientist Stuart J. Weidenschilling presents his final administrative report for the research program on which he was the Principal Investigator. The research program resulted in the following publications: 1) Particle-gas dynamics and primary accretion. J. N. Cuzzi and S. J . Weidenschilling. To appear in Meteorites and the Early Solar System 11 (D. Lauretta et a]., Eds.), Univ. Arizona Press. 2005; 2) Timescales of the solar protoplanetary disk. S. Russell, L. Hartmann, J . N. Cuzzi, A. Krot, M. Gounelle and S. J. Weidenschilling. To appear in Meteorites and the Early Solar System II (D. Lauretta et al., Eds.), Univ. Arizona Press, 2005; 3) Nebula evolution of thermally processed solids: Reconciling astrophysical models and chondritic meteorites. J. N. Cuzzi, F. J. Ciesla, M. I. Petaev, A. N. Krot, E. R. D. Scott and S . J. Weidenschilling. To appear in Chondrites and the Protoplanetary Disk (A. Krot et a]., Eds.), ASP Conference Series, 2005; 4) Possible chondrule formation in planetesimal bow shocks: Physical processes in the near vicinity of the planetesimal. L. L. Hood, F. J. Ciesla and S. J. Weidenschilling. To appear in Chondrites and the Protoplanetary Disk (A. Krot et al., Eds.), ASP Conference Series, 2005; 5) From icy grains to comets. In Comets II (M. Festou et al., Eds.), Univ. Arizona Press, pp. 97- 104, 2005; 6) Evaluating planetesimal bow shocks as sites for chondrule formation. F. J . Ciesla, L. L. Hood and S. J. Weidenschilling. Meteoritics & Planetary Science 39, 1809-1 821, 2004; and 7) Radial drift of particles in the solar nebula: Implications for planetesimal formation. Icarus 165, 438-442, 2003.

  7. Chondritic Meteorites: Nebular and Parent-Body Formation Process

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.

    1997-01-01

    Chondritic meteorites are the products of condensation, agglomeration and accretion of material in the solar nebula; these objects are the best sources of information regarding processes occurring during the early history of the solar system. We obtain large amounts of high-quality chemical and petrographic data and use them to infer chemical fractionation processes that occurred in the solar nebula and on meteorite parent bodies during thermal metamorphism, shock metamorphism and aqueous alteration. We compare diverse groups of chondrites and model their different properties in terms of processes that differed at different nebular locations or on different parent-bodies. In order to expand our set of geochemically important elements (particularly Si, C, P and S) and to distinguish the different oxidation states of Fe, Greg Kallemeyn spent three months (1 Sept. - 30 Nov. 1995) at the Smithsonian Institution to learn Eugene Jarosewich's wet chemical techniques. Key specimens from the recently established CK, CR and R chondrite groups were analyzed.

  8. Magnetic Study of Paris Meteorite: a Partially Differentiated Parent Body?

    NASA Astrophysics Data System (ADS)

    Cournède, C.; Gattacceca, J.; Rochette, P.; Zanda, B.

    2011-12-01

    The Paris meteorite is a unique carbonaceous CM chondrite find with almost no traces of terrestrial weathering [1]. Contrary to others CM chondrites, that contain abundant magnetite formed during aqueous alteration on their parent body, Paris is characterized by the coexistence of magnetite and abundant metallic Fe-Ni. We conducted a magnetic study (magnetic properties and paleomagnetism) of several oriented samples of this meteorite, with masses ranging from several mg up to 17 g. Preliminary rock magnetism results confirm that Paris has a magnetic mineralogy that is notably different from that of other CM chondrites, with a dominant FeNi metal, and minor magnetite. This corroborate that Paris suffered less aqueous alteration than other CM chondrites. Anisotropy of magnetic susceptibility shows that Paris is also one of the most anisotropic CM chondrite, and that it has a homogeneous fabric at least at the centimeter-scale. The comparison of the remanent magnetization obtained for metal-rich and magnetite-rich samples may have provided constraints on the magnetic fields present before and after accretion respectively. Unfortunately, paleomagnetic data show that the meteorite has been exposed to strong artificial magnetic field (magnet), precluding the study of the possible soft natural magnetization carried by FeNi. However, a high-coercivity magnetization is still preserved in the meteorite. It is homogeneous in direction and intensity at the scale of the meteorite. We interpret it as a pre-terrestrial component acquired on the parent body in a field on 3 ± 1 μT (estimated with the method described in [2]). In view of its coercivity (up to 120 mT) we suppose that this magnetization is carried by fine-grained magnetite (although thermal and chemical demagnetization experiments are needed to confirm this hypothesis). In this case, because crystallization of magnetite likely occurred several Myr after the formation of the solar system [3], i.e. after the possible

  9. Partial melting on the acapulcoite-lodranite meteorite parent body

    NASA Astrophysics Data System (ADS)

    McCoy, Timothy James

    1994-01-01

    Many asteroids experienced partial melting and incomplete differentiation. Our knowledge of the detailed of these processes are incomplete, owing to the paucity of partially melted meteorites. 1 studied two groups of meteorites which originated on a common parent body and are residues of a wide range of partial melting acapulcoites and lodranites. These meteorites formed from a chemically and isotopically heterogeneous precursor chondrite. Heating and cooling occurred early in the history of the solar system, as evidenced by the approximately 4.51 Ga 39 Ar40Ar age of acapulcoites and the approximately 4.48 Ga39Ar40Ar age of the lodranite Gibson. The heating was probably caused by non-collisional heat sources. Acapulcoites (Acapulco, Monument Draw, Yamato 74063, ALH A77081, ALH A81261, ALH A81315, ALH 78230, ALH A81187 and ALH 84190) formed by low degrees of partial melting (e.g., Fe, Ni-FeS eutectic melting, but not silicate partial melting). Fe, Ni-FeS partial melts concentrated into micron- to centimeter-sized veins, but migration distances were short. In contrast, lodranites (Lodran, Gibson, Yamato 791491, Yamato 791493, Yamato 74357, Yamato 8002, Yamato 75274, MAC 88177, LEW 88280, EET 84302 and FRO 90011) experienced higher degrees of partial melting, including silicate partial melting. The higher degree of partial melting allowed efficient melt migration, depleting the residues in plagioclase and troilite. Volatiles played a major role in melt migration, driving partial melts to the surface where they were erupted at greater than the escape velocity and lost into space, Thus, basaltic partial melts are not sampled as discrete meteorites. In one meteorite (LEW 86220), these basaltic, Fe, Ni, FeS-rich partial melts from a lodranite source region were injected into a cooler, acapulcoite region. The acapulcoite-lodranite parent body experienced a range of partial melting and melt migration. Cooling of this body may have been complex, with slow cooling at high

  10. Early aqueous activity on primitive meteorite parent bodies.

    PubMed

    Endress, M; Zinner, E; Bischoff, A

    1996-02-22

    The interstellar material from which the solar system formed has been modified by many processes: evaporation and condensation in the solar nebula, accretion into protoplanetary bodies and post-accretion processes within these bodies. Meteorites provide a record of these events and their chronology. Carbonaceous CI chondrites are among the most primitive, undifferentiated meteorites, but nevertheless show evidence of post-accretion alteration; they contain carbonates that are believed to have formed by reactions between anhydrous CI precursor materials and circulating fluids in the meteorite parent body (or bodies), yet little is known about the nature of these reactions or the timescale on which they occurred. Here we report measurements of excess 53Cr--formed by the decay of short-lived 53Mn--in five carbonate fragments from the CI chondrites Orgueil and Ivuna. Our results show that aqueous alteration on small protoplanetary bodies must have begun less than 20 Myr after the time of formation of the oldest known solar-nebula condensates (Allende refractory inclusions). This upper limit is much shorter than that of 50 Myr inferred from previous studies, and clearly establishes aqueous alteration as one of the earliest processes in the chemical evolution of the solar system.

  11. 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.

  12. The breakup of a meteorite parent body and the delivery of meteorites to earth

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    Whether many of the 10,000 meteorites collected in the Antarctic are unlike those falling elsewhere is contentious. The Antarctic H chondrites, one of the major classes of stony meteorites, include a number of individuals with higher induced thermoluminescence peak temperatures than observed among non-Antarctic H chondrites. The proportion of such individuals decreases with the mean terrestrial age of the meteorites at the various ice fields. These H chondrites have cosmic-ray exposure ages of about 8 million years, experienced little cosmic-ray shielding, and suffered rapid postmetamorphic cooling. Breakup of the H chondrite parent body, 8 million years ago, may have produced two types of material with different size distributions and thermal histories. The smaller objects reached earth more rapidly through more rapid orbital evolution.

  13. Aqueous alteration of meteorite parent bodies: Possible role of unfrozen water and the Antarctic meteorite analogy

    NASA Technical Reports Server (NTRS)

    Gooding, J. L.

    1984-01-01

    Based on oxygen isotrophy the alteration of CM2 chondrites could occur at or near O C (273 K). Such a scenario can be understood if C chondrite parent bodies evolved as rock/ice mixtures that contained unfrozen (mobile or quasi-liquid below 273K) pure water, a well known phenomenon in cold soils on Earth. The importance of unfrozen water diagenesis in C chondrite history can be tested by a combined program of experimental simulations and petrologic study of analogous features developed by weathering of meteorites in or an Antarctic ice.

  14. Nature and evolution of the meteorite parent bodies: Evidence from petrology and metallurgy

    NASA Technical Reports Server (NTRS)

    Wood, J. A.

    1978-01-01

    The physical as well as chemical properties of the meteorite parent bodies are reviewed and it is concluded that many differentiated meteorites were likely formed in asteroidal-sized parents. A new model is developed for the formation of pallasites at the interface between an iron core and olivine mantle in differentiated bodies only about 10 km in diameter, which are later incorporated into a second generation of larger (100 km) parent bodies.

  15. The early formation of the IVA iron meteorite parent body

    NASA Astrophysics Data System (ADS)

    Blichert-Toft, Janne; Moynier, Frédéric; Lee, Cin-Ty A.; Telouk, Philippe; Albarède, Francis

    2010-08-01

    The IVA iron meteorites are magmatic cumulates from the core of a small asteroid, which broke apart ˜ 400 Ma ago. As the depletion of this planetary body in volatile elements is expected to be reflected in high U/Pb ratios of its minerals, we embarked on analyzing the isotope composition of Pb in the cm-sized troilite inclusions of Muonionalusta and Gibeon, both iron meteorites belonging to the IVA family. The bulk of the data for nine troilite subsamples of Muonionalusta scatter with an apparent age of 4.57 Ga, which is shown to reflect the presence of both primordial and common terrestrial Pb components, in addition to radiogenic Pb. The most radiogenic subsample, however, has fractions with 206Pb/ 204Pb ratios as high as over 1000 and gives a statistically significant 207Pb*/ 206Pb* age of 4565.3 ± 0.1 Ma (MSWD = 0.08), consistent with the 182Hf- 182W metal-silicate segregation age of 2.4 ± 2.0 Ma. These data make the age of Muonionalusta the oldest documented yet for all differentiated bodies in the Solar System and constitute the first high-precision Pb-Pb age determined for crystallization of a phase contained within an iron meteorite group, hence advancing our understanding of early Solar System chronology. Using literature values for the cooling rate, and assuming a closure temperature for Pb of 300 °C, it is further estimated that the IVA parent body accreted within 1 Ma of CAI formation and had cooled to the Pb closure temperature within an additional 1-2 Ma. The overlap between the high-precision Pb-Pb and Hf-W ages points to a small, or rapidly fragmented, planetary body. The isotopic composition of Pb in Gibeon troilite yields a significantly younger age of 4544 ± 7 Ma (MSWD = 1.5), consistent with evidence from the 107Pd- 107Ag chronometer, but we believe this age has been reset by melting upon shock. One puzzling observation is that the apparent 232Th/ 238U of Muonionalusta troilite is particularly low (˜ 0.32), requiring a mechanism capable of

  16. Asteroids and meteorites - Parent bodies and delivered samples

    NASA Technical Reports Server (NTRS)

    Greenberg, R.; Chapman, C. R.

    1983-01-01

    Asteroid physical strengths, which critically affect the quantity of ejecta that can be placed in orbits evolving so as to cross that of the earth, vary widely due to initial composition and size, and subsequent geophysical and collisional evolutions. The meteorite yield on earth additionally depends on meteorite strength, which affects longevity in space and survival through the atmosphere. It is presently shown that meteorites may be primarily derived by cratering rather than disruptive fragmentation, and from large, main-belt asteroids rather than from small, earth-approaching bodies. The model presented combines a variety of evidence from various disciplines to yield results that are consistent with meteorite statistics, although no claim is made for the uniqueness of the model and many of its elements remain uncertain.

  17. Meteorites and their parent planets

    NASA Astrophysics Data System (ADS)

    McSween, Harry Y.

    This book explores the origins of meteorites by tracing them back to their parent bodies, which are the sites of various geological processes. Recent discoveries are reviewed which reveal that the chemical and physical properties of meteorites contain a record of the processes that formed the solar system. How meteorites escape their parent bodies and find their way to earth is explained.

  18. Thermal metamorphism of primitive meteorites. XI - The enstatite meteorites: Origin and evolution of a parent body

    NASA Technical Reports Server (NTRS)

    Biswas, S.; Walsh, T.; Bart, G.; Lipschutz, M. E.

    1980-01-01

    The neutron activation data for Ag, As, Bi, Cd, Co, Cs, Cu, Ga, In, Rb, Se, Te, Tl, and Zn were obtained in samples of Abee heated to 1000-1400 C at low pressures. In addition, these elements were reported in nine enstatite achondrites and in the silicate part of the Mt. Egerton stony-iron. The data show trace element losses above 1000 C by diffusion-controlled processes with apparent activation energies of 8 to 55 kcal/mol; these data together with abundances of aubrites, Mt. Egerton, and E4-6 chondrites, and isotopic results link all enstatite meteorites to a common parent body. The data also indicate that aubrites and the Mt. Egerton material reflect fractional crystallization of a magma produced from enstatite chondrite-like parent material (E6) and the late introduction of chalcophiles and mobile elements transported by an FeS-Fe eutectic from an E4-6 region undergoing open-system metamorphism.

  19. CAIs in CO3 Meteorites: Parent Body or Nebular Alteration?

    NASA Astrophysics Data System (ADS)

    Greenwood, R. C.; Hutchison, R.; Huss, G. R.; Hutcheon, I. D.

    1992-07-01

    It is widely held that alteration of Ca Al-rich inclusions (CAIs) in CV3 and CO3 meteorites occurred in the nebula (Hashimoto 1992). The CO3 chondrites, however, appear to define a metamorphic sequence dominated by parent body, and not nebular, metamorphic effects (Scott and Jones, 1990). To investigate the effects of metamorphism on CAIs we have studied inclusions from 4 CO chondrites: Colony (3.0), Felix (3.2), Lance (3.4), and Warrenton (3.6). In a section of Colony (74 mm^2) 81 CAIs, 30-870 micrometers long, comprise 52 nodular spinel-rich inclusions (fragments of Type-A CAI composed largely of spinel), 12 spinel-pyroxene inclusions, 10 melilite-rich inclusions, 2 hibonite-only inclusions, 2 CaAl4O7-bearing inclusions, and 3 spinel-pyroxene- olivine inclusions. Although a find, CAIs in Colony are relatively fresh, melilite in particular being little altered. In 79% of the spinel-bearing inclusions, spinel has <2wt% FeO, which otherwise ranges to 34.8%. Mg isotopic compositions were determined in 5 selected Colony inclusion; evidence of ^26Mg* from decay of ^26Al was found in 4 CAI. A hibonite-only inclusion has the largest ^26Mg* excess, delta^26Mg 32o/oo. Data show no evidence of isotopic disturbance and define a linear array with slope ^26Mg* /^27Al = (3.4+- 0.6) x 10^-5, like that obtained by Davis and Hinton (1986) in a hibonite-bearing spherule from Ornans. Despite Al/Mg ratios of up to 1500, CaAl4O7 in one inclusion shows no evidence of ^26Mg*; ^26Mg* < 4 x 10^-6. All three melilite-bearing inclusions from Colony C21 (angstrom k(sub)8.3-14.3), C56 (angstrom k(sub)10.5-16) and C62 (angstrom k(sub)15-21) show evidence of radiogenic ^26Mg*. Excess ^26Mg positively correlates with the Al/Mg ratios but the data do not define a unique initial value of ^26Al/^27Al. Data for melilite in C21, in particular, show evidence for disturbance of the Al-Mg system, as is common for Allende CAI (Podosek et al. 1991). Melilites in C56 in contrast show no evidence of

  20. Nature’s Starships. II. Simulating the Synthesis of Amino Acids in Meteorite Parent Bodies

    NASA Astrophysics Data System (ADS)

    Cobb, Alyssa K.; Pudritz, Ralph E.; Pearce, Ben K. D.

    2015-08-01

    Carbonaceous chondrite meteorites are known for having high water and organic material contents, including amino acids. Here we address the origin of amino acids in the warm interiors of their parent bodies (planetesimals) within a few million years of their formation, and we connect this with the astrochemistry of their natal protostellar disks. We compute both the total amino acid abundance pattern and the relative frequencies of amino acids within the CM2 (e.g., Murchison) and CR2 chondrite subclasses based on Strecker reactions within these bodies. We match the relative frequencies to well within an order of magnitude among both CM2 and CR2 meteorites for parent body temperatures <200°C. These temperatures agree with 3D models of young planetesimal interiors. We find theoretical abundances of approximately 7 × 105 parts per billion, which is in agreement with the average observed abundance in CR2 meteorites of (4 ± 7) × 105, but an order of magnitude higher than the average observed abundance in CM2 meteorites of (2 ± 2) × 104. We find that the production of hydroxy acids could be favored over the production of amino acids within certain meteorite parent bodies (e.g., CI1, CM2) but not others (e.g., CR2). This could be due to the relatively lower NH3 abundances within CI1 and CM2 meteorite parent bodies, which leads to less amino acid synthesis. We also find that the water content in planetesimals is likely to be the main cause of variance between carbonaceous chondrites of the same subclass. We propose that amino acid abundances are primarily dependent on the ammonia and water content of planetesimals that are formed in chemically distinct regions within their natal protostellar disks.

  1. Paleo-Magnetic Field Recorded in the Parent Body of the Murchison Meteorite

    NASA Astrophysics Data System (ADS)

    Kletetschka, G.; Páchová, H.

    2014-12-01

    Murchison meteorite is a carbonaceous chondrite containing small amount of chondrules, various inclusions, and matrix with occasional porphyroblasts of olivine and/or pyroxene. We applied magnetic efficiency method (Kletetschka et al 2005, Kohout et al, 2008) in order to get the demagnetization spectra for several randomly oriented fragments of Murchison meteorite. Our method detected not only viscous magnetization removable in low fields, but also very persistent magnetizations in all meterorite fragments. Data suggest that magnetic carriers within the Murchison meteorite were grown in a paleofield of 450 - 850 nT. Meteorite record in other fragments contains an existence of antipodal fields that may be tied to an event of magnetic reversal within the nebular magnetic field or parent asteroid body. Other meteorites show stable record over its entire spectrum, giving magnetic paleofield of 1100 - 1900 nT. Magnetic record in Murchison meteorite comes from magnetite, pyrrhotite and Iron Nickel alloy. Pyrrhotite is suggested to be the main carrier of the paleofield in Murchison. Iron-Nickel alloy generate observable zigzag pattern when magnetically saturated. Kletetschka, G., Kohout, T., Wasilewski, P., and Fuller, M. D., 2005, Recognition of thermal remanent magnetization in rocks and meteorites, The IAGA Scientific Assembly, Volume GAI10: Toulouse, IAGA, p. IAGA2005-A-00945. Kohout, T., Kletetschka, G., Donadini, F., Fuller, M., and Herrero-Bervera, E., 2008, Analysis of the natural remanent magnetization of rocks by measuring the efficiency ratio through alternating field demagnetization spectra: Studia Geophysica Et Geodaetica, v. 52, no. 2, p. 225-235.

  2. Parent Body Influences on Amino Acids in the Tagish Lake Meteorite

    NASA Technical Reports Server (NTRS)

    Glavin, D. P.; Callahan, M. P.; Dworkin, J. P.; Elsila, J. E.; Herd, C. D. K.

    2010-01-01

    The Tagish Lake meteorite is a primitive C2 carbonaceous chondrite with a mineralogy, oxygen isotope, and bulk chemical. However, in contrast to many CI and CM carbonaceous chondrites, the Tagish Lake meteorite was reported to have only trace levels of indigenous amino acids, with evidence for terrestrial L-amino acid contamination from the Tagish Lake meltwater. The lack of indigenous amino acids in Tagish Lake suggested that they were either destroyed during parent body alteration processes and/or the Tagish Lake meteorite originated on a chemically distinct parent body from CI and CM meteorites where formation of amino acids was less favorable. We recently measured the amino acid composition of three different lithologies (11h, 5b, and 11i) of pristine Tagish Lake meteorite fragments that represent a range of progressive aqueous alteration in order 11h < 5b < 11i as inferred from the mineralogy, petrology, bulk isotopes, and insoluble organic matter structure. The distribution and enantiomeric abundances of the one- to six-carbon aliphatic amino acids found in hot-water extracts of the Tagish Lake fragments were determined by ultra performance liquid chromatography fluorescence detection and time of flight mass spectrometry coupled with OPA/NAC derivatization. Stable carbon isotope analyses of the most abundant amino acids in 11h were measured with gas chromatography coupled with quadrupole mass spectrometry and isotope ratio mass spectrometry.

  3. Mineralogy, Petrology, Chronology, and Exposure History of the Chelyabinsk Meteorite and Parent Body

    NASA Technical Reports Server (NTRS)

    Righter, K.; Abell, P.; Agresti, D.; Berger, E. L.; Burton, A. S.; Delaney, J. S.; Fries, M. D.; Gibson, E. K.; Harrington, R.; Herzog, G. F.; Keller, L. P.; Locke, D.; Lindsay, F.; McCoy, T. J.; Morris, R. V.; Nagao, K.; Nakamura-Messenger, K.; Niles, P. B.; Nyquist, L.; Park, J.; Peng, Z. X.; Shih, C. Y.; Simon, J. I.; Swisher, C. C., III; Tappa, M.

    2015-01-01

    The Chelyabinsk meteorite fall on February 15, 2013 attracted much more attention worldwide than do most falls. A consortium led by JSC received 3 masses of Chelyabinsk (Chel-101, -102, -103) that were collected shortly after the fall and handled with care to minimize contamination. Initial studies were reported in 2013; we have studied these samples with a wide range of analytical techniques to better understand the mineralogy, petrology, chronology and exposure history of the Chelyabinsk parent body.

  4. A Petrologic Study of the IAB Iron Meteorites: Constraints on the Formation of the IAB-Winonaite Parent Body

    NASA Technical Reports Server (NTRS)

    Benedix, G. K.; McCoy, T. J.; Keil, K.; Love, S. G.

    1998-01-01

    We have studied IAB iron meteorites and their silicate-bearing inclusions to elucidate the origin of their parent body. We have divided IAB irons into five categories which best describe the inclusions and other properties of the irons.

  5. Electrical conductivity of carbonaceous chondrites and electric heating of meteorite parent bodies

    NASA Technical Reports Server (NTRS)

    Duba, AL

    1987-01-01

    Electromagnetic heating of rock-forming materials most probably was an important process in the early history of the solar system. Electrical conductivity experiments of representative materials such as carbonaceous chondrites are necessary to obtain data for use in electromagnetic heating models. With the assumption that carbon was present at grain boundaries in the material that comprised the meteorite parent bodies, the electrical heating of such bodies was calculated as a function of body size and solar distance using the T-Tauri model of Sonett and Herbert (1977). The results are discussed.

  6. Chronology and Petrology of Silicates From IIE Iron Meteorites: Evidence of a Complex Parent Body Evolution

    NASA Technical Reports Server (NTRS)

    Bogard, Donald D.; Garrison, Daniel H.; McCoy, Timothy J.

    1999-01-01

    IIE iron meteorites contain silicate inclusions whose characteristics suggest a parent body similar to that of H-chondrites. However, these silicates show a wide range of alteration, ranging from Netschadvo and Techado, whose inclusions are little altered. to highly differentiated silicates like-those in Kodaikanal, Weekeroo Station and Colomera, which have lost metal and sulfur and are enriched in feldspar. We find these inclusions to show varying degrees of shock alteration. Because only a limited amount of data on - isotopic ages of HE silicates were available, we made Ar-39 - Ar-40 age determinations of Watson, Techado, miles Colomera, and Sombrerete. Watson has an Ar-Ar age of 3.653 +/- 0.012 Gyr, similar to previously reported ages for Kodaikanal and Netschadvo. We suggest that the various determined radiometric ages of these three meteorites were probably reset by a common impact event. The space exposure ages for these three meteorites are also similar to each other and are considerably younger than exposure ages of other IIEs. Ar-39 - Ar-40 ages inferred for the other four meteorites analyzed are considerably older than Watson and are: Techado =4.49 +/- 0.01 Gyr, Miles =4.412 +/- 0.016 Gyr, Colomera =4.469 +/- 0.012 Gyr, and Sombrerete =4.535 +/- 0.005 Gyr. These ages are in fair agreement with previously reported Rb-Sr isochron ages for Colomera and Weekeroo Station. Although several mechanisms to form HE meteorites previously were suggested, it is not obvious that a single mechanism could produce a suite of meteorites with very different degrees of silicate differentiation and with isotopic ages that differ by >0.8 Gyr. We suggest that those IIEs with older isotopic ages are a product of partial melting and differentiation within the parent body, followed by mixing of silicate and metal while both were relatively hot. Netschadvo and Watson may have formed by this same process or by impact mixing about 4.5 Gyr ago, but their isotopic ages were

  7. Comparison of lunar rocks and meteorites: Implications to histories of the moon and parent meteorite bodies

    NASA Technical Reports Server (NTRS)

    Prinz, M.; Fodor, R. V.; Keil, K.

    1974-01-01

    A number of similarities between lunar and meteoritic rocks are reported and suggest that the comparison is essential for a clear understanding of meteorites as probes of the early history of the solar systems: (1) Monomict and polymict breccias occur in lunar rocks, as well as in achondritic and chondritic meteorites, having resulted from complex and repeated impact processes. (2) Chondrules are present in lunar, as well as in a few achondritic and most chondritic meteorites. It is pointed out that because chondrules may form in several different ways and in different environments, a distinction between the different modes of origin and an estimate of their relative abundance is important if their significance as sources of information on the early history of the solar system is to be clearly understood. (3) Lithic fragments are very useful in attempts to understand the pre- and post-impact history of lunar and meteoritic breccias. They vary from little modified (relative to the apparent original texture), to partly or completely melted and recrystallized lithic fragments.

  8. Comets as parent bodies of CI1 carbonaceous meteorites and possible habitats of ice-microbes

    NASA Astrophysics Data System (ADS)

    Wickramasinghe, N. Chandra; Wickramasinghe, Janaki T.; Wallis, Jamie; Hoover, Richard B.; Rozanov, Alexei Y.

    2011-10-01

    Recent studies of comets and cometary dust have confirmed the presence of biologically relevant organic molecules along with clay minerals and water ice. It is also now well established by deuterium/hydrogen ratios that the CI1 carbonaceous meteorites contain indigenous extraterrestrial water. The evidence of extensive aqueous alteration of the minerals in these meteorites led to the hypothesis that water-bearing asteroids or comets represent the parent bodies of the CI1 (and perhaps CM2) carbonaceous meteorites. These meteorites have also been shown to possess a diverse array of complex organics and chiral and morphological biomarkers. Stable isotope studies by numerous independent investigators have conclusively established that the complex organics found in these meteorites are both indigenous and extraterrestrial in nature. Although the origin of these organics is still unknown, some researchers have suggested that they originated by unknown abiotic mechanisms and may have played a role in the delivery of chiral biomolecules and the origin of life on Early Earth. In this paper we review these results and investigate the thermal history of comets. We show that permanent as well as transient domains of liquid water can be maintained on a comet under a plausible set of assumptions. With each perihelion passage of a comet volatiles are preferentially released, and during millions of such passages the comet could shed crustal debris that may survive transit through the Earth's atmosphere as a carbonaceous meteorite. We review the current state of knowledge of comets and carbonaceous meteorites. We also present the results of recent studies on the long-term viability of terrestrial ice-microbiota encased in ancient glacial ice and permafrost. We suggest that the conditions which have been observed to prevail on many comets do not preclude either survivability (or even the active metabolism and growth) of many types of eukaryotic and prokaryotic microbial

  9. Comets as Parent Bodies of CI1 Carbonaceous Meteorites and Possible Habitats of Ice-Microbiota

    NASA Technical Reports Server (NTRS)

    Wickramasinghe, N. Chandra; Wallis, Daryl H.; Rozanov, Alexei Yu.; Hoover, Richard B.

    2011-01-01

    Recent studies of comets and cometary dust have confirmed the presence of biologically relevant organic molecules along with clay minerals and water ice. It is also now well established by deuterium/hydrogen ratios that the CI1 carbonaceous meteorites contain indigenous extraterrestrial water. The evidence of extensive aqueous alteration of the minerals in these meteorites led to the hypothesis that water-bearing asteroids or comets represent the parent bodies of the CI1 (and perhaps CM2) carbonaceous meteorites. These meteorites have also been shown to possess a diverse array of complex organics and chiral and morphological biomarkers. Stable isotope studies by numerous independent investigators have conclusively established that the complex organics found in these meteorites are both indigenous and extraterrestrial in nature. Although the origin of these organics is still unknown, some researchers have suggested that they originated by unknown abiotic mechanisms and may have played a role in the delivery of chiral biomolecules and the origin of life on Early Earth. In this paper we review these results and investigate the thermal history of comets. We show that permanent as well as transient domains of liquid water can be maintained on a comet under a plausible set of assumptions. With each perihelion passage of a comet volatiles are preferentially released, and during millions of such passages the comet could shed crustal debris that may survive transit through the Earth s atmosphere as a carbonaceous meteorite. We review the current state of knowledge of comets and carbonaceous meteorites. We also present the results of recent studies on the long-term viability of terrestrial ice-microbiota encased in ancient glacial ice and permafrost. We suggest that the conditions which have been observed to prevail on many comets do not preclude either survivability (or even the active metabolism and growth) of many types of eukaryotic and prokaryotic microbial

  10. Petrogenesis of the Elephant Moraine A79001 meteorite Multiple magma pulses on the shergottite parent body

    NASA Technical Reports Server (NTRS)

    Mcsween, H. Y., Jr.; Jarosewich, E.

    1983-01-01

    The EETA 79001 achondrite consists of two distinct igneous lithologies joined along a planar, non-brecciated contact. Both are basaltic rocks composed primarily of pigeonite, augite, and maskelynite, but one contains zoned megacrysts of olivine, orthopyroxene, and chromite that represent disaggregated xenoliths of harzburzite. Both lithologies probably formed from successive volcanic flows or multiple injections of magma into a small, shallow chamber. Many similarities between the two virtually synchronous magmas suggest that they are related. Possible mechanisms to explain their differences involve varying degrees of assimilation, fractionation from similar parental magmas, or partial melting of a similar source peridotite; of these, assimilation of the observed megacryst assemblage seems most plausible. However, some isotopic contamination may be required in any of these petrogenetic models. The meteorite has suffered extensive shock metamorphism and localized melting during a large impact event that probably excavated and liberated it from its parent body.

  11. Composition of Chelyabinsk Meteorite: Identifying its Parent Body in the Main Belt

    NASA Astrophysics Data System (ADS)

    Reddy, Vishnu; Cloutis, E.; Cuddy, M.; Bottke, W.; Sanchez, J.; Mann, P.; Izawa, M.; Fujihara, G.; Gaffey, M.; Le Corre, L.

    2013-10-01

    On February 15, 2013 a colossal fireball was observed over the Chelyabisnk region of Russia, which caused widespread damage across the region (Brown 2013). Subsequently, thousands of stones rained on villages south of Chelyabinsk. Here we report near-IR spectra properties of the Chelyabinsk meteorite samples in an effort to identify its parent body in the main belt. Chelyabinsk is an LL5 ordinary chondrite with olivine and pyroxene as major mineral phases. Our samples also included a dark-colored fine grain impact melt component, which is a significant portion (1/3rd) of the meteorite apart from light-colored lithology typical of ordinary chondrites (2/3rd) (Vernad, 2013). Laboratory measurements suggest an olivine composition of Fa28 (mol. %) and pyroxene composition of Fs23 (mol. %). Spectrally derived olivine and pyroxene composition using equations from Dunn et al. (2010) are Fa25+/-1.3 and Fs21+/-1.4, respectively. While spectrally derived values are lower than those directly measured from the samples (possibly due to compositional heterogeneity), they are consistent with LL chondrites, which have an olivine and pyroxene composition of Fa26-31 and Fs22-26. The impact melt component is spectrally distinct from the light-color lithology with lower albedo 9% vs. 32% at 0.55 microns), weaker absorption band I depth (4% vs. 30%) and steeper spectral slope. Works of Vernazza et al. (2008) and Dunn et al. (2013) have shown that a majority of the NEAs 60%) have an LL chondrite type composition. Dynamical modeling (Bottke et al. 2002) has shown that these LL chondrite NEAs are preferentially derived (83 percent) from the nu6 resonance (Dunn et al. 2013). The Flora family, which lies near the nu6 resonance, is dominated by S-type asteroids and has been hypothesized as the primary source region for LL chondrite meteorites and NEAs. Our spectrally derived olivine and pyroxene composition for Flora (Fa29+/-1.3 and Fs24+/-1.4) is consistent with Chelyabinsk (Fa28 and Fs23

  12. Jadeite in Chelyabinsk meteorite and the nature of an impact event on its parent body.

    PubMed

    Ozawa, Shin; Miyahara, Masaaki; Ohtani, Eiji; Koroleva, Olga N; Ito, Yoshinori; Litasov, Konstantin D; Pokhilenko, Nikolay P

    2014-01-01

    The Chelyabinsk asteroid impact is the second largest asteroid airburst in our recorded history. To prepare for a potential threat from asteroid impacts, it is important to understand the nature and formational history of Near-Earth Objects (NEOs) like Chelyabinsk asteroid. In orbital evolution of an asteroid, collision with other asteroids is a key process. Here, we show the existence of a high-pressure mineral jadeite in shock-melt veins of Chelyabinsk meteorite. Based on the mineral assemblage and calculated solidification time of the shock-melt veins, the equilibrium shock pressure and its duration were estimated to be at least 3-12 GPa and longer than 70 ms, respectively. This suggests that an impactor larger than 0.15-0.19 km in diameter collided with the Chelyabinsk parent body at a speed of at least 0.4-1.5 km/s. This impact might have separated the Chelyabinsk asteroid from its parent body and delivered it to the Earth. PMID:24852082

  13. Jadeite in Chelyabinsk meteorite and the nature of an impact event on its parent body

    PubMed Central

    Ozawa, Shin; Miyahara, Masaaki; Ohtani, Eiji; Koroleva, Olga N.; Ito, Yoshinori; Litasov, Konstantin D.; Pokhilenko, Nikolay P.

    2014-01-01

    The Chelyabinsk asteroid impact is the second largest asteroid airburst in our recorded history. To prepare for a potential threat from asteroid impacts, it is important to understand the nature and formational history of Near-Earth Objects (NEOs) like Chelyabinsk asteroid. In orbital evolution of an asteroid, collision with other asteroids is a key process. Here, we show the existence of a high-pressure mineral jadeite in shock-melt veins of Chelyabinsk meteorite. Based on the mineral assemblage and calculated solidification time of the shock-melt veins, the equilibrium shock pressure and its duration were estimated to be at least 3–12 GPa and longer than 70 ms, respectively. This suggests that an impactor larger than 0.15–0.19 km in diameter collided with the Chelyabinsk parent body at a speed of at least 0.4–1.5 km/s. This impact might have separated the Chelyabinsk asteroid from its parent body and delivered it to the Earth. PMID:24852082

  14. Jadeite in Chelyabinsk meteorite and the nature of an impact event on its parent body.

    PubMed

    Ozawa, Shin; Miyahara, Masaaki; Ohtani, Eiji; Koroleva, Olga N; Ito, Yoshinori; Litasov, Konstantin D; Pokhilenko, Nikolay P

    2014-01-01

    The Chelyabinsk asteroid impact is the second largest asteroid airburst in our recorded history. To prepare for a potential threat from asteroid impacts, it is important to understand the nature and formational history of Near-Earth Objects (NEOs) like Chelyabinsk asteroid. In orbital evolution of an asteroid, collision with other asteroids is a key process. Here, we show the existence of a high-pressure mineral jadeite in shock-melt veins of Chelyabinsk meteorite. Based on the mineral assemblage and calculated solidification time of the shock-melt veins, the equilibrium shock pressure and its duration were estimated to be at least 3-12 GPa and longer than 70 ms, respectively. This suggests that an impactor larger than 0.15-0.19 km in diameter collided with the Chelyabinsk parent body at a speed of at least 0.4-1.5 km/s. This impact might have separated the Chelyabinsk asteroid from its parent body and delivered it to the Earth.

  15. Enrichment of the Amino Acid L-Isovaline by Aqueous Alteration on CI and CM Meteorite Parent Bodies

    NASA Technical Reports Server (NTRS)

    Glavin, Daniel P.; Dworkin, Jason P.

    2009-01-01

    The distribution and enantiomeric composition of the 5-carbon (C(sub 5)) amino acids found in Cl-, CM-, and CR-type carbonaceous meteorites were investigated by using liquid chromatography fluorescence detection/TOF-MS coupled with o-phthaldialdehyde/Nacetyl- l-cysteine derivatization. A large L-enantiomeric excess (ee) of the a-methyl amino acid isovaline was found in the CM meteorite Murchison (L(sub ee) = 18.5 +/- 2.6%) and the Cl meteorite Orguell (L(sub ee) = 15.2 +/- 4.0%). The measured value for Murchison is the largest enantiomeric excess in any meteorite reported to date, and the Orgueil measurement of an isovaline excess has not been reported previously for this or any Cl meteorite. The L-isovaline enrichments in these two carbonaceous meteorites cannot be the result of interference from other C(sub 5) amino acid isomers present in the samples, analytical biases, or terrestrial amino acid contamination. We observed no L-isovaline enrichment for the most primitive unaltered Antarctic CR meteorites EET 92042 and QUE 99177. These results are inconsistent with UV circularly polarized light as the primary mechanism for L-isovaline enrichment and indicate that amplification of a small initial isovaline asymmetry in Murchison and Orgueil occurred during an extended aqueous alteration phase on the meteorite parent bodies. The large asymmetry in isovaline and other alpha-dialkyl amino acids found in altered Ct and CM meteorites suggests that amino acids delivered by asteroids, comets, and their fragments would have biased the Earth's prebiotic organic inventory with left-handed molecules before the origin of life.

  16. Chemical systematics of the Shergotty meteorite and the composition of its parent body (Mars)

    NASA Technical Reports Server (NTRS)

    Laul, J. C.; Smith, M. R.; Waenke, H.; Jagoutz, E.; Dreibus, G.

    1986-01-01

    Sixty elements in two bulk samples of Shergotty meteorite and 30 elements in various mineral separates of Shergotty were identified, using mainly INAA and RNAA techniques. In addition, elements leached out from powdered samples of Shergotty and EETA 79001 meteorites by 0.1 N HCl, as well as the elements of their residues, were analyzed. The results have indicated that Shergotty meteorite is homogeneous in its major element composition, but heterogeneous with respect to large-ion lithophile elements, such as K, Ba, Sr, Zr, Hf, Ta, Th, and rare-earth elements (REEs). It is even more heterogeneous with respect to volatile elements, such as Cd, Te, Tl, and Bi, and the siderophiles Au and Ag. The REE patterns of the Shergotty and EETA 79001 residues are identical, indicating that the parent magmas of both meteorites are compositionally similar. However, their leachate (phosphate) patterns are different, suggesting two components for the Shergotty, one of which is similar to the EETA 79001 leachate.

  17. Products of the Strecker Synthesis as Indicators of Parent Body Conditions of the Murchison Meteorite

    NASA Technical Reports Server (NTRS)

    Lerner, Narcinda R.; Cooper, George W.; Chang, Sherwood (Technical Monitor)

    1996-01-01

    The Strecker synthesis, R2C=O + HCN + NH3 yields R2C(NH2)CN + H2O yields R2C(NH2)CO2H has been proposed as a source of amino acids in meteorites. The detection of carbonlyl compounds, the precursors of the amino acids in the Strecker synthesis, and a-hydroxy acids, important by-products of the Strecker synthesis, in the Murchison meteorite supports this conjecture. However, the following observations raise questions about the Strecker synthesis as the source of a-amino and a-hydroxy acids in Murchison: a) Imino acetic acids are also important by-products of the Strecker synthesis and have not been reported in Murchison. b) a-aminisobutyric acid (AIBA) is one of the most abundant amino acids in Murchison but the Strecker synthesis conducted at room temperature produced only small amounts of AIBA relative to other amino acids. c) If the a-amino and a-hydroxy acids observed in Murchison arose from a common precursor this ought to be reflected in their relative abundances, but the straight chain a-hydroxy acids appeared to be relatively abundant compared with the analogous a-amino acids. In order to address question a) we have examined a non-hydrolyzed aqueous extract of the Murchison meteorite. Imino di acetic acid, Imino propionic acetic acid and Imino butyric acetic acid (both isomers) have been identified in this fraction. The relative abundances of amino acids and imino acetic acids in this fraction are consistent with a Strecker synthesis at low temperature (263 K) as a origin of both the amino acids and the imino acetic acids found on Murchison. To deal with questions b) and c) we have carried out laboratory simulations of the Strecker synthesis. The starting concentrations for carbonlyl compounds used were based on estimates of what these concentrations might have been on the parent body. for the carbonyl compounds this estimate was determined by the amount of carbonyl compound found on Murchison plus the amounts of the corresponding amino acid and hydroxy acid

  18. Mineralogy, petrology, chronology, and exposure history of the Chelyabinsk meteorite and parent body

    NASA Astrophysics Data System (ADS)

    Righter, K.; Abell, P.; Agresti, D.; Berger, E. L.; Burton, A. S.; Delaney, J. S.; Fries, M. D.; Gibson, E. K.; Haba, M. K.; Harrington, R.; Herzog, G. F.; Keller, L. P.; Locke, D.; Lindsay, F. N.; McCoy, T. J.; Morris, R. V.; Nagao, K.; Nakamura-Messenger, K.; Niles, P. B.; Nyquist, L. E.; Park, J.; Peng, Z. X.; Shih, C.-Y.; Simon, J. I.; Swisher, C. C.; Tappa, M. J.; Turrin, B. D.; Zeigler, R. A.

    2015-10-01

    Three masses of the Chelyabinsk meteorite have been studied with a wide range of analytical techniques to understand the mineralogical variation and thermal history of the Chelyabinsk parent body. The samples exhibit little to no postentry oxidation via Mössbauer and Raman spectroscopy indicating their fresh character, but despite the rapid collection and care of handling some low levels of terrestrial contamination did nonetheless result. Detailed studies show three distinct lithologies, indicative of a genomict breccia. A light-colored lithology is LL5 material that has experienced thermal metamorphism and subsequent shock at levels near S4. The second lithology is a shock-darkened LL5 material in which the darkening is caused by melt and metal-troilite veins along grain boundaries. The third lithology is an impact melt breccia that formed at high temperatures (~1600 °C), and it experienced rapid cooling and degassing of S2 gas. Portions of light and dark lithologies from Chel-101, and the impact melt breccias (Chel-102 and Chel-103) were prepared and analyzed for Rb-Sr, Sm-Nd, and Ar-Ar dating. When combined with results from other studies and chronometers, at least eight impact events (e.g., ~4.53 Ga, ~4.45 Ga, ~3.73 Ga, ~2.81 Ga, ~1.46 Ga, ~852 Ma, ~312 Ma, and ~27 Ma) are clearly identified for Chelyabinsk, indicating a complex history of impacts and heating events. Finally, noble gases yield young cosmic ray exposure ages, near 1 Ma. These young ages, together with the absence of measurable cosmogenic derived Sm and Cr, indicate that Chelyabinsk may have been derived from a recent breakup event on an NEO of LL chondrite composition.

  19. Maskelynite in asteroidal, lunar and planetary basaltic meteorites: An indicator of shock pressure during impact ejection from their parent bodies

    NASA Astrophysics Data System (ADS)

    Rubin, Alan E.

    2015-09-01

    Maskelynite is a diaplectic glass that forms from plagioclase at shock pressures of ∼20-30 GPa, depending on the Ca concentration. The proportion of maskelynite-rich samples in a basaltic meteorite group correlates with the parent-body escape velocity and serves as a shock indicator of launching conditions. For eucrites (basalts widely presumed to be from Vesta; vesc = 0.36 km s-1), ∼5% of the samples are maskelynite rich. For the Moon (vesc = 2.38 km s-1), ∼30% of basaltic meteorites are maskelynite rich. For Mars (vesc = 5.03 km s-1), ∼93% of basaltic meteorites are maskelynite rich. In contrast, literature data show that maskelynite is rare (∼1%) among mare basalts and basaltic fragments in Apollo 11, 12, 15 and 17 soils (which were never ejected from the Moon). Angrites are unbrecciated basaltic meteorites that are maskelynite free; they were ejected at low-to-moderate shock pressures from an asteroid smaller than Vesta. Because most impacts that eject materials from a large (⩾100 km) parent body are barely energetic enough to do that, a collision that has little more than the threshold energy required to eject a sample from Vesta will not be able to eject identical samples from the Moon or Mars. There must have been relatively few impacts, if any, that launched eucrites off their parent body that also imparted shock pressures of ∼20-30 GPa in the ejected rocks. More-energetic impacts were required to launch basalts off the Moon and Mars. On average, Vesta ejecta were subjected to lower shock pressures than lunar ejecta, and lunar ejecta were subjected to lower shock pressures than martian ejecta. H and LL ordinary chondrites have low percentages of shock-stage S5 maskelynite-bearing samples (∼1% and ∼4%, respectively), probably reflecting shock processes experienced by these rocks on their parent asteroids. In contrast, L chondrites have a relatively high proportion of samples containing maskelynite (∼11%), most likely a result of

  20. Variability, absorption features, and parent body searches in "spectrally featureless" meteorite reflectance spectra: Case study - Tagish Lake

    NASA Astrophysics Data System (ADS)

    Izawa, M. R. M.; Craig, M. A.; Applin, D. M.; Sanchez, J. A.; Reddy, V.; Le Corre, L.; Mann, P.; Cloutis, E. A.

    2015-07-01

    Reflectance spectra of many asteroids and other Solar System bodies are commonly reported as "featureless". Here, we show that weak but consistently detectable absorption bands are observable in 200-2500 nm spectra of the Tagish Lake meteorite, a likely compositional and spectral analogue for low-albedo, "spectrally-featureless" asteroids. Tagish Lake presents a rare opportunity to study multiple lithologies within a single meteorite. Reflectance spectra of Tagish Lake display significant variation between different lithologies. The spectral variations are due in part to mineralogical variations between different Tagish Lake lithologies. Ultraviolet reflectance spectra (200-400 nm), few of which have been reported in the literature to date, reveal albedo and spectral ratio variations as a function of mineralogy. Similarly visible-near infrared reflectance spectra reveal variations in albedo, spectral slope, and the presence of weak absorption features that persist across different lithologies and can be attributed to various phases present in Tagish Lake. These observations demonstrate that significant spectral variability may exist between different lithologies of Tagish Lake, which may affect the interpretation of potential source body spectra. It is also important to consider the spectral variability within the meteorite before excluding compositional links between possible parent bodies in the main belt and Tagish Lake. Tagish Lake materials may also be spectral-compositional analogues for materials on the surfaces of other dark asteroids, including some that are targets of upcoming spacecraft missions. Tagish Lake has been proposed as a spectral match for 'ultra-primitive' D or P-type asteroids, and the variability reported here may be reflected in spatially or rotationally-resolved spectra of possible Tagish Lake parent bodies and source objects in the Near-Earth Asteroid population. A search for objects with spectra similar to Tagish Lake has been carried

  1. Deuterium Enrichment of Amino and Hydroxy Acids Found in the Murchison Meteorite: Constraints on Parent Body Conditions

    NASA Technical Reports Server (NTRS)

    Lerner, Narcinda R.; Chang, Sherwood (Technical Monitor)

    1997-01-01

    The alpha-amino and alpha-hydroxy acids found in the Murchison carbonaceous chondrite are deuterium enriched. These compounds are thought to have originated from common deuterium enriched carbonyl precursors, by way of a Strecker synthesis which took place in a solution of HCN, NH3, and carbonyl compounds during the period of aqueous alteration of the meteorite parent body. However, the hydroxy acids found on Murchison are less deuterium enriched than the amino acids. With the objective of determining if the discrepancy in deuterium enrichment between the amino acids and the hydroxy acids found on Murchison is consistent with their formation in a Strecker synthesis, we have measured the deuterium content of alpha-amino and alpha-hydroxy acids produced in solutions of deuterated carbonyl compounds, KCN and NH4Cl, and also in mixtures of such solutions and Allende dust at 263 K and 295 K. Retention of the isotopic signature of the starting carbonyl by both alpha amino acids and alpha hydroxy acids is more dependent upon temperature, concentration and pH than upon the presence of meteorite dust in the solution. The constraints these observations place on Murchison parent body conditions will be discussed.

  2. High-precision sulfur isotope composition of enstatite meteorites and implications of the formation and evolution of their parent bodies

    NASA Astrophysics Data System (ADS)

    Defouilloy, C.; Cartigny, P.; Assayag, N.; Moynier, F.; Barrat, J.-A.

    2016-01-01

    In order to better understand the formation and evolution of their parent bodies, the three isotope ratios of sulfur were analyzed in 33 enstatite meteorites (24 enstatite chondrites and 9 aubrites). The results show that on average all enstatite chondrite groups are enriched in the lightest isotopes compared to other chondrite groups, with means of δ34S of -0.28 ± 0.22‰ for EH3/4, -0.16 ± 0.16‰ for EH5, -0.32 ± 0.15‰ for EL3, -0.67 ± 0.16‰ for EL6 and -0.64 ± 0.00‰ for EL7 (all 1σ). Aubrites show a larger isotope variability in their composition, with a δ34S varying from -1.350‰ to +0.154‰. Contrary to previously published results, our data show a distinct composition for EL6 compared to other enstatite chondrites. This could be related to an impact-induced loss of isotopically heavy oldhamite (δ34S = by 3.62 ± 3.02‰ (1σ)) on the EL parent body. Although the bulk sulfur in both enstatite meteorites and aubrites does not show any significant Δ33S and Δ36S, the oldhamite fraction shows clear evidence of mass independent fractionation on the 36S/32S ratio (in 3 out of 9 analyzes, Δ36S up to +2.2‰), a signal that is not correlated to any 33S/32S anomaly (in 1 out of 9 analyzes, Δ33S down to -0.085‰). Though a nebular or photochemical origin cannot be ruled out, the most plausible mechanism to produce such isolated non-mass dependent 36S/32S anomalies would be a contribution of FeCl2 containing excesses of 36S due to the decay of 36Cl to the leached oldhamite fraction. Even though the sulfur isotopic composition measured in enstatite meteorites is distinct from the Bulk Silicate Earth (BSE), the isotopically lightest samples of EL6, EL7 and aubrites are approaching the isotopic composition of the BSE and enstatite meteorites remain the meteorites with the sulfur isotopic composition the closest to the terrestrial one.

  3. Electrochemical measurements and thermodynamic calculations of redox equilibria in pallasite meteorites - Implications for the eucrite parent body

    NASA Technical Reports Server (NTRS)

    Righter, Kevin; Arculus, Richard J.; Paslick, Cassi; Delano, John W.

    1990-01-01

    The intrinsic oxygen fugacity (IOF) of olivine separates from the Salta, Springwater, and Eagle Station pallasites was measured between 850 and 1150 C using oxygen-specific solid zirconia electrolytes at 100,000 Pa. Thermodynamic calculations of redox equilibria involving equalibrium pallasite assemblages are in good agreement with the experimental results and provide a lower limit to pallasite redox stability; others involving disequilibrium assemblages, suggest that pallasites experienced localized, late-stage oxidation and reduction effects. Consideration of the redox buffer metal-olivine-orthopyroxene utilizing calculated Eucrite Parent Body (EPB) mantle phase compositions indicates that small redox gradients may have existed in the EPB. Such gradients may have produced strong compositional variation within the EPB. In addition, there is apparently significant redox heterogeneity in the source area of Eagle Station Trio pallasites and Bocaiuva iron meteorites.

  4. Intrinsic oxygen fugacity measurements on seven chondrites, a pallasite, and a tektite and the redox state of meteorite parent bodies

    USGS Publications Warehouse

    Brett, R.; Sato, M.

    1984-01-01

    Intrinsic oxygen-fugacity (fO2) measurements were made on five ordinary chondrites, a carbonaceous chondrite, an enstatite chondrite, a pallasite, and a tektite. Results are of the form of linear log fO2 - 1 T plots. Except for the enstatite chondrite, measured results agree well with calculated estimates by others. The tektite produced fO2 values well below the range measured for terrestrial and lunar rocks. The lowpressure atmospheric regime that is reported to follow large terrestrial explosions, coupled with a very high temperature, could produce glass with fO2 in the range measured. The meteorite Salta (pallasite) has low fO2 and lies close to Hvittis (E6). Unlike the other samples, results for Salta do not parallel the iron-wu??stite buffer, but are close to the fayalite-quartz-iron buffer in slope. Minor reduction by graphite appears to have taken place during metamorphism of ordinary chondrites. fO2 values of unequilibrated chondrites show large scatter during early heating suggesting that the constituent phases were exposed to a range of fO2 conditions. The samples equilibrated with respect to fO2 in relatively short time on heating. Equilibration with respect to fO2 in ordinary chondrites takes place between grades 3 and 4 of metamorphism. Application of P - T - fO2 relations in the system C-CO-CO2 indicates that the ordinary chondrites were metamorphosed at pressures of 3-20 bars, as it appears that they lay on the graphite surface. A steep positive thermal gradient in a meteorite parent body lying at the graphite surface will produce thin reduced exterior, an oxidized near-surface layer, and an interior that is increasingly reduced with depth; a shallow thermal gradient will produce the reverse. A body heated by accretion on the outside will have a reduced exterior and oxidized interior. Meteorites from the same parent body clearly are not required to have similar redox states. ?? 1984.

  5. Cooling rates and parent bodies of iron meteorites from group IIICD, IAB, and IVB

    NASA Astrophysics Data System (ADS)

    Rasumssen, K. L.

    1989-03-01

    Metallographic cooling rates for the iron meteorites Carlton (IIICD), Toluca (IAB), and Odessa (IAB) are calculated using the central Ni concentration versus taenite width method. For members of group IVB, the ungrouped iron meteorite Chinga, and the high-Ni members of IIICD and IAB, kamacite bandwidth cooling rates are determined. The cooling rates are up to several orders of magnitude faster than those from previous calculations.

  6. Composition of solar flare noble gases preserved in meteorite parent body regolith

    NASA Technical Reports Server (NTRS)

    Rao, M. N.; Garrison, D. H.; Bogard, D. D.; Badhwar, G.; Murali, A. V.

    1991-01-01

    Isotopic composition of solar-flare (SF) Ne was determined in acid-etched pyroxene mineral separates from the Kapoeta meteorite, a brecciated meteorite known to contain implanted solar gases. The results yield the SF Ne-20/Ne-22 ratio of 11.6 +/-0.2, confirming previous determinations of this SF ratio in lunar and meteoritic samples. The same SF Ne composition was also obtained by applying an ordinate intercept technique to the same data set. The ordinate intercept technique was then applied to the Ar and He data. The results are SF Ar-36/Ar-38 = 4.9 +/-0.1 and SF He-4/He-3 = 3800 +/-200. These values are significantly different from the solar-wind (SW) Ar and He values. It is estimated that the concentration of the SF component in Kapoeta pyroxenes is about 20 percent that of the SW component, orders of magnitude higher than expected from SW and SF proton flux measurements.

  7. Early impact event and fluid activity on H chondrite parent body registered in the Pułtusk meteorite

    NASA Astrophysics Data System (ADS)

    Krzesinska, Agata

    2015-04-01

    Impact is one of the most important processes affecting asteroids, but it is neglected as a source for heat of these bodies. Recent modeling work show, however, that impact into warm planetesimals is able to cause global-scale temperature increase to the point of melting of silicates [1]. An obvious consequence of this fact is that the impact activity in early evolution of asteroids may promote formation of melt and its differentiation. H chondrites provide some lines of evidence for an early, 4.4 Ga impact event on their parent body. The event resulted in formation of heavily shocked and melted H chondrites with old gas retention ages [2, 3], including Portales Valley, an unique metal-rich breccia [e.g. 4]. The impact led also, very likely, to unmixing of silicate and metal-sulfide melts and to formation of silicate-iron non-magmatic IIE meteorites [5]. Additional evidence for this event, and for melting it caused, may come from highly equilibrated and recrystallized fragments of the Pułtusk meteorite containing vein-like metal accumulations [6]. In the Pułtusk, vein-like metal accumulations are kamacite-rich, and basically depleted in sulfides. They form many tendrils into the equilibrated, well recrystallized chondritic rock. Marked feature of the chondritic rock at the contact with accumulations is presence of unusually large phosphate and feldspar grains. The minerals bear record of crystallization from melt. Both vein-like metal accumulations and chondritic rock record, however, slow cooling rate. Phopshates are in the meteorite represented by merrillite and apatite, predominantly intergrown with each other. Merrillite poikilitically encloses silicate grains. It is probably of magmatic origin, since it contains detectable amount of potassium and high content of sodium. Apatite contains varying concentrations of chlorine, fluorine and missing structural component. Content of Cl and F are negatively correlated and both elements are heterogeneously distributed

  8. The IVA Parent Body: Evidence from Silicate-Bearing Group IVA Iron Meteorites

    NASA Astrophysics Data System (ADS)

    Ulff-Moller, F.; Kallemeyn, G. W.; Rasmussen, K. L.

    1992-07-01

    The IVA iron meteorites Steinbach (SB), Sao Joao Nepomuceno (SJN), Gibeon and Bishop Canyon are unusual in their contents of silicates. SB is particularly rich in silicates (ca. 50 wt%) and was long classified as a stony iron (Dorfler et al., 1965) but the metal fraction is typical of group IVA iron meteorites (Schaudy et al., 1972). The SB and SJN contain low-Ca pyroxene and tridymite in roughly equal proportions, whereas only tridymite is found in the two other meteorites. Reid et al. (1974) found that coexisting orthopyroxene and clinopyroxenes in SB (En 85) were formed in a narrow two-phase field at 1200 degrees C and preserved by comparatively rapid cooling. We present cooling rate estimates as well as minor element data for the silicates obtained by electron microprobe and trace elements (REE and siderophiles) for the bulk silicate fraction by INAA. The coarse granular texture of the silicates and the presence of finely dispersed sulfide inclusions in the pyroxenes might suggest a cumulate origin, but the high proportion of tridymite combined with MgO-rich pyroxene is unusual if a chondritic magma is assumed. One way of forming excess tridymite is by extreme reduction of a pallasite-type metal/olivine mixture. Our INAA data on SB bulk silicates show a pattern of REE and Sc, Cr, and Mn, which is qualitatively consistent with orthopyroxene that crystallized from a moderately evolved magma with chondritic REE levels. The incompatible elements (including Cr!) in SB pyroxene are correlated and vary up to a factor of 5 (eg., Ti and Al), whereas Ca shows a bimodal variation corresponding roughly to the coexisting orthopyroxene and clinopyroxene. The minor element variations in SB pyroxene thus resemble magmatic zoning. The SJN pyroxene is marginally more MgO-rich (En 86) and shows a similar bimodal Ca distribution although it is possibly one phase. If correct, this suggests slower cooling at a higher temperature than SB. References: Dorfler G., Hecht F. and

  9. Electrical conductivity of carbonaceous chondrites and electric heating of meteorite parent bodies

    NASA Technical Reports Server (NTRS)

    Duba, A.

    1986-01-01

    The electrical conductivity of samples of the Murchison and Allende carbonaceous chondrites is 4 to 6 magnitudes greater than rock forming minerals such as Olivine up to 700 C. The remarkably high electrical conductivity of these meteorites is attributed to carbon at grain boundaries. The environment in the wake of the space station can be exploited to produce conditions which will allow pyrolysis of carbonaceous chondrites. An experimental package consisting of a one square meter shield attached to a 15 cm diameter by 40 cm long furnace and tied to a conductance bridge, furnace controller, and digital voltmeter inside the space station via umbilical cable could make the required measurements. Since heating rates as low as 0.1 C/hour are required to study kinetics of the pyrolysis reations which are the cause of the high conductivity of the carbonaceous chondrites, experimental times up to 3 months will be needed.

  10. Copper stable isotopes as tracers of metal-sulphide segregation and fractional crystallisation processes on iron meteorite parent bodies

    NASA Astrophysics Data System (ADS)

    Williams, Helen M.; Archer, Corey

    2011-06-01

    lowest Δ 65Cu M-FeS values, whereas the converse is observed in the irons with large values D Cu that deviate most from Cu concentration equilibrium. The magnitudes of Cu and Fe isotope fractionation between metal and FeS in the most equilibrated samples are similar: 0.25 and 0.32‰/amu, respectively. As proposed in an earlier study ( Williams et al., 2006) the range in Δ 57Fe M-FeS values can be explained by incomplete Fe isotope equilibrium between metal and sulphide during cooling, where the most rapidly-cooled samples are furthest from isotopic equilibrium and display the smallest Δ 57Fe M-FeS and largest D Cu values. The range in Δ 65Cu M-FeS, however, reflects the combined effects of partial isotopic equilibrium overprinting an initial kinetic signature produced by the diffusion of Cu from metal into exsolving sulphides and the faster diffusion of the lighter isotope. In this scenario, newly-exsolved sulphides initially have low Cu contents (i.e. high D Cu) and extremely light δ 65Cu FeS values; with progressive equilibrium and fractional crystallisation the Cu contents of the sulphides increase as their isotopic composition becomes less extreme and closer to the metal value. The correlation between Δ 65Cu M-FeS and Δ 57Fe M-FeS is therefore a product of the superimposed effects of kinetic fractionation of Cu and incomplete equilibrium between metal and sulphide for both isotope systems during cooling. The correlations between Δ 65Cu M-FeS and Δ 57Fe M-FeS are defined by both magmatic and non-magmatic irons record fractional crystallisation and cooling of metallic melts on their respective parent bodies as sulphur and chalcophile elements become excluded from crystallised solid iron and concentrated in the residual melt. Fractional crystallisation processes at shallow levels have been implicated in the two main classes of models for the origin of the non-magmatic iron meteorites; at (i) shallow levels in impact melt models and (ii) at much deeper levels

  11. The Halite-Bearing Zag and Monahans (1998) Meteorite Breccias: Shock Metamorphism, Thermal Metamorphism and Aqueous Alteration on the H-Chondrite Parent Body

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.; Zolensky, Michael E.; Bodnar, Robert J.

    2002-01-01

    Zag and Monahans (1998) are H-chondrite regolith breccias comprised mainly of lightcolored metamorphosed clasts, dark clasts that exhibit extensive silicate darkening, and a halite-bearing clastic matrix. These meteorites reflect a complex set of modification processes that occurred on the H-chondrite parent body. The light-colored clasts are thermally metamorphosed H5 and H6 rocks that were fragmented and deposited in the regolith. The dark clasts formed from light-colored clasts during shock events that melted and mobilized a significant fraction of their metallic Fe-Ni and troilite grains. The clastic matrices of these meteorites are rich in solar-wind gases. Parent-body water was required to cause leaching of chondri tic minerals and chondrule glass; the fluids became enriched in Na, K, CI, Br, AI, Ca, Mg and Fe. Evaporation of the fluids caused them to become brines as halides and alkalies became supersaturated; grains of halite (and, in the case of Monahans (1998), halite with sylvite inclusions) precipitated at low temperatures (less than or equal to 100 C) in the porous regolith. In both meteorites fluid inclusions were trapped inside the halite crystals. Primary fluid inclusions were trapped in the growing crystals; secondary inclusions formed subsequently from fluid trapped within healed fractures.

  12. Igneous Evolution of the Core and Mantle in the Parent Body of Group IVA Iron and Stony-Iron Meteorites

    NASA Astrophysics Data System (ADS)

    Scott, E. R. D.; McCoy, T. J.; Haack, H.; Taylor, G. J.

    1992-07-01

    peritectic liquids. Discussion: From the observed size and homogeneity of the Gibeon shower and our fractional crystallization modeling, we can infer that the parental liquid pool was at least many meters in size. Pools this big quickly sink through silicate (unless very reduced), so IVA metal very probably comes from a core. The wide range of metallographic cooling rates that is correlated with Ni concentration in IVA irons must therefore be an artefact. Liquids of pyroxene-silica compositions could be formed in the mantle (Prinz et al., 1984) but trapping them in the core at different stages of core crystallization seems very difficult. We prefer an origin for IVA stony irons by mixing olivine-pyroxene mantle material into the core during core solidification by processes like those that mixed olivine mantle into Fe,Ni cores to make pallasites, followed by addition of silica formed by oxidation of Si from the metal. Pieces of olivine-pyroxene, possibly in the form of a Brenham-like sponge, could be mixed into a crystallizing Fe,Ni core with about 2-4% S at temperatures around 1400 C. Pyroxene might be abundant in the mantle because small body size caused inefficient removal of trapped silicate liquid from an olivine cumulate. Alternatively, temperatures were never high enough to melt the mantle entirely. References: Haack H. and Scott E.R.D. (1992) Geochim. Cosmochim. Acta, submitted. Jones J.H. and Malvin (1990) Metall. Trans., 21B, 697-706. Prinz M., Nehru C.E., Delaney J.S., Fredriksson K., and Palme H. (1984) Meteoritics (abstract) 19, 291-292.

  13. Effect of parent body evolution on equilibrium and kinetic isotope fractionation: a combined Ni and Fe isotope study of iron and stony-iron meteorites

    NASA Astrophysics Data System (ADS)

    Chernonozhkin, Stepan M.; Goderis, Steven; Costas-Rodríguez, Marta; Claeys, Philippe; Vanhaecke, Frank

    2016-08-01

    Various iron and stony-iron meteorites have been characterized for their Ni and Fe isotopic compositions using multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS) after sample digestion and chromatographic separation of the target elements in an attempt to further constrain the planetary differentiation processes that shifted these isotope ratios and to shed light on the formational history and evolution of selected achondrite parent body asteroids. Emphasis was placed on spatially resolved isotopic analysis of iron meteorites, known to be inhomogeneous at the μm to mm scale, and on the isotopic characterization of adjacent metal and silicate phases in main group pallasites (PMG), mesosiderites, and the IIE and IAB complex silicate-bearing iron meteorites. In a 3-isotope plot of 60/58Ni versus62/58Ni, the slope of the best-fitting straight line through the laterally resolved Ni isotope ratio data for iron meteorites reveals kinetically controlled isotope fractionation (βexper = 1.981 ± 0.039, 1 SD), predominantly resulting from sub-solidus diffusion (with the fractionation exponent β connecting the isotope fractionation factors, as α62/58 =α60/58β). The observed relation between δ56/54Fe and Ir concentration in the metal fractions of PMGs and in IIIAB iron meteorites indicates a dependence of the bulk Fe isotopic composition on the fractional crystallization of an asteroidal metal core. No such fractional crystallization trends were found for the corresponding Ni isotope ratios or for other iron meteorite groups, such as the IIABs. In the case of the IIE and IAB silicate-bearing iron meteorites, the Fe and Ni isotopic signatures potentially reflect the influence of impact processes, as the degree of diffusion-controlled Ni isotope fractionation is closer to that of Fe compared to what is observed for magmatic iron meteorite types. Between the metal and olivine counterparts of pallasites, the Fe and Ni isotopic compositions show clearly

  14. Tungsten Isotope Dichotomy Among Iron Meteorite Parent Bodies: Implications for the Timescales of Accretion and Core Formation

    NASA Astrophysics Data System (ADS)

    Kruijer, T. S.; Kleine, T.

    2016-08-01

    We report new combined Pt and W isotope data for IC, IIC, IIF, IIIE, and IIIF iron meteorites, with the ultimate aim of better understanding the variable pre-exposure 182W/184W signatures observed among different iron meteorite groups.

  15. Catching Constrains on the Parent Body Genesis of Mesosiderites and a Possible Link to HED (Howardite-Eucrite-Diogenite) Meteorites - A New Hope?

    NASA Technical Reports Server (NTRS)

    Baecker, B.; Cohen, Barbara A.

    2016-01-01

    Mesosiderites (MES) are a group of enigmatic stony-iron meteorites exhibiting fragmental matrix breccias and irregular textures; e.g. [1-3]. Mesosiderites contain roughly equal volumes metal (Fe-Ni) and silicates often intimately mixed together (Fig.1). The silicates mostly consist of basaltic, gabbroic, and pyroxenitic components, and appear similar to eucrites and howardites; [4-8]. But unlike HEDs - and other differentiated parent body meteorite groups e.g. ureilites - mesosiderites contain high metal abundances. Several studies have been published to reveal the processes leading to the formation of mesosiderites and attempt to classifiy them [1], [2], [10-15]. Because the silicate inclusions in mesosiderites are often strongly metamorphosed after formation, it is difficult to assess the origin of the silicates and implications for the differentiation process of their parent body [15-17]. Several workers have advanced a formation hypothesis for the mesosiderites where an impact between differentiated bodies occurred prior to 4.47 Ga ago (e.g. [13,18], which could explain the possible incomplete dispersal of the colliding bodies due to their low cosmic ray exposure ages and their special thermal history. However, [13] discuss and favor the model for formation of mesosiderites with the collision of two differentiated bodies, along with disruption events and gravitational re-assembly. The mesosiderites have numerous gabbroid melt clasts with anomalous rare-earth- element (REE) - especially positive Eu - values [19, 20]. HEDs do not show the same. However, the heating mechanisms of both mesosiderites and HED's are puzzling. Mesosiderites are remarkable, they consist of a mix of basalts, which are only found on or near planetary surfaces and undifferentiated metal [1,2]. The probable model is that an asteroid containing a metallic magma impacted onto a second asteroid covered with basalt [18,21]. The mix was then buried under an insulating regolith, and cooled slowly

  16. ON THE EFFECT OF GIANT PLANETS ON THE SCATTERING OF PARENT BODIES OF IRON METEORITE FROM THE TERRESTRIAL PLANET REGION INTO THE ASTEROID BELT: A CONCEPT STUDY

    SciTech Connect

    Haghighipour, Nader; Scott, Edward R. D.

    2012-04-20

    In their model for the origin of the parent bodies of iron meteorites, Bottke et al. proposed differentiated planetesimals, formed in 1-2 AU during the first 1.5 Myr, as the parent bodies, and suggested that these objects and their fragments were scattered into the asteroid belt as a result of interactions with planetary embryos. Although viable, this model does not include the effect of a giant planet that might have existed or been growing in the outer regions. We present the results of a concept study where we have examined the effect of a planetary body in the orbit of Jupiter on the early scattering of planetesimals from the terrestrial region into the asteroid belt. We integrated the orbits of a large battery of planetesimals in a disk of planetary embryos and studied their evolutions for different values of the mass of the planet. Results indicate that when the mass of the planet is smaller than 10 M{sub Circled-Plus }, its effects on the interactions among planetesimals and planetary embryos are negligible. However, when the planet mass is between 10 and 50 M{sub Circled-Plus }, simulations point to a transitional regime with {approx}50 M{sub Circled-Plus} being the value for which the perturbing effect of the planet can no longer be ignored. Simulations also show that further increase of the mass of the planet strongly reduces the efficiency of the scattering of planetesimals from the terrestrial planet region into the asteroid belt. We present the results of our simulations and discuss their possible implications for the time of giant planet formation.

  17. Disordered biopyriboles, amphibole, and talc in the Allende meteorite: products of nebular or parent body aqueous alteration?

    PubMed

    Brearley, A J

    1997-05-16

    Transmission electron microscope observations of the Allende carbonaceous chondrite provided evidence of widespread hydrous phases replacing enstatite in chondrules. Calcic amphibole and talc occur in thin (less than 0.3 micrometer) crosscutting veins and as alteration products of primary chondrule glass in contraction cracks within the enstatite. In addition, talc and disordered biopyriboles were found replacing enstatite grains along cracks and fractures. Although rare hydrous phases have been reported in calcium- and aluminum-rich inclusions in the Allende meteorite, these observations suggest that aqueous fluids played a much more significant role in the mineralogical and geochemical evolution of Allende than has previously been thought.

  18. Meteorites

    NASA Astrophysics Data System (ADS)

    Jenniskens, Peter

    2015-08-01

    Meteorites have long been known to offer a unique window into planetary formation processes at the time of solar system formation and into the materials that rained down on Earth at the time of the origin of life. Their material properties determine the impact hazard of Near Earth Asteroids. Some insight into how future laboratory studies of meteorites and laboratory astrophysics simulations of relevant physical processes can help address open questions in these areas and generate new astronomical observations, comes from what was learned from the recent laboratory studies of freshly fallen meteorites. The rapid recovery of Almahata Sitta (a polymict Ureilite), Sutter's Mill (a CM chondrite regolith breccia), Novato (an L6 chondrite), and Chelyabinsk (an LL5 chondrite) each were followed by the creation of a meteorite consortium, which grew to over 50 researchers in the case of Chelyabinsk. New technologies were used to probe the organic content of the meteorites as well as their magnetic signatures, isotopic abundances, trapped noble gasses, and cosmogenic radio nucleides, amongst others. This has resulted in fascinating insight into the nature of the Ureilite parent body, the likely source region of the CM chondrites in the main asteroid belt, and the collisional environment of the CM parent body. This work has encouraged follow-up in the hope of catching more unique materials. Rapid response efforts are being developed that aim to recover meteorites as pristinely as possible from falls for which the approach orbit was measured. A significant increase in the number of known approach orbits for different meteorite types will help tie meteorite types to their asteroid family source regions. Work so far suggests that future laboratory studies may recognize multiple source regions for iron-rich ordinary chondrites, for example. Hope is that these source regions will give insight into the material properties of impacting asteroids. At least some future laboratory

  19. Neodymium, strontium and chromium isotopic studies of the LEW86010 and Angra dos Reis meteorites and the chronology of the angrite parent body

    NASA Technical Reports Server (NTRS)

    Nyquist, L. E.; Bansal, B.; Wiesmann, H.; Shih, C.-Y.

    1994-01-01

    Neodymium, stontium, and chromium isotopic studies of the LEW86010 angrite established its absolute age and the formation interval between its crystallization and condensation of Allende CAIs from the solar nebula. Pyroxene and phosphate were found to contain approximately 8% of its Sm and Nd inventory. A conventional Sm-147-Nd-143 isochron yielded an age of 4.53 +/- 0.04 Ga (2 sigma and Epsilon(sub Nd sup 143)) = 0.45 +/- 1.1. An Sm-146-Nd-142 isochron gives initial Sm-146/Sm-144 = 0.0076 +/- 0.0009 and Epsilon (sub Nd sup 142) = -2.5 +/- 0.4. The Rb-Sr analyses give initial Sr-87/Sr-86 Iota(sub Sr sup 87) = 0.698972 +/- 8 and 0.698970 +/- 18 for LEW and ADOR, respectively, relative to Sr-87/Sr-86 = 0.71025 for NBS987. The difference, Delta Iota(sub Sr Sup 87), between Iota (sub sr sup 87) for the angrites and literature values for Allende CAIs, corresponds to approximately Ma of growth in a solar nebula with a CI chondrite value of Rb-87/Sr-86 = 0.91, or approximately 5 Ma in a nebula with solar photospheric Rb-87/Sr-86 = 1.51. Excess Cr-53 from extinct Mn-53(t(sub 1/2) = 3.7 Ma)in LEW86010 corresponds to initial Mn-53/Mn-55 = 4.4 +/- 1.0 x 10(exp -5) for the inclusions as previously reported by the Paris group (Birck and Allegre, 1988). The Sm-146/Sm-144 value found for LEW86010 corresponds to solar system initial (Sm-146/Sm-144) = 0.0080 +/- 0.0009 for crystallization 8 Ma after Allende, the difference between Pb-Pb ages of angrites and Allende, or 0.0086 +/- 0.0009 for crystallation 18 Ma after Allende, using the Mn-Cr formation interval. The isotopic data are discussed in the context of a model in which an undifferentiated 'chondritic' parent body formed from the solar nebula approximately Ma after Allende CAIs and subsequently underwent differentiation accompanied by loss of volatiles. Parent bodies with Rb/Sr similar to that of CI, CM, or CO chondrites could satisfy the Cr and Sr isotopic systematics. If the angrite parent body had Rb/Sr similar to that of

  20. Enrichment of Non-Terrestrial L-Proteinogenic Amino Acids by Aqueous Alteration on the Tagish Lake Meteorite Parent Body

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    The distribution and isotopic and enantiomeric compositions of amino acids found in three distinct fragments of the Tagish Lake C2-type carbonaceous chondrite were investigated via liquid chromatography fluorescence detection time-of-flight mass spectrometry and gas chromatography isotope ratio mass spectrometry. Large L-enantiomeric excesses (L(sub ee) approx. 43 to 59%) of the a-hydrogen aspartic and glutamic amino acids were measured in Tagish Lake, whereas alanine, another alpha-hydrogen protein amino acid, was found to be nearly racemic (D approx. L) using both techniques. Carbon isotope measurements of D- and L-aspartic acid and D- and L-alanine in Tagish Lake fall well outside of the terrestrial range and indicate that the measured aspartic acid enantioenrichment is indigenous to the meteorite. Alternate explanations for the Lexcesses of aspartic acid such as interference from other compounds present in the sample, analytical biases, or terrestrial amino acid contamination were investigated and rejected. These results can be explained by differences in the solid-solution phase behavior of aspartic acid, which can form conglomerate enantiopure solids during crystallization, and alanine, which can only form racemic crystals.

  1. Pd-Ag chronology of volatile depletion, crystallization and shock in the Muonionalusta IVA iron meteorite and implications for its parent body

    NASA Astrophysics Data System (ADS)

    Horan, M. F.; Carlson, R. W.; Blichert-Toft, J.

    2012-10-01

    Muonionalusta, a Group IVA iron meteorite, was analyzed for its 107Pd-107Ag isotope systematics by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) in order to better constrain the initial Solar System abundance of 107Pd and to provide high resolution chronology of the evolution of its parent body. Six metal samples from Muonionalusta yield Ag abundances between 0.1012 and 1.461 ng/g, 107Ag/109Ag between 1.131 and 1.805, with 108Pd/109Ag ratios of 2201 to 52,300. The metal Pd/Ag and Ag isotopic data are correlated with a slope corresponding to a 107Pd/108Pd of (2.15±0.30)×10-5. If the Pd-Ag and Pb-Pb isotope systems closed at the same time in Muonionalusta, i.e., 2-3 Ma after CAI formation, then an initial Solar System ratio of 107Pd/108Pd=(2.8±0.5)×10-5 can be inferred. One troilite sample contains 8.478 ng/g Ag and has a 107Ag/109Ag ratio of 1.0833; its Pd concentration is 205.2 ng/g corresponding to a low 108Pd/109Ag of 13.56. The Pd-Ag results for this troilite plot near the extrapolation of the line passing through the metal points and define an initial 107Ag/109Ag that is substantially higher than chondritic, indicating that Muonionalusta formed from a precursor with high Pd/Ag. Pd and Ag concentrations in Muonionalusta metal suggest fractional crystallization from a source having Pd/Ag>4500, but the initial Ag isotopic composition for Muonionalusta troilite limits the duration of the high Pd/Ag to an interval of ≤0.6 Ma before cooling to closure of the Pd-Ag system. This result suggests that depletion of Ag and other volatile elements occurred shortly before accretion and cooling of the IVA parent body, and may have been associated with violent disruption of a progenitor to the IVA parent. Another troilite sample, its chromite inclusions and adjacent metal were isotopically homogenized locally after 107Pd had decayed, possibly by a later episode of shock >50 Ma after Solar System formation.

  2. Experimental Studies of Phase Equilibria of Meteorites and Planetary Bodies

    NASA Technical Reports Server (NTRS)

    Stolper, Edward M.

    2005-01-01

    The primary theme of this project was the application of experimental petrology and geochemistry to a variety of problems in meteoritics and planetary geology. The studies were designed to help develop constraints on the histories of primitive meteorites and their components, the environments in which they formed and evolved, and to understand quantitatively the processes involved in the evolution of igneous rocks on the earth and other planetary bodies. We undertook several projects relating to the origin of CAIs and chondrules. Systematics in the thermodynamic properties of CAI-like liquids were investigated and used to elucidate speciation of multi-valent cations and sulfide capacity of silicate melts and to constrain redox conditions and the vapor pressures of volatile species over molten chondrules. We experimentally determined vanadium speciation in meteoritic pyroxenes and in pyroxenes crystallized from CAI-like melts under very reducing conditions. We also found that bulk oxygen isotope compositions of chondrules in the moderately unequilibrated LL chondrites are related to the relative timing of plagioclase crystallization. We completed an experimental study on the vaporization of beta-SiC and SiO2 (glass or cristobalite) in reducing gases and established the conditions under which these presolar grains could have survived in the solar nebula. We expanded our technique for determining the thermodynamic properties of minerals and liquids to iron-bearing systems. We determined activity-composition relationships in Pt-Fe, Pt-Cr and Pt-Fe-Cr alloys. Results were used to determine the thermodynamic properties of chromite-picrochromite spinels including the free energy of formation of end-member FeCr2O4. We also established a new approach for evaluating Pt-Fe saturation experiments. We calculated the T-fO2 relationships in equilibrated ordinary chondrites and thereby constrained the conditions of metamorphism in their parent bodies.

  3. Meteoritic basalts: the nakhlites, their parental magmas, cooling rates, and equivalents on Earth. Final technical report

    SciTech Connect

    Treiman, A.H.

    1987-07-01

    Proposed one-bar phase equilibrium experiments, designed to determine the compositions of the nakhlites' parental magmas, are in progress. Proposed field studies on Earth, designed to find occurrences of rocks like the nakhlites, were extraordinarily successful. Other work supported in the past year included: attendance at the 1986 national meeting of the Geological Society of America; attendance at the 18th Lunar and Planetary Science Conference; completion and publication of a study of core formation in the SNC parent body; initiation of a study of the flux of SNC meteorites onto the Earth; and initiation of petrologic study of the Angra dos Reis achondrite.

  4. Meteoritic basalts: The nakhlites, their parental magmas, cooling rates, and equivalents on Earth

    NASA Technical Reports Server (NTRS)

    Treiman, Allan H.

    1987-01-01

    Proposed one-bar phase equilibrium experiments, designed to determine the compositions of the nakhlites' parental magmas, are in progress. Proposed field studies on Earth, designed to find occurrences of rocks like the nakhlites, were extraordinarily successful. Other work supported in the past year included: attendance at the 1986 national meeting of the Geological Society of America; attendance at the 18th Lunar and Planetary Science Conference; completion and publication of a study of core formation in the SNC parent body; initiation of a study of the flux of SNC meteorites onto the Earth; and initiation of petrologic study of the Angra dos Reis achondrite.

  5. 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.

  6. The 45th Annual Meteoritical Society Meeting

    NASA Technical Reports Server (NTRS)

    Jones, P. (Compiler); Turner, L. (Compiler)

    1982-01-01

    Impact craters and shock effects, chondrite formation and evolution, meteorites, chondrules, irons, nebular processes and meteorite parent bodies, regoliths and breccias, antarctic meteorite curation, isotopic studies of meteorites and lunar samples, organics and terrestrial weathering, refractory inclusions, cosmic dust, particle irradiations before and after compaction, and mineralogic studies and analytical techniques are discussed.

  7. Reconciling Hf-W Model Ages of IVB Parent Body with Numerical Models

    NASA Astrophysics Data System (ADS)

    Neumann, W.; Breuer, D.; Kleine, T.; Kruijer, T.

    2016-08-01

    We calculated the differentiation of the parent body of IVB iron meteorites comparing its evolution to the metal separation data. Our models are consistent with the separation ages inferred from the Hf-W chronology.

  8. The collisional evolution of chondritic parent bodies

    NASA Astrophysics Data System (ADS)

    Blum, Jürgen; Beitz, Eike; Parisi, Mirta Gabriela

    2015-11-01

    Most meteorites are fragments form recent collisions in the asteroid belt. The collision speed between two objects of the asteroid belt is given by the eccentricity and inclination of their respective Keplerian orbits. Typical values are on the order of a few km s-1. In such a hyper-velocity collision, the smaller collision partner (projectile) is destroyed, whereas, depending on the mass ratio of the colliding objects, a crater on the larger body (target) is formed or the target is entirely destroyed, too. The present size distribution of the asteroid belt suggests that an asteroid with 100 km radius is encountered ~1014 times during the lifetime of the Solar System by objects larger than 10 cm in radius, the formed craters cover the surface of the asteroid about 100 times.We will present a numerical study that simulates the statistical bombardment on an asteroidal surface and tracks the resulting morphological changes of the parent body due to the formation of craters, the compaction of the material beneath the craters as well as the formation of a regolith layer. The crater ejecta from recent impacts on a consolidated asteroid are then compared to the known meteorites, particularly concerning the distribution of shock stages.Comparing the compaction of ejected material from the simulated collisions that occurred during the last 20 Myrs, which is the mean cosmic ray exposure age of meteorites, with shock stages of meteorites, we find that meteorites most likely stem from smaller parent bodies that do not have a significant regolith layer. For larger objects that inevitably accrete regolith layers, a prediction of the thickness depending on the largest visible crater can be made. Additionally, we compare the crater distribution of an initially 100 km (radius) large object with a shape model of asteroid (21) Lutetia, assuming it to be initially formed spherical with a radius that is equal to its longest present ellipsoid length, and find a reasonable agreement

  9. Compositional Homogeneity of CM Parent Bodies

    NASA Astrophysics Data System (ADS)

    Vernazza, P.; Marsset, M.; Beck, P.; Binzel, R. P.; Birlan, M.; Cloutis, E. A.; DeMeo, F. E.; Dumas, C.; Hiroi, T.

    2016-09-01

    CM chondrites are the most common type of hydrated meteorites, making up ˜1.5% of all falls. Whereas most CM chondrites experienced only low-temperature (˜0°C–120°C) aqueous alteration, the existence of a small fraction of CM chondrites that suffered both hydration and heating complicates our understanding of the early thermal evolution of the CM parent body(ies). Here, we provide new constraints on the collisional and thermal history of CM-like bodies from a comparison between newly acquired spectral measurements of main-belt Ch/Cgh-type asteroids (70 objects) and existing laboratory spectral measurements of CM chondrites. It first appears that the spectral variation observed among CM-like bodies is essentially due to variations in the average regolith grain size. Second, the spectral properties of the vast majority (unheated) of CM chondrites resemble both the surfaces and the interiors of CM-like bodies, implying a “low” temperature (<300°C) thermal evolution of the CM parent body(ies). It follows that an impact origin is the likely explanation for the existence of heated CM chondrites. Finally, similarly to S-type asteroids and (2) Pallas, the surfaces of large (D > 100 km)—supposedly primordial—Ch/Cgh-type main-belt asteroids likely expose the interiors of the primordial CM parent bodies, a possible consequence of impacts by small asteroids (D < 10 km) in the early solar system.

  10. Compositional Homogeneity of CM Parent Bodies

    NASA Astrophysics Data System (ADS)

    Vernazza, P.; Marsset, M.; Beck, P.; Binzel, R. P.; Birlan, M.; Cloutis, E. A.; DeMeo, F. E.; Dumas, C.; Hiroi, T.

    2016-09-01

    CM chondrites are the most common type of hydrated meteorites, making up ˜1.5% of all falls. Whereas most CM chondrites experienced only low-temperature (˜0°C-120°C) aqueous alteration, the existence of a small fraction of CM chondrites that suffered both hydration and heating complicates our understanding of the early thermal evolution of the CM parent body(ies). Here, we provide new constraints on the collisional and thermal history of CM-like bodies from a comparison between newly acquired spectral measurements of main-belt Ch/Cgh-type asteroids (70 objects) and existing laboratory spectral measurements of CM chondrites. It first appears that the spectral variation observed among CM-like bodies is essentially due to variations in the average regolith grain size. Second, the spectral properties of the vast majority (unheated) of CM chondrites resemble both the surfaces and the interiors of CM-like bodies, implying a “low” temperature (<300°C) thermal evolution of the CM parent body(ies). It follows that an impact origin is the likely explanation for the existence of heated CM chondrites. Finally, similarly to S-type asteroids and (2) Pallas, the surfaces of large (D > 100 km)—supposedly primordial—Ch/Cgh-type main-belt asteroids likely expose the interiors of the primordial CM parent bodies, a possible consequence of impacts by small asteroids (D < 10 km) in the early solar system.

  11. Modelling the differentiation of the acapulcoite-lodranite parent body

    NASA Astrophysics Data System (ADS)

    Neumann, Wladimir Otto; Breuer, Doris; Spohn, Tilman; Henke, Stephan; Gail, Hans-Peter; Schwarz, Winfried; Trieloff, Mario; Hopp, Jens

    2015-08-01

    The acapulcoites and lodranites are rare groups of achondrites that originate from a common parent body. These meteorites are especially interesting because they experienced melting that was, however, not complete. We have performed thermal evolution models of the parent body of the Acapulco and Lodran-like meteorite clan, considering heating by short- and long-lived nuclides, temperature- and porosity-dependent parameters, and compaction of porous material. These models have been compared to the observed maximum metamorphic temperatures and thermo-chronological data available. An optimized set of parameters was determined, which fits to the data for the cooling histories of the meteorites. The optimum fit matches a body with the radius of 270 km that formed 1.66 Ma after CAIs with an initial temperature of 300 K. As the obtained temperatures are higher than the melting temperature of the metal phase, we considered in a second step a more detailed model that further includes melt migration by porous flow using the optimum fit parameters. Segregation of iron is assumed to start at a melt fraction threshold of 5%. The resulting structure has an iron core, a silicate mantle, a partially differentiated layer, an undifferentiated partially melted layer, and an outer unmelted shell. The temperature evolution obtained still fits to the cooling ages, and the burial depths derived range between 4 and 8 km. These layers experienced negligible melt migration, consistent with the observation of partial melting of the meteorites.Our results indicate a larger size and an earlier formation time of the acapulcoite-lodranite parent body, than typical estimates for ordinary chondrites’ parent bodies. This is also consistent with a higher degree of thermal metamorphism observed for the acapulcoite-lodranite parent body. The optimum fit initial temperature of 300 K suggests a formation closer to the Sun than ordinary chondrite parent bodies. The burial depths support excavation by a

  12. Phosphates in pallasite meteorites as probes of mantle processes in small planetary bodies

    NASA Technical Reports Server (NTRS)

    Davis, Andrew M.; Olsen, Edward J.

    1991-01-01

    Trace element analyses of the phosphates minerals in stony-iron pallasite meteorites are used here to investigate the magmatic history of the silicate portions of pallasites. In Eagle Station and seven other pallasites, the phosphates have relatively low concentrations of REEs and are strongly enriched in heavy relative to light REE. These patterns are consistent with formation of phosphate by subsolidus reactions between metal and silicate, in which phosphate inherits the REE pattern of olivine. In Springwater and Santa Rosalia, calcium-rich phosphates have higher concentrations of REE, are enriched in light relative to heavy REE, and have negative europium anomalies. These patterns are consistent with crystallization of phosphate from a europium-depleted chondritic liquid. This is unlikely to have happened near the base of the differentiating parent-body mantle; it suggests that some pallasites may come from regions of their parent bodies much nearer the surface than the core-mantle boundary.

  13. 221 Eos: a remnant of a partially differentiated parent body?

    NASA Astrophysics Data System (ADS)

    Mothé-Diniz, T.; Carvano, J. M.

    2005-11-01

    The asteroid 221 Eos and the objects belonging to its associated family - most of which belong to the K taxonomic class, have been traditionally associated with CO3/CV3 meteorites. The 52 color spectrum and the SMASSIR spectrum of 221 Eos in the NIR region, combined with the SMASSII spectrum in the visible, has now been compared to the whole RELAB meteorites database updated in July 2003. In this paper we present the first observational evidence that 221 Eos is analogous to a differentiated meteorite: the anomalous stone Divnoe. This link suggests that the the parent body of the Eos dynamical family was partially differentiated, with a thermal history quite different from what is currently accepted.

  14. 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.

  15. Cosmic-Ray-Exposure Ages of Diogenites and the Collisional History of the HED Parent Body or Bodies

    NASA Technical Reports Server (NTRS)

    Welten, K. C.; Lindner, L.; vanderBorg, K.; Loeken, T.; Scherer, P.; Schultz, L.

    1996-01-01

    Cosmic-ray-exposure ages of meteorites provide information on the collisional history of their parent bodies and the delivery mechanism of meteorites to Earth. The exposure-age distributions of ordinary chondrites show distinct patterns for H, L, and LL types, consistent with their origin on different parent bodies. The exposure-age distributions of howardites, eucrites. and diogenites (HEDS) show a common pattern with major peaks at 22 Ma and 38 Ma This provides additional evidence for a common origin of the HED meteorites, possibly 4 Vesta, although orbital dynamics calculations showed that the delivery of meteorites from Vesta to Earth is difficult. However, the discovery of several kilometer-sized Vesta-like asteroids in the region between Vesta and the 3:1 resonance suggested that these seem more likely parent bodies of the HEDs than Vesta itself. This implies that the exposure-age clusters may represent samples of several parent bodies. Therefore, the near-absence of diogenites with ages <20 Ma might be of interest for the composition of these kilometer-sized fragments of Vesta. Here we present cosmic-ray-exposure ages of 20 diogenites, including 9 new meteorites. In addition, we calculate the probability for each peak to occur by chance, assuming a constant production rate of HED fragments.

  16. International Workshop on Antarctic Meteorites

    NASA Technical Reports Server (NTRS)

    Annexstad, J. O.; Schultz, L.; Waenke, H.

    1986-01-01

    Topics addressed include: meteorite concentration mechanisms; meteorites and the Antarctic ice sheet; iron meteorites; iodine overabundance in meteorites; entrainment, transport, and concentration of meteorites in polar ice sheets; weathering of stony meteorites; cosmic ray records; radiocarbon dating; element distribution and noble gas isotopic abundances in lunar meteorites; thermoanalytical characterization; trace elements; thermoluminescence; parent sources; and meteorite ablation and fusion spherules in Antarctic ice.

  17. Magnetic evidence for a partially differentiated carbonaceous chondrite parent body

    PubMed Central

    Carporzen, Laurent; Weiss, Benjamin P.; Elkins-Tanton, Linda T.; Shuster, David L.; Ebel, Denton; Gattacceca, Jérôme

    2011-01-01

    The textures of chondritic meteorites demonstrate that they are not the products of planetary melting processes. This has long been interpreted as evidence that chondrite parent bodies never experienced large-scale melting. As a result, the paleomagnetism of the CV carbonaceous chondrite Allende, most of which was acquired after accretion of the parent body, has been a long-standing 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. Resolution of this conundrum requires a determination of the age and timescale over which Allende acquired its magnetization. Here, we report that Allende’s magnetization was acquired over several million years (Ma) during metasomatism on the parent planetesimal in a >  ∼ 20 μT field up to approximately 9—10 Ma after solar system formation. This field was present too recently and directionally stable for too long to have been generated by the protoplanetary disk or young Sun. The field intensity is in the range expected for planetesimal core dynamos, suggesting that CV chondrites are derived from the outer, unmelted layer of a partially differentiated body with a convecting metallic core.

  18. Abstracts for the 54th Annual Meeting of the Meteoritical Society

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Abstracts of the papers presented at 54th Annual Meeting of the Meteoritic Society are compiled. The following subject areas are covered: Antarctic meteorites; nebula and parent body processing; primary and secondary SNC parent planet processes; enstatite chondrites and aubrites; achondrite stew; refractory inclusions; meteorite exposure ages and sizes; interstellar/meteorite connections; lunar origins, processes and meteorites; craters, cratering and tektites; cretaceous-tertiary impact(s); IDPs (LDEF, stratosphere, Greenland and Antarctica); chondrules; and chondrites.

  19. Organic compounds in meteorites

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

    The problem of whether organic compounds originated in meteorites as a primary condensate from a solar gas or whether they were introduced as a secondary product into the meteorite during its residence in a parent body is examined by initially attempting to reconstruct the physical conditions during condensation (temperature, pressure, time) from clues in the inorganic matrix of the meteorite. The condensation behavior of carbon under these conditions is then analyzed on the basis of thermodynamic calculations, and compounds synthesized in model experiments on the condensation of carbon are compared with those actually found in meteorites. Organic compounds in meteorites seem to have formed by catalytic reactions of carbon monoxide, hydrogen, and ammonia in the solar nebula at 360 to 400 K temperature and about 3 to 7.6 microtorr pressure. The onset of these reactions was triggered by the formation of suitable catalysts (magnetite, hydrated silicates) at these temperatures.

  20. Thermal History of the Allende Parent Body

    NASA Astrophysics Data System (ADS)

    Weinbruch, S.; Armstrong, J. T.; Palme, H.

    1992-07-01

    ) data to low temperatures we assume that his experiments were buffered by QFM, resulting in faster diffusion at low temperatures compared to equations reported by Jones and Rubie (1991) and McCoy et al. (1991). At 800 K the observed Fe/Mg concentration profiles cannot be retained for more than 2 x 10^3 years (extrapolated from Buening and Buseck, 1973) to 2 x 10^5 years (extrapolated from Misener, 1974). At temperatures around 700 K and 600 K, respectively the observed concentration profiles could survive several million years. These temperatures may, thus, be regarded as an upper limit for peak metamorphic temperature in the Allende parent body. Extensive Fe/Mg interdiffusion between forsterite and fayalite leading to broad diffusion profiles frequently observed in Allende cannot be the result of parent body metamorphism but must have occurred at high temperatures in the solar nebula. References Buening D.K. and Buseck P.R. (1973) J. Geophys. Res. 78, 6852-6862. Jones R.H. and Rubie D.C. (1991) Earth Planet. Sci. Lett. 106, 73-86. McCoy T.J., Scott E.R.D., Jones R.H., Keil K. and Taylor G.J. (1991) Geochim. Cosmochim. Acta 55, 601-619. Misener D.J. (1974) In Geochemical Transport and Kinetics (ed. A.W. Hofmann), pp. 117-129. Carnegie Inst. Washington 634. Weinbruch S., Palme H., Muller W.F. and El Goresy A. (1990) Meteoritics 25, 115-125.

  1. 221 Eos: A remnant of a partially differentiated parent body?

    NASA Astrophysics Data System (ADS)

    Mothé-Diniz, T.; Carvano, J. M.

    2004-11-01

    The asteroid 221 Eos (K class), has been traditionally associated to CO/CV meteorites (Bell 1988). This association is based solely on spectral similarities with meteorites, and previously the best spectral analog to Eos was found to be the CO3 Warrenton (Burbine et al. 2001). The 52-color spectrum (http://pdssbn.astro.umd.edu/) and the SMASSIR spectrum (Burbine and Binzel 2001) of 221 Eos in the NIR region, combined with the SMASSII spectrum (Bus and Binzel 2001) in the visible, has now been compared to the whole RELAB meteorites database (http://www.planetary.brown.edu/relab/rel_pub/) updated on July 31, 2003. This comparison revealed a better spectral analog to Eos: the anomalous stone Divnoe, a primitive achondrite meteorite. Problems and implications of such match for the composition of Eos and its dynamical family will be discussed. This work has been supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPq/Brasil. References: Bell, J.F. 1988. A Probable Asteroidal Parent Body for the CV or CO Chondrites. Meteoritics 23, 256. Burbine, T.H. and Binzel, R.P. Bus, S.J. and Clark, B.E. 2001. K asteroids and CO3/CV3 chondrites. Icarus 36, 245. Burbine, T.H. and Binzel, R.P. 2002. Small Main-Belt Asteroid Spectroscopic Survey in the Near-Infrared. Icarus 159, 468. Bus, S.J. and Binzel, R.P. 2002. Phase II of the Small Main-Belt Asteroid Spectroscopic Survey: The Observations. Icarus 158, 106.

  2. Shock-Impact Melt Evidence and Possible Aqueous Alteration in Cali (H/L) Meteorite

    NASA Astrophysics Data System (ADS)

    Martínez-Jiménez, M.; Trigo-Rodríguez, J. M.; Brearley, A. J.

    2016-08-01

    We have described a thin section of the Cali meteorite (H/L4) in order to gain additional insights into the nature of the H/L chondrite parent body and a possible relation with the Tieschitz meteorite.

  3. Parent bodies of L and H chondrites: Times of catastrophic events.

    NASA Astrophysics Data System (ADS)

    Alexeev, V. A.

    1998-01-01

    An analysis of the distribution of 3He and 4He in L and H chondrites has shown that the parent body of L chondrites underwent a catastrophic collision in space 340 ( 50 Myr. This age differs considerably from the collision age of 520 ( 60 Myr given previously (Heymann, 1967). The parent body of H chondrites may also have undergone local heating and degassing about 200 Myr ago. Data for L chondrites argue in favour of Antarctic and non-Antarctic meteorites having originated from a common parent body.

  4. The parent magma of the nakhlite meteorites - Clues from melt inclusions

    NASA Technical Reports Server (NTRS)

    Harvey, Ralph P.; Mcsween, Harry Y., Jr.

    1992-01-01

    Several forms of trapped liquid found within nakhlite meteorites have been examined, including interstitial melt and magmatic inclusions within the cores of large olivine grains. Differences in the mineralogy and texture between two types of trapped melt inclusions, and between these inclusions and the mesostasis, indicate that vitrophyric inclusions are most appropriate for estimating the composition of a nakhlite parental magma in equilibrium with early-forming olivine and augite. Parent liquids were calculated from the mineralogy of large inclusions in Nakhla and Governador Valadares, using a system of mass-balance equations solved by linear regression methods. The chosen parental liquids were cosaturated in olivine and augite and had Mg/Fe values consistent with measured augite/liquid Kds. These parental magma compositions are similar to other published compositions for Nakhla, Chassigny, and Shergotty parental melts, and may correspond to a significant magma type on Mars.

  5. Modelling the thermal evolution and differentiation of the parent body of acapulcoites and lodranites

    NASA Astrophysics Data System (ADS)

    Neumann, Wladimir; Breuer, Doris; Spohn, Tilman; Henke, Stephan; Gail, Hans-Peter; Schwarz, Winfried; Trieloff, Mario; Hopp, Jens

    2015-04-01

    The acapulcoites and lodranites are rare groups of achondritic meteorites. Several characteristics such as unique oxygen isotope composition and similar cosmic ray exposure ages indicate that these meteorites originate from a common parent body (Weigel et al. 1999). By contrast to both undifferentiated and differentiated meteorites, acapulcoites and lodranites are especially interesting because they experienced melting that was, however, not complete (McCoy et al. 2006). Thus, unravelling their origin contributes directly to the understanding of the initial differentiation stage of planetary objects in the Solar system. The information preserved in the structure and composition of meteorites can be recovered by modelling the evolution of their parent bodies and comparing the results with the laboratory investigations. Model calculations for the thermal evolution of the parent body of the Acapulco and Lodran-like meteorite clan were performed using two numerical models. Both models (from [3] and [4], termed (a) and (b), respectively) solve a 1D heat conduction equation in spherical symmetry considering heating by short- and long-lived radioactive isotopes, temperature- and porosity-dependent parameters, compaction of initially porous material, and melting. The calculations with (a) were compared to the maximum metamorphic temperatures and thermo-chronological data available for acapulcoites and lodranites. Applying a genetic algorithm, an optimised set of parameters of a common parent body was determined, which fits to the data for the cooling histories of these meteorites. The optimum fit corresponds to a body with the radius of 270 km and a formation time of 1.66 Ma after the CAIs. Using the model by (b) that considers differentiation by porous flow and magmatic heat transport, the differentiation of the optimum fit body was calculated. The resulting structure consists of a metallic core, a silicate mantle, a partially differentiated layer, an undifferentiated

  6. Meteorite Dunite Breccia MIL 03443: A Probable Crustal Cumulate Closely Related to Diogenites from the HED Parent Asteroid

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, David W.

    2008-01-01

    There are numerous types of differentiated meteorites, but most represent either the crusts or cores of their parent asteroids. Ureilites, olivine-pyroxene-graphite rocks, are exceptions; they are mantle restites [1]. Dunite is expected to be a common mantle lithology in differentiated asteroids. In particular, models of the eucrite parent asteroid contain large volumes of dunite mantle [2-4]. Yet dunites are very rare among meteorites, and none are known associated with the howardite, eucrite, diogenite (HED) suite. Spectroscopic measurements of 4 Vesta, the probable HED parent asteroid, show one region with an olivine signature [5] although the surface is dominated by basaltic and orthopyroxenitic material equated with eucrites and diogenites [6]. One might expect that a small number of dunitic or olivine-rich meteorites might be delivered along with the HED suite. The 46 gram meteoritic dunite MIL 03443 (Fig. 1) was recovered from the Miller Range ice field of Antarctica. This meteorite was tentatively classified as a mesosiderite because large, dunitic clasts are found in this type of meteorite, but it was noted that MIL 03443 could represent a dunite sample of the HED suite [7]. Here I will present a preliminary petrologic study of two thin sections of this meteorite.

  7. Evidence from Polymict Ureilite Meteorites for a Single "Rubble-Pile" Ureilite Parent Asteroid Gardened by Several Distinct Impactors

    NASA Technical Reports Server (NTRS)

    Downes, Hilary; Mittlefehldt, David W.; Kita, Noriko T.; Valley, John W.

    2008-01-01

    Ureilites are ultramafic achondrite meteorites that have experienced igneous processing whilst retaining heterogeneity in mg# and oxygen isotope ratios. Polymict ureilites represent material derived from the surface of the ureilite parent asteroid(s). Electron microprobe analysis of more than 500 olivine and pyroxene clasts in six polymict ureilites reveals that they cover a statistically identical range of compositions to that shown by all known monomict ureilites. This is considered to be convincing evidence for derivation from a single parent asteroid. Many of the polymict ureilites also contain clasts that have identical compositions to the anomalously high Mn/Mg olivines and pyroxenes from the Hughes 009 monomict ureilite (here termed the Hughes cluster ). Four of the six samples also contain distinctive ferroan lithic clasts that have been derived from oxidized impactors. The presence of several common distinctive lithologies within the polymict ureilites is additional evidence that the ureilites were derived from a single parent asteroid. Olivine in a large lithic clast of augite-bearing ureilitic has an mg# of 97, extending the compositional range of known ureilite material. Our study confirms that ureilitic olivine clasts with mg#s < 85 are much more common than those with mg# > 85, which also show more variable Mn contents, including the melt-inclusion bearing "Hughes cluster" ureilites. We interpret this to indicate that the parent ureilite asteroid was disrupted by a major impact at a time when melt was still present in regions with a bulk mg# > 85, giving rise to the two types of ureilites: common ferroan ones that were already residual after melting and less common magnesian ones that were still partially molten when disruption occurred, some of which are the result of interaction of melts with residual mantle during disruption. A single daughter asteroid re-accreted from the disrupted remnants of the mantle of the proto-ureilite asteroid, giving rise

  8. Organics In Meteorites

    NASA Technical Reports Server (NTRS)

    Chang, Sherwood

    1996-01-01

    The variety of classes of organic compounds that occur in carbonaceous meteorites suggests a rich pre-planetary chemistry with possible connections to interstellar, solar nebular and parent body processes. Structural diversity prevails within all classes examined in detail. Among amino acids for instance, all possible isomers are found up to species containing 4-6 carbon atoms, with abundances decreasing with increasing molecular weight. Such diversity seems limited to those carbonaceous meteorites which show evidence of having been exposed to liquid water; meteorites lacking such evidence also show much lower abundances and less structural diversity in their organic contents. This apparent dependency on water suggests a role for cometary ices in the chemical evolution of organic compounds on parent bodies. Measurements of the stable isotope compositions of C, H, N and S in classes of compounds and at the individual compound level show strong deviations from average chondritic values. These deviations are difficult to explain by solar system or parent body processes, and precedents for some of these isotopic anomalies exist in interstellar (e.g., high D/H ratios) and circumstellar chemistry. Therefore, presolar origins for much if not all of the meteoritic organic compounds (or their precursors) is a distinct possibility. In contrast, evidence of solar nebular origins is either lacking or suspect. Results from molecular and isotopic analyses of meteoritic organics, from laboratory simulations and from a model of interstellar grain reactions will be used to flesh out the hypothesis that this material originated with interstellar chemistry, was distributed within the early solar system as cometary ices, and was subsequently altered on meteorite parent bodies to yield the observed compounds.

  9. Amphibole in Martian Meteorites: Composition and Implication for Volatile Content of Parental Magma

    NASA Astrophysics Data System (ADS)

    Williams, K. B.; Sonzogni, Y.; Treiman, A. H.

    2013-12-01

    Titanium-rich amphibole is present in melt inclusions in many martian (SNC) meteorites, suggesting that martian magmas contained water. Amphibole has been reported in melt inclusions within olivine grains in chassignites [1-3], and occurs in melt inclusions within pigeonite grains in most shergottites [4-10]. This study focuses on a comparison of amphibole compositions in two olivine-phyric shergottites: Tissint and Elephant Moraine (EETA) 79001, Lithology A. While amphibole (commonly of kaersutitic composition) is rare in martian meteorites, the mineral is widespread and may be useful in constraining volatile abundances in the martian mantle. Amphibole incorporates hydroxyl into its mineral structure on its O(3) site, which can also contain F-, Cl-, and O2-. Previous chemical analyses of amphiboles in martian meteorites show low halogen abundances, implying high proportions of OH- and/or O2- in the O(3) site [6, 11]. Presence of O2- on O(3) is not considered in this study, even though oxy-kaersutite can be stable at 1 bar pressure [11, 12]. Our chemical data on amphibole in martian meteorites will expand the current compositional database and provide amphibole water content estimates that can then be used to constrain the water content of the parental magma. Amphiboles were identified in polished thin sections of Tissint and EETA79001A by their yellow-orange to light brown pleochroism. Consistent with previous observations of amphibole in shergottites [4-10], the amphiboles are present only in melt inclusions in the cores of pigeonite grains, and never in augite, olivine, or mesostasis. The amphibole grains are subhedral, and range up to 15 μm in diameter. Amphibole formulae were calculated from chemical analyses by normalizing to 23 O, assuming that all iron is ferrous, and assuming that halogens and hydroxyl fully occupy the O(3) site (i.e., F-+Cl-+OH-= 2). Variability in iron oxidation and the possibility of internal amphibole dehydrogenation provide

  10. 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.

  11. Paleomagnetism of a primitive achondrite parent body: The acapulcoite-lodranites

    NASA Astrophysics Data System (ADS)

    Schnepf, N. R.; Weiss, B. P.; Andrade Lima, E.; Fu, R. R.; Uehara, M.; Gattacceca, J.; Wang, H.; Suavet, C. R.

    2014-12-01

    Primitive achondrites are a recently recognized meteorite grouping with textures and compositions intermediate between unmelted meteorites (chondrites) and igneous meteorites (achondrites). Their existence demonstrates prima facie that some planetesimals only experienced partial rather than complete melting. We present the first paleomagnetic measurements of acapulcoite-lodranite meteorites to determine the existence and intensity of ancient magnetic fields on their parent body. Our paleomagnetic study tests the hypothesis that their parent body had an advecting metallic core, with the goal of providing one of the first geophysical constraints on its large-scale structure and the extent of interior differentiation. In particular, by analyzing samples whose petrologic textures require an origin on a partially differentiated body, we will be able to critically test a recent proposal that some achondrites and chondrite groups could have originated on a single body (Weiss and Elkins-Tanton 2013). We analyzed samples of the meteorites Acapulco and Lodran. Like other acapulcoites and lodranites, these meteorites are granular rocks containing large (~0.1-0.3 mm) kamacite and taenite grains along with similarly sized silicate crystals. Many silicate grains contain numerous fine (1-10 μm) FeNi metal inclusions. Our compositional measurements and rock magnetic data suggest that tetrataenite is rare or absent. Bulk paleomagnetic measurements were done on four mutually oriented bulk samples of Acapulco and one bulk sample of Lodran. Alternating field (AF) demagnetization revealed that the magnetization of the bulk samples is highly unstable, likely due to the large (~0.1-0.3 mm) interstitial kamacite grains throughout the samples. To overcome this challenge, we are analyzing individual ~0.2 mm mutually oriented silicate grains extracted using a wire saw micromill. Preliminary SQUID microscopy measurements of a Lodran silicate grain suggest magnetization stable to AF levels of

  12. Parental perception of preschool child body weight.

    PubMed

    Garrett-Wright, Dawn

    2011-10-01

    Obesity in preschoolers has risen dramatically in the last decade. Although studies have demonstrated that parents of preschoolers have incorrect perceptions of their child's body weight, little is known about the factors that may be associated with these perceptions. The purpose of this study was to examine the relationships between parental perceptions of preschool child body weight and parental psychosocial factors. Quantitative analyses included descriptive statistics, correlations, and regression analyses. More than one third of the children in the sample were at risk for being overweight or were already overweight. However, less than 6% of parents felt that their child had an elevated body weight. Results from univariate logistic regression analyses demonstrated that the parent's health literacy level was a significant predictor of the accuracy of their perceptions regarding their child's body weight (p < .05). Parental concern regarding child weight and perceived level of efficacy did not significantly predict the accuracy of their perceptions. Results from this study indicate that assessing parental perceptions of preschool child body weight can help providers accurately understand how parents view their children and lead to tailored educational interventions. In addition, the results support previous research suggesting that parental health literacy is a key to providing high-quality family-centered care.

  13. Paucity of Tagish Lake-like parent bodies in the Asteroid Belt and among Jupiter Trojans

    NASA Astrophysics Data System (ADS)

    Vernazza, P.; Fulvio, D.; Brunetto, R.; Emery, J. P.; Dukes, C. A.; Cipriani, F.; Witasse, O.; Schaible, M. J.; Zanda, B.; Strazzulla, G.; Baragiola, R. A.

    2013-07-01

    We present new results for ion irradiation experiments performed on fragments of the Tagish Lake (TL) meteorite. These experiments were focused on (a) quantifying the effect of the solar wind on spectral reflectance and (b) identifying the parent bodies of TL within the Asteroid Belt and or Jupiter Trojans. In the visible and near-infrared, we observe a flattening and brightening of the reflectance with progressive irradiation; in the mid-infrared, we observe a small shift towards longer wavelengths of the main emission feature at 10 μm consistent with what is observed in silicates, likely caused by amorphization. We evaluated possible parent bodies for Tagish Lake by comparing its total reflectance in the visible and spectral changes in the 0.4-25 μm range with available measurements for main belt asteroids and Jupiter Trojans (asteroid data includes measurements from the WISE, SMASS and Spitzer surveys as well as IRTF observations). The low reflectance of TL compared to asteroid albedos shows that TL-like bodies are very rare among Jupiter Trojans (<0.02% of the total population) and that they exist in a very small proportion (<4.5% of the total population) among main belt asteroids, where only one asteroid, 368 Haidea, was found to match both TL's spectrum and reflectance. Additionally, TL-like bodies would be preferentially located in the outer Asteroid Belt (2.85-3.3 AU) further away from the Sun than the average current location of most Ch- and Cgh-types, these objects being the likely parent bodies of CM-type chondritic meteorites. It thus appears that the location of both meteorite groups (TL and CM) must be different, with TL having formed further away from the Sun than CMs. We find that there are by far more parent bodies of CM than TL-like meteorites, which still remains to be understood.

  14. Organic Molecules in Meteorites

    NASA Astrophysics Data System (ADS)

    Martins, Zita

    2015-08-01

    Carbonaceous meteorites are primitive samples from the asteroid belt, containing 3-5wt% organic carbon. The exogenous delivery of organic matter by carbonaceous meteorites may have contributed to the organic inventory of the early Earth. The majority (>70%) of the meteoritic organic material consist of insoluble organic matter (IOM) [1]. The remaining meteoritic organic material (<30%) consists of a rich organic inventory of soluble organic compounds, including key compounds important in terrestrial biochemistry [2-4]. Different carbonaceous meteorites contain soluble organic molecules with different abundances and distributions, which may reflect the extension of aqueous alteration or thermal metamorphism on the meteorite parent bodies. Extensive aqueous alteration on the meteorite parent body may result on 1) the decomposition of α-amino acids [5, 6]; 2) synthesis of β- and γ-amino acids [2, 6-9]; 3) higher relative abundances of alkylated polycyclic aromatic hydrocarbons (PAHs) [6, 10]; and 4) higher L-enantiomer excess (Lee) value of isovaline [6, 11, 12].The soluble organic content of carbonaceous meteorites may also have a contribution from Fischer-Tropsch/Haber-Bosch type gas-grain reactions after the meteorite parent body cooled to lower temperatures [13, 14].The analysis of the abundances and distribution of the organic molecules present in meteorites helps to determine the physical and chemical conditions of the early solar system, and the prebiotic organic compounds available on the early Earth.[1] Cody and Alexander (2005) GCA 69, 1085. [2] Cronin and Chang (1993) in: The Chemistry of Life’s Origin. pp. 209-258. [3] Martins and Sephton (2009) in: Amino acids, peptides and proteins in organic chemistry. pp. 1-42. [4] Martins (2011) Elements 7, 35. [5] Botta et al. (2007) MAPS 42, 81. [6] Martins et al. (2015) MAPS, in press. [7] Cooper and Cronin (1995) GCA 59, 1003. [8] Glavin et al. (2006) MAPS. 41, 889. [9] Glavin et al. (2011) MAPS 45, 1948. [10

  15. Organic Chemistry of Meteorites

    NASA Technical Reports Server (NTRS)

    Chang, S.; Morrison, David (Technical Monitor)

    1994-01-01

    Studies of the molecular structures and C,N,H-isotopic compositions of organic matter in meteorites reveal a complex history beginning in the parent interstellar cloud which spawned the solar system. Incorporation of interstellar dust and gas in the protosolar nebula followed by further thermal and aqueous processing on primordial parent bodies of carbonaceous, meteorites have produced an inventory of diverse organic compounds including classes now utilized in biochemistry. This inventory represents one possible set of reactants for chemical models for the origin of living systems on the early Earth. Evidence bearing on the history of meteoritic organic matter from astronomical observations and laboratory investigations will be reviewed and future research directions discussed.

  16. RAPID TIMESCALES FOR MAGMA OCEAN CRYSTALLIZATION ON THE HOWARDITE-EUCRITE-DIOGENITE PARENT BODY

    SciTech Connect

    Schiller, Martin; Paton, Chad; Bizzarro, Martin; Baker, Joel; Creech, John; Millet, Marc-Alban; Irving, Anthony

    2011-10-10

    Asteroid 4 Vesta has long been postulated as the source for the howardite-eucrite-diogenite (HED) achondrite meteorites. Here we show that Al-free diogenite meteorites record variability in the mass-independent abundance of {sup 26}Mg ({sup 26}Mg*) that is correlated with their mineral chemistry. This suggests that these meteorites captured the Mg-isotopic evolution of a large-scale differentiating magma body with increasing {sup 27}Al/{sup 24}Mg during the lifespan of the short-lived {sup 26}Al nuclide (t {sub 1/2} {approx} 730,000 yr). Thus, diogenites and eucrites represent crystallization products of a large-scale magma ocean associated with the differentiation and magmatic evolution of the HED parent body. The {sup 26}Mg* composition of the most primitive diogenites requires onset of the magma ocean crystallization within 0.6{sup -0.4} {sub +0.5} Myr of solar system formation. Moreover, {sup 26}Mg* variations among diogenites and eucrites imply that near complete solidification of the HED parent body occurred within the following 2-3 Myr. Thermal models predict that such rapid cooling and magma ocean crystallization could only occur on small asteroids (<100 km), implying that 4 Vesta is not the source of the HED meteorites.

  17. New evidence of meteoritic origin of the Tunguska cosmic body

    NASA Astrophysics Data System (ADS)

    Kvasnytsya, Victor; Wirth, Richard; Dobrzhinetskaya, Larissa; Matzel, Jennifer; Jacobsen, Benjamin; Hutcheon, Ian; Tappero, Ryan; Kovalyukh, Mykola

    2013-08-01

    Diamond-lonsdaleite-graphite micro-samples collected from peat after the 1908 catastrophic blast in the Tunguska area were studied with scanning (SEM) and transmission electron (TEM) microscopy, NanoSecondary Ion Mass Spectrometry (NanoSIMS) and Х-ray synchrotron technique. The high-pressure carbon allotropes in the Tunguska samples are being described for the first time and contain inclusions of FeS (troilite), Fe-Ni (taenite), γ-Fe and (FeNi)3P (schreibersite). The samples are nodule-like in shape and consist of 99.5% carbon minerals, e.g. diamond>lonsdaleite>graphite. Micro- and nanoinclusions of troilite (up to 0.5 vol%), taenite, γ-iron and schreibersite fill cracks, cleavages and pores in the carbon matrix. Carbon isotope studies from the two analyses of the Tunguska foil showed δ13C=-16.0±1.9‰ and δ13C=-15.2±2.1‰, suggesting δ13C=-15.6±2‰ as an average characteristic of the carbon reservoir. That value is close to δ13C of some extraterrestrial samples. A negligible concentration of Ir and Os in the carbonaceous matrix promotes some controversial interpretation of the origin of the studied materials. Attributing this fact to the primary inhomogeneity, and considering the micro-structural features such as cracks, deformation of the crystal lattices, etc. coupled with high-pressure carbon allotropes association with metals, sulfides and phosphides, and the high ratio of Fe:Ni=22:1 suggest that the studied samples are meteorite micro-remnants.

  18. INAA of CAIs from the Maralinga CK4 chondrite: Effects of parent body thermal metamorphism

    NASA Technical Reports Server (NTRS)

    Lindstrom, D. J.; Keller, L. P.; Martinez, R. R.

    1993-01-01

    Maralinga is an anomalous CK4 carbonaceous chondrite which contains numerous Ca-, Al-rich inclusions (CAI's) unlike the other members of the CK group. These CAI's are characterized by abundant green hercynitic spinel intergrown with plagioclase and high-Ca clinopyroxene, and a total lack of melilite. Instrumental Neutron Activation Analysis (INAA) was used to further characterize the meteorite, with special focus on the CAI's. High sensitivity INAA was done on eight sample disks about 100-150 microns in diameter obtained from a normal 30 micron thin section with a diamond microcoring device. The CAI's are enriched by 60-70X bulk meteorite values in Zn, suggesting that the substantial exchange of Fe for Mg that made the spinel in the CAI's hercynitic also allowed efficient scavenging of Zn from the rest of the meteorite during parent body thermal metamorphism. Less mobile elements appear to have maintained their initial heterogeneity.

  19. 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.

  20. 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.

  1. Cliftonite in meteorites: A proposed origin

    USGS Publications Warehouse

    Brett, R.; Higgins, G.T.

    1967-01-01

    Cliftonite, a polycrystalline aggregate of graphite with cubic morphology, is known in ten meteorites. Some workers have considered it to be a pseudomorph after diamond, and have used the proposed diamond ancestry as evidence of a meteoritic parent body of at least lunar dimensions. We have synthesized cliftonite in Fe-Ni-C alloys in vacuum, as a product of decomposition of cohenite [(Fe,Ni)3C]. We therefore suggest that a high pressure origin is unnecessary for meteorites which contain cliftonite, and that these meteorites were formed at low pressures. This conclusion is in agreement with other recent evidence.

  2. 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.

  3. Meteorites, Microfossils and Exobiology

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.

    1997-01-01

    The discovery of evidence for biogenic activity and possible microfossils in a Martian meteorite may have initiated a paradigm shift regarding the existence of extraterrestrial microbial life. Terrestrial extremophiles that live in deep granite and hydrothermal vents and nanofossils in volcanic tuffs have altered the premise that microbial life and microfossils are inconsistent with volcanic activity and igneous rocks. Evidence for biogenic activity and microfossils in meteorites can no longer be dismissed solely because the meteoritic rock matrix is not sedimentary. Meteorite impact-ejection and comets provide mechanisms for planetary cross-contamination of biogenic chemicals, microfossils, and living microorganisms. Hence, previously dismissed evidence for complex indigenous biochemicals and possible microfossils in carbonaceous chondrites must be re-examined. Many similar, unidentifiable, biological-like microstructures have been found in different carbonaceous chondrites and the prevailing terrestrial contaminant model is considered suspect. This paper reports the discovery of microfossils indigenous to the Murchison meteorite. These forms were found in-situ in freshly broken, interior surfaces of the meteorite. Environmental Scanning Electron Microscope (ESEM) and optical microscopy images indicate that a population of different biological-like forms are represented. Energy Dispersive Spectroscopy reveals these forms have high carbon content overlaying an elemental distribution similar to the matrix. Efforts at identification with terrestrial microfossils and microorganisms were negative. Some forms strongly resemble bodies previously isolated in the Orgueil meteorite and considered microfossils by prior researchers. The Murchison forms are interpreted to represent an indigenous population of the preserved and altered carbonized remains (microfossils) of microorganisms that lived in the parent body of this meteorite at diverse times during the past 4.5 billion

  4. Iron Isotope Compositions of Achondritic Meteorites from Distinct Parent Bodies

    NASA Astrophysics Data System (ADS)

    Dybal, E. M. K.; Wadhwa, M.; Romaniello, S.; Hines, R.

    2016-08-01

    We report the Fe isotope compositions of primitive and differentiated achondrites. The goal was to study a variety of achondrites that formed on distinct planetesimals to gain insights into the effects of differentiation on Fe isotope fractionation.

  5. Siderophile elements in brecciated HED meteorites and the nature of projectile materials in HED meteorites

    NASA Astrophysics Data System (ADS)

    Shirai, N.; Okamoto, C.; Yamaguchi, A.; Ebihara, M.

    2016-03-01

    Petrological, mineralogical and geochemical studies were performed on five brecciated HED meteorites (ALH 76005, EET 92003, LEW 85300, LEW 87026 and GRO 95633) in order to elucidate the nature of impactors on the HED parent body. Some brecciated HED meteorites contain exotic materials such as FeNi-metal grains with low Co/Ni ratios (ALH 76005, EET 92003 and GRO 95633) and carbonaceous chondrite clasts (LEW 85300) in a clastic and/or impact melt matrix. Such exotic materials were incorporated during brecciation. Platinum group element (PGE) abundances vary significantly (CI × 0.002-0.05), but are higher than those of pristine rocks from the HED parent body. The PGE ratios for the five HED meteorites are inconsistent with each other, implying that the impactor components of each HED meteorites are different from each other. The various PGE ratios are consistent with those for metals from chondrites and iron meteorites, and carbonaceous chondrites. This study provides the evidence that IAB and IVA iron meteorites, and carbonaceous chondrites (CM, CO, CV, CK, CB and CR), ordinary chondrites (L and H) and enstatite chondrite (EL) are candidates of the impactor materials on the HED parent body. It is highly probable that significant amounts of siderophile elements were incorporated into the inner solar system objects like the HED parent body from both chondritic materials and differentiated materials like iron meteorites during heavy bombardment. The HED meteorites in this study and metals from mesosiderite have different Pd/Ir ratios, probably implying that HED meteorites and mesosiderites formed either at distinct settings on one common parent body or on similar parent bodies.

  6. Water Transport and the Evolution of CM Parent Bodies

    NASA Technical Reports Server (NTRS)

    Coker, R.; Cohen, B.

    2014-01-01

    Extraterrestrial water-bearing minerals are of great importance both for understanding the formation and evolution of the solar system and for supporting future human activities in space. Asteroids are the primary source of meteorites, many of which show evidence of an early heating episode and varying degrees of aqueous alteration. The origin and characterization of hydrated minerals (minerals containing H2O or OH) among both the main-belt and near-earth asteroids is important for understanding a wide range of solar system formation and evolutionary processes, as well as for planning for human exploration. Current hypotheses postulate asteroids began as mixtures of water ice and anhydrous silicates. A heating event early in solar system history was then responsible for melting the ice and driving aqueous alteration. The link between asteroids and meteorites is forged by reflectance spectra, which show 3-µm bands indicative of bound OH or H2O on the C-class asteroids, which are believed to be the parent bodies of the carbonaceous chondrites in our collections. The conditions at which aqueous alteration occurred in the parent bodies of carbonaceous chondrites are thought to be well-constrained: at 0-25 C for less than 15 Myr after asteroid formation. In previous models, many scenarios exhibit peak temperatures of the rock and co-existing liquid water in more than 75 percent of the asteroid's volume rising to 150 C and higher, due to the exothermic hydration reactions triggering a thermal runaway effect. However, even in a high porosity, water-saturated asteroid very limited liquid water flow is predicted (distances of 100's nm at most). This contradiction has yet to be resolved. Still, it may be possible for water to become liquid even in the near-surface environment, for a long enough time to drive aqueous alteration before vaporizing or freezing then subliming. Thus, we are using physics- and chemistry-based models that include thermal and fluid transport as well

  7. 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.

  8. Meteorite regolithic breccias

    NASA Technical Reports Server (NTRS)

    Bunch, T. E.; Rajan, R. S.

    1988-01-01

    In addition to endogenic processes such as heating and aqueous activity, meteorite parent bodies were subjected also to exogenic processing brought about by the impact of the other solar-system objects. Such impacts can produce a variety of effects, ranging from shock metamorphism of individual mineral grains to production of breccias; i.e., rocks consisting of mixtures of disparate lithic units. The present paper reviews recent studies of such breccias, which have generated significant information about the accretional growth of parent bodies, as well as their evolution, composition, stratigraphy, and geological processing.

  9. Organic chemistry in meteorites

    NASA Astrophysics Data System (ADS)

    Botta, Oliver

    2002-11-01

    Carbonaceous chondrites contain a suite of soluble organic compounds that possess characteristics that help to understand their formation and to trace back the early history of the solar system. Relative amino acid abundances can be used to discriminate between different parent bodies. The Tagish Lake meteorite is a unique sample from a new type of solar system object that will help to further constrain the physical and chemical conditions found on parent bodies. Enantiomeric excesses have been detected in nonbiological amino acids in the Murchison and Murray meteorites that are still difficult to explain in the current scenario for the synthesis of extraterrestrial amino acids. Finally, new classes of compounds, dipeptides and sugar-related molecules, have been detected in CM carbonaceous chondrites.

  10. The Effect of Early Impacts on Iron Meteorite Cooling Rates

    NASA Astrophysics Data System (ADS)

    Lyons, R. J.; Ciesla, F. J.; Bowling, T. J.; Davison, T. M.; Collins, G. S.

    2016-08-01

    Sizes and structures of iron meteorite parent bodies have been inferred by comparing metallographic cooling rates to thermal evolution models. We examine the effect that impacts would have on cooling rates of cores of differentiated planetesimals.

  11. Enstatite chondrites and enstatite achondrites (aubrites) were not derived from the same parent body

    USGS Publications Warehouse

    Brett, R.; Keil, Klaus

    1986-01-01

    Enstatite achondrites (aubrites) were not derived from known enstatite chondrites by melting and fractionation on one and the same parent body, for these and other reasons: (1) There is no satisfactory mechanism for fractionating metal plus troilite in enstatite chondrites to form these phases in different proportions and with different Ti contents in aubrites. (2) Many enstatite chondrites and aubrites are regolith or fragmental breccias, but clasts of one within the other have not been found. (3) Cosmic ray exposure ages of the two groups are difficult to explain if they are from the same parent body, but are easy to explain if they are from different parent bodies. Siderophile element abundances in metal from the Mt. Egerton meteorite, which consists of enstatite and metallic Fe,Ni, preclude it from being a complementary differentiate of the aubrites. Rather, it appears that Mt. Egerton was formed from the same source material as enstatite chondrites, but the components were mixed in different proportions. ?? 1986.

  12. Composition and evolution of the eucrite parent body - Evidence from rare earth elements. [extraterrestrial basaltic melts

    NASA Technical Reports Server (NTRS)

    Consolmagno, G. J.; Drake, M. J.

    1977-01-01

    Quantitative modeling of the evolution of rare earth element (REE) abundances in the eucrites, which are plagioclase-pigeonite basalt achondrites, indicates that the main group of eucrites (e.g., Juvinas) might have been produced by approximately 10% equilibrium partial melting of a single type of source region with initial REE abundances which were chondritic relative and absolute. Since the age of the eucrites is about equal to that of the solar system, extensive chemical differentiation of the eucrite parent body prior to the formation of eucrites seems unlikely. If homogeneous accretion is assumed, the bulk composition of the eucrite parent body can be estimated; two estimates are provided, representing different hypotheses as to the ratio of metal to olivine in the parent body. Since a large number of differentiated olivine meteorites, which would represent material from the interior of the parent body, have not been detected, the eucrite parent body is thought to be intact. It is suggested that the asteroid 4 Vesta is the eucrite parent body.

  13. Long-lived magnetism from solidification-driven convection on the pallasite parent body.

    PubMed

    Bryson, James F J; Nichols, Claire I O; Herrero-Albillos, Julia; Kronast, Florian; Kasama, Takeshi; Alimadadi, Hossein; van der Laan, Gerrit; Nimmo, Francis; Harrison, Richard J

    2015-01-22

    Palaeomagnetic measurements of meteorites suggest that, shortly after the birth of the Solar System, the molten metallic cores of many small planetary bodies convected vigorously and were capable of generating magnetic fields. Convection on these bodies is currently thought to have been thermally driven, implying that magnetic activity would have been short-lived. Here we report a time-series palaeomagnetic record derived from nanomagnetic imaging of the Imilac and Esquel pallasite meteorites, a group of meteorites consisting of centimetre-sized metallic and silicate phases. We find a history of long-lived magnetic activity on the pallasite parent body, capturing the decay and eventual shutdown of the magnetic field as core solidification completed. We demonstrate that magnetic activity driven by progressive solidification of an inner core is consistent with our measured magnetic field characteristics and cooling rates. Solidification-driven convection was probably common among small body cores, and, in contrast to thermally driven convection, will have led to a relatively late (hundreds of millions of years after accretion), long-lasting, intense and widespread epoch of magnetic activity among these bodies in the early Solar System. PMID:25612050

  14. About Tagish Lake as a Potential Parent Body for Polar Micrometeorites; Clues from their Hydrogen Isotopic Compositions

    NASA Technical Reports Server (NTRS)

    Engrand, C.; Gounelle, M.; Zolensky, M. E.; Duprat, J.

    2003-01-01

    The origin of the Antarctic micrometeorites (AMMs) is still a matter of debate. Their closest meteoritic counterparts are the C2 chondrites, but the match is not perfect, and the parent body(ies) of the AMMs is(are) still to be identified. Tagish Lake is a new meteorite fall which bears similarity with CI1 and CM2 chondrites, but is distinct from both. Based on the mineralogy of phyllosilicates, Noguchi et al. proposed that the phyllosilicate-rich AMMs and the Tagish Lake meteorites could derive from similar asteroids. The hydrogen isotopic compositions of extra-terrestrial samples can be used to get some insight on their origin. The D/H ratios of AMMs and of Tagish Lake have been measured, but using different analytical techniques. They are therefore not directly comparable. We performed additional hydrogen isotopic analyses of fragments of Tagish Lake using the same experimental setup previously used for the measurement of the hydrogen isotopic composition of AMMs. In this work, we could also analyze separately both lithologies of Tagish Lake (carbonate-poor and -rich). The distributions of delta D values measured in the two lithologies of Tagish Lake are very similar, indicating that fluids with similar hydrogen isotopic compositions altered the meteorite on the parent body for the two lithologies. Yet, the hydrogen isotopic composition of Tagish Lake is different from that of AMMs, suggesting that they do not derive from the same parent body.

  15. Amino acids in the Tagish Lake Meteorite

    NASA Technical Reports Server (NTRS)

    Kminek, G.; Botta, O.; Glavin, D. P.; Bada, J. L.

    2002-01-01

    High-performance liquid chromatography (HPLC) based amino acid analysis of a Tagish Lake meteorite sample recovered 3 months after the meteorite fell to Earth have revealed that the amino acid composition of Tagish Lake is strikingly different from that of the CM and CI carbonaceous chondrites. We found that the Tagish Lake meteorite contains only trace levels of amino acids (total abundance = 880 ppb), which is much lower than the total abundance of amino acids in the CI Orgueil (4100 ppb) and the CM Murchison (16 900 ppb). Because most of the same amino acids found in the Tagish Lake meteorite are also present in the Tagish Lake ice melt water, we conclude that the amino acids detected in the meteorite are terrestrial contamination. We found that the exposure of a sample of Murchison to cold water lead to a substantial reduction over a period of several weeks in the amount of amino acids that are not strongly bound to the meteorite matrix. However, strongly bound amino acids that are extracted by direct HCl hydrolysis are not affected by the leaching process. Thus even if there had been leaching of amino acids from our Tagish Lake meteorite sample during its 3 month residence in Tagish Lake ice and melt water, a Murchison type abundance of endogenous amino acids in the meteorite would have still been readily detectable. The low amino acid content of Tagish Lake indicates that this meteorite originated fiom a different type of parent body than the CM and CI chondrites. The parent body was apparently devoid of the reagents such as aldehyldes/ketones, HCN and ammonia needed for the effective abiotic synthesis of amino acids. Based on reflectance spectral measurements, Tagish Lake has been associated with P- or D-type asteroids. If the Tagish Lake meteorite was indeed derived fiom these types of parent bodies, our understanding of these primitive asteroids needs to be reevaluated with respect to their potential inventory of biologically important organic compounds.

  16. Refractory element fractionation in the Allende meteorite: Implications for solar nebula condensation and the chondritic composition of planetary bodies

    NASA Astrophysics Data System (ADS)

    Stracke, Andreas; Palme, Herbert; Gellissen, Marko; Münker, Carsten; Kleine, Thorsten; Birbaum, Karin; Günther, Detlef; Bourdon, Bernard; Zipfel, Jutta

    2012-05-01

    Chondritic meteorites represent primitive undifferentiated solar system material that is compositionally similar to the non-volatile fraction of the Sun. The mineralogy and texture of chondritic meteorites is complex, however, because they are mixtures of several components that formed under different conditions in the solar nebula and were further processed on their parent bodies: chondrules, a volatile rich, fine-grained matrix, including a variety of mineral and lithic clasts, metal, sulfides, and Ca, Al-rich inclusions (CAI). The bulk chemistry of a single aliquot of a chondritic meteorite consequently depends on the size and distribution of its constituents. Here, we investigate the effect of sample heterogeneity on the major and trace element composition of the CV chondrite Allende using a single 30 g slice, which is 22.5 cm2 in dimension and 4 mm thick. Thirty-nine equally sized pieces with an average sample weight of ca. 0.6 g (corresponding to a cube with an edge length of 5 to 6 mm) were powdered and aliquots of 0.12 g and 0.02-0.03 g were analyzed by XRF for major and ICP-MS for trace elements. One sample contained a large CAI, another sample was dominated by a dark inclusion (DI). Excluding these two samples, the concentrations of the major elements Mg, Si and Fe are constant within analytical uncertainty at the millimeter-centimeter scale (S.D. 0.9, 1.3 and 2.6%, respectively). Non-refractory minor and trace elements are similarly constant, including geochemically very different elements such as Mn, Cr, Ni, Co, P, Zn and Pb. This reflects a uniform mixture of the various host phases of these elements during accretion, and excludes elemental redistribution above a millimeter-scale by aqueous alteration and/or thermal metamorphism on the parent body. The refractory elements Al, Ca, Ti etc. are more variable (S.D. 17, 10 and 9%, respectively), which is mainly the result of different proportions of millimeter-size CAI, many of them with strongly

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

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

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

  18. The parent magma of the Nakhla (SNC) meteorite: Reconciliation of composition estimates from magmatic inclusions and element partitioning

    NASA Technical Reports Server (NTRS)

    Treiman, A. H.

    1993-01-01

    The composition of the parent magma of the Nakhla meteorite was difficult to determine, because it is accumulate rock, enriched in olivine and augite relative to a basalt magma. A parent magma composition is estimated from electron microprobe area analyses of magmatic inclusions in olivine. This composition is consistent with an independent estimate based on the same inclusions, and with chemical equilibria with the cores of Nakhla's augites. This composition reconciles most of the previous estimates of Nakhla's magma composition, and obviates the need for complex magmatic processes. Inconsistency between this composition and those calculated previously suggests that magma flowed through and crystallized into Nakhla as it cooled.

  19. Evaluating the Evidence for Magnetic Dynamocs in Chondritic Parent Bodies

    NASA Astrophysics Data System (ADS)

    Fu, R. R.; Weiss, B. P.; Krot, A. N.; Kehayias, P.; Glenn, D. R.; Fintor, K.; Pál-Molnár, E.; Bryson, J. F. J.; Walsworth, R. L.

    2016-08-01

    We present paleomagnetic data suggesting that the LL chondrite parent body lacked a magnetic dynamos. We then further test the dynamo hypothesis for the CV parent body by mapping magnetization in Kaba.

  20. 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.

  1. Extraterrestrial amino acids in Orgueil and Ivuna: Tracing the parent body of CI type carbonaceous chondrites

    PubMed Central

    Ehrenfreund, Pascale; Glavin, Daniel P.; Botta, Oliver; Cooper, George; Bada, Jeffrey L.

    2001-01-01

    Amino acid analyses using HPLC of pristine interior pieces of the CI carbonaceous chondrites Orgueil and Ivuna have found that β-alanine, glycine, and γ-amino-n-butyric acid (ABA) are the most abundant amino acids in these two meteorites, with concentrations ranging from ≈600 to 2,000 parts per billion (ppb). Other α-amino acids such as alanine, α-ABA, α-aminoisobutyric acid (AIB), and isovaline are present only in trace amounts (<200 ppb). Carbon isotopic measurements of β-alanine and glycine and the presence of racemic (D/L ≈ 1) alanine and β-ABA in Orgueil suggest that these amino acids are extraterrestrial in origin. In comparison to the CM carbonaceous chondrites Murchison and Murray, the amino acid composition of the CIs is strikingly distinct, suggesting that these meteorites came from a different type of parent body, possibly an extinct comet, than did the CM carbonaceous chondrites. PMID:11226205

  2. Tafassasset: Evidence of early incipient differentiation on a metal-rich chondritic parent body

    NASA Astrophysics Data System (ADS)

    Breton, Thomas; Quitté, Ghylaine; Toplis, Michael J.; Monnereau, Marc; Birck, Jean-Louis; Göpel, Christa; Charles, Cyril

    2015-09-01

    Tafassasset is a primitive meteorite, the origin of which is still debated. Its possible relationship to either the CR chondrites - considered among the most primitive meteorites - or the brachinites - complex primitive achondrites - makes it an interesting sample for studying the initial stages of planetary accretion and differentiation in the early solar system. Here, we report tungsten (W) isotope data for bulk rock samples as well as for mineral fractions from Tafassasset, along with micro-computed tomography of a piece of the meteorite. Silicates show mass-independent W isotope anomalies, while the metal phase does not. These nucleosynthetic anomalies are interpreted as reflecting the presence of SiC presolar grains in the matrix of the meteorite, carrying s-process184W. After correction of the nucleosynthetic anomalies, a correlation is observed between the 182W/184W isotope compositions and the Hf/W ratios of the different fractions. A 182Hf-182W age of ca. 2.9 Ma after CAIs is inferred from the 182Hf-182W chronometer, slightly older than other estimates based on the 53Mn-53Cr, 26Al-26Mg, and Pb/Pb chronometers, but consistent with the difference in closure temperatures of the different isotopic systems. Numerical modeling of the thermal evolution of Tafassasset indicates accretion of a parent-body less than ∼50 km in diameter, ≤1 Ma after the formation of CAIs, at a time when short-lived radio-nuclides induced metal-silicate separation and partial melting of the silicates with extraction of a basaltic component. According to our new data, Tafassasset may represent an inner part of a CR-like parent body, with a differentiation history similar to, but less severe than, that of brachinites.

  3. Water transport and the evolution of CM parent bodies

    NASA Astrophysics Data System (ADS)

    Coker, R.; Cohen, B.

    2014-07-01

    Extraterrestrial water-bearing minerals are of great importance both for understanding the formation and evolution of the solar system and for supporting future human activities in space. Asteroids are the primary source of meteorites, many of which show evidence of an early heating episode and varying degrees of aqueous alteration. The origin and characterization of hydrated minerals (minerals containing H_2O or OH) among both the main-belt and near-Earth asteroids is important for understanding a wide range of solar-system formation and evolutionary processes, as well as for planning for human exploration. Current hypotheses postulate asteroids began as mixtures of water ice and anhydrous silicates. A heating event early in solar-system history was then responsible for melting the ice and driving aqueous alteration. The link between asteroids and meteorites is forged by reflectance spectra, which show 3-μm bands indicative of bound OH or H_2O on the C-class asteroids, which are believed to be the parent bodies of the carbonaceous chondrites in our collections [1]. The conditions at which aqueous alteration occurred in the parent bodies of carbonaceous chondrites are thought to be well-constrained: at 0--25°C for less than 15 Myr after asteroid formation [2]. In previous models, many scenarios exhibit peak temperatures of the rock and co-existing liquid water in more than 75 % of the asteroid's volume rising to 150°C and higher[3,4], due to the exothermic hydration reactions triggering a thermal runaway effect. However, even in a high-porosity, water-saturated asteroid, very limited liquid water flow is predicted (distances of 100's μ m at most) [5]. This contradiction has yet to be resolved. Still, it may be possible for water to become liquid even in the near-surface environment, for a long enough time to drive aqueous alteration before vaporizing or freezing then subliming. Thus, we are using physics- and chemistry-based models that include thermal and

  4. 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.

  5. The histories of ordinary chondrite parent bodies - U, Th-He age distributions

    SciTech Connect

    Wasson, J.T.; Wang, Sichao Purple Mountain Observatory, Nanjing )

    1991-06-01

    Age patterns observed in meteorite groups reflect the different thermal or impact histories experienced by their parent bodies. To assess the number of ordinary chondrite (OC) parent bodies, rare-gas data in the Schultz and Kruse (1989) data base were used to calculate U, Th-He gas-retention ages. Most H- and LL-chondrite ages are high; about 81 percent are greater than 2.2 Ga. In contrast, most L-chondrite ages are low; about 69 percent are not greater than 2.2 Ga, and about 35 percent are not greater than 0.9 Ga. The latter fraction is substantially lower than the value of 44 percent given by Heymann (1967). The difference is attributed to the preferential inclusion of shocked L chondrites in early studies. Broad age peaks in the H and LL groups near 3.4 Ga probably reflect thermal loss during metamorphism, but in the H distribution there is a hint of minor outgassing 'events' near 1 Ga. The L/LL chondrites have chemical properties intermediate between and unresolvable from L and LL chondrites. The high ages of most L/LL chondrites are evidence against these originating on the L parent body; the L/LL age distribution is consistent with an origin on the LL parent body or on an independent body. 22 refs.

  6. The histories of ordinary chondrite parent bodies - U, Th-He age distributions

    NASA Astrophysics Data System (ADS)

    Wasson, John T.; Wang, Sichao

    1991-06-01

    Age patterns observed in meteorite groups reflect the different thermal or impact histories experienced by their parent bodies. To assess the number of ordinary chondrite (OC) parent bodies, rare-gas data in the Schultz and Kruse (1989) data base were used to calculate U, Th-He gas-retention ages. Most H- and LL-chondrite ages are high; about 81 percent are greater than 2.2 Ga. In contrast, most L-chondrite ages are low; about 69 percent are not greater than 2.2 Ga, and about 35 percent are not greater than 0.9 Ga. The latter fraction is substantially lower than the value of 44 percent given by Heymann (1967). The difference is attributed to the preferential inclusion of shocked L chondrites in early studies. Broad age peaks in the H and LL groups near 3.4 Ga probably reflect thermal loss during metamorphism, but in the H distribution there is a hint of minor outgassing "events" near 1 Ga. The L/LL chondrites have chemical properties intermediate between and unresolvable from L and LL chondrites. The high ages of most L/LL chondrites are evidence against these originating on the L parent body; the L/LL age distribution is consistent with an origin on the LL parent body or on an independent body.

  7. Restriction of parent body heating by metal-troilite melting: Thermal models for the ordinary chondrites

    NASA Astrophysics Data System (ADS)

    Mare, Eleanor R.; Tomkins, Andrew G.; Godel, Belinda M.

    2014-04-01

    Ordinary chondrite meteorites contain silicates, Fe,Ni-metal grains, and troilite (FeS). Conjoined metal-troilite grains would be the first phase to melt during radiogenic heating in the parent body, if temperatures reached over approximately 910-960 °C (the Fe,Ni-FeS eutectic). On the basis of two-pyroxene thermometry of 13 ordinary chondrites, we argue that peak temperatures in some type 6 chondrites exceeded the Fe,Ni-FeS eutectic and thus conjoined metal-troilite grains would have begun to melt. Melting reactions consume energy, so thermal models were constructed to investigate the effect of melting on the thermal history of the H, L, and LL parent asteroids. We constrained the models by finding the proportions of conjoined metal-troilite grains in ordinary chondrites using high-resolution X-ray computed tomography. The models show that metal-troilite melting causes thermal buffering and inhibits the onset of silicate melting. Compared with models that ignore the effect of melting, our models predict longer cooling histories for the asteroids and accretion times that are earlier by 61, 124, or 113 kyr for the H, L, and LL asteroids, respectively. Because the Ni/Fe ratio of the metal and the bulk troilite/metal ratio is higher in L and LL chondrites than H chondrites, thermal buffering has the greatest effect in models for the L and LL chondrite parent bodies, and least effect for the H chondrite parent. Metal-troilite melting is also relevant to models of primitive achondrite parent bodies, particularly those that underwent only low degrees of silicate partial melting. Thermal models can predict proportions of petrologic types formed within an asteroid, but are systematically different from the statistics of meteorite collections. A sampling bias is interpreted to explain these differences.

  8. Numerical Simulation of Hydrothermal Convection in Chondritic Parent Bodies

    NASA Astrophysics Data System (ADS)

    Schubert, G.; Travis, B. J.

    2004-11-01

    Chondritic meteorites are so named because they nearly all contain chondrules - small spherules of olivine and pyroxene that condensed and crystallized in the solar nebula and then combined with other material to form a matrix. Their parent bodies did not differentiate, i.e., form a crust and a core. Carbonaceous chondrites (CCs) derived from undifferentiated icy planetesimals. CCs exhibit liquid water-rock interactions. CCs contain small but significant amounts of radiogenic elements (e.g., 26Al), sufficient to warm up an initially cold planetesimal. A warmed-up phase could last millions of years. During the warmed-up phase, liquid water will form, and could evolve into a hydrothermal convective flow. Flowing water will affect the evolution of minerals. We report on results of a numerical study of the thermal evolution of CCs, considering the major factors that control heating history and possible flow, namely: permeability, radiogenic element content, and planetesimal radius. We determine the time sequence of thermal processes, length of time for a convective phase and patterns of flow, amount of fluid flow throughout the planetesimals, and sensitivity of evolution to primary parameters. We use the MAGHNUM code to simulate 3-D dynamic freezing and thawing and flow of water in a self-gravitating, permeable spherical body. Governing equations are Darcy's law, mass conservation, energy conservation, and the equation of state for water, ice and vapor mixtures. We have simulated the evolution of heating, melting of ice, subsequent flow and eventual re-freezing for several examples of carbonaceous chondrite planetesimals. We have demonstrated that hydrothermal convection should occur for a range of parameter values and would last for several millions of years. Roughly half the interior of simulated planetesimals experience water fluxes of 100--200 pore volumes. High pore volume flux facilitates extensive chemical reactions.

  9. Evolution of the Ureilite Parent Body

    NASA Technical Reports Server (NTRS)

    Hudson, P.; Romanek, C.; Paddock, Lindy; Mittlefehldt, D. W.

    2004-01-01

    Ureilites are ultramafic achondrites composed primarily of olivine and pyroxene with intergranular fine-grained metal, sulfides, and silicates. Ureilites contain significant amounts of carbon (up to about 6.5 wt%) as graphite, lonsdaleite, and/or diamond. It has been shown that carbon-silicate redox (i.e. "smelting") reactions are responsible for the negative FeO-MnO (or positive Fe/Mn-Fe/Mg with constant Mn/Mg) trend seen in the mineral and bulk compositions of ureilites and for the positive correlation between modal percent pigeonite and mg#. Carbon redox reactions are strongly exothermic and pressure dependent; so ureilites with the largest mg# are the most reduced, experienced the highest temperatures, and formed at the lowest pressures, i.e. near the surface of the ureilite parent body. Ureilites with the largest mg# have the smallest the delta(sup 18)O and the largest Delta(sup 17)O. To explain this, Singletary and Grove proposed that heterogeneous accretion took place on the ureilite parent body, which lead to a radial distribution of the oxygen isotopes. To further investigate possible relationships, we performed carbon isotope and electron probe measurements on a suite of 27 ureilites in order to see the type of correlation that exists between mg#, oxygen isotopes, and carbon.

  10. Hf-W chronometry of core formation in planetesimals inferred from weakly irradiated iron meteorites

    NASA Astrophysics Data System (ADS)

    Kruijer, Thomas S.; Sprung, Peter; Kleine, Thorsten; Leya, Ingo; Burkhardt, Christoph; Wieler, Rainer

    2012-12-01

    The application of Hf-W chronometry to determine the timescales of core formation in the parent bodies of magmatic iron meteorites is severely hampered by 182W burnout during cosmic ray exposure of the parent meteoroids. Currently, no direct method exists to correct for the effects of 182W burnout, making the Hf-W ages for iron meteorites uncertain. Here we present noble gas and Hf-W isotope systematics of iron meteorite samples whose W isotopic compositions remained essentially unaffected by cosmic ray interactions. Most selected samples have concentrations of cosmogenic noble gases at or near the lowermost level observed in iron meteorites and, for iron meteorite standards, have very low noble gas and radionuclide based cosmic ray exposure ages (<60 Ma). In contrast to previous studies, no corrections of measured W isotope compositions are required for these iron meteorite samples. Their ɛ182W values (parts per 104 deviations from the terrestrial value) are higher than those measured for most other iron meteorites and range from -3.42 to -3.31, slightly elevated compared to the initial 182W/184W of Ca-Al-rich Inclusions (CAI; ɛ182W = -3.51 ± 0.10). The new W isotopic data indicate that core formation in the parent bodies of the IIAB, IIIAB, and IVA iron meteorites occurred ˜1-1.5 Myr after CAI formation (with an uncertainty of ˜1 Myr), consistent with earlier conclusions that the accretion and differentiation of iron meteorite parent bodies predated the accretion of most chondrite parent bodies. One ungrouped iron meteorite (Chinga) exhibits small nucleosynthetic W isotope anomalies, but after correction for these anomalies its ɛ182W value agrees with those of the other samples. Another ungrouped iron (Mbosi), however, has elevated ɛ182W relative to the other investigated irons, indicating metal-silicate separation ˜2-3 Myr later than in the parent bodies of the three major iron meteorite groups studied here.

  11. 182Hf- 182W chronometry and early differentiation of the ureilite parent body

    NASA Astrophysics Data System (ADS)

    Lee, Der-Chuen; Halliday, Alex N.; Singletary, Steven J.; Grove, Timothy L.

    2009-11-01

    Eight samples spanning the bulk chemical range of monomict ureilites, have been analyzed for their W isotopic composition and Hf/W in order to elucidate the differentiation history of the ureilite parent body. The ureilites studied here show sub-chondritic Hf and W concentrations and low Hf/W ratio, and all show clear 182W deficits relative to bulk chondrites. The W isotope data provide evidence that the ureilite parent body differentiated within 1 to 2 million years after the start of the solar system. Such early accretion and differentiation is comparable to the parent bodies of various magmatic iron meteorites, as well as the HED parent body. However, the trace element fractionations and by inference melting processes are very different. An early smelting/partial melting event coupled with metal-silicate segregation, however, can reproduce the observed Hf-W data in ureilites, and is consistent with petrological and other chemical evidence for a missing basaltic component and with primitive oxygen and noble gases compositions.

  12. Could G Asteroids be the Parent Bodies of the CM Chondrites?

    NASA Astrophysics Data System (ADS)

    Burbine, T. H.; Binzel, R. P.

    1995-09-01

    Since almost all meteorites are believed to be derived from asteroidal source bodies, the comparison of asteroid and meteorite spectra should allow for possible meteorite parent bodies to be identified. However only two asteroids with unique spectral characteristics, 4 Vesta with the basaltic achondrites [1] and near-Earth asteroid 3103 Eger with the aubrites [2], have been convincingly linked with any meteorite type. Farinella et al. [3] has done a study of 2355 numbered main-belt asteroids to determine which asteroids have the highest probability of having their fragments injected into the 3:1 mean motion and the nu6 secular resonance regions. Interestingly, asteroids with the third (19 Fortuna), tenth (1 Ceres) and eleventh (13 Egeria) highest theoretical total fragment delivery efficiencies are G-asteroids, a moderately rare type of asteroid with approximately ten known members. (Vesta has the fifth highest theoretical total fragment delivery efficiency.) G-asteroids tend to have the strongest ultraviolet, 0.7 micrometers and 3 micrometers absorption features of all C-type (B, C, F and G) asteroids, appearing to indicate that G-asteroids are at the upper range of the aqueous alteration sequence in the asteroid population. (The 0.7 micrometers feature is apparently due to iron oxides in hydrated silicates and the 3 micrometers feature is apparently due to hydrated minerals.) Meteorites that have reflectance spectra with a 3 micrometers feature of comparable intensity to those of the G-asteroids are the CI, CM and CR chondrites. However, G-asteroids (like all C-types) have ultraviolet absorption features that are weaker than previously measured meteorite spectra. Comparisons of reflectance spectra between Ceres and meteorite samples appear to indicate that Ceres is compositionally different from almost all known carbonaceous chondrites. Both Fortuna and Egeria have an absorption feature centered around 0.7 micrometers [4] that is similar in structure and strength

  13. Fossil Meteorite Unearthed From Crater

    NASA Astrophysics Data System (ADS)

    Martel, L. M. V.

    2006-06-01

    A team of scientists lead by Wolf Maier (University of Quebec, Canada and University of Pretoria, South Africa and soon at University of Western Australia, Perth) and Marco Andreoli (University of the Witwatersrand and South African Nuclear Energy Corp.) and colleagues who also hail from Canada, South Africa, the United Kingdom, and the United States, have announced the discovery of a 25-centimeter-wide chondritic meteorite unearthed from the 145-million-year-old Morokweng impact crater in South Africa. Found within the crater's impact melt sheet about 770 meters (half a mile) down a drilling borehole, the hefty meteorite's existence would seem improbable given its low chance of surviving the high shock pressures and temperatures normally associated with large impact events. Its unusual composition could mean it is a sample from a previously unknown part of the LL chondrite parent body or maybe it is from an entirely different asteroid population than other known meteorites.

  14. Parental consent and the use of dead children's bodies.

    PubMed

    Wilkinson, T M

    2001-12-01

    It has recently become known that, in Liverpool and elsewhere, parts of children's bodies were taken postmortem and used for research without the parents being told. But should parental consent be sought before using children's corpses for medical purposes? This paper presents the view that parental consent is overrated. Arguments are rejected for consent from dead children's interests, property rights, family autonomy, and religious freedom. The only direct reason to get parental consent is to avoid distressing the parents, which carries implications for the consent process, secret harvesting of body parts, and the weight to be given to parental feelings.

  15. A Cometary Origin of the Amino Acids in the Orgueil Meteorite?

    NASA Technical Reports Server (NTRS)

    Botta, O.; Ehrenfreund, P.; Glavin, D. P.; Cooper, G. W.; Kminek, G.; Bada, J. L.

    2000-01-01

    A reexamination of a piece of the Orgueil meteorite revealed that its amino acid composition is strikingly different to two other carbonaceous chondrites, suggesting different parent bodies. A cometary origin for Orgueil would be one possibility.

  16. Chiral Biomarkers in Meteorites

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.

    2010-01-01

    The chirality of organic molecules with the asymmetric location of group radicals was discovered in 1848 by Louis Pasteur during his investigations of the rotation of the plane of polarization of light by crystals of sodium ammonium paratartrate. It is well established that the amino acids in proteins are exclusively Levorotary (L-aminos) and the sugars in DNA and RNA are Dextrorotary (D-sugars). This phenomenon of homochirality of biological polymers is a fundamental property of all life known on Earth. Furthermore, abiotic production mechanisms typically yield recemic mixtures (i.e. equal amounts of the two enantiomers). When amino acids were first detected in carbonaceous meteorites, it was concluded that they were racemates. This conclusion was taken as evidence that they were extraterrestrial and produced by abiologically. Subsequent studies by numerous researchers have revealed that many of the amino acids in carbonaceous meteorites exhibit a significant L-excess. The observed chirality is much greater than that produced by any currently known abiotic processes (e.g. Linearly polarized light from neutron stars; Circularly polarized ultraviolet light from faint stars; optically active quartz powders; inclusion polymerization in clay minerals; Vester-Ulbricht hypothesis of parity violations, etc.). This paper compares the measured chirality detected in the amino acids of carbonaceous meteorites with the effect of these diverse abiotic processes. IT is concluded that the levels observed are inconsistent with post-arrival biological contamination or with any of the currently known abiotic production mechanisms. However, they are consistent with ancient biological processes on the meteorite parent body. This paper will consider these chiral biomarkers in view of the detection of possible microfossils found in the Orgueil and Murchison carbonaceous meteorites. Energy dispersive x-ray spectroscopy (EDS) data obtained on these morphological biomarkers will be

  17. Meteorite craters

    NASA Technical Reports Server (NTRS)

    Ivanov, B. A.; Bazilevskiy, A. T.

    1986-01-01

    The origin and formation of various types of craters, both on the Earth and on other planetary bodies, are discussed. Various models are utilized to depict various potential causes of the types and forms of meteorite craters in our solar system, and the geological structures are also discussed.

  18. Magnetite in CI carbonaceous meteorites - Origin by aqueous activity on a planetesimal surface

    NASA Technical Reports Server (NTRS)

    Kerridge, J. F.; Mackay, A. L.; Boynton, W. V.

    1979-01-01

    The composition and morphology of magnetite in CI carbonaceous meteorites appear incompatible with a nebular origin. Mineralization on the meteorite parent body is a more plausible mode of formation. The iodine-xenon age of this material therefore dates an episode of secondary mineralization on a planetesimal rather than the epoch of condensation in the primitive solar nebula.

  19. Sutter's Mill dicarboxylic acids as possible tracers of parent-body alteration processes

    NASA Astrophysics Data System (ADS)

    Pizzarello, Sandra; Garvie, Laurence A. J.

    2014-11-01

    Dicarboxylic acids were searched for in three Sutter's Mill (SM) fragments (SM2 collected prerain, SM12, and SM41) and found to occur almost exclusively as linear species of 3- to 14-carbon long. Between these, concentrations were low, with measured quantities typically less than 10 nmole g-1 of meteorite and a maximum of 6.8 nmole g-1 of meteorite for suberic acid in SM12. The SM acids' molecular distribution is consistent with a nonbiological origin and differs from those of CMs, such as Murchison or Murray, and of some stones of the C2-ungrouped Tagish Lake meteorite, where they are abundant and varied. Powder X-ray diffraction of SM12 and SM41 show them to be dominated by clays/amorphous material, with lesser amounts of Fe-sulfides, magnetite, and calcite. Thermal gravimetric (TG) analysis shows mass losses up to 1000 °C of 11.4% (SM12) and 9.4% (SM41). These losses are low compared with other clay-rich carbonaceous chondrites, such as Murchison (14.5%) and Orgueil (21.1%). The TG data are indicative of partially dehydrated clays, in accordance with published work on SM2, for which mineralogical studies suggest asteroidal heating to around 500 °C. In view of these compositional traits and mineralogical features, it is suggested that the dicarboxylic acids observed in the SM fragments we analyzed likely represent a combination of molecular species original to the meteorite as well as secondary products formed during parent-body alteration processes, such as asteroidal heating.

  20. 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.

  1. Electrical conductivity of chondritic meteorites

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  2. Annual Occurrence of Meteorite-Dropping Fireballs

    NASA Astrophysics Data System (ADS)

    Konovalova, Natalia; Jopek, Tadeusz J.

    2016-07-01

    The event of Chelyabinsk meteorite has brought about change the earlier opinion about limits of the sizes of potentially dangerous asteroidal fragments that crossed the Earth's orbit and irrupted in the Earth's atmosphere making the brightest fireball. The observations of the fireballs by fireball networks allows to get the more precise data on atmospheric trajectories and coordinates of predicted landing place of the meteorite. For the reason to search the periods of fireball activity is built the annual distribution of the numbers of meteorites with the known fall dates and of the meteorite-dropping fireballs versus the solar longitude. The resulting profile of the annual activity of meteorites and meteorite-dropping fireballs shows several periods of increased activity in the course of the year. The analysis of the atmospheric trajectories and physical properties of sporadic meteorite-dropping fireballs observed in Tajikistan by instrumental methods in the summer‒autumn periods of increased fireballs activity has been made. As a result the structural strength, the bulk density and terminal mass of the studied fireballs that can survive in the Earth atmosphere and became meteorites was obtained. From the photographic IAU MDC_2003 meteor database and published sources based on the orbit proximity as determined by D-criterion of Southworth and Hawkins the fireballs that could be the members of group of meteorite-dropping fireballs, was found. Among the near Earth's objects (NEOs) the searching for parent bodies for meteorite-dropping fireballs was made and the evolution of orbits of these objects in the past on a long interval of time was investigated.

  3. A petrogenetic model of the relationships among achondritic meteorites

    NASA Technical Reports Server (NTRS)

    Stolper, E.; Hays, J. F.; Mcsween, H. Y., Jr.

    1979-01-01

    Petrological evidence is used to support the hypothesis that although the magma source regions and parent bodies of basaltic achondrite, shergottite, nakhlite, and chassignite meteorites are clearly distinct, they may be simply related. It is proposed that the peridotites which on partial melting generated the parent magmas of the shergottite meteorites differed from those which gave rise to eucritic magmas by being enriched in a component rich in alkalis and other volatiles. Similarly, the source regions of the parent magmas of the nakhlite and chassignite meteorites differed from those on the shergottite parent body by being still richer in this volatile-rich component. These regions could have been related by processes such as mixture of variable amounts of volatile-rich and volatile-poor components in planetary or nebular settings, or alternatively by variable varying degrees of volatile loss from volatile-rich materials.

  4. Imino Acids in the Murchison Meteorite: Evidence of Strecker Reactions

    NASA Technical Reports Server (NTRS)

    Lerner, N. R.; Cooper, G. W.

    2003-01-01

    Both alpha-amino acids and alpha-hydroxy acids occur in aqueous extracts of the Murchison carbonaceous meteorite. The Strecker-cyanohydrin reaction, the reaction of carbonyl compounds, cyanide, and ammonia to produce amino and hydroxy acids, has been proposed as a source of such organic acids in meteorites. Such syntheses are consistent with the suggestion that interstellar precursors of meteoritic organic compounds accreted on the meteorite parent body together with other ices. Subsequent internal heating of the parent body melted these ices and led to the formation of larger compounds in synthetic reactions during aqueous alteration, which probably occurred at temperatures between 273K and 298K. In the laboratory, imino acids are observed as important by-products of the Strecker synthesis.

  5. Generating a characterization method utilizing the visible (0.6-1.0 mu m) peak feature to aid in identification of ordinary chondrite parent bodies

    NASA Astrophysics Data System (ADS)

    Johnson, Cassandra Lynne

    Surveys in the visible to near infrared (VNIR) of main belt asteroids which cut off at the 1 micron wavelength prevent adequate characterization for approximately 2500 asteroids. This project aims at surveying spectral data from RELAB and Gaffey's meteorite datasets utilizing the peak feature located between charge transfer and Band I of 224 ordinary chondrite (OC) samples to analyze the peak position shifts with respect to subtypes H-, L- and LL- to generate a new characterization method. This method may make it possible to unite the datasets between the meteorites and asteroids to further constrain and characterize the OC parent bodies.

  6. Carboxylic Acids as Indicators of Parent Body Conditions

    NASA Astrophysics Data System (ADS)

    Lerner, N. R.

    1995-09-01

    Alpha-hydroxy and alpha-amino carboxylic acids found on the Murchison meteorite are deuterium enriched [1]. It is postulated that they arose from a common interstellar source: the reaction of carbonyl compounds in an aqueous mixture containing HCN and NH3. Carbonyl compounds react with HCN to form alph-hydroxy nitriles, RR'CO + HCN <--> RR'C(OH)CN. If ammonia is also present, the alpha-hydroxy nitriles will exist in equilibirum with the alpha-amino nitriles, RR'C(OH)CN +NH3 .<--> RRCNH2CN + H2O. Both nitriles are hydrolyzed by water to form carboxylic acids: RR'C(OH)CN + H2O --> RR'C(OH)CO2H and RR'C(NH2)CN + H2O --> RR'C(NH2)CO2H. Carbonyl compounds observed in the interstellar medium have been shown to be deuterium enriched [2]. The combined alpha-amino acids found on Murchison have deltaD = +1751 o/oo while the combined alpha-hydroxy acids have deltaD = +573. o/oo [1]. This large discrepancy in deltaD values does not preclude common precursors for the alpha-amino acids and the alpha-hydroxy acids. Different relative amounts of specific alpha-amino and alpha-hydroxy acids could lead to quite different combined D/H ratios. If the alpha-hydroxy acids lose significantly more deuterium during synthesis than the alpha-amino acids or if they have a higher rate of H/D exchange with liquid water than alpha-amino acids, the alpha-hydroxy acids would be isotopically lighter than the alpha-amino acids, because the water responsible for the aqueous alteration of the Murchison parent body was deuterium depleted with deltaD = -100. o/oo [3]. To determine between these alternative mechanisms we measured the rates of hydrogen-deuterium exchange of glycolic acid (the alpha-hydroxy analog of glycine), lactic acid (the alpha-hydroxy analog of alanine), and alpha-hydroxy isobutyric acid have been measured in D2O as a function of pH, temperature and the presence of Allende or Murchison minerals. No detectable H/D exchange was observed. Glycine subjected to similar conditons exchanged

  7. Body Talk for Parents of Girls.

    ERIC Educational Resources Information Center

    Stubbs, Margaret L.

    This pamphlet, targeted to girls' parents, discusses issues surrounding puberty. The introduction discusses cultural images of menstruation and girls' attitudes towards it. Suggestions are offered for discussing menstruation with one's daughter. Suggestions focus on timing of introducing the topic; which parent takes responsibility for menstrual…

  8. Body Talk for Parents of Boys.

    ERIC Educational Resources Information Center

    Stubbs, Margaret L.

    This pamphlet, targeted to boys' parents, discusses issues surrounding puberty. The introduction discusses education about menstruation and girls' and boys' attitudes towards it. Suggestions are offered for discussing menstruation with one's son. Suggestions focus on timing of introducing the topic; which parent takes responsibility for menstrual…

  9. 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.

  10. Iron and Stony-iron Meteorites

    NASA Astrophysics Data System (ADS)

    Haack, H.; McCoy, T. J.

    2003-12-01

    Without iron and stony-iron meteorites, our chances of ever sampling the deep interior of a differentiated planetary object would be next to nil. Although we live on a planet with a very substantial core, we will never be able to sample it. Fortunately, asteroid collisions provide us with a rich sampling of the deep interiors of differentiated asteroids.Iron and stony-iron meteorites are fragments of a large number of asteroids that underwent significant geological processing in the early solar system. Parent bodies of iron and some stony-iron meteorites completed a geological evolution similar to that continuing on Earth - although on much smaller length- and timescales - with melting of the metal and silicates, differentiation into core, mantle, and crust, and probably extensive volcanism. Iron and stony-iron meteorites are our only available analogues to materials found in the deep interiors of Earth and other terrestrial planets. This fact has been recognized since the work of Chladni (1794), who argued that stony-iron meteorites must have originated in outer space and fallen during fireballs and that they provide our closest analogue to the material that comprises our own planet's core. This chapter deals with our current knowledge of these meteorites. How did they form? What can they tell us about the early evolution of the solar system and its solid bodies? How closely do they resemble the materials from planetary interiors? What do we know and don't we know?Iron and stony-iron meteorites constitute ˜6% of meteorite falls (Grady, 2000). Despite their scarcity among falls, iron meteorites are our only samples of ˜75 of the ˜135 asteroids from which meteorites originate ( Keil et al., 1994; Scott, 1979; Meibom and Clark, 1999; see also Chapter 1.05), suggesting that both differentiated asteroids and the geologic processes that produced them were common.Despite the highly evolved nature of iron and stony-iron meteorites, their chemistry provides important

  11. Lunar Cataclysm from the Break-Up of the Mesosiderite Parent Body

    NASA Astrophysics Data System (ADS)

    Cuk, Matija

    2010-05-01

    New interpretations of crater size-distribution (Cuk et al. 2010) and remnant basin magnetization (Mohit et al. 2010) point to a break in lunar cratering history close to the end of the Nectarian period. In this view, almost all Nectarian basins formed much before 3.9 Gyr ago, possible even before 4.2 Gyr ago (in agreement with recent re-evaluation of the Apollo 16 samples; Norman et al. 2010). More recent basins (including Imbrium) appear to have formed in a short-lived bombardment spike (the "true" lunar cataclysm) following a period of lower impact activity. The size distribution of these Imbrian impactors was unlike that of main-belt asteroids, which appear to have dominated Nectarian and pre-Nectarian impacts. As this spike was not caused by any known small body population, we favor its origin in a tidal break-up of a single large body in the terrestrial planet region. Existence of an additional D>400 km asteroidal body that was still intact until at least 3.9 Gyr ago has already been suggested based on the cooling histories of mesosiderite meteorites (Haack et al. 1996, Bogard and Garrison 1998). We propose that the mesosiderite parent body resided in the region between Mars and the asteroid belt for hundreds of Myrs, only to be destabilized and tidally disrupted by a terrestrial planet (cf. Chambers 2007). While most of this body's fragments would impact the Sun and the planets, some may have chaotically diffused into stable orbits to become intermediate parent bodies of mesosiderites. Both the survival of mesosiderite fragments and the complete extinction of the low-i trans-Martian population both point to a relatively high early eccentricity of Mars, which has since decreased due to global chaos. We expect that the present-day direct parent of mesosiderites is most likely in or close to the Hungaria high-inclination asteroid group.

  12. Thin-sectioning and analysis of fine-grained meteoritic materials

    NASA Technical Reports Server (NTRS)

    Brooks, Donald A. (Editor); Bradley, John P.

    1992-01-01

    The overall theme of the work was the identification of the sources and formation/aggregation mechanisms of the various classes of interplanetary dust particles (IDP's) and to clarify the relationship between IDP's and conventional meteorites. IDP's are believed to be derived from a much broader range of parent bodies than conventional meteorites. Some of these parent bodies (e.g., comets) have escaped that post accretional processing that has affected the parent bodies of meteorites. Therefore, IDP's are likely to preserve a record of early solar system and possibly presolar grain forming reactions. Using analytical electron microscopy (AEM) and more recently micro-infrared (IR) microspectroscopy to examine ultramicrotomed thin sections, we have addressed the questions of IDP formation mechanisms, sources, and their relationship to conventional meteorites. The following sections describe specific findings resulting from these studies.

  13. Evidence for a dynamo in the main group pallasite parent body.

    PubMed

    Tarduno, John A; Cottrell, Rory D; Nimmo, Francis; Hopkins, Julianna; Voronov, Julia; Erickson, Austen; Blackman, Eric; Scott, Edward R D; McKinley, Robert

    2012-11-16

    Understanding the origin of pallasites, stony-iron meteorites made mainly of olivine crystals and FeNi metal, has been a vexing problem since their discovery. Here, we show that pallasite olivines host minute magnetic inclusions that have favorable magnetic recording properties. Our paleointensity measurements indicate strong paleomagnetic fields, suggesting dynamo action in the pallasite parent body. We use these data and thermal modeling to suggest that some pallasites formed when liquid FeNi from the core of an impactor was injected as dikes into the shallow mantle of a ~200-kilometer-radius protoplanet. The protoplanet remained intact for at least several tens of millions of years after the olivine-metal mixing event.

  14. Early Petrogenesis and Late Impact(?) Metamorphism on the GRA 06128/9 Parent Body

    NASA Technical Reports Server (NTRS)

    Nyquist, Laurence E.; Shih, C.-Y.; Reese, Y. D.

    2009-01-01

    Initial studies of GRA06128 and GRA06129 (hereafter GRA 8 and GRA 9) suggested that these alkalic meteorites represent partial melts of a parent body of approximately chondritic composition. A SM-147-Nd-143 isochron age of 4.545 +/- 0.087 Ga was found for GRA 8, but plagioclase (oligoclase) plus whole rock and leachate samples gave an apparent secondary age of approximately 3.5 Ga. The approximately 4.54 Ga age was interpreted to be the crystallization age of GRA 8; the approximately 3.5 Ga as an upper limit to a time of metamorphism. Here we extend Sm-Nd and Rb-Sr analyses to GRA 9.

  15. Siderophile Element Profile Measurements in Iron Meteorites Using Laser Ablation ICP-MS

    NASA Technical Reports Server (NTRS)

    Watson, H. C.; Watson, E. B.; McDonough, W. F.

    2005-01-01

    Understanding the behaviour of siderophile elements during cooling of iron meteorites can lead to insight into the general thermal histories of the meteorites as well as their respective parent bodies. Traditionally trace element analyses in meteorites have been done using techniques that only measure the average concentration in each phase. With these methods, all of the spatial information with respect to the distribution of an element within one phase is lost. Measuring concentration profiles of trace elements in meteorites is now possible, with the advent of high-resolution analytical techniques such as laser ablation, inductively coupled plasma mass spectrometry (LA-ICP-MS) with spatial resolution <20 microns. [e.g. 1,2] and secondary ion mass spectrometry [3]. These profiles can give more insight into both the partitioning and diffusive behavior of siderophile elements in metal systems relevant to iron meteorites, as well as parent body cooling rates.

  16. The Mazapil meteorite: From paradigm to periphery

    NASA Astrophysics Data System (ADS)

    Beech, Martin

    2002-05-01

    The remarkable fact about the Mazapil meteorite is that it fell on the same night, in 1885, that the Andromedid meteor shower underwent a spectacular outburst. The simultaneity of these two events has driven speculation ever since. From circa 1886 to circa 1950 the circumstances of the Mazapil fall were taken, by a number of researchers, as the paradigm that demonstrated the fact that comets were actually swarms of meteoritic boulders. Beginning circa 1950, however, most researchers began to adopted the stance that the timing of the Mazapil fall was nothing more than pure coincidence. The reason behind this change in interpretation stemmed from, amongst other factors, the fact that none of the prominent annual meteor showers could be clearly shown to deliver meteorites. Also, with the introduction of the icy-conglomerate model for cometary nuclei, by F. Whipple in the early 1950s, it became increasingly clear that only exceptional circumstances would allow for the presence of large meteoritic bodies in cometary streams. Further, by the mid 1960s it had been shown that meteorites could, in fact, be delivered to the Earth from the main belt asteroid region via gravitational resonances. With the removal of the dynamical 'barrier' against the delivery of meteorites from the asteroid region, the idea that the Mazapil meteorite could have been part of the Andromedid stream fell into complete disfavor. This being said, we nonetheless present the results of a study concerning the possible properties of the parent object to the Mazapil meteorite based upon the assumption that it was a member of the Andromedid stream. This study is presented to illustrate the point that while cometary showers do not yield meteorites on the ground, this does not, in fact, substantiate the argument that no meteoritic bodies reside in cometary streams. Indeed, we find no good reason to suppose that an object with the characteristics of the Mazapil meteorite could not have been delivered from

  17. Thermal history of the parent bodies of asteroid Itokawa

    NASA Astrophysics Data System (ADS)

    Wakita, S.; Nakamura, T.; Ikeda, T.; Yurimoto, H.

    2014-07-01

    Introduction: The Hayabusa spacecraft collected dust particles from asteroid 25143 Itokawa. The mineralogic studies of Itokawa dust particles revealed that those dust particles resemble LL5 and/or LL6 type ordinary chondrites [1-3]. Those particles were thermally metamorphosed at a peak temperature around 800° C but did not experience temperatures over 1000° C [1]. The ^{26}Al-^{26}Mg age study and oxygen thermometry indicated that the parent body of Itokawa kept at 700° C or higher at 7.6 Myr after the Ca-Al rich inclusion (CAI) formation [2,3]. Methods: We investigated numerically the thermal modeling of the parent bodies of Itokawa which are in agreement with the mineralogic and isotopic evidence from the dust particles of Itokawa. We assumed that the parent body of Itokawa is an instantaneously-accreted spherically symmetric body and the initial temperature of the body is -73° C (200K), which is the temperature at ˜ 2 au in the solar nebula [4]. The physical properties (e.g., density, thermal conductivity) of the parent body are assumed to be the same with those of LL6 chondrites based on the analyses of the Itokawa sample [1, 2]. The main heat source is the decay energy of ^{26}Al, as used in most of the previous thermal modeling works [e.g., 5]. The one-dimensional heat conduction equations are numerically solved using a finite difference method and an explicit method of time integration (see [6] for details of the numerical methods). Numerical simulations are performed for parent bodies which have various sizes and accretion times (i.e. the initial ratio of ^{26}Al/^{27}Al). Results: Our numerical results showed that the parent bodies that accreted within 2.2 Myr after CAI formation could reach 800° at the center of the body: those bodies could be the parent bodies of Itokawa. If the parent bodies accreted within 1.9 Myr after CAI formation, the peak temperature exceeds 1000° C: those bodies could not be the parent body of Itokawa. The parent bodies

  18. 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.

  19. Origin of igneous meteorites and differentiated asteroids

    NASA Astrophysics Data System (ADS)

    Scott, E.; Goldstein, J.; Asphaug, E.; Bottke, W.; Moskovitz, N.; Keil, K.

    2014-07-01

    Introduction: Igneously formed meteorites and asteroids provide major challenges to our understanding of the formation and evolution of the asteroid belt. The numbers and types of differentiated meteorites and non-chondritic asteroids appear to be incompatible with an origin by fragmentation of numerous Vesta-like bodies by hypervelocity impacts in the asteroid belt over 4 Gyr. We lack asteroids and achondrites from the olivine-rich mantles of the parent bodies of the 12 groups of iron meteorites and the ˜70 ungrouped irons, the 2 groups of pallasites and the 4--6 ungrouped pallasites. We lack mantle and core samples from the parent asteroids of the basaltic achondrites that do not come from Vesta, viz., angrites and the ungrouped eucrites like NWA 011 and Ibitira. How could core samples have been extracted from numerous differentiated bodies when Vesta's basaltic crust was preserved? Where is the missing Psyche family of differentiated asteroids including the complementary mantle and crustal asteroids [1]? Why are meteorites derived from far more differentiated parent bodies than chondritic parent bodies even though C and S class chondritic asteroids dominate the asteroid belt? New paradigm. Our studies of meteorites, impact modeling, and dynamical studies suggest a new paradigm in which differentiated asteroids accreted at 1--2 au less than 2 Myr after CAI formation [2]. They were rapidly melted by 26Al and disrupted by hit-and-run impacts [3] while still molten or semi-molten when planetary embryos were accreting. Metallic Fe-Ni bodies derived from core material cooled rapidly with little or no silicate insulation less than 4 Myr after CAI formation [4]. Fragments of differentiated planetesimals were subsequently tossed into the asteroid belt. Meteorite evidence for early disruption of differentiated asteroids. If iron meteorites were samples of Fe-Ni cores of bodies that cooled slowly inside silicate mantles over ˜50--100 Myr, irons from each core would have

  20. Organic Compounds in Carbonaceous Meteorites

    NASA Technical Reports Server (NTRS)

    Cooper, Grorge

    2001-01-01

    Carbonaceous meteorites are relatively enriched in soluble organic compounds. To date, these compounds provide the only record available to study a range of organic chemical processes in the early Solar System chemistry. The Murchison meteorite is the best-characterized carbonaceous meteorite with respect to organic chemistry. The study of its organic compounds has related principally to aqueous meteorite parent body chemistry and compounds of potential importance for the origin of life. Among the classes of organic compounds found in Murchison are amino acids, amides, carboxylic acids, hydroxy acids, sulfonic acids, phosphonic acids, purines and pyrimidines (Table 1). Compounds such as these were quite likely delivered to the early Earth in asteroids and comets. Until now, polyhydroxylated compounds (polyols), including sugars (polyhydroxy aldehydes or ketones), sugar alcohols, sugar acids, etc., had not been identified in Murchison. Ribose and deoxyribose, five-carbon sugars, are central to the role of contemporary nucleic acids, DNA and RNA. Glycerol, a three-carbon sugar alcohol, is a constituent of all known biological membranes. Due to the relative lability of sugars, some researchers have questioned the lifetime of sugars under the presumed conditions on the early Earth and postulated other (more stable) compounds as constituents of the first replicating molecules. The identification of potential sources and/or formation mechanisms of pre-biotic polyols would add to the understanding of what organic compounds were available, and for what length of time, on the ancient Earth.

  1. Extraterrestrial Organic Compounds in Meteorites

    NASA Technical Reports Server (NTRS)

    Botta, Oliver; Bada, Jeffrey L.; Meyer, Michael (Technical Monitor)

    2003-01-01

    Many organic compounds or their precursors found in meteorites originated in the interstellar or circumstellar medium and were later incorporated into planetesimals during the formation of the solar system. There they either survived intact or underwent further processing to synthesize secondary products on the meteorite parent body. The most distinct feature of CI and CM carbonaceous chondrites, two types of stony meteorites, is their high carbon content (up to 3% of weight), either in the form of carbonates or of organic compounds. The bulk of the organic carbon consists of an insoluble macromolecular material with a complex structure. Also present is a soluble organic fraction, which has been analyzed by several separation and analytical procedures. Low detection limits can be achieved by derivatization of the organic molecules with reagents that allow for analysis by gas chromatography/mass spectroscopy and high performance liquid chromatography. The CM meteorite Murchison has been found to contain more than 70 extraterrestrial amino acids and several other classes of compounds including carboxylic acids, hydroxy carboxylic acids, sulphonic and phosphonic acids, aliphatic, aromatic and polar hydrocarbons, fullerenes, heterocycles as well as carbonyl compounds, alcohols, amines and amides. The organic matter was found to be enriched in deuterium, and distinct organic compounds show isotopic enrichments of carbon and nitrogen relative to terrestrial matter.

  2. Fireball data analysis: bridging the gap between small solar system bodies and meteorite studies

    NASA Astrophysics Data System (ADS)

    Gritsevich, Maria; Moreno-Ibáñez, Manuel; Kuznetsova, Daria; Bouquet, Alexis; Trigo-Rodríguez, Josep; Peltoniemi, Jouni; Koschny, Detlef

    2015-08-01

    One of the important steps in identification of meteorite-producing fireballs and prediction of impact threat to Earth raised by potentially hazardous asteroids is the understanding and modeling of processes accompanying the object’s entry into the terrestrial atmosphere (Gritsevich et al., 2012). Such knowledge enables characterization, simulation and classification of possible impact consequences with further reommendation for potential meteorite searches. Using dimensionless expressions, which involve the pre-atmospheric meteoroid parameters, we have built physically based parametrisation to describe changes in mass, height, velocity and luminosity of the object along its atmospheric path (Gritsevich and Koschny, 2011; Bouquet et al., 2014). The developed model is suitable to estimate a number of crucial unknown values including shape change coefficient, ablation rate, and surviving meteorite mass. It is also applicable to predict the terminal height of the luminous flight and therefore, duration of the fireball (Moreno-Ibáñez et al., 2015). Besides the model description, we demonstrate its application using the wide range of observational data from meteorite-producing fireballs appearing annually (such as Košice) to larger scale impacts (such as Chelyabinsk, Sikhote-Alin and Tunguska).REFERENCESBouquet A., Baratoux D., Vaubaillon J., Gritsevich M.I., Mimoun D., Mousis O., Bouley S. (2014): Planetary and Space Science, 103, 238-249, http://dx.doi.org/10.1016/j.pss.2014.09.001Gritsevich M., Koschny D. (2011): Icarus, 212(2), 877-884, http://dx.doi.org/10.1016/j.icarus.2011.01.033Gritsevich M.I., Stulov V.P., Turchak L.I. (2012): Cosmic Research, 50(1), 56-64, http://dx.doi.org/10.1134/S0010952512010017Moreno-Ibáñez M., Gritsevich M., Trigo-Rodríguez J.M. (2015): Icarus, 250, 544-552, http://dx.doi.org/10.1016/j.icarus.2014.12.027

  3. 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

  4. Communication with Parents and Body Satisfaction in College Students

    ERIC Educational Resources Information Center

    Taniguchi, Emiko; Aune, R. Kelly

    2013-01-01

    Objective: This study examined how communication with parents is related to college students' body satisfaction. Participants and Methods: Participants ("N" = 134; 58 males and 76 females) completed a survey in March 2011 assessing body satisfaction and perceptions of communication with mothers and fathers. Results: Daughters'…

  5. Ar-39-Ar-40 Evidence for Early Impact Events on the LL Parent Body

    NASA Technical Reports Server (NTRS)

    Dixon, E. T.; Bogard, D. D.; Garrison, D. H.; Rubin, A. E.

    2006-01-01

    We determined Ar-39-Ar-40 ages of eight LL chondrites, and one igneous inclusion from an LL chondrite, with the object of understanding the thermal history of the LL-chondrite parent body. The meteorites in this study have a range of petrographic types from LL3.3 to LL6, and shock stages from S1 to S4. These meteorites reveal a range of K-Ar ages from 23.66 to 24.50 Ga, and peak ages from 23.74 to 24.55 Ga. Significantly, three of the eight chondrites (LL4, 5, 6) have K-Ar ages of -4.27 Ga. One of these (MIL99301) preserves an Ar-39-Ar-40 age of 4.23 +/- 0.03 Ga from low-temperature extractions, and an older age of 4.52 +/- 0.08 Ga from the highest temperature extractions. In addition, an igneous-textured impact melt DOM85505,22 has a peak Ar-39-Ar-40 age of >= 4.27 Ga. We interpret these results as evidence for impact events that occurred at about 4.27 Ga on the LL parent body that produced local impact melts, reset the Ar-39-Ar-40 ages of some meteorites, and exhumed (or interred) others, resulting in a range of cooling ages. The somewhat younger peak age of 3.74 Ga from GR095658 (LL3.3) suggests an additional impact event close to timing of impact-reset ages of some other ordinary chondrites between 3.6-3.8 Ga. The results from MIL99301 suggest that some apparently unshocked (Sl) chondrites may have substantially reset Ar-39-Ar-40 ages. A previous petrographic investigation of MIL99301 suggested that reheating to temperatures less than or equal to type 4 petrographic conditions (600C) caused fractures in olivine to anneal, resulting in a low apparent shock stage of S1 (unshocked). The Ar-39-Ar-40 age spectrum of MIL99301 is consistent with this interpretation. Older ages from high-T extractions may date an earlier impact event at 4.52 +/- 0.08 Ga, whereas younger ages from lower-T extractions date a later impact event at 4.23 Ar-39-Ar-40 0.03 Ga that may have caused annealing of feldspar and olivine

  6. 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

  7. The effects of parent body processes on amino acids in carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    To investigate the effect of parent body processes on the abundance, distribution, and enantiomeric composition of amino acids in carbonaceous chondrites, the water extracts from nine different powdered CI, CM, and CR carbonaceous chondrites were analyzed for amino acids by ultra performance liquid chromatography-fluorescence detection and time-of-flight mass spectrometry (UPLC-FD/ToF-MS). Four aqueously altered type 1 carbonaceous chondrites including Orgueil (CI1), Meteorite Hills (MET) 01070 (CM1), Scott Glacier (SCO) 06043 (CM1), and Grosvenor Mountains (GRO) 95577 (CR1) were analyzed using this technique for the first time. Analyses of these meteorites revealed low levels of two- to five-carbon acyclic amino alkanoic acids with concentrations ranging from approximately 1 to 2,700 parts-per-billion (ppb). The type 1 carbonaceous chondrites have a distinct distribution of the five-carbon (C5) amino acids with much higher relative abundances of the γ- and δ-amino acids compared to the type 2 and type 3 carbonaceous chondrites, which are dominated by α-amino acids. Much higher amino acid abundances were found in the CM2 chondrites Murchison, Lonewolf Nunataks (LON) 94102, and Lewis Cliffs (LEW) 90500, the CR2 Elephant Moraine (EET) 92042, and the CR3 Queen Alexandra Range (QUE) 99177. For example, α-aminoisobutyric acid (α-AIB) and isovaline were approximately 100 to 1000 times more abundant in the type 2 and 3 chondrites compared to the more aqueously altered type 1 chondrites. Most of the chiral amino acids identified in these meteorites were racemic, indicating an extraterrestrial abiotic origin. However, nonracemic isovaline was observed in the aqueously altered carbonaceous chondrites Murchison, Orgueil, SCO 06043, and GRO 95577 with L-isovaline excesses ranging from approximately 11 to 19%, whereas the most pristine, unaltered carbonaceous chondrites analyzed in this study had no detectable L-isovaline excesses. These results are consistent with the

  8. Aerodynamic Analysis of Tektites and Their Parent Bodies

    NASA Technical Reports Server (NTRS)

    Adams, E. W.; Huffaker, R. M.

    1962-01-01

    Experiment and analysis indicate that the button-type australites were derived from glassy spheres which entered or re-entered the atmosphere as cold solid bodies; in case of average-size specimens, the entry direction was nearly horizontal and the entry speed between 6.5 and 11.2 km/sec. Terrestrial origin of such spheres is impossible because of extremely high deceleration rates at low altitudes. The limited extension of the strewn fields rules out extraterrestrial origin of clusters of such spheres because of stability considerations for clusters in space. However, tektites may have been released as liquid droplets from glassy parent bodies ablating in the atmosphere of the earth. The australites then have skipped together with the parent body in order to re-enter as cold spheres. Terrestrial origin of a parent body would require an extremely violent natural event. Ablation analysis shows that fusion of opaque siliceous stone into glass by aerodynamic heating is impossible.

  9. Carbonaceous meteorites contain a wide range of extraterrestrial nucleobases.

    PubMed

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

    2011-08-23

    All terrestrial organisms depend on nucleic acids (RNA and DNA), which use pyrimidine and purine nucleobases to encode genetic information. Carbon-rich meteorites may have been important sources of organic compounds required for the emergence of life on the early Earth; however, the origin and formation of nucleobases in meteorites has been debated for over 50 y. So far, the few nucleobases reported in meteorites are biologically common and lacked the structural diversity typical of other indigenous meteoritic organics. Here, we investigated the abundance and distribution of nucleobases and nucleobase analogs in formic acid extracts of 12 different meteorites by liquid chromatography-mass spectrometry. The Murchison and Lonewolf Nunataks 94102 meteorites contained a diverse suite of nucleobases, which included three unusual and terrestrially rare nucleobase analogs: purine, 2,6-diaminopurine, and 6,8-diaminopurine. In a parallel experiment, we found an identical suite of nucleobases and nucleobase analogs generated in reactions of ammonium cyanide. Additionally, these nucleobase analogs were not detected above our parts-per-billion detection limits in any of the procedural blanks, control samples, a terrestrial soil sample, and an Antarctic ice sample. Our results demonstrate that the purines detected in meteorites are consistent with products of ammonium cyanide chemistry, which provides a plausible mechanism for their synthesis in the asteroid parent bodies, and strongly supports an extraterrestrial origin. The discovery of new nucleobase analogs in meteorites also expands the prebiotic molecular inventory available for constructing the first genetic molecules.

  10. Carbonaceous Meteorites Contain a Wide Range of Extraterrestrial Nucleobases

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    All terrestrial organisms depend on nucleic acids (RNA and DNA), which use pyrimidine and purine nucleobases to encode genetic information. Carbon-rich meteorites may have been important sources of organic compounds required for the emergence of life on the early Earth; however, the origin and formation of nuc1eobases in meteorites has been debated for over 50 y. So far, the few nuc1eobases reported in meteorites are biologically common and lacked the structural diversity typical of other indigenous meteoritic organics. Here, we investigated the abundance and distribution of nucleobases and nucleobase analogs in formic acid extracts of 12 different meteorites by liquid chromatography-mass spectrometry. The Murchison and Lonewolf Nunataks 94102 meteorites contained a diverse suite of nucleobases, which included three unusual and terrestrially rare nucleobase analogs; purine, 2,6-diminopurine, and 6,8-diaminopurine. In a parallel experiment, we found an identical suite of nucleobases and nucleobase analogs generated in reactions of ammonium cyanide. Additionally, these nucleobase analoge were not detected above our parts-per-billion detection limits in any of the procedural blanks, control samples, a terrestrial soil sample, and an Antarctic ice sample. Our results demonstrate that the purines detected in meteorites are consistent with products of ammonium cyanide chemistry, which provides a plausible mechanism for their synthesis in the asteroid parent bodies, and strongly supports an extraterrestrial origin. The discovery of new nucleobase analogs in meteorites also expands the prebiotic molecular inventory available for constructing the first genetic molecules.

  11. Chondrule Magnetizations in the Allende CV Chondrite and Implications for the Dynamo of the CV Parent Body

    NASA Astrophysics Data System (ADS)

    Weiss, B. P.; Fu, R. R.

    2012-12-01

    Many early-accreting planetesimals larger than several tens of km in diameter underwent extensive interior melting and differentiation. Advection in the molten metallic cores of these planetesimals may have generated magnetic dynamos. Remanent magnetization preserved in meteorites can reveal the past presence of core dynamo fields and therefore a metallic core on their parent bodies. Furthermore, the meteoritic magnetic record can constrain the duration of the dynamo, providing insight into the thermal evolution of the parent planetesimal. Carporzen et al. (2011) argued that bulk samples of the Allende CV carbonaceous chondrite carry a unidirectional partial thermoremanent magnetization (pTRM) blocked up to ~290C. They interpreted this magnetization as recording a magnetic core dynamo on the CV parent body. However, the previous study provided no constraints on the duration of the dynamo and did not characterize the magnetic recording in each component of the Allende meteorite. We conducted paleomagnetic experiments on 23 mutually oriented individual Allende chondrules and matrix samples. We also studied mutually oriented subsamples of 9 of these chondrules. We found that Allende chondrules can be divided into two distinct classes based on their natural remanent magnetization (NRM). Class A chondrules carry a strong low temperature overprint parallel to that of bulk Allende and matrix material that also unblocks at ~290C. Class B chondrules do not carry this low temperature overprint and exhibit randomly oriented NRMs. Electron microprobe analysis and thermal demagnetization of saturation remanence showed that magnetic phases in both Class A and Class B chondrules are likely products of parent body metasomatism. We infer that the random magnetization of Class B chondrules as well as the magnetization blocked above 290C in Class A chondrules and matrix material is a chemical remanent magnetization that resulted in randomly oriented remanence at the sub

  12. Workshop on Oxygen in Asteroids and Meteorites

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Contents include the following: Constraints on the detection of solar nebula's oxidation state through asteroid observation. Oxidation/Reduction Processes in Primitive Achondrites. Low-Temperature Chemical Processing on Asteroids. On the Formation Location of Asteroids and Meteorites. The Spectral Properties of Angritic Basalts. Correlation Between Chemical and Oxygen Isotopic Compositions in Chondrites. Effect of In-Situ Aqueous Alteration on Thermal Model Heat Budgets. Oxidation-Reduction in Meteorites: The Case of High-Ni Irons. Ureilite Atmospherics: Coming up for Air on a Parent Body. High Temperature Effects Including Oxygen Fugacity, in Pre-Planetary and Planetary Meteorites and Asteroids. Oxygen Isotopic Variation of Asteroidal Materials. High-Temperature Chemical Processing on Asteroids: An Oxygen Isotope Perspective. Oxygen Isotopes and Origin of Opaque Assemblages from the Ningqiang Carbonaceous Chondrite. Water Distribution in the Asteroid Belt. Comparative Planetary Mineralogy: V Systematics in Planetary Pyroxenes and fo 2 Estimates for Basalts from Vesta.

  13. Time-Resolved Records of Magnetic Activity on the Pallasite Parent Body and Psyche

    NASA Astrophysics Data System (ADS)

    Bryson, J. F. J.; Nichols, C. I. O.; Herrero-Albillos, J.; Kronast, F.; Kasama, T.; Alimadadi, H.; van der Laan, G.; Nimmo, F.; Harrison, R. J.

    2014-12-01

    Although many small bodies apparently generated dynamo fields in the early solar system, the nature and temporal evolution of these fields has remained enigmatic. Time-resolved records of the Earth's planetary field have been essential in understanding the dynamic history of our planet, and equivalent information from asteroids could provide a unique insight into the development of the solar system. Here we present time-resolved records of magnetic activity on the main-group pallasite parent body and (16) Psyche, obtained using newly-developed nanomagnetic imaging techniques. For the pallasite parent body, the inferred field direction remained relatively constant and the intensity was initially stable at ~100 μT before it decreased in two discrete steps down to 0 μT. We interpret this behaviour as due to vigorous dynamo activity driven by compositional convection in the core, ultimately transitioning from a dipolar to multipolar field as the inner core grew from the bottom-up. For Psyche (measured from IVA iron meteorites), the inferred field direction reversed, while the intensity remained stable at >50 μT. Psyche cooled rapidly as an unmantled core, although the resulting thermal convection alone cannot explain these observations. Instead, this behaviour required top-down core solidification, and is attributed either to compositional convection (if the core also solidified from the bottom-up) or convection generated directly by top-down solidification (e.g. Fe-snow). The mechanism governing convection in small body cores is an open question (due partly to uncertainties in the direction of core solidification), and these observations suggest that unconventional (i.e. not thermal) mechanisms acted in the early solar system. These mechanisms are very efficient at generating convection, implying a long-lasting and widespread epoch of dynamo activity among small bodies in the early solar system.

  14. Thermal and impact histories of reheated group IVA, IVB, and ungrouped iron meteorites and their parent asteroids

    NASA Astrophysics Data System (ADS)

    Yang, J.; Goldstein, J. I.; Scott, E. R. D.; Michael, J. R.; Kotula, P. G.; Pham, T.; McCoy, T. J.

    2011-09-01

    Abstract- The microstructures of six reheated iron meteorites—two IVA irons, Maria Elena (1935), Fuzzy Creek; one IVB iron, Ternera; and three ungrouped irons, Hammond, Babb’s Mill (Blake’s Iron), and Babb’s Mill (Troost’s Iron)—were characterized using scanning and transmission electron microscopy, electron-probe microanalysis, and electron backscatter diffraction techniques to determine their thermal and shock history and that of their parent asteroids. Maria Elena and Hammond were heated below approximately 700-750 °C, so that kamacite was recrystallized and taenite was exsolved in kamacite and was spheroidized in plessite. Both meteorites retained a record of the original Widmanstätten pattern. The other four, which show no trace of their original microstructure, were heated above 600-700 °C and recrystallized to form 10-20 μm wide homogeneous taenite grains. On cooling, kamacite formed on taenite grain boundaries with their close-packed planes aligned. Formation of homogeneous 20 μm wide taenite grains with diverse orientations would have required as long as approximately 800 yr at 600 °C or approximately 1 h at 1300 °C. All six irons contain approximately 5-10 μm wide taenite grains with internal microprecipitates of kamacite and nanometer-scale M-shaped Ni profiles that reach approximately 40% Ni indicating cooling over 100-10,000 yr. Un-decomposed high-Ni martensite (α2) in taenite—the first occurrence in irons—appears to be a characteristic of strongly reheated irons. From our studies and published work, we identified four progressive stages of shock and reheating in IVA irons using these criteria: cloudy taenite, M-shaped Ni profiles in taenite, Neumann twin lamellae, martensite, shock-hatched kamacite, recrystallization, microprecipitates of taenite, and shock-melted troilite. Maria Elena and Fuzzy Creek represent stages 3 and 4, respectively. Although not all reheated irons contain evidence for shock, it was probably the main

  15. Near-infrared spectroscopy of 3:1 Kirkwood Gap asteroids II: Probable and plausible parent bodies; primitive and differentiated

    NASA Astrophysics Data System (ADS)

    Fieber-Beyer, Sherry K.; Gaffey, Michael J.

    2014-02-01

    The 3:1 Kirkwood Gap asteroids are a mineralogically diverse set of asteroids located in a region that delivers meteoroids into Earth-crossing orbits. Mineralogical characterizations of asteroids in/near the 3:1 Kirkwood Gap can be used as a tool to “map” conditions and processes in the early Solar System. The chronological studies of the meteorite types provide a “clock” for the relative timing of those events and processes. By identifying the source asteroids of particular meteorite types, the “map” and “clock” can be combined to provide a much more sophisticated understanding of the history and evolution of the late solar nebula and the early Solar System. A mineralogical assessment of twelve 3:1 Kirkwood Gap asteroids has been carried out using near-infrared spectral data obtained from 2010 to 2011 combined with visible spectral data (when available) to cover the spectral interval of 0.4-2.5 μm. Eight of these asteroids have surfaces with basaltic-type silicate assemblages, indicating at least partial melting within their parent bodies. Although HED-like mineralogies are present these objects exhibit subdued features indicating the presence of an additional phase (e.g., NiFe metal) or process (e.g., space weathering). Four of these asteroids appear to be ordinary chondrite assemblages. Three of these are plausibly linked to the probable H-chondrite parent body, (6) Hebe.

  16. Rhenium-osmium-isotope constraints on the age of iron meteorites

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    Rhenium and osmium concentrations and the osmium isotopic compositions of iron meteorites were determined by negative thermal ionization mass spectrometry. Data for the IIA iron meteorites define an isochron with an uncertainty of approximately +/-31 million years for meteorites about 4500 million years old. Although an absolute rhenium-osmium closure age for this iron group cannot be as precisely constrained because of uncertainty in the decay constant of Re-187, an age of 4460 million years ago is the minimum permitted by combined uncertainties. These age constraints imply that the parent body of the IIAB magmatic irons melted and subsequently cooled within 100 million years after the formation of the oldest portions of chondrites. Other iron meteorites plot above the IIA isochron, indicating that the planetary bodies represented by these iron groups may have cooled significantly later than the parent body of the IIA irons.

  17. Rhenium-osmium isotope constraints on the age of iron meteorites

    USGS Publications Warehouse

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

    1992-01-01

    Rhenium and osmium concentrations and the osmium isotopic compositions of iron meteorites were determined by negative thermal ionization mass spectrometry. Data for the IIA iron meteorites define an isochron with an uncertainty of approximately ??31 million years for meteorites ???4500 million years old. Although an absolute rhenium-osmium closure age for this iron group cannot be as precisely constrained because of uncertainty in the decay constant of 187Re, an age of 4460 million years ago is the minimum permitted by combined uncertainties. These age constraints imply that the parent body of the IIAB magmatic irons melted and subsequently cooled within 100 million years after the formation of the oldest portions of chondrites. Other iron meteorites plot above the IIA isochron, indicating that the planetary bodies represented by these iron groups may have cooled significantly later than the parent body of the IIA irons.

  18. Water and the thermal evolution of carbonaceous chondrite parent bodies

    NASA Technical Reports Server (NTRS)

    Grimm, Robert E.; Mcsween, Harry Y., Jr.

    1989-01-01

    Two hypotheses are proposed for the aqueous alteration of carbonaceous chondrites within their parent bodies, in which respectively the alteration occurs (1) throughout the parent body interior, or (2) in a postaccretional surface regolith; both models assume an initially homogeneous mixture of ice and rock that is heated through the decay of Al-26. Water is seen to exert a powerful influence on chondrite evolution through its role of thermal buffer, permitting substitution of a low temperature aqueous alteration for high temperature recrystallization. It is quantitatively demonstrated that liquid water may be introduced by either hydrothermal circulation, vapor diffusion from below, or venting due to fracture.

  19. Embodied grief: bereaved parents' narratives of their suffering body.

    PubMed

    Gudmundsdottir, Maria

    2009-01-01

    Experiences and symptoms emanating from the bereaved person's body are commonly considered to be psychosomatic reactions to loss. The lingering of such experiences is thought to reflect a maladaptive coping style that needs to be addressed to access the psychological pain underlying the symptoms. In this interpretive, phenomenological study of 15 family members in seven families who lost a child to sudden, unexpected death, stories of embodied grief are explored to further understand the grieving body. The findings of this study illuminate the many ways parents experience their grieving body and they underscore the importance of witnessing and acknowledging stories of the body in clinical work with bereaved parents who are learning to live in a world without their beloved child. PMID:19791520

  20. The Production of Amino Acids in Interstellar Ices: Implications for Meteoritic Organics

    NASA Technical Reports Server (NTRS)

    Sandford, A.; Bernstein, M. P.; Dworkin, J. P.; Cooper, G. W.; Allamandola, L. J.; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    Indigenous amino acids have been detected in a number of meteorites, over 70 in the Murchison meteorite alone. It has been generally accepted that the amino acids in meteorites formed in liquid water on an asteroid or comet parent-body. However, the water in the Murchison meteorite, for example, was depleted of deuterium, making the distribution of deuterium in organic acids in Murchison difficult to explain. Similarly, occasional but consistent meteoritic biases for non-terrestrial L amino acids cannot be reasonably rationalized by liquid water parent-body reactions. We will present the results of a laboratory demonstration showing that the amino acids glycine, alanine, and serine should result from the UV (ultraviolet) photolysis of interstellar ice grains. This suggests that some meteoritic amino acids may be the result of interstellar ice photochemistry, rather than having formed by reactions in liquid water. We will describe some of the potential implications of these findings for the organic materials found in primitive meteorites, in particular how interstellar ice synthesis might more easily accommodate the presence and distribution of deuterium, and the meteoritic bias for L amino acids.

  1. Clay minerals in primitive meteorites and interplanetary dust 1

    NASA Technical Reports Server (NTRS)

    Zolensky, M. E.; Keller, L. P.

    1991-01-01

    Many meteorites and interplanetary dust particles (IDPs) with primitive compositions contain significant amounts of phyllosilicate minerals, which are generally interpreted as evidence of protoplanetary aqueous alteration at an early period of the solar system. These meteorites are chondrites (near solar composition) of the carbonaceous and ordinary varieties. The former are subdivided (according to bulk composition and petrology) into CI, CM, CV, CO, CR, and ungrouped classes. IDPs are extraterrestrial particulates, collected in stratosphere, which have chemical compositions indicative of a primitive origin; they are typically distinct from the primitive meteorites. Characterization of phyllosilicates in these materials is a high priority because of the important physico-chemical information they hold. The most common phyllosilicates present in chondritic extraterrestrial materials are serpentine-group minerals, smectites, and micas. We discuss these phyllosilicates and describe the interpretation of their occurrence in meteorites and IDPs and what this indicates about history of their parent bodies, which are probably the hydrous asteroids.

  2. Bidirectional reflectance measurements of meteorites acquired by FGI's field goniospectrometer

    NASA Astrophysics Data System (ADS)

    Gritsevich, Maria; Hakala, Teemu; Peltoniemi, Jouni; Paton, Mark; Stenman, Jarkko; Luttinen, Arto

    2013-01-01

    Meteorite studies represent a low-cost opportunity for probing the cosmic matter that reaches the Earth's surface, and for revealing the origin of our Solar System. In addition, they complement results of sample-return missions that bring back pristine samples of this material. The main difficulty, however, with interpreting meteorite records is that, apart from a few exceptional cases, we do not know their exact origin, i.e., the parent body a particular sample is coming from. In the present study, we provide results of multi-angular bidirectional reflectance measurements of relatively big meteorite samples, from the Finnish Museum of Natural History, using the field goniospectrometer Figifigo. We discuss possible matches between our measured reflectance spectra of meteorites with the reflectance spectra of asteroids. We discuss the features in the spectra and their relationship to the physical properties of the sample/asteroid.

  3. About 129Xe ∗ in meteoritic nanodiamonds

    NASA Astrophysics Data System (ADS)

    Fisenko, A. V.; Semjonova, L. F.

    2008-08-01

    The analysis of excess 129Xe in meteoritic nanodiamonds and the kinetics of its release during stepwise pyrolysis allow to suggest that (1) in the solar nebula 129I atoms were adsorbed onto nanodiamond grains and (or) chemisorbed by forming covalent bonds with carbon atoms. Most 129I atoms existed in a surface connected state, but a minor amount of them was in nanopores of the grains. At radioactive decay of 129I the formed 129Xe ( 129Xe ∗) was trapped by diamond grains due to nuclear recoil. (2) During thermal metamorphism or aqueous alteration, the surface-sited 129I atoms were basically lost. On the basis of these assumptions and calculated concentrations of 129Xe ∗ in meteoritic nanodiamonds it is shown that the minimum closing time of the I-Xe system for meteorites of different chemical classes and low petrologic types may be about one million years relative to the minimally thermally metamorphized CO3 meteorite ALHA 77307. With increasing metamorphic grade the closing time of the I-Xe system increases and can range up to several ten millions years. This tendency is in agreement with an onion-shell model of structure and cooling history of meteorite parent bodies where the temperature increases in the direction from surface to center of the asteroids.

  4. Unusual Dark Clasts in the Vigarano CV3 Chondrite: Record of Parent Body Process

    NASA Astrophysics Data System (ADS)

    Kojima, T.; Tomeoka, K.; Takeda, H.

    1993-07-01

    A variety of dark lithic clasts have been reported from CV3 chondrites and are commonly called "dark inclusions" (DIs). The DIs widely range in texture from chondritic with chondrules and Ca-Al-rich inclusions (CAIs) embedded in a matrix (similar to host meteorites), to fine-grained aggregates of Fe-rich olivine free of coarse-grained components [1,2]. The DIs have been interpreted to represent (1) primary aggregates of materials in the solar nebula [3-5] and (2) materials that were affected by thermal metamorphism on their parent bodies [6]. We present the results of petrographic and scanning electron microscope (SEM) studies of two unusual clasts found in the Vigarano CV3 chondrite. The two unusual clasts, which we will call CL1 and CL2, are approximately 1.2 x 1.0 mm^2 (CLl) and 0.8 x 0.6 mm^2 (CL2) and occur within one of the large clasts (2.8 x 1.0 mm^2). CL1 and CL2 have very similar mineralogies and textures; they contain irregular to oval-shaped inclusions consisting mostly of fine grains of Fe-rich olivine embedded in the matrix of the clasts, and are free of distinct chondrules, CAIs, and coarse mineral fragments. Thus, they resemble the fine-grained variety of DIs. Under the optical microscope, most inclusions resemble chondrules or chondrule fragments in shape and size. However, they are brownish-translucent in transmitted light and are clearly distinct from chondrules in the Vigarano host. The inclusions are characteristically flattened in direction, exhibiting apparent foliation. Our SEM observations reveal the following unusual characteristics: (1) the inclusions are not mere random aggregates of olivine grains but have peculiar internal textures, i.e., assemblies of round or oval-shaped outlines, which are suggestive of pseudomorphs after porphyritic or granular olivine chondrules; (2) one of the thick inclusion rims contains a network of vein-like strings of elongated olivine grains, (3) an Fe-Ni metal aggregate in CL1 has an Fe-, Ni-, S-rich halo

  5. Child's Weight Status and Parent's Response to a School-Based Body Mass Index Screening and Parent Notification Program

    ERIC Educational Resources Information Center

    Lee, Jiwoo; Kubik, Martha Y.

    2015-01-01

    This study examined the response of parents of elementary school-aged children to a school-based body mass index (BMI) screening and parent notification program conducted in one Minnesota school district in 2010-2011 and whether parent's response was moderated by child's weight status. Randomly selected parents (N = 122) of second- and…

  6. Characteristics and formation of amino acids and hydroxy acids of the Murchison meteorite

    NASA Technical Reports Server (NTRS)

    Cronin, J. R.; Cooper, G. W.; Pizzarello, S.

    1995-01-01

    Eight characteristics of the unique suite of amino acids and hydroxy acids found in the Murchison meteorite can be recognized on the basis of detailed molecular and isotopic analyses. The marked structural correspondence between the alpha-amino acids and alpha-hydroxy acids and the high deuterium/hydrogen ratio argue persuasively for their formation by aqueous phase Strecker reactions in the meteorite parent body from presolar, i.e., interstellar, aldehydes, ketones, ammonia, and hydrogen cyanide. The characteristics of the meteoritic suite of amino acids and hydroxy acids are briefly enumerated and discussed with regard to their consonance with this interstellar-parent body formation hypothesis. The hypothesis has interesting implications for the organic composition of both the primitive parent body and the presolar nebula.

  7. Heterogeneous Distributions of Amino Acids Provide Evidence of Multiple Sources Within the Almahata Sitta Parent Body, Asteroid 2008 TC(sub 3)

    NASA Technical Reports Server (NTRS)

    Burton, Aaron S.; Glavin, Daniel P.; Callahan, Michael P.; Dworkin, Jason P.; Jenniskens, Peter; Shaddad, Muawia H.

    2011-01-01

    Two new fragments of the Almahata Sitta meteorite and a sample of sand from the related strewn field in the Nubian Desert, Sudan, were analyzed for two to six carbon aliphatic primary amino acids by ultrahigh performance liquid chromatography with UV-fluorescence detection and time-of-flight mass spectrometry (LC-FT/ToF-MS). The distribution of amino acids in fragment #25, an H5 ordinary chondrite, and fragment #27, a polymict ureilite, were compared with results from the previously analyzed fragment #4, also a polymict ureilite. All three meteorite fragments contain 180-270 parts-per-billion (ppb) of amino acids, roughly 1000-fold lower than the total amino acid abundance of the Murchison carbonaceous chondrite. All of the Almahata Sitta fragments analyzed have amino acid distributions that differ from the Nubian Desert sand, which primarily contains L-alpha-amino acids. In addition, the meteorites contain several amino acids that were not detected in the sand, indicating that many of the amino acids are extraterrestrial in origin. Despite their petrological differences, meteorite fragments #25 and #27 contain similar amino acid compositions; however, the distribution of amino acids in fragment #27 was distinct from those in fragment #4, even though both arc polymict ureilites from the same parent body. Unlike in CM2 and CR2/3 meteorites, there are low relative abundances of alpha-amino acids in the Almahata Sitta meteorite fragments, which suggest that Strecker-type chemistry was not a significant amino acid formation mechanism. Given the high temperatures that asteroid 2008 TC3 appears to have experienced and lack of evidence for aqueous alteration on the asteroid, it is possible that the extraterrestrial amino acids detected in Almahata Sitta were formed by Fischer-Tropsch/Haber-Bosch type gas-grain reactions at elevated temperatures.

  8. The 2014 KCG Meteor Outburst: Clues to a Parent Body

    NASA Technical Reports Server (NTRS)

    Moorhead, Althea V.; Brown, Peter G.; Spurny, Pavel; Cooke, William J.

    2015-01-01

    The Kappa Cygnid (KCG) meteor shower exhibited unusually high activity in 2014, producing ten times the typical number of meteors. The shower was detected in both radar and optical systems and meteoroids associated with the outburst spanned at least five decades in mass. In total, the Canadian Meteor Orbit Radar, European Network, and NASA All Sky and Southern Ontario Meteor Network produced thousands of KCG meteor trajectories. Using these data, we have undertaken a new and improved characterization of the dynamics of this little-studied, variable meteor shower. The Cygnids have a di use radiant and a significant spread in orbital characteristics, with multiple resonances appearing to play a role in the shower dynamics. We conducted a new search for parent bodies and found that several known asteroids are orbitally similar to the KCGs. N-body simulations show that the two best parent body candidates readily transfer meteoroids to the Earth in recent centuries, but neither produces an exact match to the KCG radiant, velocity, and solar longitude. We nevertheless identify asteroid 2001 MG1 as a promising parent body candidate.

  9. Meteorite Fractures and Scaling for Atmospheric Entry

    NASA Astrophysics Data System (ADS)

    Bryson, Kathryn L.; Ostrowski, Daniel R.

    2016-10-01

    We are attempting to understand the behavior of asteroids entering the atmosphere in order to help quantify the impact hazard. The strength of meteorites plays a critical role in determining the outcome of their impact events. Our objective is to scale fracture parameters in meteorites to their parent body.In this study over a thousand meteorite fragments in the Natural History Museums of Vienna and London (mostly hand-sized, some 40 or 50 cm across) were examined and fracture patterns in selected fragments were imaged. We identified six kinds of fracturing behavior. The density and length of the observed fractures were measured in hand specimens and thin sections. We assume that fracturing follows the Weibull distribution, where fractures are assumed to be randomly distributed through the target and the likelihood of encountering a fracture increases with distance. The images collected of the six fracture behaviors provide a two-dimensional view of the fractures. A relationship exists between the distributions of measured trace length and actual fracture size, where the slope of a log-log plot of trace length vs fracture density is proportional to α, the shape parameter. The value for α is unclear and a large range in α has been determined from light curve data. α can be used to scale strengths from the meteorite to the larger parent body.The majority of the meteorite fractures imaged displayed no particular sensitivity to meteorite texture. A value of α of 0.185 has been determined for a chondrite with a fracture pattern that shows no sensitivity to meteorite texture and has no point of origin. This study will continue to examine additional meteorites with similar fracture patterns along with the other 5 patterns to see if there is a correlation between fracture pattern and α. This may explain the variations in α determined from fireball data. Values of α will be used in models created by the Asteroid Threat Assessment Project to try to determine the

  10. Nature's starships. I. Observed abundances and relative frequencies of amino acids in meteorites

    SciTech Connect

    Cobb, Alyssa K.; Pudritz, Ralph E. E-mail: pudritz@physics.mcmaster.ca

    2014-03-10

    The class of meteorites called carbonaceous chondrites are examples of material from the solar system which have been relatively unchanged from the time of their initial formation. These meteorites have been classified according to the temperatures and physical conditions of their parent planetesimals. We collate available data on amino acid abundance in these meteorites and plot the concentrations of different amino acids for each meteorite within various meteorite subclasses. We plot average concentrations for various amino acids across meteorites separated by subclass and petrologic type. We see a predominance in the abundance and variety of amino acids in CM2 and CR2 meteorites. The range in temperature corresponding to these subclasses indicates high degrees of aqueous alteration, suggesting aqueous synthesis of amino acids. Within the CM2 and CR2 subclasses, we identify trends in relative frequencies of amino acids to investigate how common amino acids are as a function of their chemical complexity. These two trends (total abundance and relative frequencies) can be used to constrain formation parameters of amino acids within planetesimals. Our organization of the data supports an onion shell model for the temperature structure of planetesimals. The least altered meteorites (type 3) and their amino acids originated near cooler surface regions. The most active amino acid synthesis likely took place at intermediate depths (type 2). The most altered materials (type 1) originated furthest toward parent body cores. This region is likely too hot to either favor amino acid synthesis or for amino acids to be retained after synthesis.

  11. The Kelly chondrite - A parent body surface metabreccia

    NASA Technical Reports Server (NTRS)

    Bunch, T. E.; Stoeffler, D.

    1974-01-01

    A study of the Kelly chondrite classes it as a monomict breccia rather than a polymict breccia as it was originally described. Microprobe analyses of differently textured clasts are very similar to each other and to well-known LL-type chondrites. Clast and matrix olivine compositions are well within the range of LL-chondrite olivine. A correlation is found between the degree of recrystallization and plagioclase composition. Petrographic observations of shocked, annealed, and unshocked clasts coupled with particle size distribution measurements indicate strongly that Kelly is similar to lunar metabreccias in mode of formation. It is theorized that Kelly is an LL-chondrite parent body metabreccia representing the final accumulation phase of the parent body.

  12. Relation of attitude toward body elimination to parenting style and attitude toward the body.

    PubMed

    Corgiat, Claudia A; Templer, Donald I

    2003-04-01

    The purpose was to estimate the relation of attitude toward body elimination in 93 college students (27 men and 66 women), to authoritarian personality features, participants' perception of their mothers' parenting style, and attitudes toward cleanliness, sex, and family nudity. Subjects were administered the Body Elimination Attitude Scale, the Four-item F Scale, the Parental Authority Questionnaire Pertaining to Mothers, and the items "Sex is dirty," "Cleanliness is next to godliness," and "Children should never see other family members nude." Larger scores for disgust toward body elimination were associated with authoritarian personality characteristics, being less likely to describe mother's parenting style as authoritative (open communication) and more likely to describe it as authoritarian and lower scores for tolerance for family nudity. Implications for further research were suggested.

  13. Relation of attitude toward body elimination to parenting style and attitude toward the body.

    PubMed

    Corgiat, Claudia A; Templer, Donald I

    2003-04-01

    The purpose was to estimate the relation of attitude toward body elimination in 93 college students (27 men and 66 women), to authoritarian personality features, participants' perception of their mothers' parenting style, and attitudes toward cleanliness, sex, and family nudity. Subjects were administered the Body Elimination Attitude Scale, the Four-item F Scale, the Parental Authority Questionnaire Pertaining to Mothers, and the items "Sex is dirty," "Cleanliness is next to godliness," and "Children should never see other family members nude." Larger scores for disgust toward body elimination were associated with authoritarian personality characteristics, being less likely to describe mother's parenting style as authoritative (open communication) and more likely to describe it as authoritarian and lower scores for tolerance for family nudity. Implications for further research were suggested. PMID:12785652

  14. 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.

  15. Frontier Mountain meteorite specimens of the acapulcoite-lodranite clan: Petrography, pairing, and parent-rock lithology of an unusual intrusive rock

    NASA Astrophysics Data System (ADS)

    Burroni, Alessandro; Folco, Luigi

    2008-04-01

    In this paper we reconstruct the heterogeneous lithology of an unusual intrusive rock from the acapulcoite-lodranite (AL) parent asteroid on the basis of the petrographic analysis of 5 small (<8.3 g) meteorite specimens from the Frontier Mountain ice field (Antarctica). Although these individual specimens may not be representative of the parent-rock lithology due to their relatively large grain size, by putting together evidence from various thin sections and literature data we conclude that Frontier Mountain (FRO) 90011, FRO 93001, FRO 99030, and FRO 03001 are paired fragments of a medium- to coarse-grained igneous rock which intrudes a lodranite and entrains xenoliths. The igneous matrix is composed of enstatite (Fs13.3 ± 0.4 Wo3.1 ± 0.2), Cr-rich augite (Fs6.1 ± 0.7 Wo42.3 ± 0.9), and oligoclase (Ab80.5 ± 3.3 Or3.2 ± 0.6). The lodranitic xenoliths show a fine-grained (average grain size 488 ± 201 μm) granoblastic texture and consist of olivine Fa9.5 ± 0.4 and Fe,Ni metal and minor amounts of enstatite Fs12.7 ± 0.4 Wo1.8 ± 0.1, troilite, chromite, schreibersite, and Ca-phosphates. Crystals of the igneous matrix and lodranitic xenoliths are devoid of shock features down to the scanning electron microscope scale. From a petrogenetic point of view, the lack of shock evidence in the lodranitic xenoliths of all the studied samples favors the magmatic rather than the impact melting origin of this rock. FRO 95029 is an acapulcoite and represents a separate fall from the AL parent asteroid, i.e., it is not a different clast entrained by the FRO 90011, FRO 93001, FRO 99030, and FRO 03001 melt, as in genomict breccias common in the meteoritic record. The specimen-to-meteorite ratio for the AL meteorites so far found at Frontier Mountain is thus 2.5.

  16. Evidence for impact induced pressure gradients on the Allende CV3 parent body: Consequences for fluid and volatile transport

    NASA Astrophysics Data System (ADS)

    Tait, Alastair W.; Fisher, Kent R.; Srinivasan, Poorna; Simon, Justin I.

    2016-11-01

    Carbonaceous chondrites, such as those associated with the Vigarano (CV) parent body, exhibit a diverse range of oxidative/reduced alteration mineralogy (McSween, 1977). Although fluids are often cited as the medium by which this occurs (Rubin, 2012), a mechanism to explain how this fluid migrates, and why some meteorite subtypes from the same planetary body are more oxidized than others remains elusive. In our study we examined a slab of the well-known Allende (CV3OxA) meteorite. Using several petrological techniques (e.g., Fry's and Flinn) and Computerized Tomography (CT) we discover it exhibits a strong penetrative planar fabric, resulting from strain partitioning among its major components: Calcium-Aluminum-rich Inclusions (CAIs) (64.5%CT) > matrix (21.5%Fry) > chondrules (17.6%CT). In addition to the planar fabric, we found a strong lineation defined by the alignment of the maximum elongation of flattened particles interpreted to have developed by an impact event. The existence of a lineation could either be non-coaxial deformation, or the result of a mechanically heterogeneous target material. In the later case it could have formed due to discontinuous patches of sub-surface ice and/or fabrics developed through prior impact compaction (MacPherson and Krot, 2014), which would have encouraged preferential flow within the target material immediately following the impact, compacting pore spaces. We suggest that structurally controlled movement of alteration fluids in the asteroid parent body along pressure gradients contributed to the formation of secondary minerals, which may have ultimately lead to the different oxidized subtypes.

  17. Early Energetic Particle Irradiation of the HED Parent Body Regolith

    NASA Technical Reports Server (NTRS)

    Bogard, D. D.; Garrison, D. H.; Rao, M. N.

    1996-01-01

    ratio on the HED parent body was probably < 0.1. The relatively large difference between the derived 21-Ne SCR/GCR ratio in Kapoeta dark feldspar and the estimated production ratio strongly indicates that the early solar irradiation involved a flux -20-50x the recent solar flux. This enhanced proton flux was probably associated with an overall greater solar activity in the first approximately 10(exp 7) to 10(exp 8) years of solar history.

  18. Laser Induced Breakdown Spectroscopy applications to meteorites: Chemical analysis and composition profiles

    NASA Astrophysics Data System (ADS)

    Dell'Aglio, M.; De Giacomo, A.; Gaudiuso, R.; Pascale, O. De; Senesi, G. S.; Longo, S.

    2010-12-01

    A fast procedure for chemical analysis of different meteorites is presented, based on LIBS (Laser Induced Breakdown Spectroscopy). The technique is applied to several test cases (Dhofar 019, Dhofar 461, Sahara 98222, Toluca, Sikhote Alin and Campo del Cielo) and can be useful for rapid meteorite identification providing geologists with specific chemical information for meteorite classification. Concentration profiles of Fe, Ni and Co are simultaneously detected across the Widmanstätten structure of the iron meteorite Toluca with a view to determining cooling rates. The LIBS analysis of meteorites is also used as a laboratory test for analogous studies on the respective parent bodies (Mars, asteroids) in space exploration missions where one clear advantage of the proposed technique is that no direct contact with the sample is required.

  19. Experimental study of segregation in plane front solidification and its relevance to iron meteorite solidification

    NASA Astrophysics Data System (ADS)

    Sellamuthu, R.; Goldstein, J. I.

    1983-11-01

    A directional solidification technique was developed and applied to the problem of fractional crystallization of an iron meteorite parent body. Samples of Fe-Ni alloys close to meteorite compositions and containing S, P, and C were made. The solidified structures contain secondary phases such as sulphides within the pro-eutectic single crystal austenite (taenite). As a result of these experiments, we propose that the secondary phases observed in iron meteorites were formed during primary solidification of austenite (taenite). The measured composition profiles of Ni, P and C in the alloys were used to explain the elemental distribution within a chemical group of iron meteorites. An analytical procedure was applied to determine the equilibrium distribution coefficients as a function of fraction solidified for Ni and P from the composition profiles. The distribution coefficients of Ni and P agree with previous values. These distribution coefficients are of particular interest in the determination of the elemental distributions in iron meteorites.

  20. Cosmogenic-radionuclide Profile of the Mocs Meteorite Strewnfield

    NASA Astrophysics Data System (ADS)

    Ferko, T. E.; Lipschutz, M. E.

    1996-03-01

    Cosmic-ray produced nuclides were measured in samples from eight pieces of the L5-6 chondrite Mocs from known locations in the strewnfield. We measured 10Be and 26Al in the bulk phase along with 36Cl in both the metal and silicate phases. Relationships of the activities of these radionuclides from various meteorite pieces in the Mocs strewnfield provide new insight into the association of meteorite fragments to each other in the pre-atmospheric parent body. Results suggest a >2pi irradiation for the Mocs meteoroid which was less than 1 meter in radius.

  1. The Glanerbrug Breccia: Evidence for a Separate L/LL-Chondritic Parent Body?

    NASA Astrophysics Data System (ADS)

    Welten, K. C.; Lindner, L.; Poorter, R. P. E.; Kallemeyn, G. W.; Rubin, A. E.; Wasson, J. T.

    1992-07-01

    INTRODUCTION. On April 7, 1990, a brecciated ordinary chondrite fell through the roof of a house near Glanerbrug in the Netherlands and was shattered to pieces. The total weight of the recovered fragments was about 800 g, the largest piece weighing 135 g. This main fragment clearly shows the inhomogeneous structure of the Glanerbrug: a dark-grey breccia occasionally containing blackish inclusions, separated from a light-grey breccia by a sharp boundary. Chondrules seem to be more common in the light grey parts. On the basis of earlier electron microprobe analyses of olivines and pyroxenes the light-grey portion was classified at the high Fa-Fs end of the L-field and the dark-grey part at the high Fa-Fs end of the LL-field [1]. Since it is not likely that the L and LL chondritic fragments originated on a single parent body, two alternative explanations were suggested: (i) The light-dark structure of the Glanerbrug is a characteristic feature of regolithic breccias, which once resided on or close to the surface of its parent body [2]. This lends some support to the idea that the light portion is an exotic clast in a dark host rock or vice versa; (ii) the two lithologies represent materials of a body having compositions between L and LL tentatively designated as L/LL [3,4]. Therefore additional electron microprobe analyses (EPMA) of silicates and kamacites in combination with neutron-activation analyses (INAA) of a light and a dark fragment and a noble gas analysis of a mixed light-dark fragment were undertaken. RESULTS and DISCUSSION. The light lithology in two thin sections shows olivine compositions in the L range (24.5+-0.3% Fa) and kamacite compositions (13.0+-1.3 mg/g Co) close to the LL range, plotting in the L/LL rather than in the L field on a kamacite-Co vs. olivine-Fa diagram [3,4]. Whereas only one aberrant olivine grain (out of 50) was found in the light portion, the dark portion is less homogeneous: one thin section shows olivine and kamacite

  2. Actual Body Weight and the Parent's Perspective of Child's Body Weight among Rural Canadian Children.

    PubMed

    Karunanayake, Chandima P; Rennie, Donna C; Hildebrand, Carole; Lawson, Joshua A; Hagel, Louise; Dosman, James A; Pahwa, Punam; The Saskatchewan Rural Health Study Team

    2016-01-01

    The prevalence of being overweight during childhood continues to increase in the USA and Canada and children living in rural areas are more at risk than their urban counterparts. The objectives of this study were to evaluate how well the parent's perception of their child's weight status correlated with objectively measured weight status among a group of rural children and to identify predictors of inaccurate parental perceptions of child's weight status. Participants were children from the Saskatchewan Rural Health Study conducted in 2010. Self-administered questionnaires were distributed through rural schools to parents of children in grades one to eight. Parents reported their child's height and weight and rated their child's weight status (underweight, just about the right weight, or overweight). Standardized body mass index (BMI) categories were calculated for clinically measured height and weight and for parental report of height and weight for 584 children. Logistic regression analysis was performed to identify predictors of misclassification of the parent's perception of child's weight status adjusting for potential confounders. Clinically measured overweight was much higher (26.5%) compared to parental perceived overweight (7.9%). The misclassification of the child's BMI was more likely to occur if the child was a boy (odds ratio (OR) = 1.58) or non-Caucasian (OR = 2.03). Overweight was high in this group of rural children and parental perception of weight status underestimated the actual weight status of overweight school-age children. Parental reporting of child weight status has implications for public health policy and prevention strategies. Future research should focus on assessing longitudinal effects of parental misperceptions of child's weight status. PMID:27527235

  3. Ar-39 - Ar-40 Evidence for an Approximately 4.26 Ga Impact Heating Event on the LL Parent Body

    NASA Technical Reports Server (NTRS)

    Dixon, E. T.; Bogard, D. D.; Rubin, A. E.

    2003-01-01

    Miller Range 99301 is a type 6, unbrecciated LL chondrite. MIL 99301 is of interest because some compositional and petrographic features suggest it experienced rather high shock grades, whereas other features suggest it is relatively unshocked. Inconsistent shock indicators could be explained if MIL 99301 was shocked but then partly annealed by heat produced by impacts on the parent body. The hypothesis that MIL 99301 experienced high temperature metamorphism (type 6) followed by a later shock event that heated, but did not melt, the constituent feldspar can be evaluated using (39)Ar-(40)Ar chronology. This is because (39)Ar-(40)Ar ages of shocked ordinary chondrites are generally <4.2 Ga, whereas (39)Ar-(40)Ar ages of unshocked meteorites are generally older, and between 4.52 - 4.38 Ga.

  4. 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.

  5. The evolution of partially differentiated planetesimals Evidence from iron meteorite groups IAB and IIICD

    NASA Technical Reports Server (NTRS)

    Kracher, A.

    1985-01-01

    Some of the properties of IAB and IIICD iron meteorites thought to be derived from partially differentiated planetesimals are summarized, and the physical aspects that may have controlled parent body differentiation and affected the composition of the sulfide melt are outlined. The chemical evolution of the parent body is then discussed, and observations supporting the partial differentiation model are examined. Finally, an attempt is made to reinterpret barometric and chronometric data in light of the partial differentiation model, and tentative conclusions are presented.

  6. Early Petrologic Processes on the Ureilite Parent Body

    NASA Technical Reports Server (NTRS)

    Singletary, S. J.; Grove, T. L.

    2003-01-01

    We present a petrographic and petrologic analysis of 21 olivine-pigeonite ureilites, along with new experimental results on melt compositions predicted to be in equilibrium with ureilite compositions. We conclude that these ureilites are the residues of a partial melting/smelting event. Textural evidence preserved in olivine and pigeonite record the extent of primary smelting. In pigeonite cores, we observe fine trains of iron metal inclusions that formed by the reduction of olivine to pigeonite and metal during primary smelting. Olivine cores lack metal inclusions but the outer grain boundaries are variably reduced by a late-stage reduction event. The modal proportion of pigeonite and percentage of olivine affected by late stage reduction are inversely related and provide an estimation of the degree of primary smelting during ureilite petrogenesis. In our sample suite, this correlation holds for 16 of the 21 samples examined. Olivine-pigeonite-liquid phase equilibrium constraints are used to obtain temperature estimates for the ureilite samples examined. Inferred smelting temperatures range from approximately 1150 C to just over 1300 C and span the range of estimates published for ureilites containing two or more pyroxenes. Temperature is also positively correlated with modal percent pigeonite. Smelting temperature is inversely correlated with smelting depth--the hottest olivine-pigeonite ureilites coming from the shallowest depth in the ureilite parent body. The highest temperature samples also have oxygen isotopic signatures that fall toward the refractory inclusion-rich end of the carbonaceous chondrite-anhydrous mineral (CCAM) slope 1 mixing line. These temperature-depth variations in the ureilite parent body could have been created by a heterogeneous distribution of heat producing elements, which would indicate that isotopic heterogeneities existed in the material from which the ureilite parent body was assembled.

  7. The thickness of eucritic crust in the HED parent body

    NASA Technical Reports Server (NTRS)

    Miyamoto, M.; Takeda, H.

    1993-01-01

    Because cumulate eucrites are generally thought to be located at the lower part in eucritic crust on a diogenitic mantle in the HED parent body, the burial depth of cumulate eucrites gives information on the thickness of the eucritic crust. We estimated the burial depth and cooling rate of cumulate eucrites, Serra de Mage and Moore County on the basis of the width of augite lamellae and compositional gradients of Ca in pyroxenes by numerically solving the diffusion equation. We obtained the burial depth of the eucrites of 7-8 km and cooling rate of 0.00016-0.0002 degrees C/yr.

  8. Chemical compositions of the moon, earth, and eucrite parent body

    NASA Technical Reports Server (NTRS)

    Anders, E.

    1977-01-01

    Model compositions of the moon and earth were calculated on the assumption that these planets had experienced chondrite-like nebular fractionation processes. The model correctly predicts the abundance ratios of certain volatile/refractory element pairs (e.g., Cd/Ba, Ga/La, Sn/Th, and Pb/U), the density of the moon, and the major rock types. The model is also used to reconstruct the composition of the parent eucrite body, which resembles the moon except for a lower content of refractory elements.

  9. Cosmic-ray Exposure Ages of Meteorites

    NASA Astrophysics Data System (ADS)

    Herzog, G. F.

    2003-12-01

    The classic idea of a cosmic-ray exposure (CRE) age for a meteorite is based on a simple but useful picture of meteorite evolution, the one-stage irradiation model. The precursor rock starts out on a parent body, buried under a mantle of material many meters thick that screens out cosmic rays. At a time ti, a collision excavates a precursor rock - a "meteoroid." The newly liberated meteoroid, now fully exposed to cosmic rays, orbits the Sun until a time tf, when it strikes the Earth, where the overlying blanket of air (and possibly of water or ice) again shuts out almost all cosmic rays (cf. Masarik and Reedy, 1995). The quantity tf-ti is called the CRE age, t. To obtain the CRE age of a meteorite, we measure the concentrations in it of one or more cosmogenic nuclides (Table 1), which are nuclides that cosmic rays produce by inducing nuclear reactions. Many shorter-lived radionuclides excluded from Table 1 such as 22Na (t1/2=2.6 yr) and 60Co (t1/2=5.27 yr) can also furnish valuable information, but can be measured only in meteorites that fell within the last few half-lives of those nuclides (see, e.g., Leya et al. (2001) and references therein). Table 1. Cosmogenic nuclides used for calculating exposure ages NuclideHalf-lifea (Myr) Radionuclides 14C0.005730 59Ni0.076 41Ca0.1034 81Kr0.229 36Cl0.301 26Al0.717 10Be1.51 53Mn3.74 129I15.7 Stable nuclides 3He 21Ne 38Ar 83Kr 126Xe a http://www2.bnl.gov/ton. CRE ages have implications for several interrelated questions. From how many different parent bodies do meteorites come? How well do meteorites represent the population of the asteroid belt? How many distinct collisions on each parent body have created the known meteorites of each type? How often do asteroids collide? How big and how energetic were the collisions that produced meteoroids? What factors control the CRE age of a meteorite and how do meteoroid orbits evolve through time? We will touch on these questions below as we examine the data.By 1975, the CRE ages of

  10. Meteoroids and Meteors - Observations and Connection to Parent Bodies

    NASA Astrophysics Data System (ADS)

    Abe, Shinsuke

    2009-05-01

    Meteoroid are a small rocky bodies traveling through interplanetary space. Meteors are phenomena caused by the interaction of meteoroids with the Earth's upper atmosphere. In this chapter the author, will briefly discuss observational methods and then concentrate on optical observations of meteors. First, the basic properties of meteor phenomenon in the atmosphere and classification of meteoroids are introduced and then coincidental phenomena, e.g., wake, jets, and train, are mentioned. Scientific observations (imaging and spectroscopy) carried out using various observational techniques allow measuring characteristics of meteoroids, e.g., orbits, density, strength, compositions. All information are potentially useful for investigating parent bodies of meteoroids, such as comets and asteroids. Searching for organics-related CHON and water in meteoroids is of particular interest for astrobiology.

  11. Mineralogy and chemistry of planets and meteorites

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The data collection and the interpretation with respect to the mineralogy of meteoritic and terrestrial samples are summarized. The key conclusion is that the Moon underwent a series of melting episodes with complex crystal-liquid differentiation. It was not possible to determine whether the Moon melted completely or only partially. The stage is now set for a systematical geochemical and geophysical survey of the Moon. Emphasis was moved to meteorites in order to sort out their interrelationships from the viewpoint of mineral chemistry. Several parent bodies are needed for the achondrites with different chemical properties. Exploration of Mars is required to test ideas based on the possible assignment of shergottites, nakhlites and chassignite to this planet. Early rocks on the Earth have properties consistent with a heavy bombardment and strong volcanic activity prior to 4 billion years ago.

  12. The Cooling History and Structure of the Ordinary Chondrite Parent Bodies

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

    Most major meteorite classes exhibit significant ranges of metamorphism. The effects of metamorphism have been extensively characterized, but the heat source(s) and the metamorphic environment are unknown. Proposed beat sources include Al-26, Fe-60, electromagnetic induction, and impact. It is typically assumed that metamorphism occurred in parent bodies of some sort, but it uncertain whether these bodies were highly structured ("onion skins") or were chaotic mixes of material ("rubble piles"). The lack of simple trends of metallographic cooling rates with petrologic type has been considered supportive of both concepts. In this study, we use induced thermoluminescence (TL) as an indicator of thermal history. The TL of ordinary chondrites is produced by sodic feldspar, and the induced TL peak temperature is related to its crystallographic order/disorder. Ordered feldspar has TL peak temperatures of approx. 120 C, and disordered feldspar has TL peak temperatures of approx. 220 C. While ordered feldspar can be easily disordered in the laboratory by heating above 650 C and is easily quenched in the disordered form, producing ordered feldspar requires cooling at geologic cooling rates. We have measured the induced TL properties of 101 equilibrated ordinary chondrites, including 49 H, 29 L, and 23 LL chondrites. For the H chondrites there is an apparent trend of decreasing induced TL peak temperature with increasing petrologic type. H4 chondrites exhibit a tight range of TL peak temperatures, 190 C - 200 C, while H6 chondrites exhibit TL peak temperatures between 180 C and 190 C. H5 chondrites cover the range between H4 and H6, and also extend up to 210 C. Similar results are obtained for LL chondfiles and most L6 chondrites have lower induced TL peak temperatures than L5 chondrites.

  13. Don Quixote --- a possible parent body of a meteor shower

    NASA Astrophysics Data System (ADS)

    Rudawska, R.; Vaubaillon, J.

    2014-07-01

    This talk addresses the topic of meteoroid stream parent body in relation to meteor showers observed on the Earth. We carry out a further search to investigate the possibility of meteor shower observations caused by particles ejected from (3552) Don Quixote. The (3552) Don Quixote asteroid was discovered in 1983 as an Amor asteroid. The Tisserand parameter for the orbit has a value of 2.315 with respect to Jupiter, which indicates a comet-like orbit. The diameter of the object calculated from the absolute magnitude, is in the range of 12.3--24.5 km. It all makes Don Quixote a good candidate for a short-period comet among known near-Earth objects, which the recently observed cometary activity confirms [1]. We have investigated the orbital evolution of the meteoroid stream originated from Don Quixote. If the object was active in the past, it might be a parent body for a meteor shower observed on the Earth. The model for the generation and evolution of the meteoroid stream in the Solar System is taken from [2]. The asteroid's orbital elements and physical properties are taken from the JPL horizons website. The ejections of meteoroids from the asteroid surface took place when the asteroid was passing its perihelion between 5000 B.C. and 2013 A.D. Next, the orbits of ejected meteoroids were integrated to the year 2050. If a meteoroid is sufficiently close to the Earth, its orbital parameters are saved and compared with known showers.

  14. 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.

  15. Comets, Carbonaceous Meteorites, and the Origin of the Biosphere

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.

    2007-01-01

    Evidence for indigenous microfossils in carbonaceous meteorites suggests that the paradigm of the endogenous origin of life on Earth should be reconsidered. It is now widely accepted that comets and carbonaceous meteorites played an important role in the delivery of water, organics and life critical biogenic elements to the early Earth and facilitated the origin and evolution of the Earth's Biosphere. However; the detection of embedded microfossils and mats in carbonaceous meteorites implies that comets and meteorites may have played a direct role in the delivery of intact microorganisms and that the Biosphere may extend far into the Cosmos. Recent space observations have found the nuclei of comets to have very low albedos (approx.0.03) and. these jet-black surfaces become very hot (T approx. 400 K) near perihelion. This paper reviews recent observational data-on comets and suggests that liquid water pools could exist in cavities and fissures between the internal ices and rocks and the exterior carbonaceous crust. The presence of light and liquid water near the surface of the nucleus enhances the possibility that comets could harbor prokaryotic extremophiles (e.g., cyanobacteria) capable of growth over a wide range of temperatures. The hypothesis that comets are the parent bodies of the CI1 and the CM2 carbonaceous meteorites is advanced. Electron microscopy images will be presented showing forms interpreted as indigenous-microfossils embedded' in freshly. fractured interior surfaces of the Orgueil (CI1) and Murchison (CM2) meteorites. These forms are consistent in size and morphologies with known morphotypes of all five orders of Cyanobacteriaceae: Energy Dispersive X-ray Spectroscopy (EDS) elemental data shows that the meteoritic forms have anomalous C/O; C/N; and C/S as compared with modern extremophiles and cyanobacteria. These images and spectral data indicate that the clearly biogenic and embedded remains cannot be interpreted as recent biological

  16. Water in SNC meteorites: evidence for a martian hydrosphere.

    PubMed

    Karlsson, H R; Clayton, R N; Gibson, E K; Mayeda, T K

    1992-03-13

    The Shergotty-Nakhla-Chassigny (SNC) meteorites, purportedly of martian origin, contain 0.04 to 0.4 percent water by weight. Oxygen isotopic analysis can be used to determine whether this water is extraterrestrial or terrestrial. Such analysis reveals that a portion of the water is extraterrestrial and furthermore was not in oxygen isotopic equilibrium with the host rock. Lack of equilibrium between water and host rock implies that the lithosphere and hydrosphere of the SNC parent body formed two distinct oxygen isotopic reservoirs. If Mars was the parent body, the maintenance of two distinct reservoirs may result from the absence of plate tectonics on the planet.

  17. High-pressure experiments on magnesian eucrite compositions - Constraints on magmatic processes in the eucrite parent body

    NASA Technical Reports Server (NTRS)

    Bartels, K. S.; Grove, T. L.

    1991-01-01

    Melting experiments were conducted on synthetic analogs of two magnesian eucrite clasts from howardites, Kapoeta clast rho and Yamato 7308 pigeonite-eucrite clast 1, at 1 atm and 1-kbar pressure at oxygen fugacities in the range of iron-wuestite (IW) to iron-quartz-fayalite (IQF). The compositions of liquids and coexisting minerals (olivine-low-Ca pyroxene-plagioclase spinel) were used to constrain possible melting and crystallization processes in the parent bodies of eucrite basalts. In agreement with previous studies, the experimental results at 1 atm indicate that the olivine-low-Ca pyroxene-plagioclase-spinel-liquid and olivine-low Ca pyroxene-spinel-liquid boundaries are reaction boundaries involving olivine. At 1 kbar, however, the olivine primary-phase volume shrinks, and the reaction relationship involving olivine disappears for both boundaries. The maximum pressure attained in a Vesta-sized eucrite parent body (EPB) is about 1 kbar, and these results provide important constraints on models relating the howardite-eucrite-diogenite (HED) meteorite association through melting and differentiation processes.

  18. Lunar and Planetary Science XXXV: Martian Meteorites: Petrology

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session "Martian Meteorites: Petrology: included the following reports:Volatile Behavior in Lunar and Terrestrial Basalts During Shock: Implications for Martian Magmas; Problems with a Low-Pressure Tholeiitic Magmatic History for the Chassigny Dunite; Fast Cooling History of the Chassigny Martian Meteorite; Rehomogenized Interstitial and Inclusion Melts in Lherzolitic Shergottite ALH 77005: Petrologic Significance; Compositional Controls on the Formation of Kaersutite Amphibole in Shergottite Meteorites; Chemical Characteristics of an Olivine-Phyric Shergottite, Yamato 980459; Pb-Hf-Sr-Nd Isotopic Systematics and Age of Nakhlite NWA 998; Noble Gases in Two Samples of EETA 79001 (Lith. A); Experimental Constraints on the Iron Content of the Martian Mantle; and Mars as the Parent Body for the CI Carbonaceous Chondrites: New Data.

  19. Ar-Ar ages and thermal histories of enstatite meteorites

    NASA Astrophysics Data System (ADS)

    Bogard, Donald D.; Dixon, Eleanor T.; Garrison, Daniel H.

    2010-05-01

    Compared with ordinary chondrites, there is a relative paucity of chronological and other data to define the early thermal histories of enstatite parent bodies. In this study, we report 39Ar-40Ar dating results for five EL chondrites: Khairpur, Pillistfer, Hvittis, Blithfield, and Forrest; five EH chondrites: Parsa, Saint Marks, Indarch, Bethune, and Reckling Peak 80259; three igneous-textured enstatite meteorites that represent impact melts on enstatite chondrite parent bodies: Zaklodzie, Queen Alexandra Range 97348, and Queen Alexandra Range 97289; and three aubrites, Norton County, Bishopville, and Cumberland Falls Several Ar-Ar age spectra show unusual 39Ar recoil effects, possibly the result of some of the K residing in unusual sulfide minerals, such as djerfisherite and rodderite, and other age spectra show 40Ar diffusion loss. Few additional Ar-Ar ages for enstatite meteorites are available in the literature. When all available Ar-Ar data on enstatite meteorites are considered, preferred ages of nine chondrites and one aubrite show a range of 4.50-4.54Ga, whereas five other meteorites show only lower age limits over 4.35-4.46Ga. Ar-Ar ages of several enstatite chondrites are as old or older as the oldest Ar-Ar ages of ordinary chondrites, which suggests that enstatite chondrites may have derived from somewhat smaller parent bodies, or were metamorphosed to lower temperatures compared to other chondrite types. Many enstatite meteorites are brecciated and/or shocked, and some of the younger Ar-Ar ages may record these impact events. Although impact heating of ordinary chondrites within the last 1Ga is relatively common for ordinary chondrites, only Bethune gives any significant evidence for such a young event.

  20. 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.

  1. Body mass index in young adults: Associations with parental body size and education in the CARDIA Study.

    PubMed Central

    Greenlund, K J; Liu, K; Dyer, A R; Kiefe, C I; Burke, G L; Yunis, C

    1996-01-01

    OBJECTIVES: Associations of parental education, parental body size, and offspring's education with body mass index and 7-year change in body mass index were examined among participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study. METHODS: CARDIA is a study of coronary artery disease risk factors in 5115 Black and White persons aged 18 to 30 at baseline. Analyses of covariance were carried out with body mass index and change in body mass index as the dependent variables, and with parental education, parental body size, and participant education as the major independent variables. RESULTS: Father's body size was positively associated with participant's baseline body mass index among Black men, White men, and White women. Mother's body size was positively associated with baseline body mass index among all race-sex groups, and with change in body mass index among White women. Father's education was inversely associated with baseline body mass index among Black men and White women, and with change among White women. CONCLUSIONS: Parental education may influence body mass index and changes in young adulthood, especially among White women. Such associations may be both genetic and environmental and may be important for obesity prevention efforts. PMID:8604777

  2. Spectral variability on primitive asteroids of the Themis and Beagle families: Space weathering effects or parent body heterogeneity?

    NASA Astrophysics Data System (ADS)

    Fornasier, S.; Lantz, C.; Perna, D.; Campins, H.; Barucci, M. A.; Nesvorny, D.

    2016-05-01

    Themis is an old and statistically robust asteroid family populating the outer main belt, and resulting from a catastrophic collision that took place 2.5 ± 1.0 Gyr ago. Within the old Themis family a young sub-family, Beagle, formed less than 10 Myr ago, has been identified. We present the results of a spectroscopic survey in the visible and near infrared range of 22 Themis and 8 Beagle families members. The Themis members investigated exhibit a wide range of spectral behaviors, including asteroids with blue/neutral and moderately red spectra, while the younger Beagle family members look spectrally bluer than the Themis ones and they have a much smaller spectral slope variability. Four Themis members, including (24) Themis, have absorption bands centered at 0.68-0.73 μm indicating the presence of aqueously altered minerals. The best meteorite spectral analogues found for both Themis and Beagle families members are carbonaceous chondrites having experienced different degrees of aqueous alteration, prevalently CM2 but also CV3 and CI, and some of them are chondrite samples being unusual or heated. The presence of aqueous altered materials on the asteroids surfaces and the meteorite matches indicate that the parent body of the Themis family experienced mild thermal metamorphism in the past. We extended the spectral analysis including the data available in the literature on Themis and Beagle families members, and we looked for correlations between spectral behavior and physical parameters using the albedo and size values derived from the WISE data. The analysis of this larger sample confirms the spectral diversity within the Themis family and that Beagle members tend to be bluer and to have an higher albedo. The differences between the two families may be partially explained by space weathering processes, which act on these primitive surfaces in a similar way than on S-type asteroids, i.e. producing reddening and darkening. However we see several Themis members

  3. Simulation of possible regolith optical alteration effects on carbonaceous chondrite meteorites

    NASA Astrophysics Data System (ADS)

    Clark, Beth E.; Fanale, Fraser P.; Robinson, Mark S.

    1993-03-01

    As the spectral reflectance search continues for links between meteorites and their parent body asteroids, the effects of optical surface alteration processes need to be considered. We present the results of an experimental simulation of the melting and recrystallization that occurs to a carbonaceous chondrite meteorite regolith powder upon heating. As done for the ordinary chondrite meteorites, we show the effects of possible parent-body regolith alteration processes on reflectance spectra of carbonaceous chondrites (CC's). For this study, six CC's of different mineralogical classes were obtained from the Antarctic Meteorite Collection: two CM meteorites, two CO meteorites, one CK, and one CV. Each sample was ground with a ceramic mortar and pestle to powders with maximum grain sizes of 180 and 90 microns. The reflectance spectra of these powders were measured at RELAB (Brown University) from 0.3 to 2.5 microns. Following comminution, the 90 micron grain size was melted in a nitrogen controlled-atmosphere fusion furnace at an approximate temperature of 1700 C. The fused sample was immediately held above a flow of nitrogen at 0 C for quenching. Following melting and recrystallization, the samples were reground to powders, and the reflectance spectra were remeasured. The effects on spectral reflectance for a sample of the CM carbonaceous chondrite called Murchison are shown.

  4. U-Pb Dating of Zircons and Phosphates in Lunar Meteorites, Acapulcoites and Angrites

    NASA Technical Reports Server (NTRS)

    Zhou, Q.; Zeigler, R. A.; Yin, Q. Z.; Korotev, R. L.; Joliff, B. L.; Amelin, Y.; Marti, K.; Wu, F. Y.; Li, X. H.; Li, Q. L.; Lin, Y. T.; Liu, Y.; Tang, G. Q.

    2012-01-01

    Zircon U-Pb geochronology has made a great contribution to the timing of magmatism in the early Solar System [1-3]. Ca phosphates are another group of common accessory minerals in meteorites with great potential for U-Pb geochronology. Compared to zircons, the lower closure temperatures of the U-Pb system for apatite and merrillite (the most common phosphates in achondrites) makes them susceptible to resetting during thermal metamorphism. The different closure temperatures of the U-Pb system for zircon and apatite provide us an opportunity to discover the evolutionary history of meteoritic parent bodies, such as the crystallization ages of magmatism, as well as later impact events and thermal metamorphism. We have developed techniques using the Cameca IMS-1280 ion microprobe to date both zircon and phosphate grains in meteorites. Here we report U-Pb dating results for zircons and phosphates from lunar meteorites Dhofar 1442 and SaU 169. To test and verify the reliability of the newly developed phosphate dating technique, two additional meteorites, Acapulco, obtained from Acapulco consortium, and angrite NWA 4590 were also selected for this study as both have precisely known phosphate U-Pb ages by TIMS [4,5]. Both meteorites are from very fast cooled parent bodies with no sign of resetting [4,5], satisfying a necessity for precise dating.

  5. Simulation of possible regolith optical alteration effects on carbonaceous chondrite meteorites

    NASA Technical Reports Server (NTRS)

    Clark, Beth E.; Fanale, Fraser P.; Robinson, Mark S.

    1993-01-01

    As the spectral reflectance search continues for links between meteorites and their parent body asteroids, the effects of optical surface alteration processes need to be considered. We present the results of an experimental simulation of the melting and recrystallization that occurs to a carbonaceous chondrite meteorite regolith powder upon heating. As done for the ordinary chondrite meteorites, we show the effects of possible parent-body regolith alteration processes on reflectance spectra of carbonaceous chondrites (CC's). For this study, six CC's of different mineralogical classes were obtained from the Antarctic Meteorite Collection: two CM meteorites, two CO meteorites, one CK, and one CV. Each sample was ground with a ceramic mortar and pestle to powders with maximum grain sizes of 180 and 90 microns. The reflectance spectra of these powders were measured at RELAB (Brown University) from 0.3 to 2.5 microns. Following comminution, the 90 micron grain size was melted in a nitrogen controlled-atmosphere fusion furnace at an approximate temperature of 1700 C. The fused sample was immediately held above a flow of nitrogen at 0 C for quenching. Following melting and recrystallization, the samples were reground to powders, and the reflectance spectra were remeasured. The effects on spectral reflectance for a sample of the CM carbonaceous chondrite called Murchison are shown.

  6. Analysis of Chiral Carboxylic Acids in Meteorites

    NASA Technical Reports Server (NTRS)

    Burton, A. S.; Elsila, J. E.; Hein, J. E.; Aponte, J. C.; Parker, E. T.; Glavin, D. P.; Dworkin, J. P.

    2015-01-01

    Homochirality of amino acids in proteins and sugars in DNA and RNA is a critical feature of life on Earth. In the absence of a chiral driving force, however, reactions leading to the synthesis of amino acids and sugars result in racemic mixtures. It is currently unknown whether homochirality was necessary for the origins of life or if it was a product of early life. The observation of enantiomeric excesses of certain amino acids of extraterrestrial origins in meteorites provides evidence to support the hypothesis that there was a mechanism for the preferential synthesis or destruction of a particular amino acid enantiomer [e.g., 1-3]. The cause of the observed chiral excesses is un-clear, although at least in the case of the amino acid isovaline, the degree of aqueous alteration that occurred on the meteorite parent body is correlated to the isovaline L-enantiomeric excess [3, 4]. This suggests that chiral symmetry is broken and/or amplified within the meteorite parent bodies. Besides amino acids, there have been only a few reports of other meteoritic compounds found in enantiomeric excess: sugars and sugar acids [5, 6] and the hydroxy acid lactic acid [7]. Determining whether or not additional types of molecules in meteorites are also present in enantiomeric excesses of extraterrestrial information will provide insights into mechanisms for breaking chiral symmetry. Though the previous measurements (e.g., enantiomeric composition of lactic acid [7], and chiral carboxylic acids [8]) were made by gas chromatography-mass spectrometry, the potential for increased sensitivity of liquid chromatography-mass spectrometry (LC-MS) analyses is important because for many meteorite samples, only small sample masses are available for study. Furthermore, at least in the case of amino acids, many of the largest amino acid enantiomeric excesses were observed in samples that contained lower abundances (tens of ppb) of a given amino acid enantiomer. In the present work, we describe

  7. School-Based BMI and Body Composition Screening and Parent Notification in California: Methods and Messages

    ERIC Educational Resources Information Center

    Madsen, Kristine A.; Linchey, Jennifer

    2012-01-01

    Background: School-based body mass index (BMI) or body composition screening is increasing, but little is known about the process of parent notification. Since 2001, California has required annual screening of body composition via the FITNESSGRAM, with optional notification. This study sought to identify the prevalence of parental notification…

  8. Analysis of segregation trends observed in iron meteorites using measured distribution coefficients

    NASA Astrophysics Data System (ADS)

    Sellamuthu, R.; Goldstein, J. I.

    1985-02-01

    Fe-Ni alloys of meteoritic composition were solidified by a plane front solidification technique. Distribution coefficients of Ni, P, Ir, Ge, and Cu were determined from the composition data of the plane front solidified alloys. Equations that describe the distribution coefficients (P, Ni, Ir, Ge, and Cu) as a function of S and P content as well as S to P ratio were used to calculate solute partitioning between solid and liquid during the solidification of IIAB, IIIAB, and IVA parent bodies. The calculated P versus Ni, Ir versus Ni, Ge versus Ni, and Cu versus Ni trends are in good agreement with the observed meteorite data for each chemical group. It is concluded that each chemical group formed as a single molten pool in a parent body and that solute partitioning that occurred during solidification is responsible for the observed compositional trends within a single meteorite group.

  9. Asteroid-Meteorite Links: The Vesta Conundrum(s)

    NASA Technical Reports Server (NTRS)

    Pieters, C. M.; Binzel, R.; Bogard, D.; Hiroi, T.; Mittlefehldt, D. W.; Nyquist, L.; Rivkin, A.; Takeda, H.

    2006-01-01

    Although a direct link between the HED meteorites and the asteroid 4 Vesta is generally acknowledged, several issues continue to be actively examined that tie Vesta to early processes in the solar system. Vesta is no longer the only basaltic asteroid in the Main belt. In addition to the Vestoids of the Vesta family, the small asteroid Magnya is basaltic but appears to be unrelated to Vesta. Similarly, diversity now identified in the collection of basaltic meteorites requires more than one basaltic parent body, consistent with the abundance of differentiated parent bodies implied by iron meteorites. The timing of the formation of the Vestoids (and presumably the large crater at the south pole of Vesta) is unresolved. Peaks in Ar-Ar dates of eucrites suggest this impact event could be related to a possible late heavy bombardment at least 3.5 Gyr ago. On the other hand, the optically fresh appearance of both Vesta and the Vestoids requires either a relatively recent resurfacing event or that their surfaces do not weather in the same manner thought to occur on other asteroids such as the ordinary chondrite parent body. Diversity across the surface of Vesta has been observed with HST and there are hints of compositional variations (possibly involving minor olivine) in near-infrared spectra.

  10. Part 1: Aspects of lithospheric evolution on Venus. Part 2: Thermal and collisional histories of chondrite parent bodies. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Grimm, Robert E.

    1988-01-01

    The geological evolution of distinctly different kinds of solar system objects is addressed. Venus has been observed over the past decade by orbital radars on both American and Soviet spacecraft. These surface measurements provide clues to the structure and evolution of the lithosphere. The parent bodies of chondritic meteorites, thought to resemble asteroids, represent the other end of the size spectrum of terrestrial objects. Their early thermal and collisional histories may be constrained by the chemical and textural record preserved in meteorite samples. Impact craters on Venus have been observed by the Soviet Venera 15/16 spacecraft. A formalism is presented by which the size-frequency distribution of impact craters may be used to estimate upper bounds on the mean global rates of volcanic resurfacing and lithospheric recycling on that planet over the past several hundred million years. The impact crater density reported from Venera observations, if valid for the entire Venus surface, indicates a mean volcanic flux no greater than 2 cu km/y, corresponding to a maximum average rate of resurfacing of about 4 km/b.y. For the lowest estimated mean crater retention age of the surface of Venus imaged by Venera 15/16, the rate of lithospheric recycling on Venus does not exceed 1.5 sq km/y. Ordinary chondrite meteorites show textural and chemical patterns indicative of varying intensities of thermal metamorphism. The conventional onion-shell model, which envisions highly metamorphosed material in the core and less intensely heated rocks near the surface, predicts an inverse relation between peak temperature and cooking rate, but none has been observed. A metamorphosed-planetesimal model is devised to explain this discrepancy, whereby heating occurs in planetesimals a few kilometers in radius which then accrete to form 100-km-radius parent bodies. Cooling rates are then randomly controlled by burial depth. Thermal and collisional constraints are examined, and the model

  11. Crystal Structure and Chemical Composition of a Presolar Silicate from the Queen Elizabeth Range 99177 Meteorite

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

    Mineral characterization of presolar silicate grains, the most abundant stardust phase, has provided valuable information about the formation conditions in circumstellar environments and in super-nova (SN) outflows. Spectroscopic observations of dust around evolved stars suggest a majority of amor-phous, Mg-rich olivine grains, but crystalline silicates, most of which are pyroxene, have also been observed [1]. The chemical compositions of hundreds of presolar silicates have been determined by Auger spectroscopy and reveal high Fe contents and nonstoichiometric compositions intermediate to olivine and pyroxene [2-6]. The unexpectedly high Fe contents can partly be attributed to secondary alteration on the meteorite parent bodies, as some grains have Fe isotopic anomalies from their parent stellar source [7]. Only about 35 presolar silicates have been studied for their mineral structures and chemical compositions by transmission electron microscopy (TEM). These grains display a wide range of compositions and structures, including crystalline forsterite, crystalline pyroxene, nanocrystalline grains, and a majority of amorphous nonstoichiometric grains. Most of these grains were identified in the primitive Acfer 094 meteorite. Presolar silicates from this meteorite show a wide range of Fe-contents, suggestive of secondary processing on the meteorite parent body. The CR chondrite QUE 99177 has not suffered as much alteration [8] and displays the highest presolar silicate abundance to date among carbonaceous chondrites [3, 6]. However, no mineralogical studies of presolar silicates from this meteorite have been performed. Here we examine the mineralogy of a presolar silicate from QUE 99177.

  12. Iron Meteorite

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    A meteorite composed mainly of nickel-iron, with traces of other metals; also referred to simply as an iron, and formerly known as a siderite. Irons account for over 6% of all known meteorite specimens. They are the easiest type to identify, being heavy, magnetic and rust-colored; their metallic sheen tarnishes quickly on the Earth's surface, but otherwise irons show better resistance to weatheri...

  13. Cliftonite: A proposed origin, and its bearing on the origin of diamonds in meteorites

    USGS Publications Warehouse

    Brett, R.; Higgins, G.T.

    1969-01-01

    Cliftonite, a polycrystalline aggregate of graphite with spherulitic structure and cubic morphology, is known in 14 meteorites. Some workers have considered it to be a pseudomorph after diamond, and have used the proposed diamond ancestry as evidence of a meteoritic parent body of at least lunar dimensions. Careful examination of meteoritic samples indicates that cliftonite forms by precipitation within kamacite. We have also demonstrated that graphite with cubic morphology may be synthesized in a Fe-Ni-C alloy annealed in a vacuum. We therefore suggest that a high pressure origin is unnecessary for meteorities which contain cliftonite, and that these meteorities were formed at low pressures. This conclusion is in agreement with other recent evidence. We also suggest that recently discovered cubes and cubo-octahedra of lonsdaleite in the Canyon Diablo meteorite are pseudomorphs after cliftonite, not diamond, as has previously been suggested. ?? 1969.

  14. The isotopic composition of silver and lead in two iron meteorites - Cape York and Grant

    NASA Technical Reports Server (NTRS)

    Chen, J. H.; Wasserburg, G. J.

    1983-01-01

    Anomalies in silver isotope composition in the metal phases of the Cape York (IIIA) and Grant (IIIB) iron meteorites are studied together with the lead isotopic composition of both the metal and sulfide phases of Cape York. Following extensive surface cleaning, the Ag-107/Ag-109 ratio in the metal phases of the meteorites is found to be in excess of the terrestrial ratio, and of that found in the sulfide phases. A definite correlation between the Ag-107/Ag-109 and Pd-108/Ag-109 ratios is observed for these meteorites, indicating the in situ decay of Pd-107 and supporting the widespread presence of Pd in the early universe. Lead, determined after cleaning and with chemical separations using low blank levels, is found to exist in variable proportions in the metal and sulfide phases. The sulfides appear to be dominated by radiogenic modern lead, which may be explained by terrestrial contamination or by late metamorphism in the meteorite parent body.

  15. LREE variability in CM matrices: Another look at meteorite compaction ages

    NASA Technical Reports Server (NTRS)

    Woolum, Dorothy S.; Poelstra, Karen; Alexander, C.; Ireland, T.

    1993-01-01

    Recent Neon-21 analyses indicate that individual grains in some CM meteorites show the effects of enhanced exposures to energetic particles beyond that which can be attributed to conventional cosmic ray exposure. The exposures clearly occurred prior to the final compaction of the CM meteorites. These exposures were of such a magnitude that they require that we either have to revise our understanding of regolith dynamics and the time scales involved in the regolith activity of meteorite parent bodies, or must invoke an exposure of the irradiated grains to an enhanced energetic particle environment, an environment which would most likely be produced by an early active sun. Constraints on the compaction ages of the meteorites which exhibit the large precompaction exposures could play a critical role in resolving this issue.

  16. The Acapulco meteorite - Chemistry, mineralogy and irradiation effects

    NASA Astrophysics Data System (ADS)

    Palme, H.; Schultz, L.; Spettel, B.; Weber, H. W.; Wanke, H.; Michel-Levy, M. C.; Lorin, J. C.

    1981-05-01

    The mineralogy, chemical composition and radiation exposure history of the Acapulco meteorite, an object with a chondritic composition but achondritic texture which fell in August, 1976, are investigated. Sections of the meteorite were examined by optical and scanning electron microscopy and analyzed by electron microprobe and X-ray energy dispersive analysis; bulk samples were analyzed to yield concentrations of 50 elements, as well as light and heavy rare gas components and cosmic ray and fission track densities. A high degree of recrystallization and the mineral composition indicate meteorite formation under redox conditions intermediate between those of H and E chondrites at 1100 C, with cooling at a rate greater than 10 C/million years. The major element composition is within the range of H chondrites, however depletions in chalcophile elements and enrichments in Cr, P, U, light rare earth elements, volatile elements, planetary noble gases, and refractory siderophile are found. An old K-Ar age (4.7 billion years) and high Pu-244 track densities suggest that Acapulco may represent a rock formed in the early stages of melting of a chondritic parent body. Oxygen isotope and chemical data are then used to distinguish three groups of such reduced chondritic meteorites, comprising: (1) Acapulco, Lodran and Allan Hills A 77081; (2) Pontlyfini, Mount Morris, Winona and silicate inclusions in IAB meteorites; and (3) Kakangari.

  17. Molecular asymmetry in extraterrestrial chemistry: Insights from a pristine meteorite.

    PubMed

    Pizzarello, Sandra; Huang, Yongsong; Alexandre, Marcelo R

    2008-03-11

    The nonracemic amino acids of meteorites provide the only natural example of molecular asymmetry measured so far outside the biosphere. Because extant life depends on chiral homogeneity for the structure and function of biopolymers, the study of these meteoritic compounds may offer insights into the establishment of prebiotic attributes in chemical evolution as well as the origin of terrestrial homochirality. However, all efforts to understand the origin, distribution, and scope of these amino acids' enantiomeric excesses (ee) have been frustrated by the ready exposure of meteorites to terrestrial contaminants and the ubiquitous homochirality of such contamination. We have analyzed the soluble organic composition of a carbonaceous meteorite from Antarctica that was collected and stored under controlled conditions, largely escaped terrestrial contamination and offers an exceptionally pristine sample of prebiotic material. Analyses of the meteorite diastereomeric amino acids alloisoleucine and isoleucine allowed us to show that their likely precursor molecules, the aldehydes, also carried a sizable molecular asymmetry of up to 14% in the asteroidal parent body. Aldehydes are widespread and abundant interstellar molecules; that they came to be present, survived, and evolved in the solar system carrying ee gives support to the idea that biomolecular traits such as chiral asymmetry could have been seeded in abiotic chemistry ahead of life. PMID:18310323

  18. Effects of parental comments on body dissatisfaction and eating disturbance in young adults: a sociocultural model.

    PubMed

    Rodgers, Rachel F; Paxton, Susan J; Chabrol, Henri

    2009-06-01

    This study examined a sociocultural model of the influence of parental comments on body shape and eating concerns among males and females. Questionnaires were completed by 338 undergraduates. Participants reported levels of perceived parental comments, internalization of media ideals, appearance comparison, body dissatisfaction, drive for thinness and bulimia. Results revealed that, regardless of gender, internalization and appearance comparison only partially mediated the relationship between parental comments and the outcome variables. The final model for females explained a larger proportion of the variability in body shape and eating concerns than in males, with positive and negative parental comments directly related to body dissatisfaction and through it to eating outcomes. In males, only negative comments were directly related to body dissatisfaction. These findings highlight the role of parental influences in sociocultural models of the development of body dissatisfaction and eating concerns, and the gender-specific patterns of sociocultural influence.

  19. Parent Reactions to a School-Based Body Mass Index Screening Program

    ERIC Educational Resources Information Center

    Johnson, Suzanne Bennett; Pilkington, Lorri L.; Lamp, Camilla; He, Jianghua; Deeb, Larry C.

    2009-01-01

    Background: This study assessed parent reactions to school-based body mass index (BMI) screening. Methods: After a K-8 BMI screening program, parents were sent a letter detailing their child's BMI results. Approximately 50 parents were randomly selected for interview from each of 4 child weight-classification groups (overweight, at risk of…

  20. Seeding the Pregenetic Earth: Meteoritic Abundances of Nucleobases and Potential Reaction Pathways

    NASA Astrophysics Data System (ADS)

    Pearce, Ben K. D.; Pudritz, Ralph E.

    2015-07-01

    Carbonaceous chondrites are a class of meteorite known for having high contents of water and organics. In this study, the abundances of the nucleobases, i.e., the building blocks of RNA and DNA, found in carbonaceous chondrites are collated from a variety of published data and compared across various meteorite classes. An extensive review of abiotic chemical reactions producing nucleobases is then performed. These reactions are then reduced to a list of 15 individual reaction pathways that could potentially occur within meteorite parent bodies. The nucleobases guanine, adenine, and uracil are found in carbonaceous chondrites in amounts of 1–500 ppb. It is currently unknown which reaction is responsible for their synthesis within the meteorite parent bodies. One class of carbonaceous meteorite dominates the abundances of both amino acids and nucleobases—the so-called CM2 (e.g., Murchison meteorite). CR2 meteorites (e.g., Graves Nunataks) also dominate the abundances of amino acids, but are the least abundant in nucleobases. The abundances of total nucleobases in these two classes are 330 ± 250 and 16 ± 13 ppb, respectively. Guanine most often has the greatest abundances in carbonaceous chondrites with respect to the other nucleobases, but is 1–2 orders of magnitude less abundant in CM2 meteorites than glycine (the most abundant amino acid). Our survey of the reaction mechanisms for nucleobase formation suggests that Fischer–Tropsch synthesis (i.e., CO, H2, and NH3 gases reacting in the presence of a catalyst such as alumina or silica) is the most likely candidate for conditions that characterize the early states of planetesimals.

  1. Seeding the Pregenetic Earth: Meteoritic Abundances of Nucleobases and Potential Reaction Pathways

    NASA Astrophysics Data System (ADS)

    Pearce, Ben K. D.; Pudritz, Ralph E.

    2015-07-01

    Carbonaceous chondrites are a class of meteorite known for having high contents of water and organics. In this study, the abundances of the nucleobases, i.e., the building blocks of RNA and DNA, found in carbonaceous chondrites are collated from a variety of published data and compared across various meteorite classes. An extensive review of abiotic chemical reactions producing nucleobases is then performed. These reactions are then reduced to a list of 15 individual reaction pathways that could potentially occur within meteorite parent bodies. The nucleobases guanine, adenine, and uracil are found in carbonaceous chondrites in amounts of 1-500 ppb. It is currently unknown which reaction is responsible for their synthesis within the meteorite parent bodies. One class of carbonaceous meteorite dominates the abundances of both amino acids and nucleobases—the so-called CM2 (e.g., Murchison meteorite). CR2 meteorites (e.g., Graves Nunataks) also dominate the abundances of amino acids, but are the least abundant in nucleobases. The abundances of total nucleobases in these two classes are 330 ± 250 and 16 ± 13 ppb, respectively. Guanine most often has the greatest abundances in carbonaceous chondrites with respect to the other nucleobases, but is 1-2 orders of magnitude less abundant in CM2 meteorites than glycine (the most abundant amino acid). Our survey of the reaction mechanisms for nucleobase formation suggests that Fischer-Tropsch synthesis (i.e., CO, H2, and NH3 gases reacting in the presence of a catalyst such as alumina or silica) is the most likely candidate for conditions that characterize the early states of planetesimals.

  2. Extraterrestrial amino acids in the Almahata Sitta meteorite

    NASA Astrophysics Data System (ADS)

    Glavin, Daniel P.; Aubrey, Andrew D.; Callahan, Michael P.; Dworkin, Jason P.; Elsila, Jamie E.; Parker, Eric T.; Bada, Jeffrey L.; Jenniskens, Peter; Shaddad, Muawia H.

    2010-10-01

    Amino acid analysis of a meteorite fragment of asteroid 2008 TC3 called Almahata Sitta was carried out using reverse-phase liquid chromatography coupled with UV fluorescence detection and time-of-flight mass spectrometry (LC-FD/ToF-MS) as part of a sample analysis consortium. LC-FD/ToF-MS analyses of hot-water extracts from the meteorite revealed a complex distribution of two- to seven-carbon aliphatic amino acids and one- to three-carbon amines with abundances ranging from 0.5 to 149 parts-per-billion (ppb). The enantiomeric ratios of the amino acids alanine, β-amino-n-butyric acid, 2-amino-2-methylbutanoic acid (isovaline), and 2-aminopentanoic acid (norvaline) in the meteorite were racemic (D/L ˜ 1), indicating that these amino acids are indigenous to the meteorite and not terrestrial contaminants. Several other nonprotein amino acids were also identified in the meteorite above background levels including α-aminoisobutyric acid (α-AIB), 4-amino-2-methylbutanoic acid, 4-amino-3-methylbutanoic acid, and 3-, 4-, and 5-aminopentanoic acid. The total abundances of isovaline and α-AIB in Almahata Sitta are approximately 1000 times lower than the abundances of these amino acids found in the CM carbonaceous chondrite Murchison. The extremely low abundances and unusual distribution of five-carbon amino acids in Almahata Sitta compared to CI, CM, and CR carbonaceous chondrites may reflect extensive thermal alteration of amino acids on the parent asteroid by partial melting during formation or subsequent impact shock heating. It is also possible that amino acids were synthesized by catalytic reactions on the parent body after asteroid 2008 TC3 cooled to lower temperatures, or introduced as a contaminant from unrelated meteorite clasts and chemically altered by α-decarboxylation.

  3. Geochemistry of Martian Meteorites and the Petrologic Evolution of Mars

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, D. W.

    2002-01-01

    Mafic igneous rocks serve as probes of the interiors of their parent bodies - the compositions of the magmas contain an imprint of the source region composition and mineralogy, the melting and crystallization processes, and mixing and assimilation. Although complicated by their multifarious history, it is possible to constrain the petrologic evolution of an igneous province through compositional study of the rocks. Incompatible trace elements provide one means of doing this. I will use incompatible element ratios of martian meteorites to constrain the early petrologic evolution of Mars. Incompatible elements are strongly partitioned into the melt phase during igneous processes. The degree of incompatibility will differ depending on the mineral phases in equilibrium with the melt. Most martian meteorites contain some cumulus grains, but nevertheless, incompatible element ratios of bulk meteorites will be close to those of their parent magmas. ALH 84001 is an exception, and it will not be discussed. The martian meteorites will be considered in two groups; a 1.3 Ga group composed of the clinopyroxenites and dunite, and a younger group composed of all others.

  4. Magnetic remanence in the Murchison meteorite

    NASA Astrophysics Data System (ADS)

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

    2003-03-01

    The Murchison meteorite is a carbonaceous chondrite containing a small amount of chondrules, various inclusions, and matrix with occasional porphyroblasts of olivine and/or pyroxene. It also contains amino acids that may have served as the necessary components for the origin of life. Magnetic analyses of Murchison identify an ultrasoft magnetic component due to superparamagnetism as a significant part of the magnetic remanence. The rest of the remanence may be due to electric discharge in the form of lightning bolts that may have formed the amino acids. The level of magnetic remanence does not support this possibility and points to a minimum ambient field of the remanence acquisition. We support our observation by showing that normalized mineral magnetic acquisition properties establish a calibration curve suitable for rough paleofield determination. When using this approach, 1­2% of the natural remanence left in terrestrial rocks with TRM and/or CRM determines the geomagnetic field intensity irrespective of grain size or type of magnetic mineral (with the exception of hematite). The same method is applied to the Murchison meteorite where the measured meteorite remanence determines the paleofield minimum intensity of 200­2000 nT during and/or after the formation of the parent body.

  5. Aqueous Alteration and Hydrogen Generation on Parent Bodies of Unequilibrated Ordinary Chondrites: Thermodynamic Modeling for the Semarkona Composition

    NASA Technical Reports Server (NTRS)

    Zolotov, M. Y.; Mironenko, M. V.; Shock, E. L.

    2005-01-01

    Ordinary chondrites are the most abundant class of meteorites that could represent rocky parts of solar system bodies. However, even the most primitive unequilibrated ordinary chondrites (UOC) reveal signs of mild alteration that affected the matrix and peripheral zones of chondrules. Major chemical changes include oxidation of kamacite, alteration of glass, removal of alkalis, Al, and Si from chondrules, and formation of phases enriched in halogens, alkalis, and hydrogen. Secondary mineralogical changes include formation of magnetite, ferrous olivine, fayalite, pentlandite, awaruite, smectites, phosphates, carbonates, and carbides. Aqueous alteration is consistent with the oxygen isotope data for magnetite. The presence of secondary magnetite, Ni-rich metal alloys, and ferrous silicates in UOC implies that H2O was the oxidizing agent. However, oxidation by H2O means that H2 is produced in each oxidative pathway. In turn, production of H2, and its redistribution and possible escape should have affected total pressure, as well as the oxidation state of gas, aqueous and mineral phases in the parent body. Here we use equilibrium thermodynamic modeling to explore water-rock reactions in UOC. The chemical composition of gas, aqueous, and mineral phases is considered.

  6. The oxygen isotope evolution of parent body aqueous solutions as recorded by multiple carbonate generations in the Lonewolf Nunataks 94101 CM2 carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Lee, M. R.; Sofe, M. R.; Lindgren, P.; Starkey, N. A.; Franchi, I. A.

    2013-11-01

    The CM2 carbonaceous chondrite LON 94101 contains aragonite and two generations of calcite that provide snapshots of the chemical and isotopic evolution of aqueous solutions during parent body alteration. Aragonite was the first carbonate to crystallize. It is rare, heterogeneously distributed within the meteorite matrix, and its mean oxygen isotope values are δ18O 39.9 ± 0.6‰, Δ17O -0.3 ± 1.0‰ (1σ). Calcite precipitated soon afterwards, and following a fall in solution Mg/Ca ratios, to produce small equant grains with a mean oxygen isotope value of δ18O 37.5 ± 0.7‰, Δ17O 1.4 ± 1.1‰ (1σ). These grains were partially or completely replaced by serpentine and tochilinite prior to precipitation of the second generation of calcite, which occluded an open fracture to form a millimetre-sized vein, and replaced anhydrous silicates within chondrules and the matrix. The vein calcite has a mean composition of δ18O 18.4 ± 0.3‰, Δ17O -0.5 ± 0.5‰ (1σ). Petrographic and isotopic results therefore reveal two discrete episodes of mineralisation that produced calcite generations with contrasting δ18O, and mean Δ17O values. The aragonite and equant calcite crystallized over a relatively brief period early in the aqueous alteration history of the parent body, and from static fluids that were evolving chemically in response to mineral dissolution and precipitation. The second calcite generation crystallized from solutions of a lower Δ17O, and a lower δ18O and/or higher temperature. As two generations of calcite whose petrographic characteristics and oxygen isotopic compositions are similar to those in LON 94101 occur in at least one other CM2, multiphase carbonate mineralisation could be the typical outcome of the sequence of chemical reactions during parent body aqueous alteration. It is equally possible however that the second generation of calcite formed in response to an event such as impact fracturing and concomitant fluid mobilisation that affected

  7. Water Transport and the Evolution of CM Parent Bodies

    NASA Technical Reports Server (NTRS)

    Coker, Rob; Cohen, Barbara

    2014-01-01

    Meteorites have amino acids and hydrated minerals which constrain the peak temperature ranges they have experienced. CMs in particular have a narrow range (273-325K). Bulk fluid motion during hydration constrained to small scales (less than mm). Some asteroids are known to have hydrated minerals on their surfaces. It is presumed these two facts may be related. Problem: hydration only occurs (significantly) with liquid water; melting water only occurs early on in nebula (1-10 Myrs ANC); in nebula asteroid surface temperature very cold (approximately 150K). Can indigenous alteration produce CMs and/or surface hydration?

  8. Workshop on Meteorites From Cold and Hot Deserts

    NASA Technical Reports Server (NTRS)

    Schultz, Ludolf (Editor); Annexstad, John O. (Editor); Zolensky, Michael E. (Editor)

    1994-01-01

    The current workshop was organized to address the following points: (1) definition of differences between meteorites from Antarctica, hot deserts, and modern falls; (2) discussion of the causes of these differences; (3) implications of possible different parent populations, infall rates, weathering processes, etc.; (4) collection, curation, and distribution of meteorites; and (5) planning and coordination of future meteorite searches.

  9. Mineralogy and Ar-39 - Ar-40 of an old pristine basalt: Thermal history of the HED parent body

    NASA Technical Reports Server (NTRS)

    Takeda, Hiroshi; Mori, Hiroshi; Bogard, Donald D.

    1994-01-01

    Previous investigations of mineral chemistry and Rb-Sr and Sm-Nd ages indicated that clast,84 from eucrite Yamato 75011 had preserved the pristine nature of its initial crystallization during an early stage of the HED parent body. Microscale mineralogy and Ar-39-Ar-40 ages of this clast, however, revealed local disturbance of microtextures and partially reset ages. This evidence suggests that, in addition to initial crystallization and rapid cooling, the Y75011,84 clast experienced shock deformation, reheating of short duration at higher temperature, and brecciation. These characteristics suggest two or more impact events. Fe-rich olivine filling fractures in pyroxene may have been introduced during the accompanying shock fracturing. The inferred Ar-39-Ar-40 degassing ages for Y75011 matrix and clast, 84 are 3.94 +/- 0.04 Ga and 3.98 +/- 0.03 Ga, respectively. The suggested degassing age for a clast from Y790020, believed to be paired with Y75011, is approximately 4.03 Ga, but could be younger. We consider it likely that all three samples experienced a common degassing event 3.95 +/- 0.05 Ga ago, but we cannot rule out two or more events spaced over a approximately 0.1 Ga interval. Higher temperature extractions of the two clast samples show significantly older apparent ages up to approximately 4.5 Ga and suggest that the time/temperature regime of this event was not sufficient to degas Ar totally. Most likely, the K-Ar ages were reset by thermal metamorphism associated with one or more impact events associated with shock fracturing, formation of Fe-rich olivine veins, and/or meteorite brecciation. The pyroxene annealing that commonly occurs in many eucrites is likely to be a much earlier process than the impact-produced textural changes and reset K-Ar ages observed in these meteorites. The existence of mineralogical and chronological evidence for metamorphism in an otherwise pristine eucrite suggests that the HED parent body experienced an extensive degree of

  10. A Single Lodranite/Acapulcoite Parent Body: Noble Gases in Lodranite QUE 93148 and Acapulcoite ALH 81261

    NASA Astrophysics Data System (ADS)

    Weigel, A.; Eugster, O.; Marti, K.; Michel, R.

    1995-09-01

    We continue our comprehensive studies of the cosmic ray exposure history of lodranites [1] to include new noble gas measurements in the QUE 93148 lodranite and the ALH 81261 acapulcoite. In addition, we model the production rates of cosmogenic nuclides in lodranites and acapulcoites using the HERMES high energy transport code [2], in order to test whether conventional production rates can be extrapolated to this group of small meteoroids which reveal very large values of the shielding parameter 22Ne/21Ne (Table 1). The model calculations are based on the same excitation functions of p- and n-induced reactions as used in recent calculations [3,4]. We extended our studies to acapulcoites, since petrologic, mineralogic, and O-isotopic investigations [5] as well as chemical investigations [6] suggest that lodranites and acapulcoites are residues of varying degree of partial melting, consistent with an origin on a common parent body. Whether a collisional event on the common parent body ejected both types of meteorites can be investigated by an analysis of the transfer times to Earth, specifically their cosmic-ray exposure ages. Because the contents of trapped He, Ne, and Ar in lodranites and acapulcoites are very low we can derive reliable cosmogenic noble gas contents. Using the composition-adjusted production rates for cosmogenic noble gases in achondrites [7], and adopting the shielding-parameter dependence for H-chondrites the exposure ages of [1] are obtained. For lodranites these exposure ages overlap those calculated [8] from 26Al and 10Be measurements. For the acapulcoites our exposure ages agree with those [5] calculated with the Graf-model [9], as well as with the shielding-independent exposure age for Acapulco that is based on the 36Cl-36Ar method[10]. The large spread in the exposure ages can be attributed to the highly variable target element abundances, as multiple measurements on several aliquots show unusually large variations. The fact that the average

  11. The meteoritic record of presolar and early solar system organic chemistry. [Abstract only

    NASA Technical Reports Server (NTRS)

    Cronin, John R.; Pizzarello, Sandra

    1994-01-01

    Carbon, hydrogen, and nitrogen isotopic analyses of various classes of organic compounds done in collaboration with Epstein and Krishnamurthy (Caltech) have shown these compounds to be enriched to varying degrees in the heavier isotopes. These results, in particular the large deuterium enrichments, have been interpreted as indicating an interstellar origin for the meteorite compounds or their precursors. Such isotopic fractionations, of hydrogen especially, are characteristic of low temperature ion-molecule reactions in cold interstellar clouds. There is also evidence from the large corresponding suites of alpha-amino and alpha-hydroxy acids found in meteorites suggesting that aqueous phase chemistry on the meteorite parent body played an important role in the formation of these compounds. These data support the hypothesis that interstellar compounds survived in the solar nebula at a radial distance corresponding to the asteroid belt, were incorporated into the parent body in icy, volatile-rich, planetesinals, and underwent further reactions during a period of aqueous activity within the early parent body to give the present suite of meteorite compounds. This formation hypothesis will be discussed and the results of recent isotopic and molecular analyses bearing on it will be presented.

  12. Nature's Starships: Amino Acid Synthesis, Frequency, and Delivery to Earth via Meteorites

    NASA Astrophysics Data System (ADS)

    Cobb, Alyssa; Pudritz, Ralph

    2013-07-01

    Understanding the origin of organic molecules on Earth is vital to our understanding of the origins of life. One proposed mechanism for the introduction of organic material to our planet is via meteorite impacts. Meteoritic parent bodies contain organic material and water ice, which, given radionuclide decay in their interiors, cause the ice to melt and the parent bodies to undergo a process called aqueous alteration. An example of this internal chemistry is Strecker synthesis, a process resulting in the production of various amino acids. Our work summarizes recent discoveries regarding amino acid synthesis and concentration data. We present the amino acid concentrations collated from a variety of meteorites (~20) covering a range of meteorite classes. We can use the dependence of amino acid frequency on variables such as temperature and pressure to model Strecker synthesis inside a theoretical parent body. Our modeling software takes a set of chemical species and outputs their relative frequencies based on a minimization of their Gibbs free energies. The goal of this work is to predict and quantify the presence of amino acids on a foreign landscape using thermodynamic principles.

  13. The Chelyabinsk meteorite fall: Geochemistry and Mineralogy

    NASA Astrophysics Data System (ADS)

    Galimov, Eric

    suggestthat the Chelyabinsk meteorite parent body was affected by a major impact event at approximately 290 Ma; however, this event did not completely homogenize its Nd isotope composition. The Sr isotopic system was also not homogenized by this event. VH nuclei tracks of solar cosmic rays were detected in the meteorite; this indicates that a part of collected material could occur on the surface of the parent body. The results of the research were published in special issue of the Geochemistry journal (N6, 2013). The meteorite name was approved by the Meteoritical Society.

  14. Hotter, Faster: A Thermal Model for the H-Chondrite Parent Body Consistent with Chronology and Cooling Rates

    NASA Astrophysics Data System (ADS)

    McSween, H. Y., Jr.; Bennett, M. E., III

    1995-09-01

    HOTTER, FASTER: A THERMAL MODEL FOR THE H-CHONDRITE PARENT BODY CONSISTENT WITH CHRONOLOGY AND COOLING RATES. H. Y. McSween, Jr. and M. E. Bennett, III, Department of Geological Sciences, University of Tennessee, Knoxville, TN 37996, USA. Because of the abundant sampling and relatively low shock levels of H chondrites, their thermal histories are more tightly constrained than for other ordinary chondrites; consequently, rigorous models for the thermal evolution of their parent asteroid can be formulated that are not possible for other chondrite groups. A revised thermal model for the H-chondrite parent asteroid [Bennett and McSween], based on heating by decay of 26Al, follows the formulation of [Miyamoto and Fujii] except: the unfounded constraint that the relative volumes of different petrologic types must mimic meteorite fall statistics is removed, a shortened thermal history of 60 Ma [Gopel et al] rather than 100 Ma is adopted, and improved geothermometry constraints and measurements of thermal properties [Yomogida and Matsui] are used. Our new model predicts a parent body of approximately 88 kilometers radius, containing a much larger volumetric proportion (71%) of H6 material than in the previous model, with a high thermal gradient and correspondingly small proportions of H5 and H4 material (together comprising 10%) near the surface. Constraints on chronology and cooling rates from H chondrites are used as independent tests of the model. 26Al heating requires that the body accreted 1.5-3.1 Ma after formation of CAIs to reach the measured peak temperature for H6 chondrites, consistent with the 3.0 + 2.6 Ma estimate from Pb/Pb chronology [Gopel et al]. Times of Pb isotopic closure, relative to CAIs, in H-chondrite phosphates (3-5 Ma for H4, 10-16 Ma for H5, 42-62 Ma for H6, from [Gopel et al]) precisely overlap the thermal model estimates. In particular, the markedly shorter duration of heating for H4-5 chondrites agrees with model predictions. The model also

  15. Parents' and boys' perceptions of boys' body size for average and high BMI boys.

    PubMed

    Brann, Lynn S

    2011-07-01

    A study on 49 preadolescent boys and their parents was performed to determine if differences existed in boys' body esteem and body size perceptions and to determine how accurately parents perceive their sons' body size. The boys were grouped by their body mass index (BMI) into average and high BMI groups. The boys completed the Body Esteem Scale; the boys and the parents rated the boys' body size perceptions. No differences were found in the boys' body esteem. The boys in the high BMI group perceived themselves as bigger than the boys in the average BMI group, and the parents of the boys with a high BMI perceived their sons as bigger. The boys in the high BMI group rated their current figure as heavier than their ideal figure. The results supported that the boys and the parents were aware of the boys' current body size. However, the parents of the boys with high BMI were more accepting of a larger ideal body figure. PMID:21689273

  16. Explosive volcanism and the graphite-oxygen fugacity buffer on the parent asteroid(s) of the ureilite meteorites

    NASA Technical Reports Server (NTRS)

    Warren, Paul H.; Kallemeyn, Gregory W.

    1992-01-01

    A new model of the production of the uniformly low plagioclase and Al contents of ureilites is proposed. It is argued that those contents are consequences of widespread explosive volcanism during the evolution of the parent asteroid(s). It is noted that the great abundance of graphite on the ureilite asteroid(s) made them ideal sites for explosive volcanism driven by oxidation of graphite in partial melts ascending within the asteroid(s).

  17. Experimental Simulation of Shock Reequilibration of Fluid Inclusions During Meteorite Impact

    NASA Technical Reports Server (NTRS)

    Madden, M. E. Elwood; Hoerz, R. J.; Bodnar, R. J.

    2003-01-01

    Fluid inclusions are microscopic volumes of fluid trapped within minerals as they precipitate. Fluid inclusions are common in terrestrial minerals formed under a wide array of geological settings from surface evaporite deposits to kimberlite pipes. While fluid inclusions in terrestrial rocks are the rule rather than the exception, only few fluid inclusion-bearing meteorites have been documented. The rarity of fluid inclusions in meteoritic material may be explained in two ways. First, it may reflect the absence of fluids (water?) on meteorite parent bodies. Alternatively, fluids may have been present when the rock formed, but any fluid inclusions originally trapped on the parent body were destroyed by the extreme P-T conditions meteorites often experience during impact events. Distinguishing between these two possibilities can provide significant constraints on the likelihood of life on the parent body. Just as textures, structures, and compositions of mineral phases can be significantly altered by shock metamorphism upon hypervelocity impact, fluid inclusions contained within component minerals may be altered or destroyed due to the high pressures, temperatures, and strain rates associated with impact events. Reequilibration may occur when external pressure-temperature conditions differ significantly from internal fluid isochoric conditions, and result in changes in fluid inclusion properties and/or textures. Shock metamorphism and fluid inclusion reequilibration can affect both the impacted target material and the meteoritic projectile. By examining the effects of shock deformation on fluid inclusion properties and textures we may be able to better constrain the pressure-temperature path experienced by shocked materials and also gain a clearer understanding of why fluid inclusions are rarely found in meteoritic samples.

  18. Parenting styles, feeding styles, and their influence on child obesogenic behaviors and body weight. A review.

    PubMed

    Vollmer, Rachel L; Mobley, Amy R

    2013-12-01

    With recommendations to include parents as targets for childhood obesity interventions, there is a need to review the relationship of general parenting influences on childhood obesity. Therefore, the aim of this review is to examine the existing literature regarding the influence of parenting style and/or feeding styles on childhood obesogenic behaviors and body weight. Research articles related to parenting style (n=40) and parental feeding style (n=11) were identified and reviewed. An authoritative style appears to be the most protective parenting and feeding style while the indulgent feeding style is consistently associated with negative health outcomes. Overall, results for parenting style studies are inconsistent due to differences in conceptualization and measurement, while the results for feeding styles are much more cohesive. The literature is lacking in the ability to describe the interplay between parenting and feeding styles and child obesity risk. Recommendations for future research and interventions are discussed in regards to feeding style and influences on childhood obesity.

  19. Carboxylic Acids as Indicators of Parent Body Conditions

    NASA Technical Reports Server (NTRS)

    Lerner N. R.; Chang, Sherwood (Technical Monitor)

    1995-01-01

    Alpha-hydroxy and alpha-amino carboxylic acids found on the Murchison meteorite are deuterium enriched. It is postulated that they arose from a common interstellar scurce: the reaction of carbonyl compounds in an aqueous mixture containing HCN and NH3. Carbonyl compounds react with HCN to form alpha-hydroxy nitriles, RR'CO + HCN right and left arrow RR'C(OH)CN. If ammonia is also present, the alpha-hydroxy nitriles will exist in equilibrium with the alpha-amino nitriles, RR'C(OH)CN + NH3 right and left arrow - RRCNH2CN + H2O. Both nitrites are hydrolyzed by water to form carboxylic acids: RR'C(OH)CN + H2O yields RR'C(OH)CO2H and RR'C(NH2)CN + H2O yields RR'C(NH2)CO2H.

  20. Mineralogical Study of Reddish Olivine in Dhofar 307 Lunar Meteorite: Comparison with Brown Olivine in Martian Meteorites

    NASA Astrophysics Data System (ADS)

    Takenouchi, A.; Mikouchi, T.

    2016-08-01

    We compared reddish olivine in Dhofar 307 lunar meteorite to brown olivine in martian meteorites and indicate a possibility of its shock origin. This result suggests that olivine darkening may have widely occurred on the surface of large bodies.

  1. 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.

  2. Reflectance spectra of mafic silicate-opaque assemblages with applications to meteorite spectra

    NASA Technical Reports Server (NTRS)

    Cloutis, Edward A.; Smith, Dorian G. W.; Lambert, Richard St. J.; Gaffey, Michael J.

    1990-01-01

    The addition of fine-grained magnetite to mafic silicate spectra can impart not only an overall blue slope, but also lower overall reflectance and band intensities. The reflectance spectra of the CO and CV magnetite-bearing carbonaceous chondrites are noted to exhibit many of these features; the low band depths of these meteorites suggest that an additional dark, neutral phase, such as ordered carbon, is present. Carbon + mafic silicate spectra possess a red overall slope at low amorphous carbon concentrations. The parent bodies of some of the darkest meteorites should exhibit spectral features attributable to mafic silicates.

  3. Aqueous alteration of the Nakhla meteorite

    SciTech Connect

    Gooding, J.L.; Zolensky, M.E.; Wentworth, S.J. Lockheed Engineering and Sciences Co., Houston, TX )

    1991-06-01

    Interior samples of three different Nakhla specimens contain an iron-rich silicate 'rust' (which includes a tentatively identified smectite), Ca-carbonate (probably calcite), Ca-sulfate (possibly gypsum or bassanite), Mg-sulfate (possibly epsomite or kieserite), and NaCl (halite); the total abundance of these phases is estimated as less than 0.01 weight percent of the bulk meteorite. Rust veins are truncated and decrepitated by fusion crust and are preserved as faulted segments in partially healed olivine crystals, indicating that the rust is preterrestrial in origin. Because Ca-carbonate and Ca-sulfate are intergrown with the rust, they are also indicated to be of preterrestrial origin. Similar textural evidence regarding origins of the NaCl and Mg-sulfate is lacking. Impure and poorly crystallized sulfates and halides on the fusion crust of the meteorite suggest leaching of interior (preterrestrial) salts from the interior after Makhla arrived on earth, but coincidental addition of these same salts by terrestrial contamination cannot be exluded. At least the clay-like silicate 'rust', Ca-carbonate, and Ca-sulfate were formed by precipitation from water-based solutions on the Nakhla parent planet, although temperature and pressure conditions of aqueous precipitation are unconstrained by currently available data. It is possible that aqueous alteration on the parent body was responsible for the previously observed disturbance of the Rb-Sr geochronometer in Nakhla at or near 1.3 Ga. 21 refs.

  4. Parental Misperception of Their Child's Body Weight Status Impedes the Assessment of the Child's Lifestyle Behaviors.

    PubMed

    Mathieu, Marie-Eve; Drapeau, Vicky; Tremblay, Angelo

    2010-01-01

    Objectives. To examine if distinct characteristics are associated with parental misclassification of underweight (UW), normal weight (NW), and overweight or obese (OWOB) children and the implications of misclassification on the parental evaluation of the child's lifestyle habits. Methods. Cross-sectional analysis (2004 sample) of the Quebec Longitudinal Study of Child Development (1998-2010) (n = 1,125). Results. 16%, 55%, and 77% of NW, UW and OWOB children were perceived inaccurately, respectively. Misperception was significantly higher in nonimmigrant parents of UW children, in highly educated parents of NW children and in NW and OWOB children with lower BMI percentiles. Erroneous body weight status identification impedes the evaluation of eating habits of all children as well as physical activity and fitness levels of UW and OWOB children. Conclusion. Parental misclassification of the child's body weight status and lifestyle habits constitutes an unfavorable context for healthy body weight management.

  5. Correlates of parental feeding practices with pre-schoolers: Parental body image and eating knowledge, attitudes, and behaviours.

    PubMed

    Damiano, Stephanie R; Hart, Laura M; Paxton, Susan J

    2016-06-01

    Parental feeding practices have been linked to eating and weight status in young children; however, more research is needed to understand what influences these feeding practices. The aim of this study was to examine how parental feeding practices that are linked to unhealthy eating patterns in young children, are related to parental body image and eating knowledge, attitudes, and behaviours . Participants were 330 mothers of a 2- to 6-year-old child. Mothers completed measures of knowledge of child body image and eating patterns, overvaluation of weight and shape, internalization of general media and athletic ideals, dieting, and parental feeding practices. Higher maternal knowledge of strategies to promote positive child body image and eating patterns predicted lower weight restriction, instrumental, emotional, and pushing to eat feeding practices. Overvaluation of weight and shape predicted use of fat restriction. Maternal internalization of the athletic ideal predicted instrumental and pushing to eat feeding practices. As these feeding practices have been associated with long-term risk of children's weight gain and/or disordered eating, these findings highlight the need for prevention interventions to target knowledge, attitudes, and behaviours of parents of pre-schoolers. PMID:26952561

  6. Correlates of parental feeding practices with pre-schoolers: Parental body image and eating knowledge, attitudes, and behaviours.

    PubMed

    Damiano, Stephanie R; Hart, Laura M; Paxton, Susan J

    2016-06-01

    Parental feeding practices have been linked to eating and weight status in young children; however, more research is needed to understand what influences these feeding practices. The aim of this study was to examine how parental feeding practices that are linked to unhealthy eating patterns in young children, are related to parental body image and eating knowledge, attitudes, and behaviours . Participants were 330 mothers of a 2- to 6-year-old child. Mothers completed measures of knowledge of child body image and eating patterns, overvaluation of weight and shape, internalization of general media and athletic ideals, dieting, and parental feeding practices. Higher maternal knowledge of strategies to promote positive child body image and eating patterns predicted lower weight restriction, instrumental, emotional, and pushing to eat feeding practices. Overvaluation of weight and shape predicted use of fat restriction. Maternal internalization of the athletic ideal predicted instrumental and pushing to eat feeding practices. As these feeding practices have been associated with long-term risk of children's weight gain and/or disordered eating, these findings highlight the need for prevention interventions to target knowledge, attitudes, and behaviours of parents of pre-schoolers.

  7. Impact Crater Particulates: Microscopic Meteoritic Material Surrounding Meteorite Craters

    NASA Astrophysics Data System (ADS)

    Smith, Toby Russell

    1995-01-01

    The influx of extraterrestrial matter onto the Earth is a ongoing process. Every year 40,000 metric tons of extraterrestrial matter is accreted by the Earth (Love 1993). A small fraction of this material arrives at Earth as objects large enough to survive the passage through atmosphere. Some of this material is completely melted as it passes through the atmosphere and arrives at the surface of the Earth as cosmic spherules. Cosmic spherules formed from metallic cosmic material undergoes changes in its elemental abundance as it passes through the atmosphere. The oxidation of the spherules results in the concentration of more refractory elements like Ni and Co into the metallic phase. Cosmic spherules are also formed by the passage of large meteorites through the atmosphere and their resulting impact onto the Earth. I found that the cosmic spherules from a wide variety of sources show a very similar trend in the elemental abundance patterns of their metallic phases. This trend is most obvious in the spherules recovered from the deep -sea and the spherules imbedded in impactite glass recovered from iron meteorite impact crater sites. The metallic spherules recovered from the soil surrounding impact craters do not show the high degree of elemental fractionation found in the deep-sea and impactite spherules. The composition of these spherules indicate that they are a mixture of meteoritic and target material. Metallic spherules are not the only meteoritic material to be found in the soil surrounding meteorite craters. I found that small fragments of the parent meteorite are an ubiquitous component of the soil surrounding the Odessa and Dalgaranga meteorite craters. These fragments occurred as small (most less than 400 mu m in size) heavily weathered fragments of meteoritic metal. The total calculated mass of these fragments is an order of magnitude larger than the mass of ponderable meteorites recovered from the site but 1 to 2 orders of magnitude smaller than the

  8. Cation ordering in orthopyroxenes and cooling rates of meteorites: Low temperature cooling rates of Estherville, Bondoc and Shaw

    NASA Technical Reports Server (NTRS)

    Ganguly, J.; Yang, H.; Ghose, S.

    1993-01-01

    The cooling rates of meteorites provide important constraints on the size of their parent bodies, and their accretionary and evolutionary histories. However, the cooling rates obtained so far from the commonly used metallographic, radiometric and fission-track methods have been sometimes quite controversial, such as in the case of the mesosiderites and the meteorite Shaw. We have undertaken a systematic study of the cooling rates of meteorites using a different approach, which involves single crystal x-ray determination of Fe(2+)-Mg ordering in orthopyroxenes (OP(x)) in meteorites, subject to bulk compositional constraints, and numerical simulation of the evolution of the ordering state as a function of cooling rate, within the framework of the thermodynamic and kinetic principles governing cation ordering. We report the results obtained for OP(x) crystals from Shaw and two mesosiderites, Estherville and Bondoc.

  9. Melt inclusions in augite from the nakhlite meteorites: A reassessment of nakhlite parental melt and implications for petrogenesis

    NASA Astrophysics Data System (ADS)

    Sautter, Violaine; Toplis, Michael J.; Lorand, Jean-Pierre; Macri, Michele

    2012-03-01

    The nakhlites, a subgroup of eight clinopyroxenites thought to come from a single geological unit at the Martian surface, show melt inclusions in augite and olivine. In contrast to olivine-hosted melt inclusions, augite-hosted melt inclusions are not surrounded by fractures, and are thus considered preferential candidates for reconstructing parent liquid compositions. Furthermore, two types of augite-hosted melt inclusion have been defined and characterized in four different nakhlites (Northwest Africa [NWA] 817, Nakhla, Governador Valadares, and NWA 998): Type-I isolated inclusions in augite cores that contain euhedral to subhedral augite, Ti-magnetite, and pigeonite plus silica-rich glass and a gas bubble; Type-II microinclusions that form trails crosscutting host augite crystals. Fast-heating experiments were performed on selected pristine primary augite-hosted melt inclusions from these four samples. Of these, only data from Nakhla were considered robust for reconstruction of a nakhlite parental magma composition (NPM). Based upon careful petrographic selection and consideration of iron-magnesium ratios, our data are used to propose an NPM, which is basaltic (49.1 wt% SiO2), of high Ca/Al (1.95), and K2O-poor (0.32 wt%). Thermodynamic modeling at an oxygen fugacity one log unit below the QFM buffer using the MELTS and PETROLOG programs implies that Mg-rich olivine was not a liquidus phase for this composition. Our analysis is used to suggest that olivine megacrysts found in the nakhlites are unlikely to have coprecipitated with augite, and thus may have been introduced during or subsequent to accumulation in the magma chamber, possibly from more evolved portions of the same chamber.

  10. Extraterrestrial Amino Acids in the Almahata Sitta Meteorite

    NASA Technical Reports Server (NTRS)

    Glavin, Daniel P.; Aubrey, Andrew D.; Callahan, Michael P.; Dworkin, Jason P.; Elsila, Jamie E.; Parker, Eric T.; Bada, Jeffrey L.

    2010-01-01

    Amino acid analysis of a meteorite fragment of asteroid 2008 TC3 called Almahata Sitta was carried out using reverse-phase liquid chromatography coupled with UV fluorescence detection and time-of-flight mass spectrometry (LC-FD/ToF-MS) as part of a sample analysis consortium. LC-FD/ToF-MS analyses of hot-water extracts from the meteorite revealed a complex distribution of two- to seven-carbon aliphatic amino acids and one- to three-carbon amines with abundances ranging from 0.5 to 149 parts-per-billion (ppb). The enantiomeric ratios of the amino acids alanine, R-amino-n-butyric acid (beta-ABA), 2-amino-2-methylbutanoic acid (isovaline), and 2-aminopentanoic acid (norvaline) in the meteorite were racemic (D/L approximately 1), indicating that these amino acids are indigenous to the meteorite and not terrestrial contaminants. Several other non-protein amino acids were also identified in the meteorite above background levels including alpha-aminoisobutyric acid (alpha-AIB), 4-amino-2- methylbutanoic acid, 4-amino-3-methylbutanoic acid, and 3-, 4-, and 5-aminopentanoic acid. The total abundances of isovaline and alpha-AIB in Almahata Sitta are 1000 times lower than the abundances of these amino acids found in the CM carbonaceous chondrite Murchison. The extremely low abundances and unusual distribution of five carbon amino acids in Almahata Sitta compared to Cl, CM, and CR carbonaceous chondrites may reflect extensive thermal alteration of amino acids on the parent asteroid by partial melting during formation or subsequent impact shock heating. It is also possible that amino acids were synthesized by catalytic reactions on the parent body after asteroid 2008 TC3 cooled to lower temperatures.

  11. Mineralogy of Meteorite Groups

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.

    1997-01-01

    phases were formed by shock metamorphism. Martensite (a2-fe,Ni) has a distorted body-centered-cubic structure and formed by a shear transformation from taenite during shock reheating and rapid cooling. The C polymorphs diamond, lonsdaleite and chaoite formed by shock from graphite. Suessite formed in the North Haig ureilite by reduction of Fe and Si (possibly from olivine) via reaction with carbonaceous matrix material. Ringwoodite, the spinel form of (Mg,Fe)2Si04, and majorite, a polymorph of (Mg,Fe)Si03 with the garnet structure, formed inside shock veins in highly shocked ordinary chondrites. Secondary minerals in meteorite finds that formed during terrestrial weathering include oxides and hy-. droxides formed directly from metallic Fe-Ni by oxidation, phosphates formed by the alteration of schreibersite, and sulfates formed by alteration of troilite.

  12. A Comparison of Metallographic Cooling Rate Methods Used in Meteorites

    NASA Technical Reports Server (NTRS)

    Herpfer, Marc A.; Larimer, John W.; Goldstein, J. I.

    1994-01-01

    The primary objective of this study was to test the postulate that cooling rates acquired from metal grains in chondrites are consistent with those from iron meteorites. Both types of metal occur in some Group IAB meteorites, which are mixtures of massive metal with well-developed Widmanstatten structures and chondritic inclusions with dispersed metal grains. The grains have textures and compositions similar to chondritic metal, including negligible P. The meteorites studied show little or no sign of shock reheating and textural evidence indicates that silicates and metal were mixed before Widmanstatten patterns formed during cooling. Cooling rates were obtained by comparing measured to modeled taenite grain or lamellae dimensions and central Ni contents. Modeling entails solving diffusion equations using experimental diffusion coefficients, phase relations, and bulk or local Ni and P contents, taking into account geometry, undercooling, and impingement. There is one set of parameters for grains and another, quite different set for Widmanstatten lamellae, including a factor of 30 difference in diffusion coefficients. Yet cooling rates obtained from Widmanstatten structures and metal grains in chondritic inclusions of the same meteorite are consistent; uncertainties in the best data are +/- 10 K/Ma, equivalent to a factor of 1 +/- 0.25. This agreement implies that the data and models are correct or contain fortuitously offsetting errors, which is quite unlikely. Cooling rates range from 40 K/Ma to 70 K/Ma in IAB meteorites that contain both grains and Widmanstatten structures. Rates based on grains in Ni-poor and Ni-rich meteorites lacking Widmansatten patterns expand the range from 30 K/Ma to perhaps 200 K/Ma. Cooling rates correlate with Ni content; Ni-poor meteorites have slower rates than Ni-rich ones. Evidently, IAB meteorites were radially distributed over greater than 30km in a body with a radius less than 50km. A comparison of the available Ar ages with

  13. Bodies as evidence: Mapping new terrain for teen pregnancy and parenting.

    PubMed

    Gubrium, Aline C; Fiddian-Green, Alice; Jernigan, Kasey; Krause, Elizabeth L

    2016-01-01

    Predominant approaches to teen pregnancy focus on decreasing numbers of teen mothers, babies born to them, and state dollars spent to support their families. This overshadows the structural violence interwoven into daily existence for these young parents. This paper argues for the increased use of participatory visual methods to compliment traditional research methods in shifting notions of what counts as evidence in response to teen pregnancy and parenting. We present the methods and results from a body mapping workshop as part of 'Hear Our Stories: Diasporic Youth for Sexual Rights and Justice', a project that examines structural barriers faced by young parenting Latinas and seeks to develop relevant messaging and programming to support and engage youth. Body mapping, as an engaging, innovative participatory visual methodology, involves young parenting women and other marginalised populations in drawing out a deeper understanding of sexual health inequities. Our findings highlight the ways body mapping elicits bodies as evidence to understand young motherhood and wellbeing.

  14. Bodies as evidence: Mapping new terrain for teen pregnancy and parenting.

    PubMed

    Gubrium, Aline C; Fiddian-Green, Alice; Jernigan, Kasey; Krause, Elizabeth L

    2016-01-01

    Predominant approaches to teen pregnancy focus on decreasing numbers of teen mothers, babies born to them, and state dollars spent to support their families. This overshadows the structural violence interwoven into daily existence for these young parents. This paper argues for the increased use of participatory visual methods to compliment traditional research methods in shifting notions of what counts as evidence in response to teen pregnancy and parenting. We present the methods and results from a body mapping workshop as part of 'Hear Our Stories: Diasporic Youth for Sexual Rights and Justice', a project that examines structural barriers faced by young parenting Latinas and seeks to develop relevant messaging and programming to support and engage youth. Body mapping, as an engaging, innovative participatory visual methodology, involves young parenting women and other marginalised populations in drawing out a deeper understanding of sexual health inequities. Our findings highlight the ways body mapping elicits bodies as evidence to understand young motherhood and wellbeing. PMID:26895231

  15. Neodymium Isotopes in Ordinary Chondrites and the Role of Metamorphism on the Parent Body

    NASA Astrophysics Data System (ADS)

    Armytage, R. M. G.; Debaille, V.

    2016-08-01

    Ordinary chondrites have been proposed as a chondritic isotopic reference value for Earth. We present Nd isotopic data for a suite of ordinary chondrites to investigate the effect of parent body processes on isotopic variability.

  16. Child Disinhibition, Parent Restriction, and Child Body Mass Index in Low-Income Preschool Families

    ERIC Educational Resources Information Center

    Sparks, Martha A.; Radnitz, Cynthia L.

    2013-01-01

    Objective: To examine both unique and interactive effects of parent restrictive feeding and child disinhibited eating behavior on child body mass index (BMI) in low-income Latino and African American preschoolers. Methods: The sample included 229 parent-child pairs, the majority of whom were low-income and Latino (57%) or African American (25%).…

  17. Parent/Student Risk and Protective Factors in Understanding Early Adolescent's Body Mass Index

    ERIC Educational Resources Information Center

    Fitzpatrick, Kevin M.; Willis, Don

    2016-01-01

    This article's aim is to examine correlates of middle school students' body mass index (BMI). Little research simultaneously has considered both child and parent correlates in predicting child's BMI; we examine the interrelationships between middle school students and their parent's risks and protective factors and their impact on the child's BMI.…

  18. The Orgueil meteorite: 150 years of history

    NASA Astrophysics Data System (ADS)

    Gounelle, Matthieu; Zolensky, Michael E.

    2014-10-01

    The goal of this paper is to summarize 150 yr of history of a very special meteorite. The Orgueil meteorite fell near Montauban in southwestern France on May 14, 1864. The bolide, which was the size of the full Moon, was seen across Western France, and almost immediately made the news in local and Parisian newspapers. Within a few weeks of the fall, a great diversity of analyses were performed under the authority of Gabriel Auguste Daubrée, geology professor at the Paris Museum, and published in the Comptes Rendus de l'Académie des Sciences. The skilled scientists reported the presence of iron sulfides, hydrated silicates, and carbonates in Orgueil. They also characterized ammonium salts which are now gone, and observed sulfates being remobilized at the surface of the stone. They identified the high water and carbon contents, and noted similarities with the Alais meteorite, which had fallen in 1806, 300 km away. While Daubrée and his colleagues noted the similarity of the Orgueil organic matter with some terrestrial humus, they were cautious not to make a direct link with living organisms. One century later, Nagy and Claus were less prudent and announced the discovery of "organized" elements in some samples of Orgueil. Their observations were quickly discredited by Edward Anders and others who also discovered that some pollen grains were intentionally placed into the rock back in the 1860s. Orgueil is now one of the most studied meteorites, indeed one of the most studied rocks of any kind. Not only does it contain a large diversity of carbon-rich compounds, which help address the question of organo-synthesis in the early solar system but its chemical composition is also close to that of the Sun's photosphere and serves as a cosmic reference. Secondary minerals, which make up 99% of the volume of Orgueil, were probably formed during hydrothermal alteration on the parent-body within the first few million years of the solar system; their study is essential to our

  19. On the likely parent body of the χ-Orionid meteoroid stream

    NASA Astrophysics Data System (ADS)

    Madiedo, J. M.; Ortiz, J. L.; Cabrera, J.; Trigo-Rodriguez, J. M.; Toscano, F. M.

    2012-09-01

    One of the aims of the SPanish Meteor Network (SPMN) is the monitoring of the activity of minor meteor showers and the analysis of the potential parent bodies of the corresponding meteoroids. For this purpose we employ, among other devices, highsensitivity CCD video cameras with attached holographic diffraction gratings. In this context, we analyze here the emission spectrum, trajectory, orbital parameters and potential parent body of a Northern χ-Orionid bolide imaged in 2011.

  20. A Propensity for n-omega-Amino Acids in Thermally-Altered Antarctic Meteorites

    NASA Technical Reports Server (NTRS)

    Burton, Aaron S.; Elsila, Jamie E.; Callahan, Michael P.; Martin, Mildred G.; Glavin, Daniel P.; Johnson, Natasha M.; Dworkin, Jason P.

    2012-01-01

    Carbonaceous meteorites are known to contain a wealth of indigenous organic molecules, including amino acids, which suggests that these meteorites could have been an important source of prebiotic organic material during the origins of life on Earth and possibly elsewhere. We report the detection of extraterrestrial amino acids in thermally-altered type 3 CV and CO carbonaceous chondrites and ureilites recovered from Antarctica. The amino acid concentrations of the thirteen Antarctic meteorites were generally less abundant than in more amino acid-rich CI, CM, and CR carbonaceous chondrites that experienced much lower temperature aqueous alteration on their parent bodies. In contrast to low-temperature aqueously-altered meteorites that show complete structural diversity in amino acids formed predominantly by Strecker-cyanohydrin synthesis, the thermally-altered meteorites studied here are dominated by small, straight-chain, amine terminal (n-omega-amino) amino acids that are not consistent with Strecker formation. The carbon isotopic ratios of two extraterrestrial n-omega-amino acids measured in one of the CV chondrites are consistent with C-13-depletions observed previously in hydrocarbons produced by Fischer-Tropsch type reactions. The predominance of n-omega-amino acid isomers in thermally-altered meteorites hints at cosmochemical mechanisms for the preferential formation and preservation of a small subset of the possible amino acids.

  1. Shock Modifications of Organic Compounds in Carbonaceous Chondrite Parent Bodies

    NASA Technical Reports Server (NTRS)

    Cooper, George W.

    1998-01-01

    Impacts among asteroidal objects would have altered or destroyed pre-existing organic matter in both targets and projectiles to a greater or lesser degree depending upon impact velocities. To begin filling a knowledge gap on the shock metamorphism of organic compounds, we are studying the effects of shock impacts on selected classes of organic compounds utilizing laboratory shock facilities. Our approach is to subject mixtures of organic compounds, embedded in the matrix of the Murchison meteorite, to simulated hypervelocity impacts by firing them into targets at various pressures. The mixtures are then analyzed to determine the amount of each compound that survives as well as to determine if new compounds are being synthesized. The initial compounds added to the matrix (with the exception of thiosulfate). The sulfonic acids were chosen in part because they are relatively abundant in Murchison, relatively stable, and because they and the phosphonic acids are the first well-characterized homologous series of organic sulfur and phosphorus compounds identified in an extraterrestrial material. Experimental procedures were more fully described in the original proposal. A 20 mm gun, with its barrel extending into a vacuum chamber (10(exp -2) torr), was used to launch the projectile containing the sample at approx. 1.6 km/sec (3,600 mi/hr) into the target material. Maximum pressure of impact depend on target/projectile materials. The target was sufficiently thin to assure minimum pressure decay over the total sample thickness.

  2. Parental Perceptions of Body Mass Index Notification: A Qualitative Study

    ERIC Educational Resources Information Center

    Schwartz, Misty

    2015-01-01

    Background: There is a worldwide epidemic of obesity in children. To address obesity in children, emphasis must be on factors within family, school, and community environments. Although most parents and school officials are aware of the problem of overweight children, there are few data available to guide decision making about the acceptability of…

  3. Of natural bodies and antibodies: Parents' vaccine refusal and the dichotomies of natural and artificial.

    PubMed

    Reich, Jennifer A

    2016-05-01

    Despite eliminating incidences of many diseases in the United States, parents are increasingly rejecting vaccines for their children. This article examines the reasons parents offer for doing so. It argues that parents construct a dichotomy between the natural and the artificial, in which vaccines come to be seen as unnecessary, ineffective, and potentially dangerous. Using qualitative data from interviews and observations, this article shows first, how parents view their children's bodies, particularly from experiences of birth and with infants, as naturally perfect and in need of protection. Second, parents see vaccines as an artificial intervention that enters the body unnaturally, through injection. Third, parents perceive immunity occurring from illness to be natural and superior and immunity derived from vaccines as inferior and potentially dangerous. Finally, parents highlight the ways their own natural living serves to enhance their children's immunity rendering vaccines unnecessary. Taken together, this dichotomy allows parents to justify rejection of vaccines as a form of protecting children's health. These findings expose perceptions of science, technology, health, and the meanings of the body in ways that can inform public health efforts.

  4. Perceived parenting behaviours predict young adolescents' nutritional intake and body fatness.

    PubMed

    Kim, Mi-Jeong; McIntosh, William A; Anding, Jenna; Kubena, Karen S; Reed, Debra B; Moon, Gap-Soon

    2008-10-01

    This study investigated whether perceptions of parenting behaviours predict young adolescents' nutritional intake and body fatness. The randomly selected study sample consisted of 106 13-15 years olds from Houston Metropolitan Statistical Area. Parenting style variables were created by cluster analysis and factor analysis. A two-cluster solution for both maternal and paternal parenting style represented authoritative vs. non-authoritative parenting. Two parenting dimension factors derived were maternal/paternal nurturing and control. For adolescents' energy and nutrient intake, greater maternal nurturing appeared to be most beneficial given its association with lower consumption of total kilocalorie and lower saturated fat intake. Paternal nurturing was associated with lower sodium intake, whereas paternal control predicted lower percentage of kilocalories from carbohydrate and percentage Dietary Reference Intake for dietary fibre, and greater percentage of kilocalories from total fat. Maternal authoritative parenting and lower maternal control over their adolescents may have protective effects against having heavier and fatter adolescents given their associations with adolescents' body weight, sub-scapular skinfold, waist circumference, body mass index, and the tendencies of being at risk of overweight and being overweight. None of paternal parenting styles or dimensions appeared to be significantly related to adolescents' body fatness. PMID:18811793

  5. Perceived parenting behaviours predict young adolescents' nutritional intake and body fatness.

    PubMed

    Kim, Mi-Jeong; McIntosh, William A; Anding, Jenna; Kubena, Karen S; Reed, Debra B; Moon, Gap-Soon

    2008-10-01

    This study investigated whether perceptions of parenting behaviours predict young adolescents' nutritional intake and body fatness. The randomly selected study sample consisted of 106 13-15 years olds from Houston Metropolitan Statistical Area. Parenting style variables were created by cluster analysis and factor analysis. A two-cluster solution for both maternal and paternal parenting style represented authoritative vs. non-authoritative parenting. Two parenting dimension factors derived were maternal/paternal nurturing and control. For adolescents' energy and nutrient intake, greater maternal nurturing appeared to be most beneficial given its association with lower consumption of total kilocalorie and lower saturated fat intake. Paternal nurturing was associated with lower sodium intake, whereas paternal control predicted lower percentage of kilocalories from carbohydrate and percentage Dietary Reference Intake for dietary fibre, and greater percentage of kilocalories from total fat. Maternal authoritative parenting and lower maternal control over their adolescents may have protective effects against having heavier and fatter adolescents given their associations with adolescents' body weight, sub-scapular skinfold, waist circumference, body mass index, and the tendencies of being at risk of overweight and being overweight. None of paternal parenting styles or dimensions appeared to be significantly related to adolescents' body fatness.

  6. Parenting to prevent body dissatisfaction and unhealthy eating patterns in preschool children: a Delphi consensus study.

    PubMed

    Hart, Laura M; Damiano, Stephanie R; Chittleborough, Philip; Paxton, Susan J; Jorm, Anthony F

    2014-09-01

    Interventions to prevent body dissatisfaction and unhealthy eating patterns are needed in early childhood. Identifying effective parenting strategies would be useful for parents and prevention researchers. To develop expert consensus, an online Delphi study was conducted with experts (N=28, Mage=44.34) who rated statements describing potential parenting strategies gleaned from a systematic literature search. If 90-100% rated a statement as either Essential or Important, it was endorsed as a guideline. From a total of 335 statements 153 were endorsed. Despite some areas of disagreement, including whether parents should weigh their child or discourage weighing, experts were able to reach consensus on a wide range of issues, such as how to discuss healthy eating with children. The developed guidelines provide a novel and required resource for parents, and a framework for researchers developing interventions to prevent the onset of body dissatisfaction and unhealthy eating patterns in early childhood. PMID:25084034

  7. Evidence for a Carbonaceous Chondrite Parent Body With Near-TFL Oxygen Isotopes From Unique Metachondrite Northwest Africa 2788

    NASA Astrophysics Data System (ADS)

    Bunch, T. E.; Irving, A. J.; Rumble, D.; Korotev, R. L.

    2006-12-01

    Metachondrites: Metachondrites are newly recognized groups of stony meteorites that lack chondrules, but which have elemental and oxygen isotopic compositions and textures suggesting that they have been transformed by metamorphism or partial melting from precursor ordinary and carbonaceous chondrites on relatively large parent bodies [1]. The best known examples have affinities to CR (e.g., LEW 88763), CV (e.g., NWA 3133), H, L and LL chondrites; conversely there is evidence that winonaites and acapulcoites also are metachondrites derived from chondritic precursors (represented by rare chondrites such as NWA 1463 and Monument Draw). With increased sampling of new meteorites from both hot and cold desert regions, there is an emerging realization that the early solar system was populated with many relatively large differentiated planetary bodies complete with metallic cores, silicate mantles and chondritic regoliths of various types. The affinity of a particular metachondrite to a specific chondrite class relies mainly on oxygen isotopic analysis combined with distinctive elemental ratios in bulk rocks and constituent minerals (notably Fe/Mn and Ca/Na ratios, which are quite different for ordinary vs. various carbonaceous chondrite classes). Northwest Africa 2788: This specimen exhibits a metamorphic texture with triple grain junctions (grain size is mostly <0.5 mm, a few grains reach nearly 1 mm), and is composed of orthopyroxene (63 vol.%, Fs18.0Wo1.3, FeO/MnO = 30), olivine (27 vol.%, Fa21.4, FeO/MnO = 57-61), clinopyroxene (5 vol.%, Fs7.4Wo49.8, TiO2 = 0.74 wt.%, Cr2O3 = 0.63 wt.%, FeO/MnO = 19), plagioclase (5 vol.%, An53.9Or3), and accessory merrillite, troilite and metal. Replicate oxygen isotopic analyses of acid-washed bulk samples by laser fluorination gave δ18O = 6.004, 6.082; δ17O = 3.082, 3.102; Δ17O = -0.076, -0.097 per mil (for TFL slope of 0.526); these values plot close to but below the TFL. The elevated Fe/Mn ratios in the mafic silicates coupled

  8. Microfossils and biomolecules in carbonaceous meteorites: possibility of life in water-bearing asteroids and comets

    NASA Astrophysics Data System (ADS)

    Hoover, Richard B.

    2014-09-01

    It is well established that carbonaceous meteorites contain water, carbon, biogenic elements and a host of organic chemicals and biomolecules. Several independent lines of evidence indicate that the parent bodies of the CI1 and CM2 carbonaceous meteorites are most probably the C-type asteroids or cometary nuclei. Several of the protein amino acids detected in the meteorites exhibit chirality and have an excess of the L-enantiomer -- such as in the amino acids present in the proteins of all known life forms on Earth. Isotopic studies have established that the amino acids and nucleobases in the CI1 and CM2 carbonaceous meteorites are both indigenous and extraterrestrial. Optical and Scanning Electron Microscopy studies carried out by researchers during the past half century have revealed the presence of complex biogenic microstructures embedded in the rock-matrix of many of carbonaceous meteorites similar to extinct life-forms known as acritarchs and hystrichospheres. Carbonaceous meteorites also contain a wide variety of large filaments that exhibit the complex morphologies and correct size ranges of known genera and species of photosynthetic microorganisms such as cyanobacteria and diatoms. However, EDAX investigations have shown that these carbon-rich filaments typically have nitrogen content below the level of detection (<0.5% atomic) of the instrument. EDAX studies of living and dead terrestrial biological materials have shown that nitrogen can be detected in ancient mummies and tissue, hair and teeth of Pleistocene Mammoths. Hence, the absence of detectable nitrogen in the filaments provides direct evidence that they do not represent recent biological contaminants that invaded these meteorite stones after they were observed to fall to Earth. The spectral and fluorescence properties of pigments found in several species of terrestrial cyanobacteria which are similar to some microfossils found in carbonaceous meteorites may provide valuable clues to help search

  9. Microfossils, biomolecules and biominerals in carbonaceous meteorites: implications to the origin of life

    NASA Astrophysics Data System (ADS)

    Hoover, Richard B.

    2012-11-01

    Environmental and Field Emission Scanning Electron Microscopy (ESEM and FESEM) investigations have shown that a wide variety of carbonaceous meteorites contain the remains of large filaments embedded within freshly fractured interior surfaces of the meteorite rock matrix. The filaments occur singly or in dense assemblages and mats and are often encased within carbon-rich, electron transparent sheaths. Electron Dispersive X-ray Spectroscopy (EDS) spot analysis and 2D X-Ray maps indicate the filaments rarely have detectable nitrogen levels and exhibit elemental compositions consistent with that interpretation that of the meteorite rock matrix. Many of the meteorite filaments are exceptionally well-preserved and show evidence of cells, cell-wall constrictions and specialized cells and processes for reproduction, nitrogen fixation, attachment and motility. Morphological and morphometric analyses permit many of the filaments to be associated with morphotypes of known genera and species of known filamentous trichomic prokaryotes (cyanobacteria and sulfur bacteria). The presence in carbonaceous meteorites of diagenetic breakdown products of chlorophyll (pristane and phytane) along with indigenous and extraterrestrial chiral protein amino acids, nucleobases and other life-critical biomolecules provides strong support to the hypothesis that these filaments represent the remains of cyanobacteria and other microorganisms that grew on the meteorite parent body. The absence of other life-critical biomolecules in the meteorites and the lack of detectable levels of nitrogen indicate the filaments died long ago and can not possibly represent modern microbial contaminants that entered the stones after they arrived on Earth. This paper presents new evidence for microfossils, biomolecules and biominerals in carbonaceous meteorites and considers the implications to some of the major hypotheses for the Origin of Life.

  10. Magnetite in Stardust Terminal Grains: Evidence for Hydrous Alteration in the Wild2 Parent Body

    NASA Astrophysics Data System (ADS)

    Bridges, J. C.; Hicks, L. J.; MacArthur, J. L.; Price, M. C.; Burchell, M. J.; Franchi, I. A.; Gurman, S. J.

    2015-10-01

    We use synchrotron X-ray Diffraction and other techniques to show the presence of magnetite in terminal grains from Stardust cometary tracks. This suggests that the parent body of Comet Wild2 underwent hydrous alteration, and gives further evidence for the varied mineralogical history of this early Solar System body from the Outer Solar System.

  11. Controlling parental feeding practices and child body composition in ethnically and economically diverse preschool children.

    PubMed

    Wehrly, Sarah E; Bonilla, Chantal; Perez, Marisol; Liew, Jeffrey

    2014-02-01

    Controlling parental feeding practices may be associated with childhood overweight, because coercive or intrusive feeding practices may negatively impact children's development of self-regulation of eating. This study examined pressuring or forcing a child (healthy or unhealthy foods) and restricting child from unhealthy or snack foods as two types of controlling feeding practices that explain unique variances in measures of child body composition (BMI, percent body fat, and parental perception of child weight). In an ethnically and economically diverse sample of 243 children aged 4-6years old and their biological parents (89% biological mothers, 8% biological fathers, and 3% step or grand-parent), descriptive statistics indicate ethnic and family income differences in measures of feeding practices and child body composition. Additionally, the two "objective" indices of body composition (BMI and percent body fat) were related to low pressure to eat, whereas the "subjective" index (perceived child weight) was related to restriction. Regression analyses accounting for ethnic and family income influences indicate that pressure to eat and restriction both explained unique variances in the two "objective" indices of body composition, whereas only restriction explained variance in perceived child weight. Findings have implications for helping parents learn about feeding practices that promote children's self-regulation of eating that simultaneously serves as an obesity prevention strategy. PMID:24269508

  12. Early solar system aqueous activity - Sr isotope evidence from the Orgueil CI meteorite

    NASA Technical Reports Server (NTRS)

    Macdougall, J. D.; Lugmair, G. W.; Kerridge, J. F.

    1984-01-01

    The Sr isotopic composition and Rb-87/Sr-86 ratio have been measured in carbonates and sulfate separated from the Orgueil meteorite in order to determine the time when liquid water may have acted on the parent body. Both of the studied phases probably precipitated from aqueous solution. The results show that carbonate deposition occurred contemporaneously with parent body formation or shortly after it, probably within 100 Myr. On the other hand, at least some of the calcium sulfate seems to have been formed recently.

  13. Parenting Styles and Body Mass Index Trajectories From Adolescence to Adulthood

    PubMed Central

    Fuemmeler, Bernard F.; Yang, Chongming; Costanzo, Phil; Hoyle, Rick H.; Ph.D.; Siegler, Ilene C.; Williams, Redford B.; Østbye, Truls

    2013-01-01

    Objective Parenting styles such as authoritarian, disengaged, or permissive are thought to be associated with greater adolescent obesity risk than an authoritative style. This study assessed the relationship between parenting styles and changes in body mass index (BMI) from adolescence to young adulthood. Methods The study included self-reported data from adolescents in the National Longitudinal Study of Adolescent Health. Factor mixture modeling, a data-driven approach, was used to classify participants into parenting style groups based on measures of acceptance and control. Latent growth modeling (LGM) identified patterns of developmental changes in BMI. After a number of potential cofounders were controlled for, parenting style variables were entered as predictors of BMI trajectories. Analyses were also conducted for males and females of three racial/ethnic groups (Hispanic, black, white) to assess whether parenting styles were differentially associated with BMI trajectories in these 6 groups. Results Parenting styles were classified into 4 groups: authoritarian, disengaged, permissive, and balanced. Compared with the balanced parenting style, authoritarian and disengaged parenting styles were associated with a less steep average BMI increase (linear slope) over time, but also less leveling off (quadratic) of BMI over time. Differences in BMI trajectories were observed for various genders and races, but the differences did not reach statistical significance. Conclusions Adolescents who reported having parents with authoritarian or disengaged parenting styles had greater increases in BMI as they transitioned to young adulthood despite having a lower BMI trajectory through adolescence. PMID:22545979

  14. The Nakhlites. I - Petrography and mineral chemistry. II - Where, when, and how. [stony meteorites

    NASA Technical Reports Server (NTRS)

    Bunch, T. E.; Reid, A. M.

    1975-01-01

    The two Nakhlite meteorites (Nakhla and Lafayette) are described, and their possible origin is discussed. It is shown that both objects are cumulates of clinopyroxene with augite as the major mineral and with lesser abundances of olivine, plagioclase, K-feldspar, Fe-Ti oxides, FeS, pyrite, chalcopyrite, and possibly iddingsite. Also, both meteorites are unbrecciated, and their texture is dominated by elongate subhedral to euhedral prisms of clinopyroxene. The data are shown to be compatible with the Nakhlites' being cumulative rocks from a common basaltic parent liquid. It is established that these objects are not of lunar origin, and it is concluded that the position of the parent body relative to other planetary bodies remains to be determined.

  15. Nitrogen Isotopic Composition of Metal and Graphite Separates from the EL Taco (IAB) Iron Meteorite

    NASA Astrophysics Data System (ADS)

    Zipfel, J.; Mathew, K. J.; Marti, K.

    1996-03-01

    Nitrogen isotopic compositions of iron meteorites were studied by several authors to address the question of the origin of iron meteorites and their genetic relationships. It was concluded that parent body processes have only a slight effect on the primary signatures. All these results are only based on the N composition of the matrix metal. No systematic study has been performed to determine effects of parent body processes on the N isotopes in the presence of silicate inclusions. Nitrogen signatures, reflecting isotopic disequilibrium, were previously observed in Acapulco. We report first results of a detailed study of the N isotopic composition in silicate and metal phases of the IAB iron El Taco. Metal and graphite separates were analyzed by stepwise pyrolysis followed by several combustion steps using a static mass spectrometer. The new data reveal a large scale disequilibrium among the investigated phases.

  16. Thermal evolution and physics of melt extraction on the ureilite parent body

    NASA Astrophysics Data System (ADS)

    Wilson, Lionel; Goodrich, Cyrena Anne; Van Orman, James A.

    2008-12-01

    We develop a physical model of the thermal history of the ureilite parent body (UPB) that numerically tracks the history of its heating, hydration, dehydration, partial melting and smelting as a function of its formation time and the initial values of its composition, formation temperature and water ice content. Petrologic and chemical data from the main group (non-polymict) ureilite meteorites, which sample the interior of the UPB between depths corresponding to pressures in the range 3-10 MPa, are used to constrain the model. We find that to achieve the ˜30% melting inferred for ureilites from all sampled depths, the UPB must have had a radius between ˜80 and ˜130 km and must have accreted about 0.55 Ma after CAI formation. Melting began in the body at ˜1 Ma after CAI, and the time at which 30% melting was reached varied with depth in the asteroid but was always between ˜4.5 and ˜5.8 Ma after CAI. The total rate at which melt was produced in the UPB varied from more than 100 m 3 s -1 in the very early stages of melting at ˜1 Ma after CAI to ˜5 m 3 s -1 between 2 and 3 Ma after CAI, decreasing to extremely small values as the end of melting was approached beyond ˜5 Ma. Although the initial period of high melt production occupied only a short time around 1 Ma after CAI, it corresponded to ˜half (16%) of total silicate melting, and all strictly basaltic (i.e. plagioclase-saturated) melts must have been produced during this period. A very efficient melt transport network, consisting of a hierarchy of veins and larger pathways (dikes), developed quickly at the start of melting, ensuring rapid (timescales of months) transport of any single parcel of melt to shallow levels, thus ensuring that chemical interaction between melts and the rocks through which they subsequently passed was negligible. Volatile (mainly carbon monoxide) production due to smelting began at the start of silicate melting in the shallowest parts of the UPB and at later times at greater

  17. Chemical energy in cold-cloud aggregates - The origin of meteoritic chondrules

    NASA Technical Reports Server (NTRS)

    Clayton, D. D.

    1980-01-01

    If interstellar particles and molecules accumulate into larger particles during the collapse of a cold cloud, the resulting aggregates contain a large store of internal chemical energy. It is here proposed that subsequent warming of these accumulates leads to a thermal runaway when exothermic chemical reactions begin within the aggregate. These, after cooling, are the crystalline chondrules found so abundantly within chondritic meteorites. Chemical energy can also heat meteoritic parent bodies of any size, and both thermal metamorphism and certain molten meteorites are proposed to have occurred in this way. If this new theory is correct, (1) the model of chemical condensation in a hot gaseous solar system is eliminated, and (2) a new way of studying the chemical evolution of the interstellar medium has been found. A simple dust experiment on a comet flyby is proposed to test some features of this controversy.

  18. Neon isotope studies of Fayetteville and Kapoeta meteorites and clues to ancient solar activity

    NASA Technical Reports Server (NTRS)

    Padia, J. T.; Rao, M. N.

    1989-01-01

    Under the assumption that the solar-flare bombardment of the irradiated grains of gas-rich meteorites occurred about 4.5 b.y. ago on the parent body regoliths at 3 A.U., an estimate of the solar cosmic ray-produced Ne-21 is made by studying etched pyroxene minera separates from both light and dark portions of the gas-rich meteorites Fayetteville and Kapoeta. Excesses of solar cosmic ray Ne-21 were observed in dark portions of these meteorites, after accounting for their galactic cosmic ray Ne-21 production and solar flare Ne-21. In order to produce the estimated solar cosmic ray Ne-21 in the present samples, highly enhanced solar cosmic ray proton fluxes from the ancient sun are required.

  19. 187Os/186Os in Lunar and Meteoritic Materials

    NASA Astrophysics Data System (ADS)

    Birck, J. L.; Allegre, C. J.

    1993-07-01

    The unique potentiallity of the ^187Re-^1870s radiochronometer stems from the chemical properties of the 2 elements. Their siderophilic nature has made the dating of the metal phase of iron meteorites and chondrites possible [1,2]. In silicate crystallization or melting, Os behaves as a strongly compatible element [3]. For Re the results hereunder show that its behavior is highly variable, depending on context. The development of the highly sensitive negative thermal ionization mass spectrometry [4,5] made possible the extensive analysis of silicate materials. We developed a chemical separation method allowing the analysis of 0,5 g of silicate with an Os blank of 0.3 pg (1pg=10^-12 g). The isotopic measurement of Os has a typical precision of a few permil for 1 pg of Os. A variety of samples has been investigated. Iron Meteorites: The main purpose of this study was to shed some light on the history of Kodaikanal. The silicate inclusions of this meteorite were reset at 3.7 Ga for both the Rb-Sr and the U-Pb chronometers [6,7]. The data from Coahuila, Canyon Diablo, Tlacotepec, and North Chile plot within 1% on the same isochron along with 3 samples from 2 locations inside the meteorite of Kodaikanal. As a consequence the Kodaikanal parent body did not form at 3.7 Ga but at about the same time as the parent bodies of the the majority of the other iron meteorites (~4.5 Ga). The only difference is that Kodaikanal suffered a strong secondary event at 3.7 Ga, which reset Rb/Sr and U-Pb chronometers but did not fractionate the Re/Os ratio. This result has already been suggested by our earlier work [8]. The St Severin Chondrite: A bulk sample and several batches of the metal separated from this chondrite were analysed. They plot on the iron meteorite isochron. However this metal is heterogeneous in Re/Os by a factor of at least 2 and indicates an uncomplete homogeinization of Re/Os between metal grains during parent body metamorphism. Basaltic Materials: Basaltic

  20. SNC meteorites - Igneous rocks from Mars

    NASA Technical Reports Server (NTRS)

    Wood, C. A.; Ashwal, L. D.

    1982-01-01

    It is argued that SNC (shergottite, nakhlite, chassignite) meteorites are ejecta from Mars. The mineralogy and chemistry of these objects is discussed, including rare earth element content, potassium/uranium ratios, oxidation state, oxygen isotopes, ages and isotopic evolution, magnetism, shock and texture. The possibility of SNC's deriving from Mercury, Venus, earth, moon, or a eucrite parent body is argued against. Mercury is too volatile-poor and anhydrous, Venus's atmosphere too thick and hot and its gravitational field too large, earth's oxygen isotope content too different from that of SNC's, the moon too different isotopically and chemically, and the ages of eucrites too different. Models suggest that SNC's could have escaped from Mars's gravitational field, and their composition supports Martian origin. Statistically, they could have reached the earth within their measured shock ages. Objections to the hypothesis are also discussed.

  1. Mineralogical Characterization Of 150 S-type Asteroids And Comparison With OC Meteorites

    NASA Astrophysics Data System (ADS)

    Vernazza, Pierre; Binzel, R. P.; DeMeo, F. E.; Thomas, C. A.

    2007-10-01

    An important goal of asteroid science is to link meteorites and their immediate precursors back to their parent bodies. To accomplish this task, we need to combine data from several different disciplines: dynamical modeling, spectroscopic observations, petrology, and mineralogy. In this regard, a major question that spectroscopy can help to answer is `How well do meteorites sample the asteroid belt?' Over the last four years, more than 300 asteroids have been observed in the 0.4-2.5 micron range (Demeo et al. 2007; this meeting). Among them, 150 objects belong to the S complex. We compared the mineralogical composition of all these S-type asteroids with the composition of OC meteorites in order to bring an answer to our question. First, we applied the Shkuratov et al. (1999) model to an OC sample from RELAB (19 H chondrites, 27 L chondrites and 11 LL chondrites). This allowed us to constrain the relative abundance of olivine and orthopyroxene for these meteorites as well as the chemistry of these minerals (Mg number). Second, we applied the same model with the same optical constants to our asteroid sample. We also used the Brunetto et al. (2006) in order to model the spectral reddening (if present) due to space weathering processes. We find that a major fraction (>70%) of the S-type asteroids has a composition (in terms of olivine and orthopyroxene percentage) that is clearly compatible with OC meteorites. Since our S-type sample includes both near-Earth and main-belt asteroids, it suggests that ordinary chondrites have a broad source region (as opposed to being derived from a few specially placed parent bodies). Yet we have an unsolved conundrum: the majority of our asteroid model fits suggest an LL-chondrite meteorite analog, even though this group comprises only 10% of all ordinary chondrite falls. Possible solutions will be presented.

  2. The formation of plessite in meteoritic metal

    NASA Astrophysics Data System (ADS)

    Goldstein, J. I.; Michael, J. R.

    2006-04-01

    Plessite is a mixture of body-centered cubic (bcc) kamacite (α), face-centered cubic (fcc) taenite (γ), and/or ordered FeNi-tetrataenite (γ') phases and is observed in the metal of iron, stony-iron, and chondritic meteorites. The formation of plessite was studied by measuring the orientation of the bcc and fcc phases over large regions of plessite using electron backscatter diffraction (EBSD) analysis in five ataxites, the Carlton IAB-IIICD iron, and zoneless plessite metal in the Kernouve H6 chondrite.The EBSD results show that there are a number of different orientations of the bcc kamacite phase in the plessite microstructure. These orientations reflect the reaction path γ (fcc) → α2 (bcc) in which the α2 phase forms during cooling below the martensite start temperature, Ms, on the close-packed planes of the parent fcc phase according to one or more of the established orientation relationships (Kurdjumov-Sachs, Nishiyama-Wasserman, and Greninger-Troiano) for the fcc to bcc transformation.The EBSD results also show that the orientation of the taenite and/or tetrataenite regions at the interfaces of prior α2 (martensite) laths, is the same as that of the single crystal parent taenite γ phase of the meteorite. Therefore, the parent taenite γ was retained at the interfaces of martensite laths during cooling after the formation of martensite. The formation of plessite is described by the reaction γ → α2 + γ → α + γ. This reaction is inconsistent with the decomposition of martensite laths to form γ phase as described by the reaction γ → α2 → α + γ, which is the classical mechanism proposed by previous investigators. The varying orientations of the fine exsolved taenite and/or tetrataenite within decomposed martensite laths, however, are a response to the decomposition of α2 (martensite) laths at low temperature and are formed by the reaction α2 → α + γ.

  3. Noble Gases in the Chelyabinsk Meteorites

    NASA Technical Reports Server (NTRS)

    Haba, Makiko K.; Sumino, Hirochika; Nagao, Keisuke; Mikouchi, Takashi; Komatsu, Mutsumi; Zolensky, Michael E.

    2014-01-01

    The Chelyabinsk meteorite fell in Russia on February 15, 2013 and was classified as LL5 chondrite. The diameter before it entered the atmosphere has been estimated to be about 20 m [1]. Up to now, numerous fragments weighing much greater than 100 kg in total have been collected. In this study, all noble gases were measured for 13 fragments to investigate the exposure history of the Chelyabinsk meteorite and the thermal history of its parent asteroid.

  4. School Governing Bodies in South Africa: Relationships between Principals and Parent Governors--A Question of Trust?

    ERIC Educational Resources Information Center

    Heystek, Jan

    2006-01-01

    This article focuses on the relationship between principals and school governing bodies in South Africa. Although there are several different groups represented on the governing body, this article relates mainly to the role and function of the parental representatives. The parents have a majority on the governing bodies and therefore have an…

  5. A model composition for Mars derived from the oxygen isotopic ratios of martian/SNC meteorites

    NASA Astrophysics Data System (ADS)

    Delaney, J. S.

    1994-07-01

    Oxygen is the most abundant element in most meteorites, yet the ratios of its isotopes are seldom used to constrain the compositional history of achondrites. The two major achondrite groups have O isotope signatures that differ from any plausible chondritic precursors and lie between the ordinary and carbonaceous chondrite domains. If the assumption is made that the present global sampling of chondritic meteorites reflects the variability of O reservoirs at the time of planetessimal/planet aggregation in the early nebula, then the O in these groups must reflect mixing between known chondritic reservoirs. This approach, in combination with constraints based on Fe-Mn-Mg systematics, has been used previously to model the composition of the basaltic achondrite parent body (BAP) and provides a model precursor composition that is generally consistent with previous eucrite parent body (EPB) estimates. The same approach is applied to Mars exploiting the assumption that the SNC and related meteorites sample the martian lithosphere. Model planet and planetesimal compositions can be derived by mixing of known chondritic components using O isotope ratios as the fundamental compositional constraint. The major- and minor-element composition for Mars derived here and that derived previously for the basaltic achondrite parent body are, in many respects, compatible with model compositions generated using completely independent constraints. The role of volatile elements and alkalis in particular remains a major difficulty in applying such models.

  6. Organic analyses of the Murchison meteorite

    NASA Astrophysics Data System (ADS)

    Cooper, George

    Many compounds yielding clues to the organic chemistry and molecular composition of the early solar system have been identified in the Murchison meteorite. Among these are amino acid precursors: carboxy lactams, lactams, N-acetyl amino acids, and amino acid hydantoins (5-substituted hydantoins). Also found were precursors of acids: dicarboxylic acid mono amides, carboxylic acid amides, and cyclic imides. Precursors of hydroxy acids, hydroxy amides, are also numerous. Organic phosphorus compounds are reported. The corresponding organic sulfur compounds, sulfite, and water soluble and insoluble phosphate are also present. Laboratory experiments have indicated that unusual cyanate chemistry was possibly responsible for the formation of at least some of the amino and carboxylic acid precursors. A plausible mode of formation of the organic phosphorus and sulfur compounds, alkyl phosphonic and alkyl sulfonic acids, respectively, suggests a direct link between identified interstellar molecules and aqueous chemistry on the meteorite parent body. The compounds were extracted under gentle conditions to avoid, as much as possible, decomposition during extraction. The procedure included extraction of a powdered sample with room temperature water, cation and anion exchange chromatography, derivatization with the reagent N-methyl- N-(tert-butyl dimethyl silyl) trifluoro acetamide (MTBSTFA), and analysis by gas chromatography-mass spectrometry (GCMS) and high performance liquid chromatography (HPLC).

  7. Paleomagnetism of the moon and meteorites

    NASA Astrophysics Data System (ADS)

    Hood, L. L.; Cisowski, S. M.

    1983-04-01

    Paleomagnetic investigations (1979-1982) of the nature of the magnetization process and the magnetizing fields which produced magnetization in lunar and meteoritic materials are surveyed. Natural remanence magnetization (NRM), as well as thermoremanence magnetization (TRM), have been measured in carbonaceous chondrites and and L-chondrites to characterize the formation processes occurring when the magnetization was induced. Chemical remanence magnetism, together with the NRM, has been examined in noncarbonaceous chondrites, and NRM intensity and locations have been probed in achondrites. The magnetism has been concluded to arise either from solar magnetic fields, solar nebula magnetic fields, dynamo magnetic fields in the meteorite parent bodies, or locally generated fields caused by processes such as impacts. Lunar samples with NRM have been dated to origins less than 3.6 b.y., and could have been caused by shocks, such as from impacts less than 3 m.y. ago. Discussions of TRM, dynamo, and possible transient magnetic fields from hypervelocity meteoroid impacts as origins of magnetism on the surface and in a lunar magnetic core are presented.

  8. Crystallogenesis of Mixed-Valence Fe-Serpentines: Implications for Their Formation during the Aqueous Alteration of Carbonaceous Chondrites' Parent Body

    NASA Astrophysics Data System (ADS)

    Caste, F.; Elmaleh, A.; Abdelmoula, M.; Menguy, N.; Ona-Nguema, G.; Gérard, M.

    2014-12-01

    (Fe3+,Fe2+)-bearing serpentines close to the ideal endmember cronstedtite (Fe2+2,Fe3+) (Si, Fe3+) O5 (OH)4, are major components of CM2-type carbonaceous chondrites. Along with other hydrated minerals, they mostly formed during the first million years of the Solar System by aqueous alteration on the meteorite parent body. These secondary minerals could provide constraints to the processes of alteration. Here we developed a two-step protocol (room temperature gel precipitation / hydrothermal growth, in anoxic conditions) for the synthesis of Fe-serpentines with a controlled Fe2+/Fe3+ ratio in order to improve our understanding of Fe-serpentines formation. XRD analyses of the gels and electron microscopy (SEM, TEM) suggest the formation of Fe-serpentine seeds at room temperature. These germs have integrated significant amounts (up to 24%) of tetrahedral Fe3+, as indicated by Mössbauer spectroscopy. Hydrothermal growth at 60°C yields a clear improvement of crystallinity, further suggesting that Fe-serpentines form at low temperatures, lower than Mg-serpentines. We report that among the samples, whose composition covers the solid solution between greenalite (Fe2+-serpentine) and cronstedtite, crystallinity improves with the Fe/Si and the Fe3+ content, which respective roles remain to be evaluated. In chondrites' parent body, Fe is mostly released by the aqueous alteration of metallic alloys and Fe2+-bearing anhydrous silicates (mostly olivine and pyroxene) and sulfides. We suggest that the formation of cronstedtite, which is associated with the early stages of parent body alteration, might have been kinetically favored by the oxidation of Fe. This raises the question of the processes involved, in the anoxic chondritic environment.

  9. Fossils of Cyanobacteria in CI1 Carbonaceous Meteorites: Implications to Life on Comets, Europa and Enceladus

    NASA Astrophysics Data System (ADS)

    Hoover, Richard B.

    2011-10-01

    amber) indicate that nitrogen remains detectable in biological materials for many thousands of years but is undetectable in the truly ancient fossils. These studies have led to the conclusion that the filaments found in the CI1 carbonaceous meteorites are indigenous fossils rather than modern terrestrial biological contaminants that entered the meteorites after arrival on Earth. The δ13C and D/H content of amino acids and other organics found in these stones are shown to be consistent with the interpretation that comets represent the parent bodies of the CI1 carbonaceous meteorites. The implications of the detection of fossils of cyanobacteria in the CI1 meteorites to the possibility of life on comets, Europa and Enceladus are discussed.

  10. Thermal histories of CO3 chondrites - Application of olivine diffusion modelling to parent body metamorphism

    NASA Technical Reports Server (NTRS)

    Jones, Rhian H.; Rubie, David C.

    1991-01-01

    The petrologic sequence observed in the CO3 chondrite group has been suggested to be the result of thermal metamorphism on a parent body. A model developed to examine the possibility that chondrule and matrix olivines equilibrated in situ, during parent body metamorphism is presented. The model considers Fe-Mg interdiffusion between chondrule and matrix olivines. Zoning profiles comparable to those observed in chondrule olivines from partially equilibrated members of the series are reproduced successfully. Metamorphism of CO3 chondrites on a parent body is therefore a viable model for the observed equilibration. Results indicate that peak metamorphic temperatures experienced by the CO3 chondrites were around 500 C, and that the range of peak temperatures between unequilibrated and equilibrated subtypes was relatively narrow, around 100 C.

  11. Uranium-lead Isotope Evidence in the Shelyabinsk LL5 Chondrite Meteorite for Ancient and Recent Thermal Events

    NASA Technical Reports Server (NTRS)

    Lapen, T. J.; Kring, D. A.; Zolensky, M. E.; Andreasen, R.; Righter, M.; Swindle, T. D.; Beard, S. P.; Swindle, T. D.

    2014-01-01

    The impact histories on chondrite parent bodies can be deduced from thermochronologic analyses of materials and isotope systems with distinct apparent closure temperatures. It is especially critical to better understand the geological histories and physical properties of potenally hazardous near-Earth asteroids. Chelyabinsk is an LL5 chondrite meteorite that was dispersed over a wide area tens of kilometers south of the town of Chelyabinsk, Russia by an explosion at an altitude of 27 km at 3:22 UT on 15 Feb 2013 [1,2]. The explosion resulted in significant damage to surrounding areas and over 1500 injuries along with meteorite fragments being spread over a wide area [1].

  12. 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.

  13. Parenting

    MedlinePlus

    ... parents, people are always ready to offer advice. Parenting tips, parents' survival guides, dos, don'ts, shoulds ... right" way to be a good parent. Good parenting includes Keeping your child safe Showing affection and ...

  14. Parenting styles, feeding styles, and their influence on child obesogenic behaviors and body weight. A review.

    PubMed

    Vollmer, Rachel L; Mobley, Amy R

    2013-12-01

    With recommendations to include parents as targets for childhood obesity interventions, there is a need to review the relationship of general parenting influences on childhood obesity. Therefore, the aim of this review is to examine the existing literature regarding the influence of parenting style and/or feeding styles on childhood obesogenic behaviors and body weight. Research articles related to parenting style (n=40) and parental feeding style (n=11) were identified and reviewed. An authoritative style appears to be the most protective parenting and feeding style while the indulgent feeding style is consistently associated with negative health outcomes. Overall, results for parenting style studies are inconsistent due to differences in conceptualization and measurement, while the results for feeding styles are much more cohesive. The literature is lacking in the ability to describe the interplay between parenting and feeding styles and child obesity risk. Recommendations for future research and interventions are discussed in regards to feeding style and influences on childhood obesity. PMID:24001395

  15. Accretion, Differentiation, and Impact Processes on the Ureilite Parent Body

    NASA Technical Reports Server (NTRS)

    Downes, Hilary; Herrin, J. S.; Hudon, P.; Mittlefehldt, D.W.

    2007-01-01

    Ureilites are primitive ultramafic achondrites composed largely of olivine and pigeonite, with minor augite, orthopyroxene, carbon, sulphide and metal. They represent very early material in the history of the Solar System and (in common with lodranites and acapulcoites) form a bridge between undifferentiated chondrites and fully differentiated asteroidal bodies. They show an intriguing mixture of chemical characteristics, some of which are considered to be nebula-derived (e.g. variations in Delta(sup 17)O and mg#) whereas others have been imposed by asteroidal differentiation (e.g. core formation, silicate partial melting, removal of basalt).

  16. 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

  17. Racial-Ethnic Differences in Parental Body Image Perceptions of Preschoolers: Implications for Engaging Minority Parents in Weight-Related Discussions

    PubMed Central

    Hernandez, Raquel G.; Garcia, Janelle; Thompson, Darcy A.

    2016-01-01

    Parental misperception of minority preschoolers’ body image remains a major barrier to obesity prevention. Differences in child body image perception between Latino and African-American parents may inform etiologies to obesity disparities. Using pooled data from studies implementing validated child body sketches, frequency of parental misperception in these two populations are analyzed and associations with provider commentary and parental acculturation reported. Two convenience samples were utilized (Latino parents: n=73, African-American parents: n=150). Over half of Latino parents (58%) compared to 5% of African-American parents misperceived their obese child as lighter than a healthy weight (p=.002). In contrast to our prior study, provider commentary was not associated with reduced risk of misperception in Latino parents. Misperception occurred most frequently in mild-moderately acculturated Latino parents. Increased rates of misperception and limitations on the potential role of the provider commentary indicate a critical need to better strategize communication with low-income, moderately acculturated Latino parents. PMID:25609097

  18. Perceptions of body image by persons with Prader-Willi syndrome and their parents.

    PubMed

    Napolitano, Deborah A; Zarcone, Jennifer; Nielsen, Sarah; Wang, Hongyue; Caliendo, Jillian Maynard

    2010-01-01

    Prader-Willi syndrome is a genetic disorder characterized by obesity. The Figure Rating Scale (Stunkard, Sorensen, & Schulsinger, 1983) was completed by 43 individuals with this syndrome to determine their level of dissatisfaction with their body. Their parents also completed this scale regarding their child to determine whether they were dissatisfied with their child's body status. Results showed that individuals with Prader-Willi syndrome were dissatisfied with their body. Parents also were dissatisfied with their child's body. Results of this study demonstrate that the responses of persons with Prader-Willi syndrome on the Figure Rating Scale show significant discrepancies between how they think they look and how they wished they looked. PMID:20025358

  19. Perceptions of Body Image by Persons With Prader-Willi Syndrome and Their Parents

    PubMed Central

    Napolitano, Deborah A.; Zarcone, Jennifer; Nielsen, Sarah; Wang, Hongyue; Caliendo, Jillian Maynard

    2010-01-01

    Prader-Willi syndrome is a genetic disorder characterized by obesity. The Figure Rating Scale (Stunkard, Sorensen, & Schulsinger, 1983) was completed by 43 individuals with this syndrome to determine their level of dissatisfaction with their body. Their parents also completed this scale regarding their child to determine whether they were dissatisfied with their child’s body status. Results showed that individuals with Prader-Willi syndrome were dissatisfied with their body. Parents also were dissatisfied with their child’s body. Results of this study demonstrate that the responses of persons with Prader-Willi syndrome on the Figure Rating Scale show significant discrepancies between how they think they look and how they wished they looked. PMID:20025358

  20. Enantiomeric excesses of chiral amines in ammonia-rich carbonaceous meteorites

    NASA Astrophysics Data System (ADS)

    Pizzarello, Sandra; Yarnes, Christopher T.

    2016-06-01

    Chiral homogeneity is essential to the structure and function of terrestrial biopolymers but the origin of this "homochirality" is poorly understood and remains one of the many unknowns surrounding the origins of life. Several amino acids extracted from Carbonaceous Chondrite meteorites display L-enantiomeric excesses (ee) and their findings have encouraged suggestions that an input of non-racemic meteoritic compounds to early Earth might have led to terrestrial homochirality. Motivated by occasional indications of possible ee in other classes of soluble meteoritic compounds, we have undertaken a systematic study of the chiral distribution of amines in Renazzo-type (CR) meteorites, where they are the second most abundant organic molecular species and ammonia is by far the most abundant single molecule. We report here the first time finding of L-ee for two chiral amines in several pristine CR meteorites from Antarctica and outline a proposal by which the compounds possibly formed from the same ketone precursors as some of the chiral amino acids. This would occur during a warm hydrous stage of the asteroidal parent body, via a reductive amination process in the presence of a large abundance of ammonia, where the precursors' adsorption upon mineral phases possessing asymmetry offered the opportunity for chiral induction. Because the precursor ketones are achiral, the proposal underscores the likelihood of diverse asymmetric influences and processes in cosmochemistry.

  1. Possible effects of diagenesis on the stable isotope composition of amino acids in carbonaceous meteorites

    NASA Astrophysics Data System (ADS)

    Engel, Michael H.

    2015-09-01

    The initial report of indigenous, non-racemic protein amino acids (L-enantiomer excess) in the Murchison meteorite was based on the fact that only eight of the twenty amino acids characteristic of all life on Earth was present in this stone1. The absence of the other protein amino acids indicated that contamination subsequent to impact was highly unlikely. The development of new techniques for determining the stable isotope composition of individual amino acid enantiomers in the Murchison meteorite further documented the extraterrestrial origins of these compounds2,3. The stable isotope approach continues to be used to document the occurrence of an extraterrestrial L-enantiomer excess of protein amino acids in other carbonaceous meteorites4. It has been suggested that this L-enantiomer excess may result from aqueous reprocessing on meteorite parent bodies4,5. Preliminary results of simulation experiments are presented that are used to determine the extent to which the stable isotope compositions of amino acid constituents of carbonaceous meteorites may have been altered by these types of diagenetic processes subsequent to synthesis.

  2. Isotopic Measurements of Organic Sulfonates From The Murchison Meteorite

    NASA Technical Reports Server (NTRS)

    Cooper, G. W.; Chang, S.; DeVincenzi, Donald L. (Technical Monitor)

    1995-01-01

    Organic sulfonates and phosphonates have been extracted from the Murchison meteorite for stable isotope measurements. Preliminary stable isotope measurements of individual alkyl sulfonates, R-SO3H (R=C(sub n)H(sub 2n+l)), are shown. These compounds were found in aqueous extracts of Murchison. Both groups show trends similar to other homologous series of organic compounds indigenous to Murchison. Molecular abundances decrease with increasing carbon number, and all possible isomers at each carbon number (through C-4) are present. Carbon isotope measurements of the sulfonates show a decrease in the C-13/C-12 ratio with increasing carbon number. The overall objectives of this project are to obtain dime element carbon, hydrogen, and sulfur - intramolecular isotopic analyses of individual sulfonates, and isotopic measurement of carbon and hydrogen of the phosphonates as a group. The Murchison meteorite is the best characterized carbonaceous chondrite with respect to organic chemistry. The finding of organic sulfonates and phosphonates in Murchison is of interest because they are the first well-characterized series of sulfur and phosphorus containing organic compounds found in meteorites. Also, meteorites, comets, and interplanetary dust particles may have been involved in chemical evolution on the early Earth. Because of the critical role of organic phosphorus and sulfur in all living systems, it is particularly interesting to see examples of abiotic syntheses of these classes of compounds. The study of the isotopic composition of the sulfonates and phosphonates can yield insight into their possible interstellar origin as well as their mechanisms of synthesis in the early solar system. Previous isotopic analyses of other classes of organic compounds indigenous to meteorites, e.g., amino acids, carboxylic acids, and hydrocarbons indicate the possibility that interstellar molecules were incorporated into meteorite parent bodies. In these compounds the ratios of heavy to

  3. Indigenous aliphatic amines in the aqueously altered Orgueil meteorite

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    The CI1 Orgueil meteorite is a highly aqueously altered carbonaceous chondrite. It has been extensively studied, and despite its extensive degree of aqueous alteration and some documented instances of contamination, several indigenous organic compounds including amino acids, carboxylic acids, and nucleobases have been detected in its carbon-rich matrix. We recently developed a novel gas chromatographic method for the enantiomeric and compound-specific isotopic analyses of meteoritic aliphatic monoamines in extracts and have now applied this method to investigate the monoamine content in Orgueil. We detected 12 amines in Orgueil, with concentrations ranging from 1.1 to 332 nmol g-1 of meteorite and compared this amine content in Orgueil with that of the CM2 Murchison meteorite, which experienced less parent-body aqueous alteration. Methylamine is four times more abundant in Orgueil than in Murchison. As with other species, the amine content in Orgueil extracts shows less structural diversity than that in Murchison extracts. We measured the compound-specific stable carbon isotopic ratios (δ13C) for 5 of the 12 monoamines detected in Orgueil and found a range of δ13C values from -20 to +59‰. These δ13C values fall into the range of other meteoritic organic compounds, although they are 13C-depleted relative to their counterparts extracted from the Murchison meteorite. In addition, we measured the enantiomeric composition for the chiral monoamines (R)- and (S)-sec-butylamine in Orgueil, and found it was racemic within experimental error, in contrast with the L-enantiomeric excess found for its amino acid structural analog isovaline. The racemic nature of sec-butylamine in Orgueil was comparable to that previously observed in Murchison, and to other CM2 and CR2 carbonaceous chondrites measured in this work (ALH 83100 [CM1/2], LON 94101 [CM2], LEW 90500 [CM2], LAP 02342 [CR2], and GRA 95229 [CR2]). These results allow us to place some constraints on the effects of

  4. Rediscovery of Polish meteorites

    NASA Astrophysics Data System (ADS)

    Tymiński, Z.; Stolarz, M.; Żołądek, P.; Wiśniewski, M.; Olech, A.

    2016-01-01

    The total number of Polish registered meteorites (by July 2016) including the meteoritical artifacts as Czestochowa Raków I and II is 22. Most of them are described by the pioneer of Polish Meteoritics Jerzy Pokrzywnicki who also identified the meteorite fall locations. In recent years prospectors found impressive specimens of known Polish meteorites such as Morasko: 34 kg, 50 kg, 164 kg, 174 kg and 261 kg or Pultusk: 1578 g, 1576 g, 1510 g, 610 g and 580 g expanding and determining precisely the known meteorite strewn fields.

  5. Metal and Bi/Pb microdistribution studies of an L3 chondrite - Their implications for a meteorite parent body

    NASA Astrophysics Data System (ADS)

    Woolum, D. S.; Burnett, D. S.

    1981-09-01

    Strong localizations relative to bulk are reported of Bi, and to a lesser extent Pb, in some of the kamacite grains in Khohar, while other kamacite grains show no such enrichments. Distinctive and correlated differences in the Ni content are found in the two kamacite populations, with the Bi/Pb-rich kamacite grains having consistently lower Ni levels than the 6-7% typical of the Bi/Pb-poor kamacite. The Bi/Pb-rich kamacite grains also exhibit a highly reactive attack upon etching, which may be due to a finely polycrystaline microstructure. It is concluded that the trace element microdistributions were not established in the nebula, and that the enrichments were not likely to have occurred with slow cooling in the presence of a vapor phase during the kamacite-taenite phase transitions.

  6. Investigation of isovaline enantiomeric excesses in CM meteorites using liquid chromatography time of flight mass spectrometry

    NASA Technical Reports Server (NTRS)

    Glavin, Daniel P.; Dworkin, Jason P.

    2003-01-01

    The enantiomeric abundances of the alpha-dialkyl amino acid isovaline were measured in the CM2 meteorites Murchison and LEW 90500 using a new liquid chromatography-time of flight-mass spectrometry (LC-ToF-MS) technique coupled with OPA/NAC derivatization and UV fluorescence detection. Previous analyses of Murchison have shown that L-enantiomeric excesses of isovaline range from 0 to 15.2% with significant variation between meteorite fragments [1]. For this study, hot water extracts of interior fragments (> 2 cm from fusion crust) of the Murchison (USNM 6650.2, mass 6 g) and LEW 90500 (split 69, parent 1, mass 5 g) carbonaceous meteorites were analyzed. Enantiomeric excesses were measured using the single ion LC-ToF-MS trace for the OPA/NAC derivative of isovaline at d z 393.15 (Fig. 1). L-isovaline excesses in these meteorite samples ranged from 18.9 to 20.5% for Murchison and -0.5 to 3.0% for LEW 90500. The measured values for Murchison are the largest enantiomeric excesses for isovaline reported to date. The enantiomeric excesses of L-isovaline cannot be the result of interference from other C5 amino acid isomers present in the meteorites or terrestrial contamination from the landing site environments. The L-isovaline excesses in Murchison are inconsistent with the synthesis of all of the isovaline by the Strecker-cyanohydrin pathway on the CM meteorite parent body. The mechanism(s) for the formation of the enantiomeric asymmetry in isovaline in Murchison are currently unknown and it is not clear how the asymmetry of alpha-dialkyl amino acids could be transferred to the a-hydrogen protein amino acids common in all life on Earth today.

  7. The Toroidal Sporadic Sources: Looking for parent bodies of meteor streams

    NASA Astrophysics Data System (ADS)

    Pokorny, Petr; Brown, Peter G.; Moorhead, Althea V.; Wiegert, Paul; Janches, Diego

    2016-10-01

    The origin and characteristics of the North toroidal (NT) and South toroidal (ST) sporadic meteoroid sources remain poorly known. The NT was first noted in radar measurements in the late 1950s, however, its origin has puzzled astronomers for more than 50 years. The ST started being more thoroughly observed in recent years. The NT and ST meteoroid population shows orbital elements unlike any known contemporary parent population in the Solar System, dominated by particles with very high inclinations, modest semi-major axis values and low eccentricities. Recently, several dynamical models have suggested that the parent bodies of the NT source may be linked to the population of Halley-type comets. However, no model to date has been able to reproduce in detail the significant temporal variations in activity seen throughout the year.In this work we present observations of the NT meteoroid source made by the Canadian Meteor Orbit Radar (CMOR) between 2011 - 2015 and of the ST source obtained with the South Argentina Agile Meteor Radar (SAAMER) between 2011 - 2015. We use these results to define in detail the temporal and orbital element variations in the activity of both sources. We also present preliminary results from a model, in which we have identified 169 near-Earth objects that are potential contributors to the NT/ST meteoroid population at the current time. Furthermore, we integrate their orbits backward in time 25,000 years. For each potential parent body, we simulate 5 clones to span the range of possible parent body orbits as a function of time. From our initial epoch 25 ka, we eject 2000 test meteoroids per 100 years of sizes 30 μm to 1 mm per potential parent clone and examine the resulting dust trail intersecting the Earth to match the various temporally distinct portions of the NT/ST meteoroid complex. We find that while some of the observed features of both sources can be modeled as distinct past contributions from individual parent bodies, many major

  8. Effects of parent-only childhood obesity prevention programs on BMIz and body image in rural preteens.

    PubMed

    Eldridge, Galen; Paul, Lynn; Bailey, Sandra J; Ashe, Carrie Benke; Martz, Jill; Lynch, Wesley

    2016-03-01

    This experiment compared body image (BI) and BMI changes resulting from two parent-only obesity prevention interventions aimed at 8-12 year olds. Parents in the experimental intervention attended ten face-to-face educational sessions, while parents in the minimal (control) intervention received similar mailed information. Parent-child dyads (N=150) were semi-randomly assigned to intervention groups. Children were assessed before, after, and 6 months following the interventions; children did not attend experimental intervention sessions. Child BI assessments included weight and size perception, weight management goals, body esteem, and appearance attitudes. Significant effects included small decreases in BMIz scores and overweight dissatisfaction, as well as improvements in aspects of body esteem and appearance attitudes. Some BI effects were gender-specific. Decreases in overweight dissatisfaction were greater following the experimental treatment. Neither treatment reduced body size misperception. Thus, parent-only obesity prevention interventions can reduce body weight and body image concerns among rural preteens.

  9. Effects of parent-only childhood obesity prevention programs on BMIz and body image in rural preteens.

    PubMed

    Eldridge, Galen; Paul, Lynn; Bailey, Sandra J; Ashe, Carrie Benke; Martz, Jill; Lynch, Wesley

    2016-03-01

    This experiment compared body image (BI) and BMI changes resulting from two parent-only obesity prevention interventions aimed at 8-12 year olds. Parents in the experimental intervention attended ten face-to-face educational sessions, while parents in the minimal (control) intervention received similar mailed information. Parent-child dyads (N=150) were semi-randomly assigned to intervention groups. Children were assessed before, after, and 6 months following the interventions; children did not attend experimental intervention sessions. Child BI assessments included weight and size perception, weight management goals, body esteem, and appearance attitudes. Significant effects included small decreases in BMIz scores and overweight dissatisfaction, as well as improvements in aspects of body esteem and appearance attitudes. Some BI effects were gender-specific. Decreases in overweight dissatisfaction were greater following the experimental treatment. Neither treatment reduced body size misperception. Thus, parent-only obesity prevention interventions can reduce body weight and body image concerns among rural preteens. PMID:26851605

  10. Chemical composition of the Howardite Parent Body deduced from Kapoeta primary 'mafic' magmas

    NASA Technical Reports Server (NTRS)

    Smith, M. R.; Schmitt, R. A.

    1982-01-01

    Chemical data are presented for three 'mafic' clasts extracted from the Kapoeta howardite. Bulk compositions and petrologic observations suggest that two of these lithic clasts represent olivine-plagioclase bearing orthopyroxenites. Chondrite-relative refractory large ion lithophile abundances of two of the clasts are inferred to represent primary Mg-rich magmas produced by extensive (greater than about 70%) partial melting of a source composition indistinguishable from the silicate fraction of average CH-CL ordinary chondrites, with the exception of the depletion of the alkalis Na and K by a factor of 13 + or - 1 in the source composition. A metal-free and volatile depleted Kapoeta Parent Body (KPB) is subsequently deduced and is shown to compare very well with other similarly derived Achondrite Parent Body and Howardite Parent Body estimates but not to parent body estimates derived from inferences based on eucrite phase equilibrium studies. Other implications suggest that the KPB is heterogeneous with respect to Fe/Mg ratios.

  11. Parental Bonds, Anxious Attachment, Media Internalization, and Body Image Dissatisfaction: Exploring a Mediation Model

    ERIC Educational Resources Information Center

    Cheng, Hsiu-Lan; Mallinckrodt, Brent

    2009-01-01

    The first purpose of this study was to investigate direct links between body image dissatisfaction (BID) in college women and their memories of either parent as cold and emotionally aloof. Theory, clinical case evidence, and a small (but growing) number of studies support these links. After estimating the strength of the associations between…

  12. Parental Bonds, Attachment Anxiety, Media Susceptibility, and Body Dissatisfaction: A Mediation Model

    ERIC Educational Resources Information Center

    Patton, Sarah C.; Beaujean, A. Alexander; Benedict, Helen E.

    2014-01-01

    The developmental trajectory of body image dissatisfaction is unclear. Researchers have investigated sociocultural and developmental risk factors; however, the literature needs an integrative etiological model. In 2009, Cheng and Mallinckrodt proposed a dual mediation model, positing that poor-quality parental bonds, via the mechanisms of…

  13. Perceptions of Body Image by Persons with Prader-Willi Syndrome and Their Parents

    ERIC Educational Resources Information Center

    Napolitano, Deborah A.; Zarcone, Jennifer; Nielsen, Sarah; Wang, Hongyue; Caliendo, Jillian Maynard

    2010-01-01

    Prader-Willi syndrome is a genetic disorder characterized by obesity. The Figure Rating Scale (Stunkard, Sorensen, & Schulsinger, 1983) was completed by 43 individuals with this syndrome to determine their level of dissatisfaction with their body. Their parents also completed this scale regarding their child to determine whether they were…

  14. Investigation of meteor shower parent bodies using various metrics

    NASA Astrophysics Data System (ADS)

    Dumitru, B. A.; Birlan, M.; Nedelcu, A.; Popescu, M.

    2016-01-01

    The present knowledge of meteor showers identifies the small bodies of our Solar System as supply sources for meteor streams. Both comets and asteroids are considered as the origin of meteor showers. The new paradigm of "active asteroids" opens up a large field of investigation regarding the relationships between asteroids and meteors. Processes like ejection and disaggregation at impacts, rotational instabilities, electrostatic repulsion, radiation pressure, dehydration stress followed by thermal fractures, sublimation of ices are sources of matter loss from asteroids. Our objective is to find genetic relationships between asteroids and meteor showers using metrics based on orbital elements. For this objective we selected three metrics (Southworth and Hawkins, 1963; Asher et al. 1993, and Jopek, 1993, respectively), the recent MPC database and the more recent IAU meteor shower database. From our analysis, 41 of the meteor showers have probabilities of being produced (or to be fueled) by asteroids. Our sample of asteroids contains more than 1000 objects, all of them belonging to the Near-Earth Asteroid population. The systematic approach performed, based on the physical properties of our sample, reinforced the link between asteroids and their associated meteor shower.

  15. Ar-Ar and I-Xe Ages of Caddo County and Thermal History of IAB Iron Meteorites

    NASA Technical Reports Server (NTRS)

    Bogard, Donald D.; Garrison, Daniel H.; Takeda, Hiroshi

    2005-01-01

    Inclusions in IAB iron meteorites include non-chondritic silicate and those with more primitive chondritic silicate composition. Coarse-grained gabbroic material rich in plagioclase and diopside occurs in the Caddo County IAB iron meteorite and represents a new type of chemically differentiated, extra-terrestrial, andesitic silicate. Other parts of Caddo contain mostly andesitic material. Caddo thus exhibits petrologic characteristics of parent body metamorphism of a chondrite-like parent and inhomogeneous segregation of melts. Proposed IAB formation models include parent body partial melting and fractional crystallization or incomplete differentiation due to internal heat sources, and impact/induced melting and mixing. Benedix et al. prefer a hybrid model whereby the IAB parent body largely melted, then underwent collisional breakup, partial mixing of phases, and reassembly. Most reported 129I- Xe-129 ages of IABs are greater than 4.56 Gyr and a few are greater than or = 4.567 Gyr. These oldest ages exceed the 4.567 Gyr Pb-Pb age of Ca, Al-rich inclusions in primitive meteorites,

  16. Meteoritic basalts. Final report, 1986-1989

    SciTech Connect

    Treiman, A.H.

    1989-10-01

    The objectives were to: explain the abundances of siderophile elements in the SNC meteorite suite, of putative Martian origin; discover the magmatic origins and possibly magma compositions behind the Nakhla meteorite, one of the SNC meteorites; and a re-evaluation of the petrology of Angra dos Reis, a unique meteorite linked to the earliest planetary bodies of the solar nebula. A re-evaluation of its petrography showed that the accepted scenario for its origin, as a cumulate igneous rock, was not consistent with the meteorite's textures (Treiman). More likely is that the meteorite represents a prophyritic igneous rock, originally with magma dominant. Studies of the Nakhla meteorite, of possible Martian origin, although difficult, were successful. It became necessary to reject the basic categorization of Nakhla: that is was a cumulate igneous rock. Detailed studies of the chemical zoning of Nakhlas' minerals, coupled with the failure of experimental studies to yield expected results, forced the conclusion that Nakhla is not a cumulate rock in the usual sense: a rock composed of igneous crystals and intercrystal magma. Study of the siderophile element abundances in the SNC meteorite groups involved trying to find reasonable core formation processes and parameters that would reproduce the observed abundances. Modelling was successful, and delimited a range of models which overlap with those reasonable from geophysical constraints.

  17. Statistical approach to meteoroid shape estimation based on recovered meteorites

    NASA Astrophysics Data System (ADS)

    Vinnikov, V.; Gritsevich, M.; Turchak, L.

    2014-07-01

    Each meteorite sample can provide data on the chemical and physical properties of interplanetary matter. The set of recovered fragments within one meteorite fall can give additional information on the history of its parent asteroid. A reliably estimated meteoroid shape is a valuable input parameter for the atmospheric entry scenario, since the pre-entry mass, terminal meteorite mass, and fireball luminosity are proportional to the pre-entry shape factor of the meteoroid to the power of 3 [1]. We present a statistical approach to the estimation of meteoroid pre-entry shape [2], applied to the detailed data on recovered meteorite fragments. This is a development of our recent study on the fragment mass distribution functions for the Košice meteorite fall [3]. The idea of the shape estimation technique is based on experiments that show that brittle fracturing produces multiple fragments of sizes smaller than or equal to the smallest dimension of the body [2]. Such shattering has fractal properties similar to many other natural phenomena [4]. Thus, this self-similarity for scaling mass sequences can be described by the power law statistical expressions [5]. The finite mass and the number of fragments N are represented via an exponential cutoff for the maximum fragment mass m_U. The undersampling of tiny unrecoverable fragments is handled via an additional constraint on the minimum fragment mass m_L. The complementary cumulative distribution function has the form F( m)={N-j}/{m_j}( {m}/{m_j})^{-β_0}exp( {m-m_j}/{m_U}). The resulting parameters sought (scaling exponent β_0 and mass limits) are computed to fit the empirical fragment mass distribution: S(β_0, j, m_U) = sum_{i=j}^{N}[F(m_i)-{N-j}/{m_j}]^2, m_j = m_L. The scaling exponent correlates with the dimensionless shape parameter d [2]: 0.13d^2-0.21d+1.1-β=0, which, in turn, is expressed via the ratio of the linear dimensions a, b, c of the shattering body [2]: d = 1+2(ab+ac+bc)(a^2+b^2+c^2)^{-1}. We apply the

  18. Fossils of Cyanobacteria in CI1 Carbonaceous Meteorites: Implications to Life on Comets, Europa, and Enceladus

    NASA Astrophysics Data System (ADS)

    Hoover, Richard B.

    studies have led to the conclusion that the filaments found in the CI1 carbonaceous meteorites are indigenous fossils rather than modern terrestrial biological contaminants that entered the meteorites after arrival on Earth. The δ13C and D/H content of amino acids and other organics found in these stones are shown to be consistent with the interpretation that comets represent the parent bodies of the CI1 carbonaceous meteorites. The implications of the detection of fossils of cyanobacteria in the CI1 meteorites to the possibility of life on comets, Europa and Enceladus are discussed.

  19. Palladium-silver chronology of IAB iron meteorites

    NASA Astrophysics Data System (ADS)

    Theis, K. J.; Schönbächler, M.; Benedix, G. K.; Rehkämper, M.; Andreasen, R.; Davies, C.

    2013-01-01

    The extinct 107Pd-107Ag decay system (half-life ˜6.5 Ma) is a useful chronometer to constrain the thermal evolution of the IAB parent body. To this end, Pd/Ag concentrations and the Ag isotope compositions of metals separated from 6 different IAB iron meteorites were determined. The samples show ɛ107Ag variations between +0.1 and +15.8 with 108Pd/109Ag ratios between 38 and 200. The data can be divided into two groups based on their petrology, each defining an isochron: a graphite and troilite rich inclusion bearing group (A), with the IAB meteorites Toluca, Odessa and Canyon Diablo and a more silicate rich group (B), which includes Campo Del Cielo, Caddo County and Goose Lake. Using the initial abundance of 107Pd derived from carbonaceous chondrites, the corresponding age for the group (A) is 18.7 (+3.6/-5.0) Ma after the start of the solar system and 14.9 (+2.5/-4.9) Ma for the group (B). This suggests that the last thermal event to reach high enough temperatures to melt metal on the IAB parent body occurred within the first 15 Ma of our solar system.

  20. Cosmogenic effects on Cu isotopes in IVB iron meteorites

    NASA Astrophysics Data System (ADS)

    Chen, Heng; Moynier, Frédéric; Humayun, Munir; Bishop, M. Cole; Williams, Jeffrey T.

    2016-06-01

    We measured Cu isotope compositions of 12 out of the 14 known IVB iron meteorites. Our results show that IVB iron meteorites display a very large range of δ65Cu values (-5.84‰ < δ65Cu < -0.24‰; defined as per mil deviation of the 65Cu/63Cu ratio from the NIST-976 standard). These Cu isotopic data display clear correlations with W, Pt, and Os isotope ratios, which are very sensitive to secondary neutron capture due to galactic cosmic ray (GCR) irradiation. This demonstrates that δ65Cu in IVB irons is majorly modified by neutron capture by the reaction 62Ni(n,γ)63Ni followed by beta decay to 63Cu. Using correlations with Pt and Os neutron dosimeters, we calculated a pre-exposure δ65Cu of -0.3 ± 0.8‰ (95% conf.) of IVB irons that agrees well with the Cu isotopic compositions of other iron meteorite groups and falls within the range of chondrites. This shows that the volatile depletion of the IVB parent body is not due to evaporation that should have enriched IVB irons in the heavy Cu isotopes.

  1. Meteorite Falls in Morocco

    NASA Astrophysics Data System (ADS)

    Chennaoui Aoudjehane, H.

    2016-08-01

    The number of meteorite falls reported in Morocco since 2000 is highest than any other place compared to the other countries in the world, that call into question the efficiency of the randomly meteorite falls on Earth.

  2. Searching for Meteorites

    NASA Video Gallery

    This lesson combines a series of activities to provide students with an understanding of how meteorites can unlock answers to the early history of the solar system and how meteorites and their big ...

  3. "BodyWorks": A Parent-Focused Program to Promote Healthful Eating and Physical Activity for Children and Adolescents

    ERIC Educational Resources Information Center

    Borden, Valerie Melino; Labiner-Wolfe, Judith; Blake, Susan M.; Marr, Amanda; Rowe, Jonelle; Wasserman, Jill

    2012-01-01

    The "BodyWorks" program was designed to help parents improve family eating and activity behaviors. "BodyWorks" was associated with significant gains in parents' knowledge about nutrition and activity, and greater self-efficacy to set family nutrition goals, plan physical activities, and change eating habits. (Contains 1 table.)

  4. A search for H-chondritic chromite grains in sediments that formed immediately after the breakup of the L-chondrite parent body 470 Ma ago

    NASA Astrophysics Data System (ADS)

    Heck, Philipp R.; Schmitz, Birger; Rout, Surya S.; Tenner, Travis; Villalon, Krysten; Cronholm, Anders; Terfelt, Fredrik; Kita, Noriko T.

    2016-03-01

    A large abundance of L-chondritic material, mainly in the form of fossil meteorites and chromite grains from micrometeorites, has been found in mid-Ordovician 470 Ma old sediments globally. The material has been determined to be ejecta from the L chondrite parent body breakup event, a major collision in the asteroid belt 470 Ma ago. In this study we search the same sediments for H-chondritic chromite grains in order to improve our understanding of the extraterrestrial flux to Earth after the asteroid breakup event. We have used SIMS in conjunction with quantitative SEM/EDS to determine the three oxygen isotopic and elemental compositions, respectively, of a total of 120 randomly selected, sediment-dispersed extraterrestrial chromite grains mainly representing micrometeorites from 470 Ma old post-breakup limestone from the Thorsberg quarry in Sweden and the Lynna River site in Russia. We show that 99% or more of the grains are L-chondritic, whereas the H-chondritic fraction is 1% or less. The L-/H-chondrite ratio after the breakup thus was >99 compared to 1.1 in today's meteoritic flux. This represents independent evidence, in agreement with previous estimates based on sediment-dispersed extraterrestrial chromite grain abundances and sedimentation rates, of a two orders of magnitude higher post-breakup flux of L-chondritic material in the micrometeorite fraction. Finally, we confirm the usefulness of three oxygen isotopic SIMS analyses of individual extraterrestrial chromite grains for classification of equilibrated ordinary chondrites. The H- and L-chondritic chromites differ both in their three oxygen isotopic and elemental compositions, but there is some overlap between the groups. In chromite, TiO2 is the oxide most resistant to diagenesis, and the combined application of TiO2 and oxygen three-isotope analysis can resolve uncertainties arising from the compositional overlaps.

  5. Microfossils in CI and CO Carbonaceous Meteorites

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.; Rozanov, Alexei Y.; Jerman, Gregory; Costen, James

    2003-01-01

    Secondary and backscatter electron images and x-ray spectral data of selected CI (Alais, Orgueil, and Tagish Lake) and CO3 (Rainbow and Dar a1 Gani 749) carbonaceous meteorites have recently been obtained using Field Emission and Environmental Scanning Electron Microscopes These studies indicate the presence of a large assemblage of biomarkers and complex lithified and carbonized remains of bodies that we interpret as indigenous microfossils. We discuss the meteorites, provide images of many of the biogenic forms found embedded in the freshly fractured meteorite surfaces.

  6. Weathering of stony meteorites in Antarctica

    NASA Technical Reports Server (NTRS)

    Gooding, J. L.

    1986-01-01

    Weathering produces undesirable physical, chemical, and isotopic changes that might disturb the records of cosmochemical evolution that are sought in meteorites. Meteorites are physically disintegrated by crack propagation phenomena, including ice riving and secondary mineral riving, and are probably abraded by wind that is laden with ice crystals or dust particles. Chemical weathering proceeds by oxidation, hydration, carbonation, and solution and produces a variety of secondary minerals and mineraloids. Differential weathering under freezing conditions is discussed, as well as, the mineralogy of weathering products. Furthermore, the use of Antarctic alteration of meteorites could be used as an excellent analog for weathering on Mars or on cometary bodies.

  7. Magnetic minerals of the chelyabinsk meteorite

    NASA Astrophysics Data System (ADS)

    Markov, G. P.; Pecherskii, D. M.; Tsel'movich, V. A.

    2015-09-01

    Eight samples of the Chelyabinsk meteorite were studied using thermomagnetic and electron microprobe analyses; the hysteresis loop characteristics were also measured. The main magnetic minerals of the meteorite are represented by two groups of Fe-Ni alloys (native Fe minerals) with various concentrations of nickel and iron sulfides. A small number of magnetite balls were found. They are probably formed due to oxidation of troilite and other Fe sulfides as a result of melting of the meteorite due to passage through the Earth's atmosphere. The observed effect of the primary hysteresis loop constriction is probably connected with prolonged annealing of a celestial body before its transition into the meteoroid state.

  8. The formation of IIE iron meteorites investigated by the chondrule-bearing Mont Dieu meteorite

    NASA Astrophysics Data System (ADS)

    van Roosbroek, N.; Debaille, V.; Pittarello, L.; Goderis, S.; Humayun, M.; Hecht, L.; Jourdan, F.; Spicuzza, M. J.; Vanhaecke, F.; Claeys, Ph.

    2015-07-01

    A 435 kg piece of the Mont Dieu iron meteorite (MD) contains cm-sized silicate inclusions. Based on the concentration of Ni, Ga, Ge, and Ir (8.59 ± 0.32 wt%, 25.4 ± 0.9 ppm, 61 ± 2 ppm, 7.1 ± 0.4 ppm, respectively) in the metal host, this piece can be classified as a IIE nonmagmatic iron. The silicate inclusions possess a chondritic mineralogy and relict chondrules occur throughout the inclusions. Major element analysis, oxygen isotopic analysis (Δ17O = 0.71 ± 0.02‰), and mean Fa and Fs molar contents (Fa15.7 ± 0.4 and Fs14.4 ± 0.5) indicate that MD originated as an H chondrite. Because of strong similarities with Netschaëvo IIE, MD can be classified in the most primitive subgroup of the IIE sequence. 40Ar/39Ar ages of 4536 ± 59 Ma and 4494 ± 95 Ma obtained on pyroxene and plagioclase inclusions show that MD belongs to the old (~4.5 Ga) group of IIE iron meteorites and that it has not been perturbed by any subsequent heating event following its formation. The primitive character of MD sheds light on the nature of its formation process, its thermal history, and the evolution of its parent body.

  9. Evidence for 2009 WN25 being the parent body of the November i-Draconids (NID)

    NASA Astrophysics Data System (ADS)

    Micheli, Marco; Tholen, David J.; Jenniskens, Peter

    2016-03-01

    In this work we propose the Amor-type asteroid 2009 WN25 as the likely progenitor of the November i-Draconids (NID, IAU#392), a recently detected weak annual meteoroid stream. We first describe our recovery and follow-up effort to obtain timely ground based astrometry with large aperture telescopes, and ensure that 2009 WN25 would not become lost. We then discuss the possible parent-stream association, using its updated orbit to model the ejection of dust particles from the surface of the parent body and match the observed properties of the stream.

  10. Critical Elements of a School Report to Parents on Body Mass Index

    PubMed Central

    Linchey, Jennifer K.; Madsen, Kristine A.

    2015-01-01

    School-based body mass index (BMI) screening and reporting could have a positive impact on student health, but best practices for writing a report are unknown. Building on previous qualitative work, 8 focus groups were conducted with a diverse group of California parents (n = 79) to elicit feedback on report content and design. Results indicate that parents want a visually appealing, picture-heavy report that clearly defines BMI, avoids stigmatizing language, and includes recommendations for appropriate actions whole families can take. Next steps involve using the final report in a statewide, randomized trial to determine the effectiveness of school-based BMI screening and reporting in reducing childhood obesity. PMID:26312381

  11. Adolescent-parent interactions and communication preferences regarding body weight and weight management: a qualitative study

    PubMed Central

    2010-01-01

    Background This study aimed to canvass the nature of adolescent-parent interactions about weight, particularly overweight, and to explore ideas of how to foster supportive discussions regarding weight, both in the home and with family doctors. Methods A market research company was contracted to recruit and conduct a series of separate focus groups with adolescents and unrelated parents of adolescents from low-middle socio-economic areas in Sydney and a regional centre, Australia. Group discussions were audio recorded, transcribed, and then a qualitative content analysis of the data was performed. Results Nine focus groups were conducted; two were held with girls (n = 13), three with boys (n = 18), and four with parents (20 mothers, 12 fathers). Adolescent and parent descriptions of weight-related interactions could be classified into three distinct approaches: indirect/cautious (i.e. focus on eating or physical activity behaviors without discussing weight specifically); direct/open (i.e. body weight was discussed); and never/rarely discussing the subject. Indirect approaches were described most frequently by both adolescents and parents and were generally preferred over direct approaches. Parents and adolescents were circumspect but generally supportive of the potential role for family doctors to monitor and discuss adolescent weight status. Conclusions These findings have implications for developing acceptable messages for adolescent and family overweight prevention and treatment interventions. PMID:20205918

  12. 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.

  13. Neutron capture on Pt isotopes in iron meteorites and the Hf-W chronology of core formation in planetesimals

    NASA Astrophysics Data System (ADS)

    Kruijer, Thomas S.; Fischer-Gödde, Mario; Kleine, Thorsten; Sprung, Peter; Leya, Ingo; Wieler, Rainer

    2013-01-01

    The short-lived 182Hf-182W isotope system can provide powerful constraints on the timescales of planetary core formation, but its application to iron meteorites is hampered by neutron capture reactions on W isotopes resulting from exposure to galactic cosmic rays. Here we show that Pt isotopes in magmatic iron meteorites are also affected by capture of (epi)thermal neutrons and that the Pt isotope variations are correlated with variations in 182W/184W. This makes Pt isotopes a sensitive neutron dosimeter for correcting cosmic ray-induced W isotope shifts. The pre-exposure 182W/184W derived from the Pt-W isotope correlations of the IID, IVA and IVB iron meteorites are higher than most previous estimates and are more radiogenic than the initial 182W/184W of Ca-Al-rich inclusions (CAI). The Hf-W model ages for core formation range from +1.6±1.0 million years (Ma; for the IVA irons) to +2.7±1.3 Ma after CAI formation (for the IID irons), indicating that there was a time gap of at least ˜1 Ma between CAI formation and metal segregation in the parent bodies of some iron meteorites. From the Hf-W ages a time limit of <1.5-2 Ma after CAI formation can be inferred for the accretion of the IID, IVA and IVB iron meteorite parent bodies, consistent with earlier conclusions that the accretion of differentiated planetesimals predated that of most chondrite parent bodies.

  14. Heterogeneous growth of meteorites and planets, especially the earth and moon

    NASA Technical Reports Server (NTRS)

    Smith, J. V.

    1982-01-01

    It is pointed out that enough information remains in meteorites to show that the solar nebula was chemically inhomogeneous, and that it did not develop under physical and chemical equilibrium. It is found that the earth is not in chemical equilibrium, and that it still retains vestiges of its heterogeneous growth in spite of prolonged convection and volcanism. The present investigation has the aim to unify simple ideas into a comprehensive, complex scheme for heterogeneous growth of the planets and parent bodies of meteorites. A scheme is considered for the conversion of dust and gas in the solar nebula into the present population of bodies. Attention is given to possible processes for the growth and development of planetesimals from dust via clouds, the major episodes in the development of the solar system, the relation of meteorites to a solar nebula with monotonic variation of temperature and oxidation state, the significance of meteorite properties, the composition of the inner planets, and the development of the earth.

  15. On the irradiation history and origin of gas-rich meteorites

    NASA Technical Reports Server (NTRS)

    Rajan, R. S.

    1974-01-01

    Transmission electron microscope study of the track density gradients and irradiation geometries of track-rich grains and chondrules in sections of Fayetteville and Kapoeta, and in sections of lunar breccias and grains from lunar soil. A substantial fraction (50 to 90%) of the meteoritic track-rich grains and chondrules show evidence of having been irradiated anisotropically in their different faces, as would be expected for irradiation on the surface of a parent body. The observations thus support the hypothesis that the irradiation of these grains and chondrules took place on the regoliths of asteroidal-sized bodies. Measurements of steepest track density gradients indicate that, while there are finite differences between spectra exhibited by individual gas-rich meteorites, the average solar flare spectral shapes have been similar over the last 4 b.y. or so.

  16. Disentangling the associations between parental BMI and offspring body composition using the four‐component model

    PubMed Central

    Grijalva‐Eternod, Carlos; Cortina‐Borja, Mario; Williams, Jane; Fewtrell, Mary; Wells, Jonathan

    2016-01-01

    ABSTRACT Objectives This study sets out to investigate the intergenerational associations between the body mass index (BMI) of parents and the body composition of their offspring. Methods The cross‐sectional data were analyzed for 511 parent–offspring trios from London and south‐east England. The offspring were aged 5–21 years. Parental BMI was obtained by recall and offspring fat mass and lean mass were obtained using the four‐component model. Multivariable regression analysis, with multiple imputation for missing paternal values was used. Sensitivity analyses for levels of non‐paternity were conducted. Results A positive association was seen between parental BMI and offspring BMI, fat mass index (FMI), and lean mass index (LMI). The mother's BMI was positively associated with the BMI, FMI, and LMI z‐scores of both daughters and sons and of a similar magnitude for both sexes. The father's BMI showed similar associations to the mother's BMI, with his son's BMI, FMI, and LMI z‐scores, but no association with his daughter. Sensitivity tests for non‐paternity showed that maternal coefficients remained greater than paternal coefficients throughout but there was no statistical difference at greater levels of non‐paternity. Conclusions We found variable associations between parental BMI and offspring body composition. Associations were generally stronger for maternal than paternal BMI, and paternal associations appeared to differ between sons and daughters. In this cohort, the mother's BMI was statistically significantly associated with her child's body composition but the father's BMI was only associated with the body composition of his sons. Am. J. Hum. Biol. 28:524–533, 2016. © 2016 The Authors American Journal of Human Biology Published by Wiley Periodicals, Inc. PMID:26848813

  17. Parental bonds, attachment anxiety, media susceptibility, and body dissatisfaction: a mediation model.

    PubMed

    Patton, Sarah C; Beaujean, A Alexander; Benedict, Helen E

    2014-08-01

    The developmental trajectory of body image dissatisfaction is unclear. Researchers have investigated sociocultural and developmental risk factors; however, the literature needs an integrative etiological model. In 2009, Cheng and Mallinckrodt proposed a dual mediation model, positing that poor-quality parental bonds, via the mechanisms of heightening romantic attachment anxiety and thin-ideal media internalization, increases body dissatisfaction. We tested 2 versions of this model, including an alternate model featuring attachment anxiety in close friendships. We recruited females ages 12-24, primarily from a mid-sized private religious university, to complete self-report measures. The participant sample was ethnically diverse, with approximately 40% endorsing minority status. Results showed that mother care and father care were negatively linked to friendship attachment anxiety and romantic attachment anxiety. Friendship and romantic attachment anxiety were positively linked to media susceptibility. Media susceptibility was positively linked to body image dissatisfaction. Mother care and father care were negatively, indirectly linked to body image dissatisfaction through the mediators of friendship attachment anxiety and media susceptibility. Mother care made a significant, albeit small, contribution to body image dissatisfaction after controlling for other variables. Overall, findings suggest that adverse parent-child relational factors may indirectly elevate body dissatisfaction, operating through attachment anxiety and susceptibility to sociocultural pressures.

  18. Origin of felsic achondrites Graves Nunataks 06128 and 06129, and ultramafic brachinites and brachinite-like achondrites by partial melting of volatile-rich primitive parent bodies

    NASA Astrophysics Data System (ADS)

    Day, James M. D.; Walker, Richard J.; Ash, Richard D.; Liu, Yang; Rumble, Douglas; Irving, Anthony J.; Goodrich, Cyrena A.; Tait, Kimberly; McDonough, William F.; Taylor, Lawrence A.

    2012-03-01

    New major- and trace-element abundances, highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, Re) abundances, and oxygen and rhenium-osmium isotope data are reported for oligoclase-rich meteorites Graves Nunataks 06128 and 06129 (GRA 06128/9), six brachinites (Brachina; Elephant Morraine 99402/7; Northwest Africa (NWA) 1500; NWA 3151; NWA 4872; NWA 4882) and three olivine-rich achondrites, which are referred to here as brachinite-like achondrites (NWA 5400; NWA 6077; Zag (b)). GRA 06128/9 represent examples of felsic and highly-sodic melt products from an asteroid that may provide a differentiation complement to brachinites and/or brachinite-like achondrites. The new data, together with our petrological observations, are consistent with derivation of GRA 06128/9, brachinites and the three brachinite-like achondrites from nominally volatile-rich and oxidised 'chondritic' precursor sources within their respective parent bodies. Furthermore, the range of Δ17O values (˜0‰ to -0.3‰) among the meteorites indicates generation from isotopically heterogeneous sources that never completely melted, or isotopically homogenised. It is possible to generate major- and trace-element compositions similar to brachinites and the three studied brachinite-like achondrites as residues of moderate degrees (13-30%) of partial melting of primitive chondritic sources. This process was coupled with inefficient removal of silica-saturated, high Fe/Mg felsic melts with compositions similar to GRA 06128/9. Melting of the parent bodies of GRA 06128/9, brachinites and brachinite-like achondrites halted well before extensive differentiation, possibly due to the exhaustion of the short-lived radionuclide 26Al by felsic melt segregation. This mechanism provides a potential explanation for the cessation of run-away melting in asteroids to preserve achondrites such as GRA 06128/9, brachinites, brachinite-like achondrites, acapulcoite-lodranites, ureilites and aubrites. Moderate degrees of

  19. Classification and radiative-transfer modeling of meteorite spectra

    NASA Astrophysics Data System (ADS)

    Pentikäinen, H.; Penttilä, A.; Peltoniemi, J.; Muinonen, K.

    2014-07-01

    The interpretation of asteroid spectra is closely tied to surface structure and composition. Asteroid surfaces are usually assumed to be covered with a regolith, which is a mixture of mineral grains ranging from micrometers to centimeters in size. The inverse problem of deducing the characteristics of the grains from the scattering of light (e.g., using photometric and polarimetric observations) is difficult. Meteorite spectroscopy can be a valuable alternative source of information considering that unweathered meteoritic ''falls'' are almost pristine samples of their parent bodies. Reflectance spectra of 18 different meteorite samples were measured with the Finnish Geodetic Institute Field Goniospectrometer (FIGIFIGO) covering a wavelength range of 450--2250 nm [1,2]. The measurements expand the database of reflectance spectra obtained by Paton et al. [3] and Gaffey [4]. Principal Component Analysis (PCA) performed on the spectra indicates a separation of the undifferentiated ordinary chondrites and the differentiated achondrites. The principal components also suggest a discrimination between the spectra of ordinary chondrites with petrologic grades 5 and 6. The distinction is not present when the data are supplemented with the spectra from the two other data sets obtained with differing measuring techniques. To further investigate the different classifications, the PCA is implemented with selected spectral features contrary to the previous analyses, which encompassed the complete spectra. Single-scattering albedos for meteoritic fundamental scatterers were derived with a Monte Carlo radiative-transfer model [1]. In the derivation, realistic scattering phase functions were utilized. The functions were obtained by fitting triple Henyey-Greenstein functions to the measured scattering phase functions of olivine powder for two different size distributions [5,6]. The simulated reflectances for different scattering phase functions were matched to the measured meteorite

  20. A model composition for Mars derived from the oxygen isotopic ratios of martian/SNC meteorites. [Abstract only

    NASA Technical Reports Server (NTRS)

    Delaney, J. S.

    1994-01-01

    Oxygen is the most abundant element in most meteorites, yet the ratios of its isotopes are seldom used to constrain the compositional history of achondrites. The two major achondrite groups have O isotope signatures that differ from any plausible chondritic precursors and lie between the ordinary and carbonaceous chondrite domains. If the assumption is made that the present global sampling of chondritic meteorites reflects the variability of O reservoirs at the time of planetessimal/planet aggregation in the early nebula, then the O in these groups must reflect mixing between known chondritic reservoirs. This approach, in combination with constraints based on Fe-Mn-Mg systematics, has been used previously to model the composition of the basaltic achondrite parent body (BAP) and provides a model precursor composition that is generally consistent with previous eucrite parent body (EPB) estimates. The same approach is applied to Mars exploiting the assumption that the SNC and related meteorites sample the martian lithosphere. Model planet and planetesimal compositions can be derived by mixing of known chondritic components using O isotope ratios as the fundamental compositional constraint. The major- and minor-element composition for Mars derived here and that derived previously for the basaltic achondrite parent body are, in many respects, compatible with model compositions generated using completely independent constraints. The role of volatile elements and alkalis in particular remains a major difficulty in applying such models.

  1. New showers from parent body search across several video meteor databases

    NASA Astrophysics Data System (ADS)

    Šegon, Damir; Gural, Peter; Andreić, Željko; Skokić, Ivica; Korlević, Korado; Vida, Denis; Novoselnik, Filip

    2014-04-01

    This work was initiated by utilizing the latest complete set of both comets and NEOs downloaded from the JPL small-body database search engine. Rather than search for clustering within a single given database of meteor orbits, the method employed herein is to use all the known parent bodies with their individual orbital elements as the starting point, and find statistically significant associations across a variety of meteor databases cmns3-sonotaco,cmns3-cmnsdb. Fifteen new showers possibly related to a comet or a NEO were found.

  2. No evidence for a decrease of nuclear decay rates with increasing heliocentric distance based on radiochronology of meteorites

    NASA Astrophysics Data System (ADS)

    Meier, Matthias M. M.; Wieler, Rainer

    2014-03-01

    It has been argued that the decay rates of several radioactive nuclides are slightly lower at Earth's aphelion than at perihelion, and that this effect might depend on heliocentric distance. It might then be expected that nuclear decay rates be considerably lower at larger distances from the sun, e.g., in the asteroid belt at 2-3 AU from where most meteorites originate. If so, ages of meteorites obtained by analyses of radioactive nuclides and their stable daughter isotopes might be in error, since these ages are based on decay rates determined on Earth. Here we evaluate whether the large data base on nuclear cosmochronology offers any hint for discrepancies which might be due to radially variable decay rates. Chlorine-36 (t1/2 = 301,000 a) is produced in meteorites by interactions with cosmic rays and is the nuclide for which a decay rate dependence from heliocentric distance has been proposed, which, in principle, can be tested with our approach and the current data base. We show that compilations of 36Cl concentrations measured in meteorites offer no support for a spatially variable 36Cl decay rate. For very short-lived cosmic-ray produced radionuclides (half-lives < 10-100 days), the concentration should be different for meteorites hitting the Earth on the incoming vs. outgoing part of their orbit. However, the current data base of very short-lived radionuclides in freshly fallen meteorites is far from sufficient to deduce solid constraints. Constraints on the age of the Earth and the oldest meteorite phases obtained by the U-Pb dating technique give no hints for radially variable decay rates of the α-decaying nuclides 235U or 238U. Similarly, some of the oldest phases in meteorites have U-Pb ages whose differences agree almost perfectly with respective age differences obtained with "short-lived" radionuclides present in the early solar system, again indicating no variability of uranium decay rates in different meteorite parent bodies in the asteroid belt

  3. Early aqueous activity on the ordinary and carbonaceous chondrite parent bodies recorded by fayalite

    DOE PAGES

    Doyle, Patricia M.; Jogo, Kaori; Nagashima, Kazuhide; Krot, Alexander N.; Wakita, Shigeru; Ciesla, Fred J.; Hutcheon, Ian D.

    2015-06-23

    Here, chronology of aqueous activity on chondrite parent bodies constrains their accretion times and thermal histories. Radiometric 53Mn–53Cr dating has been successfully applied to aqueously formed carbonates in CM carbonaceous chondrites. Owing to the absence of carbonates in ordinary (H, L and LL), and CV and CO carbonaceous chondrites, and the lack of proper standards, there are no reliable ages of aqueous activity on their parent bodies. Here we report the first 53Mn–53Cr ages of aqueously formed fayalite in the L3 chondrite Elephant Moraine 90161 as 2.4 +1.8-1.3 Myr after calcium–aluminium-rich inclusions (CAIs), the oldest Solar System solids. In addition,more » measurements using our synthesized fayalite standard show that fayalite in the CV3 chondrite Asuka 881317 and CO3-like chondrite MacAlpine Hills 88107 formed and 4.2+0.8-0.7 Myr after CAIs, respectively. Thermal modelling, combined with the inferred conditions (temperature and water/rock ratio) and 53Mn–53Cr ages of aqueous alteration, suggests accretion of the L, CV and CO parent bodies ~1.8–2.5 Myr after CAIs.« less

  4. Early aqueous activity on the ordinary and carbonaceous chondrite parent bodies recorded by fayalite

    NASA Astrophysics Data System (ADS)

    Doyle, Patricia M.; Jogo, Kaori; Nagashima, Kazuhide; Krot, Alexander N.; Wakita, Shigeru; Ciesla, Fred J.; Hutcheon, Ian D.

    2015-06-01

    Chronology of aqueous activity on chondrite parent bodies constrains their accretion times and thermal histories. Radiometric 53Mn-53Cr dating has been successfully applied to aqueously formed carbonates in CM carbonaceous chondrites. Owing to the absence of carbonates in ordinary (H, L and LL), and CV and CO carbonaceous chondrites, and the lack of proper standards, there are no reliable ages of aqueous activity on their parent bodies. Here we report the first 53Mn-53Cr ages of aqueously formed fayalite in the L3 chondrite Elephant Moraine 90161 as Myr after calcium-aluminium-rich inclusions (CAIs), the oldest Solar System solids. In addition, measurements using our synthesized fayalite standard show that fayalite in the CV3 chondrite Asuka 881317 and CO3-like chondrite MacAlpine Hills 88107 formed and Myr after CAIs, respectively. Thermal modelling, combined with the inferred conditions (temperature and water/rock ratio) and 53Mn-53Cr ages of aqueous alteration, suggests accretion of the L, CV and CO parent bodies ~1.8-2.5 Myr after CAIs.

  5. Early aqueous activity on the ordinary and carbonaceous chondrite parent bodies recorded by fayalite.

    PubMed

    Doyle, Patricia M; Jogo, Kaori; Nagashima, Kazuhide; Krot, Alexander N; Wakita, Shigeru; Ciesla, Fred J; Hutcheon, Ian D

    2015-01-01

    Chronology of aqueous activity on chondrite parent bodies constrains their accretion times and thermal histories. Radiometric (53)Mn-(53)Cr dating has been successfully applied to aqueously formed carbonates in CM carbonaceous chondrites. Owing to the absence of carbonates in ordinary (H, L and LL), and CV and CO carbonaceous chondrites, and the lack of proper standards, there are no reliable ages of aqueous activity on their parent bodies. Here we report the first (53)Mn-(53)Cr ages of aqueously formed fayalite in the L3 chondrite Elephant Moraine 90161 as Myr after calcium-aluminium-rich inclusions (CAIs), the oldest Solar System solids. In addition, measurements using our synthesized fayalite standard show that fayalite in the CV3 chondrite Asuka 881317 and CO3-like chondrite MacAlpine Hills 88107 formed and Myr after CAIs, respectively. Thermal modelling, combined with the inferred conditions (temperature and water/rock ratio) and (53)Mn-(53)Cr ages of aqueous alteration, suggests accretion of the L, CV and CO parent bodies ∼1.8-2.5 Myr after CAIs. PMID:26100451

  6. Early aqueous activity on the ordinary and carbonaceous chondrite parent bodies recorded by fayalite

    SciTech Connect

    Doyle, Patricia M.; Jogo, Kaori; Nagashima, Kazuhide; Krot, Alexander N.; Wakita, Shigeru; Ciesla, Fred J.; Hutcheon, Ian D.

    2015-06-23

    Here, chronology of aqueous activity on chondrite parent bodies constrains their accretion times and thermal histories. Radiometric 53Mn–53Cr dating has been successfully applied to aqueously formed carbonates in CM carbonaceous chondrites. Owing to the absence of carbonates in ordinary (H, L and LL), and CV and CO carbonaceous chondrites, and the lack of proper standards, there are no reliable ages of aqueous activity on their parent bodies. Here we report the first 53Mn–53Cr ages of aqueously formed fayalite in the L3 chondrite Elephant Moraine 90161 as 2.4 +1.8-1.3 Myr after calcium–aluminium-rich inclusions (CAIs), the oldest Solar System solids. In addition, measurements using our synthesized fayalite standard show that fayalite in the CV3 chondrite Asuka 881317 and CO3-like chondrite MacAlpine Hills 88107 formed and 4.2+0.8-0.7 Myr after CAIs, respectively. Thermal modelling, combined with the inferred conditions (temperature and water/rock ratio) and 53Mn–53Cr ages of aqueous alteration, suggests accretion of the L, CV and CO parent bodies ~1.8–2.5 Myr after CAIs.

  7. Puna Dacite: Likely Temperature, Viscosity, Origin, Size, and Parent Body Nature

    NASA Astrophysics Data System (ADS)

    Marsh, B.; Teplow, W.; Reagan, M.; Sims, K.

    2008-12-01

    This is very likely the first accidental encounter of an in situ live magma within Earth. The importance of this occurrence to the possible ongoing interrogation of an active, docile magma cannot be overemphasized. Here we report on inferences on the nature of the magma and its relation to a parent basaltic body. The Glass: In oil the glass is colorless with 5-8 % euhedral, nonquench crystals of plagioclase, Fe-Ti oxide, orthopyroxene, and apatite. There is no vesiculation and the glass is unstructured except for patches of perhaps incipient spherulite and swirls, which may reflect drilling shear and quenching. Temperature: The temperature is inferred first using the bulk glass composition and matching the visually estimated crystallinity to that computed by MELTS, giving a temperature of 1050 C. Second, from a likely basaltic parent composition (1955 basalt) and matching the glass composition to the residual melt from protracted crystallization in MELTS, also gives a temperature of 1050 C. Comparing the dacite to the observed compositions of interstitial melts from the lava lakes, suggests a slightly higher temperature of 1065 C, reflecting the different parent basalt. One atm melting experiments confirm the former T. Magma Viscosity: The flow up the drill hole (25.88 cm diameter) can be used to estimate viscosity by calculating the time necessary for melt of a given viscosity to flow under a given pressure gradient a given distance up the drill hole. The melt flowed upward approximately 5.5.m in a few minutes. The most elusive part of the calculation involves estimating the pressure gradient driving the flow. The lithostatic load based on the depth (~2.54 km) is about 0.65 kb, which is assumed to act over a characteristic distance of about 2 m (lens size) to give a characteristic pressure gradient. Pipe flow yields a characteristic viscosity of 3.8 x 107 p. An independent calculation from MELTS using only melt composition, temperature, water content (zero), and

  8. UV photolysis, organic molecules in young disks, and the origin of meteoritic amino acids

    NASA Astrophysics Data System (ADS)

    Throop, Henry B.

    2011-04-01

    The origin of complex organic molecules such as amino acids and their precursors found in meteorites and comets is unknown. Previous studies have accounted for the complex organic inventory of the Solar System by aqueous chemistry on warm meteoritic parent bodies, or by accretion of organics formed in the interstellar medium. This paper proposes a third possibility: that complex organics were created in situ by ultraviolet light from nearby O/B stars irradiating ices already in the Sun's protoplanetary disk. If the Sun was born in a dense cluster near UV-bright stars, the flux hitting the disk from external stars could be many orders of magnitude higher than that from the Sun alone. Such photolysis of ices in the laboratory can rapidly produce amino acid precursors and other complex organic molecules. I present a simple model coupling grain growth and UV exposure in a young circumstellar disk. It is shown that the production may be sufficient to create the Solar System's entire complex organic inventory within 10 6 yr. Subsequent aqueous alteration on meteoritic parent bodies is not ruled out.

  9. Mineralogy of HED Meteorites Using the Modified Gaussian Model

    NASA Astrophysics Data System (ADS)

    Canas, Lina; Duffard, René; Seixas, Teresa

    2008-06-01

    The correlation between specific meteorites and asteroids is a long-standing problem. The best-known correlation seems to be the HED-Vesta, although several problems still remain to be solved. We report the spectral reflectance analysis (0.4-2.5 μm) of a set of HED meteorites, taken from the RELAB database and three V-type asteroids, taken from MIT-UH-IRTF Joint Campaign for NEO Reconnaissance. We used the Modified Gaussian Model to fit the spectra to a series of overlapping, modified Gaussian absorptions. The fitted individual bands are validated against established laboratory calibrations. With spectral resolution extending to the near-infrared, we are able to resolve the presence of both high-calcium pyroxene (HCP) and low-calcium pyroxene (LCP) and, thus, use the HCP/(HCP + LCP) ratios to remotely trace igneous processing on the parent asteroids. A search of this mineral provides a useful probe of differentiation. The high HCP/(HCP + LCP) ratios found require extensive differentiation of these asteroids and/or their primordial parent body. The degree of melting obtained for the eucrites, using the former ratio, is comparable with that obtained for all V-type asteroids here analyzed, suggesting a comparable geologic history.

  10. Weight-Related Health Behaviors and Body Mass: Associations between Young Adults and Their Parents, Moderated by Parental Authority

    ERIC Educational Resources Information Center

    Niemeier, Brandi S.; Hektner, Joel M.

    2012-01-01

    Background: Parents' behaviors could contribute to the development of their children's weight-related health behaviors. Purpose: Relationships of young adults' (N = 151) and their parents' weight-related behaviors were examined along with parental authority styles. Methods: Questionnaires were completed by young adults and their parents.…

  11. Meteoritic Constraints on Models of the Solar Nebula: The Abundances of Moderately Volatile Elements

    NASA Technical Reports Server (NTRS)

    Cassen, Patrick; Cuzzi, Jeff (Technical Monitor)

    1994-01-01

    formation of the chondrite parent bodies and the planets.

  12. Scale-Dependent Measurements of Meteorite Strength and Fragmentation: Tamdakht (H5) and Allende (CV3)

    NASA Astrophysics Data System (ADS)

    Cotto-Figueroa, Desireé; Asphaug, Erik; Garvie, Laurence; Morris, Melissa; Rai, Ashwin; Chattopadhyay, Aditi; Chawla, Nikhilesh

    2015-11-01

    Meteorites are pieces of natural space debris, which have survived ejection from their parent bodies and passage through the Earth’s atmosphere. As such, they provide a unique opportunity to study the fundamental physical and mechanical properties of early Solar System materials. But to date, few direct studies of physical properties have been conducted on meteoritic materials, in contrast to extensive chemical and isotopic analyses. It is important to determine these properties as they are related to disruption and fragmentation of bolides and asteroids, and activities related to sample return and hazardous asteroid mitigation. Here we present results from an ongoing suite of scale-dependent studies of meteorite strength and fragmentation. The meteorites studied are Tamdakht (H5), an ordinary chondrite that exhibits a heterogeneous structure criss-crossed with shock veins and centimeter-sized regions of white and light grey, and the carbonaceous chondrite Allende (CV3), which suitable pieces are light grey with abundant chondrules and CAIs. Uniaxial compression tests are performed on meteorite cubes ranging from 0.5 to 4 centimeters using an Instron 5985 frame with a 250 kN load cell and compression fixtures with 145mm diameter radial platens. All tests are conducted at room temperature and in displacement control with a displacement rate of 0.25 mm per minute to ensure quasi-static conditions. A three-dimensional digital image correlation (DIC) system that enables noncontact measurement of displacement and strain fields is also used. Analysis of the strength and failure process of the two meteorite types is conducted and compared to terrestrial materials.

  13. Scale-Dependent Measurements of Meteorite Strength and Fragmentation: Tamdakht (H5) and Allende (CV3).

    NASA Astrophysics Data System (ADS)

    Cotto-Figueroa, D.; Asphaug, E. I.; Garvie, L. A. J.; Morris, M. A.; Rai, A.; Chattopadhyay, A.; Johnston, J.; Borkowski, L.

    2015-12-01

    Meteorites are pieces of natural space debris, which have survived ejection from their parent bodies and passage through the Earth's atmosphere. As such, they provide a unique opportunity to study the fundamental physical and mechanical properties of early Solar System materials. But to date, few direct studies of physical properties have been conducted on meteoritic materials, in contrast to extensive chemical and isotopic analyses. It is important to determine these properties as they are related to disruption and fragmentation of bolides and asteroids, and activities related to sample return and hazardous asteroid mitigation. Here we present results from an ongoing suite of scale-dependent studies of meteorite strength and fragmentation. The meteorites studied are Tamdakht (H5), an ordinary chondrite that exhibits a heterogeneous structure criss-crossed with shock veins and centimeter-sized regions of white and light grey, and the carbonaceous chondrite Allende (CV3), which suitable pieces are light grey with abundant chondrules and CAIs. Uniaxial compression tests are performed on meteorite cubes ranging from 0.5 to 4 centimeters using an Instron 5985 frame with a 250 kN load cell and compression fixtures with 145mm diameter radial platens. All tests are conducted at room temperature and in displacement control with a displacement rate of 0.25 mm per minute to ensure quasi-static conditions. A three-dimensional digital image correlation (DIC) system that enables noncontact measurement of displacement and strain fields is also used. Analysis of the strength and failure process of the two meteorite types is conducted and compared to terrestrial materials.

  14. Alteration on asteroids: Insights from CM/CI meteorite mineralogy and midwave-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    McAdam, M.; Sunshine, J.; Kelley, M.; Howard, K.; McCoy, T.

    2014-07-01

    Introduction: Primitive, dark asteroids have few spectral features in the visible and near-infrared (NIR) in the 0.5--2.5 μ m region. Traditional classification of these asteroids has relied mainly on the presence of a 0.7 μ m charge-transfer band and the slope of the spectrum in the NIR. While the 0.7 μ m charge-transfer band has been attributed to phyllosilicates, the presence of this band is uncorrelated to total amount of phyllosilicates in well studied CM/CI meteorites. It is, therefore, not possible to identify specific compositions or water content of asteroids using this wavelength region. The work presented here seeks to augment the understanding of the composition of dark asteroids by studying CM/CI meteorites in the mid-infrared (MIR, 8 to 25 μ m). Observed compositional trends as a function of alteration in the MIR spectra of well-studied CM/CI meteorites are used as a basis for interpreting MIR spectra of asteroids. MIR Studies of CM/CI meteorites: CM and CI meteorites have well understood mineralogical variations. These meteorites underwent a water-rock reaction (aqueous alteration) on their parent bodies. This reaction converted their initially anhydrous silicates into hydrated phyllosilicates. In many meteorites, this process is incomplete. As such, the meteorites are complex mixtures of phyllosilicates, anhydrous silicates, and accessory phases. The MIR spectra of the CM/CI meteorites reflect this complexity. Our studies indicate that features in the 10--13 μ m region are combination features of Mg-rich phyllosilicate absorptions and anhydrous olivine. The position of this feature is directly correlated to total abundance of phyllosilicates and therefore can be used remotely to determine the amount of alteration an asteroid has experienced. Preliminary Studies of Dark Asteroids: Preliminary studies of dark asteroids using archived Spitzer Space Telescope Infrared Spectrograph data show that some dark asteroids have features that are similar to

  15. Formation of thin sulfide rinds on the CM parent body. [Abstract only

    NASA Technical Reports Server (NTRS)

    Browning, L. B.; Mcsween, H. Y., Jr.; Zolensky, M.

    1994-01-01

    Many of the textures that are observed in CM chondrites have been alternately assigned nebular, parent-body, or combined nebular-parent body origins. Since it is very difficult to substantiate the production of complex textures in the nebula, an alternate approach to this problem is to rigorously determine which of the observable textures could have been produced by reasonable aqueous alteration processes on the CM parent body. Potential parent body reactions involving S deserve special attention because S-bearing phase define many important CM textures, such as rims. We have examined the possibility that the thin (about 5 microns) rinds of sulfides observed around some partially dissolved olivines within the chondrules and matrixes of CM chondrites were formed by the preferential precipitation of sulfides at or near dissolving olivine boundaries during parent-body alteration. Our model defines two infinite and parallel planes of olivine that are separated by pure water. Average separation distances between olivine grains in CM chondrites at the time of accretion (about 100-200 microns) were estimated by assuming a closed system fluid/rock ratio of 45% and varying the bimodal grain-size distribution. We restrict our calculations to the case of an isochemical system with sufficient bisulfide in solution to account for precipitation of pyrrhotite at STP. Our model examines the possibility that dissolving olivines with compositions between Fo(sub 0.9) and Fo(sub 0.4) can produce a strong gradient of Fe(2+) at pHs from 7 to 12 such that the precipitation of pyrrhotite will be initiated at the olivine-fluid boundary. Since CM phase equilibria is consistent with highly reducing conditions, Fe released by olivines would largely remain in solution as Fe(2+) until the solubility product of a Fe(2+) bearing phase was exceeded. Our calculations indicate that all examined combinations of olivine composition and pH yield a strong Fe(2+) gradient at the time the pyrrhotite

  16. Early Thermal Evolution of Planetesimals and Its Impact on Processing and Dating of Meteoritic Material

    NASA Astrophysics Data System (ADS)

    Gail, H.-P.; Trieloff, M.; Breuer, D.; Spohn, T.

    Radioisotopic ages for meteorites and their components provide constraints on the evolution of small bodies: timescales of accretion, thermal and aqueous metamorphism, differentiation, cooling, and impact metamorphism. Realizing that the decay heat of short-lived nuclides (e.g., 26Al, 60Fe) was the main heat source driving differentiation and metamorphism, thermal modeling of small bodies is of the utmost importance to set individual meteorite age data into the general context of the thermal evolution of their parent bodies, and to derive general conclusions about the nature of planetary building blocks in the early solar system. As a general result, modeling easily explains that iron meteorites are older than chondrites, as early formed planetesimals experienced a higher concentration of short-lived nuclides and more severe heating. However, core formation processes may also extend to 10 million years (m.y.) after the formation of calcium-aluminum-rich inclusions (CAIs). A general effect of the porous nature of the starting material is that relatively small bodies (less than a few kilometers) will also differentiate if they form within 2 m.y. after CAIs. A particular interesting feature to be explored is the possibility that some chondrites may derive from the outer undifferentiated layers of asteroids that are differentiated in their interiors. This could explain the presence of remnant magnetization in some chondrites due to a planetary magnetic field.

  17. Outcome of impact disruption of iron meteorites at room temperature

    NASA Astrophysics Data System (ADS)

    Katsura, T.; Nakamura, A.; Takabe, A.; Okamoto, T.; Sangen, K.; Hasegawa, S.; Liu, X.; Mashimo, T.

    2014-07-01

    The iron meteorites and some M-class asteroids are generally understood to originate in the cores of differentiated planetesimals or in the local melt pools of primitive bodies. On these primitive bodies and planetesimals, a wide range of collisional events at different mass scales, temperatures, and impact velocities would have occurred. Iron materials have a brittle-ductile transition at a certain temperature, which depends on metallurgical factors such as grain size and purity, and on conditions such as strain-rate and confining pressure [1]. An evolutional scenario of iron meteorite parent bodies was proposed in which they formed in the terrestrial planet region, after which they were scattered into the main belt by collisions, Yarkovsky thermal forces, and resonances [2]. In this case, they may have experienced collisional evolution in the vicinity of the Earth before they were scattered into the main belt. The size distribution of iron bodies in the main belt may therefore have depended on the disruption threshold of iron bodies at temperature above the brittle-ductile transition. This paper presents the results of impact-disruption experiments of iron meteorite and steel specimens mm-cm in size as projectiles or targets conducted at room temperature using three light-gas guns and one powder gun. Our iron specimens were almost all smaller in size than their counterparts (as targets or projectiles, respectively). The fragment size distribution of iron material was different from that of rocks. In iron fragmentation, a higher percentage of the mass is concentrated in larger fragments, i.e., the mass fraction of fine fragments is much less than that of rocks shown in the Figure (left). This is probably due to the ductile nature of the iron materials at room temperature. Furthermore, the Figure (right) shows that the largest fragment mass fraction f is dependent not only on the energy density but also on the size of the specimens. In order to obtain a generalized

  18. The Old Woman, California, IIAB iron meteorite

    NASA Astrophysics Data System (ADS)

    Plotkin, Howard; Clarke, Roy S.; McCoy, Timothy J.; Corrigan, Catherine M.

    2012-05-01

    The Old Woman meteorite, discovered in March 1976 by two prospectors searching for a fabled lost Spanish gold mine in mountains ˜270 km east of Los Angeles, has achieved the status of a legend among meteorite hunters and collectors. The question of the ownership of the 2753 kg group IIAB meteorite, the second largest ever found in the United States (34°28'N, 115°14'W), gave rise to disputes involving the finders, the Bureau of Land Management, the Secretary of the Department of the Interior, the State of California, the California members of the U.S. Congress, various museums in California, the Smithsonian Institution, and the Department of Justice. Ultimately, ownership of the meteorite was transferred to the Smithsonian under the powers of the 1906 Antiquities Act, a ruling upheld in a U.S. District Court and a U.S. Court of Appeals. After additional debate, the Smithsonian removed a large cut for study and curation, and for disbursement of specimens to qualified researchers. The main mass was then returned to California on long-term loan to the Bureau of Land Management's Desert Discovery Center in Barstow. The Old Woman meteorite litigation served as an important test case for the ownership and control of meteorites found on federal lands. The Old Woman meteorite appears to be structurally unique in containing both hexahedral and coarsest octahedral structures in the same mass, unique oriented schreibersites within hexahedral areas, and polycrystalline parent austenite crystals. These structures suggest that different portions of the meteorite may have transformed via different mechanisms upon subsolidus cooling, making the large slices of Old Woman promising targets for future research.

  19. [Parenting].

    ERIC Educational Resources Information Center

    Pawl, Jeree, Ed.

    1990-01-01

    Contributions to this theme issue of a bulletin on infants aged birth to three, point out that becoming a parent is an evolving process and that infants' meanings to their parents shape parenting behavior and the capacity to change. Articles also examine the challenge of how to support parents as they come to, and continue in, the process of…

  20. Unlocking the zinc isotope systematics of iron meteorites

    NASA Astrophysics Data System (ADS)

    Bridgestock, L. J.; Williams, H.; Rehkämper, M.; Larner, F.; Giscard, M. D.; Hammond, S.; Coles, B.; Andreasen, R.; Wood, B. J.; Theis, K. J.; Smith, C. L.; Benedix, G. K.; Schönbächler, M.

    2014-08-01

    Zinc isotope compositions (δ66Zn) and concentrations were determined for metal samples of 15 iron meteorites across groups IAB, IIAB, and IIIAB. Also analyzed were troilite and other inclusions from the IAB iron Toluca. Furthermore, the first Zn isotope data are presented for metal-silicate partitioning experiments that were conducted at 1.5 GPa and 1650 K. Three partitioning experiments with run durations of between 10 and 60 min provide consistent Zn metal-silicate partition coefficients of ∼0.7 and indicate that Zn isotope fractionation between molten metal and silicate is either small (at less than about ±0.2‰) or absent. Metals from the different iron meteorite groups display distinct ranges in Zn contents, with concentrations of 0.08-0.24 μg/g for IIABs, 0.8-2.5 μg/g for IIIABs, and 12-40 μg/g for IABs. In contrast, all three groups show a similar range of δ66Zn values (reported relative to ‘JMC Lyon Zn’) from +0.5‰ to +3.0‰, with no clear systematic differences between groups. However, distinct linear trends are defined by samples from each group in plots of δ66Zn vs. 1/Zn, and these correlations are supported by literature data. Based on the high Zn concentration and δ66Zn ≈ 0 determined for a chromite-rich inclusion of Toluca, modeling is employed to demonstrate that the Zn trends are best explained by segregation of chromite from the metal phase. This process can account for the observed Zn-δ66Zn-Cr systematics of iron meteorite metals, if Zn is highly compatible in chromite and Zn partitioning is accompanied by isotope fractionation with Δ66Znchr-met≈-1.5‰. Based on these findings, it is likely that the parent bodies of the IAB complex, IIAB and IIIAB iron meteorites featured δ66Zn values of about -1.0 to +0.5‰, similar to the Zn isotope composition inferred for the bulk silicate Earth and results obtained for chondritic meteorites. Together, this implies that most solar system bodies formed with similar bulk Zn isotope

  1. I-Xe ages of Campo del Cielo silicates as a record of the complex early history of the IAB parent body

    NASA Astrophysics Data System (ADS)

    Pravdivtseva, O.; Meshik, A.; Hohenberg, C. M.; Kurat, G.

    2013-12-01

    Using in situ laser analyses of a polished thin section from the IAB iron meteorite Campo del Cielo, we identified two silicate grains rich in radiogenic 129*Xe, Cr-diopside, and oligoclase, excavated them from the metal, and irradiated them with thermal neutrons for I-Xe dating. The release profiles of 129*Xe and 128*Xe are consistent with these silicates being diopside and oligoclase, with activation energies, estimated using Arrhenius plots, of ˜201 and ˜171 kcal mole-1, respectively. The 4556.4 ± 0.4 Ma absolute I-Xe age of the more refractory diopside is younger than the 4558.0 ± 0.7 Ma I-Xe age of the less refractory oligoclase. We suggest that separate impact events at different locations and depths on a porous initial chondritic IAB parent body led to the removal of the melt and recrystallization of diopside and oligoclase at the times reflected by their respective I-Xe ages. The diopside and oligoclase grains were later brought into the studied inclusion by a larger scale catastrophic collision that caused breakup and reassembly of the debris, but did not reset the I-Xe ages dating the first events. The metal melt most probably was <1250 °C when it surrounded studied silicate grains. This reassembly could not have occurred earlier than the I-Xe closure in diopside at 4556.4 ± 0.4 Ma.

  2. A numerical treatment of melt/solid segregation - Size of the eucrite parent body and stability of the terrestrial low-velocity zone

    NASA Technical Reports Server (NTRS)

    Walker, D.; Stolper, E. M.; Hays, J. F.

    1978-01-01

    Crystal sinking to form cumulates and melt percolation toward segregation in magma pools can be treated with modifications of Stokes' and Darcy's laws, respectively. The velocity of crystals and melt depends, among other things, on the force of gravity (g) driving the separations and the cooling time of the environment. The increase of g promotes more efficient differentiation, whereas the increase of cooling rate limits the extent to which crystals and liquid can separate. The rate at which separation occurs is strongly dependent on the proportion of liquid that is present. The observation of cumulates and segregated melts among the eucrite meteorites is used as a basis for calculating the g (and planet size) required to perform these differentiations. The eucrite parent body was probably at least 10-100 km in radius. The earth's low velocity zone (LVZ) is shown to be unstable with respect to draining itself of excess melt if the melt forms an interconnecting network. A geologically persistent LVZ with a homogeneous distribution of melt can be maintained with melt fractions only on the order of 0.1% or less.

  3. S-asteroids 387 Aquitania and 980 Anacostia - Possible fragments of the breakup of a spinel-bearing parent body with CO3/CV3 affinities

    NASA Technical Reports Server (NTRS)

    Burbine, Thomas H.; Gaffey, Michael J.; Bell, Jeffrey F.

    1992-01-01

    Asteroids 387 Aquitania and 980 Anacostia are anomalous members of the S-class. Their reflectance spectra exhibit a strong broad absorption feature longwards of 1.5 micron and no significant feature near 1 micron. Their spectra indicate the presence of spinel, an aluminum-magnesium oxide mineral commonly present in inclusions in CV3 and CO3 meteorites. Spinel probably makes up only a small percentage of the surface assemblages of these asteroids, but its spectral effect may be enhanced by its presence in fine-grained white inclusions in immature asteroid regoliths. It is speculated that Aquitania and Anacostia represent material formed in the same nebular zone as the CV3 and CO3 chondrites but either: (A) at an earlier time in the nebula when such inclusions might have been a relatively larger fraction of the nebular grain population; or (B) in local regions where nebular processes (e.g., settling to the midplane) had concentrated such inclusions. The close similarity of two orbital elements (a, i) suggests that Aquitania and Anacostia may be members of a partially dispersed asteroid family produced by the early disruption of a spinel-bearing parent body.

  4. 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.

  5. Mineralogical Variation of Chelyabinsk with Depth from the Surface of the Parent Meteoroid

    NASA Technical Reports Server (NTRS)

    Yoshida, S.; Mikouchi, T.; Nagao, K.; Haba, M. K.; Hasegawa, H.; Komatsu, M.; Zolensky, M. E.

    2014-01-01

    The Chelyabinsk meteorite, which passed over the Chelyabinsk Oblast, Russia on Feb. 15th, 2013, brought serious damage by the shock wave and airburst. The diameter of the parent meteoroid is estimated to be approximately 20 m in diameter [1]. It was reported that the impact by this meteorite shower was 4,000 times as large as the TNT explosive and this was the largest airburst on Earth since the asteroid impact in Tunguska, Russia in 1908. The mineralogy and geochemical study of the recovered samples shows that Chelyabinsk is an LL5 chondrite [1]. In this study we analyzed several fragments of Chelyabinsk whose noble gas compositions have been measured and depths from the surface of the parent meteoroid were estimated [2]. We examined how mineralogical characteristics change with depth from the surface. This kind of study has never been performed and thus may be able to offer significant information about the evolution of meteorite parent bodies.

  6. Antarctic Meteorite Newsletter

    NASA Technical Reports Server (NTRS)

    Lindstrom, Marilyn

    2000-01-01

    This newsletter contains something for everyone! It lists classifications of about 440 meteorites mostly from the 1997 and 1998 ANSMET (Antarctic Search for Meteorites) seasons. It also gives descriptions of about 45 meteorites of special petrologic type. These include 1 iron, 17 chondrites (7 CC, 1 EC, 9 OC) and 27 achondrites (25 HED, UR). Most notable are an acapoloite (GRA98028) and an olivine diogenite (GRA98108).

  7. Fluorine in meteorites

    NASA Technical Reports Server (NTRS)

    Allen, R. O., Jr.; Clark, P. J.

    1977-01-01

    Microanalysis using a resonant nuclear reaction was used to measure F concentrations in USGS standard rocks and 21 meteorites. The F appears to be a moderately depleted element, but there were significant variations within each sample. Measurements on separated metal phases suggest that about 20% of meteoritic F is in the metal or in a phase closely associated with it. Simultaneous measurements of F, Mg, Na, Al and Si in the nonmagnetic fractions of meteorites suggest plagioclase as a F containing phase.

  8. Microtextural Study of Feldspar in Petrologic Type 3 LL Ordinary Chondrites: A Record of Parent Body Metasomatism

    NASA Astrophysics Data System (ADS)

    Lewis, J. A.; Jones, R. H.

    2014-09-01

    We have carried out a detailed study of LL3 ordinary chondrites, focusing on the chemical and microtextural development of feldspar, to help understand the low-temperature evolution of the LL parent body(ies).

  9. Chirality of meteoritic free and IOM-derived monocarboxylic acids and implications for prebiotic organic synthesis

    NASA Astrophysics Data System (ADS)

    Aponte, José C.; Tarozo, Rafael; Alexandre, Marcelo R.; Alexander, Conel M. O.'D.; Charnley, Steven B.; Hallmann, Christian; Summons, Roger E.; Huang, Yongsong

    2014-04-01

    The origin of homochirality and its role in the development of life on Earth are among the most intriguing questions in science. It has been suggested that carbonaceous chondrites seeded primitive Earth with the initial organic compounds necessary for the origin of life. One of the strongest pieces of evidence supporting this theory is that certain amino acids in carbonaceous chondrites display a significant L-enantiomeric excess (ee), similar to those use by terrestrial life. Analyses of ee in meteoritic molecules other than amino acids would shed more light on the origins of homochirality. In this study we investigated the stereochemistry of two groups of compounds: (1) free monocarboxylic acids (MCAs) from CM2 meteorites LON 94101 and Murchison; and (2) the aliphatic side chains present in the insoluble organic matter (IOM) and extracted in the form of monocarboxylic acids (MCAs) from EET 87770 (CR2) and Orgueil (CI1). Contrary to the well-known ee observed for amino acids in meteorites, we found that meteoritic branched free and IOM-derived MCAs with 5-8 carbon atoms are essentially racemic. The racemic nature of these compounds is used to discuss the possible influence of ultraviolet circularly polarized light (UVCPL) and aqueous alterations on the parent body on chirality observed in in carbonaceous chondrites.

  10. Comparisons of Mineralogy Between Cumulate Eucrites and Lunar Meteorites Possibly from the Farside Anorsothitic Crust

    NASA Technical Reports Server (NTRS)

    Takeda, H.; Yamaguchi, A.; Hiroi, T.; Nyquist, L. E.; Shih, C.-Y.; Ohtake, M.; Karouji, Y.; Kobayashi, S.

    2011-01-01

    Anorthosites composed of nearly pure anorthite (PAN) at many locations in the farside highlands have been observed by the Kaguya multiband imager and spectral profiler [1]. Mineralogical studies of lunar meteorites of the Dhofar 489 group [2,3] and Yamato (Y-) 86032 [4], all possibly from the farside highlands, showed some aspects of the farside crust. Nyquist et al. [5] performed Sm-Nd and Ar-Ar studies of pristine ferroan anorthosites (FANs) of the returned Apollo samples and of Dhofar 908 and 489, and discussed implications for lunar crustal history. Nyquist et al. [6] reported initial results of a combined mineralogical/chronological study of the Yamato (Y-) 980318 cumulate eucrite with a conventional Sm-Nd age of 4567 24 Ma and suggested that all eucrites, including cumulate eucrites, crystallized from parental magmas within a short interval following differentiation of their parent body, and most eucrites participated in an event or events in the time interval 4400- 4560 Ma in which many isotopic systems were partially reset. During the foregoing studies, we recognized that variations in mineralogy and chronology of lunar anorthosites are more complex than those of the crustal materials of the HED parent body. In this study, we compared the mineralogies and reflectance spectra of the cumulate eucrites, Y-980433 and 980318, to those of the Dhofar 307 lunar meteorite of the Dhofar 489 group [2]. Here we consider information from these samples to gain a better understanding of the feldspathic farside highlands and the Vesta-like body.

  11. Impact history of the Chelyabinsk meteorite: Electron microprobe and LA-ICP-MS study of sulfides and metals

    NASA Astrophysics Data System (ADS)

    Andronikov, A. V.; Andronikova, I. E.; Hill, D. H.

    2015-12-01

    Electron microprobe and LA-ICP-MS study of sulfides and metals from two fragments of the LL5 Chelyabinsk meteorite were conducted. The fragments are impact breccias, one fragment contains both chondritic and shock vein lithologies, and the other contains shock-darkened chondritic clasts and vesicular impact melts. The chondritic lithology and shock veins display very similar opaque mineral compositions. The mineral compositions in the impact-melt breccias are distinctly different. The brecciated state of the Chelyabinsk meteorite suggests strong involvement of shock-related processes during the evolution of the parent body. Multiple heavy impact events occurred on the parent asteroid and on the Chelyabinsk meteoroid itself over the time period from ca. 4.5 Ga until ca. 1.2 Ma. The shock veins were produced in situ on the parent body. The impact-melt breccias could have formed because of the dramatic impact to the parent LL-chondrite body that could be partly disintegrated. The fragment containing shock-darkened chondritic clasts and vesicular impact melt lithologies preserves a record of melting, volatilization, partial degassing, and quenching of the molten material. The abundance and size (up to 1 mm) of the vesicles suggest that the impact melt must have been buried at some depth after formation. After impact and subsequent melting occurred, the impact-induced pressure on the shallow asteroid interior was released that caused "boiling" of volatiles and generation of S-rich bubbles. Such an impact excavated down to depths of the body generating multiple fragments with complicated histories. These fragments reaccumulated into a gravitational aggregate and formed the parental meteoroid for the Chelyabinsk meteorite.

  12. Possible Thermal Metamorphism on the C Asteroids Seen from the 3-micrometer Hydration Band in Comparison with Heated CI/CM Meteorites

    NASA Astrophysics Data System (ADS)

    Hiroi, T.; Pieters, C. M.; Zolensky, M. E.; Lipschutz, M. E.

    1995-09-01

    Thermal metamorphism study of the C (including G, B, and F) asteroids [1] is revisited using their selected reflectance spectra (0.3-3.6 micrometers) [2]. Laboratory spectra of some carbonaceous chondrites and heated Murchison samples [3] have been also measured for comparison. Both CI1 and CM2 meteorites have a characteristic 3-micrometer hydration band [4] at various strengths, and most CM2 meteorites also have 0.7, 0.9, and 1.1-micrometer bands due to ferric/ferrous Fe in septechlorites (Fig. 1). The unusual CI/CM meteorites (Y-86720, B-7904, Y-82162, etc.) that have evidence of thermal metamorphism have no 0.7-micrometer band but still have a weak 3-micrometer band. The 3-micrometer band of heated Murchison samples is gradually reduced for samples heated up to 500 degrees C and gone around 600 degrees C. The 0.7-micrometer band is gone even before 400 degrees C. The 3-micrometer band strengths of the unusual CI/CM meteorites correspond to the heating temperature between 500 and 600 degrees C if the process was similar to the Murchison heating experiment. None of the C asteroids have both the 3-micrometer band strength and overall spectral profile comparable to the common CI/CM meteorites studied here. Among the seven selected asteroids, only two have a meteorite counterpart over this wavelength range. Asteroid 511 Davida and B-7904 are the best counterparts in both spectral shape and brightness (Fig. 1). Existence of the unusual CI/CM meteorites suggests that there were their parent bodies that contained water (ice) at appropriate temperatures over sufficient time to induce aqueous alteration and were subsequently heated up to 500-600 degrees C. It has been recently suggested that some dark inclusions of Vigarano (CV3) experienced extensive aqueous alteration followed by complete dehydration and recrystallization [5]. Since dark inclusions are common in all CV3 meteorites, aqueous alteration and late-stage heating may have been widespread on the CV3 parent

  13. Parental Midlife Body Shape and Association with Multiple Adult Offspring Obesity Measures: North West Adelaide Health Study

    PubMed Central

    2015-01-01

    There is compelling evidence that parental weight is a strong determinant of offspring weight status. The study used cross-sectional self-reported and measured data from a longitudinal cohort of Australian adults (n = 2128) from Stage 3 (2008–10) of the North West Adelaide Health Study (1999–2003, baseline n = 4056) to investigate the association between midlife parental body shape and four indicators of obesity and fat distribution. The analysis used measured body mass index (BMI), waist circumference (WC), waist hip ratio (WHR) and waist height ratio (WHtR) of adult offspring, together with pictograms for recall of parental body shape. Compared to both parents being a healthy weight, offspring were more likely to be overweight or obese if both parents were an unhealthy weight at age 40 (OR 2.14, 95% CI 1.67–2.76) and further, those participants whose mother was an unhealthy weight were more likely to be overweight or obese themselves (OR 1.50, 95% CI 1.14–1.98). There were similar but lower results for those with an overweight/obese father (OR 1.44, 95% CI 1.08–1.93). The effect of one or both parents being overweight or obese tended to be stronger for daughters than for sons across BMI, WC and WHtR. BMI showed the strongest association with parental body shape (OR 2.14), followed by WC (OR 1.78), WHtR (OR 1.71) and WHR (OR 1.45). WHtR (42–45%) and BMI (35–36%) provided the highest positive predictive values for overweight/obesity from parental body shape. Parental obesity increases the risk of obesity for adult offspring, both for overall body shape and central adiposity, particularly for daughters. Pictograms could potentially be used as a screening tool in primary care settings to promote healthy weight among young adults. PMID:26355742

  14. Dynamical evidence regarding the relationship between asteroids and meteorites

    NASA Technical Reports Server (NTRS)

    Wetherill, G. W.

    1978-01-01

    Meteorites are fragments of small solar system bodies transferring into the vicinity of earth from the inner edge of the asteroid belt. Photometric measurements support an association between Apollo objects and chondritic meteorites. Dynamical arguments indicate that most Apollo objects are devolatilized comet residues, however; petrographic and cosmogonical reasons argue against this conclusion.

  15. Radar-enabled recovery of the Sutter's Mill meteorite, a carbonaceous chondrite regolith breccia.

    PubMed

    Jenniskens, Peter; Fries, Marc D; Yin, Qing-Zhu; Zolensky, Michael; Krot, Alexander N; Sandford, Scott A; Sears, Derek; Beauford, Robert; Ebel, Denton S; Friedrich, Jon M; Nagashima, Kazuhide; Wimpenny, Josh; Yamakawa, Akane; Nishiizumi, Kunihiko; Hamajima, Yasunori; Caffee, Marc W; Welten, Kees C; Laubenstein, Matthias; Davis, Andrew M; Simon, Steven B; Heck, Philipp R; Young, Edward D; Kohl, Issaku E; Thiemens, Mark H; Nunn, Morgan H; Mikouchi, Takashi; Hagiya, Kenji; Ohsumi, Kazumasa; Cahill, Thomas A; Lawton, Jonathan A; Barnes, David; Steele, Andrew; Rochette, Pierre; Verosub, Kenneth L; Gattacceca, Jérôme; Cooper, George; Glavin, Daniel P; Burton, Aaron S; Dworkin, Jason P; Elsila, Jamie E; Pizzarello, Sandra; Ogliore, Ryan; Schmitt-Kopplin, Phillipe; Harir, Mourad; Hertkorn, Norbert; Verchovsky, Alexander; Grady, Monica; Nagao, Keisuke; Okazaki, Ryuji; Takechi, Hiroyuki; Hiroi, Takahiro; Smith, Ken; Silber, Elizabeth A; Brown, Peter G; Albers, Jim; Klotz, Doug; Hankey, Mike; Matson, Robert; Fries, Jeffrey A; Walker, Richard J; Puchtel, Igor; Lee, Cin-Ty A; Erdman, Monica E; Eppich, Gary R; Roeske, Sarah; Gabelica, Zelimir; Lerche, Michael; Nuevo, Michel; Girten, Beverly; Worden, Simon P

    2012-12-21

    Doppler weather radar imaging enabled the rapid recovery of the Sutter's Mill meteorite after a rare 4-kiloton of TNT-equivalent asteroid impact over the foothills of the Sierra Nevada in northern California. The recovered meteorites survived a record high-speed entry of 28.6 kilometers per second from an orbit close to that of Jupiter-family comets (Tisserand's parameter = 2.8 ± 0.3). Sutter's Mill is a regolith breccia composed of CM (Mighei)-type carbonaceous chondrite and highly reduced xenolithic materials. It exhibits considerable diversity of mineralogy, petrography, and isotope and organic chemistry, resulting from a complex formation history of the parent body surface. That diversity is quickly masked by alteration once in the terrestrial environment but will need to be considered when samples returned by missions to C-class asteroids are interpreted.

  16. Radar-Enabled Recovery of the Sutters Mill Meteorite, a Carbonaceous Chondrite Regolith Breccia

    NASA Technical Reports Server (NTRS)

    Jenniskens, Petrus M.; Fries, Marc D.; Yin, Qing-Zhu; Zolensky, Michael E.; Krot, Alexander N.; Sandford, Scott A.; Sears, Derek; Beauford, Robert; Ebel, Denton S.; Friedrich, Jon M.; Nagashima, Kazuhide; Wimpenny, Josh; Yamakawa, Akane; Nishiizumi, Kunihiko; Hamajima, Yasunori; Caffee, Marc W.; Welten, Kees C.; Laubenstein, Matthias; Davis, Andrew M.; Simon, Steven B.; Heck, Phillipp R.; Young, Edward D.; Kohl, Issaku E.; Thiemens, Mark H.; Nunn, Morgan H.; Mikouchi, Takashi; Hagiya, Kenji; Ohsumi, Kazumasa; Cahill, Thomas A.; Lawton, Jonathan A.; Barnes, David; Steele, Andrew; Rochette, Pierre; Verosub, Kenneth L.; Gattacceca, Jerome

    2012-01-01

    Doppler weather radar imaging enabled the rapid recovery of the Sutter's Mill meteorite after a rare 4-kiloton of TNT-equivalent asteroid impact over the foothills of the Sierra Nevada in northern California. The recovered meteorites survived a record high-speed entry of 28.6 kilometers per second from an orbit close to that of Jupiter-family comets (Tisserand's parameter = 2.8 +/- 0.3). Sutter's Mill is a regolith breccia composed of CM (Mighei)-type carbonaceous chondrite and highly reduced xenolithic materials. It exhibits considerable diversity of mineralogy, petrography, and isotope and organic chemistry, resulting from a complex formation history of the parent body surface. That diversity is quickly masked by alteration once in the terrestrial environment but will need to be considered when samples returned by missions to C-class asteroids are interpreted.

  17. Radar-enabled recovery of the Sutter's Mill meteorite, a carbonaceous chondrite regolith breccia.

    PubMed

    Jenniskens, Peter; Fries, Marc D; Yin, Qing-Zhu; Zolensky, Michael; Krot, Alexander N; Sandford, Scott A; Sears, Derek; Beauford, Robert; Ebel, Denton S; Friedrich, Jon M; Nagashima, Kazuhide; Wimpenny, Josh; Yamakawa, Akane; Nishiizumi, Kunihiko; Hamajima, Yasunori; Caffee, Marc W; Welten, Kees C; Laubenstein, Matthias; Davis, Andrew M; Simon, Steven B; Heck, Philipp R; Young, Edward D; Kohl, Issaku E; Thiemens, Mark H; Nunn, Morgan H; Mikouchi, Takashi; Hagiya, Kenji; Ohsumi, Kazumasa; Cahill, Thomas A; Lawton, Jonathan A; Barnes, David; Steele, Andrew; Rochette, Pierre; Verosub, Kenneth L; Gattacceca, Jérôme; Cooper, George; Glavin, Daniel P; Burton, Aaron S; Dworkin, Jason P; Elsila, Jamie E; Pizzarello, Sandra; Ogliore, Ryan; Schmitt-Kopplin, Phillipe; Harir, Mourad; Hertkorn, Norbert; Verchovsky, Alexander; Grady, Monica; Nagao, Keisuke; Okazaki, Ryuji; Takechi, Hiroyuki; Hiroi, Takahiro; Smith, Ken; Silber, Elizabeth A; Brown, Peter G; Albers, Jim; Klotz, Doug; Hankey, Mike; Matson, Robert; Fries, Jeffrey A; Walker, Richard J; Puchtel, Igor; Lee, Cin-Ty A; Erdman, Monica E; Eppich, Gary R; Roeske, Sarah; Gabelica, Zelimir; Lerche, Michael; Nuevo, Michel; Girten, Beverly; Worden, Simon P

    2012-12-21

    Doppler weather radar imaging enabled the rapid recovery of the Sutter's Mill meteorite after a rare 4-kiloton of TNT-equivalent asteroid impact over the foothills of the Sierra Nevada in northern California. The recovered meteorites survived a record high-speed entry of 28.6 kilometers per second from an orbit close to that of Jupiter-family comets (Tisserand's parameter = 2.8 ± 0.3). Sutter's Mill is a regolith breccia composed of CM (Mighei)-type carbonaceous chondrite and highly reduced xenolithic materials. It exhibits considerable diversity of mineralogy, petrography, and isotope and organic chemistry, resulting from a complex formation history of the parent body surface. That diversity is quickly masked by alteration once in the terrestrial environment but will need to be considered when samples returned by missions to C-class asteroids are interpreted. PMID:23258889

  18. Identifying meteorite source regions through near-Earth object spectroscopy

    NASA Astrophysics Data System (ADS)

    Thomas, Cristina A.; Binzel, Richard P.

    2010-02-01

    By virtue of their landing on Earth, meteorites reside in near-Earth object (NEO) orbits prior to their arrival. Thus the population of observable NEOs, in principle, gives important representation of meteorite source bodies. By linking meteorites to NEOs, and linking NEOs to their most likely main-belt source locations, we seek to gain insight into the original Solar System formation locations for different meteorite classes. To forge possible links between meteorites and NEOs, we have developed a three dimensional method for quantitative comparisons between laboratory measurements of meteorites and telescopic measurements of near-Earth objects. We utilize meteorite spectra from the Reflectance Experiment Laboratory (RELAB) database and NEO data from the SpeX instrument on the NASA Infrared Telescope Facility (IRTF). Using the Modified Gaussian Model (MGM) as a mathematical tool, we treat asteroid and meteorite spectra identically in the calculation of 1-μm and 2-μm Geometric Band Centers and their Band Area Ratios (BARs). Using these identical numerical parameters we quantitatively compare the spectral properties of S-, Sq-, Q- and V-type NEOs with the spectral properties of the meteorites in four classes: H, L, LL and HED. For each NEO spectrum, we assign a set of probabilities for it being related to each of these four meteorite classes. Our NEO-meteorite correlation probabilities are then convolved with NEO-source region probabilities to yield a final set of meteorite-source region correlations. While the ν6 resonance dominates the delivery for all four meteorite classes, an excess (significant at the 2.1-sigma level) source region signature is found for the H chondrites through the 3:1 mean motion resonance. This results suggest an H chondrite source with a higher than average delivery preference through the 3:1 resonance. A 3:1 resonance H chondrite source region is consistent with the short cosmic ray exposure ages known for H chondrites.

  19. Don Quixote-A possible parent body of a meteor shower

    NASA Astrophysics Data System (ADS)

    Rudawska, Regina; Vaubaillon, Jeremie

    2015-12-01

    Asteroid 3552 Don Quixote (1983 SA) orbits the Sun on an orbit that resembles that of a short-period comet. This, together with its recently observed cometary activity, makes it a good candidate for a parent body of a meteor shower. Model calculations show that the particles originated from Don Quixote pass close enough to Earth orbit to search for a meteor shower activity. Corresponding meteor showers were found in CAMS (Rudawska and Jenniskens, 2014) and EDMOND (Kornoš et al., 2014) video observations. The κ Lyrids and August μ Draconids (IAU#464 and IAU#470, respectively), a similarly inclined stream active in the summer, are associated with 3552 Don Quixote.

  20. Molybdenum in eucrites - Evidence for a metal core in the eucrite parent body

    NASA Astrophysics Data System (ADS)

    Newsom, H. E.

    1985-02-01

    A modified metal-silicate extraction technique with neutron activation analysis has been used to determine Mo in a suite of eucrites. The concentrations of Mo in eucrites are found to be very low (15 to 70 ppb), similar to lunar samples. The eucrites have a mean Mo/La ratio of 0.0066, which is a factor of 570 lower then the CI chondrite ratio (3.75). The depletion of Mo and other siderophile elements in eucrites and their metal-to-silicate partition coefficients provide constraints on the metal content and the degree of partial melting during metal-silicate segregation in the eucrite parent body.

  1. Foundations of Forensic Meteoritics

    NASA Astrophysics Data System (ADS)

    Treiman, A. H.

    1992-07-01

    It may be useful to know if a meteorite was found at the site where it fell. For instance, the polymict ureilites North Haig and Nilpena were found 1100 km apart, yet are petrologically identical [1]. Could this distance represent transport from a single strewn field, or does it represent distinct fall sites? A meteorite may contain sufficient clues to suggest some characteristics of its fall site. If these inferences are inconsistent with the find site, one may infer that the meteorite has been transported. It will likely be impossible to determine the exact fall site of a transported meteorite. Data relevant to a meteorite's fall site may be intrinsic to the meteorite, or acquired at the site. For instance, an intrinsic property is terrestrial residence age (from abundances of cosmogenic radioisotopes and their decay products); a meteorite's terrestrial residence age must be the same or less than that of the surface on which it fell. After falling, a meteorite may acquire characteristic telltales of terrestrial geological, geochemical, and biological processes. These telltale clues may include products of chemical weathering, adhering geological materials, biological organisms living (or once living) on the meteorite, and biological materials adhering to (but never living on) the meteorite. The effects of chemical weathering, present in all but the freshest finds, range from slight rusting to extensive decomposition and veining The ages of weathering materials and veins, as with terrestrial residence ages above, must be less than the age of the fall surface. The mineralogy and chemistry, elemental and isotopic, of weathering materials will differ according to the mineralogy and composition of the meteorite, and the mineralogy, geochemistry, hydrology, and climate of the fall site. Weathering materials may also vary as climate changes and may vary among the microenvironments associated with a meteorite on the Earth's surface. Geological materials (rock, sediment

  2. Magnetism in meteorites

    NASA Technical Reports Server (NTRS)

    Herndon, J. M.; Rowe, M. W.

    1974-01-01

    An overview is presented of magnetism in meteorites. A glossary of magnetism terminology followed by discussion of the various techniques used for magnetism studies in meteorites are included. The generalized results from use of these techniques by workers in the field are described. A brief critical analysis is offered.

  3. Fullerenes in Allende Meteorite

    NASA Technical Reports Server (NTRS)

    Becker, L.; Bada, J. L.; Winans, R. E.; Bunch, T. E.

    1994-01-01

    The detection of fullerenes in deposits from meteor impacts has led to renewed interest in the possibility that fullerenes are present in meteorites. Although fullerenes have not previously been detected in the Murchison and Allende meteorites, the Allende meteorite is known to contain several well-ordered graphite particles which are remarkably similar in size and appearance to the fullerene-related structures carbon onions and nanotubes. We report that fullerenes are in fact present in trace amounts in the Allende meteorite. In addition to fullerenes, we detected many polycyclic aromatic hydrocarbons (PAHs) in the Allende meteorite, consistent with previous reports. In particular, we detected benzofluoranthene and corannulene (C20H10), five-membered ring structures which have been proposed as precursors to the formation of fullerene synthesis, perhaps within circumstellar envelopes or other sites in the interstellar medium.

  4. Combining Observations of Shock-induced Minerals with Calculations to Constrain the Shock History of Meteorites.

    NASA Astrophysics Data System (ADS)

    de Carli, P. S.; Xie, Z.; Sharp, T. G.

    2007-12-01

    All available evidence from shock Hugoniot and release adiabat measurements and from shock recovery experiments supports the hypothesis that the conditions for shock-induced phase transitions are similar to the conditions under which quasistatic phase transitions are observed. Transitions that require high temperatures under quasistatic pressures require high temperatures under shock pressures. The high-pressure phases found in shocked meteorites are almost invariably associated with shock melt veins. A shock melt vein is analogous to a pseudotachylite, a sheet of locally melted material that was quenched by conduction to surrounding cooler material. The mechanism by which shock melt veins form is not known; possible mechanisms include shock collisions, shock interactions with cracks and pores, and adiabatic shear. If one assumes that the phases within the vein crystallized in their stability fields, then available static high-pressure data constrain the shock pressure range over which the vein solidified. Since the veins have a sheet-like geometry, one may use one-dimensional heat flow calculations to constrain the cooling and crystallization history of the veins (Langenhorst and Poirier, 2000). Although the formation mechanism of a melt vein may involve transient pressure excursions, pressure equilibration of a mm-wide vein will be complete within about a microsecond, whereas thermal equilibration will require seconds. Some of our melt vein studies have indicated that the highly-shocked L chondrite meteorites were exposed to a narrow range of shock pressures, e.g., 18-25 GPa, over a minimum duration of the order of a second. We have used the Autodyn(TM) wave propagation code to calculate details of plausible impacts on the L-chondrite parent body for a variety of possible parent body stratigraphies. We infer that some meteorites probably represent material that was shocked at a depth of >10 km in their parent bodies.

  5. Early cosmic ray irradiation of chondrules and prolonged accretion of primitive meteorites

    NASA Astrophysics Data System (ADS)

    Beyersdorf-Kuis, Uta; Ott, Ulrich; Trieloff, Mario

    2015-08-01

    Chondrules, together with Ca-Al-rich inclusions (CAIs) and matrix, are the major constituents of primitive meteorites. It is clear that chondrules formed as molten objects and the conditions under which this happened seem well constrained. Partially overlapping in age, but mostly ∼2-3 million years younger than the CAIs, they appear to have formed over an extended period of time (e.g., Kita et al., 2013). We have analyzed chondrules in two highly primitive CR3 meteorites, QUE 99177 and MET 00426, and find that they contain highly variable amounts of noble gases produced by irradiation with cosmic rays. The lack of implanted solar wind and the composition of the cosmogenic component in QUE 99177 chondrules argue against irradiation in a parent body regolith, which leaves irradiation in the early solar system as the most likely explanation. The cosmogenic composition also points to irradiation primarily by galactic cosmic rays (GCR), not solar cosmic rays (SCR), i.e. not by an active early sun. To allow effective production of cosmogenic isotopes by GCR, but not SCR, this should have happened rather "late" in a largely, but not completely, dust-free environment. Our results support the suggestion that chondrules formed as free-floating objects in the solar nebula; also consistent with the noble gas data is pre-irradiation in small (∼dm-size) aggregates that broke up before or during accretion to the CR parent body. In both cases, chondrules spent an extended period of time before incorporation into the most primitive meteorite parent bodies, which puts constraints on accretion time scales.

  6. Meteoritic material on the moon

    NASA Technical Reports Server (NTRS)

    Morgan, J. W.; Ganapathy, R.; Higuchi, H.; Anders, E.

    1977-01-01

    Three types of meteoritic material are found on the moon: micrometeorites, ancient planetesimal debris from the "early intense bombardment," and debris of recent, craterforming projectiles. Their amounts and compositions have been determined from trace element studies. The micrometeorite component is uniformly distributed over the entire lunar surface, but is seen most clearly in mare soils. It has a primitive, C1-chondrite-like composition, and comprises 1 to 1.5 percent of mature soils. Apparently it represents cometary debris. The ancient component is seen in highland breccias and soils. Six varieties have been recognized, differing in their proportions of refractories (Ir, Re), volatiles (Ge, Sb), and Au. All have a fractionated composition, with volatiles depleted relative to siderophiles. The abundance patterns do not match those of the known meteorite classes. These ancient meteoritic components seem to represent the debris of an extinct population of bodies (planetisimals, moonlets) that produced the mare basins during the first 700 Myr of the moon's history. On the basis of their stratigraphy and geographic distribution, five of the six groups are tentatively assigned to specific mare basins: Imbrium, Serenitatis, Crisium, Nectaris, and Humorum or Nubium.

  7. Volatile degassing of basaltic achondrite parent bodies Evidence from alkali elements and phosphorus

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, David W.

    1987-01-01

    The Na, K, Rb, Cs, and P abundances in eucrites, diogenites, basaltic clasts from polymict eucrite, howardites, and mesosiderites are examined, and compared with an average of highly incompatible refractory (AHIR) elements normalized to cosmic abundances. It is observed that basaltic eucrites and basaltic clasts show a positive correlation between K, Rb, and Cs, and alkali element/AHIR ratios; the volatile loss of the alkali elements from the basalt affects the parent body inventory of volatile elements. The data reveal that for diogenites, the alkali /AHIR ratios are 1.4-2 times greater than in basaltic eucrites and are more variable; and the negative relation between K, Rb, Cs, and the alkali/AHIR ratio correlate with progressive alkali loss through volatile outgassing during crystallization of one or more magmas resulting in a greater than 90 percent loss of the volatile element inventory from the parent body. It is also detected that P displays volatile loss from the basaltic eucrites and elevated P/AHIR ratios in diogenites.

  8. Analysis of Moderately Siderophile Elements in Angrites: Implications for Core Formation of the Angrite Parent Body

    NASA Technical Reports Server (NTRS)

    Righter, K.; Shirai, N.; Irving, A.J.

    2009-01-01

    Angrites are an enigmatic group of achondrites, that constitute the largest group of basalts not affiliated with the Moon, Mars or Vesta (HEDs). Chemically, angrites are exceptionally refractory element- enriched (e.g., Al, Ca) and volatile element-depleted (e.g., Na and K) achondrites. Highly volatile siderophile and chalcophile elements (Zn, Ge and Se) may be less depleted than alkalis and Ga taken to imply a fractionation of plagiophile elements. Core formation on the angrite parent body (APB) is not well understood due to the dearth of moderately siderophile element (Ga, Ge, Mo, Sb, W) data for angrites, with the exception of Ni and Co [2]. In particular, there are no data for Mo abundances of angrites, while Sb and W abundances are reported for only 3 angrites, and have not always been determined on the same sample. The recent increase in angrite numbers (13) has greatly increased our knowledge of the compositional diversity of the angrite parent body (APB). In this study, we report new Co, Ni, Ga, Mo, Sb and W abundances for angrites by laser ablation inductively coupled plasma mass spectrometry (ICP-MS) in order to place constraints on core formation of the APB.

  9. Relationship of Blood Cholesterol to Body Composition, Physical Fitness, and Dietary Intake Measures in Third-Grade Children and Their Parents.

    ERIC Educational Resources Information Center

    Hopper, Chris A.; Gruber, Mary B.; Munoz, Kathy D.; MacConnie, Susan E.; Pfingston, Yvonne M.; Nguyen, Kim

    2001-01-01

    Investigated interrelationships between blood cholesterol levels, body composition, diet, and physical fitness among third graders and their parents. Data from blood and body measurements, children's physical fitness tests, parents' physical activity surveys, and children's and parents' dietary recalls highlighted significant mild-to-moderate…

  10. The longitudinal causal directionality between body image distress and self-esteem among Korean adolescents: the moderating effect of relationships with parents.

    PubMed

    Park, Woochul; Epstein, Norman B

    2013-04-01

    This study examined the longitudinal relationship between self-esteem and body image distress, as well as the moderating effect of relationships with parents, among adolescents in Korea, using nationally representative prospective panel data. Regarding causal direction, the findings supported bi-directionality for girls, but for boys the association was unidirectional, in that their self-esteem predicted body image distress, but not vice versa. A gender difference also emerged in the moderating effect of quality of relationships with parents. For girls, relationships with parents moderated the effect of body image distress on self-esteem, such that when relationships with parents were better, the effect of greater body image distress on subsequent lower self-esteem was stronger than when relationships with parents were less positive. For boys, relationships with parents moderated the influence of self-esteem on body image distress, such that self-esteem reduced body image distress more when boys had better relationships with parents.

  11. On the age and parent body of the daytime Arietids meteor shower

    NASA Astrophysics Data System (ADS)

    Abedin, A.; Wiegert, P.; Pokorny, P.; Brown, P.

    2016-01-01

    The daytime Arietid meteor shower is active from mid-May to late June and is among the strongest of the annual meteor showers, comparable in activity and duration to the Perseids and the Geminids. Due to the daytime nature of the shower, the Arietids have mostly been constrained by radar studies. The Arietids exhibit a long-debated discrepancy in the semi-major axis and the eccentricity of meteoroid orbits as measured by radar and optical surveys. Radar studies yield systematically lower values for the semi-major axis and eccentricity, where the origin of these discrepancies remain unclear. The proposed parent bodies of the stream include comet 96P/Machholz and more recently the Marsden's group of sun-skirting comets. In this work, we present detailed numerical modelling of the daytime Arietid meteoroid stream, with the goal to identifying the parent body and constraining the age of the stream. We use observational data from an extensive survey of the Arietids by the Canadian Meteor Orbit Radar (CMOR), in the period of 2002-2013, and several optical observations by the SonotaCo meteor network and the Cameras for All-sky Meteor Surveillance (CAMS). Our simulations suggest that the age and observed characteristics of the daytime Arietids are consistent with cometary activity from 96P, over the past 12000 years. The sunskirting comets that presumably formed in a major comet breakup between 100 - 950 AD (Chodas and Sekanina, 2005), alone, cannot explain the observed shower characteristics of the Arietids. Thus, the Marsden sunskirters cannot be the dominant parent, though our simulations suggest that they contribute to the core of the stream.

  12. Meteorite-asteroid spectral comparison - The effects of comminution, melting, and recrystallization

    NASA Technical Reports Server (NTRS)

    Clark, Beth E.; Fanale, Fraser P.; Salisbury, John W.

    1992-01-01

    The present laboratory simulation of possible spectral-alteration effects on the optical surface of ordinary chondrite parent bodies duplicated regolith processes through comminution of the samples to finer rain sizes. After reflectance spectra characterization, the comminuted samples were melted, crystallized, recomminuted, and again characterized. While individual spectral characteristics could be significantly changed by these processes, no combination of the alteration procedures appeared capable of affecting all relevant parameters in a way that improved the match between chondritic meteorites and S-class asteroids.

  13. A note on the prebiotic synthesis of organic acids in carbonaceous meteorites

    NASA Technical Reports Server (NTRS)

    Kerridge, John F.

    1991-01-01

    Strong similarities between monocarboxylic and hydrocarboxylic acids in the Murchison meteorite suggest corresponding similarities in their origins. However, various lines of evidence apparently implicate quite different precursor compounds in the synthesis of the different acids. These seeming inconsistencies can be resolved by postulating that the apparent precursors also share a related origin. Pervasive D enrichment indicates that this origin was in a presolar molecular cloud. The organic acids themselves were probably synthesized in an aqueous environment on an asteroidal parent body, the hydroxy (and amino) acids by means of the Strecker cyanohydrin reaction.

  14. Nuclear Effects of Supernova-Accelerated Cosmic Rays on Early Solar System Planetary Bodies

    NASA Astrophysics Data System (ADS)

    Meyer, B. S.; The, L.-S.; Johnson, J.

    2008-03-01

    The solar system apparently formed in the neighborhood of massive stars. Supernova explosions of these stars accelerate cosmic rays to 100s of TeVs. These cosmic rays could accelerate the beta decay of certain radioactive species in meteorite parent bodies.

  15. Identifying Meteorite Source Regions Through Near-Earth Object Spectroscopy

    NASA Astrophysics Data System (ADS)

    Thomas, Cristina A.; Binzel, R. P.

    2007-10-01

    By virtue of their landing on Earth, meteorites reside in near-Earth object (NEO) orbits prior to their arrival. Thus the population of observable NEOs most likely gives the best representation of meteorite source bodies. By linking meteorites to NEOs, and linking NEOs to their most likely main-belt source regions, we seek to gain insight into the original solar system sources for different meteorite classes. To forge the first link between meteorites and NEOs, we have developed a three dimensional method for quantitative comparisons between laboratory measurements of meteorites and telescopic measurements of near-Earth objects (NEOs). We utilize meteorite spectra from the Reflectance Experiment Laboratory (RELAB) database and NEO data from the SpeX instrument on the NASA IRTF. Using the Modified Gaussian Model (MGM) (Sunshine et al. 1993, JGR 98, 9075) as a mathematical tool (with no mineralogy interpretation), we treat asteroid and meteorite spectra identically in the calculation of 1-micron and 2-micron geometric band centers and their band area ratios (BARs). We fit the continuum as a linear function in wavenumber space. We choose to include the geometric center of the band in this study in order to examine the asymmetry of the bands. Using this numerical data we can examine the differences of the H, L, LL and HED meteorite classes. For each NEO spectrum, we assign a set of probabilities for it being related to each of these classes, yielding probability distributions for our NEO data set being related to H, L, LL, and HED meteorites. Our meteorite correlation distribution is then convolved with an NEO source region model (Bottke et al. 2002, Icarus 156, 399) to shed light on connections between these meteorite classes and their asteroid belt origins.

  16. Rapid planetesimal cooling after core formation: Pallasite meteorites

    NASA Astrophysics Data System (ADS)

    McKibbin, Seann; Ireland, Trevor; O'Neill, Hugh; Holden, Peter; Mallmann, Guilherme; Claeys, Philippe

    2016-04-01

    Pallasite meteorites consist of olivine-metal mixtures and accessory minerals (chromite, sulfide, phosphide, phosphate, phosphoran olivine) and represent core-mantle interaction zones in early differentiated planetesimals. They can be linked to five distinct planetesimals, indicating that they are default differentiation products, but their formation modes (deep, shallow, and impact environments) and age are elusive. Using new trace element, Cr isotope, and previously published datasets, we re-interpret some Main-group pallasites (low-MnO and high-FeO subgroups, e.g. Brenham and Springwater types respectively) as samples of core-mantle reaction zones. These meteorites host rounded olivine and near-solidus phosphate minerals, which record back-reaction of metal and silicate reservoirs during decreasing temperature after core formation and removal of primitive silicate melts. These phosphates form via late oxidation of phosphorus, which is siderophile at high temperature but lithophile at low temperature. Mn-Cr dates this event to before ~2.5 to 4 Myr after Solar System formation (range is model-dependent). Importantly, this is in agreement with Hf-W ages for very early metal-silicate (i.e. core-mantle) separation, but also indicates rapid planetesimal cooling within a few million years. Near-solidus silico-phosphate melts probably formed before most known planetesimal crusts (eucrite and angrite meteorites) and are among the earliest evolved planetary silicates. Similar phosphates in non-Main-Group pallasites from other parent bodies also suggest that core-mantle reaction zones are generic, datable features of differentiation. The absence of near-solidus phosphates in common cluster pallasites suggests that these were quenched from high temperature and are mechanical mixtures, rather than samples of genuine core-mantle boundaries.

  17. Fossilized diatoms in meteorites from recent falls in Sri Lanka

    NASA Astrophysics Data System (ADS)

    Hoover, Richard B.; Wallis, Jamie; Wickramarathne, Keerthi; Samaranayake, Anil; Williams, George; Jerman, Gregory; Wallis, D. H.; Wickramasinghe, N. C.

    2013-09-01

    On December 29, 2012, a bright yellow and green fireball was observed to disintegrate over the Polonnaruwa District of North Central, Sri Lanka. Many low density, black stones were recovered soon after the observed fall from rice paddy fields near the villages of Aralaganwila and Dimbulagala. These stones were initially studied by optical microscopy methods at the Medical Research Institute in Colombo, Sri Lanka. Soon thereafter, samples were sent to the UK and to the United States. More extensive Field Emission Scanning Electron Microscopy studies were then carried out at Cardiff University and the NASA/Marshall Space Flight Center. The physico-chemical properties, elemental abundances, mineralogy and stable isotope data clearly indicate that these stones are non-terrestrial. Freshly fractured interior surfaces of the black stones have also been observed to contain the remains of fossilized diatom. Many of the diatom frustules are clearly embedded in the meteorite rock matrix and exhibit nitrogen levels below the EDX detection limits. Some of the fossil diatoms are araphid marine pennates and planktonic forms that are inconsistent with conditions associated with rice paddy fields. These observations indicate the fossilized diatoms are indigenous to the meteorites rather than post-arrival biological contaminants. The carbon content and mineralogy suggests that these stones may represent a previously ungrouped clan of carbonaceous meteorites. The extremely low density (~0.6) of the stones and their observed mineralogy was inconsistent with known terrestrial rocks (e.g., pumice, diatomite and fulgurites). The minerals detected suggest that the parent body of the Polonnaruwa stones may have been the nucleus of a comet. These observations are interpreted as supporting the Hoyle-Wickramasinghe Panspermia hypothesis and the hypothesis that diatoms and other microorganisms might be capable of living and growing in water ice and brines in comets.

  18. An ion microprobe study of CAIs from CO3 meteorites. [Abstract only

    NASA Technical Reports Server (NTRS)

    Russell, S. S.; Greenwood, R. C.; Fahey, A. J.; Huss, G. R.; Wasserburg, G. J.

    1994-01-01

    When attempting to interpret the history of Ca, Al-rich inclusions (CAIs) it is often difficult to distinguish between primary features inherited from the nebula and those produced during secondary processing on the parent body. We have undertaken a systematic study of CAIs from 10 CO chondrites, believed to represent a metamorphic sequence with the goal of distinguishing primary and secondary features. ALHA 77307 (3.0), Colony (3.0), Kainsaz (3.1), Felix (3.2), ALH 82101 (3.3), Ornans (3.3), Lance (3.4), ALHA 77003 (3.5), Warrenton (3.6), and Isna (3.7) were examined by Scanning Electron Microscopy (SEM) and optical microscopy. We have identified 141 CAIs within these samples, and studied in detail the petrology of 34 inclusions. The primary phases in the lower petrologic types are spinel, melilite, and hibonite. Perovskite, FeS, ilmenite, anorthite, kirschsteinite, and metallic Fe are present as minor phases. Melilite becomes less abundant in higher petrologic types and was not detected in chondrites of type 3.5 and above, confirming previous reports that this mineral easily breaks down during heating. Iron, an element that would not be expected to condense at high temperatures, has a lower abundance in spinel from low-petrologic-type meteorites than those of higher grade, and CaTiO3 is replaced by FeTiO3 in meteorites of higher petrologic type. The abundance of CAIs is similar in each meteorite. Eight inclusions have been analyzed by ion probe. The results are summarized. The results obtained to date show that CAIs in CO meteorites, like those from other meteorite classes, contain Mg* and that Mg in some inclusions has been redistributed.

  19. Meteoritic Constraints on Models of the Solar Nebula: The Abundances of Moderately Volatile Elements

    NASA Technical Reports Server (NTRS)

    Cassen, P.; Cuzzi, Jeffrey N. (Technical Monitor)

    1994-01-01

    The "moderately volatile" elements are those which condense (or evaporate) in the temperature range 650 - 1350 K, as a mix of material with solar abundances is cooled (or heated) under equilibrium conditions. Their relative abundances in chondritic meteorites are solar (or "cosmic", as defined by tile composition of CI meteorites) to within a factor of several, but vary within that range in a way that correlates remarkably well with condensation temperature, independent of chemical affinity. It has been argued that this correlation reflects a systematically selective process which favored the accretion of refractory material over volatile material from a cooling nebula. Wasson and Chou suggested that condensation and settling of solids contemporaneously with the cooling and removal of nebular gas could produce tile observed abundance patterns, but a quantitative model has been lacking. We show that the abundance patterns of the moderately volatile elements in chondritic meteorites can be produced, in some degree of quantitative detail, by models of the solar nebula that are designed to conform to observations of T Tauri stars and the global conservation laws. For example, even if the local surface density of the nebula is not decreasing, condensation and accretion of solids from radially inflowing gas in a cooling nebula can result in depletions of volatiles, relative to refractories, like those observed. The details of the calculated abundance patterns depend on (but are not especially sensitive to) model parameters, and can exhibit the variations that distinguish the meteorite classes. Thus it appears that nebula characteristics Such as cooling rates, radial flow velocities, and particle accumulation rates can be quantitatively constrained by demanding that they conform to meteoritic data; and the models, in turn, can produce testable hypotheses regarding the time and location of the formation of the chondrite parent bodies and the planets.

  20. The mineralogy of meteorites.

    NASA Technical Reports Server (NTRS)

    Mason, B.

    1972-01-01

    Of particular interest among minerals recently discovered in meteorites are five phosphate minerals, three of them unknown in terrestrial rocks; a chromium nitride and a silicon oxynitride; lonsdaleite and chaoite, new polymorphs of carbon; ringwoodite and majorite, the spinel and garnet analogs of olivine and pyroxene, respectively; a number of calcium- and aluminum-rich silicates in the Allende meteorite, a type III carbonaceous chondrite which fell in 1969; and several alkali-rich silicates found as inclusions in iron meteorites. Knowledge of the compositional range of the common minerals olivine, pyroxene, and plagioclase has also been greatly increased by recent researches.

  1. Radiocarbon datings of Yamato meteorites

    NASA Technical Reports Server (NTRS)

    Kigoshi, K.; Matsuda, E.

    1986-01-01

    The terrestrial ages of five Yamato Meteorites were measured by the content of cosmic-ray-produced carbon-14. Three Yamato Meteorites Y-74013, Y-74097, and Y-74136, which are all diogenites, were found at sites from one to two kilometers apart from each other. Evidence is presented for these three meteorites being a single meteorite. Also presented is a method adopted in the experimental procedure which includes a check for modern carbon contamination in the meteorites.

  2. Density and Porosity of Shower Meteorites as Indicators of Meter-scale Asteroid Homogeneity

    NASA Astrophysics Data System (ADS)

    Macke, Robert; Britt, D.; Consolmagno, G.

    2008-09-01

    Meteorite showers containing multiple stones from the same event provide clues to the homogeneity of meteorite parent bodies over decimeter to meter scales. Small bodies that have been studied in detail show a high degree of surface mineralogical homogeneity in reflectance spectra (Abe et al., 2006a; Veverka et al., 2001) and no detectable large scale density variations (Abe et al., 2006b; Thomas et al., 2002). Large meteorite showers provide a direct sample of the possible variations in physical properties of small bodies. We present the results of density, porosity, and magnetic susceptibility measurements of at least ten stones each from seven meteorite showers in the collection at the Smithsonian Institution's National Museum of Natural History. This includes three carbonaceous chondrites (Allende, Murchison and Murray) and four ordinary chondrites. We find strong homogeneity within showers. For example, the mass-weighted average grain density of Allende we measured as 3.60 g/cm3, with individual stones ranging from 3.59 to 3.62 g/cm3 and typical uncertainties 0.03 or 0.04 g/cm3. Allende porosities averaged 18.8% and ranged from 17.8% to 19.5% with typical uncertainties of about 1.2%. We also studied one weathered find (Gold Basin) for clues regarding the uniformity of chondrite weathering. For five showers, we compare results with measurements made on additional stones at the Vatican Observatory and the American Museum of Natural History. This work was supported in part by a Smithsonian Institution Graduate Student Fellowship. Veverka, J. et al., 2001. Science 289, 2088. Abe S. et al., 2006b. Science 312, 1344. Abe M. et al., 2006a. Science 312, 1334. Thomas P. et al., 2002. Icarus 155, 18.

  3. Transgenerational Effects of Parental Larval Diet on Offspring Development Time, Adult Body Size and Pathogen Resistance in Drosophila melanogaster

    PubMed Central

    Valtonen, Terhi M.; Kangassalo, Katariina; Pölkki, Mari; Rantala, Markus J.

    2012-01-01

    Environmental conditions experienced by parents are increasingly recognized to affect offspring performance. We set out to investigate the effect of parental larval diet on offspring development time, adult body size and adult resistance to the bacterium Serratia marcescens in Drosophila melanogaster. Flies for the parental generation were raised on either poor or standard diet and then mated in the four possible sex-by-parental diet crosses. Females that were raised on poor food produced larger offspring than females that were raised on standard food. Furthermore, male progeny sired by fathers that were raised on poor food were larger than male progeny sired by males raised on standard food. Development times were shortest for offspring whose one parent (mother or the father) was raised on standard and the other parent on poor food and longest for offspring whose parents both were raised on poor food. No evidence for transgenerational effects of parental diet on offspring disease resistance was found. Although paternal effects have been previously demonstrated in D. melanogaster, no earlier studies have investigated male-mediated transgenerational effects of diet in this species. The results highlight the importance of not only considering the relative contribution each parental sex has on progeny performance but also the combined effects that the two sexes may have on offspring performance. PMID:22359607

  4. Neutron capture production rates of cosmogenic 60Co, 59Ni and 36Cl in stony meteorites

    NASA Technical Reports Server (NTRS)

    Spergel, M. S.; Reedy, R. C.; Lazareth, O. W.; Levy, P. W.

    1986-01-01

    Results for neutron flux calculations in stony meteoroids (of various radii and compositions) and production rates for Cl-36, Ni-59, and Co-60 are reported. The Ni-59/Co-60 ratio is nearly constant with depth in most meteorites: this effect is consistent with the neutron flux and capture cross section properties. The shape of the neutron flux energy spectrum, varies little with depth in a meteorite. The size of the parent meteorite can be determined from one of its fragments, using the Ni-59/Co-60 ratios, if the parent meteorite was less than 75 g/cm(2) in radius. If the parent meteorite was larger, a lower limit on the size of the parent meteorite can be determined from a fragment. In C3 chondrites this is not possible. In stony meteorites with R less than 50 g/cm(2) the calculated Co-60 production rates (mass less than 4 kg), are below 1 atom/min g-Co. The highest Co-60 production rates occur in stony meteorites with radius about 250 g/cm(2) (1.4 m across). In meteorites with radii greater than 400 g/cm(2), the maximum Co-60 production rate occurs at a depth of about 175 g/cm(2) in L-chondrite, 125 g/cm(2) in C3 chrondrite, and 190 g/cm(2) in aubrites.

  5. The Nakhla Martian Meteorite is a Cumulate Igenous Rock. Comment on "Glass-Bearing Inclusions in Nakhla (SNC Meteorite) Augite: Heterogeneously Trapped Phases"

    NASA Technical Reports Server (NTRS)

    Treiman, A. H.

    2003-01-01

    All the properties of the Nakhla Martian meteorite suggest that it is a cumulate igneous rock, formed from a basaltic parental magma. Anomalous magmatic inclusions in Nakhla s augite grains can be explained by disequilibrium processes during crystal growth, and have little significance in the geological history of the meteorite.

  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. Expected Geochemical and Mineralogical Properties of Meteorites from Mercury: Inferences from Messenger Data

    NASA Technical Reports Server (NTRS)

    McCubbin, F. M.; McCoy, T. J.

    2016-01-01

    Meteorites from the Moon, Mars, and many types of asteroid bodies have been identified among our global inventory of meteorites, however samples of Mercury and Venus have not been identified. The absence of mercurian and venusian meteorites could be attributed to an inability to recognize them in our collections due to a paucity of geochemical information for Venus and Mercury. In the case of mercurian meteorites, this possibility is further supported by dynamical calculations that suggest mercurian meteorites should be present on Earth at a factor of 2-3 less than meteorites from Mars [1]. In the present study, we focus on the putative mineralogy of mercurian meteorites using data obtained from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft, which has provided us with our first quantitative constraints on the geochemistry of planet Mercury. We have used the MESSENGER data to compile a list of mineralogical and geochemical characteristics that a meteorite from Mercury is likely to exhibit.

  8. Oxygen Isotope Compositions of the Kaidun Meteorite - Indications for Aqeuous Alteration of E-Chondrites

    NASA Technical Reports Server (NTRS)

    Ziegler, K.; Zolensky, M.; Young, E. D.; Ivanov, A.

    2012-01-01

    The Kaidun microbreccia is a unique meteorite due to the diversity of its constituent clasts. Fragments of various types of carbonaceous (CI, CM, CV, CR), enstatite (EH, EL), and ordinary chondrites, basaltic achondrites, and impact melt products have been described, and also several unknown clasts [1, and references therein]. The small mm-sized clasts represent material from different places and times in the early solar system, involving a large variety of parent bodies [2]; meteorites are of key importance to the study of the origin and evolution of the solar system, and Kaidun is a collection of a range of bodies evidently representing samples from across the asteroid belt. The parent-body on which Kaidun was assembled is believed to be a C-type asteroid, and 1-Ceres and the martian moon Phobos have been proposed [1-4]. Both carbonaceous (most oxidized) and enstatite (most reduced) chondrite clasts in Kaidun show signs of aqueous alterations that vary in type and degree and are most likely of pre-Kaidun origin [1, 4].

  9. Meteorite and meteoroid: New comprehensive definitions

    USGS Publications Warehouse

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

    2010-01-01

    Meteorites have traditionally been defined as solid objects that have fallen to Earth from space. This definition, however, is no longer adequate. In recent decades, man-made objects have fallen to Earth from space, meteorites have been identified on the Moon and Mars, and small interplanetary objects have impacted orbiting spacecraft. Taking these facts and other potential complications into consideration, we offer new comprehensive definitions of the terms "meteorite,""meteoroid," and their smaller counterparts: A meteoroid is a 10-??m to 1-m-size natural solid object moving in interplanetary space. A micrometeoroid is a meteoroid 10 ??m to 2 mm in size. A meteorite is a natural, solid object larger than 10 ??m in size, derived from a celestial body, that was transported by natural means from the body on which it formed to a region outside the dominant gravitational influence of that body and that later collided with a natural or artificial body larger than itself (even if it is the same body from which it was launched). Weathering and other secondary processes do not affect an object's status as a meteorite as long as something recognizable remains of its original minerals or structure. An object loses its status as a meteorite if it is incorporated into a larger rock that becomes a meteorite itself. A micrometeorite is a meteorite between 10 ??m and 2 mm in size. Meteorite- "a solid substance or body falling from the high regions of the atmosphere" (Craig 1849); "[a] mass of stone and iron that ha[s] been directly observed to have fallen down to the Earth's surface" (translated from Cohen 1894); "[a] solid bod[y] which came to the earth from space" (Farrington 1915); "A mass of solid matter, too small to be considered an asteroid; either traveling through space as an unattached unit, or having landed on the earth and still retaining its identity" (Nininger 1933); "[a meteoroid] which has reached the surface of the Earth without being vaporized" (1958

  10. FRIPON, a French fireball network for the recovery of both fresh and rare meteorite types

    NASA Astrophysics Data System (ADS)

    Colas, F.; Zanda, B.; Bouley, S.; Vernazza, P.; Gatacceca, J.; Vaubaillon, J.; Marmot, C.; Kwon, M.; Audureau, Y.; Rotaru, M.

    2014-07-01

    The meteorite fall rate over a territory the size of France must be somewhere between 5 and 25/yr [1], most likely closer to the higher number if we consider recent works on Chelyabinsk event [2]. Most meteorites presently in collections are ''finds'' (as opposed to ''falls''), i.e. meteorites found a significant amount of time after their fall, often weathered from being exposed to terrestrial alteration, which makes them scientifically less valuable. Some of the most precious meteorites, which have not been significantly heated on their parent-body and have chemical compositions closest to that of the Sun (CI chondrites --- such as Orgueil, which fell in France in 1864, and CM chondrites --- such as Murchison and Paris), also happen to be the most fragile ones. It is thus essential that meteorites be collected shortly after they fall, ideally within a few days. This was frequently the case in the 19th century, at least in France, where 45 witnessed falls were recovered, amounting to almost one tenth for actual falls. The goal of the FRIPON network is to measure accurate orbit in order to pinpoint the parents bodies. This work will not only be done for the few meteorite falls but also for all the bright meteors, we hope to get about one thousand of accurate orbits per year. The idea is to search for meteorite streams as it is done for meteoroids. It will be far more easy to associate a single meteorite orbit with a stream of objects and perhaps a parent body. The FRIPON project was approved by the National Research Agency (ANR) in July 2013. The funding received will allow us to cover the whole French territory with ''Fish Eye'' cameras and radio receivers of GRAVES radar signal. We made an extensive test of hardware (camera and lens). The hardware used in the previous network was mainly based on analogical devices with fixed parameters whereas new digital cameras allow a change of acquisition parameters in real time. So it is now possible to observe during day

  11. Fracture Characterization of Meteorites

    NASA Astrophysics Data System (ADS)

    Bryson, K. L.; Agrawal, P.; Ostrowski, D. R.; Sears, D. W. G.

    2015-07-01

    NASA ARC has been tasked with understanding the behavior of ~100m asteroids entering the atmosphere and quantifying the impact hazard. As part of this task, we report the initial results of a survey of the fracture properties of meteorites.

  12. Antimony in iron meteorites

    NASA Technical Reports Server (NTRS)

    Willis, J.

    1981-01-01

    Sb concentrations determined by radiochemical neutron activation analysis in 60 iron meteorites range from 0.2 ng/g to 36 microg/g. The meteorites with the highest Sb concentrations are those of the nonmagmatic groups IAB and IIICD, while meteorites with the lowest Sb concentrations are found in groups IVA and IVB. In all groups Sb is positively correlated with Ni; slopes on log Sb vs log Ni plots decrease with increasing Ni. This decrease may reflect an increasing tendency to avoid schreibersite during the analysis of high-Ni meteorites because Sb partitions strongly into schreibersite. It is found that schreibersite from New Westville is enriched in Cr, Ni, Ge, As, Sb, and Au and depleted in Fe, Co, Ir; the Sb content in schreibersite is 540 times higher than the bulk metal value.

  13. Effects of parental and dietary PCBs on survival, growth, and body burdens of larval striped bass

    SciTech Connect

    Westin, D.T.; Olney, C.E.; Rogers, B.A.

    1983-01-01

    The relative contribution of parental and dietary sources of PCBs on the effects on survival and growth of striped bass larvae during their first month of life was investigated. Larvae of known PCBs body burden were fed for 20 days on ARTEMIA diets containing high and low concentrations of PCBs. The inherited and dietary concentrations had no effect on survival and growth after yolk absorption. Residue analysis of eggs and larvae showed a consistent reduction of PCBs concentration over time regardless of the PCBs level in the diet. The reduction in total PCBs reflects dilution of PCB from paretal sources by the accretion of relatively uncontaminated tissue during the period of rapid larval growth. (JMT)

  14. Proceedings of a workshop on Differences Between Antarctic and Non-Antarctic Meteorites

    NASA Technical Reports Server (NTRS)

    Koeberl, Christian (Editor); Cassidy, William A. (Editor)

    1989-01-01

    The known facts, together with new research results are reviewed, in order to examine apparent differences between the Antarctic and non-Antarctic populations. In view of the statistically significant number of Antarctic meteorites, and the existence of rare or previously unknown types of meteorites among the Antarctic meteorite collection, the question was really not so much whether there are differences, but to define which ones are significant and what their origin is. Two main causes for the possible differences have been suggested previously, namely differences in the meteorite parent populations and secondary effects (e.g., weathering). The workshop was structured to contain sessions on chemical, isotopic, petrological, and mineralogical studies of meteorites from the two collections; terrestrial age determinations; discussions on mass frequency distributions; relative abundances of meteorite types; and terrestrial meteorite flux rates and their possible changes with time.

  15. Meteorite Seymchan structure

    NASA Astrophysics Data System (ADS)

    Hontsova, S. S.; Petrova, E. V.; Muftahetdinova, R. F.; Chulanova, V. N.; Grokhovsky, V. I.

    2016-09-01

    The meteorite Seymchan specimen was studied using optical microscopy and scanning electron microscopy. Olivine grains have roundish shapes, which was formed during matter cooling. Different features of the metal structure such as plessite structure and Neimann bands were observed. The oxide edges were observed in the boundaries between phases. The oxides were formed in the terrestrial conditions. The boundary regions between metal and olivine in the meteorite contain grains of troilite, schreibersite, and chromite.

  16. Meteorites: messengers from the early solar system.

    PubMed

    Hofmann, Beda A

    2010-01-01

    Meteorites are fragments from solar system bodies, dominantly asteroids. A small fraction is derived from the Moon and from Mars. These rocks tell a rich history of the early solar system and range from solids little changed since the earliest phases of solid matter condensation in the solar nebula (chondrites) to material representing asteroidal metamorphism and melting, impact processes on the Moon and even aqueous alteration near the surface of Mars. Meteorites are very rare. Currently many meteorites result from searches in Antarctica and the hot deserts of North Africa and Arabia. The present high find rate likely represents a unique short-term event, asking for a careful management of this scarce scientific resource.

  17. Meteorites: messengers from the early solar system.

    PubMed

    Hofmann, Beda A

    2010-01-01

    Meteorites are fragments from solar system bodies, dominantly asteroids. A small fraction is derived from the Moon and from Mars. These rocks tell a rich history of the early solar system and range from solids little changed since the earliest phases of solid matter condensation in the solar nebula (chondrites) to material representing asteroidal metamorphism and melting, impact processes on the Moon and even aqueous alteration near the surface of Mars. Meteorites are very rare. Currently many meteorites result from searches in Antarctica and the hot deserts of North Africa and Arabia. The present high find rate likely represents a unique short-term event, asking for a careful management of this scarce scientific resource. PMID:21138163

  18. Where Did the Ureilite Parent Body Accrete? Constraints from Chemical and Isotopic Compositions

    NASA Astrophysics Data System (ADS)

    Goodrich, Cyrena; O'Brien, David P.

    2014-11-01

    Almahata Sitta and other polymict ureilites contain a remarkable diversity of materials, including EH, EL, OC, R- and CB chondrites, in addition to the dominant ureilitic material [1]. These materials represent at least 6 different parent asteroids and a wide range of chemical and isotopic environments in the early Solar System. To understand the origin of this diversity it is critical to know where (heliocentric distance) the ureilite parent body (UPB) accreted. The chemical and isotopic compositions of ureilite precursors (inferred from the compositions of ureilites) can provide clues. Lithophile element ratios such as Si/Mg and Mn/Mg [2,3], and deficits in neutron-rich Cr, Ti and Ni isotopes [3], indicate that ureilite precursors were similar to ordinary or enstatite chondrites (OC or EC), not carbonaceous chondrites (CC). In contrast, high carbon contents, carbon isotopes and oxygen isotopes suggest a genetic link to CC. This poses a conundrum considering the variation of asteroid types, which suggests that EC and OC dominate the inner asteroid belt and CC the outer belt. However, the CC-like oxygen isotopes of ureilites strongly suggest the effects of parent-body aqueous alteration [4,5], which clearly implies that the UPB accreted beyond the ice line. Lithophile element properties of ureilites compared with chondrites may not be a reliable indicator of location of accretion, because lithophile elements in chondrites are sited mainly in chondrules and the UPB accreted before most chondrules formed [6]. Ureilite Cr, Ti and Ni isotopes may indicate late introduction of the neutron rich isotopes of these elements to the CC-formation region [7]. We conclude that the UPB accreted in the outer belt, like CC. The UPB or one of its offspring must have migrated to the inner belt to acquire OC, EC and R-chondrite materials.[1] Horstmann M. & Bischoff A. [2014] Chemie der Erde 74, 149.[2] Goodrich C. [1999] MAPS 34, 109.[3] Warren P. [2011] GCA 46, 53.[4] Young E. [1999

  19. AMINO ACID ANALYSES OF THE ANTARCTIC CM2 METEORITES ALH 83100 AND LEW 90500 USING LIQUID CHROMATOGRAPHY-TIME OF FLIGHT-MASS SPECTROMETRY

    NASA Technical Reports Server (NTRS)

    Glavin, D. P.; Dworkin, J. P.; Aubrey, A.; Botta, O.; Doty, J. H., III; Bada, J. L.

    2001-01-01

    The investigation of organic compounds in primitive carbonaceous meteorites provides a record of the chemical processes that occurred in the early solar system. In particular, amino acids have been shown to be potential indicators in tracing the nature of carbonaceous chondrite parent bodies [ 13. The delivery of amino acids by carbonaceous chondrites to the early Earth could have been any important source of the Earth's prebiotic organic inventory [2]. Over 80 different amino acids have been detected in the Murchison CM2 meteorite, most of them completely non-existent in the terrestrial biosphere [3]. We have optimized a new liquid chromatography-time-of-flight-mass spectrometry (LC-ToF-MS) technique coupled with OPAMAC derivatization in order to detect amino acids in meteorite extracts by UV fluorescence and exact mass simultaneously. The detection limit of the LC-ToF-MS instrument for amino acids is at least 3 orders of magnitude lower than traditional GC-MS techniques. Here we report on the first analyses of amino acids and their enantiomeric abundances in the CM2 carbonaceous meteorites ALH 83100, LEW 90500, and Murchison using this new LC-ToF-MS instrument configuration. Amino acid analyses of any kind for the CM meteorite ALH 83100 have not previously been reported.

  20. Mechanical properties of several Fe-Ni meteorites

    SciTech Connect

    Mulford, Roberta N; El - Dasher, Bassem

    2010-10-28

    The strength and elastic constants of meteorites are of increasing interest as predictions of meteorite impacts on earth come within the realm of possibility. In addition, meteorite impacts on extraterrestrial bodies provide an excellent sampling tool for evaluation of planetary compositions and properties. Fe-Ni meteorites provide a well-defined group of materials of fairly uniform composition. Iron-nickel meteorites exhibit a unique lamellar microstructure, a Widmanstatten structure, consisting of small regions with steep-iron-nickel composition gradients. This microstructure is found in the Fe-Ni system only in meteorites, and is believed to arise as a result of slow cooling in a planetary core or other large mass. Meteorites with compositions consisting of between 5 and 17% nickel in iron are termed 'octahedrite,' and further characterized according to the width of the Ni-poor kamacite bands; 'fine,' (0.2-0.5 mm) 'medium,' (0.5-1.3 mm) and 'coarse,' (1.5-3.3 mm). Many meteorites have inclusions and structures indicating that the material has been shocked at some point early in its evolution. Several Iron-nickel meteorites have been examined using Vickers and spherical indentation, x-ray fluorescence, and EBSD. Direct observation of mechanical properties in these highly structured materials provides a valuable supplement to bulk measurements, which frequently exhibit large variation in dynamic properties, even within a single sample. Previous studies of the mechanical properties of a typical iron-nickel meteorite, a Diablo Canyon specimen, indicated that the strength of the composite was higher by almost an order of magnitude than values obtained from laboratory-prepared specimens. Additional meteorite specimens have been examined to establish a range of error on the previously measured yield, to determine the extent to which deformation upon re-entry contributes to yield, and to establish the degree to which the strength varies as a function of microstructure.

  1. Chemical and mineralogical size segregation in the impact disruption of anhydrous stone meteorites

    SciTech Connect

    Flynn, G.J.; Durda, D.D.

    2005-02-02

    We performed impact disruption experiments on pieces from eight different anhydrous chondritic meteorites - four weathered ordinary chondrite finds from North Africa (NWA791, NWA620, NWA869 and MOR001), three almost unweathered ordinary chondrite falls (Mbale, Gao, and Saratov), and an almost unweathered carbonaceous chondrite fall (Allende). In each case the impactor was a small (1/8 or 1/4 in) aluminum sphere fired at the meteorite target at {approx} 5 km/s, comparable to the mean collision speed in the main-belt. Some of the {approx}5 to {approx} 150 {micro}m debris from each disruption was collected in aerogel capture cells, and the captured particles were analyzed by in situ synchrotron-based X-ray fluorescence. For each meteorite, many of the smallest particles (< 10 {micro}m up to 35 {micro}m in size, depending on the meteorite) exhibit very high Ni/Fe ratios compared to the Ni/Fe ratios measured in the larger particles (> 45 {micro}m), a composition consistent with the smallest debris being dominated by matrix material while the larger debris is dominated by fragments from olivine chondrules. These results may explain why the {approx} 10 {micro}m interplanetary dust particles (IDPs) collected from the Earth's stratosphere are C-rich and volatile-rich compared to the presumed solar nebula composition. The {approx} 10 {micro}m IDPs may simply sample the matrix of an inhomogeneous parent body, structurally and mineralogically similar to the chondritic meteorites, which are inhomogeneous assemblages of compact, strong, C- and volatile-poor chondrules that are distributed in a more porous, C- and volatile-rich matrix. In addition, these results may explain why the micrometeorites, which are {approx} 50 {micro}m to millimeters in size, recovered from the polar ices are Ni- and S-poor compared to chondritic meteorites, since these polar micrometeorites may preferentially sample fragments from the Ni- and S-poor olivine chondrules. These results indicate that the

  2. (U-Th)/He Dating of Martian Meteorites: Shock Temperature Conditions Revisited

    NASA Astrophysics Data System (ADS)

    Min, K. K.

    2013-12-01

    Shock impact is one of the most prominent dynamic events to have occurred after the formation of any planetary bodies in our solar system. This near-surface episode caused an instantaneous temperature increase in the impact site and ejected materials, and was followed by a rapid cooling. Constraining shock P-T conditions and post-shock cooling paths of meteorites is crucial to understanding ejection dynamics, evaluating pre-shock features in the meteorites, and testing the possible transfer of viable life to different planets. Tremendous efforts have been devoted to studying the physical conditions of the shock events, and the most established method to constrain shock pressure condition is to compare microscopic textures of meteorites with those of artificially shocked terrestrial rocks. Using the equation of state, the shock pressures can be converted to corresponding 'post-shock temperatures (Tpost-shock),' which represent temperature increases (ΔT) during the shock relative to the pre-shock temperatures. The Tpost-shock can be further converted to Tpeak if the pre-shock temperature for an individual meteorite is known (Tpeak = Tpost-shock - Tpre-shock). An alternative way to estimate the shock T conditions is to use (U-Th)/He system whose sensitivity to temperature is relatively high. This approach can provide the absolute temperature conditions (Tpeak) of the shock event, instead of the T increases (ΔT). This method requires thermal modeling using the following input parameters: (1) pre-atmospheric body radius, (2) depth of a sample from the surface of the parent meteoroid, (3) surface temperature of meteoroid, (4) thermal diffusivity, (5) activation energy and pre-exponential term for He diffusion in merrillite, and (6) diffusion domain size. Most of these input parameters, except the diffusion domain size, are relatively well constrained for Martian meteorites, and uncertainties associated with these parameters have a limited effect on the Tpeak estimates

  3. Meteorite and meteoroid: New comprehensive definitions

    NASA Astrophysics Data System (ADS)

    Rubin, Alan E.; Grossman, Jeffrey N.

    2010-01-01

    Meteorites have traditionally been defined as solid objects that have fallen to Earth from space. This definition, however, is no longer adequate. In recent decades, man-made objects have fallen to Earth from space, meteorites have been identified on the Moon and Mars, and small interplanetary objects have impacted orbiting spacecraft. Taking these facts and other potential complications into consideration, we offer new comprehensive definitions of the terms ``meteorite,''``meteoroid,'' and their smaller counterparts: A meteoroid is a 10-μm to 1-m-size natural solid object moving in interplanetary space. A micrometeoroid is a meteoroid 10μm to 2mm in size. A meteorite is a natural, solid object larger than 10μm in size, derived from a celestial body, that was transported by natural means from the body on which it formed to a region outside the dominant gravitational influence of that body and that later collided with a natural or artificial body larger than itself (even if it is the same body from which it was launched). Weathering and other secondary processes do not affect an object's status as a meteorite as long as something recognizable remains of its original minerals or structure. An object loses its status as a meteorite if it is incorporated into a larger rock that becomes a meteorite itself. A micrometeorite is a meteorite between 10μm and 2mm in size.Meteorite-``a solid substance or body falling from the high regions of the atmosphere'' (Craig 1849); ``[a] mass of stone and iron that ha[s] been directly observed to have fallen down to the Earth's surface'' (translated from Cohen 1894); ``[a] solid bod[y] which came to the earth from space'' (Farrington 1915); ``A mass of solid matter, too small to be considered an asteroid; either traveling through space as an unattached unit, or having landed on the earth and still retaining its identity'' (Nininger 1933); ``[a meteoroid] which has reached the surface of the Earth without being vaporized'' (1958

  4. Chelyabinsk meteorite explains unusual spectral properties of Baptistina Asteroid Family

    NASA Astrophysics Data System (ADS)

    Reddy, Vishnu; Sanchez, Juan A.; Bottke, William F.; Cloutis, Edward A.; Izawa, Matthew R. M.; O'Brien, David P.; Mann, Paul; Cuddy, Matthew; Le Corre, Lucille; Gaffey, Michael J.; Fujihara, Gary

    2014-07-01

    We investigated the spectral and compositional properties of Chelyabinsk meteorite to identify its possible parent body in the main asteroid belt. Our analysis shows that the meteorite contains two spectrally distinct but compositionally indistinguishable components of LL5 chondrite and shock blackened/impact melt material. Our X-ray diffraction analysis confirms that the two lithologies of the Chelyabinsk meteorite are extremely similar in modal mineralogy. The meteorite is compositionally similar to LL chondrite and its most probable parent asteroid in the main belt is a member of the Flora family. Our work confirms previous studies (e.g., Vernazza et al. [2008]. Nature 454, 858-860; de León, J., Licandro, J., Serra-Ricart, M., Pinilla-Alonso, N., Campins, H. [2010]. Astron. Astrophys. 517, A23; Dunn, T.L., Burbine, T.H., Bottke, W.F., Clark, J.P. [2013]. Icarus 222, 273-282), linking LL chondrites to the Flora family. Intimate mixture of LL5 chondrite and shock blackened/impact melt material from Chelyabinsk provides a spectral match with (8) Flora, the largest asteroid in the Flora family. The Baptistina family and Flora family overlap each other in dynamical space. Mineralogical analysis of (298) Baptistina and 11 small family members shows that their surface compositions are similar to LL chondrites, although their absorption bands are subdued and albedos lower when compared to typical S-type asteroids. A range of intimate mixtures of LL5 chondrite and shock blackened/impact melt material from Chelyabinsk provides spectral matches for all these BAF members. We suggest that the presence of a significant shock/impact melt component in the surface regolith of BAF members could be the cause of lower albedo and subdued absorption bands. The conceptual problem with part of this scenario is that impact melts are very rare within ordinary chondrites. Of the ∼42,000 ordinary chondrites, less than 0.5% (203) of them contain impact melts. A major reason that impact

  5. Basaltic volcanism on the eucrite parent body - Petrology and chemistry of the polymict eucrite ALHA80102

    NASA Technical Reports Server (NTRS)

    Treiman, A. H.; Drake, M. J.

    1985-01-01

    The polymict eucrite meteorite ALHA80102 is an unequilibrated breccia of basaltic and gabbroic clasts in a fragmental matrix. Clasts include basalts of many textural types, cumulate gabbro, black 'glass', and ferroan troctolite (plagioclase, silica, Fe-rich olivine, ilmenite, mesostasis). Ferroan troctolite has not been previously reported from eucrites or howardites; it is interpreted as the end-product of fractional crystallization of eucritic magmas. Bulk and trace element compositions (by electron microprobe and INAA) of clasts and matrix from ALHA80102 are similar to those of other eucrites; the meteorite contains clasts similar to Juvinas and to Stannern. A clast of cumulate eucrite gabbro is enriched in the light rare earths (La/Lu = 2XCI). This clast is interpreted as an unrepresentative sample of metamorphically equilibrated gabbro; LREE-enriched magmas need not be invoked. ALHA80102 is similar to other polymict eucrites from the Allan Hills and may be paired with ALHA76005, ALHA77302, and ALHA78040.

  6. Northwest Africa 8535 and Northwest Africa 10463: New Insights into the Angrite Parent Body

    NASA Technical Reports Server (NTRS)

    Santos, A. R.; Agee, C. B.; Shearer, C. K.; McCubbin, F. M.

    2016-01-01

    The angrite meteorites are valuable samples of igneous rocks formed early in Solar System history (approx.4.56 Ga, summarized in [1]). This small meteorite group (approx.24 individually named specimens) consists of rocks with somewhat exotic mineral compositions (e.g., high Ca olivine, Al-Ti-bearing diopside-hedenbergite, calcium silico-phosphates), resulting in exotic bulk rock compositions. These mineral assemblages remain fairly consistent among angrite samples, which suggests they formed due to similar processes from a single mantle source. There is still debate over the formation process for these rocks (see summary in [1]), and analysis of additional angrite samples may help to address this debate. Toward this end, we have begun to study two new angrites, Northwest Africa 8535, a dunite, and Northwest Africa 10463, a basaltic angrite.

  7. Meteorites - The Significance of Collection and Curation and Future Developments

    NASA Astrophysics Data System (ADS)

    Smith, Caroline

    2015-03-01

    Meteorites are some of the most important and valuable rocks available for scientific study. Approximately 43,000 meteorites are known on Earth and are egeologicalf samples of extraterrestrial bodies - meteorites are known to originate from asteroids, the Moon, Mars and possibly comets. With expanding exploration of our Solar System, meteorites provide the eground truthf to compare data collected by robotic missions with results gained from a variety of more accurate and precise techniques using laboratories on Earth. This talk will give an introduction to the history of meteorite science and the importance of meteorite collections to the field of meteoritics, planetary and solar system science. Curation of extraterrestrial samples is a particularly pertinent issue, especially with regards to particularly rare samples such as those from Mars like the recent Tissint meteorite. Future sample return missions to asteroids and Mars also pose siginificant challenges around the curation of these precious materials. Issues surrounding the curation of samples and how curation and curatorial actions can influence scientific studies will also be discussed.

  8. Gas flow and fluidization in a thick dynamic regolith: A new mechanism for the formation of chondritic meteorites

    NASA Technical Reports Server (NTRS)

    Huang, Shaoxiong; Sears, Derek W. G.

    1995-01-01

    We have previously shown that size and density sorting in a regolith which has been 'fluidized' by the passage or gases from the interior or the body can quantitatively explain metal-silicate fractionation, an important property of ordinary chondrites. Here we discuss whether the flow rates and flux or volatiles expected from a primitive parent body are likely to be sufficient for this mechanism. Many meteorite parent bodies may have contained volatiles. From a consideration of heat diffusion and fluid mechanics, we calculate the gas flow rate of volatiles (e.g., water) in the regolith of an asteroid-sized object heated by Al-26. Our calculations show that the flow velocities and flux of water vapor are sufficient to produce conditions suitable for fluidization. Other heat sources have yet to be considered, but literature work suggests that they may be equally effective.

  9. Ca-carbonate in the Orgueil (CI) carbonaceous chondrite: Mineralogy, microstructure and implications for parent body history

    NASA Astrophysics Data System (ADS)

    Lee, Martin R.; Nicholson, Kirsty

    2009-04-01

    The Orgueil CI carbonaceous chondrite is a breccia and some of its constituent clasts contain Ca-carbonate grains whose mineralogy is undetermined, but may yield new information on the history of its asteroidal or cometary parent body. Characterisation of one such clast shows that in addition to Ca-carbonate it contains magnetite, olivine and orthopyroxene grains that are supported within a finely crystalline saponite-serpentine-ferrihydrite groundmass. The Ca-carbonate grains are typically rounded, less than 10 μm in diameter, and backscatter Kikuchi patterns identify all those analysed as calcite. Electron backscatter diffraction orientation contrast maps show that most calcites have sub-μm sized e-twins, some of which are cut by corroded grain margins. These microstructures demonstrate that the clast experienced very mild shock during aqueous alteration and probably accompanying impact 'gardening' of the parent body regolith. The sample studied hosts several other millimeter sized clasts and a fine grained clastic matrix that are free of Ca-carbonate, olivine and orthopyroxene although can contain apatite, dolomite and pyrrhotite. Within one of these clasts is a network of phyllosilicate-magnetite veins that are inferred to have acted as fluid flow conduits during parent body aqueous alteration. Sulphur-rich reaction rims within the same clast are likely to have formed during post-fall remobilization and crystallization of pre-terrestrial sulphates. This study provides good evidence for alteration of the CI carbonaceous chondrites in a dynamic parent body regolith.

  10. Phosphate Minerals in Type 4-6 LL Chondrites: The Nature of Fluids on the LL Chondrite Parent Body

    NASA Astrophysics Data System (ADS)

    Jones, R. H.; McCubbin, F. M.; Dreeland, L.; Guan, Y.

    2011-03-01

    Apatite in the LL chondrites is Cl-rich and extremely dry, with H2O contents <100 ppm. We suggest that this apatite may have a significant oxyapatite component. We infer that very dry, halogen-rich fluids pervaded the LL chondrite parent body.

  11. Differences between Antarctic and non-Antarctic meteorites: An assessment

    SciTech Connect

    Koeberl, C. ); Cassidy, W.A. )

    1991-01-01

    The discovery of a statistically significant number of meteorites in Antarctica over the past 20 years has posed many questions. One of the most intriguing suggestions that came up during the study of the Antarctic samples was that there might be a difference between the parent populations of Antarctic and non-Antarctic samples was that there might be a difference between the parent populations of Antarctic and non-Antarctic meteorites. This interpretation was put forward after the detection of a significant difference in the abundances of volatile and mobile trace elements in H, L, and C chondrites and achondrites. Other major differences include the occurrence of previously rare or unknown meteorites, different meteorite-type frequencies, petrographic characteristics, oxygen isotopic compositions, and smaller average masses. Not all differences between the Antarctic and non-Antarctic meteorite populations can be explained by weathering, pairing, or different collection procedures. Variable trace element abundances and distinct differences in the thermal history and thermoluminescence characteristics have to be interpreted as being pre-terrestrial in origin. Such differences imply the existence of meteoroid streams, whose existence poses problems in the framework of our current knowledge of celestial mechanics. In this paper we summarize the contributions in this series and provide a review of the current state of the question for the reality and cause of differences between Antarctic and non-Antarctic meteorites.

  12. Evidence for the existence of Pd-107 in the early solar system. [from Santa Clara iron meteorite data

    NASA Technical Reports Server (NTRS)

    Kelly, W. R.; Wasserburg, G. J.

    1978-01-01

    Measurements of the concentration and isotopic composition of Ag and Pd in the Santa Clara iron meteorite suggest that in situ decay of Pd-107 occurred in the meteorite or its parent body. The initial solar ratio of Pd-107/Pd-110 is estimated from the observed ratio of excess Ag-107/Pd-110, and the value of the Pd ratio is incompatible with an interval of approximately 100,000,000 years between the end of nucleosynthesis and the formation of planetary objects but is compatible with a later injection of material. The inferred existence of Pd-107 and Al-26 indicates that the late injection included freshly synthesized material of both intermediate and low atomic weight on a similar time scale. The significance of the Pd-107/Ag-107 chronometer is considered.

  13. Thermoluminescence and Antarctic meteorites

    NASA Technical Reports Server (NTRS)

    Sears, D. W. G.; Hasan, F. A.

    1986-01-01

    The level of natural thermoluminescence (TL) in meteorites is the result of competition between build-up, due to exposure to cosmic radiation, and thermal decay. Antarctic meteorites tend to have lower natural TL than non-Antarctic meteorites because of their generally larger terrestrial ages. However, since a few observed falls have low TL due to a recent heating event, such as passage within approximately 0.7 astronomical units of the Sun, this could also be the case for some Antarctic meteorites. Dose rate variations due to shielding, heating during atmospheric passage, and anomalous fading also cause natural TL variations, but the effects are either relatively small, occur infrequently, or can be experimentally circumvented. The TL sensitivity of meteorites reflects the abundance and nature of the feldspar. Thus intense shock, which destroys feldspar, causes the TL sensitivity to decrease by 1 to 2 orders of magnitude, while metamorphism, which generates feldspar through the devitrification of glass, causes TL sensitivity to increase by a factor of approximately 10000. The TL-metamorphism relationship is particularly strong for the lowest levels of metamorphism. The order-disorder transformation in feldspar also affect the TL emission characteristics and thus TL provides a means of paleothermometry.

  14. Meteorite fusion crust variability.

    NASA Astrophysics Data System (ADS)

    Thaisen, Kevin G.; Taylor, Lawrence A.

    2009-06-01

    Two assumptions commonly employed in meteorite interpretation are that fusion crust compositions represent the bulk-rock chemistry of the interior meteorite and that the vesicles within the fusion crust result from the release of implanted solar wind volatiles. Electron microprobe analyses of thin sections from lunar meteorite Miller Range (MIL) 05035 and eucrite Bates Nunataks (BTN) 00300 were performed to determine if the chemical compositions of the fusion crust varied and/or represented the published bulk rock composition. It was determined that fusion crust compositions are significantly influenced by the incorporation of fragments from the substrate, and by the composition and grain size of those minerals. Because of compositional heterogeneities throughout the meteorite, one cannot assume that fusion crust composition represents the bulk rock composition. If the compositional variability within the fusion crust and mineralogical differences among thin sections goes unnoticed, then the perceived composition and petrogenetic models of formation will be incorrect. The formation of vesicles within these fusion crusts were also compared to current theories attributing vesicles to a solar wind origin. Previous work from the STONE-5 experiment, where terrestrial rocks were exposed on the exterior of a spacecraft heatshield, produced a vesicular fusion crust without prolonged exposure to solar wind suggesting that the high temperatures experienced by a meteorite during passage through the Earth's atmosphere are sufficient to cause boiling of the melt. Therefore, the assumption that all vesicles found within a fusion crust are due to the release of implanted volatiles of solar wind may not be justified.

  15. Heterogeneous distribution of paramagnetic radicals in insoluble organic matter from the Orgueil and Murchison meteorites

    NASA Astrophysics Data System (ADS)

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

    2002-12-01

    An electron paramagnetic resonance (EPR) investigation was performed on the insoluble organic matter from the Orgueil and Murchison meteorites and on terrestrial coals with similar elemental composition. A complementary electron nuclear double resonance (ENDOR) study was also carried out. The measured g-factors of the observed paramagnetic radicals in the meteoritic organic matter exhibit a similar correlation with the chemical composition as for the type III (i.e., hydrogen-poor) terrestrial coals. The main result, obtained from EPR saturation and 1H ENDOR enhancement measurements, showed that the effective local concentration in radicals of about 3 to 4 × 10 19 spin.g -1 in the meteoritic organic matter is much higher than the average concentration, hence the occurrence of radical-rich regions accounting for 5% and 20% of the total volume for Murchison and Orgueil, respectively. This heterogeneity of concentration seems to be unique among natural organic macromolecules. It is proposed that these radical-rich regions correspond to pristine parts of the organic matter synthesized in conditions close to those prevailing in the interstellar medium, and which have survived the hydrothermal process on the parent body.

  16. Coordinated Chemical and Isotopic Imaging of Bells (CM2) Meteorite Matrix

    NASA Technical Reports Server (NTRS)

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

    2014-01-01

    Meteoritic organic matter is a complex conglomeration of species formed in distinct environments and processes in circumstellar space, the interstellar medium, the Solar Nebula and asteroids. Consequently meteorites constitute a unique record of primordial organic chemical evolution. While bulk chemical analysis has provided a detailed description of the range and diversity of organic species present in carbonaceous chondrites, there is little information as to how these species are spatially distributed and their relationship to the host mineral matrix. 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) aqueous alteration that may have led to aqueous geochromatographic separation of organics and synthesis of new organics coupled to aqueous mineral alteration. Here we present the results of the first coordinated in situ isotopic and chemical mapping study of the Bells meteorite using a newly developed two-step laser mass spectrometer (mu-L(sup 2)MS) capable of measuring a broad range of organic compounds.

  17. SNC meteorites - Clues to Martian petrologic evolution?. [Shergottites, Nakhlites and Chassigny

    NASA Technical Reports Server (NTRS)

    Mcsween, H. Y., Jr.

    1985-01-01

    Shergottites, nakhlites and the Chassigny meteorites (SNC group) may have originated on Mars. The shergottites are medium-grained basalts, the nakhlites are pyroxenites and the Chassigny is a dunite. The SNC group is petrologically diverse but differs from all other known achondrites in terms of mineral chemistry, the redox state, the oxygen isotopic composition and the radiometric ages. The SNC stones are mafic and ultramafic cumulate rocks with mineralogies that indicate rapid cooling and crystallization from tholeiitic magmas which contained water and experienced a high degree of oxidation. The characteristics suggest formation from a large parent body, i.e., a planet, but not earth. The estimated ages for the rocks match the estimated ages for several mapped Martian volcanoes in the Tharsis region. Additionally, the elemental and isotopic abundances of atmospheric gases embedded in melts in the SNC stones match Viking Lander data for the Martian atmosphere. However, reasons are cited for discounting the possibility that a large meteorite(s) collided with Mars about 180 myr ago and served as the mechanism for ejecting the SNC stones to earth.

  18. Carbon isotope composition of individual amino acids in the Murchison meteorite

    SciTech Connect

    Engel, M.H.; Macko, S.A.; Silter, J.A.

    1996-07-01

    A SIGNIFICANT parties of prebiotic organic matter on the early Earth may have been introduced by carbonaceous asteroids and comets.{sup 1} The distribution and stable-isotope composition of individual organic compounds in carbonaceous meteorites, which are thought to be derived from asteroidal parent bodies, may therefore provide important information concerning mechanistic pathways for prebiotic synthesis{sup 2} and the composition of organic matter on Earth before living systems developed.{sup 3} Previous studies{sup 11,12} have shown that meteorite amino acids are enriched in {sup 13}C relatives to their terrestrial counterparts, but individual species were not distinguished. Here we report the {sup 13}C contents of individual amino acids in the Murchison meteorite. The amino acids are enriched in {sup 13}C, indicating an extraterrestrial origin. Alanine is not racemic, and the {sup 13}C enrichment of its D- and L-enantiomers implies that the excess of the L-enantiomer is indigenous rather than terrestrial contamination, suggesting that optically active materials were present in the early Solar System before life began. {copyright} {ital 1996 American Institute of Physics.}

  19. The Meteoritical Bulletin, No. 101

    NASA Astrophysics Data System (ADS)

    Ruzicka, Alex; Grossman, Jeffrey; Bouvier, Audrey; Herd, Christopher D. K.; Agee, Carl B.

    2015-09-01

    Meteoritical Bulletin 101 contains 2639 meteorites accepted by the Nomenclature Committee in 2012, including 1 fall (Battle Mountain), with 2308 ordinary chondrites, 156 carbonaceous chondrites, 63 HED achondrites, 17 relict meteorites, 16 Rumuruti chondrites, 15 enstatite chondrites, 15 ureilites, 10 iron meteorites, 9 lunar meteorites, 9 primitive achondrites, 8 ungrouped achondrites, 7 mesosiderites, 4 Martian meteorites, and 2 Pallasites, and with 1812 from Antarctica, 437 from Asia, 301 from Africa, 43 from South America, 21 from Europe (including Russia), 21 from North America, 3 from Oceania, and 1 from unknown. Information about approved meteorites can be obtained from the Meteoritical Bulletin Database (MBD) available on line at http://www.lpi.usra.edu/meteor/.

  20. Antarctic Meteorite Newsletter. Volume 20

    NASA Technical Reports Server (NTRS)

    Lindstrom, Marilyn M.; Satterwhite, Cecilia E.

    1997-01-01

    The availability of 116 new meteorites from the 1994-1996 collections is announced. There are 4 special chondrites, 2 carbonaceous chondrites, and 1 achondrite among the new meteorites. Also included is a redescription of Lodranite GRA95209.

  1. Three basaltic earth-approaching asteroids and the source of the basaltic meteorites

    SciTech Connect

    Cruikshank, D.P.; Tholen, D.J.; Bell, J.F.; Hartmann, W.K.; Brown, R.H. Hawaii Univ., Honolulu Planetary Science Institute, Tucson, AZ JPL, Pasadena, CA )

    1991-01-01

    Diameters of 1.2, 1.0, and 3.4 km are respectively derived for the earth-approaching asteroids 1983 RD, 1980 PA, and 1985 DO2, whose spectra are virtually identical to that of the basaltic-surfaced large asteroid, Vesta. While probably not fragments of Vesta, the three asteroids may be fragments of one or more Vesta-like parent bodies; it is suggested that they may be fragments of the source body or bodies of the HED meteorites. While these asteroids regoliths have significant insulating properties, they differ from that of the moon in that lunar-like glasses and agglutinates are largely absent. It is noted that asteroids of this kind may have impacted the earth without leaving the chemical signatures associated with the K-T boundary event. 59 refs.

  2. Possible Evidence for Two Subsequent Collisions on a Differentiated Parent Body, (135) Hertha

    NASA Astrophysics Data System (ADS)

    Dykhuis, Melissa J.

    2014-11-01

    The Nysa-Polana complex is a group of low-inclination asteroid families in the inner main belt, bounded in semimajor axis by the ν6 secular resonance and the Jupiter 3:1 mean motion resonance. This group is important as the most likely source region for the target of the OSIRIS-REx mission, (101955) Bennu; however, family membership in the region is complicated by the presence of several dynamically overlapping families with a range of surface reflectance properties. The large, S-type structure in the region (centered at proper elements a = 2.4 AU, e = 0.18, sin(i) = 0.042) appears to be associated with parent body (135) Hertha. This family displays an a-e correlation with a slope of -0.57, consistent with the ejection field of a collision with v_ej = 250 m/s and true anomaly in the range of 150 to 210 deg. This characterization of the ejection field places constraints on the semimajor axis dispersion of the original collision, which permits measurement of the dispersion due to the Yarkovsky effect, improving estimates of the family’s age. Preliminary estimates yield an age of 240 +/- 60 My; this roughly matches age measurements for the P/T extinction event on Earth (252 My).Another, smaller structure overlaps the large Hertha family in proper orbital element space, and also appears to be associated with (135) Hertha. This structure differs from the larger one in SDSS a* color, with reflectance properties more consistent with the X-type (135) Hertha than the surrounding S-type family. These objects form a distinct Yarkovsky "V" signature in a-H space, consistent with a recent collision with significantly less semimajor axis dispersion than the large family. These results have implications for the origin of this structure (second collision on (135) Hertha, core of the original large Hertha family, or unrelated neighboring collision), and the degree of differentiation of the parent body.The Nysa-Polana complex also contains two additional families associated with

  3. Parents' education and child body weight in France: The trajectory of the gradient in the early years.

    PubMed

    Apouey, Bénédicte H; Geoffard, Pierre-Yves

    2016-03-01

    This paper explores the relationship between parental education and offspring body weight in France. Using two large datasets spanning the 1991-2010 period, we examine the existence of inequalities in maternal and paternal education and reported child body weight measures, as well as their evolution across childhood. Our empirical specification is flexible and allows this evolution to be non-monotonic. Significant inequalities are observed for both parents' education--maternal (respectively paternal) high education is associated with a 7.20 (resp. 7.10) percentage points decrease in the probability that the child is reported to be overweight or obese, on average for children of all ages. The gradient with respect to parents' education follows an inverted U-shape across childhood, meaning that the association between parental education and child body weight widens from birth to age 8, and narrows afterward. Specifically, maternal high education is correlated with a 5.30 percentage points decrease in the probability that the child is reported to be overweight or obese at age 2, but a 9.62 percentage points decrease at age 8, and a 1.25 percentage point decrease at age 17. The figures for paternal high education are respectively 5.87, 9.11, and 4.52. This pattern seems robust, since it is found in the two datasets, when alternative variables for parental education and reported child body weight are employed, and when controls for potential confounding factors are included. The findings for the trajectory of the income gradient corroborate those of the education gradient. The results may be explained by an equalization in actual body weight across socioeconomic groups during youth, or by changes in reporting styles of height and weight.

  4. The relict magnetism of meteorites

    NASA Technical Reports Server (NTRS)

    Cisowski, S. M.; Hood, L. L.

    1991-01-01

    Meteorite paleomagnetic studies are reviewed and evaluated. Possible mechanisms for producing early solar system magnetic fields that could have been responsible for the magnetization of some or all meteorite classes are explored. A detailed review of paleointensity results derived from the various classes of meteorites is given, and the likelihood that the results might related to solar or nebulawide magnetic fields is considered. The implications of meteorite magnetism for early solar system evolution are discussed.

  5. Primordial material in meteorites

    NASA Technical Reports Server (NTRS)

    Kerridge, J. F.

    1986-01-01

    Primordial is a term which applied to material that entered the solar system early and became incorporated into a meteorite without totally losing its identity. Identification of such material surviving in meteorites is so far solely through recognition of anomalous isotopic compositions of generally macroscopic entities contained within those meteorites. Isotopic anomalies are, by definition, isotopic compositions which differ from the canonical solar system abundances in ways which cannot be explained in terms of local processes such as mass dependent fractionation, cosmic ray induced spallation or decay of radionuclides. A comprehensive account of isotopic anomalies is impractical here, so it is necessary to be selective. Issues which are potentially addressable through the study of such primordial material are examined. Those issues will be illustrated with specific, but not exhaustive, examples.

  6. Self-Esteem and Body Dissatisfaction in Young Children: Associations with Weight and Perceived Parenting Style

    ERIC Educational Resources Information Center

    Taylor, Amanda; Wilson, Carlene; Slater, Amy; Mohr, Philip

    2012-01-01

    Background: Parenting style has been associated with weight-related outcomes in children, but relationships between parenting, weight, and overweight-related psychological outcomes remain largely unstudied. The aim of the present study was to determine whether parenting was a moderator of the relationship between overweight and psychological…

  7. Amino Acid Chemistry as a Link Between Small Solar System Bodies and Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Glavin, Daniel P.; Ehrenfreund, Pascale; Botta, Oliver; Cooper, George; Bada, Jeffrey L.

    2000-01-01

    Establishing chemical links between meteorites and small solar system bodies, such as comets and asteroids, provides a tool for investigating the processes that occurred during the formation of the solar system. Carbonaceous meteorites are of particular interest, since they may have seeded the early Earth with a variety of prebiotic organic compounds including amino acids, purines and pyrimidines, which are thought to be necessary for the origin of life. Here we report the results of high-performance liquid chromatography (HPLC) based amino acid analyses of the acid-hydrolyzed hot water extracts from pristine interior pieces of the CI carbonaceous chondrites Orgueil and Ivuna and the CM meteorites Murchison and Murray. We found that the CI meteorites Orgueil and Ivuna contained high abundances of beta-alanine and glycine, while only traces of other amino acids like alanine, alpha-amino-n-butryic acid (ABA) and alpha-aminoisobutyric acid (AIB) were detected in these meteorites. Carbon isotopic measurements of beta-alanine and glycine in Orgueil by gas chromatography combustion-isotope ratio mass spectrometry clearly indicate an extraterrestrial origin of these amino acids. The amino acid composition of Orgueil and Ivuna was strikingly different from the CM chondrites Murchison and Murray. The most notable difference was the high relative abundance of B-alanine in Orgueil and Ivuna compared to Murchison and Murray. Furthermore, AIB, which is one of the most abundant amino acids found in Murchison and Murray, was present in only trace amounts in Orgueil and Ivuna. Our amino acid data strongly suggest that the CI meteorites Orgueil and Ivuna came from a different type of parent body than the CM meteorites Murchison and Murray, possibly from an extinct comet. It is generally thought that carbonaceous meteorites are fragments of larger asteroidal bodies delivered via near Earth objects (NEO). Orbital and dynamic studies suggest that both fragments of main belt asteroids

  8. Impact delivery of organic matter on the acapulcoite-lodranite parent-body deduced from C, N isotopes and nanostructures of carbon phases in Acapulco and Lodran

    NASA Astrophysics Data System (ADS)

    Charon, E.; Aléon, J.; Rouzaud, J.-N.

    2014-10-01

    The structure and nanostructures of carbon phases from the Acapulco and Lodran meteorites and their carbon and nitrogen isotopic composition were investigated at the nanometer and micrometer scale using a systematic combination of Raman microspectrometry, high-resolution transmission electron microscopy and secondary ion mass spectrometry to determine their origin and thermal evolution. Several morphological types were recognized belonging to roughly two isotopic and structural families: coarse carbon grains and rosettes, only found in Acapulco, and vein-like carbon occurrences present in both Acapulco and Lodran. Carbon phases in Acapulco are highly graphitized, and show a genetic relationship with metal indicative of metal-assisted graphitization. By contrast, carbon phases in Lodran are exclusively disordered mesoporous turbostratic carbons, in spite of their inclusion in metal and the higher peak temperature experienced by the Lodran parent body. δ13C values range between -59‰ and +37‰ in Acapulco and between -38‰ and -1‰ in Lodran and show in both cases a peak in their distribution at the value of chondritic insoluble organic matter (IOM, -10‰ to -15‰). N concentrations together with δ15N values indicate a mixing between a component akin to chondritic IOM in Lodran with a δ15N value around +10‰ to +20‰ and a component akin to that in the most N-poor Acapulco graphites. The latter are systematically depleted in 15N with a δ15N value constant at ∼-140‰ for N concentrations below ∼1.4 wt%. These observations can be explained if carbon phases in Acapulco and Lodran result from the late impact introduction of CI-CM like IOM, after significant cooling of the parent-body, and subsequent carbonization and graphitization of IOM by interaction with FeNi metal by the heat wave induced by the impact. Temperatures probably reached 900 °C in Acapulco, enough to achieve metal-assisted graphitization but were not significantly higher than 650 °C in

  9. Samarium-neodymium evolution of meteorites

    NASA Technical Reports Server (NTRS)

    Prinzhofer, A.; Papanastassiou, D. A.; Wasserburg, G. J.

    1992-01-01

    The feasibility of using Sm-147 and Sm-146 as chronometers was investigated using Sm-Nd data obtained on three meteorites: Ibitira, Morristown, and Acapulco. The results of isotope analyses demonstrate the presence of in situ decay of short-lived Sm-146 in these meteorites with initial abundances of Sm-146/Sm-144 between 0.009 and 0.007 in different meteorites. Precisely defined Sm-147/Nd-143 internal isochrons were obtained yielding ages equal to 4.46 +/-0.02 AE for Ibitira, 4.47 +/-0.02 AE for Morristown, and 4.60 +/-0.03 AE for Acapulco. However, detailed examination of the coupled Sm-147/Nd-143 and Sm-146/Nd-142 parent-daughter systematics and of initial Nd-143/Nd-144 values indicated the presence of inconsistencies in the data in spite of the precise isochrons, indicating the need for care in the interpretation of the parent-daughter systematics, even when they appear well behaved.

  10. Iron Meteorite on Mars

    NASA Technical Reports Server (NTRS)

    2005-01-01

    NASA's Mars Exploration Rover Opportunity has found an iron meteorite on Mars, the first meteorite of any type ever identified on another planet. The pitted, basketball-size object is mostly made of iron and nickel. Readings from spectrometers on the rover determined that composition. Opportunity used its panoramic camera to take the images used in this approximately true-color composite on the rover's 339th martian day, or sol (Jan. 6, 2005). This composite combines images taken through the panoramic camera's 600-nanometer (red), 530-nanometer (green), and 480-nanometer (blue) filters.

  11. The Chelyabinsk Fireball and Meteorite.

    NASA Astrophysics Data System (ADS)

    Galimov, E. M.; Kolotov, V. P.; Nazarov, M. A.; Kostitsyn, Yu. A.; Kubrakova, I. V.; Kononkova, N. N.; Alekseev, I. A.; Koshkarov, L. L.; Badyukov, D. D.; Sevastyanov, V. S.; Pillinger, C. T.; Greenwood, R. C.; Verchovsky, A. B.; Johnson, D.; Tindle, A. G.; Buikin, A.

    2013-09-01

    On 15th February 2013 an extraordinarily large fireball detonated in the atmosphere over Chelyabinsk, Russia, with a total energy equivalent to 440 kilotons of TNT. It was the most energetic natural atmospheric occurrence since the Tunguska incident in 1908 and caused many injuries and extensive property damage. Geochemical and isotopic data show that the meteorite samples recovered after the event are LL5 type ordinary chondrites with a S4 shock history. The many thousands of small fragments comprise either of two distinct lithologies: a hondrule-rich light coloured material (~66%) or a less-abundant (~34%) dark shock-melt rather than mixtures. The break-up of the object, i.e. the explosion, appears to have been dictated by the object's pre-entry two component structure, which probably formed during a major collision in the asteroid belt 290 My ago. The Chelyabinsk event demonstrates that effective asteroid-hazard mitigation requires structural knowledge of threatening body similar to that obtained by the Hayabusa spacecraft at asteroid Itokawa. The observations made for Chelyabinsk suggest that the Tunguska bolide may also have been a structurally weakened object. Studies of the samples are still at an early stage. A full petrological description of the meteorite lithologies, geochemical and isotopic analyses, chronological data and fission track information will be available by the time of the conference

  12. Records of the Moon-forming impact and the 470 Ma disruption of the L chondrite parent body in the asteroid belt from U-Pb apatite ages of Novato (L6)

    NASA Astrophysics Data System (ADS)

    Yin, Qing-Zhu; Zhou, Qin; Li, Qiu-Li; Li, Xian-Hua; Liu, Yu; Tang, Guo-Qiang; Krot, Alexander N.; Jenniskens, Peter

    2014-08-01

    Novato, a newly observed fall in the San Francisco Bay area, is a shocked and brecciated L6 ordinary chondrite containing dark and light lithologies. We have investigated the U-Pb isotope systematics of coarse Cl-apatite grains of metamorphic origin in Novato with a large geometry ion microprobe. The U-Pb systematics of Novato apatite reveals an upper intercept age of 4472 ± 31 Ma and lower intercept age of 473 ± 38 Ma. The upper intercept age is within error identical to the U-Pb apatite age of 4452 ± 21 Ma measured in the Chelyabinsk LL5 chondrite. This age is interpreted to reflect a massive collisional resetting event due to a large impact associated with the peak arrival time at the primordial asteroid belt of ejecta debris from the Moon-forming giant impact on Earth. The lower intercept age is consistent with the most precisely dated Ar-Ar ages of 470 ± 6 Ma of shocked L chondrites, and the fossil meteorites and extraterrestrial chromite relicts found in Ordovician limestones with an age of 467.3 ± 1.6 Ma in Sweden and China. The lower intercept age reflects a major disturbance related to the catastrophic disruption of the L chondrite parent body most likely associated with the Gefion asteroid family, which produced an initially intense meteorite bombardment of the Earth in Ordovician period and reset and degassed at least approximately 35% of the L chondrite falls today. We predict that the 470 Ma impact event is likely to be found on the Moon and Mars, if not Mercury.

  13. Siderophile Element Depletion in the Angrite Parent Body (APB) Mantle: Due to Core Formation?

    NASA Technical Reports Server (NTRS)

    Righter, K.

    2008-01-01

    The origin of angrites has evaded scientists due in part to unusual mineralogy, oxidized character, and small numbers of samples. Increased interest in the origin of angrites has stemmed from the recovery of approximately 10 new angrites in the past decade. These new samples have allowed meteoriticists to recognize that angrites are compositionally diverse, old, and record very early differentiation. Also, a magma ocean has been proposed to have been involved in APB early differentiation, but this remains untested for siderophile elements which are commonly cited as one of the main lines of evidence for magma oceans on the early Earth, Moon, Mars and eucrite parent body (e.g., [6]). And recent suggestions that angrites may or may not be from Mercury have also peaked interest in these achondrites. Given all of this background, a detailed understanding of the early differentiation process is desired. Previous efforts at examining siderophile element (SE) concentrations with respect to core formation processes in the APB have not resulted in any definite conclusions regarding segregation of a metallic core. The goal of this study is to summarize what is known about SE concentrations in the suite, estimate depletions of SE compared to chondrites, and apply metal/silicate experimental partition coefficients to assess whether the APB had a core.

  14. The Meteoritic Component in Impact Deposits

    NASA Technical Reports Server (NTRS)

    Kyte, Frank T.

    2003-01-01

    marine sediments that was attributed to an increase in interplanetary dust due to a shower of comets invading the inner solar system. We planned to detect a change in the Cr-isotopic composition in the flux of fine-grained extraterrestrial matter to ocean sediments. This would provide evidence for the comet shower hypothesis. We planned attempt to locate late Eocene impact deposits in a new high resolution, hi-latitude site that had the potential for excellent preservation and new information of the sources and effects of these impacts. Although most impacts on Earth occur in deep-ocean basins, only one such event is known - the late Pliocene impact of the Eltanin asteroid. The ejecta from this impact includes Ir- rich impact melt, spherules, and actual meteorites from the km-sized mesosiderite asteroid. Through a study of the ejecta, we can learn about the formation, distribution, alteration and preservation of Ir-rich deposits. We can also learn about meteorite survival during hypervelocity impacts and we can study pieces of a km-sized object to learn more about the mesosiderite parent body. Analyses of sediment cores and geophysical exploration of the impact site can further our understanding of the processes involved in deep-ocean impacts and potential effects on the terrestrial climate and biosphere. We planned analyses of this ejecta, a search for ejecta 5000 km distant from the impact area, and a new oceanographic expedition to study and sample the impact site. In addition to these three specific areas of research, the PI planned to remain flexible and available to exploit new opportunities presented by new discoveries, and to engage in new collaborations if other researchers require his expertise to develop new projects that fit within the objectives of the overall research program.

  15. The composition of the mantle of the eucrite parent body and the origin of eucrites

    NASA Technical Reports Server (NTRS)

    Jones, J. H.

    1984-01-01

    Previous estimates of the composition of the EPB have tacitly assumed chondritic abundances of refractory LIL elements. A model is presented here which utilizes refractory element ratios instead. Consideration of these ratios and of known olivine-liquid partition coefficients for Sc, Mg and Si imply that the EPB mantle may be accurately modeled as a simple mixture of 25 percent eucrite + 75 percent olivine. The model also implies that eucrites such as Juvinas and Sioux County were derived by large degrees of partial melting (20-30 percent). Comparison of the model EPB mantle to known meteorite classes indicates a similarity between the element abundances of the EPB and C3 chondrites.

  16. Fluid flow in chondritic parent bodies: deciphering the compositions of planetesimals

    PubMed

    Young; Ash; England; Rumble

    1999-11-12

    Alteration of the Allende meteorite caused shifts in oxygen isotope ratios along a single mass fractionation line. If alteration was caused by aqueous fluid, the pattern of oxygen isotope fractionation can be explained only by flow of reactive water down a temperature gradient. Down-temperature flow of aqueous fluid within planetesimals is sufficient to explain the mineralogical and oxygen isotopic diversity among CV, CM, and CI carbonaceous chondrites and displacement of the terrestrial planets from the primordial slope 1. 00 line on the oxygen three-isotope plot.

  17. Chalcophile Elements in Martian Meteorites Indicate a Low Sulfur Content in the Martian Interior

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Becker, H.

    2016-08-01

    Fractionation of chalcophile elements shows that the parent magmas of SNC meteorites formed and evolved at sulfide undersaturated conditions. The Mars has low sulfur contents in the mantle and the core.

  18. The 10Be contents of SNC meteorites

    NASA Technical Reports Server (NTRS)

    Pal, D. K.; Tuniz, C.; Moniot, R. K.; Savin, W.; Vajda, S.; Kruse, T.; Herzog, G. F.

    1986-01-01

    Several authors have explored the possibility that the Shergottites, Nakhlites, and Chassigny (SNC) came from Mars. The spallogenic gas contents of the SNC meteorites have been used to: constrain the sizes of the SNC's during the last few million years; to establish groupings independent of the geochemical ones; and to estimate the likelihood of certain entries in the catalog of all conceivable passages from Mars to Earth. The particular shielding dependence of Be-10 makes the isotope a good probe of the irradiation conditions experienced by the SNC meteorites. The Be-10 contents of nine members of the group were measured using the technique of accelerator mass spectrometry. The Be-10 contents of Nakhla, Governador Valadares, Chassigny, and probably Lafayette, about 20 dpm/kg, exceed the values expected from irradiation of the surface of a large body. The Be-10 data therfore do not support scenario III of Bogard et al., one in which most of the Be-10 in the SNC meteorites would have formed on the Martian surface; they resemble rather the Be-10 contents found in many ordinary chondrites subjected to 4 Pi exposures. The uncertainties of the Be-10 contents lead to appreciable errors in the Be-10 ages, t(1) = -1/lambda ln(1 Be-10/Be-10). Nonetheless, the Be-10 ages are consistent with the Ne-21 ages calculated assuming conventional, small-body production rates and short terrestrial ages for the finds. It is believed that this concordance strengthens the case for at least 3 different irradiation ages for the SNC meteorites. Given the similar half-thicknesses of the Be-10 and Ne-21 production rates, the ratios of the Be-10 and Ne-21 contents do not appear consistent with common ages for any of the groups. In view of the general agreement between the Be-10 and Ne-21 ages it does not seem useful at this time to construct multiple-stage irradiation histories for the SNC meteorites.

  19. Timescales and settings for alteration of chondritic meteorites

    SciTech Connect

    Krot, A N; Hutcheon, I D; Brearley, A J; Pravdivtseva, O V; Petaev, M I; Hohenberg, C M

    2005-11-16

    Most groups of chondritic meteorites experienced diverse styles of secondary alteration to various degrees that resulted in formation of hydrous and anhydrous minerals (e.g., phyllosilicates, magnetite, carbonates, ferrous olivine, hedenbergite, wollastonite, grossular, andradite, nepheline, sodalite, Fe,Ni-carbides, pentlandite, pyrrhotite, Ni-rich metal). Mineralogical, petrographic, and isotopic observations suggest that the alteration occurred in the presence of aqueous solutions under variable conditions (temperature, water/rock ratio, redox conditions, and fluid compositions) in an asteroidal setting, and, in many cases, was multistage. Although some alteration predated agglomeration of the final chondrite asteroidal bodies (i.e. was pre-accretionary), it seems highly unlikely that the alteration occurred in the solar nebula, nor in planetesimals of earlier generations. Short-lived isotope chronologies ({sup 26}Al-{sup 26}Mg, {sup 53}Mn-{sup 53}Cr, {sup 129}I-{sup 129}Xe) of the secondary minerals indicate that the alteration started within 1-2 Ma after formation of the Ca,Al-rich inclusions and lasted up to 15 Ma. These observations suggest that chondrite parent bodies must have accreted within the first 1-2 Ma after collapse of the protosolar molecular cloud and provide strong evidence for an early onset of aqueous activity on these bodies.

  20. Multivariate Statistical Analysis of Volatile Trace Elements in H Chondrites: Implications for Parent Body Structure

    NASA Astrophysics Data System (ADS)

    Wolf, S. F.; Lipschutz, M. E.

    1993-07-01

    The perception among meteoriticists is that contents of the volatile trace elements systematically decrease with shock and particularly petrologic type. This perception affects views that investigators have of the early history and structure of the H chondrite parent body. Measurement of a variety of volatile trace elements in a statistically significant number of samples accompanied by chemometric data analysis techniques developed for interpretation of trace- element data [1] should maximize the amount of genetic information available from the volatile trace elements and offer clues to the early thermal history of the H chondrite parent body. Volatile trace-element data exist for 58 H chondrite falls: the complete dataset includes Co, Rb, Ag, Se, Cs, Te, Zn, Cd, Bi, Tl, and In (listed in increasing order of volatility) [2,3]. This dataset includes 13 H4, 32 H5, and 13 H6 chondrites, which cover the full range of shock facies from a through f. To examine the effect that shock has on volatile trace-element concentrations in H4-6 chondrites, we have compared data for the least-shocked samples (shock facies a-b) with the most shocked samples (shock facies c-f) using both univariate (Student's t-test) and multivariate techniques (linear discriminant analysis). The results demonstrate no reason to doubt the null hypothesis of no difference in volatile trace-element composition between shocked and unshocked H4-6 chondrites at any reasonable significance level. This situation contrasts sharply with the strong difference found between shocked and unshocked L chondrites [4]. The role of shock in establishing volatile trace- element contents in H and L chondrites clearly differs. Univariate comparisons between H4, H5, and H6 chondrites demonstrate that only Cs varies significantly with petrologic type (prob. > F 0.0006) with concentration decreasing monotonically with increasing petrographic type. Box- and-whisker plots of volatile trace-element contents reveal a general

  1. Microfossils in Carbonaceous Meteorites

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.

    2009-01-01

    Microfossils of large filamentous trichomic prokaryotes have been detected during in-situ investigations of carbonaceous meteorites. This research has been carried out using the Field Emission Scanning Electron Microscope (FESEM) to examine freshly fractured interior surfaces of the meteorites. The images obtained reveal that many of these remains are embedded in the meteorite rock matrix. Energy Dispersive X-Ray Spectroscopy (EDS) studies establish that the filamentous microstructures have elemental compositions consistent with the meteorite matrix, but are often encased within carbon-rich electron transparent sheath-like structures infilled with magnesium sulfate. This is consistent with the taphonomic modes of fossilization of cyanobacteria and sulphur bacteria, since the life habits and processes of these microorganisms frequently result in distinctive chemical biosignatures associated with the properties of their cell-walls, trichomes, and the extracellular polymeric substances (EPS) of the sheath. In this paper the evidence for biogenicity presented includes detailed morphological and morphometric data consistent with known characteristics of uniseriate and multiseriate cyanobacteria. Evidence for indigeneity includes the embedded nature of the fossils and elemental compositions inconsistent with modern biocontaminants.

  2. Carbon in primitive meteorites

    NASA Technical Reports Server (NTRS)

    Kerridge, John F.

    1990-01-01

    No meteorites are truly primitive, in the sense of being pristine collections of interstellar grains or solar-nebular condensates. Nonetheless, some chrondritic meteorites have been so little altered by secondary processing that they are commonly termed primitive and it is almost a definition of such chondrites that they contain significant quantities of carbon. Most of that carbon is of apparently local, i.e., solar-system, origin but a proportion that ranges from trace, in some cases, to minor, in others, is believed to be exotic, i.e., of circumstellar or interstellar origin, and it is upon such material that researchers focus here. The nature of the meteoritic samples and the techniques used to analyse them are briefly discussed and the observational record is surveyed. Clearly, the study of exotic carbon preserved in meteorites has been informative about sites of nucleosynthesis, processes of nucleation and growth of grains in stellar outflows, grain survival in the interstellar medium, and many other topics of astrophysical significance. Much more work, particularly of an interdisciplinary nature remains to be done, however.

  3. Microfossils in carbonaceous meteorites

    NASA Astrophysics Data System (ADS)

    Hoover, Richard B.

    2009-08-01

    Microfossils of large filamentous trichomic prokaryotes have been detected during in-situ investigations of carbonaceous meteorites. This research has been carried out using the Field Emission Scanning Electron Microscope (FESEM) to examine freshly fractured interior surfaces of the meteorites. The images obtained reveal that many of these remains are embedded in the meteorite rock matrix. Energy Dispersive X-Ray Spectroscopy (EDS) studies establish that the filamentous microstructures have elemental compositions consistent with the meteorite matrix, but are often encased within carbon-rich electron transparent sheath-like structures infilled with magnesium sulfate. This is consistent with the taphonomic modes of fossilization of cyanobacteria and sulphur bacteria, since the life habits and processes of these microorganisms frequently result in distinctive chemical biosignatures associated with the properties of their cell-walls, trichomes, and the extracellular polymeric substances (EPS) of the sheath. In this paper the evidence for biogenicity presented includes detailed morphological and morphometric data consistent with known characteristics of uniseriate and multiseriate cyanobacteria. Evidence for indigeneity includes the embedded nature of the fossils and elemental compositions inconsistent with modern bio-contaminants.

  4. Antarctic Meteorite Location Map Series

    NASA Technical Reports Server (NTRS)

    Schutt, John (Editor); Fessler, Brian (Editor); Cassidy, William (Editor)

    1989-01-01

    Antarctica has been a prolific source of meteorites since meteorite concentrations were discovered in 1969. The Antarctic Search For Meteorites (ANSMET) project has been active over much of the Trans-Antarctic Mountain Range. The first ANSMET expedition (a joint U.S.-Japanese effort) discovered what turned out to be a significant concentration of meteorites at the Allan Hills in Victoria Land. Later reconnaissance in this region resulted in the discovery of meteorite concentrations on icefields to the west of the Allan Hills, at Reckling Moraine, and Elephant Moraine. Antarctic meteorite location maps (reduced versions) of the Allan Hills main, near western, middle western, and far western icefields and the Elephant Moraine icefield are presented. Other Antarctic meteorite location maps for the specimens found by the ANSMET project are being prepared.

  5. The Meteoritical Bulletin, No. 102

    NASA Astrophysics Data System (ADS)

    Ruzicka, Alex; Grossman, Jeffrey; Bouvier, Audrey; Herd, Christopher D. K.; Agee, Carl B.

    2015-09-01

    Meteoritical Bulletin 102 contains 3141 meteorites including 12 falls (Boumdeid (2003), Boumdeid (2011), Braunschweig, Chelyabinsk, Dongyang, Draveil, Heyetang, Indian Butte, Katol, Ladkee, Ouadangou, Xining), with 2611 ordinary chondrites, 264 HED achondrites, 124 carbonaceous chondrites, 30 ureilites, 20 Martian meteorites, 16 primitive achondrites, 16 Rumuruti chondrites, 15 mesosiderites, 12 iron meteorites, 10 lunar meteorites, 9 enstatite chondrites, 4 enstatite achondrites, 4 Pallasites, 4 ungrouped achondrites, and 2 angrites, and with 1708 from Antarctica, 956 from Africa, 294 from South America, 126 from Asia, 47 from North America, 6 from Europe (including Russia), and 4 from Oceania. Information about approved meteorites can be obtained from the Meteoritical Bulletin Database (MBD) available on line at http://www.lpi.usra.edu/meteor/.

  6. Huge waves of meteorite origin

    NASA Astrophysics Data System (ADS)

    Pelinovsky, Efim; Kozelkov, Andrey; Kurkin, Andrey

    2016-04-01

    Asteroid and meteorite risk is now actively investigated in various aspects. If the meteorite falls in the ocean it can generate huge waves with heights exceeded 10 m. For whole history about 10-20 events related with entry of meteorite in water are known. The last event occurred on February 15, 2013 when the meteorite exploded in sky of Chelyabinsk (Russia) and its big piece entered in the Chebarkul Lake. Very often, huge waves of meteorite origin are computed using the conception of equivalent (parametrical) source, whose parameters are determined through meteorite characteristics. Recently, direct methods based on numerical simulations of the Reynolds-averaged Navier-Stokes equations (RANS) have been applied to study wave processes generated by the entry of meteorite. These approaches and their applications to the historic events are discussed in paper.

  7. Diamond xenolith and matrix organic matter in the Sutter's Mill meteorite measured by C-XANES

    NASA Astrophysics Data System (ADS)

    Kebukawa, Yoko; Zolensky, Michael E.; Kilcoyne, A. L. David; Rahman, Zia; Jenniskens, Peter; Cody, George D.

    2014-11-01

    The Sutter's Mill (SM) meteorite fell in El Dorado County, California, on April 22, 2012. This meteorite is a regolith breccia composed of CM chondrite material and at least one xenolithic phase: oldhamite. The meteorite studied here, SM2 (subsample 5), was one of three meteorites collected before it rained extensively on the debris site, thus preserving the original asteroid regolith mineralogy. Two relatively large (10 μm sized) possible diamond grains were observed in SM2-5 surrounded by fine-grained matrix. In the present work, we analyzed a focused ion beam (FIB) milled thin section that transected a region containing these two potential diamond grains as well as the surrounding fine-grained matrix employing carbon and nitrogen X-ray absorption near-edge structure (C-XANES and N-XANES) spectroscopy using a scanning transmission X-ray microscope (STXM) (Beamline 5.3.2 at the Advanced Light Source, Lawrence Berkeley National Laboratory). The STXM analysis revealed that the matrix of SM2-5 contains C-rich grains, possibly organic nanoglobules. A single carbonate grain was also detected. The C-XANES spectrum of the matrix is similar to that of insoluble organic matter (IOM) found in other CM chondrites. However, no significant nitrogen-bearing functional groups were observed with N-XANES. One of the possible diamond grains contains a Ca-bearing inclusion that is not carbonate. C-XANES features of the diamond-edges suggest that the diamond might have formed by the CVD process, or in a high-temperature and -pressure environment in the interior of a much larger parent body.

  8. Laboratory experiments on the impact disruption of iron meteorites at temperature of near-Earth space

    NASA Astrophysics Data System (ADS)

    Katsura, Takekuni; Nakamura, Akiko M.; Takabe, Ayana; Okamoto, Takaya; Sangen, Kazuyoshi; Hasegawa, Sunao; Liu, Xun; Mashimo, Tsutomu

    2014-10-01

    Iron meteorites and some M-class asteroids are generally understood to be fragments that were originally part of cores of differentiated planetesimals or part of local melt pools on primitive bodies. The parent bodies of iron meteorites may have formed in the terrestrial planet region, from which they were then scattered into the main belt (Bottke, W.F., Nesvorný, D., Grimm, R.E., Morbidelli, A., O'Brien, D.P. [2006]. Nature 439, 821-824). Therefore, a wide range of collisional events at different mass scales, temperatures, and impact velocities would have occurred between the time when the iron was segregated and the impact that eventually exposed the iron meteorites to interplanetary space. In this study, we performed impact disruption experiments of iron meteorite specimens as projectiles or targets at room temperature to increase understanding of the disruption process of iron bodies in near-Earth space. Our iron specimens (as projectiles or targets) were almost all smaller in size than their counterparts (as targets or projectiles, respectively). Experiments of impacts of steel specimens were also conducted for comparison. The fragment mass distribution of the iron material was different from that of rocks. In the iron fragmentation, a higher percentage of the mass was concentrated in larger fragments, probably due to the ductile nature of the material at room temperature. The largest fragment mass fraction f was dependent not only on the energy density but also on the size d of the specimen. We assumed a power-law dependence of the largest fragment mass fraction to initial peak pressure P0 normalized by a dynamic strength, Y, which was defined to be dependent on the size of the iron material. A least squares fit to the data of iron meteorite specimens resulted in the following relationship: f∝∝d, indicating a large size dependence of f. Additionally, the deformation of the iron materials in high-velocity shots was found to be most significant when the