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Sample records for allende carbonaceous chondrite

  1. No nebular magnetization in the Allende CV carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Fu, R. R.; Lima, E. A.; Weiss, B. P.

    2014-10-01

    Magnetic fields in the solar nebula may have played a central role in mass and angular momentum transport in the protosolar disk and facilitated the accretion of the first planetesimals. Thought to be key evidence for this hypothesis is the high unblocking-temperature, randomly oriented magnetization in chondrules in the Allende CV carbonaceous chondrite. However, it has recently been realized that most of the ferromagnetic minerals in Allende are products of secondary processes on the parent planetesimal. Here we reevaluate the pre-accretional magnetism hypothesis for Allende using new paleomagnetic analyses of chondrules including the first measurements of mutually oriented subsamples from within individual chondrules. We confirm that Allende chondrules carry a high-temperature component of magnetization that is randomly oriented among chondrules. However, we find that subsamples of individual chondrules are also non-unidirectionally magnetized. Therefore, the high-temperature magnetization in Allende chondrules is not a record of nebular magnetic fields and is instead best explained by remagnetization during metasomatism in a <8 μT magnetic field. This low field intensity suggests that any core dynamo on the CV parent body decayed before the end of metasomatism, likely <40 My after the formation of calcium aluminum-rich inclusions (CAIs). Despite widespread practice, the magnetization in Allende should not be used to constrain magnetic fields in the protosolar nebula.

  2. Cosmogenic radionuclides in the Allende and Murchison carbonaceous chondrites.

    NASA Technical Reports Server (NTRS)

    Cressy, P. J., Jr.

    1972-01-01

    Measurements were made of Na-22, Al-26, Mn-54, and Co-60 produced by cosmic rays in five samples of the Allende C3 meteorite and in one specimen of Murchison (C2); Sc-46, V-48, Cr-51, and Co-57 were also measured in several of these samples. Comparison of observed Allende Co-60 activities with calculated neutron-capture production rates yields a depth scale for Allende that appears unambiguous to about 30-cm depth. Using this scale, the production of Al-26 is constant to a depth in excess of 30 cm, Na-22 activity increases 30% from near the surface of Allende to 20- to 30-cm depth, and Mn-54 production increases 50% over the same depth range.

  3. Intergrown mica and montmorillonite in the Allende carbonaceous chondrite

    NASA Technical Reports Server (NTRS)

    Tomeoka, K.; Buseck, P. R.

    1982-01-01

    High resolution transmission electron microscopy (HRTEM) observations were made of a mixture of mica and montmorillonite from fine-grained calcium, aluminum inclusions (CAI) in the Allende C3(V) meteorite. A petrographic thin section having a diameter of 4 mm contained CAI fragments ranging from less than 1 to 50 microns. The observed textural and chemical characteristics placed the inclusion in the fine-grained alkali-rich spinel aggregate category of Warks' (1979) classifications of CAIs and as type 3 in Kornacki's classifications of fine grains in Allende. Chemical analyses were performed on the phyllosilicate grains observed in the TEM scan by means of an X ray observed, and the proximity to the matrix boundary suggests a metamorphism which included aqueous alteration at a relatively low temperature.

  4. Rare earth elements in Ca-phosphates of Allende carbonaceous chondrite

    SciTech Connect

    Ebihara, M.; Honda, M.

    1987-09-01

    The Ca-phosphate phases in the Allende CV3 meteorite were selectively dissolved in ammoniacal EDTA solution and measured for abundances of the rare earth elements (REE) by radiochemical neutron activation and mass-spectrometric isotope dilution analyses. The REE abundances in CA-phosphates of Allende are remarkably different from those of ordinary chondrites. All the REE except Eu were observed to be enriched by factors of 50-100 relative to the Cl values. This is 3-4 times lower than concentrations of REE in the ordinary-chondrite phosphates. Allende phosphates have a small positive Eu anomaly, in contrast to the large negative Eu anomaly in phosphates from ordinary chondrites. Though the positive Eu anomaly in Allende Ca-phosphates is puzzling, the lack of a negative Eu anomaly in Allende Ca-phosphates suggests that they never have been in equilibrium with Allende coarse-grained Ca, Al-rich inclusions or their precursor materials. 42 references.

  5. Mercury Abundances and Isotopic Compositions in the Murchison (CM) and Allende (CV)Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Lauretta, D. S.; Klaue, B.; Blum, J. D.; Buseck, P. R.

    2001-01-01

    The abundance and isotopic composition of Hg was determined in bulk samples of both the Murchison (CM) and Allende (CV) carbonaceous chondrites using single- and multi-collector inductively coupled plasma mass spectrometry (ICP-MS). The bulk abundances of Hg are 294 6 15 ng/g in Murchison and 30.0 6 1.5 ng/g in Allende. These values are within the range of previous measurements of bulk Hg abundances by neutron activation analysis (NAA). Prior studies suggested that both meteorites contain isotopically anomalous Hg, with d l 96/202Hg values for the anomalous, thermal-release components from bulk samples ranging from 2260 %o to 1440 9/00 in Murchison and from 2620 9/00 to 1540 9/00 in Allende (Jovanovic and Reed, 1976a; 1976b; Kumar and Goel, 1992). Our multi-collector ICP-MS measurements suggest that the relative abundances of all seven stable Hg isotopes in both meteorites are identical to terrestrial values within 0.2 to 0.5 9/00m. On-line thermal-release experiments were performed by coupling a programmable oven with the singlecollector ICP-MS. Powdered aliquots of each meteorite were linearly heated from room temperature to 900 C over twenty-five minutes under an Ar atmosphere to measure the isotopic composition of Hg released fiom the meteorites as a h c t i o n of temperature. In separate experiments, the release profiles of S and Se were determined simultaneously with Hg to constrain the Hg distribution within the meteorites and to evaluate the possibility of Se interferences in previous NAA studies. The Hg-release patterns differ between Allende and Murchison. The Hg-release profile for Allende contains two distinct peaks, at 225" and 343"C, whereas the profile for Murchison has only one peak, at 344 C. No isotopically anomalous Hg was detected in the thermal-release experiments at a precision level of 5 to 30 9/00, depending on the isotope ratio. In both meteorites the Hg peak at ;340"C correlates with a peak in the S-release profile. This correlation

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  7. Preliminary Results of the Investigation of the Carbonaceous Chondrites Nagoya, Allende, and Murray

    NASA Technical Reports Server (NTRS)

    Rozanov, Alexei Yu.; Hoover, Richard B.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    As part of a long-term study of morphological biomarkers in Astromaterials, we are documenting a variety of features considered to be indigenous to ancient terrestrial rocks and carbonaceous meteorites. In preparation for the study of samples returned from Mars and other bodies of our Solar System, it is imperative that we establish a database of the nature and morphology of known bacterial fossils in Earth rocks and biomorphic microstructures which may represent microfossils in meteorites. The process of fossilization or mineralization can cause major changes in morphologies and textures of the original organisms and the study of fossilized terrestrial organisms can help provide insight into the interpretation of mineral biomarkers and abiotic microstructures which may mimic certain aspects of microfossils. One class of biomarkers consists of biominerals which have either been precipitated directly by microorganisms, or whose precipitation has been influenced by the organisms. Such microbe-mediated mineral formation may include important clues to the size, shape, and environment of the microorganisms. This paper describes the detection of possible microbe-mediated minerals, biomorphic microstructures and possible microfossils in the Nagoya, Allende, and Murray Carbonaceous Chondrites.

  8. Microbial Contamination of Allende and Murchison Carbonaceous Chondrites; Developing a Protocol for Life Detection in Extraterrestrial Materials Using Biotechnology

    NASA Technical Reports Server (NTRS)

    Steele, A.; Whitby, C.; Griffin, C.; Toporski, J. K. W.; Westall, F.; Saunders, J. R.; McKay, D. S.

    2001-01-01

    The arguments used to refute the McKay et al., (1996) hypothesis of possible Martian life in ALH84001 failed to use contamination of the meteorite as a source. This has worrying implications for our ability to detect terrestrial microbiota in meteorites and therefore any potential extraterrestrial biosignatures in both meteorites and possible returned samples. We report on imaging and microbial culturing of both Allende and Murchison carbonaceous chondrites and on the use of molecular biology techniques on a sample of Allende. Contaminating fungi and bacteria were observed (in the case of Murchison) and cultured from both meteorites. DNA was successfully extracted and subsequent PCR showed the presence of both bacterial and fungal DNA although no Archaea were detected. These results show that it is possible to use molecular biological techniques on very small quantities (300 mg) of extraterrestrial material.

  9. An unusual layered mineral in chondrules and aggregates of the Allende carbonaceous chondrite

    NASA Technical Reports Server (NTRS)

    Tomeoka, K.; Buseck, P. R.

    1982-01-01

    Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive X ray (EDS) and electron energy loss (EELS) spectroscopy examinations of the microstructures and phase relationships of minerals in opaque spherules in the Allende chondrules and aggregates are reported. The studies were carried out on petrographic thin sections which were ion-thinned. A significant metasomatic effect was observed in a highly oxidizing condition of a later cooled stage. An unusually layered Fe-, Ni-, and O-rich mineral related to serpentine was found to occur in the opaque specimen, and was judged to occur by alteration of olivine. It is noted that low temperature and a hydrous condition would have been required for the formation of the serpentine in the spherules, the first observed in Allende. It is suggested that the aqueous conditions occurred before the final stage of the meteorite formation, and proceeded in a nonterrestrial manner.

  10. Fluorescent organic matter in carbonaceous chondrites.

    PubMed

    Murae, T

    1999-01-01

    Fluorescent organic matter in carbonaceous chondrites was investigated using a microscope equipped with a fluorescence spectrophotometer. Fluorescent particles were observed in powdered CM2 carbonaceous chondrites (Y-74662, Y-7791198, and Murchison) without carbon enrichment by acid treatments. Although it was difficult to find fluorescent particles in powdered sample of C3 chondrites (ALH-77307, Y-791717, and Allende) without acid treatments, many fluorescent particles were observed after carbon enrichment by acid treatments. Fluorescence of coronene and shock-altered graphite were observed using the same microscope and the same conditions as those for carbonaceous chondrites.

  11. Search for Nucleosynthetic Cadmium Isotope Variations in Bulk Carbonaceous Chondrites

    NASA Astrophysics Data System (ADS)

    Toth, E. R.; Schönbächler, M.; Friebel, M.; Fehr, M. A.

    2016-08-01

    New high-precision Cd isotope data will be presented for bulk carbonaceous chondrites, such as Allende and Murchison. Volatile element isotope anomalies and their potential nucleosynthetic sources will be discussed.

  12. Shock metamorphism of carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  13. Nucleosynthetic strontium isotope anomalies in carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  14. Ion irradiation of carbonaceous chondrites for a Vis-IR space-weathering study on primitive objects: CV Allende and CM Murchison

    NASA Astrophysics Data System (ADS)

    Lantz, C.; Brunetto, R.

    2014-07-01

    The exposition of airless bodies to the harsh spatial environment in which they evolve (solar ion irradiation, micrometeorite bombardment, etc.) leads to surface alterations affecting the compositional interpretation made from spectra. This effect is known as space weathering (SW). A lot of studies have been made of SW on high-albedo asteroids [1], but little is known about SW of carbonaceous asteroids as previous studies have struggled to define a general spectral trend among dark surfaces [2]. In order to understand the influence of SW on primitive asteroids (while waiting for sample returns), we conduct laboratory simulations on meteorites: the goal of this work is to provide a model of the spectral alterations caused by SW of CM meteorite parent bodies and to assist OSIRIS-REx/NASA and Hayabusa-2/JAXA asteroid sample-return missions. Here we present irradiations of the Allende and Murchison meteorites exposed to 40 keV He^{+} and Ar^{+} ions, as a simulation of solar-wind irradiation of primitive bodies surfaces, using different fluences up to 3.10^{16} ions/cm^{2} (implantation platform SIDONIE at CSNSM Orsay) corresponding to short timescales of ˜10^{3}-10^{4} yrs in the main asteroid belt. Samples were analyzed ex situ before and after irradiation using visible to far-IR (0.4-50 μ m) reflectance spectroscopy. Reflectance spectra where acquired through fibers, allowing measurements at different phase angles. Allende and Murchison show different spectral behaviors after irradiation. Similarly to what has been observed in previous experiments [3], a reddening and darkening of Vis-NIR reflectance spectra is observed in the case of Allende. In the case of Murchison, spectral variations are negligible with respect to other spectral variations due to viewing geometry, grain size, and sample preparation, suggesting an explanation for the contradictory SW studies of dark asteroids. After irradiation on Allende, the infrared bands of the matrix olivine silicates

  15. 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.

  16. Graphitic carbon in the Allende meteorite: a microstructural study

    SciTech Connect

    Smith, P.P.K.; Buseck, P.R.

    1981-04-17

    High-resolution transmission electron microscopy shows that carbon in the Allende carbonaceous chondrite meteorite is predominantly a poorly crystalline graphite. Such material is of interest as an important carrier of the isotopically anomalous noble gases found in carbonaceous chondrites.

  17. Graphitic carbon in the Allende meteorite: a microstructural study.

    PubMed

    Smith, P P; Buseck, P R

    1981-04-17

    High-resolution transmission electron microscopy, shows that carbon in the Allende carbonaceous chondrite meteorite is predominantly a poorly crystalline graphite. Such material is of interest as an important carrier of the isotopically anomalous noble gases found in carbonaceous chondrites.

  18. High-temperature condensates in carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Grossman, L.

    1977-01-01

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

  19. Extraterrestrial Nucleobases in Carbonaceous Chondrites

    NASA Astrophysics Data System (ADS)

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

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

  20. Carbonaceous Chondrite Clasts in HED Achondrites

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  1. Electron microscopy of carbonaceous matter in Allende acid residues

    NASA Technical Reports Server (NTRS)

    Lumpkin, G. R.

    1982-01-01

    On the basis of characteristic diffuse ring diffraction patterns, much of the carbonaceous matter in a large suite of Allende acid residues has been identified as a variety of turbostratic carbon. Crystallites of this phase contain randomly stacked sp(2) hybridized carbon layers and diffraction patterns resemble those from carbon black and glassy carbon. Carbynes are probably absent, and are certainly restricted to less than 0.5% of these acid residues. The work of Ott et al. (1981) provides a basis for the possibility that turbostratic carbon is a carrier of noble gases, but an additional component - amorphous carbon - may be necessary to explain the high release temperatures of noble gases as well as the glassy character of many of the carbonaceous particles. Carbynes are considered to be questionable as important carriers of noble gases in the Allende acid residues.

  2. Electron microscopy of carbonaceous matter in Allende acid residues

    NASA Astrophysics Data System (ADS)

    Lumpkin, G. R.

    On the basis of characteristic diffuse ring diffraction patterns, much of the carbonaceous matter in a large suite of Allende acid residues has been identified as a variety of turbostratic carbon. Crystallites of this phase contain randomly stacked sp(2) hybridized carbon layers and diffraction patterns resemble those from carbon black and glassy carbon. Carbynes are probably absent, and are certainly restricted to less than 0.5% of these acid residues. The work of Ott et al. (1981) provides a basis for the possibility that turbostratic carbon is a carrier of noble gases, but an additional component - amorphous carbon - may be necessary to explain the high release temperatures of noble gases as well as the glassy character of many of the carbonaceous particles. Carbynes are considered to be questionable as important carriers of noble gases in the Allende acid residues.

  3. Lithium isotope compositions of chondrules, CAI and a dark inclusion from Allende and ordinary chondrites

    NASA Astrophysics Data System (ADS)

    Seitz, Hans-Michael; Zipfel, Jutta; Brey, Gerhard P.; Ott, Ulrich

    2012-05-01

    Bulk carbonaceous and ordinary chondrites have distinct Li isotope compositions, indicating the existence of local reservoirs and distinct formation conditions in the early solar system. These differences may be also recorded in the components that compose chondrites. Here, Li concentrations and Li isotope compositions of 89 chondrules, 10 CAI and 1 dark inclusion (DI) from the Allende (CV3) meteorite and from 5 ordinary chondrites of low petrologic types Semarkona, Bishunpur, Saratov, Bjurböle and Bremervörde are presented. In general, chondrules have highly variable Li isotope compositions, ranging from δ7Li of - 8.5 to + 10‰, whereby the mean isotope composition of chondrules separated from a single chondrite is slightly lighter than its bulk. Remarkable, however, are the differences in Li concentrations between bulk chondrite and chondrules. Of the entire set studied here, 98% of the chondrules have significantly lower Li abundances (in the range of 0.2 to 0.75 μg/g) than their hosts (typically around 1.5 μg/g). Our results indicate that Li elemental and isotopic fractionation has not occurred extensively during chondrule formation. Low, but highly variable Li abundances as well as the relatively large range in Li isotopes point to small-scale heterogeneities in the chondrule-forming reservoir. With respect to Li, such a non-chondritic reservoir is unique to all chondrules. The compositional differences in Li isotopes between bulk carbonaceous and ordinary chondrites (Seitz et al., 2007) are likely to be the result of mixing chondrules, CAI and matrix in different proportions.

  4. Exposure ages of carbonaceous chondrites, 1

    NASA Technical Reports Server (NTRS)

    Nishiizumi, K.; Arnold, J. R.; Caffee, M. W.; Finkel, R. C.; Southon, J. R.; Nagai, H.; Honda, M.; Sharma, P.; Imamura, M.; Kobayashi, K.

    1993-01-01

    The recent exposure histories of carbonaceous chondrites have been investigated using cosmogenic radionuclides. Our results may indicate a clustering of exposure ages of C1 and C2 chondrites into two peaks, 0.2 My and 0.6 My, perhaps implying two collisional events of Earth-crossing parent bodies. Among carbonaceous chondrites are some having short exposure ages which Mazor et al. hypothesized cluster into a small number of families. This hypothesis is based on spallogenic Ne-21 exposure ages, which in some instances are difficult to determine owing to the large amounts of trapped noble gases in carbonaceous chondrites. Also, since Ne-21 is stable, it integrates a sample's entire exposure history, so meteorites with complex exposure histories are difficult to understand using exclusively Ne-21. Cosmogenic radionuclides provide an alternative means of determining the recent cosmic ray exposure duration. To test the hypothesis of Mazor et al. we have begun a systematic investigation of exposure histories of Antarctic and non-Antarctic carbonaceous chondrites especially C2s.

  5. 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.

  6. Isotopic composition and concentration of sulfur in carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Gao, X.; Thiemens, M. H.

    1993-07-01

    New sulfur isotopic ratio measurements are reported for seven carbonaceous chondrites. Newly developed procedures permit measurement of delta S-33, delta S-34, and delta S-36 at precisions significantly greater than previously reported. A search for S-36 nucleosynthetic anomalies coproduced with anomalies in, for example, Ti-50 and Ca-48 was negative. The high endemic sulfur concentration probably dilutes any S-36 anomaly, and separation of individual sulfur phases may be needed to identify S-36 carrier phases. Large internal isotopic variations are observed, deriving from parent body and possibly nebular processes. Chondrule separates from Allende demonstrate isotopic compositions which vary as a function of diameter. High-temperature gas-solid exchange and a two-component mixing model may account for the observations. High-resolution isotopic data and structural information are reported for organic sulfur compounds separated by chemical extractions. The insoluble organics appear to be of either aliphatic or alicyclic structure and are dominant phases.

  7. Spectrum of carbonaceous-chondrite fission xenon

    NASA Technical Reports Server (NTRS)

    Clayton, D. D.

    1976-01-01

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

  8. Experimental Aqueous Alteration of the Allende CV3 Chondrite

    NASA Astrophysics Data System (ADS)

    Tomeoka, K.; Kojima, T.

    1995-09-01

    Aqueous alteration is an important process that prevailed in the early solar system. In order to better understand the aqueous alteration processes and conditions, we embarked in hydrothermal alteration experiments of the Allende CV3 chondrite. We here present the first results of our experiments. Samples of Allende were sealed in gold tubes with 1-N HCl and heated in a reactor vessel at 450 degrees C and 800 bars for 4 to 6 weeks. Thin sections were made from the run products and were observed and analyzed by a scanning electron microscope equipped with an EDS spectrometer. Our experiments produced remarkable alteration textures in the Allende chondrite. Parts of internal areas of most of the chondrules are replaced by brownish-to-greenish phyllosilicate, exhibiting an appearance closely similar to the altered ("spinach"-bearing) chondrules in CM chondrites. Fractures and interstices in chondrules and matrix, up to 20 micrometers in width and 1 mm in length, are filled with phyllosilicate, producing remarkable veins similar to those observed in CI chondrites. Mainly two kinds of phyllosilicates were produced. One contains major Mg and Fe and has compositions similar to Fe-rich saponite. This is the most common phyllosilicate that occurs in both chondrules and matrix; it is primarily formed by replacing olivine and low-Ca pyroxene. The other kind of phyllosilicate contains major Mg and Fe and variable Al; it is probably a mixture of two phases, so we tentatively call it high-Al phyllosilicates (HAP). HAP occurs mainly in chondrule mesostasis, where it is formed by replacing mesostasis glass. Chondrules and aggregates are altered from their edges to inward. Olivine in outer areas of chondrules and aggregates are enriched in Fe, and most of individual olivine grains show strong Fe-Mg zoning, indicating substantial Fe was added from matrix to chondrules. Mesostasis in central areas is preferentially replaced by HAP, while that in outer areas is replaced by saponite

  9. Grain size distribution of the matrix in the Allende chondrite

    NASA Astrophysics Data System (ADS)

    Toriumi, M.

    1989-03-01

    Results are presented from analytical TEM, high-resolution TEM, and SEM studies of the Allende chondrite, showing that the matrix consists of very fine-grained Fe-rich olivine, Ca-poor and Fe-rich clinopyroxene, Fe-rich spinel, and Ni-bearing troilite. Slightly sintered and non-sintered very fine-grained aggregates are observed. The results suggest that the coarse-grained olivine aggregates experienced a heating event, whereas the ultrafine-grained aggregates did not. The size and frequency distributions of matrix grains are measured. The frequency distribution displays a long-term tail with power law and a log-normal pattern with a peak at 5 nm in the range from 1 to 10 nm. This suggests that the fine-grained matrix was probably formed at conditions far from equilibrium in the protosolar cloud.

  10. Evidence of Microfossils in Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.; Rozanov, Alexei Y.; Zhmur, S. I.; Gorlenko, V. M.

    1998-01-01

    Investigations have been carried out on freshly broken, internal surfaces of the Murchison, Efremovka and Orgueil carbonaceous chondrites using Scanning Electron Microscopes (SEM) in Russia and the Environmental Scanning Electron Microscope (ESEM) in the United States. These independent studies on different samples of the meteorites have resulted in the detection of numerous spherical and ellipsoidal bodies (some with spikes) similar to the forms of uncertain biogenicity that were designated "organized elements" by prior researchers. We have also encountered numerous complex biomorphic microstructures in these carbonaceous chondrites. Many of these complex bodies exhibit diverse characteristics reminiscent of microfossils of cyanobacteria such as we have investigated in ancient phosphorites and high carbon rocks (e.g. oil shales). Energy Dispersive Spectroscopy (EDS) analysis and 2D elemental maps shows enhanced carbon content in the bodies superimposed upon the elemental distributions characteristic of the chondritic matrix. The size, distribution, composition, and indications of cell walls, reproductive and life cycle developmental stages of these bodies are strongly suggestive of biology' These bodies appear to be mineralized and embedded within the meteorite matrix, and can not be attributed to recent surface contamination effects. Consequently, we have interpreted these in-situ microstructures to represent the lithified remains of prokaryotes and filamentous cyanobacteria. We also detected in Orgueil microstructures morphologically similar to fibrous kerite crystals. We present images of many biomorphic microstructures and possible microfossils found in the Murchison, Efremovka, and Orgueil chondrites and compare these forms with known microfossils from the Cambrian phosphate-rich rocks (phosphorites) of Khubsugul, Northern Mongolia.

  11. Ion irradiation of carbonaceous chondrites as a simulation of space weathering on C-complex asteroids

    NASA Astrophysics Data System (ADS)

    Lantz, C.; Brunetto, R.; Barucci, M. A.; Bachelet, C.; Baklouti, D.; Bourçois, J.; Dartois, E.; Duprat, J.; Duret, P.; Engrand, C.; Godard, M.; Ledu, D.; Mivumbi, O.; Fornasier, S.

    2015-10-01

    We are investigating the effects of space weathering on primitive asteroids using ion irradiation on their meteoritic analogs. To do so, we exposed several carbonaceous chondrites (CV Allende, COs Lancé and Frontier Mountain 95002, CM Mighei, CI Alais, and ungrouped Tagish Lake) to 40 keV He+ ions as a simulation of solar wind irradiation using fluences up to 6.1016 ions/cm2 (implantation platform IRMA at CSNSM Orsay). As a test for our new experimental setup, we also studied samples of olivine and diopside. We confirm the reddening and darkening trends on S-type objects, but carbonaceous chondrites present a continuum of behaviors after ion irradiation as a function of the initial albedo and carbon content: from red to blue and from dark to bright.

  12. Manganese chromium isotope systematics of carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Shukolyukov, A.; Lugmair, G. W.

    2006-10-01

    In this article we present the results of Cr isotope investigations of different types of carbonaceous chondrites and of the pallasite Eagle Station. The 53Cr/ 52Cr ratios in the bulk samples of carbonaceous chondrites are correlated with 55Mn/ 52Cr ratios. The slope of the correlation line yields a 53Mn/ 55Mn ratio of (8.5 ± 1.5) × 10 - 6 at the time of Mn/Cr fractionation. Mapping this ratio onto an absolute time scale yields a time for this event of 4568.1 + 0.8/- 1.1 Ma ago. This time is very similar to the formation age of Efremovka CAIs of 4567.2 ± 0.6 Ma [Y. Amelin, A. N. Krot, I. D. Hutcheon, A. A. Ulyanov, Lead isotopic ages of chondrules and calcium-aluminum-rich inclusions, Science 297 (2002) 1678-1683], to a time of the chondrule formation of 4568 ± 1 Ma ago [L.E. Nyquist, D. Lindstrom, D. Mittlefehldt, C.-Y. Shih, H. Wiesmann, S. Wentworth, R. Martinez, Manganese-chromium formation intervals for chondrules from the Bishunpur and Chainpur meteorites, Meteorit. Planet. Sci. 36 (2001) 911-938], which, most likely, constrains early global high-temperature Mn/Cr fractionation in a nebular setting. The bulk samples of carbonaceous chondrites exhibit clear 54Cr excesses ( 54Cr *) that are correlated with the 53Cr excesses ( 53Cr *) and also with Mn/Cr ratios. One possible explanation of this correlation is that 54Cr * is also radiogenic, like 53Cr *, and was formed by the decay of the short-lived parent radionuclide 54Mn. The very short half-life of 54Mn of 312 days would require that both short-lived radionuclides 53Mn and 54Mn were generated locally in spallation reactions during the early period of an active sun. The alternative and possibly more plausible explanation is the heterogeneous addition of presolar material. The presolar component, enriched in 54Cr, is mostly contained in the matrix of carbonaceous chondrites. The relative amount of matrix decreases in the sequence CI > CM > CO,CV. A large proportion of Mn is associated with the matrix while

  13. 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.

  14. 13C NMR spectroscopy of the insoluble carbon of carbonaceous chondrites.

    PubMed

    Cronin, J R; Pizzarello, S; Frye, J S

    1987-01-01

    13C NMR spectra have been obtained of the insoluble carbon residues resulting from HF-digestion of three carbonaceous chondrites, Orgueil (C1), Murchison (CM2), and Allende (CV3). Spectra obtained using the cross polarization magic-angle spinning technique show two major features attributable respectively to carbon in aliphatic/olefinic structures. The spectrum obtained from the Allende sample was weak, presumably as a consequence of its low hydrogen content. Single pulse excitation spectra, which do not depend on 1H-13C polarization transfer for signal enhancement were also obtained. These spectra, which may be more representative of the total carbon in the meteorite samples, indicate a greater content of carbon in aromatic/olefinic structures. These results suggest that extensive polycyclic aromatic sheets are important structural features of the insoluble carbon of all three meteorites. The Orgueil and Murchison materials contain additional hydrogenated aromatic/olefinic and aliphatic groups.

  15. 13C NMR spectroscopy of the insoluble carbon of carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Cronin, J. R.; Pizzarello, S.; Frye, J. S.

    1987-01-01

    13C NMR spectra have been obtained of the insoluble carbon residues resulting from HF-digestion of three carbonaceous chondrites, Orgueil (C1), Murchison (CM2), and Allende (CV3). Spectra obtained using the cross polarization magic-angle spinning technique show two major features attributable respectively to carbon in aliphatic/olefinic structures. The spectrum obtained from the Allende sample was weak, presumably as a consequence of its low hydrogen content. Single pulse excitation spectra, which do not depend on 1H-13C polarization transfer for signal enhancement were also obtained. These spectra, which may be more representative of the total carbon in the meteorite samples, indicate a greater content of carbon in aromatic/olefinic structures. These results suggest that extensive polycyclic aromatic sheets are important structural features of the insoluble carbon of all three meteorites. The Orgueil and Murchison materials contain additional hydrogenated aromatic/olefinic and aliphatic groups.

  16. Carbonaceous chondrites and the origin of life

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  17. Organic analysis of the Antarctic carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  18. Petrographic, Chemical and Spectroscopic Data on Thermally Metamorphosed Carbonaceous Chondrites

    NASA Astrophysics Data System (ADS)

    Tonui, E. K.; Zolensky, M. E.; Hiroi, T.; Wang, M.-S.; Lipschutz, M. E.

    2002-03-01

    First comprehensive description of aqueous alteration and thermal metamorphism in carbonaceous chondrites. Petrographic evidence has been checked against labile trace element temperatures. Spectroscopic data reveals the level of dehydration and possible relationship to primitive asteroids.

  19. Analogues for Wild2: Carbonaceous Chondrites Shot into Aerogel

    NASA Astrophysics Data System (ADS)

    Hicks, L. J.; Bridges, J. C.; MacArthur, J. L.; Wickham-Eade, J. E.; Price, M. C.; Burchell, M. J.; Butterworth, A. L.; Baker, S. H.

    2016-08-01

    Comet Wild2 particles show similarities to carbonaceous chondrites. We compare Wild2 grains to analogue shots of CV3 and CR2 powders in aerogel tracks, using the same techniques, to make accurate comparisons.

  20. 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

  1. Opaque Assemblages in CK and CV Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Neff, K. E.; Righter, K.

    2006-01-01

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

  2. Amoeboid olivine aggregates from CH carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Krot, Alexander N.; Park, Changkun; Nagashima, Kazuhide

    2014-08-01

    Amoeboid olivine aggregates (AOAs) in CH carbonaceous chondrites are texturally and mineralogically similar to those in other carbonaceous chondrite groups. They show no evidence for alteration and thermal metamorphism in an asteroidal setting and consist of nearly pure forsterite (Fa<3; in wt%, CaO = 0.1-0.8, Cr2O3 = 0.04-0.48; MnO < 0.5), anorthite, Al-diopside (in wt%, Al2O3 = 0.7-8.1; TiO2 < 1), Fe,Ni-metal, spinel, and, occasionally, low-Ca pyroxene (Fs1Wo2-3), and calcium-aluminum-rich inclusions (CAIs). The CAIs inside AOAs are composed of hibonite, grossite, melilite (Åk13-44), spinel, perovskite, Al,Ti-diopside (in wt%, Al2O3 up to 19.6; TiO2 up to 13.9), and anorthite. The CH AOAs, including CAIs within AOAs, have isotopically uniform 16O-rich compositions (average Δ17O = -23.4 ± 2.3‰, 2SD) and on a three-isotope oxygen diagram plot along ∼slope-1 line. The only exception is a low-Ca pyroxene-bearing AOA 1-103 that shows a range of Δ17O values, from -24‰ to -13‰. Melilite, grossite, and hibonite in four CAIs within AOAs show no evidence for radiogenic 26Mg excess (δ26Mg). In contrast, anorthite in five out of six AOAs measured has δ26Mg corresponding to the inferred initial 26Al/27Al ratio of (4.3 ± 0.7) × 10-5, (4.2 ± 0.6) × 10-5, (4.0 ± 0.3) × 10-5, (1.7 ± 0.2) × 10-5, and (3.0 ± 2.6) × 10-6. Anorthite in another AOA shows no resolvable δ26Mg excess; an upper limit on the initial 26Al/27Al ratio is 5 × 10-6. We infer that CH AOAs formed by gas-solid condensation and aggregation of the solar nebula condensates (forsterite and Fe,Ni-metal) mixed with the previously formed CAIs. Subsequently they experienced thermal annealing and possibly melting to a small degree in a 16O-rich gaseous reservoir during a brief epoch of CAI formation. The low-Ca pyroxene-bearing AOA 1-103 may have experienced incomplete melting and isotope exchange in an 16O-poor gaseous reservoir. The lack of resolvable δ26Mg excess in melilite, grossite, and

  3. Distinct Purine Distribution in Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  4. Spectral reflectance properties of carbonaceous chondrites: 2. CM chondrites

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

    We have examined the spectral reflectance properties and available modal mineralogies of 39 CM carbonaceous chondrites to determine their range of spectral variability and to diagnose their spectral features. We have also reviewed the published literature on CM mineralogy and subclassification, surveyed the published spectral literature and added new measurements of CM chondrites and relevant end members and mineral mixtures, and measured 11 parameters and searched pair-wise for correlations between all quantities. CM spectra are characterized by overall slopes that can range from modestly blue-sloped to red-sloped, with brighter spectra being generally more red-sloped. Spectral slopes, as measured by the 2.4:0.56 μm and 2.4 μm:visible region peak reflectance ratios, range from 0.90 to 2.32, and 0.81 to 2.24, respectively, with values <1 indicating blue-sloped spectra. Matrix-enriched CM spectra can be even more blue-sloped than bulk samples, with ratios as low as 0.85. There is no apparent correlation between spectral slope and grain size for CM chondrite spectra - both fine-grained powders and chips can exhibit blue-sloped spectra. Maximum reflectance across the 0.3-2.5 μm interval ranges from 2.9% to 20.0%, and from 2.8% to 14.0% at 0.56 μm. Matrix-enriched CM spectra can be darker than bulk samples, with maximum reflectance as low as 2.1%. CM spectra exhibit nearly ubiquitous absorption bands near 0.7, 0.9, and 1.1 μm, with depths up to 12%, and, less commonly, absorption bands in other wavelength regions (e.g., 0.4-0.5, 0.65, 2.2 μm). The depths of the 0.7, 0.9, and 1.1 μm absorption features vary largely in tandem, suggesting a single cause, specifically serpentine-group phyllosilicates. The generally high Fe content, high phyllosilicate abundance relative to mafic silicates, and dual Fe valence state in CM phyllosilicates, all suggest that the phyllosilicates will exhibit strong absorption bands in the 0.7 μm region (due to Fe 3+-Fe 2+ charge

  5. Differences in isotopic composition of carbonaceous components in enstatite chondrites

    NASA Astrophysics Data System (ADS)

    Grady, M. M.; Wright, I. P.; Carr, R. H.; Poths, J.; Pillinger, C. T.

    1988-02-01

    Carbon stable isotopic composition of the major carbonaceous component in enstatite chondrites varies with petrologic type. Investigation of a suite of HF/HCl-resistant residues has shown that this variation is due to an inherent difference in delta(C-13) of the carbon, and is not a result of the presence of small amounts of isotopically anomalous carbon-bearing components. These latter do occur in type EH3 and EH4 chondrites, in concentrations similar to those found in C1 and C2 carbonaceous chondrites. Combustion of the major carbon component (apparently elemental carbon, not necessarily graphite) occurs at relatively higher temperatures in enstatite chondrites of increasing petrologic type. This is considered to reflect an increase in crystallinity or ordering of the carbonaceous component, and is a measure of the degree of thermal processing to which the meteorites have been subjected during accretion and/or metamorphism.

  6. Carbonaceous objects resembling nannobacteria in the Allende meteorite

    NASA Astrophysics Data System (ADS)

    Folk, Robert L.; Lynch, F. Leo

    1998-07-01

    The carbon in Allende consists of balls ranging form 30 to 150 nm in diameter.Most are spheres, but some ovoid to worm- like forms occur. Grape-like clumps and rosary-like chains are the most dramatic mimics of terrestrial bacterial colonies. We propose that the carbon balls in Allende represent roasted corpses of nanobacteria because of their resemblance to nanobacteria on earth.

  7. New SSMS Techniques for the Determination of Rhodium and Other Platinum- Group Elements in Carbonaceous Chondrites

    NASA Astrophysics Data System (ADS)

    Jochum, K. P.; Seufert, H. M.

    1995-09-01

    We have developed new spark source mass spectrometric (SSMS) techniques for simultaneous analysis of platinum-group elements (PGE) together with other trace elements in stony meteorites. We have measured elemental abundances of Rh, Ru, Os, Ir, Pt, Au in carbonaceous chondrites of different types including the two CI chondrites Orgueil and Ivuna. These data are relevant for the determination of solar-system abundances. Whereas the solar-system abundances of most PGE are well known, this is not the case for Rh, and no literature data exist for carbonaceous chondrites, mainly because of analytical difficulties. The SSMS techniques include new calibration procedures and the use of a recently developed multi-ion counting (MIC) system [1]. The mono-isotopic element Rh and the other PGE were determined by using internal standard elements (e.g., Nd, U) that were measured by isotope dilution in the same sample electrode material. The data were calibrated with certified standard solutions of PGE which were doped on trace-element poor rock samples. Ion abundances were measured using both the conventional photoplate detection and the ion-counting techniques. The new MIC technique that uses up to 20 small channeltrons for ion counting measurements has the advantage of improved precision, detection limits and analysis time compared to photoplate detection. Tab. 1 shows the Rh analyses for the meteorites Orgueil, Ivuna, Murchison, Allende and Karoonda obtained by conventional photoplate detection. These are the first Rh results for carbonaceous chondrites. The data for the two CI chondrites Orgueil and Ivuna are identical and agree within 4 % with the CI estimate of Anders and Grevesse [2] which was derived indirectly from analyses for H-chondrites. The PGE Os, Ir, Pt, Au and W, Re, Th, U concentrations were determined by both detection systems. Data obtained with the MIC system are more precise (about 4% for concentrations in the ppb range) compared to the photoplate detection

  8. Phyllosilicates in the Carbonaceous Chondrite Breccia Kaidun

    NASA Astrophysics Data System (ADS)

    Yang, S. V.; Zolensky, M.; Golden, D. C.; Ming, D. W.; Ivanov, A.

    1993-07-01

    observed. In contrast, most reported Kaidun and CR lithologies have approximately subequal amounts of saponite and serpentine in matrix. Phyllosilicates in Kaidun are commonly associated with sulfides; no phyllosilicates have been observed as direct overgrowths on olivine or pyroxene. Microprobe analyses of coarse-grained Kaidun saponites indicate that the majority of the exchangeable cations in the saponites studied are Mg2+ and Ca2+, with mior Na+. However, since the results of this study suggest that the saponite in Kaidun has a highly charged interlayer environment, one might speculate that any ammonium (NH4+) if present in the original parent body atmosphere or the reacting solution might be fixed in the interlayers. High- charge smectites are known to fix ammonium ions from solution [3]. There is spectroscopic evidence for ammonium-bearing phases on asteroid Ceres 1 [4]. Most carbonaceous chondrites are known to contain relatively high amounts of nitrogen (up to 3000 ppm) [5]. In order to detect if any of this N is in NH4+ form in the interlayers, we set up our Cameca electron microprobe to detect the nitrogen K-alpha X-ray peak using an ODPB crystal of a wavelength dispersive spectrometer. No nitrogen peak was positively identified on the carbonaceous matrix, nor on any saponites, although it is possible that the electron beam neutralized and evaporated any NH4+ cations before detection. In conclusion, the phyllosilicates in Kaidun are heterogeneously distributed from clast to clast, with highly charged saponite predominating in some clasts; serpentine and saponite are more nearly equally abundant in other clasts. No nitrogen was positively detected in the matrix or in any components in Kaidun by the electron microprobe in this study, although further studies of Kaidun phyllosilicates are in progress. References: [1] Zolensky M. and McSween H. Y. Jr. (1988) in Meteorites and the Early Solar System, Univ. of Arizona, 114-143. [2] Ming D. W. et. al. (1992) LPSC XXIII

  9. Origin of magnetite and pyrrhotite in carbonaceous chondrites

    USGS Publications Warehouse

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

    1975-01-01

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

  10. Hydrated interplanetary dust particle linked with carbonaceous chondrites?

    NASA Technical Reports Server (NTRS)

    Tomeoka, K.; Buseck, P. R.

    1985-01-01

    The results of transmission electron microscope observations of a hydrated interplanetary dust particle (IDP) containing Fe-, Mg-rich smectite or mica as a major phase are reported. The sheet silicate appears to have formed by alteration of anhydrous silicates. Fassaite, a Ca, Al clinopyroxene, also occurs in this particle, and one of the crystals exhibits solar-flare tracks, clearly indicating that it is extraterrestrial. Fassaite is a major constituent of the Ca-, Al-rich refractory inclusions found in the carbonaceous chondrites, so its presence in this particle suggests that there may be a link between hydrated IDPs and carbonaceous chondrites in the early history of the solar system.

  11. Carbonaceous Chondrite Fragments in the Polymict Eucrite Yamato 791834

    NASA Technical Reports Server (NTRS)

    Buchanan, P. C.; Zolensky, M. E.

    2003-01-01

    Buchanan et al. and Zolensky et al. described carbonaceous chondrite fragments in a variety of howardites and concluded that the majority are CM2 and CR2 materials. Gounelle et al. also described similar, but very small, fragments in these meteorites. These clasts are important because they represent materials that were in orbital proximity to the HED parent body (4 Vesta) and they may be similar to the primitive materials that originally accreted to form this body. The present study describes two carbonaceous chondrite clasts in the Yamato 791834 (Y791834) polymict eucrite.

  12. Pore Water Convection in Carbonaceous Chondrite Planetesimals

    NASA Astrophysics Data System (ADS)

    Travis, B. J.; Schubert, G.

    2004-12-01

    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. Asteroids of the inner solar system are probably present-day representatives of the early 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 equation of state for water and ice. We have simulated the evolution of heating, melting of ice, subsequent flow and eventual re-freezing for several examples of CC planetesimals. For a reference simulation, we use typical values from meteorite analyses: 20 % porosity, 1 darcy permeability (~10-12 m2), 3x10-8 wt fraction of 26Al, rock density of 3000 kg/m3, rock specific heat of 1000 J/kg/K, body radius of 50 km, solid rock thermal conductivity of 3 W/m/K. For the

  13. Petrology of Amoeboid Olivine Aggregates in Antarctic CR Chondrites: Comparison With Other Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

    Amoeboid olivine aggregates (AOAs) are important refractory components of carbonaceous chondrites and have been interpreted to represent solar nebular condensates that experienced high-temperature annealing, but largely escaped melting. In addition, because AOAs in primitive chondrites are composed of fine-grained minerals (forsterite, anorthite, spinel) that are easily modified during post crystallization alteration, the mineralogy of AOAs can be used as a sensitive indicator of metamorphic or alteration processes. AOAs in CR chondrites are particularly important because they show little evidence for secondary alteration. In addition, some CR AOAs contain Mn-enriched forsterite (aka low-iron, Mn-enriched or LIME olivine), which is an indicator of nebular formation conditions. Here we report preliminary results of the mineralogy and petrology of AOAs in Antarctic CR chondrites, and compare them to those in other carbonaceous chondrites.

  14. Spectral reflectance properties of carbonaceous chondrites: 8. “Other” carbonaceous chondrites: CH, ungrouped, polymict, xenolithic inclusions, and R chondrites

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

    We have analyzed reflectance spectra (0.3-2.5 μm) of a number of ungrouped or tentatively grouped carbonaceous chondrites (CCs), possible CC-type xenoliths in an aubrite (Cumberland Falls) and a howardite (PRA 04401), a CH chondrite (PCA 91467), a CC polymict breccia (Kaidun), and some R chondrites. The best approach to analysis relies largely on characterizing spectrally active phases - i.e., those phases that contribute diagnostic absorption features, involving absorption band wavelength position, band depth, shape of absorption features, combined with albedo and spectral slope. Mafic silicate (hydrous and/or anhydrous) absorption features are ubiquitous in the CCs and R chondrites we have examined. Combining information on these features along with albedo and spectral slopes allows reasonable inferences to be made concerning their uniqueness. Reflectance spectra of Coolidge show contributions from both olivine and Fe oxyhydroxides (from terrestrial weathering), and its high reflectance and mafic silicate band depths are consistent with a petrologic grade >3 and inconsistent with CVs. The CC nature of the Cumberland Falls inclusions from spectral analysis is inconclusive, but they do exhibit spectral features consistent with their overall mineralogy. DaG 430, which has petrologic characteristics of both CV and CK chondrites, has a spectrum that is not fully consistent with either group. The spectrum of EET 96029 is consistent with some, but not all CM2 chondrites. GRO 95566, a meteorite with some affinities to CM2s, most resembles the Renazzo CR2 chondrite, consistent with their similar mineralogies, and its spectral properties can be related to its major mineralogic characteristics. Spectra of Kaidun are most consistent with CR chondrites, which form the bulk of this meteorite. The reflectance spectrum of MCY 92005 is consistent with its recent classification as a CM2 chondrite. The R3 chondrite MET 01149 shares many characteristics with CKs, but differs in

  15. Manganese-Chromium Isotope Systematics of Ivuna, Kainsaz and Other Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Shukolyukov, A.; Lugmair, G. W.; Bogdanovski, O.

    2003-01-01

    We have shown earlier that the bulk samples of carbonaceous chondrites [CC] reveal excesses in both Cr-53 (Cr-53*) and Cr-54 (Cr-54*) as compared to the terrestrial standard value. The Cr-53/52 ratios in bulk samples of Orgueil (CI), Murray (CM), Allende (CV), and the Bencubbin/CH-like meteorite Hammadah Al Hambra 237 (HH237) are correlated with the respective Mn/Cr ratios. In contrast to CC, HH237 is characterized by a deficit of Cr-53 (-0.15 +/- 0.10(epsilon)) at a low Mn/Cr ratio of 0.07. The HH237 data point, however, falls on the CC line. Here we report new Mn-53 - Cr-53 results for the CC Kainsaz (CO) and Ivuna (CI).

  16. Comets, carbonaceous chondrites, and interstellar clouds: Condensation of carbon

    NASA Technical Reports Server (NTRS)

    Field, G. B.

    1979-01-01

    Comets, carbonaceous chondrites, and interstellar clouds are discussed in relation to information on interstellar dust. The formation and presence of carbon in stars, comets, and meteorites is investigated. The existence of graphite in the interstellar medium, though it is predicted from thermodynamic calculations, is questioned and the form of carbon contained in comets is considered.

  17. Plagioclase-rich inclusions in carbonaceous chondrite meteorites - Liquid condensates?

    NASA Technical Reports Server (NTRS)

    Wark, D. A.

    1987-01-01

    The characteristics and formation of coarse-grained, plagioclase-rich inclusions are investigated. The textures, mineralogical compositions, and initial Al-26/Al-27 ratios for the plagioclase-rich inclusions are described. It is observed that plagioclase-rich inclusions in carbonaceous chondrites are either Ca-Al-rich inclusions (CAIs) composed of 30-60 vol pct anorthite, and less than 35 vol pct Ti-Al-pyroxene and melilite, or CA chondrites composed of plagioclase, pyroxene, olivine, spinel, and melilite. It is observed that CA chondrules are chemically and mineralogically the most similar components shared by carbonaceous and ordinary chondrites. The textural changes observed in the inclusions are examined. The data reveal that the CAIs have three textural groups: coarse anorthite laths, equigranular anorthite and Ti-Al-pyroxene, and lacy Ti-Al-pyroxene and fine-grained anorthite.

  18. The Chromium Isotopic Composition of the Ungrouped Carbonaceous Chondrite Tagish Lake

    NASA Astrophysics Data System (ADS)

    Petitat, M.; Birck, J.-L.; Luu, T. H.; Gounelle, M.

    2011-07-01

    Early solar materials bear a variety of isotopic anomalies that reflect compositional differences deriving from distinct stellar nucleosynthetic processes. As shown in previous studies, the stepwise dissolution with increasing acid strengths of bulk rock carbonaceous chondrites liberates Cr with both excesses and deficits in 53Cr and 54Cr relative to the terrestrial standard. The magnitude of the 54Cr variations within a meteorite decreases in the sequence CI1 > CR2 > CM2 > CV3 > CO3 > CK4 and correlates with the degree of metamorphism of each carbonaceous chondrite class. This study shows that the Tagish Lake meteorite presents the highest excesses in 54Cr ever measured in a bulk silicate phase. According to this study, the Tagish Lake meteorite is composed of the least re-equilibrated material known at this time. The magnitude of 54Cr variation decreases now in the following sequence: Tagish Lake (ungrouped CI2) > Orgueil (CI1) > Murchison (CM2) > Allende (CV2). Moreover, this study shows that excesses in 53Cr relative to Earth can be interpreted as representing the extent of aqueous alteration on meteorite parent bodies. Finally, the high 54Cr anomalies measured in this meteorite make Tagish Lake one of the major targets to decipher the host of these anomalies.

  19. THE CHROMIUM ISOTOPIC COMPOSITION OF THE UNGROUPED CARBONACEOUS CHONDRITE TAGISH LAKE

    SciTech Connect

    Petitat, M.; Gounelle, M.; Birck, J.-L.; Luu, T. H.

    2011-07-20

    Early solar materials bear a variety of isotopic anomalies that reflect compositional differences deriving from distinct stellar nucleosynthetic processes. As shown in previous studies, the stepwise dissolution with increasing acid strengths of bulk rock carbonaceous chondrites liberates Cr with both excesses and deficits in {sup 53}Cr and {sup 54}Cr relative to the terrestrial standard. The magnitude of the {sup 54}Cr variations within a meteorite decreases in the sequence CI1 > CR2 > CM2 > CV3 > CO3 > CK4 and correlates with the degree of metamorphism of each carbonaceous chondrite class. This study shows that the Tagish Lake meteorite presents the highest excesses in {sup 54}Cr ever measured in a bulk silicate phase. According to this study, the Tagish Lake meteorite is composed of the least re-equilibrated material known at this time. The magnitude of {sup 54}Cr variation decreases now in the following sequence: Tagish Lake (ungrouped CI2) > Orgueil (CI1) > Murchison (CM2) > Allende (CV2). Moreover, this study shows that excesses in {sup 53}Cr relative to Earth can be interpreted as representing the extent of aqueous alteration on meteorite parent bodies. Finally, the high {sup 54}Cr anomalies measured in this meteorite make Tagish Lake one of the major targets to decipher the host of these anomalies.

  20. Kinetics of volatile extraction from carbonaceous chondrites: Dehydration of talc

    NASA Technical Reports Server (NTRS)

    Bose, Kunal; Ganguly, Jibamitra

    1991-01-01

    Carbonaceous chondrites are believed to be the primary constituents of near-Earth asteroids and Phobos and Deimos, and are potential resources of fuels that may be exploited for future planetary missions. Calculations of equilibrium phase relations suggest that talc (Ta) and antigorite (Ant) are likely to be the major hydrous phases in the C1 and C2 meteorites (Ganguly and Saxena, 1989), which constitute the most volatile rich classes of carbonaceous chondrites. The dehydration kinetics of talc are studied as a function of temperature, grain size, composition and fluid fugacity, as part of a systematic study of the reaction kinetics of the volatile bearing phases that are either known or likely to be present in carbonaceous chondrites. The dehydration kinetics were investigated at 1 bar, 775 to 875 C by monitoring the in-situ weight loss as a function of time of a natural talc. The talc platelets had a dimension of 0.8 to 1 micron. The run durations varied from 233.3 hours at 775 C (48 percent dehydration) to 20.8 hours at 875 C (80 pct. dehydration). The results can be adequately represented by a given rate equation. Theoretical analysis suggests that the reduction in the concentration of H2O in the environment of dehydrating talc, as would be encountered in processing chondritic materials, will have negligible effect on the rate of dehydration, unless there is a change of reaction mechanism owing to the presence of other volatile species.

  1. Spectral reflectance properties of carbonaceous chondrites: 1. CI chondrites

    NASA Astrophysics Data System (ADS)

    Cloutis, E. A.; Hiroi, T.; Gaffey, M. J.; Alexander, C. M. O.'D.; Mann, P.

    2011-03-01

    Existing reflectance spectra of CI chondrites (18 spectra of 3 CIs) have been augmented with new (18 spectra of 2 CIs) reflectance spectra to ascertain the spectral variability of this meteorite class and provide insights into their spectral properties as a function of grain size, composition, particle packing, and viewing geometry. Particle packing and viewing geometry effects have not previously been examined for CI chondrites. The current analysis is focused on the 0.3-2.5 μm interval, as this region is available for the largest number of CI spectra. Reflectance spectra of powdered CI1 chondrites are uniformly dark (<10% maximum reflectance) but otherwise exhibit a high degree of spectral variability. Overall spectral slopes range from red (increasing reflectance with increasing wavelength) to blue (decreasing reflectance with increasing wavelength). A number of the CI spectra exhibit weak (<5% deep) absorption bands that can be attributed to both phyllosilicates and magnetite. Very weak absorption bands attributable to other CI phases, such as carbonates, sulfates, and organic matter may be present in one or a few spectra, but their identification is not robust. We found that darker spectra are generally correlated with bluer spectral slopes: a behavior most consistent with an increasing abundance of fine-grained magnetite and/or insoluble organic material (IOM), as no other CI opaque phase appears able to produce concurrent darkening and bluing. Magnetite can also explain the presence of an absorption feature near 1 μm in some CI spectra. The most blue-sloped spectra are generally associated with the larger grain size samples. For incidence and emission angles <60°, increasing phase angle results in darker and redder spectra, particularly below ∼1 μm. At high incidence angles (60°), increasing emission angle results in brighter and redder spectra. More densely packed samples and underdense (fluffed) samples show lower overall reflectance than normally

  2. Delivery of dark material to Vesta via carbonaceous chondritic impacts

    NASA Astrophysics Data System (ADS)

    Reddy, Vishnu; Le Corre, Lucille; O'Brien, David P.; Nathues, Andreas; Cloutis, Edward A.; Durda, Daniel D.; Bottke, William F.; Bhatt, Megha U.; Nesvorny, David; Buczkowski, Debra; Scully, Jennifer E. C.; Palmer, Elizabeth M.; Sierks, Holger; Mann, Paul J.; Becker, Kris J.; Beck, Andrew W.; Mittlefehldt, David; Li, Jian-Yang; Gaskell, Robert; Russell, Christopher T.; Gaffey, Michael J.; McSween, Harry Y.; McCord, Thomas B.; Combe, Jean-Philippe; Blewett, David

    2012-11-01

    NASA’s Dawn spacecraft observations of Asteroid (4) Vesta reveal a surface with the highest albedo and color variation of any asteroid we have observed so far. Terrains rich in low albedo dark material (DM) have been identified using Dawn Framing Camera (FC) 0.75 μm filter images in several geologic settings: associated with impact craters (in the ejecta blanket material and/or on the crater walls and rims); as flow-like deposits or rays commonly associated with topographic highs; and as dark spots (likely secondary impacts) nearby impact craters. This DM could be a relic of ancient volcanic activity or exogenic in origin. We report that the majority of the spectra of DM are similar to carbonaceous chondrite meteorites mixed with materials indigenous to Vesta. Using high-resolution seven color images we compared DM color properties (albedo, band depth) with laboratory measurements of possible analog materials. Band depth and albedo of DM are identical to those of carbonaceous chondrite xenolith-rich howardite Mt. Pratt (PRA) 04401. Laboratory mixtures of Murchison CM2 carbonaceous chondrite and basaltic eucrite Millbillillie also show band depth and albedo affinity to DM. Modeling of carbonaceous chondrite abundance in DM (1-6 vol.%) is consistent with howardite meteorites. We find no evidence for large-scale volcanism (exposed dikes/pyroclastic falls) as the source of DM. Our modeling efforts using impact crater scaling laws and numerical models of ejecta reaccretion suggest the delivery and emplacement of this DM on Vesta during the formation of the ∼400 km Veneneia basin by a low-velocity (<2 km/s) carbonaceous impactor. This discovery is important because it strengthens the long-held idea that primitive bodies are the source of carbon and probably volatiles in the early Solar System.

  3. 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.

  4. Petrographic, chemical and spectroscopic evidence for thermal metamorphism in carbonaceous chondrites I: CI and CM chondrites

    NASA Astrophysics Data System (ADS)

    Tonui, Eric; Zolensky, Mike; Hiroi, Takahiro; Nakamura, Tomoki; Lipschutz, Michael E.; Wang, Ming-Sheng; Okudaira, Kyoko

    2014-02-01

    We present a comprehensive description of petrologic, chemical and spectroscopic features of thermally metamorphosed CI-like and CM (and CM-like) chondrites. Only two such CI chondrites have so far been discovered i.e. Y-86029 and Y-82162. Thermal metamorphism in these chondrites is apparent in their low contents of H2O, C and the most thermally labile trace elements, partial dehydration of matrix phyllosilicates and abundance of thermally decomposed Ca-Mg-Fe-Mn carbonates, which apparently resulted from heating of Mg-Fe carbonate precursors. The CM chondrites exhibit a wide range of aqueous and thermal alteration characteristics. This alteration was almost complete in Y-86720 and Y-86789, which also escaped alternating episodes of oxidation and sulfidization experienced by the others. Thermal metamorphism in the CM chondrites is apparent in loss of thermally labile trace elements and also in partial to almost complete dehydration of matrix phyllosilicates: heating was less uniform in them than in CI chondrites. This dehydration is also evident in strength and shapes of integrated intensities of the 3 μm bands except in PCA 91008, which experienced extensive terrestrial weathering. Tochilinite is absent in all but Y-793321 probably due to heating. Textural evidence for thermal metamorphism is conspicuous in blurring or integration/fusion of chondrules with matrix in the more extensively heated (⩾600 °C) CM chondrites like PCA 91008 and B-7904. TEM and XRD analyses reveal that phyllosilicate transformation to anhydrous phases proceeds via poorly crystalline, highly desiccated and disordered 'intermediate' phases in the least and moderately heated (400-600 °C) carbonaceous chondrites like WIS 91600, PCA 91008 and Y-86029. These findings are significant in that they confirm that these phases occur in meteorites as well as terrestrial samples. Thermal alteration in these meteorites can be used to identify other carbonaceous chondrites that were thermally

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

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  6. LIME silicates in amoeboid olivine aggregates in carbonaceous chondrites: Indicator of nebular and asteroidal processes

    NASA Astrophysics Data System (ADS)

    Komatsu, Mutsumi; Fagan, Timothy J.; Mikouchi, Takashi; Petaev, Michail I.; Zolensky, Michael E.

    2015-07-01

    MnO/FeO ratios in olivine from amoeboid olivine aggregates (AOAs) reflect conditions of nebular condensation and can be used in concert with matrix textures to compare metamorphic conditions in carbonaceous chondrites. LIME (low-iron, Mn-enriched) olivine was identified in AOAs from Y-81020 (CO3.05), Kaba (CV~3.1), and in Y-86009 (CV3), Y-86751 (CV3), NWA 1152 (CR/CV3), but was not identified in AOAs from Efremovka (CV3.1-3.4) or Allende (CV>3.6). According to thermodynamic models of nebular condensation, LIME olivine is stable at lower temperatures than Mn-poor olivine and at low oxygen fugacities (dust enrichment <10× solar). Although this set of samples does not represent a single metamorphic sequence, the higher subtypes tend to have AOA olivine with lower Mn/Fe, suggesting that Mn/Fe decreases during parent body metamorphism. Y-81020 has the lowest subtype and most forsteritic AOA olivine (Fo>95) in our study, whereas Efremovka AOAs are slightly Fe-rich (Fo>92). AOA olivines from Kaba are mostly forsteritic, but rare Fe-rich olivine precipitated from an aqueous fluid. A combination of precipitation of Fe-rich olivine and diffusion of Fe into primary olivine grains resulted in iron-rich compositions (Fo97-59) in Allende AOAs. Variations from fine-grained, nonporous matrix toward higher porosity and coarser lath-like matrix olivine can be divided into six stages represented by (1) Y-81020, Efremovka, NWA 1152; (2) Y-86751 lithology B; (3) Y-86009; (4) Kaba; (5) Y-86751 lithology A; (6) Allende. These stages are inferred to represent general degree of metamorphism, although the specific roles of thermally driven grain growth and diffusion versus aqueous dissolution and precipitation remain uncertain.

  7. Rhenium-osmium isotope systematics of carbonaceous chondrites

    USGS Publications Warehouse

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

    1989-01-01

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

  8. Mineralogy of Carbonaceous Chondrites and ACFER 217 from the Sahara

    NASA Astrophysics Data System (ADS)

    Geiger, T.; Bischoff, A.

    1992-07-01

    Among the approximately 400 meteorites recovered in the past three years in the Sahara at least 19 carbonaceous chondrites exist. Ten paired samples belong to the CR- chondrite Acfer 059/El Djouf 001 which has been recently described (Bischoff et al., 1992a). Three samples (Acfer 182, 207, 214) represent a unique (carbonaceous) chondrite (Bischoff et al., 1992b) that has similarities to ALH 85085 (e.g. Scott, 1988). Here, we describe six unpaired carbonaceous chondrites and Acfer 217, an unusual chondritic breccia. Three chondrites probably belong to the CV- chondrites (Acfer 082, 086, 272) and two to the CO- chondrites (Acfer 202, 243). Acfer 094 has trace element characteristics of a CM-chondrite, but has oxygen isotope ratios different from CM-chondrites (Bischoff et al., 1991). CV-chondrites: Based on the petrography and mineral chemistry Acfer 082 and 086 are typical CV3 chondrites. Large coarse-grained CAIs (especially in Acfer 082), fine- grained spinel-rich and large olivine-rich aggregates, chondrules and fragments are embedded in a fine-grained groundmass mainly consisting of small Fe-rich olivine laths. In Acfer 082 and Acfer 086 the average compositions of matrix olivine are Fa 55 and Fa 40, respectively. Acfer 082 is quite fresh concerning the degree of weathering, whereas Acfer 086 is severely weathered as indicated by the occurrence of abundant calcite filling fractures and pores between the olivine laths of the matrix. Acfer 272 has a mineral chemistry similar to Acfer 082, but is in texture, trace element chemistry (Spettel et al., 1992), and oxygen isotopes (Mayeda and Clayton, pers. communication) different to Acfer 082. Acfer 272 has a densely compacted matrix without individual euhedral to subhedral olivine laths. CO-chondrites: Acfer 202 and 243 consist of abundant porphyritic chondrules, CAIs, olivine-rich inclusions, and fragments embedded in abundant fine-grained matrix. The main component of the matrix is Fe-rich olivine. Matrix olivines

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  11. Evidence for Extended Aqueous Alteration in CR Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  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. Aqueous Alteration Mineralogy in CM Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Chokai, J.; Zolensky, M.; Le, L.; Nakamura, K.; Mikouchi, T.; Monkawa, A.; Koizumi, E.; Miyamoto, M.

    2004-01-01

    Iron-nickel sulfides are found in most or all solar system environments, and are probably the only minerals found in all extraterrestrial materials on hand. Despite the ubiquity, they have not received the attention they deserve. The most common Fe-Ni sulfides in chondrites are troilite (FeS), pyrrhotite (Fe1- XS) and pentlandite (Fe,Ni)9S8. Troilite is believed to have resulted from sulfidation of metal (Fe-Ni) grains in an H2Scontaining environment. Pyrrhotite is produced when friable troilite grains, which are exfoliated from the metal nucleus, are submitted to continued sulfidation [1]. Some asteroids are known to have experienced aqueous alteration, forming products including new generations of sulfides (pyrrhotite and pentlandite). Pentlandite in particular is known to form during such alteration [1]. However, experimental work by Lauretta has indicated that pentlandite may also have been formed during the initial sulfidation process [2], due to the faster diffusion rate of nickel into the forming sulfide, as compared to iron. Finally, there is considerable evidence [1,3&4] for a family of phases intermediate between pyrrhotite and pentlandite, following the trend of the high temperature monosulfide solid solution [5], something not encountered in terrestrial rocks.

  14. Water-extractable and exchangeable phosphate in Martian and carbonaceous chondrite meteorites and in planetary soil analogs

    NASA Astrophysics Data System (ADS)

    Mautner, Michael N.; Sinaj, Sokrat

    2002-09-01

    Aqueous extraction contributes to the formation and weathering of planetary materials and renders electrolytes such as phosphate available for biology. In this context, the solubility of phosphate is measured in planetary materials, represented by the Mars meteorites Nakhla, Dar al Gani 476 (DaG 476), Elephant Morraine 79001 (EETA 79001), and terrestrial analogs, and in the Murchison CM2 and Allende CV3 carbonaceous chondrites. The Mars meteorites contain high levels of phosphate that is readily extracted by water, up to 15 mg kg -1 in Nakhla and DaG 476 and 38 mg kg -1 in EETA 79001, while the terrestrial analogs and the carbonaceous chondrites contain 0.5 to 6 mg kg -1. Correspondingly, high phosphate concentrations of 4 to >28 mg L -1 are obtained in extracts of the Mars meteorites at high solid/solution ratios, exceeding the concentrations of 0.4 to 2.0 mg L -1 in the extracts of the terrestrial analogs. A wide range of planetary conditions, including N 2 and CO 2 atmospheres, solid/solution ratios of 0.01 to 1.0 kg L -1, extraction times of 1 to 21 d, and temperatures of 20 to 121°C affect the amounts of extractable phosphate by factors of only 2 to 5 in most materials. Phosphate-fixing capacity and exchangeable phosphate are assessed by the isotopic exchange kinetics (IEK) method, which quantifies the amount of P isotopically exchangeable within 1 min (E 1min) and between 1 min and 3 months (E 1min-3m) and the amount of P that cannot be exchanged within 3 months (E >3m). The IEK results show that the DaG 476 Mars meteorite and terrestrial analogs have low P-fixing capacities, while the carbonaceous chondrites have high P-fixing capacities. Aqueous processing under early planetary CO 2 atmospheres has large effects on the available phosphate. For example, the fraction of total P that is exchangeable in 3 months increases from 1.6 to 11%, 13 to 51.6%, and 43.9 to 90.4% in the DaG 476 Mars meteorite, Allende, and Murchison, respectively. The results show that

  15. Stable Isotope Fractionation of Cr in Carbonaceous and Ordinary Chondrites

    NASA Astrophysics Data System (ADS)

    Moynier, F.; Jacobsen, B.; Yin, Q.

    2006-12-01

    Difficulties with chemical separation and mass spectrometry combined with little expectation of isotopic fractionation at high temperature left the stable isotope geochemistry of Cr almost unknown [1]. The search for ^{53}Cr excess resulting from the decay of the radioactive nuclide ^{53}Mn (T1/2 = 3.5 My) was very successful but the small amount of data produced to date attests to the particularly difficult measurement by TIMS. This preliminary report describes evidence of mass-dependent fractionation of the stable Cr isotopes 50, 52, and 53 as measured by MC-ICPMS in meteorites relative to SRM 979 Cr standard. Cr was purified using cation-exchange chemistry. The yield is ~100 %. The samples were run on the Nu- Plasma HR of UC Davis in pseudo high-resolution mode. The absence of isotopic fractionation induced by the chemical purification has been double checked by 1) processing the standard through the column and 2) running the same sample several times through the columns. In both cases, we observe no difference in the measured isotopic ratio. The external reproducibility, estimated from 13 replicates of Bjurbole, is 50 ppm. The range of the fractionation per mass unit among 7 carbonaceous chondrites (CI, CM, CO, CV and CK) and 5 ordinary chondrites (H, L and LL) is 0.3 ‰. Individual chondrules from Chainpur and Bjurbole have a wider range (0.6 ‰). All the chondrites analyzed so far are isotopically lighter than the bulk silicate earth (δ ^{50/52}Cr=0, [1]). As for Zn [2], Cr isotopes seem to be heavier in ordinary chondrites (-0.23 ‰) than in carbonaceous chondrites (-0.35 ‰). Also as for Zn and Cu [2-3], Cr stable isotopes in carbonaceous chondrites are correlated with Δ 17O, suggesting a mixing between an isotopically heavy component and an isotopically light one. The correlation between mass-dependent fractionation of Cr and non-mass-dependent Δ 17O requires attention and adequate interpretation. References: [1] Johnson and Bullen, 2004, Review in

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  17. Microscale Distribution of Hydrogen Isotopes in Two Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Young, A. F.; Nittler, L. R.; Alexander, C. M. O'D

    2004-01-01

    Hydrogen isotopes are highly variable among primitive meteorites and interplanetary dust particles (IDPs) [1, 2]. In particular, many primitive objects exhibit D (and N-15) enrichments, relative to terrestrial values, thought to represent partial preservation of presolar material fractionated in molecular clouds. However, the diversity of D/H ratios among IDPs and chondrites indicates a complex history of processing in the solar nebula and on meteorite parent bodies. Deconvolving this record requires identification and characterization of the carriers of D enrichments in different objects. Isotopic imaging has proven to be a powerful method to quantitatively explore the distribution of D/H ratios on a one to several m scale in IDPs [2-4] and the CR chondrite Renazzo [5, 6]. In this study, we have used ion imaging to explore the microscale D/H distribution of two carbonaceous chondrites, Tagish Lake (unique) and Al Rais (CR2). Previous D/H measurements (on a tens of microns scale) of Tagish Lake matrix fragments by Messenger [7] and Engrand et al. [8] have found different results, most likely related to the analytical techniques used. Previous work has also shown a large range of D/H ratios in CR chondrites, including very large variations on a scale of a few microns [5, 6, 9].

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  20. Theoretical predictions of volatile bearing phases and volatile resources in some carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Ganguly, Jibamitra; Saxena, Surendra K.

    1989-01-01

    Results are presented from theoretical calculations to predict the modal abundances and compositions of the major mineral phases and the vapor phase that could develop in the bulk compositions of carbonaceous chondrites. The abundances and compositions are obtained as functions of temperature and pressure. The calculations are used to evaluate the volatile and mineralogical resource potential of C1 and C2 carbonaceous chondrites.

  1. The onset of metamorphism in ordinary and carbonaceous chondrites

    USGS Publications Warehouse

    Grossman, J.N.; Brearley, A.J.

    2005-01-01

    Ordinary and carbonaceous chondrites of the lowest petrologic types were surveyed by X-ray mapping techniques. A variety of metamorphic effects were noted and subjected to detailed analysis using electron microprobe, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and cathodoluminescence (CL) methods. The distribution of Cr in FeO-rich olivine systematically changes as metamorphism increases between type 3.0 and type 3.2. Igneous zoning patterns are replaced by complex ones and Cr-rich coatings develop on all grains. Cr distributions in olivine are controlled by the exsolution of a Cr-rich phase, probably chromite. Cr in olivine may have been partly present as tetrahedrally coordinated Cr3+. Separation of chromite is nearly complete by petrologic type 3.2. The abundance of chondrules showing an inhomogeneous distribution of alkalis in mesostasis also increases with petrologic type. TEM shows this to be the result of crystallization of albite. Residual glass compositions systematically change during metamorphism, becoming increasingly rich in K. Glass in type I chondrules also gains alkalis during metamorphism. Both types of chondrules were open to an exchange of alkalis with opaque matrix and other chondrules. The matrix in the least metamorphosed chondrites is rich in S and Na. The S is lost from the matrix at the earliest stages of metamorphism due to coalescence of minute grains. Progressive heating also results in the loss of sulfides from chondrule rims and increases sulfide abundances in coarse matrix assemblages as well as inside chondrules. Alkalis initially leave the matrix and enter chondrules during early metamorphism. Feldspar subsequently nucleates in the matrix and Na re-enters from chondrules. These metamorphic trends can be used to refine classification schemes for chondrites. Cr distributions in olivine are a highly effective tool for assigning petrologic types to the most primitive meteorites and can be used to

  2. The Ni, Fe and CO contents of metal phases in the Allende, Holbrook and Nuevo Mercurio chondrites

    NASA Astrophysics Data System (ADS)

    Miura, Y.; Smith, D. G. W.; Launspach, S.

    1983-12-01

    The Ni, Fe and Co contents of metal phases in the Allende, Holbrook and Nuevo Mercurio chondrites have been obtained using an automated electron microprobe fitted with both wavelength and energy dispersive spectrometers. Co contents of kamacite in these chondrites are inconsistent with those reported previously, but the general tendency of Co to increase in the kamacite in chondrites from H, L to LL groups, is supported by the study. Although the variation patterns of Ni-Co observed so far for L4, H5 and CV3 chondrites are simple, six L6 chondrites, including those reported previously, show significant difference in Co contents and the concentration and abundance charcateristics of Ni-Fe-Co patterns of the metal phases. The great similarity of composition of each region of these patterns obtained from two samples of Holbrook and two samples of Allende which came from different collections, indicate that the variation patterns of Ni-Co in the metal phases provide a means of characterizing or 'fingerprinting', as do the great differences in the variation patterns of Fe-Ni-Co which occur from one chondrite to another or even within the same group and petrologic type.

  3. Oxygen isotope heterogeneity in chondrules from the Mokoia CV3 carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Jones, Rhian H.; Leshin, Laurie A.; Guan, Yunbin; Sharp, Zachary D.; Durakiewicz, Tomasz; Schilk, Alan J.

    2004-08-01

    We report a study of the oxygen isotope ratios of chondrules and their constituent mineral grains from the Mokoia, oxidized CV3 chondrite. Bulk oxygen isotope ratios of 23 individual chondrules were determined by laser ablation fluorination, and oxygen isotope ratios of individual grains, mostly olivine, were obtained in situ on polished mounts using secondary ion mass spectrometry (SIMS). Our results can be compared with data obtained previously for the oxidized CV3 chondrite, Allende. Bulk oxygen isotope ratios of Mokoia chondrules form an array on an oxygen three-isotope plot that is subparallel to, and slightly displaced from, the CCAM (carbonaceous chondrite anhydrous minerals) line. The best-fit line for all CV3 chondrite chondrules has a slope of 0.99, and is displaced significantly (by δ 17O ˜ -2.5‰) from the Young and Russell slope-one line for unaltered calcium-aluminum-rich inclusion (CAI) minerals. Oxygen isotope ratios of many bulk CAIs also lie on the CV-chondrule line, which is the most relevant oxygen isotope array for most CV chondrite components. Bulk oxygen isotope ratios of most chondrules in Mokoia have δ 18O values around 0‰, and olivine grains in these chondrules have similar oxygen isotope ratios to their bulk values. In general, it appears that chondrule mesostases have higher δ 18O values than olivines in the same chondrules. Our bulk chondrule data spread to lower δ 18O values than any ferromagnesian chondrules that have been measured previously. Two chondrules with the lowest bulk δ 18O values (-7.5‰ and -11.7‰) contain olivine grains that display an extremely wide range of oxygen isotope ratios, down to δ 17O, δ 18O around -50‰ in one chondrule. In these chondrules, there are no apparent relict grains, and essentially no relationships between olivine compositions, which are homogeneous, and oxygen isotopic compositions of individual grains. Heterogeneity of oxygen isotope ratios within these chondrules may be the

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  5. Evaluation of the Strecker synthesis as a source of amino acids on carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Lerner, N. R.; Peterson, Etta; Chang, S.

    1991-01-01

    The Strecker synthesis (SS) has been proposed as the source of amino acids (AA) formed during aqueous alteration of carbonaceous chondrites. It is postulated that the aldehyde and ketone precursors of the meteoritic AA originated in interstellar syntheses and accreted on the meteorite parent body along with other reactant species in cometesimal ices. The SS has been run with formaldehyde, acetyldehyde, propionaldehyde, acetone, and methyl ketone as starting materials. To study the effect of minerals on the reaction, the SS was run in the presence and absence of dust from the Allende meteorite using deuterated aldehydes and ketones as starting materials. The products were studied by GC/MS. With the exception of glycine, the retention of deuterium in the AA was greater than 90 pct. Some D exchange with water does occur, however, and determination of the rate of exchange as a function of pH and temperature may allow some bounds to be placed on the duration of parent body aqueous alteration. The retention of D by the AA under conditions studied thus far is consistent with the model that a SS starting from interstellar aldehydes and ketones led to the production of meteoritic AA.

  6. UV to far-IR reflectance spectra of carbonaceous chondrites - I. Implications for remote characterization of dark primitive asteroids targeted by sample-return missions

    NASA Astrophysics Data System (ADS)

    Trigo-Rodríguez, Josep M.; Moyano-Cambero, Carles E.; Llorca, Jordi; Fornasier, Sonia; Barucci, Maria A.; Belskaya, Irina; Martins, Zita; Rivkin, Andy S.; Dotto, Elisabetta; Madiedo, José M.; Jacinto, Alonso-Azcárate

    2014-01-01

    We analyse here a wide sample of carbonaceous chondrites from historic falls (e.g. Allende, Cold Bokkeveld, Kainsaz, Leoville, Murchison, Murray, Orgueil and Tagish Lake) and from NASA Antarctic collection. With the analysis of these meteorites we want to get new clues on the role of aqueous alteration in promoting the reflectance spectra diversity evidenced in the most primitive chondrite groups. The selected meteorite specimens are a sample large enough to exemplify how laboratory reflectance spectra of rare groups of carbonaceous chondrites exhibit distinctive features that can be used to remotely characterize the spectra of primitive asteroids. Our spectra cover the full electromagnetic spectrum from 0.2 to 25 μm by using two spectrometers. First one is an ultraviolet (UV)-near-infrared (NIR) spectrometer that covers the 0.2-2 μm window, while the second one is an attenuated total reflectance infrared spectrometer covering the 2-25 μm window. In particular, laboratory analyses in the UV-NIR window allow obtaining absolute reflectance by using standardized measurement procedures. We obtained reflectance spectra of specimens belonging to the CI, CM, CV, CR, CO, CK, CH, R and CB groups of carbonaceous chondrites plus some ungrouped ones, and it allows identifying characteristic features and bands for each class, plus getting clues on the influence of parent body aqueous alteration. These laboratory spectra can be compared with the remote spectra of asteroids, but the effects of terrestrial alteration forming (oxy)hydroxides need to be considered.

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

    NASA Technical Reports Server (NTRS)

    2004-01-01

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

  8. Spectral evidence for a carbonaceous chondrite surface composition on Deimos

    NASA Technical Reports Server (NTRS)

    Pang, K. D.; Rhoads, J. W.; Lane, A. L.; Ajello, J. M.

    1980-01-01

    The surface compositions of Phobos and Deimos as determined by their UV-visible reflectance are compared in order to evaluate the hypothesis that the different surface morphologies of the two satellites are due to different mechanical properties. The UV-visible reflectance spectrum of Deimos is compiled from Mariner 9 UV spectrometry and Canopus star tracker photometry and ground-based colorimetry and polarimetry; the geometric albedo of Deimos is determined from Mariner 9 Canopus star tracker data. The reflectance spectra of Deimos and Phobos are found to be similar in a first approximation, exhibiting low, flat reflectivities in the visible and dropping off sharply in the UV, compatible with a probable carbonaceous chondrite nature for Deimos as well as Phobos and suggesting that their different surface morphologies are most likely due to different orbital histories.

  9. Exposure history of the Sutter's Mill carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Nishiizumi, K.; Caffee, M. W.; Hamajima, Y.; Reedy, R. C.; Welten, K. C.

    2014-11-01

    The Sutter's Mill (SM) carbonaceous chondrite fell in California on April 22, 2012. The cosmogenic radionuclide data indicate that Sutter's Mill was exposed to cosmic rays for 0.082 ± 0.008 Myr, which is one of the shortest ages for C chondrites, but overlaps with a small cluster at approximately 0.1 Myr. The age is significantly longer than proposed ages that were obtained from cosmogenic noble gas concentrations, which have large uncertainties due to trapped noble gas corrections. The presence of neutron-capture 60Co and 36Cl in SM indicates a minimum preatmospheric radius of approximately 50 cm, and is consistent with a radius of 1-2 m, as derived from the fireball observations. Although a large preatmospheric size was proposed, one fragment (SM18) contains solar cosmic ray-produced short-lived radionuclides, such as 56Co and 51Cr. This implies that this specimen was less than 2 cm from the preatmospheric surface of Sutter's Mill. Although this conclusion seems surprising, it is consistent with the observation that the meteoroid fragmented high in the atmosphere. The presence of SCR-produced nuclides is consistent with the high SCR fluxes observed during the last few months before the meteorite's fall, when its orbit was less than 1 AU from the Sun.

  10. An amoeboid olivine inclusion (AOI) in CK3 NWA 1559, comparison to AOIs in CV3 Allende, and the origin of AOIs in CK and CV chondrites

    NASA Astrophysics Data System (ADS)

    Rubin, Alan E.

    2013-03-01

    An amoeboid olivine inclusion in CK3 NWA 1559 (0.54 × 1.3 mm) consists of a diopside-rich interior (approximately 35 vol%) and an olivine-rich rim (approximately 65 vol%). It is the first AOI to be described in CK chondrites; the apparent paucity of these inclusions is due to extensive parent-body recrystallization. The AOI interior contains irregular 3-15 μm-sized Al-bearing diopside grains (approximately 70 vol%), 2-20 μm-sized pores (approximately 30 vol%), and traces of approximately 2 μm plagioclase grains. The 75-160 μm-thick rim contains 20-130 μm-sized ferroan olivine grains, some with 120º triple junctions. A few coarse (25-50 μm-sized) patches of plagioclase with 2-18 μm-thick diopside rinds occur in several places just beneath the rim. The occurrence of olivine rims around AOI-1 and around many AOIs in CV3 Allende suggests that CK and CV AOIs formed by the acquisition of porous forsteritic rims around fine-grained, rimless CAIs that consisted of diopside, anorthite, melilite, and spinel. Individual AOIs in carbonaceous chondrites may have formed after transient heating events melted their olivine rims as well as portions of the underlying interiors. In AOI-1, coarse plagioclase grains with diopside rinds crystallized immediately below the olivine rim. Secondary parent-body alteration transformed forsterite in the rims of CV and CK AOIs into more-ferroan olivine. Some of the abundant pores in the interior of AOI-1 may have formed during aqueous alteration after fine-grained melilite and anorthite were leached out. Chondrite groups with large chondrules tend to have large AOIs. AOIs that formed in dust-rich nebular regions (where CV and CK chondrites later accreted) tend to be larger than AOIs from less-dusty regions.

  11. Carbonaceous chondrites. II - Carbonaceous chondrite phyllosilicates and light element geochemistry as indicators of parent body processes and surface conditions

    NASA Technical Reports Server (NTRS)

    Bunch, T. E.; Chang, S.

    1980-01-01

    Petrographic analyses of CM matrices characterized four phyllosilicates in Murray and Murchison meteorites and Fe- and Mg-serpentines in Nogoya. All phyllosilicates and bulk matrices show enrichment of K relative to Na when compared with bulk meteorites; the loss of Na and some Cl, and the addition of H2O, CO2, and water-soluble organics during alteration indicates a partially open system. Synthesis of soluble organic materials may have occurred in CM matrices before aqueous alteration of the precursive phases. Nogoya was 95% altered and has a bulk C content of 5.2%, higher than any meteorite; also, it has the lowest measured C-13/C-12 ratio of any carbonaceous chondrite except for Karoonda.

  12. 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

    with the relatively calcic plagioclase are hallmarks of carbonaceous chondrite bulk compositions [2], but the oxygen isotopic compositions are quite unlike those of any known chondrite class. Bulk rock abundances by INAA relative to Allende analyzed simultaneously are 0.89 times for Fe and ~1.2 times for Cr, REE and Hf. We conclude that NWA 2788 is a unique metachondrite sampled from a new, perhaps now-disaggregated parent body accreted from a distinctive oxygen isotopic reservoir. It is possible that this body also may harbor or have harbored chondrule-bearing carbonaceous regolith materials ('CT chondrites') that are yet to be found or recognized. [1] Irving A. J. et al. (2005) 68th Met. Soc. Mtg., #5218; Bunch T. E. et al. (2005) LPS XXXVI, #2308 [2] Wasson J. T. and Kallemyn G. W. (1988) Phil. Trans. Roy. Soc. Lond. A325, 535-544.

  13. Hibonite, Ca2/Al, Ti/24O38, from the Leoville and Allende chondritic meteorites.

    NASA Technical Reports Server (NTRS)

    Keil, K.; Fuchs, L. H.

    1971-01-01

    Hibonite was discovered in light-colored, Ca-Al-Ti-rich and Si-Fe-poor, achondritic inclusions of the Leoville and Allende HL-group chondrites. Two varieties of hibonite occur: one emits a bright red-orange luminescence under electron bombardment and has high amounts of Al2O3 (87.7; 87.9) and low amounts of MgO (0.65; 0.8) and TiO2 (0.68; 0.8). The other emits a bright blue luminescence and is low in Al2O3 (78.7; 79.2) and high in MgO (3.3; 3.7) and TiO2 (6.5; 7.9) (in wt. %). The oxide CaO is about the same in both varieties. It is suggested that the change in the color of the visible luminescence results from changes in composition. The origin of hibonite which occurs in complex mineral assemblages together with anorthite, gelhenite, wollastonite, aluminous diopside, andradite, Ca-pyroxene, perovskite, spinel, taenite, chromite, and pentlandite, and in close proximity to nodules containing calcite, whewellite, forsterite and many of the aforementioned phases, is discussed. The proposition that hibonite and associated phases originated by contact metamorphism and metasomatism of calcite-dolomite bearing assemblages cannot, at this time, be completely ruled out.

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

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Tonui, E.; Zolensky, M. E.

    2001-01-01

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

  16. A neutron activation analysis of iridium concentration in Yamato carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Yabushita, S.; Wada, K.; Moriyama, H.; Takeuchi, K.

    1988-09-01

    Iridium concentration in extra-terrestrial bodies is an important quantity in relation to Ir-rich geological layers. Ir concentration of a Yamato carbonaceous chondrite (Y-793321) has been measured by a neutron activation method. The measurement yields a value (0.57±0.06) μg per gramme for the chondrite.

  17. Phyllosilicates in the Mokoia CV carbonaceous chondrite - Evidence for aqueous alteration in an oxidizing environment

    NASA Technical Reports Server (NTRS)

    Tomeoka, Kazushige; Buseck, Peter R.

    1990-01-01

    Most CV chondrites contain little if any phyllosilicate mineralization. A petrographic and transmission electron microscopy study of the Mokoia CV carbonaceous chondrite shows that the matrix, chondrules, aggregates, and inclusions all contain considerable amounts of phyllosilicates. The mineralogy and occurrence of phyllosilicates in Mokoia differ from those in the CI and CM chondrites. The differences suggests that aqueous alteration of the three meteorite groups probably occurred under a variety of conditions.

  18. Primordial Molecular Cloud Material in Metal-Rich Carbonaceous Chondrites

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.

    2016-03-01

    The menagerie of objects that make up our Solar System reflects the composition of the huge molecular cloud in which the Sun formed, a late addition of short-lived isotopes from an exploding supernova or stellar winds from a neighboring massive star, heating and/or alteration by water in growing planetesimals that modified and segregated the primordial components, and mixing throughout the Solar System. Outer Solar System objects, such as comets, have always been cold, hence minimizing the changes experienced by more processed objects. They are thought to preserve information about the molecular cloud. Elishevah Van Kooten (Natural History Museum of Denmark and the University of Copenhagen) and co-authors in Denmark and at the University of Hawai'i, measured the isotopic compositions of magnesium and chromium in metal-rich carbonaceous chondrites. They found that the meteorites preserve an isotopic signature of primordial molecular cloud materials, providing a potentially detailed record of the molecular cloud's composition and of materials that formed in the outer Solar System.

  19. An oxygen isotope study of Wark-Lovering rims on type A CAIs in primitive carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Bodénan, Jean-David; Starkey, Natalie A.; Russell, Sara S.; Wright, Ian P.; Franchi, Ian A.

    2014-09-01

    Calcium-aluminium-rich Inclusions (CAIs) and the thin Wark-Lovering (WL) rims of minerals surrounding them offer a record of the nature of changing conditions during the earliest stages of Solar System formation. Considerable heterogeneity in the gas composition in the immediate vicinity of the proto-Sun had previously been inferred from oxygen isotopic variations in the WL rim of a CAI from Allende (Simon et al., 2011). However, high precision and high spatial resolution oxygen isotope measurements presented in this study show that WL rim and pristine core minerals of individual CAIs from meteorites that had experienced only low degrees of alteration or low grade metamorphism (one from Léoville (reduced CV3), two in QUE 99177 (CR3.0) and two in ALHA 77307 (CO3.0)) are uniformly 16O-rich. This indicates that the previously observed variations are the result of secondary processes, most likely on the asteroid parent body, and that there were no temporal or spatial variations in oxygen isotopic composition during CAI and WL rim formation. Such homogeneity across three groups of carbonaceous chondrites lends further support for a common origin for the CAIs in all chondrites. 16O-poor oxygen reservoirs such as those associated with chondrule formation, were probably generated by UV photo-dissociation involving self-shielding mechanisms and must have occurred elsewhere in outer regions of the solar accretion disk.

  20. Young Pb-Isotopic Ages of Chondrules in CB Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Amelin, Yuri; Krot, Alexander N.

    2005-01-01

    CB (Bencubbin-type) carbonaceous chondrites differ in many ways from more familiar CV and CO carbonaceous chondrites and from ordinary chondrites. CB chondrites are very rich in Fe-Ni metal (50-70 vol%) and contain magnesian silicates mainly as angular to sub-rounded clasts (or chondrules) with barred olivine (BO) or cryptocrystalline (CC) textures. Both metal and silicates appear to have formed by condensation. The sizes of silicate clasts vary greatly between the two subgroups of CB chondrites: large (up to one cm) in CB(sub a) chondrites, and typically to much much less than 1 mm in CB(sub b) chondrites. The compositional and mineralogical differences between these subgroups and between the CB(sub s) and other types of chondrites suggest different environment and possibly different timing of chondrule formation. In order to constrain the timing of chondrule forming processes in CB(sub s) and understand genetic relationship between their subgroups, we have determined Pb-isotopic ages of silicate material from the CB(sub a) chondrite Gujba and CB(sub b) chondrite Hammadah al Hamra 237 (HH237 hereafter).

  1. Refractory Inclusion Size Distribution and Fabric Measured in a Large Slab of the Allende CV3 Chondrite

    NASA Technical Reports Server (NTRS)

    Srinivasan, P.; Simon, Justin I.; Cuzzi, J. N.

    2013-01-01

    Aggregate textures of chondrites reflect accretion of early-formed particles in the solar nebula. Explanations for the size and density variations of particle populations found among chondrites are debated. Differences could have risen out of formation in different locations in the nebula, and/or they could have been caused by a sorting process [1]. Many ideas on the cause of chondrule sorting have been proposed; some including sorting by mass [2,3], by X-winds [4], turbulent concentration [5], and by photophoresis [6]. However, few similar studies have been conducted for Ca-, Al-rich inclusions (CAIs). These particles are known to have formed early, and their distribution could attest to the early stages of Solar System (ESS) history. Unfortunately, CAIs are not as common in chondrites as chondrules are, reducing the usefulness of studies restricted to a few thin sections. Furthermore, the largest sizes of CAIs are generally much larger than chondrules, and therefore rarely present in most studied chondrite thin sections. This study attempts to perform a more representative sampling of the CAI population in the Allende chondrite by investigating a two decimeter-sized slab.

  2. Experimental shock metamorphism of the Murchison CM carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Tomeoka, Kazushige; Yamahana, Yasuhiro; Sekine, Toshimori

    1999-11-01

    A series of shock-recovery experiments were carried out on the Murchison CM carbonaceous chondrite by using a single-stage propellant gun. The Murchison samples were shocked in nine experiments at peak pressures from 4 to 49 GPa. The recovered samples were studied in detail by using an optical microscope, a scanning electron microscope and an electron-probe microanalyzer. Chondrules are flattened in the plane of the shock front at 4 to 30 GPa. The mean aspect ratio of chondrules increases from 1.17 to 1.57 roughly in proportion to the intensity of shock pressure up to ˜25 GPa. At 25 to 30 GPa, the mean aspect ratio does not increase further, and chondrules show increasingly more random orientations and degrade their preferred orientations, and at ˜35 GPa, they are extensively disrupted. Most coarse grains of olivine and pyroxene are irregularly fractured, fracture density increases with increasing shock pressure and at ˜30 GPa almost all are thoroughly fractured with subgrains of <1 to 5 μm in size. At ˜20 GPa, subparallel fractures begin to form in the matrix in directions roughly perpendicular to the compression axis and their densities increase with pressure, especially dramatically at 25 to 30 GPa; thus, the sample is increasingly comminuted and becomes fragile. Local shock melting occurs as melt veins and pockets at 20 to 30 GPa. Fracture-filling veins of fine grains of matrix are also produced at 25 to 30 GPa. The melts and the fine grains seem to result mainly from frictional heating due to displacement along fractures. At ˜35 GPa, melting occurs pervasively throughout the matrix. The melts are mainly produced from the matrix; however, they are consistently more enriched in Fe, S, and Ca, which indicates that these elements are selectively incorporated into the melts. The melts contain tiny spherules of Fe-Ni metal, Fe sulfide, and numerous vesicles. At 49 GPa, the matrix is totally melted and coarse grains of olivine are partially melted. The melts

  3. Oxygen isotopic composition of relict olivine grains in cosmic spherules: Links to chondrules from carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Rudraswami, N. G.; Prasad, M. Shyam; Nagashima, K.; Jones, R. H.

    2015-09-01

    Most olivine relict grains in cosmic spherules selected for the present study are pristine and have not been disturbed during their atmospheric entry, thereby preserving their chemical, mineralogical and isotopic compositions. In order to understand the origin of the particles, oxygen isotope compositions of relict olivine grains in twelve cosmic spherules collected from deep sea sediments of the Indian Ocean were studied using secondary ion mass spectrometry. Most of the data lie close to the CCAM (Carbonaceous Chondrite Anhydrous Mineral) line, with Δ17O ranging from -5‰ to 0‰. The data overlap oxygen isotopic compositions of chondrules from carbonaceous chondrites such as CV, CK, CR and CM, which suggests that chondrules from carbonaceous chondrites are the source of relict grains in cosmic spherules. Chemical compositions of olivine in cosmic spherules are also very similar to chondrule olivine from carbonaceous chondrites. Several olivine relict grains in three cosmic spherules are 16O-rich (Δ17O -21.9‰ to -18.7‰), similar to oxygen isotopic compositions observed in calcium aluminum rich inclusions (CAIs), amoeboid olivine aggregates (AOAs), and some porphyritic chondrules from carbonaceous chondrites. These grains appear to have recorded the initial oxygen isotopic composition of the inner solar nebula. Three olivine grains from two cosmic spherules have δ18O values >+20‰, which could be interpreted as mixing with stratospheric oxygen during atmospheric entry.

  4. A Re-Examination of Nucleobases in Carbonaceous Chondrites

    NASA Astrophysics Data System (ADS)

    Martins, Z.; Botta, O.; de Vries, M.; Becker, L.; Ehrenfreund, E.

    The biomolecular building blocks of life, as we know it, are amino acids, purines and pyrimidines. The latter two form the bases of DNA and RNA, molecules that are used in the storage, transcription and translation of genetic information in all terrestrial organisms. A dedicated search for these compounds in meteorites can shed light on the origins of life in two ways: (i) Results can help assess the plausibility of extraterrestrial formation of prebiotic molecules followed by their meteoritic delivery to the early Earth. (ii) Such studies can also provide insights into possible prebiotic synthetic routes. We will search for these compounds in selected carbonaceous chondrites using formic acid extraction and reverse phase high performance liquid chromatography (HPLC) to isolate specific nucleobases from the bulk meteorite material as previously reported [1,2,3]. We will also use a new technique, resonant two-photon ionization mass spectrometry (R2PI) that can, not only identify organic compounds by their mass, but at the same time by their vibronic spectroscopy [4]. R2PI dramatically enhances the specificity for certain compounds (e.g. amino acids, nucleobases) and allows for distinction of structural isomers, tautomers and enantiomers as well as providing additional information due to isotope shifts. The optical spectroscopy can thus help us to further discriminate between terrestrial and extraterrestrial nucleobases. References: [1] Van Der Velden, W. and Schwarts, A. W. (1977) Geochim. Cosmochim. Acta, 41, 961-968. [2] Stoks, P. G. and Schwartz, A. W. (1979a) Nature, 282, 709-10. [3] Glavin, D. P. and Bada, J. L. (2004) In Lunar and Planetary Science XXXV, Abstract # 1022, Houston. [4] Nir, E., Grace, L. I., Brauer, B. and de Vries, M. S. (1999) Journal of the American Chemical Society, 121, 4896-4897.

  5. Petrologic study of the Belgica 7904 carbonaceous chondrite - Hydrous alteration, oxygen isotopes, and relationship to CM and CI chondrites

    NASA Technical Reports Server (NTRS)

    Ikeda, Y.; Prinz, M.

    1993-01-01

    The genetic relationships between the petrology, hydration reactions, and isotopic oxygen composition in the Belgica 7904 (B7904) carbonaceous chondrite, and the relationship between B7904 and the CM and CI chondrites were investigated by characterizing seven components separated from B7904. The seven specimens included two partially altered chondrules, two phylosilicate clasts, two olivine fragments, and one matrix sample. The results of the analyses and thermodynamic calculations suggest that CI chondrites may have been produced in a two-stage alteration process from materials similar to that of the B7904 matrix, by reactions with liquid water in their parent body. The common CM chondrites may have undergone aqueous alteration in the parent body, in addition to hydration in the nebula, resulting in two-stage alterations; the parent body may have been different from that of B7904.

  6. Petrology and bulk chemistry of Yamato-82094, a new type of carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Kimura, M.; Barrat, J. A.; Weisberg, M. K.; Imae, N.; Yamaguchi, A.; Kojima, H.

    2014-03-01

    Carbonaceous chondrites are classified into several groups. However, some are ungrouped. We studied one such ungrouped chondrite, Y-82094, previously classified as a CO. In this chondrite, chondrules occupy 78 vol%, and the matrix is distinctly poor in abundance (11 vol%), compared with CO and other C chondrites. The average chondrule size is 0.33 mm, different from that in C chondrites. Although these features are similar to those in ordinary chondrites, Y-82094 contains 3 vol% Ca-Al-rich inclusions and 5% amoeboid olivine aggregates (AOAs). Also, the bulk composition resembles that of CO chondrites, except for the volatile elements, which are highly depleted. The oxygen isotopic composition of Y-82094 is within the range of CO and CV chondrites. Therefore, Y-82094 is an ungrouped C chondrite, not similar to any other C chondrite previously reported. Thin FeO-rich rims on AOA olivine and the mode of occurrence of Ni-rich metal in the chondrules indicate that Y-82094 is petrologic type 3.2. The extremely low abundance of type II chondrules and high abundance of Fe-Ni metal in the chondrules suggest reducing condition during chondrule formation. The depletion of volatile elements indicates that the components formed under high-temperature conditions, and accreted to the parent body of Y-82094. Our study suggests a wider range of formation conditions than currently recorded by the major C chondrite groups. Additionally, Y-82094 may represent a new, previously unsampled, asteroidal body.

  7. New Evidence for the Presence of Indigenous Microfossils in Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.; Rozanov, Alexei Yu.

    2004-01-01

    We present additional evidence for the presence of indigenous microfossils in carbonaceous meteorites scanning electron micrograph studies of freshly fractured interior surfaces of pristine samples of the Murchison CM2 carbonaceous meteorite have revealed forms in-situ that are recognizable as biofilms as well as complex and highly structured forms similar to calcareous and siliceous microfossils. Some of the forms encountered are very well-preserved and exhibit complex associated microstructures similar to bacterial flagella. New images will be presented of forms recently encountered in carbonaceous meteorites and they will be compared with those of known microbial extremophiles. KEYWORDS: carbonaceous chondrites, Murchison, microfossils, extremophiles

  8. 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

  9. 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  11. 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.

  12. 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

  13. Mineral chemistry and origin of spinel-rich inclusions in the Allende CV3 chondrite

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    The present electron probe microanalysis of 20 spinel-rich inclusions in Allende indicates that the mineralogy of spinel-rich Allende inclusions is similar to that of fine grained Ca, Al-rich inclusions (CAIs) in ALH-77003 and rims on coarse grained CAIs in Allende. The mineralogy, mineral chemistry, and bulk chemistry of the inclusions indicate that they are not primitive aggregates of crystalline nebular condensates, but rather aggregates of minute concentric objects that are presently interpreted to be a fractionated distillation residue that lost Ca, Si-rich partial melt. It is suggested that interstellar dust aggregates were melted or distilled into Allende inclusions by aerodynamic drag heating, in regions of the nebula where the dust/gas ratio was so enhanced that the local oxygen fugacity was raised by several order of magnitude and liquids became thermodynamically stable.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  15. The Oxygen Isotope Composition of Dark Inclusions in HEDs, Ordinary and Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Greenwood, R. C.; Zolensky, M. E.; Buchanan, P. C.; Franchi, I. A.

    2015-01-01

    Dark inclusions (DIs) are lithic fragments that form a volumetrically small, but important, component in carbonaceous chondrites. Carbonaceous clasts similar to DIs are also found in some ordinary chondrites and HEDs. DIs are of particular interest because they provide a record of nebular and planetary processes distinct from that of their host meteorite. DIs may be representative of the material that delivered water and other volatiles to early Earth as a late veneer. Here we focus on the oxygen isotopic composition of DIs in a variety of settings with the aim of understanding their formational history and relationship to the enclosing host meteorite.

  16. Petrologic Locations of Nanodiamonds in Carbonaceous Chondrite Meteorites

    NASA Astrophysics Data System (ADS)

    Garvie, Laurence

    Nanodiamonds (NDs), with dimensions near two nanometers, are widespread accessory minerals in primitive meteorites. They have been studied extensively in concentrates made from acid-insoluble residues, but surprisingly little is known about their petrologic settings in the meteorites because they have not been studied in situ. Information about such settings is fundamental for determining how they formed and were incorporated into the meteorites. The primary goal of the planned research is to determine and compare the petrologic settings of NDs within matrix of different types of carbonaceous chondrites, with the long-term aim of providing new insights regarding the origin of NDs. This research will also provide new data on the structure and major and trace element compositions of individual NDs and regions within them. Transmission electron microscopes (TEMs) provide uniquely powerful information regarding chemical, bonding, and structural data on the scale needed to solve this problem, assuming the NDs can be located within the host matrix. We have developed methods of observing NDs in situ within the fine-grained matrix of primitive meteorites and will use various TEMs to accomplish that goal for several meteorites. High- resolution imaging and electron energy-loss spectroscopy (EELS) will permit determination of both structural and chemical information about the NDs and their adjacent minerals. By the middle of the proposed grant period, two state-of-the-art, aberration-corrected TEMs will have been installed at ASU and will be used to locate heavy elements such as Xe, Te, and Pd within the NDs. These TEMs permit the imaging of individual atoms of heavy elements with annular dark-field (ADF) imaging, and these atoms can be identified using EELS. The result of these new types of measurements will provide information about whether such elements, which have been used to determine whether NDs formed in supernovae, occur within the interiors or on the surfaces of

  17. Theoretical predictions of volatile bearing phases and volatile resources in some carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Ganguly, Jibamitra; Saxena, Surendra K.

    1989-01-01

    Carbonaceous chondrites are usually believed to be the primary constituents of near-Earth asteroids and Phobos and Diemos, and are potential resources of fuels which may be exploited for future planetary missions. The nature and abundances are calculated of the major volatile bearing and other phases, including the vapor phase that should form in C1 and C2 type carbonaceous chondrites as functions of pressure and temperature. The results suggest that talc, antigorite plus or minus magnesite are the major volatile bearing phases and are stable below 400 C at 1 bar in these chondritic compositions. Simulated heating of a kilogram of C2 chondrite at fixed bulk composition between 400 and 800 C at 1 bar yields about 135 gm of volatile, which is made primarily of H2O, H2, CH4, CO2 and CO. The relative abundances of these volatile species change as functions of temperature, and on a molar basis, H2 becomes the most dominant species above 500 C. In contrast, Cl chondrites yield about 306 gm of volatile under the same condition, which consist almost completely of 60 wt percent H2O and 40 wt percent CO2. Preliminary kinetic considerations suggest that equilibrium dehydration of hydrous phyllosilicates should be attainable within a few hours at 600 C. These results provide the framework for further analyses of the volatile and economic resource potentials of carbonaceous chondrites.

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Black, D. C.

    1975-01-01

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

  20. Mineralogic and petrologic study of the low-temperature minerals in carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Wood, J. A.

    1977-01-01

    Samples and petrographic thin sections of the Orgueil, Ivuna, and Alais chondrites were examined by optical, X-ray, and SEM techniques. Mineral species identified as primary vein constituents were epsomite, gypsum, and a calcium-magnesium carbonate. Relative abundances and textural relationships have suggested that fracture mineralization was a multi stage process, with individual mineralizations closely associated with impact brecciation events. Mass balance considerations of carbonaceous chondrite matrix support the prevailing view that the source of the fracture filling minerals was local. By inference they also suggest that the phyllosilicate matrix has been chemically altered and that there are probably very few primitive mineral phases in the primitive Cl chondrites.

  1. Localized Chemical Redistribution During Aqueous Alteration in CR2 Carbonaceous Chondrites EET 87770 and EET 92105

    NASA Technical Reports Server (NTRS)

    Burger, Paul V.; Brearley, Adrian J.

    2005-01-01

    Carbonaceous chondrites are primitive meteorites that are valuable because they preserve evidence of processes that occurred in the solar nebula and on asteroidal parent bodies. Among the carbonaceous chondrite groups, the CR group appears to contain a particularly pristine record of early solar system processes. Distinguishing characteristics of CR2 chondrites include a high abundance of chondrules (50-60 vol.%) and Fe, Ni metal (5-8 vol. %). These meteorites preserve evidence for varying degrees of aqueous alteration, manifested by progressive replacement of chondrule mesostasis by phyllosilicates. Recent studies have suggested that even in weakly altered chondrites, mass transfer occurred between chondrules and fine-grained matrices, implying that aqueous alteration must have followed lithification of the final meteorite parent body. Although petrographic characteristics of alteration in CR chondrites have been documented, mechanisms of alteration are still only poorly understood. For example, the relative rates and scales of elemental mobility as well as the sources and sinks for key elements are currently not constrained. An improved knowledge of these issues will contribute to an increased understanding of aqueous alteration reactions on meteorite parent bodies. This study expands on research conducted on Type IIA chondrules and chondrule fragments from two CR2 chondrites, EET 87770 and EET 92105. These chondrites have been weakly altered; chondrule mesostases show incipient alteration primarily where they are in direct contact with fine-grained matrices.

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  3. 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.

  4. Origin of plagioclase-olivine inclusions in carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

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

    1991-02-01

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

  5. 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.

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

    PubMed

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

    1997-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  8. 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

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. Aqueous alteration on the parent bodies of carbonaceous chondrites: Computer simulations of late-stage oxidation

    NASA Technical Reports Server (NTRS)

    Bourcier, W. L.; Zolensky, Michael E.

    1991-01-01

    CI carbonaceous chondrites may be products of hydrous alteration of CV- or anhydrous CM-type materials. The CIs typically contain veins filled with carbonates and sulfates, probably indicating a period of late stage aqueous alteration under oxidizing conditions. To test this idea, computer simulations of aqueous alteration of CV- and CM-type carbonaceous were performed. Simulations were restricted to the oxidation of hydrous mineral assemblages produced in previous simulations in order to determine whether further reaction and oxidation results in the phyllosilicate, carbonate, sulfate and oxide vein assemblages typical of CI carbonaceous chondrites. Our simulations were performed at 1, 25, 100, and 150 C (the appropriate temperature range) for the CV and CM mineral assemblages and using the computer code EQ3/6.

  14. Matrix mineralogy of the Orgueil CI carbonaceous chondrite

    NASA Technical Reports Server (NTRS)

    Tomeoka, Kazushige; Buseck, Peter R.

    1988-01-01

    This paper presents the results of petrographic, SEM, and TEM studies of the matrix minerals in Orgueil. It was found that the matrix consists mainly of Fe-bearing Mg-rich serpentine and saponite, and a poorly crystallized Fe-rich ferrihydrite containing small and varying amounts of S and Ni. The serpentine and saponite, which occur in roughly equal molar proportions, are coherently intergrown and occur mainly in fine phyllosilicates in intimate association with the ferrihydrite. Coarse phylosilicates occur in clusters relatively free of ferrihydrite. The matrix mineralogy of the Orgueil chondrite suggests that Orgueil experienced considerably different alteration conditions than did the CM chondrites.

  15. 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

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

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Prasanta K.

    2011-10-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  18. CM Carbonaceous Chondrite Lithologies and Their Space Exposure Ages

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael; Gregory, Timothy; Takenouchi, Atsushi; Nishiizumi, Kunihiko; Trieman, Alan; Berger, Eve; Le, Loan; Fagan, Amy; Velbel, Michael; Imae, Naoya; Yamaguchi, Akira

    2015-01-01

    The CMs are the most commonly falling C chondrites, and therefore may be a major component of C-class asteroids, the targets of several current and future space missions. Previous work [1] has concluded that CM chondrites fall into at least four distinct cosmic ray space exposure (CRE) age groups (0.1 million years, 0.2 million years, 0.6 million years and greater than 2.0 million years), an unusually large number, but the meaning of these groupings is unclear. It is possible that these meteorites came from different parent bodies which broke up at different times, or instead came from the same parent body which underwent multiple break-up events, or a combination of these scenarios, or something else entirely. The objective of this study is to investigate the diversity of lithologies which make up CM chondrites, in order to determine whether the different exposure ages correspond to specific, different CM lithologies, which permit us to constrain the history of the CM parent body(ies). We have already reported significant petrographic differences among CM chondrites [2-4]. We report here our new results.

  19. Investigation of pyridine carboxylic acids in CM2 carbonaceous chondrites: Potential precursor molecules for ancient coenzymes

    NASA Astrophysics Data System (ADS)

    Smith, Karen E.; Callahan, Michael P.; Gerakines, Perry A.; Dworkin, Jason P.; House, Christopher H.

    2014-07-01

    The distribution and abundances of pyridine carboxylic acids (including nicotinic acid) in eight CM2 carbonaceous chondrites (ALH 85013, DOM 03183, DOM 08003, EET 96016, LAP 02333, LAP 02336, LEW 85311, and WIS 91600) were investigated by liquid chromatography coupled to UV detection and high resolution Orbitrap mass spectrometry. We find that pyridine monocarboxylic acids are prevalent in CM2-type chondrites and their abundance negatively correlates with the degree of pre-terrestrial aqueous alteration that the meteorite parent body experienced. We also report the first detection of pyridine dicarboxylic acids in carbonaceous chondrites. Additionally, we carried out laboratory studies of proton-irradiated pyridine in carbon dioxide-rich ices (a 1:1 mixture) to serve as a model of the interstellar ice chemistry that may have led to the synthesis of pyridine carboxylic acids. Analysis of the irradiated ice residue shows that a comparable suite of pyridine mono- and dicarboxylic acids was produced, although aqueous alteration may still play a role in the synthesis (and ultimate yield) of these compounds in carbonaceous meteorites. Nicotinic acid is a precursor to nicotinamide adenine dinucleotide, a likely ancient molecule used in cellular metabolism in all of life, and its common occurrence in CM2 chondrites may indicate that meteorites may have been a source of molecules for the emergence of more complex coenzymes on the early Earth.

  20. 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.

  1. 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.

  2. Investigation of Pyridine Carboxylic Acids in CM2 Carbonaceous Chondrites: Potential Precursor Molecules for Ancient Coenzymes

    NASA Technical Reports Server (NTRS)

    Smith, Karen E.; Callahan, Michael P.; Gerakines, Perry A.; Dworkin, Jason P.; House, Christopher H.

    2014-01-01

    The distribution and abundances of pyridine carboxylic acids (including nicotinic acid) in eight CM2 carbonaceous chondrites (ALH 85013, DOM 03183, DOM 08003, EET 96016, LAP 02333, LAP 02336, LEW 85311, and WIS 91600) were investigated by liquid chromatography coupled to UV detection and high resolution Orbitrap mass spectrometry. We find that pyridine monocarboxylic acids are prevalent in CM2-type chondrites and their abundance negatively correlates with the degree of pre-terrestrial aqueous alteration that the meteorite parent body experienced. We lso report the first detection of pyridine dicarboxylic acids in carbonaceous chondrites. Additionally, we carried out laboratory studies of proton-irradiated pyridine in carbon dioxide-rich ices (a 1:1 mixture) to serve as a model of the interstellar ice chemistry that may have led to the synthesis of pyridine carboxylic acids. Analysis of the irradiated ice residue shows that a comparable suite of pyridine mono- and dicarboxylic acids was produced, although aqueous alteration may still play a role in the synthesis (and ultimate yield) of these compounds in carbonaceous meteorites. Nicotinic acid is a precursor to nicotinamide adenine dinucleotide, a likely ancient molecule used in cellular metabolism in all of life, and its common occurrence in CM2 chondrites may indicate that meteorites may have been a source of molecules for the emergence of more complex coenzymes on the early Earth.

  3. Investigation of Pyridine Carboxylic Acids in CM2 Carbonaceous Chondrites: Potential Precursor Molecules for Ancient Coenzymes

    NASA Technical Reports Server (NTRS)

    Smith, Karen E.; Callahan, Michael P.; Gerakines, Perry A.; Dworkin, Jason P.; House, Christopher H.

    2014-01-01

    The distribution and abundances of pyridine carboxylic acids (including nicotinic acid) in eight CM2 carbonaceous chondrites (ALH 85013, DOM 03183, DOM 08003, EET 96016, LAP 02333, LAP 02336, LEW 85311, and WIS 91600) were investigated by liquid chromatography coupled to UV detection and high resolution Orbitrap mass spectrometry. We find that pyridine monocarboxylic acids are prevalent in CM2-type chondrites and their abundance negatively correlates with the degree of pre-terrestrial aqueous alteration that the meteorite parent body experienced. We also report the first detection of pyridine dicarboxylic acids in carbonaceous chondrites. Additionally, we carried out laboratory studies of proton-irradiated pyridine in carbon dioxide-rich ices (a 1:1 mixture) to serve as a model of the interstellar ice chemistry that may have led to the synthesis of pyridine carboxylic acids. Analysis of the irradiated ice residue shows that a comparable suite of pyridine mono- and dicarboxylic acids was produced, although aqueous alteration may still play a role in the synthesis (and ultimate yield) of these compounds in carbonaceous meteorites. Nicotinic acid is a precursor to nicotinamide adenine dinucleotide, a likely ancient molecule used in cellular metabolism in all of life, and its common occurrence in CM2 chondrites may indicate that meteorites may have been a source of molecules for the emergence of more complex coenzymes on the early Earth.

  4. A search for C[sub 60] in carbonaceous chondrites

    SciTech Connect

    Vries, M.S.; Reihs, K.; Wendt, H.R.; Golden, W.G.; Hunziker, H.E. ); Fleming, R. ); Peterson, E.; Chang, S. )

    1993-02-01

    Analysis of interior samples of the Murchison meteorite by two routes yielded an upper limit of 2 ppb for its C[sub 60] content, as compared to parts per million levels for individual polycyclic aromatic hydrocarbons (PAHs). Provided the samples contain an interstellar component, which is probable since Murchison hydrocarbons contain excess deuterium, this result argues against the ubiquitous presence of C[sub 60] in the interstellar medium. A possible explanation for the absence of C[sub 60] was found in experiments showing how PAHs replace fullerenes as stable end products when hydrogen is present during carbon condensation. As a secondary result we found high molecular weight PAHs in the Murchison and Allende meteorites. Coronene and its methyl derivatives are especially interesting since features in the coronene spectrum have been shown to match some of the unidentified interstellar infrared emission bands.

  5. A search for C60 in carbonaceous chondrites.

    PubMed

    De Vries, M S; Reihs, K; Wendt, H R; Golden, W G; Hunziker, H E; Fleming, R; Peterson, E; Chang, S

    1993-01-01

    Analysis of interior samples of the Murchison meteorite by two routes yielded an upper limit of 2 ppb for its C60 content, as compared to parts per million levels for individual polycyclic aromatic hydrocarbons (PAHs). Provided the samples contain an interstellar component, which is probable since Murchison hydrocarbons contain excess deuterium, this result argues against the ubiquitous presence of C60 in the interstellar medium. A possible explanation for the absence of C60 was found in experiments showing how PAHs replace fullerenes as stable end products when hydrogen is present during carbon condensation. As a secondary result we found high molecular weight PAHs in the Murchison and Allende meteorites. Coronene and its methyl derivatives are especially interesting since features in the coronene spectrum have been shown to match some of the unidentified interstellar infrared emission bands.

  6. A search for C60 in carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    De Vries, M. S.; Reihs, K.; Wendt, H. R.; Golden, W. G.; Hunziker, H. E.; Fleming, R.; Peterson, E.; Chang, S.

    1993-01-01

    Analysis of interior samples of the Murchison meteorite by two routes yielded an upper limit of 2 ppb for its C60 content, as compared to parts per million levels for individual polycyclic aromatic hydrocarbons (PAHs ). Provided the samples contain an interstellar component, which is probable since Murchison hydrocarbons contain excess deuterium, this result argues against the ubiquitous presence of C60 in the interstellar medium. A possible explanation for the absence of C60 was found in experiments showing how PAHs replace fullerenes as stable end products when hydrogen is present during carbon condensation. As a secondary result we found high molecular weight PAHs in the Murchison and Allende meteorites. Coronene and its methyl derivatives are especially interesting since features in the coronene spectrum have been shown to match some of the unidentified interstellar infrared emission bands.

  7. A plausible link between the asteroid 21 Lutetia and CH carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Moyano-Cambero, Carles E.; Trigo-Rodriguez, Josep M.; Llorca, Jordi; Fornasier, Sonia; Barucci, Maria A.; Rimola, Albert

    2016-08-01

    A crucial topic in planetology research is establishing links between primitive meteorites and their parent asteroids. In this study, we investigate the feasibility of a connection between asteroids similar to 21 Lutetia, encountered by the Rosetta mission in July 2010, and the CH3 carbonaceous chondrite Pecora Escarpment 91467 (PCA 91467). Several spectra of this meteorite were acquired in the ultraviolet to near-infrared (0.3-2.2 μm) and in the midinfrared to thermal infrared (2.5-30.0 μm or 4000 to ~333 cm-1), and they are compared here to spectra from the asteroid 21 Lutetia. There are several similarities in absorption bands and overall spectral behavior between this CH3 meteorite and 21 Lutetia. Considering also that the bulk density of Lutetia is similar to that of CH chondrites, we suggest that this asteroid could be similar, or related to, the parent body of these meteorites, if not the parent body itself. However, the apparent surface diversity of Lutetia pointed out in previous studies indicates that it could simultaneously be related to other types of chondrites. Future discovery of additional unweathered CH chondrites could provide deeper insight in the possible connection between this family of metal-rich carbonaceous chondrites and 21 Lutetia or other featureless, possibly hydrated high-albedo asteroids.

  8. Chemical compositions and classifica tion of five thermally altered carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Noronha, Bianca A.; Friedrich, Jon M.

    2014-08-01

    To establish the chemical group provenance of the five thermally altered carbonaceous chondrites Asuka (A-) 881551, Asuka-882113, Elephant Moraine (EET) 96026, Mulga (west), and Northwest Africa (NWA) 3133, we quantified 44 trace elements in each of them. We also analyzed Larkman Nunatak (LAR) 04318 (CK4), Miller Range (MIL) 090001 (CR2), Roberts Massif (RBT) 03522 (CK5) as reference samples as their chemical group affinity is already recognized. We conclude that Asuka-881551, Asuka-882113, and Mulga (west) are thermally metamorphosed CK chondrites. Compositionally, Elephant Moraine 96026 most resembles the CV chondrites. NWA 3133 is the most significantly thermally altered carbonaceous chondrite in our suite of samples. It is completely recrystallized (no chondrules or matrix remain), but its bulk composition is consistent with a CV-CK clan provenance. The thermally labile element (e.g., Se, Te, Zn, and Bi) depletion in NWA 3133 indicates a chemically open system during the heating episode. It remains unclear if the heat necessary for its thermal alteration of NWA 3133 was due to the decay of 26Al or was impact related. Finally, we infer that MIL 090001, Mulga (west), and NWA 3133 show occasional compositional signatures indicative of terrestrial alteration. The alteration is especially evident within the elements Sr, Ba, La, Ce, Th, U, and possibly Sb. Despite the alteration, we can still confidently place each of the altered chondrites within an established chemical group or clan.

  9. Carbonaceous chondrites: Early irradiation and Pu-244 fission records

    NASA Technical Reports Server (NTRS)

    Macdougall, J. D.

    1983-01-01

    The carbonaceous meteorites were studied. The studies which were conducted have evolved from investigations of early irradiation to mineralogic and petrologic studies of refractory inclusions and to an examination of the time scales of alteration processes on the parent bodies. The attached listing of papers and abstracts provide the details.

  10. Formation of P-Rich Olivine in DaG 978 Carbonaceous Chondrite Through Fluid-Assisted Metamorphism

    NASA Astrophysics Data System (ADS)

    Zhang, A. C.; Li, Y.; Chen, J. N.; Gu, L. X.; Wang, R. C.

    2016-08-01

    We describe an occurrence of P-rich olivine in the DaG 978 carbonaceous chondrite. Different from other natural P-rich olivine, the P-rich olivine should have formed through fluid-assisted metamorphism.

  11. Laboratory experiments on the weathering of iron meteorites and carbonaceous chondrites by iron-oxidizing bacteria

    NASA Astrophysics Data System (ADS)

    Gronstal, A.; Pearson, V.; Kappler, A.; Dooris, C.; Anand, M.; Poitrasson, F.; Kee, T. P.; Cockell, C. S.

    2009-03-01

    Batch culture experiments were performed to investigate the weathering of meteoritic material by iron-oxidizing bacteria. The aerobic, acidophilic iron oxidizer (A. ferrooxidans) was capable of oxidizing iron from both carbonaceous chondrites (Murchison and Cold Bokkeveld) and iron meteorites (York and Casas Grandes). Preliminary iron isotope results clearly show contrasted iron pathways during oxidation with and without bacteria suggesting that a biological role in meteorite weathering could be distinguished isotopically. Anaerobic iron-oxidizers growing under pH-neutral conditions oxidized iron from iron meteorites. These results show that rapid biologicallymediated alteration of extraterrestrial materials can occur in both aerobic and anaerobic environments. These results also demonstrate that iron can act as a source of energy for microorganisms from both iron and carbonaceous chondrites in aerobic and anaerobic conditions with implications for life on the early Earth and the possible use of microorganisms to extract minerals from asteroidal material.

  12. Comparison of the trace element composition of Tagish Lake with other primitive carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Friedrich, Jon M.; Wang, Ming-Sheng; Lipschutz, Michael E.

    2002-05-01

    A meteorite fall on 18 January 2000 was detected by U.S. Defense Department satellites which established its pre-impact orbit. Fresh samples were collected from frozen Tagish Lake in British Columbia a week later and some properties of these samples reveal it to be a unique meteorite. We characterized Tagish Lake and 8 other samples using ICPMS and RNAA: data for 47 elements reveal that each of 9 carbonaceous chondrites of different type exhibit the Orgueil-normalized plateaus expected for members of such types. Trends evident in Tagish Lake differ from all other carbonaceous chondrites, including CI and CM. Samples of Tagish Lake collected later show similar patterns affected by weathering.

  13. Ion Irradiation Experiments on the Murchison CM2 Carbonaceous Chondrite: Simulating Space Weathering of Primitive Asteroids

    NASA Technical Reports Server (NTRS)

    Keller, L. P.; Christoffersen, R.; Dukes, C. A.; Baragiola, R. A.; Rahman, Z.

    2015-01-01

    Remote sensing observations show that space weathering processes affect all airless bodies in the Solar System to some degree. Sample analyses and lab experiments provide insights into the chemical, spectroscopic and mineralogic effects of space weathering and aid in the interpretation of remote- sensing data. For example, analyses of particles returned from the S-type asteroid Itokawa by the Hayabusa mission revealed that space-weathering on that body was dominated by interactions with the solar wind acting on LL ordinary chondrite-like materials [1, 2]. Understanding and predicting how the surface regoliths of primitive carbonaceous asteroids respond to space weathering processes is important for future sample return missions (Hayabusa 2 and OSIRIS-REx) that are targeting objects of this type. Here, we report the results of our preliminary ion irradiation experiments on a hydrated carbonaceous chondrite with emphasis on microstructural and infrared spectral changes.

  14. Experimental test of the superheavy fission hypothesis in acid residues from the allende meteorite

    SciTech Connect

    Flynn, G.J.

    1982-01-01

    A description of a series of experiments to find evidence to confirm or contradict the hypothesis that isotopically anomalous Xe (called CCF-Xe) in carbonaceous chondrite meteorites results from the fission decay of a superheavy element is given. The first two experiments were searches for fossil evidence - fission tracks and isotopic anomalies - of superheavy fission decay in the Allende carbonaceous chondrite. It was demonstrated that chromite, a mineral rich in CCF-Xe, records fission tracks, and a search for such tracks in Allende chromite was performed with negative results. It was also demonstrated in certain CCF-XE rich phases of Allende, isotopic anomalies like those seen in Xe should be detectable in Ba and the light rare earths. Preliminary results from a collaborative measurement (with the University of Paris) show the Ba isotopic ratios to be normal in a CCF-Xe rich Allende sample. The third experiment was motivated by reports of the detection of a live, fissioning superheavy element, using a neutron counting technique, in bulk Allende (Flerov, 1978). Since almost all of the allegedly fissiogenic Xe in Allende is concentrated in certain acid insoluble phases, we developed a technique to detect low-level fission activity in these phases. Allende acid insoluble residue (provided by the University of Chicago) was dispersed in a 1 mg/cm/sup 2/ layer, between two track recording detectors. An automatic track locating system was developed to allow large detector areas to be scanned for rate fission events.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  16. Magnesium isotopes constraints on the origin of Mg-rich olivines from the Allende chondrite: Nebular versus planetary?

    NASA Astrophysics Data System (ADS)

    Villeneuve, Johan; Chaussidon, Marc; Libourel, Guy

    2011-01-01

    High precision Mg isotope measurements by multi-collector ion microprobe show that refractory olivines from the Allende chondrite, either olivines isolated in the matrix (2 samples studied) or olivines in type I chondrules (6 samples studied), have variable δ26Mg* enrichments and deficits (calculated in permil as the 26Mg deviation from the instrumental mass fractionation line) relative to the Earth. Most average δ26Mg* (noted δ26Mg*av) values (between 10 and 20 analyses per chondrule) are negative but the total range is from -0.029 (± 0.010) ‰ (2 sigma errors) to + 0.011 (± 0.011) ‰ with an exception of one olivine at + 0.043 (± 0.023) ‰. These variations in δ26Mg*av reflect the formation of the olivines from reservoirs enriched in various amounts of 26Mg by the decay of short-lived 26Al (T1/2 = 0.73 Ma). Similarly, 30 analyses of olivines from the Eagle Station pallasite show a δ26Mg*av value of -0.033 ± 0.008‰, as negative as some olivines from Allende chondrules and the Solar system initial δ26Mg* value of -0.038 ± 0.004‰ (defined at the time of formation of type B Ca-Al-rich inclusions - CAIs - when 26Al/27Al = 5.23 × 10-5, Jacobsen et al., 2008). Because olivines are Al-poor and because their Mg isotopic compositions are not reset during the chondrule forming events, their δ26Mg*av can be used to calculate model crystallization ages relative to various theoretical Mg isotope growth curves. The two end-member scenarios considered are (i) a “nebular” growth in which the Al/Mg ratio remains chondritic and (ii) a “planetary” growth in which a significant increase of the Al/Mg ratio can be due to, for instance, olivine magmatic fractionation. The low δ26Mg*av value of olivines from the Eagle Station pallasite demonstrate that metal-silicate differentiation occurred as early as ~ 0. 15- 0. 23+ 0. 29 Ma after CAIs in either of the growth scenarios. Similarly the variable δ26Mg*av values of refractory olivines can be understood if

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  18. ALH85085: a unique volatile-poor carbonaceous chondrite with possible implications for nebular fractionation processes

    USGS Publications Warehouse

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

    1988-01-01

    Allan Hills 85085 is a unique chondrite with affinities to the Al Rais-Renazzo clan of carbonaceous chondrites. Its constituents are less than 50 ??m in mean size. Chondrules and microchondrules of all textures are present; nonporphyritic chondrules are unusually abundant. The mean compositions of porphyritic, nonporphyritic and barred olivine chondrules resemble those in ordinary chondrites except that they are depleted in volatile elements. Ca-, Al-rich inclusions are abundant and largely free of nebular alteration; they comprise types similar to those in CM and CO chondrites, as well as unique types. Calcium dialuminate occurs in several inclusions. Metal, silicate and sulfide compositions are close to those in CM-CO chondrites and Al Rais and Renazzo. C1-chondrite clasts and metal-rich "reduced" clasts are present, but opaque matrix is absent. Siderophile abundances in ALH85085 are extremely high (e.g., Fe Si = 1.7 ?? solar), and volatiles are depleted (e.g., Na Si = 0.25 ?? solar, S Si = 0.03 ?? solar). Nonvolatile lithophile abundances are similar to those in Al Rais, Renazzo, and CM and CO chondrites. ALH85085 agglomerated when temperatures in the nebula were near 1000 K, in the same region where Renazzo, Al Rais and the CI chondrites formed. Agglomeration of high-temperature material may thus be a mechanism by which the fractionation of refractory lithophiles occurred in the nebula. Chondrule formation must have occurred at high temperatures when clumps of precursors were small. After agglomeration, ALH85085 was annealed and lightly shocked. C1 and other clasts were subsequently incorporated during late-stage brecciation. ?? 1988.

  19. Barium isotopes in Allende meteorite: evidence against an extinct superheavy element

    SciTech Connect

    Lewis, R.S.; Anders, E.; Shimamura, T.; Lugmair, G.W.

    1983-12-02

    Carbon and chromite fractions from the Allende meteorite that contain isotopically anomalous xenon-131 to xenon-136 (carbonaceous chondrite fission or CCF xenon) at up to 5 x 10/sup 11/ atoms per gram show no detectable isotopic anomalies in barium-130 to barium-138. This rules out the possibility that the CCF xenon was formed by in situ fission of an extinct superheavy element. Apparently the CCF xenon and its carbonaceous carrier are relics from stellar nucleosynthesis.

  20. Barium isotopes in allende meteorite: evidence against an extinct superheavy element.

    PubMed

    Lewis, R S; Anders, E; Shimamura, T; Lugmair, G W

    1983-12-01

    Carbon and chromite fractions from the Allende meteorite that contain isotopically anomalous xenon-131 to xenon-136 (carbonaceous chondrite fission or CCF xenon) at up to 5 x 10(11) atoms per gram show no detectable isotopic anomalies in barium-130 to barium-138. This rules out the possibility that the CCF xenon was formed by in situ fission of an extinct superheavy element. Apparently the CCF xenon and its carbonaceous carrier are relics from stellar nucleosynthesis.

  1. Barium isotopes in Allende meteorite - Evidence against an extinct superheavy element

    NASA Technical Reports Server (NTRS)

    Lewis, R. S.; Anders, E.; Shimamura, T.; Lugmair, G. W.

    1983-01-01

    Carbon and chromite fractions from the Allende meteorite that contain isotopically anomalous xenon-131 to xenon-136 (carbonaceous chondrite fission or CCF xenon) at up to 5 x 10 to the 11th atoms per gram show no detectable isotopic anomalies in barium-130 to barium-138. This rules out the possibility that the CCF xenon was formed by in situ fission of an extinct superheavy element. Apparently the CCF xenon and its carbonaceous carrier are relics from stellar nucleosynthesis.

  2. Thermally Mobile Trace Elements in Carbonaceous Chondrites From Cold and Hot Deserts

    NASA Astrophysics Data System (ADS)

    Lipschutz, M. E.

    2000-01-01

    Some decades ago, Anders and co-workers used RNAA to classify a number of trace elements as being volatile during nebular condensation and accretion into primitive objects based upon their strong depletion in (equilibrated) ordinary chondrites relative to C1 chondrites. Such elements, e.g. Ag, Bi, Cd, Cs, In, Se, Te, Tl, Zn and others, exhibit nearly constant, C1-normalized atomic abundances in C2 (CM2) and in C3 chondrites. They interpreted the near-constancy of these abundances according to a 2-component model in which volatiles were introduced into carbonaceous (and other) chondrites as C1 material which was diluted with differing proportions of high-temperature (i.e. volatile-free) components. In this view, mean volatile element abundances of 0.48 in C2 and 0.24-0.29 x C1 in C3 chondrites indicated that C2 and C3 chondrites are, respectively, about 1:1 and 1:2-3 mixtures of C1-like and high temperature materials. More recently, Xiao and Lipschutz found that C-normalized abundances of such volatile elements are nearly constant in most C2-6 chondrites (i.e. 25 non-Antarctic meteorites, nearly all falls, and 36 Antarctic finds) consistent with a 2-component mixing model. However, rather than being quantized, mean volatile element contents in each chondrite define a continuum from 0.92-0.14 x C1 for these 61 chondrites. A few carbonaceous chondrites, the first having been the NIPR consortium samples B-7904, Y-82162 and Y-86720, show an altered pattern: many of the volatile elements in each exhibit the usual constancy of C1-normalized atomic abundances, but modified by further depletion of Cd and other elements like Tl and Bi. These are the most mobile trace elements, i.e. those most readily vaporized and lost from primitive meteorites during week-long heating at greater than or equal to 400 C under low ambient pressures (initially 10-5 atm H2), simulating metamorphic conditions in a primitive parent body. Similarities between mobile element data for B-7904, Y-82162

  3. What Are Space Exposure Histories Telling Us about CM Carbonaceous Chondrites?

    NASA Technical Reports Server (NTRS)

    Takenouchi, A.; Zolensky, Michael E.; Nishiizumi, K.; Caffee, M.; Velbel, M. A.; Ross, K.; Zolensky, P.; Le, L.; Imae, N.; Yamaguchi, A.; Mikouchi, T.

    2013-01-01

    Chondrites are chemically primitive and carbonaceous (C) chondrites are potentially the most primitive among them because they mostly escaped thermal metamor-phism that affected the other chondrite groups and ratios of their major, non-volatile and most of the volatile elements are similar to those of the Sun. Therefore, C chondrites are ex-pected to retain a good record of the origin and early history of the solar system. Carbonaceous chondrites are chemically differentiated from other chondrites by their high Mg/Si ratios and refractory elements, and have experienced various degrees of aqueous alteration. They are subdivided into eight subgroups (CI, CM, CO, CV, CK, CR, CB and CH) based on major element and oxygen isotopic ratios. Their elemental ratios spread over a wide range though those of ordinary and enstatite chondrites are relatively uniform. It is critical to know how many sepa-rate bodies are represented by the C chondrites. In this study, CM chondrites, the most abundant carbona-ceous chondrites, are examined. They are water-rich, chon-drule- and CAI-bearing meteorites and most of them are brec-cias. High-temperature components such as chondrules, iso-lated olivine and CAIs in CMs are frequently altered and some of them are replaced by clay minerals and surrounded by sul-fides whose Fe was derived from mafic silicates. On the basis of degrees of aqueous alteration, CMs have been classified into subtypes from 1 to 2, although Rubin et al. [1] assigned subtype 1 to subtype 2 and subtype 2 to subtype 2.6 using various petrologic properties. The classification is based on petrographic and mineralogic properties. For example, though tochilinite (2[(Fe, Mg, Cu, Ni[])S] 1.57-1.85 [(Mg, Fe, Ni, Al, Ca)(HH)2]) clumps are produced during aqueous alteration, they disappear and sulfide appears with increasing degrees of aqueous alteration. Cosmic-ray exposure (CRE) age measurements of CM chondrites reveal an unusual feature. Though CRE ages of other chondrite

  4. Thermally Mobile Trace Elements in Carbonaceous Chondrites From Cold and Hot Deserts

    NASA Technical Reports Server (NTRS)

    Lipschutz, M. E.

    2000-01-01

    Some decades ago, Anders and co-workers used RNAA to classify a number of trace elements as being volatile during nebular condensation and accretion into primitive objects based upon their strong depletion in (equilibrated) ordinary chondrites relative to C1 chondrites. Such elements, e.g. Ag, Bi, Cd, Cs, In, Se, Te, Tl, Zn and others, exhibit nearly constant, C1-normalized atomic abundances in C2 (CM2) and in C3 chondrites. They interpreted the near-constancy of these abundances according to a 2-component model in which volatiles were introduced into carbonaceous (and other) chondrites as C1 material which was diluted with differing proportions of high-temperature (i.e. volatile-free) components. In this view, mean volatile element abundances of 0.48 in C2 and 0.24-0.29 x C1 in C3 chondrites indicated that C2 and C3 chondrites are, respectively, about 1:1 and 1:2-3 mixtures of C1-like and high temperature materials. More recently, Xiao and Lipschutz found that C-normalized abundances of such volatile elements are nearly constant in most C2-6 chondrites (i.e. 25 non-Antarctic meteorites, nearly all falls, and 36 Antarctic finds) consistent with a 2-component mixing model. However, rather than being quantized, mean volatile element contents in each chondrite define a continuum from 0.92-0.14 x C1 for these 61 chondrites. A few carbonaceous chondrites, the first having been the NIPR consortium samples B-7904, Y-82162 and Y-86720, show an altered pattern: many of the volatile elements in each exhibit the usual constancy of C1-normalized atomic abundances, but modified by further depletion of Cd and other elements like Tl and Bi. These are the most mobile trace elements, i.e. those most readily vaporized and lost from primitive meteorites during week-long heating at greater than or equal to 400 C under low ambient pressures (initially 10(exp -5) atm H2), simulating metamorphic conditions in a primitive parent body. Similarities between mobile element data for B-7904, Y

  5. Evidence for aqueous alteration in a carbonaceous xenolith from the Plainview /H5/ chondrite

    NASA Astrophysics Data System (ADS)

    Nozette, S.; Wilkening, L. L.

    1982-04-01

    The compositions of the mineral components of two inclusions within a CM-like clast in the Plainview (H5) chondrite are determined. The inclusions have the morphologies of an Allende-like, coarse-grained CAI and an amoeboid olivine inclusion, respectively. Major constituents of the altered inclusions are found to be calcite, Mg-Fe-rich phyllosilicates, Fe-Ti oxides, and an Al-rich phyllosilicate, and it is suggested that the alteration process would have required transport of Ne, Cl, H2O, CO2, and FeO. Liquid water appears to be the medium in which the alterations took place, due to the presence of hydrous phases and significant quantities of iron required to produce the mineral assemblages now present from the inferred starting materials.

  6. Thermally Mobile Trace Elements in Carbonaceous Chondrites from Cold and Hot Deserts

    NASA Technical Reports Server (NTRS)

    Lipschutz, M. E.

    1999-01-01

    Some decades ago, Anders and co-workers used RNAA to classify a number of trace elements as being volatile during nebular condensation and accretion into primitive objects based upon their strong depletion in (equilibrated) ordinary chondrites relative to C1 chondrites. Such elements, e.g. Ag, Bi, Cd, Cs, In, Se, Te, Tl, Zn and others, exhibit nearly constant, C1-normalized atomic abundances in C2 (CM2) and in C3 chondrites. They interpreted the near-constancy of these abundances according to a 2-component model in which volatiles were introduced into carbonaceous (and other) chondrites as Cl material which was diluted with differing proportions of high-temperature (i.e. volatile-free) components. In this view, mean volatile element abundances of 0.48 in C2 and 0.24-0.29 x C1 in C3 chondrites indicated that C2 and C3 chondrites are, respectively, about 1:1 and 1:2-3 mixtures of Cl-like and high temperature materials. More recently, C1 normalized abundances of such volatile elements are nearly constant in most C2-6 chondrites (i.e. 25 non-Antarctic meteorites, nearly all falls, and 36 Antarctic finds) consistent with a 2- component mixing model. However, rather than being quantized, mean volatile element contents in each chondrite define a continuum from 0.92-0.14 x Cl for these 61 chondrites. A few carbonaceous chondrites - the first having been the NIPR consortium samples B-7904, Y-82162 and Y-86720 - show an altered pattern: many of the volatile elements in each exhibit the usual constancy of C1-normalized atomic abundances, but modified by further depletion of Cd and other elements like Tl and Bi. These are the most mobile trace elements, i.e. those most readily vaporized and lost from primitive meteorites during week-long heating at greater than or equal to 400 C under low ambient pressures (initially 10 (exp -5) atm H2), simulating metamorphic conditions in a primitive parent body. Similarities between mobile element data for B-7904, Y-82162 and Y-86720 with

  7. 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.

  8. Structure of high-molecular carbonaceous compound in carbonaceous chondrites and formation of IR-spectroscopically similar compounds in the laboratory.

    PubMed

    Murae, T

    1997-01-01

    Main components of carbonaceous matter in carbonaceous chondrites are high molecular organic matter. Examinations of the compounds using pyrolysis GC/MS and FT-IR indicated the structural resemblance of major part of the molecule for all of the compounds from different types of carbonaceous chondrites (8 Antarctic and 2 none-Antarctic meteorites). A carbonaceous matter derived from graphite on a shock experiment using a rail gun (1g projectile at 7 km/s) showed similar IR spectrum to those of the meteoritic high-molecular organic matter. C-60 fullerene also gave a similar compound (with minor differences in IR spectra) on a shock experiment under the same conditions. A shock experiment using coronene also examined. PMID:11541332

  9. Structure of high-molecular carbonaceous compound in carbonaceous chondrites and formation of IR-spectroscopically similar compounds in the laboratory

    NASA Astrophysics Data System (ADS)

    Murae, T.

    1997-05-01

    Main components of carbonaceous matter in carbonaceous chondrites are high molecular organic matter. Examinations of the compounds using pyrolysis GC/MS and FT-IR indicated the structural resemblance of major part of the molecule for all of the compounds from different types of carbonaceous chondrites (8 Antarctic and 2 none-Antarctic meteorites). A carbonaceous matter derived from graphite on a shock experiment using a rail gun (1g projectile at 7 km/s) showed similar IR spectrum to those of the meteoritic high-molecular organic matter. C-60 fulleren also gave a similar compound (with minor differences in IR spectra) on a shock experiment under the same conditions. A shock experiment using coronene also examined.

  10. Axtrell, a new CV3 chondrite find from Texas

    NASA Technical Reports Server (NTRS)

    Simon, S. B.; Grossman, L.; Casanova, I.; Symes, S.; Benoit, P.; Sears, D. W. G.; Wacker, J. F.

    1995-01-01

    We describe a previously unreported meteorite found in Axtell, Texas, in 1943. Based on the mineralogical composition and texture of its matrix and the sizes and abundance of chondrules, we classify it as a CV3 carbonaceous chondrite. The dominant opaque phase in the chondrules is magnetite, and that in refractory inclusions is Ni-rich metal (awaruite). Axtell, therefore, belongs to the oxidized subgroup of CV3 chondrites, although unlike Allende it escaped strong sulfidation. The meteorite bears a strong textural resemblance to Allende, and its chondrule population and matrix appear to be quite similar to those of Allende, but its refractory inclusions, thermoluminescence properties, and cosmogenic Co-60 abundances are not. Our data are consistent with a terrestrial age for Axtell of approximately 100 years and a metamorphic grade slightly lower than that of Allende.

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

    NASA Astrophysics Data System (ADS)

    Changela, Hitesh G.

    2015-06-01

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

  12. Thermally metamorphosed carbonaceous chondrites from data for thermally mobile trace elements

    NASA Astrophysics Data System (ADS)

    Wang, Ming-Sheng; Lipschutz, Michael E.

    1998-11-01

    We report RNAA data for U, Co, Au, Sb, Ga, Rb, Cs, Se, Ag, Te, Zn, In, Bi, Tl and Cd (ordered by increasing ease of vaporization and loss from Murchison CM2 chondrite during open-system heating) in 9 Antarctic C2 and C3 chondrites. These meteorites exhibit properties (obtained by reflectance spectroscopy, oxygen isotope mass spectrometry and/or mineralogy-petrology) suggesting thermal metamorphism in their parent bodies. Five of these (Asuka 881655, Yamato (Y) 793495, Y-790992, PCA 91008 and Y-86789, paired with Y-86720) exhibit significant depletion of the most thermally-mobile 1-5 trace elements consistent with open-system loss during extended parent body heating under conditions duplicated by week-long heating of Murchison C2 chondrite heated at 500-700 deg C in a low pressure (initially 10-5 atm) H atmosphere. From earlier data, three other C3 chondrites - Allan Hills (ALH) 81003, ALH 85003 and Lewis Cliffs 85332 - show significant Cd depletion. Nine additional C2 and C3 chondrites show no evidence of mobile trace element depletion - including Y-793321, which by all other criteria was mildly metamorphosed thermally. Either metamorphism of these nine occurred under closed conditions and/or alteration took place under such mild conditions that even Cd could not be lost. The RNAA data suggest that 10 of the 46 Antarctic carbonaceous chondrites (including 4 of 37 from Victoria Land and 6 of 9 from Queen Maud Land) exhibit open-system loss of at least some thermally mobile trace elements by heating in their parent bodies while none of the 25 non-Antarctic falls experienced this. These results are consistent with the idea that the Antarctic sampling of near-Earth material differs from that being sampled today.

  13. Young asteroidal fluid activity revealed by absolute age from apatite in carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Zhang, Ai-Cheng; Li, Qiu-Li; Yurimoto, Hisayoshi; Sakamoto, Naoya; Li, Xian-Hua; Hu, Sen; Lin, Yang-Ting; Wang, Ru-Cheng

    2016-09-01

    Chondritic meteorites, consisting of the materials that have formed in the early solar system (ESS), have been affected by late thermal events and fluid activity to various degrees. Determining the timing of fluid activity in ESS is of fundamental importance for understanding the nature, formation, evolution and significance of fluid activity in ESS. Previous investigations have determined the relative ages of fluid activity with short-lived isotope systematics. Here we report an absolute 207Pb/206Pb isochron age (4,450+/-50 Ma) of apatite from Dar al Gani (DaG) 978, a type ~3.5, ungrouped carbonaceous chondrite. The petrographic, mineralogical and geochemical features suggest that the apatite in DaG 978 should have formed during metamorphism in the presence of a fluid. Therefore, the apatite age represents an absolute age for fluid activity in an asteroidal setting. An impact event could have provided the heat to activate this young fluid activity in ESS.

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2016-02-23

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

  16. 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

  17. 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.

  18. Cobalt-rich, nickel-poor metal (wairauite) in the Ningqiang carbonaceous chondrite

    NASA Technical Reports Server (NTRS)

    Xin, Hua; Eisenhour, Don D.; Buseck, Peter R.

    1995-01-01

    A structurally ordered cubic metal grain containing approximately 39 wt% Co, 61 wt% Fe, and less than 0.6 wt% Ni (approximately Fe3Co2) was found associated with troilite and pentlandite in the matrix of the Ningqiang carbonaceous chondrite. This mineral is similar to terrestrial wairauite. Experimental data in the Fe-Co system indicate that this CsCl-type Co-rich metal is stable below 700 C. Phase relations in the Fe-Co-Ni system show that Co cannot fractionate from Ni above 500 C. The dominant opaque minerals of awaruite, magnetite, and pentlandite in Ningqiang suggest relatively oxidizing conditions.

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

    NASA Technical Reports Server (NTRS)

    Abreu, Neyda M.; Brearley, Adrian J.

    2003-01-01

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

  20. Intrinsic W nucleosynthetic isotope variations in carbonaceous chondrites: Implications for W nucleosynthesis and nebular vs. parent body processing of presolar materials

    NASA Astrophysics Data System (ADS)

    Burkhardt, Christoph; Schönbächler, Maria

    2015-09-01

    The progressive dissolution of the carbonaceous chondrites Orgueil (CI1), Murchison (CM2) and Allende (CV3) with acids of increasing strength reveals correlated W isotope variations ranging from 3.5 ε182W and 6.5 ε183W in the initial leachate (acetic acid) to -60 ε182W and -40 ε183W in the leachate residue. The observed variations are readily explained by variable mixing of s-process depleted and s-process enriched components. One W s-process carrier is SiC, however, the observed anomaly patterns and mass-balance considerations require at least on additional s-process carrier, possibly a silicate or sulfide. The data reveal well-defined correlations, which provide a test for s-process nucleosynthesis models. The correlations demonstrate that current models need to be revised and highlight the need for more precise W isotope data of SiC grains. Furthermore the correlations provide a mean to disentangle nucleosynthetic and radiogenic contributions to 182W (ε182Wcorrected = ε182Wmeasured - (1.41 ± 0.05) × ε183Wmeasured; ε182Wcorrected = ε182Wmeasured - (-0.12 ± 0.06) × ε184Wmeasured), a prerequisite for the successful application of the Hf-W chronometer to samples with nucleosynthetic anomalies. The overall magnitude of the W isotope variations decreases in the order CI1 > CM2 > CV3. This can be interpreted as the progressive thermal destruction of an initially homogeneous mixture of presolar grains by parent-body processing. However, not only the magnitude but also the W anomaly patterns of the three chondrites are different. In particular leach step 2, that employs nitric acid, reveals a s-deficit signature for Murchison, but a s-excess for Orgueil and Allende. This could be the result of redistribution of anomalous W into a new phase by parent-body alteration, or, the fingerprint of dust processing in the solar nebula. Given that the thermal and aqueous alteration of Murchison is between the CI and CV3 chondrites, parent-body processing is probably

  1. Structure and Bonding of Carbon in Clays from CI Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Garview, Laurence a. J.; Buseck, Peter R.

    2005-01-01

    Carbonaceous chondrites (CC) contain a diverse suite of C-rich materials. Acid dissolution of these meteorites leaves a C-rich residue with chemical and structural affinities to kerogen. This material has primarily been analyzed in bulk, and much information has been provided regarding functional groups and elemental and isotopic compositions. However, comparatively little work has been done on C in unprocessed meteorites. Studies of CCs suggest a spatial relationship of some C-rich materials with products of aqueous alteration. Recent studies revealed discrete submicronsized, C-rich particles in Tagish Lake and a range of CM2 meteorites. A challenge is to correlate the findings from the bulk acid-residue studies with those of high-spatial resolution-mineralogical and spectroscopic observations of unprocessed meteorites. Hence, the relationship between the C-rich materials in the acid residues and its form and locations in the unprocessed meteorite remains unclear. Here we provide information on the structure and bonding of C associated with clays in CI carbonaceous chondrites. Additional information is included in the original extended abstract.

  2. Type IV kerogens as analogues for organic macromolecular materials in aqueously altered carbonaceous chondrites.

    PubMed

    Matthewman, Richard; Martins, Zita; Sephton, Mark A

    2013-04-01

    Understanding the processes involved in the evolution of organic matter in the early Solar System requires extensive experimental work. The scientifically valuable carbonaceous chondrites are principal targets for organic analyses, but these meteorites are rare. Meteoritic analog materials available in larger quantities, on which experiments can be performed, would be highly beneficial. The bulk of the organic inventory of carbonaceous chondrites is made up of solvent-insoluble macromolecular material. This high-molecular-weight entity provides a record of thermal and aqueous parent-body alteration of precursor organic structures present at the birth of the Solar System. To identify an effective analogue for this macromolecular material, we analyzed a series of terrestrial kerogens by pyrolysis-gas chromatography-mass spectrometry. Type I and II kerogens are unsuitable analogues owing to their highly aliphatic nature. Type III kerogens show some similarities to meteoritic macromolecular materials but display a substantial biological heritage. Type IV kerogens, in this study derived from Mesozoic paleosols and produced by the reworking and oxidation of organic matter, represent an effective analogue. Some isomeric differences exist between meteoritic macromolecular materials and type IV kerogens, and stepped pyrolysis indicates variations in thermal stability. In addition to being a suitable material for novel experimentation, type IV kerogens also have the potential to aid in the optimization of instruments for deployment on Mars. PMID:23551239

  3. Volatile-bearing phases in carbonaceous chondrites: Compositions, modal abundance, and reaction kinetics

    NASA Technical Reports Server (NTRS)

    Ganguly, Jibamitra

    1990-01-01

    The spectral and density characteristics of Phobos and Deimos (the two small natural satellites of Mars) strongly suggest that a significant fraction of the near-earth asteroids are made of carbonaceous chondrites, which are rich in volatile components and, thus, could serve as potential resources for propellants and life supporting systems in future planetary missions. However, in order to develop energy efficient engineering designs for the extraction of volatiles, knowledge of the nature and modal abundance of the minerals in which the volatiles are structurally bound and appropriate kinetic data on the rates of the devolatilization reactions is required. Theoretical calculations to predict the modal abundances and compositions of the major volatile-bearing and other mineral phases that could develop in the bulk compositions of C1 and C2 classes (the most volatile rich classes among the carbonaceous chondrites) were performed as functions of pressure and temperature. The rates of dehydration of talc at 585, 600, 637, and 670 C at P(total) = 1 bar were determine for the reaction: Talc = 3 enstatite + quartz + water. A scanning electron microscopic study was conducted to see if the relative abundance of phases can be determined on the basis of the spectral identification and x ray mapping. The results of this study and the other studies within the project are discussed.

  4. The formation and alteration of the Renazzo-like carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Schrader, Devin Lee

    This study investigates the pre-accretionary formation conditions of individual minerals within chondrules and whole-rock parent asteroid processes from the Renazzo-like carbonaceous (CR) chondrites. It presents a comprehensive work on the whole-rock O-isotope composition, sulfide-bearing opaque minerals, and type-II chondrules within the CR chondrites. Whole-rock O-isotope composition and minerals present in type-II chondrules are found to be related to the degree of parent asteroid aqueous alteration. Primary minerals within chondrules, formed prior to accretion of the CR chondrite parent asteroid, are used to constrain both the environment and the conditions present during chondrule formation. Chondrule formation, as recorded by chondrules in the CR chondrites, took place under dust- and ice-rich conditions relative to solar values. Type-II (FeO-rich) chondrules contain FeO-poor fragments compositionally similar to type-I (FeO-poor) chondrules; the formation of type-II chondrules may have occurred after the formation of type-I chondrules. The dust and ice abundances present during type-II chondrule formation were higher than those of type-I chondrules, although both populations probably exchanged with the same 16O-poor gas reservoir. Both the oxygen fugacity (fo 2) and sulfur fugacity (fs2) appear to have increased from type-I to type-II chondrule formation, and between individual type-II chondrules. The increase in fo2 and fs2 may be due to the dissipation of H2 in the early Solar System. Gas-solid oxidation/sulfidation of Fe,Ni metal is recorded in both type-I and type-II chondrules. This corrosion occurred either during chondrule cooling after formation, or during chondrule reheating events, and suggests that S was present in the gas phase. After chondrule formation the CR chondrite parent asteroid accreted 16O-poor ice and experienced variable degrees of aqueous alteration, possibly due to heterogeneity in accreted ice or ammonia abundances and/or differing

  5. Refractory inclusions in the CH/CB-like carbonaceous chondrite Isheyevo: I. Mineralogy and petrography

    NASA Astrophysics Data System (ADS)

    Krot, A. N.; Ulyanov, A. A.; Ivanova, M. A.

    2008-11-01

    The CH/CB-like chondrite Isheyevo consists of metal-rich (70 90 vol% Fe,Ni-metal) and metal-poor (7 20 vol% Fe,Ni-metal) lithologies which differ in size and relative abundance of Fe,Nimetal and chondrules, as well as proportions of porphyritic versus non-porphyritic chondrules. Here, we describe the mineralogy and petrography of Ca,Al-rich inclusions (CAIs) and amoeboid olivine aggregates (AOAs) in these lithologies. Based on mineralogy, refractory inclusions can be divided into hibonite-rich (39%), grossite-rich (16%), melilite-rich (19%), spinel-rich (14%), pyroxeneanorthite- rich (8%), fine-grained spinel-rich CAIs (1%), and AOAs (4%). There are no systematic differences in the inclusion types or their relative abundances between the lithologies. About 55% of the Isheyevo CAIs are very refractory (hibonite-rich and grossite-rich) objects, 20 240 μm in size, which appear to have crystallized from rapidly cooling melts. These inclusions are texturally and mineralogically similar to the majority of CAIs in CH and CB chondrites. They are distinctly different from CAIs in other carbonaceous chondrite groups dominated by the spinel-pyroxene ± melilite CAIs and AOAs. The remaining 45% of inclusions are less refractory objects (melilite-, spinel- and pyroxene-rich CAIs and AOAs), 40 300 μm in size, which are texturally and mineralogically similar to those in other chondrite groups. Both types of CAIs are found as relict objects inside porphyritic chondrules indicating recycling during chondrule formation. We infer that there are at least two populations of CAIs in Isheyevo which appear to have experienced different thermal histories. All of the Isheyevo CAIs apparently formed at an early stage, prior to chondrule formation and prior to a hypothesized planetary impact that produced magnesian cryptocrystalline and skeletal chondrules and metal grains in CB, and possibly CH chondrites. However, some of the CAIs appear to have undergone melting during chondrule

  6. The Effect of Aqueous Alteration in Antarctic Carbonaceous Chondrites from Comparative ICP-MS Bulk Chemistry

    NASA Technical Reports Server (NTRS)

    Alonso-Azcarate, J.; Trigo-Rodriguez, J. M.; Moyano-Cambero, C. E.; Zolensky, M.

    2014-01-01

    Terrestrial ages of Antarctic carbonaceous chondrites (CC) indicate that these meteorites have been preserved in or on ice for, at least, tens of thousands of years. Due to the porous structure of these chondrites formed by the aggregation of silicate-rich chondrules, refractory inclusions, metal grains, and fine-grained matrix materials, the effect of pervasive terrestrial water is relevant. Our community defends that pristine CC matrices are representing samples of scarcely processed protoplanetary disk materials as they contain stellar grains, but they might also trace parent body processes. It is important to study the effects of terrestrial aqueous alteration in promoting bulk chemistry changes, and creating distinctive alteration minerals. Particularly because it is thought that aqueous alteration has particularly played a key role in some CC groups in modifying primordial bulk chemistry, and homogenizing the isotopic content of fine-grained matrix materials. Fortunately, the mineralogy produced by parent-body and terrestrial aqueous alteration processes is distinctive. With the goal to learn more about terrestrial alteration in Antarctica we are obtaining reflectance spectra of CCs, but also performing ICP-MS bulk chemistry of the different CC groups. A direct comparison with the mean bulk elemental composition of recovered falls might inform us on the effects of terrestrial alteration in finds. With such a goal, in the current work we have analyzed some members representative of CO and CM chondrite groups.

  7. The Spatial Distribution and Mineralogical Association of Organics in the Tagish Lake and Bells Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    Chondritic meteorites represent some of the most primitive Solar System materials available for laboratory analysis. While the presence of simple organic molecules has been well documented in such materials [1], little is known about their spatial distribution and to what extent, if any, they exhibit specific mineralogical associations. This dichotomy arises since organic analysis typically involves solvent extraction as a preliminary step. To address these issues we have used two-step laser mass spectrometry (L 2MS) to map in situ the spatial distribution of aromatic and conjugated organics at the micron scale in freshly exposed surfaces of the Tagish Lake and Bells carbonaceous chondrites. Our specific goals are two-fold; firstly to investigate if and how abundance of organic species varies within the meteorite matrix both as an ensemble, and with respect to functional group (e.g., R-OH vs. RCH3) and between members of the same homologous series (e.g., R-H vs. R-(CH2)H). Secondly, to determine whether observed spatial variations can be related to specific mineralogical and/or physical characteristics of the host matrix. In regard to the latter we are particularly interested in the role that carbonaceous nanoglobules [2] play as reservoirs of organic matter. Such globules, which are believed to have formed by photochemical processing of organic-rich ices in the presolar cold molecular cloud or the outermost reaches of the early protosolar disk, are abundant in both the Bells and Tagish Lake chondrites and are noteworthy for having particularly high enrichments in 2H and 15N [3,4].

  8. Strain Measurements of Chondrules and Refraction Inclusion in Allende

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

    This study uses traditional strain measurement techniques, combined with X-ray computerized tomography (CT), to evaluate petrographic evidence in the Allende CV3 chondrite for preferred orientation and to measure strain in three dimensions. The existence of petrofabrics and lineations was first observed in carbonaceous meteorites in the 1960's. Yet, fifty years later only a few studies have reported that meteorites record such features. Impacts are often cited as the mechanism for this feature, although plastic deformation from overburden and nebular imbrication have also been proposed. Previous work conducted on the Leoville CV3 and the Parnallee LL3 chondrites, exhibited a minimum uniaxial shortening of 33% and 21%, respectively. Petrofabrics in Allende CV3 have been looked at before; previous workers using Electron Back Scatter Diffraction (EBSD) found a major-axis alignment of olivine inside dark inclusions and an "augen"-like preferred orientation of olivine grains around more competent chondrules

  9. Comparison of visible and near-infrared reflectance spectra of CM2 carbonaceous chondrites and primitive asteroids

    NASA Technical Reports Server (NTRS)

    Vilas, F.; Hiroi, T.; Zolensky, M. E.

    1993-01-01

    Spectra of primitive asteroids (defined as C, P, and D classes and associated subclasses) were compared to the limited number of spectra of CM2 carbonaceous chondrites. An absorption feature located at 0.7 microns attributed to an Fe(+2) - Fe(+3) charge transfer absorption in iron oxides in phyllosilicates is apparent in some of the CM2 carbonaceous chondrite spectra and many of the asteroid spectra. Sawyer found a correlation between the area of the 0.7 micron feature and the mean semimajor axis of the asteroids. Spectra of a larger sample of carbonaceous chondrites, including 7 CM2 chondrites, covering a spectral interval of 0.30-2.5 microns were recently obtained using the Relab instrument at Brown University. These spectra were compared with spectrophotometric asteroid observations in a separate abstract. Those spectra of CM2 chondrites were isolated into the UV, visible and near-infrared spectral regions in order to compare them with high-quality narrowband reflectance spectra.

  10. Fe and O EELS Studies of Ion Irradiated Murchison CM2 Carbonaceous Chondrite Matrix

    NASA Technical Reports Server (NTRS)

    Keller, L. P.; Christofferson, R.; Dukes, C. A.; Baragiola, R. A.; Rahman, Z.

    2015-01-01

    Introduction: The physical and chemical response of hydrated carbonaceous chondrite materials to space weathering processes is poorly understood. Improving this understanding is a key part of establishing how regoliths on primitive carbonaceous asteroids respond to space weathering processes, knowledge that supports future sample return missions (Hayabusa 2 and OSIRISREx) that are targeting objects of this type. We previously reported on He+ irradiation of Murchison matrix and showed that the irradiation resulted in amorphization of the matrix phyllosilicates, loss of OH, and surface vesiculation. Here, we report electron energy-loss spectroscopy (EELS) measurements of the irradiated material with emphasis on the Fe and O speciation. Sample and Methods: A polished thin section of the Murchison CM2 carbonaceous chondrite was irradiated with 4 kilovolts He(+) (normal incidence) to a total dose of 1 x 10(exp 18) He(+) per square centimeter. We extracted thin sections from both irradiated and unirradiated regions in matrix using focused ion beam (FIB) techniques with electron beam deposition for the protective carbon strap to minimize surface damage artifacts from the FIB milling. The FIB sections were analyzed using a JEOL 2500SE scanning and transmission electron microscope (STEM) equipped with a Gatan Tridiem imaging filter. EELS spectra were collected from 50 nanometer diameter regions with an energy resolution of 0.7 electronvolts FWHM at the zero loss. EELS spectra were collected at low electron doses to minimize possible artifacts from electron-beam irradiation damage. Results and Discussion: Fe L (sub 2,3) EELS spectra from matrix phyllosilicates in CM chondrites show mixed Fe(2+)/Fe(3+) oxidation states with Fe(3+)/Sigma Fe approximately 0.5. Fe L(sub 2,3) spectra from the irradiated/ amorphized matrix phyllosilicates show higher Fe(2+)/Fe(3+) ratios compared to spectra obtained from pristine material at depths beyond the implantation/amorphization layer. We

  11. 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.

  12. 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.

  13. Rapid Contamination During Storage of Carbonaceous Chondrites Prepared for Micro FTIR Measurements

    NASA Technical Reports Server (NTRS)

    Kebukawa, Yoko; Nakashima, Satoru; Otsuka, Takahiro; Nakamura-Messenger, Keiko; Zolensky, ichael E.

    2008-01-01

    The carbonaceous chondrites Tagish Lake and Murchison, which contain abundant hydrous minerals, when pressed on aluminum plates and analyzed by micro FTIR, were found to have been contaminated during brief (24 hours) storage. This contamination occurred when the samples were stored within containers which included silicone rubber, silicone grease or adhesive tape. Long-path gas cell FTIR measurements for silicone rubber revealed the presence of contaminant volatile molecules having 2970 cm(sup -1) (CH3) and 1265 cm(sup -1) (Si-CH3) peaks. These organic contaminants are found to be desorbed by in-situ heating infrared measurements from room temperature to 200-300 C. Careful preparation and storage are therefore needed for precious astronomical samples such as meteorites, IDPs and mission returned samples from comets, asteroids and Mars, if useful for FTIR measurements are to be made.

  14. 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

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

    NASA Technical Reports Server (NTRS)

    Becker, R. H.; Epstein, S.

    1982-01-01

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

  16. Hydrogen isotopes in lunar volcanic glasses and melt inclusions reveal a carbonaceous chondrite heritage.

    PubMed

    Saal, Alberto E; Hauri, Erik H; Van Orman, James A; Rutherford, Malcolm J

    2013-06-14

    Water is perhaps the most important molecule in the solar system, and determining its origin and distribution in planetary interiors has important implications for understanding the evolution of planetary bodies. Here we report in situ measurements of the isotopic composition of hydrogen dissolved in primitive volcanic glass and olivine-hosted melt inclusions recovered from the Moon by the Apollo 15 and 17 missions. After consideration of cosmic-ray spallation and degassing processes, our results demonstrate that lunar magmatic water has an isotopic composition that is indistinguishable from that of the bulk water in carbonaceous chondrites and similar to that of terrestrial water, implying a common origin for the water contained in the interiors of Earth and the Moon. PMID:23661641

  17. Polycyclic aromatic hydrocarbons (PAHs) in Antarctic Martian meteorites, carbonaceous chondrites, and polar ice.

    PubMed

    Becker, L; Glavin, D P; Bada, J L

    1997-01-01

    Recent analyses of the carbonate globules present in the Martian meteorite ALH84001 have detected polycyclic aromatic hydrocarbons (PAHs) at the ppm level (McKay et al., 1996). The distribution of PAHs observed in ALH84001 was interpreted as being inconsistent with a terrestrial origin and were claimed to be indigenous to the meteorite, perhaps derived from an ancient martian biota. We have examined PAHs in the Antarctic shergottite EETA79001, which is also considered to be from Mars, as well as several Antarctic carbonaceous chondrites. We have found that many of the same PAHs detected in the ALH84001 carbonate globules are present in Antarctic carbonaceous chondrites and in both the matrix and carbonate (druse) component of EETA79001. We also investigated PAHs in polar ice and found that carbonate is an effective scavenger of PAHs in ice meltwater. Moreover, the distribution of PAHs in the carbonate extract of Antarctic Allan Hills ice is remarkably similar to that found in both EETA79001 and ALH84001. The reported presence of L-amino acids of apparent terrestrial origin in the EETA79001 druse material (McDonald and Bada, 1995) suggests that this meteorite is contaminated with terrestrial organics probably derived from Antarctic ice meltwater that had percolated through the meteorite. Our data suggests that the PAHs observed in both ALH84001 and EETA79001 are derived from either the exogenous delivery of organics to Mars or extraterrestrial and terrestrial PAHs present in the ice meltwater or, more likely, from a mixture of these sources. It would appear that PAHs are not useful biomarkers in the search for extinct or extant life on Mars. PMID:11541466

  18. Amino acid compositions in heated carbonaceous chondrites and their compound-specific nitrogen isotopic ratios

    NASA Astrophysics Data System (ADS)

    Chan, Queenie Hoi Shan; Chikaraishi, Yoshito; Takano, Yoshinori; Ogawa, Nanako O.; Ohkouchi, Naohiko

    2016-01-01

    A novel method has been developed for compound-specific nitrogen isotope compositions with an achiral column which was previously shown to offer high precision for nitrogen isotopic analysis. We applied the method to determine the amino acid contents and stable nitrogen isotopic compositions of individual amino acids from the thermally metamorphosed (above 500 °C) Antarctic carbonaceous chondrites Ivuna-like (CI)1 (or CI-like) Yamato (Y) 980115 and Ornans-like (CO)3.5 Allan Hills (ALH) A77003 with the use of gas chromatography/combustion/isotope ratio mass spectrometry. ALHA77003 was deprived of amino acids due to its extended thermal alteration history. Amino acids were unambiguously identified in Y-980115, and the δ15N values of selected amino acids (glycine +144.8 ‰; α-alanine +121.2 ‰) are clearly extraterrestrial. Y-980115 has experienced an extended period of aqueous alteration as indicated by the presence of hydrous mineral phases. It has also been exposed to at least one post-hydration short-lived thermal metamorphism. Glycine and alanine were possibly produced shortly after the accretion event of the asteroid parent body during the course of an extensive aqueous alteration event and have abstained from the short-term post-aqueous alteration heating due to the heterogeneity of the parent body composition and porosity. These carbonaceous chondrite samples are good analogs that offer important insights into the target asteroid Ryugu of the Hayabusa-2 mission, which is a C-type asteroid likely composed of heterogeneous materials including hydrated and dehydrated minerals.

  19. Dehydration kinetics and thermochemistry of selected hydrous phases, and simulated gas release pattern in carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Bose, Kunal; Ganguly, J.

    1992-01-01

    As part of our continued program of study on the volatile bearing phases and volatile resource potential of carbonaceous chondrite, results of our experimental studies on the dehydration kinetics of talc as a function of temperature and grain size (50 to 0.5 microns), equilibrium dehydration boundary of talc to 40 kbars, calorimetric study of enthalpy of formation of both natural and synthetic talc as a function of grain size, and preliminary results on the dehydration kinetics of epsomite are reported. In addition, theoretical calculations on the gas release pattern of Murchison meteorite, which is a C2(CM) carbonaceous chondrite, were performed. The kinetic study of talc leads to a dehydration rate constant for 40-50 microns size fraction of k = (3.23 x 10(exp 4))exp(-Q/RT)/min with the activation energy Q = 376 (plus or minus 20) kJ/mole. The dehydration rate was found to increase somewhat with decreasing grain size. The enthalpy of formation of talc from elements was measured to be -5896(10) kJ/mol. There was no measurable effect of grain size on the enthalpy beyond the limits of precision of the calorimetric studies. Also the calorimetric enthalpy of both synthetic and natural talc was found to be essentially the same, within the precision of measurements, although the natural talc had a slightly larger field of stability in our phase equilibrium studies. The high pressure experimental data the dehydration equilibrium of talc (talc = enstatite + coesite + H2O) is in strong disagreement with that calculated from the available thermochemical data, which were constrained to fit the low pressure experimental results. The calculated gas release pattern of Murchison meteorite were in reasonable agreement with that determined by stepwise heating in a gas chromatograph.

  20. Polycyclic aromatic hydrocarbons (PAHs) in Antarctic Martian meteorites, carbonaceous chondrites, and polar ice.

    PubMed

    Becker, L; Glavin, D P; Bada, J L

    1997-01-01

    Recent analyses of the carbonate globules present in the Martian meteorite ALH84001 have detected polycyclic aromatic hydrocarbons (PAHs) at the ppm level (McKay et al., 1996). The distribution of PAHs observed in ALH84001 was interpreted as being inconsistent with a terrestrial origin and were claimed to be indigenous to the meteorite, perhaps derived from an ancient martian biota. We have examined PAHs in the Antarctic shergottite EETA79001, which is also considered to be from Mars, as well as several Antarctic carbonaceous chondrites. We have found that many of the same PAHs detected in the ALH84001 carbonate globules are present in Antarctic carbonaceous chondrites and in both the matrix and carbonate (druse) component of EETA79001. We also investigated PAHs in polar ice and found that carbonate is an effective scavenger of PAHs in ice meltwater. Moreover, the distribution of PAHs in the carbonate extract of Antarctic Allan Hills ice is remarkably similar to that found in both EETA79001 and ALH84001. The reported presence of L-amino acids of apparent terrestrial origin in the EETA79001 druse material (McDonald and Bada, 1995) suggests that this meteorite is contaminated with terrestrial organics probably derived from Antarctic ice meltwater that had percolated through the meteorite. Our data suggests that the PAHs observed in both ALH84001 and EETA79001 are derived from either the exogenous delivery of organics to Mars or extraterrestrial and terrestrial PAHs present in the ice meltwater or, more likely, from a mixture of these sources. It would appear that PAHs are not useful biomarkers in the search for extinct or extant life on Mars.

  1. Polycyclic aromatic hydrocarbons (PAHs) in Antarctic Martian meteorites, carbonaceous chondrites, and polar ice

    SciTech Connect

    Becker, L. |; Glavin, D.P.; Bada, J.L.

    1997-01-01

    Recent analyses of the carbonate globules present in the Martian meteorite ALH84001 have detected polycyclic aromatic hydrocarbons (PAHs) at the ppm level. The distribution of PAHs observed in ALH84001 was interpreted as being inconsistent with a terrestrial origin and were claimed to be indigenous to the meteorite, perhaps derived from an ancient martian biota. We have examined PAHs in the Antarctic shergottite EETA79001, which is also considered to be from Mars, as well as several Antarctic carbonaceous chondrites. We have found that many of the same PAHs detected in the ALH84001 carbonate globules are present in Antarctic carbonaceous chondrites and in both the matrix and carbonate (druse) component of EETA79001. We also investigated PAHs in polar ice and found that carbonate is an effective scavenger of PAHs in ice meltwater. Moreover, the distribution of PAHs in the carbonate extract of Antarctic Allan Hills ice is remarkably similar to that found in both EETA79001 and ALH84001. The reported presence of L-amino acids of apparent terrestrial origin in the EETA79001 druse material suggests that this meteorite is contaminated with terrestrial organics probably derived from Antarctic ice meltwater that had percolated through the meteorite. Our data suggests that the PAHs observed in both ALH84001 and EETA79001 are derived from either the exogenous delivery of organics to Mars or extraterrestrial and terrestrial PAHs present in the ice meltwater or, more likely, from a mixture of these sources. It would appear that PAHs are not useful biomarkers in the search for extinct or extant life on Mars. 33 refs., 3 figs., 1 tab.

  2. Refractory inclusions in the pristine carbonaceous chondrites DOM 08004 and DOM 08006

    NASA Astrophysics Data System (ADS)

    Simon, Steven B.; Grossman, Lawrence

    2015-06-01

    The Antarctic carbonaceous chondrites DOM 08004 and DOM 08006 have been paired and classified as CO3.0s. There is some uncertainty as to whether they should be paired and whether they are best classified as CO chondrites, but they provide an opportunity for the study of refractory inclusions that have not been modified by parent body processes. In this work, refractory inclusions in thin sections of DOM 08004 and 08006 are studied and compared with inclusions in ALHA77307 (CO3.0) and Acfer 094 (C3.0, ungrouped). Results show that the DOM samples have refractory inclusion populations that are similar to each other but not typical of CO3 chondrites; main differences are that the DOM samples are slightly richer in inclusions in general and, more specifically, in the proportions of grossite-bearing inclusions. In DOM 08004 and DOM 08006, 12.4% and 6.6%, respectively, of the inclusions are grossite-bearing. This is higher than the proportion found in Acfer 094 (5.2%), whereas none were found in ALHA77307. Like those in Acfer 094, DOM inclusions are small (mostly <100 μm across) and fine-grained, and thin rims of aluminous diopside±melilite are very common. Also like Acfer 094, most phases in the DOM inclusions have FeO contents higher than expected for primary refractory phases. In addition to typical inclusions, some unusual ones were found in DOM 08004, including a perovskite-rich one with a rare, recently reported Sc-, Al-oxide and davisite; a very grossite-rich inclusion with a small, hibonite-rich core enclosed in a grossite mantle; and a relict, grossite-rich inclusion enclosed in an Al-rich chondrule. The CAI populations in the DOM samples are similar to each other and, based on grossite abundances, FeO enrichments and occurrences of rims are more Acfer 094-like than CO3-like. An earlier history on an FeO-rich parent was previously favored over nebular equilibria or in situ reactions to account for FeO enrichments in CAIs in the otherwise pristine chondrite

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  4. In situ observation of D-rich carbonaceous globules embedded in NWA 801 CR2 chondrite

    NASA Astrophysics Data System (ADS)

    Hashiguchi, Minako; Kobayashi, Sachio; Yurimoto, Hisayoshi

    2013-12-01

    Eighty-five D-rich carbonaceous particles were identified in the matrix of the NWA 801 CR2 chondrite using isotope microscopy. The occurrence of 67 D-rich carbonaceous particles was characterized using secondary electron microscopy combined with X-ray elemental mapping. The close association of H and C, and D-enrichment suggests that the D-rich carbonaceous particles correspond to organic matter. The D-rich organic particles were scattered ubiquitously throughout the matrix at a concentration of approximately 660 ppm. The morphology of the D-rich carbonaceous particles is globular up to about 1 μm in diameter and is classified into four types: ring globules, round globules, irregular-shaped globules, and globule aggregates. The ring globules are ring-shaped organic matter containing silicate and/or oxide, with or without a void in the center. This is the first report of silicate and oxide grains surrounded by D-rich organic matter. The globule aggregates are composed of several D-rich organic globules mixed with silicates. Morphology of ring globules is very similar to core-mantle grain produced in the molecular cloud or in the outer solar nebula inferring by astronomy, suggesting that the organic globules have formed by UV photolysis in the ice mantle. Silicates or oxides attached to D-rich organic globules are the first observation among chondrites so far and may be unique nature of CR2 chondrites. The hydrogen isotopic compositions of the ring globules, round globules, irregular-shaped globules, and globule aggregates are δD = 3000-4800, 2900-8100, 2700-11,000, and 2500-11,000‰, respectively. Variations of D/H ratio of these organic globules seemed to be attributed to variations of D/H ratio of the organic radicals or differences of content of the D-rich organic radicals. There are no significant differences in the hydrogen isotopic compositions among the four types of D-rich carbonaceous matter. The D-enrichments suggest that these organic globules have

  5. Chondrites: initial strontium-87/strontium-86 ratios and the early history of the solar system.

    PubMed

    Wetherill, G W; Mark, R; Lee-Hu, C

    1973-10-19

    A sodium-poor, calcium-rich inclusion in the carbonaceous chondrite Allende had a (87)Sr/(86)Sr ratio at the time of its formation of 0.69880, as low a value as that found in any other meteorite. The higher (87)Sr/(86)Sr ratios found in ordinary chondrites indicate that their formation or isotopic equilibration occurred tens of millions of years later.

  6. Chondrites - Initial strontium-87/strontium-86 ratios and the early history of the solar system.

    NASA Technical Reports Server (NTRS)

    Wetherill, G. W.; Mark, R.; Lee-Hu, C.

    1973-01-01

    A sodium-poor, calcium-rich inclusion in the carbonaceous chondrite Allende had a Sr-87/Sr-86 ratio at the time of its formation of 0.69880, as low a value as that found in any other meteorite. The higher Sr-87/Sr-86 ratios found in ordinary chondrites indicate that their formation or isotopic equilibration occurred tens of millions of years later.

  7. Magnetite-sulfide chondrules and nodules in CK carbonaceous chondrites - Implications for the timing of CK oxidation

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.

    1993-01-01

    CK carbonaceous chondrites contain rare (about 0.1 vol pct) magnetite-sulfide chondrules that range from about 240 to 500 microns in apparent diameter and have ellipsoidal to spheroidal morphologies, granular textures, and concentric layering. They resemble the magnetite-sulfide nodules occurring inside mafic silicate chondrules in CK chondrites. It seems likely that the magnetite-sulfide chondrules constitute the subset of magnetite-sulfide nodules that escaped as immiscible droplets from their molten silicate chondrule hosts during chondrule formation. The intactness of the magnetite-sulfide chondrules and nodules implies that oxidation of CK metal occurred before agglomeration. Hence, the pervasive silicate darkening of CK chondrites was caused by the shock mobilization of magnetite and sulfide, not metallic Fe-Ni and sulfide as in shock-darkened ordinary chondrites.

  8. Magnesium and 54Cr isotope compositions of carbonaceous chondrite chondrules - Insights into early disk processes

    NASA Astrophysics Data System (ADS)

    Olsen, Mia B.; Wielandt, Daniel; Schiller, Martin; Van Kooten, Elishevah M. M. E.; Bizzarro, Martin

    2016-10-01

    We report on the petrology, magnesium isotopes and mass-independent 54Cr/52Cr compositions (μ54Cr) of 42 chondrules from CV (Vigarano and NWA 3118) and CR (NWA 6043, NWA 801 and LAP 02342) chondrites. All sampled chondrules are classified as type IA or type IAB, have low 27Al/24Mg ratios (0.04-0.27) and display little or no evidence for secondary alteration processes. The CV and CR chondrules show variable 25Mg/24Mg and 26Mg/24Mg values corresponding to a range of mass-dependent fractionation of ∼500 ppm (parts per million) per atomic mass unit. This mass-dependent Mg isotope fractionation is interpreted as reflecting Mg isotope heterogeneity of the chondrule precursors and not the result of secondary alteration or volatility-controlled processes during chondrule formation. The CV and CR chondrule populations studied here are characterized by systematic deficits in the mass-independent component of 26Mg (μ26Mg∗) relative to the solar value defined by CI chondrites, which we interpret as reflecting formation from precursor material with a reduced initial abundance of 26Al compared to the canonical 26Al/27Al of ∼5 × 10-5. Model initial 26Al/27Al values of CV and CR chondrules vary from (1.5 ± 4.0) × 10-6 to (2.2 ± 0.4) × 10-5. The CV chondrules display significant μ54Cr variability, defining a range of compositions that is comparable to that observed for inner Solar System primitive and differentiated meteorites. In contrast, CR chondrites are characterized by a narrower range of μ54Cr values restricted to compositions typically observed for bulk carbonaceous chondrites. Collectively, these observations suggest that the CV chondrules formed from precursors that originated in various regions of the protoplanetary disk and were then transported to the accretion region of the CV parent asteroid whereas CR chondrule predominantly formed from precursor with carbonaceous chondrite-like μ54Cr signatures. The observed μ54Cr variability in chondrules from CV

  9. Magnesium and 54Cr isotope compositions of carbonaceous chondrite chondrules – Insights into early disk processes

    PubMed Central

    Olsen, Mia B.; Wielandt, Daniel; Schiller, Martin; Van Kooten, Elishevah M.M.E.; Bizzarro, Martin

    2016-01-01

    We report on the petrology, magnesium isotopes and mass-independent 54Cr/52Cr compositions (μ54Cr) of 42 chondrules from CV (Vigarano and NWA 3118) and CR (NWA 6043, NWA 801 and LAP 02342) chondrites. All sampled chondrules are classified as type IA or type IAB, have low 27Al/24Mg ratios (0.04–0.27) and display little or no evidence for secondary alteration processes. The CV and CR chondrules show variable 25Mg/24Mg and 26Mg/24Mg values corresponding to a range of mass-dependent fractionation of ~500 ppm (parts per million) per atomic mass unit. This mass-dependent Mg isotope fractionation is interpreted as reflecting Mg isotope heterogeneity of the chondrule precursors and not the result of secondary alteration or volatility-controlled processes during chondrule formation. The CV and CR chondrule populations studied here are characterized by systematic deficits in the mass-independent component of 26Mg (μ26Mg*) relative to the solar value defined by CI chondrites, which we interpret as reflecting formation from precursor material with a reduced initial abundance of 26Al compared to the canonical 26Al/27Al of ~5 × 10−5. Model initial 26Al/27Al values of CV and CR chondrules vary from (1.5 ± 4.0) × 10−6 to (2.2 ± 0.4) × 10−5. The CV chondrules display significant μ54Cr variability, defining a range of compositions that is comparable to that observed for inner Solar System primitive and differentiated meteorites. In contrast, CR chondrites are characterized by a narrower range of μ54Cr values restricted to compositions typically observed for bulk carbonaceous chondrites. Collectively, these observations suggest that the CV chondrules formed from precursors that originated in various regions of the protoplanetary disk and were then transported to the accretion region of the CV parent asteroid whereas CR chondrule predominantly formed from precursor with carbonaceous chondrite-like μ54Cr signatures. The observed μ54Cr variability in chondrules from

  10. Young asteroidal fluid activity revealed by absolute age from apatite in carbonaceous chondrite

    PubMed Central

    Zhang, Ai-Cheng; Li, Qiu-Li; Yurimoto, Hisayoshi; Sakamoto, Naoya; Li, Xian-Hua; Hu, Sen; Lin, Yang-Ting; Wang, Ru-Cheng

    2016-01-01

    Chondritic meteorites, consisting of the materials that have formed in the early solar system (ESS), have been affected by late thermal events and fluid activity to various degrees. Determining the timing of fluid activity in ESS is of fundamental importance for understanding the nature, formation, evolution and significance of fluid activity in ESS. Previous investigations have determined the relative ages of fluid activity with short-lived isotope systematics. Here we report an absolute 207Pb/206Pb isochron age (4,450±50 Ma) of apatite from Dar al Gani (DaG) 978, a type ∼3.5, ungrouped carbonaceous chondrite. The petrographic, mineralogical and geochemical features suggest that the apatite in DaG 978 should have formed during metamorphism in the presence of a fluid. Therefore, the apatite age represents an absolute age for fluid activity in an asteroidal setting. An impact event could have provided the heat to activate this young fluid activity in ESS. PMID:27682449

  11. Dipeptides and Diketopiperazines in the Yamato-791198 and Murchison Carbonaceous Chondrites

    NASA Astrophysics Data System (ADS)

    Shimoyama, Akira; Ogasawara, Ryo

    2002-04-01

    The Yamato-791198 and Murchison carbonaceous chondrites were analyzed for dipeptides and diketopiperazines as well as amino acids and hydantoins by gas chromatography combined with mass spectrometry. Glycylglycine (gly-gly) and cyclo(gly-gly) were detected at the concentrations of 11 and 18 pmol g^-1, respectively, in Yamato-791198, and 4 and 23 pmol g^-1, respectively, in Murchison. No other dipeptide and diketopiperazine were detected. Five hydantoins were detected at 8 to 65 pmol g^-1 in Yamato-791198 and seven in Murchison at 6 to 104 pmol g^-1. Total concentration of the glycine (gly) dimers is approximately four orders of magnitude less than the concentration of free gly in Yamato-791198, and three orders of magnitude less than that in Murchison. The absence of L- and LL-stereoisomers of dipeptides consisting of protein amino acids indicates that gly-gly and cyclo(gly-gly) detected are native to the chondrites and not from terrestrial contaminants. A possibility was discussed that the gly dimers might have been formed by condensation of gly monomers but not formed through N-carboxyanhydrides of gly.

  12. Formation and Processing of Amorphous Silicates in Primitive Carbonaceous Chondrites and Cometary Dust

    NASA Technical Reports Server (NTRS)

    Keller, Lindsay P.; Messenger, S.

    2012-01-01

    Chondritic-porous interplanetary dust particles (CP IDPs) exhibit strongly heterogeneous and unequilibrated mineralogy at sub-micron scales, are enriched in carbon, nitrogen and volatile trace elements, and contain abundant presolar materials [1-4]. These observations suggest that CP IDPs have largely escaped the thermal processing and water-rock interactions that have severely modified or destroyed the original mineralogy of primitive meteorites. CP IDPs are believed to represent direct samples of the building blocks of the Solar System - a complex mixture of nebular and presolar materials largely unperturbed by secondary processing. The chemical and isotopic properties of CP IDPs and their atmospheric entry velocities are also consistent with cometary origins. GEMS (glass with embedded metal and sulfides) grains are a major silicate component of CP IDPs. GEMS grains are < 0.5 microns in diameter objects that consist of numerous 10 to 50 nm-sized Fe-Ni metal and Fe-Ni sulfide grains dispersed in a Mg-Si-Al-Fe amorphous silicate matrix [2, 5]. Based on their chemistry and isotopic compositions, most GEMS appear to be non-equilibrium condensates from the early solar nebula [2]. If GEMS grains are a common nebular product, then they should also be abundant in the matrices of the most physically primitive chondritic meteorites. Although amorphous silicates are common in the most primitive meteorites [6-9], their relationship to GEMS grains and the extent to which their compositions and microstructure have been affected by parent body processing (oxidation and aqueous alteration) is poorly constrained. Here we compare and contrast the chemical, microstructural and isotopic properties of amorphous silicates in primitive carbonaceous chondrites to GEMS grains in IDPs.

  13. Correlating Mineralogy and Amino Acid Contents of Milligram-Scale Murchison Carbonaceous Chondrite Samples

    NASA Technical Reports Server (NTRS)

    Burton, Aaron, S.; Berger, Eve L.; Locke, Darren R.; Elsila, Jamie E.; Glavin, Daniel P.; Dworkin, Jason P.

    2015-01-01

    Amino acids, the building blocks of proteins, have been found to be indigenous in most of the carbonaceous chondrite groups. The abundances of amino acids, as well as their structural, enantiomeric and isotopic compositions differ significantly among meteorites of different groups and petrologic types. This suggests that there is a link between parent-body conditions, mineralogy and the synthesis and preservation of amino acids (and likely other organic molecules). However, elucidating specific causes for the observed differences in amino acid composition has proven extremely challenging because samples analyzed for amino acids are typically much larger ((is) approximately 100 mg powders) than the scale at which meteorite heterogeneity is observed (sub mm-scale differences, (is) approximately 1-mg or smaller samples). Thus, the effects of differences in mineralogy on amino acid abundances could not be easily discerned. Recent advances in the sensitivity of instrumentation have made possible the analysis of smaller samples for amino acids, enabling a new approach to investigate the link between mineralogical con-text and amino acid compositions/abundances in meteorites. Through coordinated mineral separation, mineral characterization and highly sensitive amino acid analyses, we have performed preliminary investigations into the relationship between meteorite mineralogy and amino acid composition. By linking amino acid data to mineralogy, we have started to identify amino acid-bearing mineral phases in different carbonaceous meteorites. The methodology and results of analyses performed on the Murchison meteorite are presented here.

  14. Chondrules in the LEW85332 Ungrouped Carbonaceous Chondrite: Fractionation Processes in the Solar Nebula

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

    We studied 14 chondrules separated from LEW85332, an ungrouped type-3 carbonaceous chondrite related to CR chondrites; 23 elements were determined by neutron activation and the chondrules were characterized petrographically. Oxygen isotopic compositions were determined by R. N. Clayton and T. K. Mayeda for seven chondrules. Chondrule abundance ratios tend to form one of two distinct patterns. In low FeO chondrules, refractory lithophile patterns are flat (i.e., unfractionated); siderophile abundances are high and show a small decrease with increasing volatility. Although high FeO chondrules also have flat refractory lithophile abundance patterns, siderophile abundances are highly fractionated; refractory Ir is very low and Fe is very high relative to other siderophiles. We suggest that the low FeO chondrules in LEW85332 formed early in nebular history when metal was intimately mixed with silicates in the chondrule precursors, and that the viscosity of the liquid-solid mix was too high to permit expulsion of the metal by centrifugal action; their porphyritic structures are consistent with incomplete melting, which would result in relatively high viscosities. When the high FeO chondrules formed somewhat later, much of the Fe was oxidized and the melting of precursors was more extensive, FeO and other oxidized siderophiles were retained in the silicate liquid, and metal was lost, possibly expelled from low viscosity chondrule melts. The O isotopic compositions of the chondrules form a linear array of slope 0.93 +/- 0.05 on a three-isotope diagram, parallel to the carbonaceous chondrite anhydrous minerals (CCAM) line and a CR chondrule array, but offset from the latter by -1% in (delta)O-18. Some or all of this offset may reflect incorporation of O from Antarctic water during weathering. Chondrule (Delta)O-17 values correlate positively with FeO, possibly indicating that the (Delta)O-17 of the nebular gas composition increased with time. The chemical and O isotopic

  15. Rhenium-osmium systematics of calcium-aluminium-rich inclusions in carbonaceous chondrites

    USGS Publications Warehouse

    Becker, H.; Morgan, J.W.; Walker, R.J.; MacPherson, G.J.; Grossman, J.N.

    2001-01-01

    pose several difficulties. The narrow range of 187Os/188Os in group I, III, V, and VI bulk CAIs, and the agreement with 187Os/188Os of whole rock carbonaceous chondrites suggest that on a bulk inclusion scale, secondary alteration only modestly fractionated Re/Os in these CAIs. The average of 187Os/188Os for group I, III, V, and VI CAIs is indistinguishable from average CI chondrites, indicating a modern solar system value for 187Os/188Os of 0.12650, corresponding to a 187Re/188Os of 0.3964. Copyright ?? 2001 Elsevier Science Ltd.

  16. Aqueous Alteration of Carbonaceous Chondrites: New Insights from Comparative Studies of Two Unbrecciated CM2 Chondrites, Y 791198 and ALH 81002

    NASA Technical Reports Server (NTRS)

    Chizmadia, L. J.; Brearley, A. J.

    2004-01-01

    Carbonaceous chondrites are an important resource for understanding the physical and chemical conditions in the early solar system. In particular, a long-standing question concerns the role of water in the cosmochemical evolution of carbonaceous chondrites. It is well established that extensive hydration of primary nebular phases occurred in the CM and CI chondrites, but the location where this alteration occurred remains controversial. In the CM2 chondrites, hydration formed secondary phases such as serpentine, tochilinite, pentlandite, carbonate and PCP. There are several textural observations which suggest that alteration occurred before the accretion of the final CM parent asteroid, i.e. preaccretionary alteration. Conversely, there is a significant body of evidence that supports parent-body alteration. In order to test these two competing hypotheses further, we studied two CM chondrites, Y-791198 and ALH81002, two meteorites that exhibit widely differing degrees of aqueous alteration. In addition, both meteorites have primary accretionary textures, i.e. experienced minimal asteroidal brecciation. Brecciation significantly complicates the task of unraveling alteration histories, mixing components that have been altered to different degrees from different locations on the same asteroidal parent body. Alteration in Y-791198 is mostly confined to chondrule mesostases, FeNi metal and fine-grained matrix and rims. In comparison, the primary chondrule silicates in ALH81002 have undergone extensive replacement by secondary hydrous phases. This study focuses on compositional and textural relationships between chondrule mesostasis and the associated rim materials. Our hypothesis is: both these components are highly susceptible to aqueous alteration and should be sensitive recorders of the alteration process. For parent body alteration, we expect systematic coupled mineralogical and compositional changes in rims and altered mesostasis, as elemental exchange between these

  17. Xenoliths in the CM2 Carbonaceous Chondrite LON 94101: Implications for Complex Mixing on the Asteroidal Parent Body

    NASA Technical Reports Server (NTRS)

    Lindgren, P.; Lee, M. R.; Sofe, M.; Zolensky, M. E.

    2011-01-01

    Xenoliths are foreign clasts that oc-cur in various classes of meteorites, e.g. [1,2,3]. A re-cent study reveals the presence of several distinct classes of xenoliths in regolith-bearing meteorites, in-cluding in over 20 different carbonaceous chondrites [4]. The most common types of xenoliths are fine-grained hydrous clasts, often referred to as C1 or CI clasts in the literature, although their mineralogy is actually more similar to hydrous micrometeorites [5,6]. Xenoliths in meteorites present an opportunity to study material not yet classified or available as separate meteorites, and can provide additional information on processes in the dynamic early history of the Solar Sys-tem. Here we have performed chemical and mineralogi-cal analyses of xenoliths in the CM2 carbonaceous chondrite LON 94101, using scanning electron micro-scopy (SEM) and transmission electron microscopy (TEM).

  18. Abundances of volatile-bearing phases in carbonaceous chondrites and cooling rates of meteorites based on cation ordering of orthopyroxenes

    NASA Technical Reports Server (NTRS)

    Ganguly, Jibamitra

    1989-01-01

    Results of preliminary calculations of volatile abundances in carbonaceous chondrites are discussed. The method (Ganguly 1982) was refined for the calculation of cooling rate on the basis of cation ordering in orthopyroxenes, and it was applied to the derivation of cooling rates of some stony meteorites. Evaluation of cooling rate is important to the analysis of condensation, accretion, and post-accretionary metamorphic histories of meteorites. The method of orthopyroxene speedometry is widely applicable to meteorites and would be very useful in the understanding of the evolutionary histories of carbonaceous chondrites, especially since the conventional metallographic and fission track methods yield widely different results in many cases. Abstracts are given which summarize the major conclusions of the volatile abundance and cooling rate calculations.

  19. Crystallography of Magnetite Plaquettes and their Significance as Asymmetric Catalysts for the Synthesis of Chiral Organics in Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Chan, Q. H. S.; Zolensky, M. E.

    2015-01-01

    We have previously observed the magnetite plaquettes in carbonaceous chondrites using scanning electron microscope (SEM) imaging, examined the crystal orientation of the polished surfaces of magnetite plaquettes in CI Orgueil using electron backscattered diffraction (EBSD) analysis, and concluded that these magnetite plaquettes are likely naturally asymmetric materials. In this study, we expanded our EBSD observation to other magnetite plaquettes in Orgueil, and further examined the internal structure of these remarkable crystals with the use of X-ray computed microtomography.

  20. Detection of serpentine in exogenic carbonaceous chondrite material on Vesta from Dawn FC data

    NASA Astrophysics Data System (ADS)

    Nathues, Andreas; Hoffmann, Martin; Cloutis, Edward A.; Schäfer, Michael; Reddy, Vishnu; Christensen, Ulrich; Sierks, Holger; Thangjam, Guneshwar Singh; Le Corre, Lucille; Mengel, Kurt; Vincent, Jean-Baptist; Russell, Christopher T.; Prettyman, Tom; Schmedemann, Nico; Kneissl, Thomas; Raymond, Carol; Gutierrez-Marques, Pablo; Hall, Ian; Büttner, Irene

    2014-09-01

    The Dawn mission’s Framing Camera (FC) observed Asteroid (4) Vesta in 2011 and 2012 using seven color filters and one clear filter from different orbits. In the present paper we analyze recalibrated HAMO color cubes (spatial resolution ∼60 m/pixel) with a focus on dark material (DM). We present a definition of highly concentrated DM based on spectral parameters, subsequently map the DM across the Vestan surface, geologically classify DM, study its spectral properties on global and local scales, and finally, compare the FC in-flight color data with laboratory spectra. We have discovered an absorption band centered at 0.72 μm in localities of DM that show the lowest albedo values by using FC data as well as spectral information from Dawn’s imaging spectrometer VIR. Such localities are contained within impact-exposed outcrops on inner crater walls and ejecta material. Comparisons between spectral FC in-flight data, and laboratory spectra of meteorites and mineral mixtures in the wavelength range 0.4-1.0 μm, revealed that the absorption band can be attributed to the mineral serpentine, which is typically present in CM chondrites. Dark material in its purest form is rare on Vesta’s surface and is distributed globally in a non-uniform manner. Our findings confirm the hypothesis of an exogenic origin of the DM by the infall of carbonaceous chondritic material, likely of CM type. It further confirms the hypothesis that most of the DM was deposited by the Veneneia impact.

  1. Thermal alteration in carbonaceous chondrites and implications for sublimation in rock comets

    NASA Astrophysics Data System (ADS)

    Springmann, Alessondra; Lauretta, Dante S.; Steckloff, Jordan K.

    2015-11-01

    Rock comets are small solar system bodies in Sun-skirting orbits (perihelion q < ~0.15 AU) that form comae rich in mineral sublimation products, but lack typical cometary ice sublimation products (H2O, CO2, etc.). B-class asteroid (3200) Phaethon, considered to be the parent body of the Geminid meteor shower, is the only rock comet currently known to periodically eject dust and form a coma. Thermal fracturing or thermal decomposition of surface materials may be driving Phaethon’s cometary activity (Li & Jewitt, 2013). Phaethon-like asteroids have dynamically unstable orbits, and their perihelia can change rapidly over their ~10 Myr lifetimes (de León et al., 2010), raising the possibility that other asteroids may have been rock comets in the past. Here, we propose using spectroscopic observations of mercury (Hg) as a tracer of an asteroid’s thermal metamorphic history, and therefore as a constraint on its minimum achieved perihelion distance.B-class asteroids such as Phaethon have an initial composition similar to aqueously altered primitive meteorites such as CI- or CM-type meteorites (Clark et al., 2010). Laboratory heating experiments of ~mm sized samples of carbonaceous chondrite meteorites from 300K to 1200K at a rate of 15K/minute show mobilization and volatilization of various labile elements at temperatures that could be reached by Mercury-crossing asteroids. Samples became rapidly depleted in labile elements and, in particular, lost ~75% of their Hg content when heated from ~500-700 K, which corresponds to heliocentric distances of ~0.15-0.3 au, consistent with our thermal models. Mercury has strong emission lines in the UV (~ 185 nm) and thus its presence (or absence) relative to carbonaceous chondrite abundances would indicate if these bodies had perihelia in their dynamical histories inside of 0.15 AU, and therefore may have previously been Phaethon-like rock comets. Future space telescopes or balloon-borne observing platforms equipped with a UV

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

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael; Abell, Paul; Tonui, Eric

    2005-01-01

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

  3. Synchrotron Radiation XRD Analysis of Indialite in Y-82094 Ungrouped Carbonaceous Chondrite

    NASA Technical Reports Server (NTRS)

    Mikouchi, T.; Hagiya, K.; Sawa, N.; Kimura, M.; Ohsumi, K.; Komatsu, M.; Zolensky, M.

    2016-01-01

    Y-82094 is an ungrouped type 3.2 carbonaceous chondrite, with abundant chondrules making 78 vol.% of the rock. Among these chondrules, an unusual porphyritic Al-rich magnesian chondrule is reported that consists of a cordierite-like phase, Al-rich orthopyroxene, cristobalite, and spinel surrounded by an anorthitic mesostasis. The reported chemical formula of the cordierite-like phase is Na(0.19)Mg(1.95)Fe(0.02)Al(3.66)Si(5.19)O18, which is close to stoichiometric cordierite (Mg2Al3[AlSi5O18]). Although cordierite can be present in Al-rich chondrules, it has a high temperature polymorph (indialite) and it is therefore necessary to determine whether it is cordierite or indialite in order to better constrain its formation conditions. In this abstract we report on our synchrotron radiation X-ray diffraction (SR-XRD) study of the cordierite-like phase in Y-82094.

  4. Microcraters and solar flare tracks in crystals from carbonaceous chondrites and lunar breccias

    NASA Technical Reports Server (NTRS)

    Goswami, J. N.; Hutcheon, I. D.; Macdougall, J. D.

    1976-01-01

    Results of microcrater and solar-flare track studies of grains from the interiors of five carbonaceous chondrites and one lunar 'soil breccia' are combined to investigate variations in solar flare intensity, variations in micrometeorite particle flux, characteristics of interplanetary submicron particles, and the probable region in space where the precompaction irradiation occurred. The thickness turnover rate, material loss rate, and other parameters of the regolith-like surface where the meteorites must have formed are determined to a certain extent by considering published data on solar-wind and spallogenic species in the meteorites in conjunction with the present data. It is found that: (1) most irradiation features are most plausibly explained in terms of a regolith origin; (2) the shape of the solar-flare energy spectrum has not changed over the last 4.2 billion years; (3) the flux of small micrometeoroids about 4.2 billion years ago cannot have been more than 4 to 20 times higher than the flux today; and (4) parent-body regolith turnover rates were not extremely high.

  5. The paleomagnetic record in carbonaceous chondrites - Natural remanence and magnetic properties

    NASA Technical Reports Server (NTRS)

    Brecher, A.; Arrhenius, G.

    1974-01-01

    Recent results of an intensive study of the natural remanence (NRM) and the magnetic properties of carbonaceous chondrites (CC) are summarized. It is convincingly demonstrated that the record of ancient magnetic fields has been preserved in these least-altered old samples of solar system material known. Intensities of specific NRM in the 13 meteorites surveyed span a broad range of values from 0.00005 to 0.5 emu/g. A low-temperature cleaning technique, based on the memory effect in magnetite grains, was followed by alternating field (af) demagnetization of the residual memory to exhibit the relative stability of NRM in the CC studied. No systematic correlation was found of either intensity or stability of NRM to af demagnetization with petrologic subtype, beyond a trend of increasing stability of memory from petrologic subtype C2 to subtype C4. The intensity and stability behavior of the saturation remanence are better suited for use in a magnetic classification of CC.

  6. The case for vestiges of early solar system biota in carbonaceous chondrites: petroleum geochemical snapshots and possible future petroleum prospects on Mars expedition

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Prasanta K.; Mossman, David J.; Ehrman, James M.

    2007-09-01

    This research documents the analysis and interpretation of selected Carbonaceous Chondrites (CC) including Murchison, Allende, NWA 3003, Dhofar 735, Orgueil, Tagish Lake and Vigarano using organic petrology, scanning electron microscopy, and petroleum geochemistry. The kerogen microstructures and bitumen within CCs closely resemble remnant 2.5 Ga terrestrial microbial-like structures and their biodegraded components and solid bitumen. In both instances, organoclasts are associated with framboidal iron sulfides or oxides and clay-like minerals. The organic-rich kerogens within three CCs (especially Murchison) might have served as petroleum source rocks for the early generation of hydrocarbons. The maturity varies between 0.7% (Orgueil) and 1.24% (Murchison), to 5.1 % Ro (Vigarano) with predicted maturation temperatures of 100° to 475°C. Geochemical analysis of selected CCs (Murchison, Orgueil, and Tagish Lake) reveal the organic richness and the presence of low molecular weight n-alkanes (C 10 to C 20), complex cyclo-and isoalkanes, nonhydrocarbons, elemental sulfur with abundant aromatic compounds, most of them similar to bacterial and algal derived petroleum products. Apart from the concept of panspermia, the data highlights that three CCs sustained a formation temperature (<200°C) capable of supporting bacterial growth in a cooler early Solar System environment. In effect, the information encoded within these extraterrestrial sediments represents a cosmic analogue to terrestrial geopolymers and bitumen that may include some crude oil biomarkers. Therefore, the authors propose a model of a "universal unconventional petroleum system", which implies a prospect of oil and gas within the Martian environment and elsewhere within the Solar System.

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

    NASA Astrophysics Data System (ADS)

    Ruzicka, A.; Boynton, W. V.

    1992-07-01

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

  8. Allende meteorite: a high-voltage electron petrographic study.

    PubMed

    Green, H W; Radcliffe, S V; Heuer, A H

    1971-05-28

    Electron-transparent sections of the Allende meteorite, a carbonaceous chondrite, have been prepared by ion-thinning and examined by high-voltage (800-kilovolt) transmission electron microscopy. The matrix crystals, mainly olivine, range in size from approximately 5 to approximately 0.01 micrometers; carbon is present as intergranular films of poorly crystalline graphite. The chondrules exhibit extensive radiation damage, a feature lacking in the matrix. In addition, both chondrules and matrix are undeformed and contain negative crystals; submicroscopic exsolution lamellae are present in pyroxenes. Comparison of the substructure in the Allende meteorite with that in the Parnallee meteorite and in lunar and selected terrestrial rocks leads to the conclusion that chondrule irradiation preceded cold accretion during formation of the solar system and that the meteorite has since been undisturbed.

  9. Transmission infrared spectra (2-25 μm) of carbonaceous chondrites (CI, CM, CV-CK, CR, C2 ungrouped): Mineralogy, water, and asteroidal processes

    NASA Astrophysics Data System (ADS)

    Beck, P.; Garenne, A.; Quirico, E.; Bonal, L.; Montes-Hernandez, G.; Moynier, F.; Schmitt, B.

    2014-02-01

    In this work, infrared transmission spectra (2-25 μm range, 5000-400 cm-1) of 40 carbonaceous chondrites were analyzed (21 CMs, 5 CVs, 6 CRs, 3 CKs, 3 C2s and 2 CIs). All these meteorite groups are known to have experienced significant aqueous alteration (except the CKs). These IR measurements provide information about the parent body processes experienced, as well as spectra for comparison with observations of Solar System small bodies and possibly with astronomical observations of accretion and debris disks. This study reveals that each meteorite group appears to have specific signatures in the measured IR spectral range. In the case of the CI and CM groups, results show a variability in the shape of the silicate features that can be related to the evolution of the mineralogy with increasing extent of aqueous alteration extent as described by several authors with other techniques. This evolution of the silicate feature can be seen in the variation in the relative intensities of olivine and phyllosilicate IR features. The variability in the silicate features is correlated with the intensity of an -OH related absorption at 3-μm, which can be used for the classification of the meteorites according to the level of hydration. Interestingly, in the case of CM chondrites, for which the mineralogy is expected to be dominated by phyllosilicates (serpentine mostly), the shape of the silicate absorption resembles that of an amorphous silicate, with a broad and symmetric 10-μm band, unlike terrestrial phyllosilicates. The CV and CK groups have IR spectra that are dominated by olivine absorption. From this feature, it is possible to determine average Mg numbers for the olivine. For the CVs, the olivine Mg numbers appear to decrease in the order Kaba-Grosnaja-Vigarano-Mokoia-Allende. This trend is likely related to the long duration of metamorphism experienced by these samples and the chemical re-equilibration between chondritic components. In the case of CK chondrites, the

  10. Application of Scanning-Imaging X-Ray Microscopy to Fluid Inclusion Candidates in Carbonates of Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Tsuchiyama, Akira; Nakano, Tsukasa; Miyake, Akira; Akihisa, Takeuchi; Uesugi, Kentaro; Suzuki, Yoshio; Kitayama, Akira; Matsuno, Junya; Zolensky, Michael E.

    2016-01-01

    In order to search for such fluid inclusions in carbonaceous chondrites, a nondestructive technique using x-ray micro-absorption tomography combined with FIB sampling was developed and applied to a carbonaceous chondrite. They found fluid inclusion candidates in calcite grains, which were formed by aqueous alteration. However, they could not determine whether they are really aqueous fluids or merely voids. Phase and absorption contrast images can be simultaneously obtained in 3D by using scanning-imaging x-ray microscopy (SIXM). In refractive index, n=1-sigma+i(beta), in the real part, 1-sigma is the refractive index with decrement, sigma, which is nearly proportional to the density, and the imaginary part, beta, is the extinction coefficient, which is related to the liner attenuation coefficient, mu. Many phases, including water and organic materials as well as minerals, can be identified by SIXM, and this technique has potential availability for Hayabusa-2 sample analysis too. In this study, we examined quantitative performance of d and m values and the spatial resolution in SIXM by using standard materials, and applied this technique to carbonaceous chondrite samples. We used POM ([CH2O]n), silicon, quartz, forsterite, corundum, magnetite and nickel as standard materials for examining the sigma and mu values. A fluid inclusion in terrestrial quartz and bi-valve shell (Atrina vexillum), which are composed of calcite and organic layers with different thickness, were also used for examining the spatial resolution. The Ivuna (CI) and Sutter's Mill (CM) meteorites were used as carbonaceous chondrite samples. Rod- or cube-shaped samples 20-30 micron in size were extracted by using FIB from cross-sectional surfaces of the standard materials or polished thin sections of the chondrites, which was previously observed with SEM. Then, the sample was attached to a thin W-needle and imaged by SIXM system at beamline BL47XU, SPring-8, Japan. The slice thickness was 109.3 nm

  11. Magnetite as Possible Template for the Synthesis of Chiral Organics in Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Chan, Q. H. S.; Zolensky, M. E.

    2014-01-01

    The main goal of the Japanese Aerospace Ex-ploration Agency (JAXA) Hayabusa-2 mission is to visit and return to Earth samples of a C-type asteroid (162173) 1999 JU3 in order to understand the origin and nature of organic materials in the Solar System. Life on Earth shows preference towards the set of organics with particular spatial arrangements, this 'selectivity' is a crucial criterion for life. With only rare exceptions, life 'determines' to use the left- (L-) form over the right- (D-) form of amino acids, resulting in a L-enantiomeric excess (ee). Recent studies have shown that L-ee is found within the alpha-methyl amino acids in meteorites [1, 2], which are amino acids with rare terrestrial occurrence, and thus point towards a plausible abiotic origin for ee. One of the proposed origins of chiral asymmetry of amino acids in meteorites is their formation with the presence of asymmetric catalysts [3]. The catalytic mineral grains acted as a surface at which nebular gases (CO, H2 and NH3) were allowed to condense and react through Fisher Tropsch type (FTT) syntheses to form the organics observed in meteorites [4]. Magnetite is shown to be an effective catalyst of the synthesis of amino acids that are commonly found in meteorites [5]. It has also taken the form as spiral magnetites (a.k.a. 'plaquettes'), which were found in various carbonaceous chondrites (CCs), including C2s Tagish Lake and Esseibi, CI Orgueil, and CR chondrites [e.g., 6, 7, 8]. In addition, L-ee for amino acids are common in the aqueously altered CCs, as opposed to the unaltered CCs [1]. It seems possible that the synthesis of amino acids with chiral preferences is correlated to the alteration process experienced by the asteroid parent body, and related to the configuration of spiral magnetite catalysts. Since C-type asteroids are considered to be enriched in organic matter, and the spectral data of 1999 JU3 indicates a certain de-gree of aqueous alteration [9], the Hayabusa-2 mission serves as

  12. Elemental Analysis of Carbonaceous Chondrites by Sector Field ICP-MS

    NASA Astrophysics Data System (ADS)

    Braukmüller, N.; Escoube, R.; Münker, C.; Heuser, A.; Wombacher, F.

    2016-08-01

    CM chondrites are analyzed via SF-ICP MS for a comparison of the chemical compositions of antarctic and non-antarctic CM chondrites. Aliquots of Murchison CM2 chondrite powder have been heated in a tube furnace to study the loss of volatile elements.

  13. Bidirectional reflectance spectroscopy of carbonaceous chondrites: Implications for water quantification and primary composition

    NASA Astrophysics Data System (ADS)

    Garenne, A.; Beck, P.; Montes-Hernandez, G.; Brissaud, O.; Schmitt, B.; Quirico, E.; Bonal, L.; Beck, C.; Howard, K. T.

    2016-01-01

    In this study, we measured bidirectional reflectance spectra (0.5-4.0 μm) of 24 CMs, five CRs, one CI, one CV, and one C2 carbonaceous chondrites. These meteorites are known to have experienced an important variability in their relative degrees of aqueous alteration degree (Rubin et al. [2007]. Geochim. Cosmochim. Acta 71, 2361-2382; Howard et al. [2009]. Geochim. Cosmochim. Acta 73, 4576-4589; Howard et al. [2011]. Geochim. Cosmochim. Acta 75, 2735-2751; Alexander et al. [2013]. Geochim. Cosmochim. Acta 123, 244-260). These measurements were performed on meteorite powders inside an environmental cell under a primary vacuum and heated at 60 °C in order to minimize adsorbed terrestrial water. This protocol allows controlling of atmospheric conditions (i.e. humidity) in order to avoid contamination by terrestrial water. We discuss various spectral metrics (e.g. reflectance, band depth, single-scattering albedo, …) in the light of recent bulk composition characterization (Howard et al. [2009]. Geochim. Cosmochim. Acta 73, 4576-4589; Howard et al. [2015]. Geochim. Cosmochim. Acta 149, 206-222; Alexander et al. [2012]. Science 337, 721; Beck et al. [2014]. Icarus 229, 263-277; Garenne et al. [2014]. Geochim. Cosmochim. Acta 137, 93-112). This study reveals variability of reflectance among meteorite groups. The reflectance is not correlated with carbon or hydrogen abundance neither with measured grain size distribution. We suggest that it is rather controlled by the nature of accreted components, in particular the initial matrix/chondrule proportion. Band depth, integrated band depth, mean optical path length, normalized optical path length, effective single-particle absorption thickness were calculated on the so called 3-μm band for reflectance spectra and for single scattering albedo spectra. They were compared with hydrated phase proportions from previous study on the same meteorites by thermogravimetric analyses and infrared spectroscopy in transmission. We find

  14. The amino acid composition of the Sutter's Mill CM2 carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Burton, Aaron S.; Glavin, Daniel P.; Elsila, Jamie E.; Dworkin, Jason P.; Jenniskens, Peter; Yin, Qing-Zhu

    2014-11-01

    We determined the abundances and enantiomeric compositions of amino acids in Sutter's Mill fragment #2 (designated SM2) recovered prior to heavy rains that fell April 25-26, 2012, and two other meteorite fragments, SM12 and SM51, that were recovered postrain. We also determined the abundance, enantiomeric, and isotopic compositions of amino acids in soil from the recovery site of fragment SM51. The three meteorite stones experienced terrestrial amino acid contamination, as evidenced by the low D/L ratios of several proteinogenic amino acids. The D/L ratios were higher in SM2 than in SM12 and SM51, consistent with rain introducing additional L-amino acid contaminants to SM12 and SM51. Higher percentages of glycine, β-alanine, and γ-amino-n-butyric acid were observed in free form in SM2 and SM51 compared with the soil, suggesting that these free amino acids may be indigenous. Trace levels of D+L-β-aminoisobutyric acid (β-AIB) observed in all three meteorites are not easily explained as terrestrial contamination, as β-AIB is rare on Earth and was not detected in the soil. Bulk carbon and nitrogen and isotopic ratios of the SM samples and the soil also indicate terrestrial contamination, as does compound-specific isotopic analysis of the amino acids in the soil. The amino acid abundances in SM2, the most pristine SM meteorite analyzed here, are approximately 20-fold lower than in the Murchison CM2 carbonaceous chondrite. This may be due to thermal metamorphism in the Sutter's Mill parent body at temperatures greater than observed for other aqueously altered CM2 meteorites.

  15. New Titanium Isotope Data for Allende and Efremovka CAIs

    NASA Astrophysics Data System (ADS)

    Leya, Ingo; Schönbächler, Maria; Krähenbühl, Urs; Halliday, Alex N.

    2009-09-01

    We measured the titanium (Ti) isotope composition, i.e., 50Ti/47Ti, 48Ti/47Ti, and 46Ti/47Ti, in five calcium-rich-aluminum-rich refractory inclusions (CAIs) from the oxidized CV3 chondrite Allende and in two CAIs from the reduced CV3 chondrite Efremovka. Our data indicate that CAIs are enriched in 50Ti/47Ti and 46Ti/47Ti and are slightly depleted in 48Ti/47Ti compared to normal Ti defined by ordinary chondrites, eucrites, ureilites, mesosiderites, Earth, Moon, and Mars. Some CAIs have an additional 50Ti excess of ~8ɛ relative to bulk carbonaceous chondrites, which are enriched in 50Ti by ~2ɛ relative to terrestrial values, leading to a total excess of ~10ɛ. This additional 50Ti excess is correlated with nucleosynthetic anomalies found in 62Ni and 96Zr, all indicating an origin from a neutron-rich stellar source. Bulk carbonaceous chondrites show a similar trend, however, the extent of the anomalies is either less than or similar to the smallest anomalies seen in CAIs. Mass balance calculations suggest that bulk Allende Ti possibly consists of a mixture of at least two Ti components, anomalous Ti located in CAIs and a normal component possibly for matrix and chondrules. This argues for a heterogeneous distribution of Ti isotopes in the solar system. The finding that anomalous Ti is concentrated in CAIs suggests that CAIs formed in a specific region of the solar system and were, after their formation, not homogeneously redistributed within the solar system. Combining the CAI data with improved model predictions for early solar system irradiation effects indicates that a local production scenario for the relatively short lived radionuclides can be excluded, because the production of, e.g., 10Be, 26Al, and 41Ca, would result in a significant collateral shift in Ti isotopes, which is not seen in the measured data.

  16. Siderophile-element Anomalies in CK Carbonaceous Chondrites: Implications for Parent-body Aqueous Alteration and Terrestrial Weathering of Sulfides

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

    CK chondrites constitute the most oxidized anhydrous carbonaceous chondrite group; most of the Fe occurs in magnetite and in FeO-rich mafic silicates. The two observed CK falls (Karoonda and Kobe), along with thirteen relatively unweathered CK finds, have unfractionated siderophile-element abundance patterns. In contrast, a sizable fraction of CK finds (9 of 24 investigated) shows fractionated siderophile abundance patterns including low abundances of Ni, Co, Se and Au; the most extreme depletions are in Ni (0.24 of normal CK) and Au (0.14 of normal CK). This depletion pattern has not been found in other chondrite groups. Out of the 74 CK chondrites listed in the Meteoritical Bulletin Database (2006; excluded considerably paired specimens; see http://tin.er.usgs.gov/meteor/ metbull.php) we analyzed 24 and subclassified the CK chondrites in terms of their chemical composition and sulfide mineralogy: sL (siderophiles low; six samples) for large depletions in Ni, Co, Se and Au (>50% of sulfides lost); sM (siderophiles medium; two CKs) for moderately low Ni and Co abundances (sulfides are highly altered or partly lost); sH (siderophiles high; one specimen) for enrichments in Ni, Co, Se and Au; 'normal' for unfractionated samples (13 samples). The sole sH sample may have obtained additional sulfide from impact redistribution in the parent asteroid. We infer that these elements became incorporated into sulfides after asteroidal aqueous processes oxidized nebular metal; thermal metamorphism probably also played a role in their mineral siting. The siderophile losses in the SL and sM samples are mainly the result of oxidation of pentlandite, pyrite and violarite by terrestrial alteration followed by leaching of the resulting phases. Some Antarctic CK chondrites have lost most of their sulfides but retained Ni, Co, Se and Au, presumably as insoluble weathering products.

  17. Formation, Chemistry and Fertility of Extraterrestrial Soils: Cohesion, Water Adsorption and Surface Area of Carbonaceous Chondrite. Prebiotic and Space Resource Applications

    NASA Astrophysics Data System (ADS)

    Mautner, Michael N.

    1999-01-01

    Following microbial and plant responses to Murchison CM2 meteorite nutrients, further soil fertility parameters are examined. Cohesion of the matrix is tested by dissolving in acidic disaggregation agents, 0.4 M CH3COOH, 10% HNO3, H2SO4(pH 3), 50%H2O2+H2SO4(pH 3), and saturated CO2solution. The responses suggest that carbonates and the organic polymer contribute as cementing agents, and that enhanced disaggregation by H2O2and diminished disaggregation in saturated CO2solutions may contribute to the weathering of carbonaceous meteorites in martian or early Earth environments, respectively. The cation exchange capacities (CEC) of the solid (7.2±0.8 meq/100 g) and powdered Murchison (7.8±1.5 meq/100 g) are comparable. The cation exchange capacity is not reduced by oxidation or acetylation, suggesting that the binding sites of exchangeable cations are mostly inorganic. The CEC correlates with water vapor adsorption similar to that for terrestrial soils. For example, at 20°C andP(H2O)=10.8 mbars, 17 mg/g H2O is adsorbed on Murchison (CEC=7.2 meq/100 g) and only 0.6 mg/g on Allende (CEC=0.4 meq/100 g). Under these conditions 13 H2O molecules are adsorbed per surface cation in Murchison and 8 H2O molecules/cation in Allende, similar to 9 H2O molecules/cation in terrestrial soils and in montmorillonite. Adsorption isotherms on the Murchison are convex at low pressures, indicating strong bonding of the first water molecules, and concave at high pressures, indicating a broad pore size distribution. Isotherms at 278, 293, and 311 K yield isosteric heat of adsorption of 56.5±2.5 kJ/mol at 4-8 H2Oadsorbedmolecules/cation, similar to that for montmorillonite. The isotherms yield a specific surface area of Sw=37×103m2/kg for Murchison, larger than the 19×103m2/kg of pure serpentine, suggesting contributions, in addition to the main serpentine-like phyllosilicates, by components equivalent to a 9-12% smectic clay-like content. Water evaporation curves from meteorite surfaces

  18. Element Distribution in Allende Determined by LA-ICP-MS

    NASA Astrophysics Data System (ADS)

    Wombacher, F.; Funk, C.; Frick, D. A.; Koch, J.; Günther, D.

    2016-08-01

    A novel LA-ICP-MS method has been developed in order to evaluate elemental distributions of 26 major and trace elements in chondritic meteorites. A reconnaissance study on a section from the Allende chondrite is presented.

  19. Characterising the CI and CI-like carbonaceous chondrites using thermogravimetric analysis and infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    King, Ashley J.; Solomon, Jake R.; Schofield, Paul F.; Russell, Sara S.

    2015-12-01

    The CI and CI-like chondrites provide a record of aqueous alteration in the early solar system. However, the CI-like chondrites differ in having also experienced a late stage period of thermal metamorphism. In order to constrain the nature and extent of the aqueous and thermal alteration, we have investigated the bulk mineralogy and abundance of H2O in the CI and CI-like chondrites using thermogravimetric analysis and infrared spectroscopy.

  20. Quantified, whole section trace element mapping of carbonaceous chondrites by Synchrotron X-ray Fluorescence Microscopy: 1. CV meteorites

    NASA Astrophysics Data System (ADS)

    Dyl, Kathryn A.; Cleverley, James S.; Bland, Phil A.; Ryan, Chris G.; Fisher, Louise A.; Hough, Robert M.

    2014-06-01

    We present the application of a new synchrotron-based technique for rapid mapping of trace element distributions across large areas of the CV3 meteorites Allende and Vigarano. This technique utilizes the Australian Synchrotron X-ray Fluorescence Microscopy (XFM) beam line with its custom designed and built X-ray detector array called Maia. XFM with Maia allows data to be collected using a 2 μm spot size at very low dwell times (∼0.1-0.5 ms), resulting in maps of entire thin sections in ∼5 h. Maia is an energy dispersive detector system with a large collection solid-angle, which allows full spectral acquisition and high sensitivity. Hence, there is no need to constrain the elements of interest a priori. We collected whole section maps (∼2 cm × 1 cm) from 3 thick sections of Allende and a single map (2 cm × 1.5 cm) from a thick section of Vigarano. Our experimental conditions provide data for elements with 20 ⩽ Z ⩽ 40 (K-shell, Ca through Zr) and the L-emissions of Os, Ir, Pt, Au, and Pb. We illustrate the unique capabilities of this technique by presenting observations across myriad length scales, from the centimeter-scale down to the detection of sub-micrometer particles within these objects. Our initial results show the potential of this technique to help decipher spatial and textural variations in trace element chemistry between CAIs, chondrules, matrix, and other chondritic components. We also illustrate how these datasets can be applied to understanding both nebular and parent-body processes within meteorites.

  1. The formation and alteration of the Renazzo-like carbonaceous chondrites III: Toward understanding the genesis of ferromagnesian chondrules

    NASA Astrophysics Data System (ADS)

    Schrader, Devin L.; Connolly, Harold C.; Lauretta, Dante S.; Zega, Thomas J.; Davidson, Jemma; Domanik, Kenneth J.

    2015-01-01

    To better understand the formation conditions of ferromagnesian chondrules from the Renazzo-like carbonaceous (CR) chondrites, a systematic study of 210 chondrules from 15 CR chondrites was conducted. The texture and composition of silicate and opaque minerals from each observed FeO-rich (type II) chondrule, and a representative number of FeO-poor (type I) chondrules, were studied to build a substantial and self-consistent data set. The average abundances and standard deviations of Cr2O3 in FeO-rich olivine phenocrysts are consistent with previous work that the CR chondrites are among the least thermally altered samples from the early solar system. Type II chondrules from the CR chondrites formed under highly variable conditions (e.g., precursor composition, redox conditions, cooling rate), with each chondrule recording a distinct igneous history. The opaque minerals within type II chondrules are consistent with formation during chondrule melting and cooling, starting as S- and Ni-rich liquids at 988-1350 °C, then cooling to form monosulfide solid solution (mss) that crystallized around olivine/pyroxene phenocrysts. During cooling, Fe,Ni-metal crystallized from the S- and Ni-rich liquid, and upon further cooling mss decomposed into pentlandite and pyrrhotite, with pentlandite exsolving from mss at 400-600 °C. The composition, texture, and inferred formation temperature of pentlandite within chondrules studied here is inconsistent with formation via aqueous alteration. However, some opaque minerals (Fe,Ni-metal versus magnetite and panethite) present in type II chondrules are a proxy for the degree of whole-rock aqueous alteration. The texture and composition of sulfide-bearing opaque minerals in Graves Nunataks 06100 and Grosvenor Mountains 03116 suggest that they are the most thermally altered CR chondrites.

  2. Mineral associations and character of isotopically anomalous organic material in the Tagish Lake carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Zega, Thomas J.; Alexander, Conel M. O.'D.; Busemann, Henner; Nittler, Larry R.; Hoppe, Peter; Stroud, Rhonda M.; Young, Andrea F.

    2010-10-01

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

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

    SciTech Connect

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

    2010-01-01

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

  4. Hydrothermal venting on carbonaceous chondritic elevations on 1 Ceres and 4 Vesta

    NASA Astrophysics Data System (ADS)

    Hoffmann, Martin; Nathues, Andreas; Platz, Thomas; Thangjam, Guneshwar

    2016-04-01

    Framing Camera images of the Dawn spacecraft [1] led to the discovery of recent geologic activity on Ceres, including deposition of salts, formation of near surface haze [2], and impact associated spectral diversity. More detailed analyses revealed widespread flow features, partly composed of granular material, but also indicating sites of fluidized areas of the surface and sub-surface. The unexpected discovery of deposits of carbonaceous chondritic material on Vesta associated with indications of considerable amounts of volatiles at large impact structures hint at similar processes [3, 4]. Near large crater walls on both proto-/dwarf-planets, montes and domes appear to be associated with uplift and even release of water-driven material including salts and clays [5, 6]. We report morphologic and color band spectroscopic characteristics of selected key features on 1 Ceres and 4 Vesta which demonstrate this context. A first analysis indicates compositional differences of the proportion of the content of salts and phyllosilicates, e. g. on the different elevations of the primary and secondary spots in Occator and some flow features. The distribution and diversity of these color features is further characterized by a comparison with more widespread properties on the whole surface. During this investigation, not only the link between salt deposits and different types of materials at the centers of activity could be described, but we also offer an intriguing new interpretation of one of the most prominent surface features of Vesta: Lucaria Tholus. Several analogies with similar features and properties of Mars [7] further support the view of a related origin. References: [1] Sierks, H. et al., Space Sci. Rev., 163, 263-327, 2011. [2] Nathues, A. et al., Nature 528, 237-240, 2015. [3] Reddy, V. et al. Icarus, 221, 544-559, 2012. [4] Scully, J. E. C. et al., EPSC Abstracts 8, 2013-242-2, 2013. [5] Platz, T. et al. LPSC 2016 [6] Ruesch, O. et al. LPSC 2016 [7] Platz, T. et

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

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

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

  6. 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.

  7. Comparison of Nickel XANES Spectra and Elemental Maps from a Ureilite, a LL3.8 Ordinary Chondrite, Two Carbonaceous Chondrites and Two Large Cluster IDPs

    NASA Technical Reports Server (NTRS)

    Wirick, S.; Flynn, G. J.; Sutton, S.; Zolensky, M. E.

    2014-01-01

    Nickel in the extraterrestrial world is commonly found in both Fe-Ni sulfide and Fe-Ni met-al forms [1] and in the pure metal state in the interior of iron meteorites where it is not easily oxidized. Ni is also found in olivine, pyroxene and glasses and in some melts the partitioning of Ni between the olivines and glass is controlled by the amount of S in the melt [2]. Its most common valence state is Ni(2+) but Ni also occurs as Ni(0), Ni(+), and Ni(3+) and rarely as Ni(2-), Ni(1-) and Ni(4+) [3]. It's valence state in olivines is Ni(2+) in octa-hedral coordination on the M1 site and rarely on the M2 site.[4]. The chemical sensitivity of X-ray absorp-tion near-edge structure (XANES) spectroscopy is well established and can be used to determine not only va-lence states but also coordination sites [5]. We report here Ni XANES spectroscopy and elemental maps collected from 2 carbonaceous chondrites, 2 large clus-ter IDPs, 1 ureilite and 1 LL3 orginary chondrite.Using XANES it may be possible to find a common trait in the large cluster IDPs that will also be found in mete-orite samples.

  8. Matrix and whole-rock fractionations in the Acfer 094 type 3.0 ungrouped carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Wasson, John T.; Rubin, Alan E.

    2010-01-01

    We used the electron microprobe to study matrix in the ungrouped type 3.0 carbonaceous chondrite Acfer 094 using 7×7-point, focused-beam arrays; data points attributable to mineral clasts were discarded. The grid areas show resolvable differences in composition, but differences are less pronounced than we observed in studies of CR2 LaPaz Icefield (LAP) 02342 (Wasson and Rubin [2009]) and CO3.0 Allan Hills A77307 (Brearley [1993]). A key question is why Acfer shows an anomalously uniform composition of matrix compared with these other carbonaceous chondrites. Both whole-rock and matrix samples of Acfer 094 show enhancements of Ca and K; it appears that these reflect contamination during hot desert weathering. By contrast, the whole-rock abundance of Na is low. Although weathering effects are responsible for some fractionations, it appears that nebular effects are also resolvable in matrix compositions in Acfer 094. As with LAP 02342, we infer that the observed differences among different areas were inherited from the solar nebula and may have been carried by porous chondrules that experienced low (about 20%) degrees of melting. Acfer 094 has been comminuted by one or more impact events that may also have caused volatile loss. Thus, despite preserving evidence (e.g., an exceptionally high content of presolar SiC) implying a high degree of pristinity, Acfer 094 is far from pristine in other respects. This evidence of comminution and an O-isotopic composition similar to values measured in metamorphosed CM chondrites suggest that Acfer was hydrated before being outgassed by the inferred impact event. Convection within the plume associated with the impact event probably also contributed to the homogenization of the Acfer 094 matrix.

  9. 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.

  10. Isotopically uniform, 16O-depleted calcium, aluminum-rich inclusions in CH and CB carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Krot, Alexander N.; Nagashima, Kazuhide; Petaev, Michail I.

    2012-04-01

    In situ oxygen-isotope measurements of calcium-aluminum-rich inclusions (CAIs) from the metal-rich carbonaceous chondrites Isheyevo (CH/CB-like), Acfer 214 paired with Acfer 182 (CH), QUE 94411 paired with QUE 94627 (CBb), and Hammadah al Hamra 237 (CBb) revealed the presence of a common population of igneous, isotopically uniform, 16O-depleted inclusions: Δ17O (average ± 2 standard deviations) = -7 ± 4‰, -6 ± 5‰, and -8 ± 3‰, respectively. All CAIs from CBs and a significant fraction of those from CHs and Isheyevo are 16O-depleted. Most of the 16O-depleted CAIs consist of Ti-poor Al-diopside, spinel, melilite, and forsterite and surrounded by a single- and double-layered rim of forsterite ± diopside. The 16O-depleted CAIs composed of hibonite, grossite, melilite, and spinel, and surrounded by the multilayered melilite + diopside ± forsterite rims are less common. Some of the 16O-depleted refractory igneous inclusions composed of Al-diopside, forsterite, and ±spinel have chondrule-like textures (skeletal or barred). They are mineralogically most similar to Al-diopside-rich chondrules found in metal-rich carbonaceous chondrites and composed of Al-diopside, forsterite, Al-rich low-Ca pyroxene, ±glassy mesostasis, and ±spinel, suggesting there is a continuum between these objects. We suggest that (i) most of the isotopically uniform and 16O-depleted CAIs resulted from remelting of pre-existing, possibly 16O-rich refractory inclusions. The remelting may have occurred during formation of the magnesian, non-porphyritic (cryptocrystalline and skeletal) chondrules in CHs, CBs, and Isheyevo either by an unspecified, late, single-stage, highly-energetic event or in an impact-generated plume previously hypothesized for their origin; both mechanisms probably occurred in the solar nebula (i.e., in the presence of the nebula gas). The forsterite ± pyroxene rims around 16O-depleted CAIs may have resulted from evaporation-recondensation of silicon and magnesium

  11. On the Behavior of Phosphorus During the Aqueous Alteration of CM2 Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Brearley, Adrian J.; Chizmadia, Lysa J.

    2005-01-01

    During the earliest period of solar system formation, water played an important role in the evolution of primitive dust, both after accretion of planetesimals and possible before accretion within the protoplanetary disk. Many chondrites show evidence of variable degrees of aqueous alteration, the CM2 chondrites being among the most studied [1]. This group of chondrites is characterized by mineral assemblages of both primary and secondary alteration phases. Hence, these meteorites retain a particularly important record of the reactions that occurred between primary high temperature nebular phases and water. Studies of these chondrites can provide information on the conditions and environments of aqueous alteration and the mobility of elements during alteration. This latter question is at the core of a debate concerning the location of aqueous alteration, i.e. whether alteration occurred predominantly within a closed system after accretion (parent body alteration) or whether some degree of alteration occurred within the solar nebula or on ephemeral protoplanetary bodies prior to accretion. At the core of the parent body alteration model is the hypothesis that elemental exchange between different components, principally chondrules and matrix, must have occurred. chondrules and matrix, must have occurred. In this study, we focus on the behavior of the minor element, phosphorus. This study was stimulated by observations of the behavior of P during the earliest stages of alteration in glassy mesostasis in type II chondrules in CR chondrites and extends the preliminary observations of on Y791198 to other CM chondrites.

  12. The appearance of Carbonaceous Chondrites on (1) Ceres from observations by the Dawn Framing Camera

    NASA Astrophysics Data System (ADS)

    Schäfer, Tanja; Schäfer, Michael; Mengel, Kurt; Cloutis, Edward A.; Izawa, Matthew R. M.; Thangjam, Guneshwar; Hoffmann, Martin; Platz, Thomas; Nathues, Andreas; Kallisch, Jan; Ripken, Joachim; Russel, Christopher T.

    2016-04-01

    NASA's Dawn spacecraft reached dwarf planet Ceres in March 2015 and started data acquisition using three different instruments. These are the Framing Camera (FC; [1]), the Visible & Infrared Spectrometer (VIR; [2]), and the Gamma Ray and Neutron Detector (GRaND; [3]). In our work we focus on the potential appearance of carbonaceous chondritic (CC) material on the cerean surface using Dawn FC color mosaics covering the VIS/NIR wavelength region. In preparation of the Dawn arrival at Ceres, a discrimination scheme for CC groups using FC color ratios was developed by [4] and is based on 121 CC laboratory spectra compiled from RELAB. As the cerean surface material mainly differs by its spectral slope over the whole FC wavelength range (0.44-0.97 μm), we classified the color mosaics by this parameter. We applied the CC discrimination scheme only to those regions on the cerean surface (more than 90 %) which exhibit spectral slopes ≥ -1 % reflectance per μm to exclude the strongly negative sloped regions of large young craters such as Occator, Haulani, and Oxo. These are not likely to be similar to pure CC material as can be seen by their brightness and their bluish spectral slope [5]. We found that the surface material of Ceres is, among the suite of CCs, most similar to Ivuna samples artificially heated to 200 and 300°C [6] and unusual CCs, which naturally experienced heating. The latter ones comprise Dhofar 225, Y-86789 and Y-82162, which have been determined to have undergone aqueous alteration and subsequent thermal metamorphism (e.g. [7,8]).Our comparison with VIR data shows, that the spectra of Ivuna heated to 200°C and 300°C match well the OH-absorption at 2.7 μm but do not show the smaller 3.05-3.1 μm absorption observed on Ceres [9,10,11]. Nevertheless, the remarkably flat UV drop-off detected on the cerean surface may, at least spectrally, correspond to highly aqueously altered and subsequently thermally metamorphosed CC material. Further alteration of

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  14. Determination of sulphur-bearing components in C1 and C2 carbonaceous chondrites by stepped combustion

    NASA Astrophysics Data System (ADS)

    Burgess, R.; Wright, I. P.; Pillinger, C. T.

    1991-03-01

    Ten type 1 and 2 carbonaceous chondrites have been analyzed by stepped combustion to determine the nature of their sulphur-bearing components. All samples show complex release patterns which, when combined with published petrographic observations, can be interpreted in terms of sulphur derived from a mixture of at least seven components (elemental sulphur, organic sulphur, sulphide, FESON or tochilinite, and sulphates: gypsum, bloedite and epsomite). Estimated concentrations of individual components show that most of the sulphur in the meteorites exists in oxidized form. The concentrations of reduced and oxidized components can be used to derive approximate oxidized/reduced sulphur ratios for the meteorites. These ratios are indicators of the extent of aqueous alteration and increase in the order CM less than CI. Formation of the different alteration products by aqueous processes active on the meteorite parent body appears to be the most likely origin.

  15. Early solar system. Early accretion of water in the inner solar system from a carbonaceous chondrite-like source.

    PubMed

    Sarafian, Adam R; Nielsen, Sune G; Marschall, Horst R; McCubbin, Francis M; Monteleone, Brian D

    2014-10-31

    Determining the origin of water and the timing of its accretion within the inner solar system is important for understanding the dynamics of planet formation. The timing of water accretion to the inner solar system also has implications for how and when life emerged on Earth. We report in situ measurements of the hydrogen isotopic composition of the mineral apatite in eucrite meteorites, whose parent body is the main-belt asteroid 4 Vesta. These measurements sample one of the oldest hydrogen reservoirs in the solar system and show that Vesta contains the same hydrogen isotopic composition as that of carbonaceous chondrites. Taking into account the old ages of eucrite meteorites and their similarity to Earth's isotopic ratios of hydrogen, carbon, and nitrogen, we demonstrate that these volatiles could have been added early to Earth, rather than gained during a late accretion event. PMID:25359971

  16. Early solar system. Early accretion of water in the inner solar system from a carbonaceous chondrite-like source.

    PubMed

    Sarafian, Adam R; Nielsen, Sune G; Marschall, Horst R; McCubbin, Francis M; Monteleone, Brian D

    2014-10-31

    Determining the origin of water and the timing of its accretion within the inner solar system is important for understanding the dynamics of planet formation. The timing of water accretion to the inner solar system also has implications for how and when life emerged on Earth. We report in situ measurements of the hydrogen isotopic composition of the mineral apatite in eucrite meteorites, whose parent body is the main-belt asteroid 4 Vesta. These measurements sample one of the oldest hydrogen reservoirs in the solar system and show that Vesta contains the same hydrogen isotopic composition as that of carbonaceous chondrites. Taking into account the old ages of eucrite meteorites and their similarity to Earth's isotopic ratios of hydrogen, carbon, and nitrogen, we demonstrate that these volatiles could have been added early to Earth, rather than gained during a late accretion event.

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

    NASA Technical Reports Server (NTRS)

    Kerridge, J. F.

    1983-01-01

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

  18. Lunar sample analysis. [Allende meteorite

    NASA Technical Reports Server (NTRS)

    Housley, R. M.

    1985-01-01

    Recent results on the antarctic meteorite ALPHA 77003 which contribute to understanding the alteration processes which produced matrix in unequilibrated chondrites are presented. Also included are additional scanning electron microscope results confirming that the matrix in Allende was formed by in situ alteration.

  19. The petrography, mineralogy and origins of calcium sulphate within the Cold Bokkeveld CM carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Lee, M. R.

    1993-03-01

    A detailed scanning and transmission electron microscopy study was carried out on the Cold Bokkeveld chondrite. Fracture-filling calcium sulphate, calcium sulphate within calcitized chondrules and within the matrix calcite was examined. Results indicate that calcium sulphate is widespread and the majority of its crystals are fibrous. The calcium sulphate is composed of a fine-scale structure of hemihydrate and anhydrate which may have been formed by dehydration of primary gypsum during sample preparation. The timing and origin of aqueous solutions and alteration of the chondrite are discussed and possible links with CI meteorites are considered.

  20. 53Mn-53Cr dating of aqueously formed carbonates in the CM2 lithology of the Sutter's Mill carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Jilly, Christine E.; Huss, Gary R.; Krot, Alexander N.; Nagashima, Kazuhide; Yin, Qing-Zhu; Sugiura, Naoji

    2014-11-01

    Radiometric dating of secondary minerals can be used to constrain the timing of aqueous alteration on meteoritic parent bodies. Dolomite is a well-documented secondary mineral in CM chondrites, and is thought to have formed by precipitation from an aqueous fluid on the CM parent body within several million years of accretion. The petrographic context of crosscutting dolomite veins indicates that aqueous alteration occurred in situ, rather than in the nebular setting. Here, we present 53Mn-53Cr systematics for dolomite grains in Sutter's Mill section SM51-1. The Mn-Cr isotope data show well-resolved excesses of 53Cr correlated with 55Mn/52Cr ratio, which we interpret as evidence for the in situ decay of radioactive 53Mn. After correcting for the relative sensitivities of Mn and Cr using a synthetic Mn- and Cr-bearing calcite standard, the data yield an isochron with slope corresponding to an initial 53Mn/55Mn ratio of 3.42 ± 0.86 × 10-6. The reported error includes systematic uncertainty from the relative sensitivity factor. When calculated relative to the U-corrected Pb-Pb absolute age of the D'Orbigny angrite, Sutter's Mill dolomites give a formation age between 4564.8 and 4562.2 Ma (2.4-5.0 Myr after the birth of the solar system). This age is contemporaneous with previously reported ages for secondary carbonates in CM and CI chondrites. Consistent carbonate precipitation ages between the carbonaceous chondrite groups suggest that aqueous alteration was a common process during the early stages of parent body formation, probably occurring via heating from internal 26Al decay. The high-precision isochron for Sutter's Mill dolomite indicates that late-stage processing did not reach temperatures that were high enough to further disturb the Mn-Cr isochron.

  1. Primitive Liquid Water of the Solar System in an Aqueous Altered Carbonaceous Chondrite

    NASA Technical Reports Server (NTRS)

    Tsuchiyama, A.; Miyake, A.; Kitayama, A.; Matsuno, J.; Takeuchi, A.; Uesugi, K.; Suzuki, Y.; Nakano, T.; Zolensky, M. E.

    2016-01-01

    Non-destructive 3D observations of the aqueous altered CM chondrite Sutter's Mill using scanning imaging x-ray microscopy (SIXM) showed that some of calcite and enstatite grains contain two-phase inclusion, which is most probably composed of liquid water and bubbles. This water should be primitive water responsible for aqueous alteration in an asteroid in the early solar system.

  2. Origin of graphitic carbon and pentlandite in matrix olivines in the Allende meteorite.

    PubMed

    Brearley, A J

    1999-08-27

    Matrix olivines in the Allende carbonaceous chondrite are believed to have formed by condensation processes in the primitive solar nebula. However, transmission electron microscope observations of numerous matrix olivines show that they contain abundant, previously unrecognized, nanometer-sized inclusions of pentlandite and poorly graphitized carbon. Neither of these phases would have been stable at the high-temperature conditions required to condense iron-rich olivine in the solar nebula. The presence of these inclusions is consistent with formation of the olivines by parent body processes that involved overgrowth of fine-grained organic materials and sulfides in the precursor matrix materials.

  3. Oxygen- and magnesium-isotope compositions of calcium-aluminum-rich inclusions from CR2 carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Makide, Kentaro; Nagashima, Kazuhide; Krot, Alexander N.; Huss, Gary R.; Hutcheon, Ian D.; Bischoff, Addi

    2009-09-01

    We report both oxygen- and magnesium-isotope compositions measured in situ using a Cameca ims-1280 ion microprobe in 20 of 166 CAIs identified in 47 polished sections of 15 CR2 (Renazzo-type) carbonaceous chondrites. Two additional CAIs were measured for oxygen isotopes only. Most CR2 CAIs are mineralogically pristine; only few contain secondary phyllosilicates, sodalite, and carbonates - most likely products of aqueous alteration on the CR2 chondrite parent asteroid. Spinel, hibonite, grossite, anorthite, and melilite in 18 CAIs have 16O-rich (Δ 17O = -23.3 ± 1.9‰, 2 σ error) compositions and show no evidence for postcrystallization isotopic exchange commonly observed in CAIs from metamorphosed CV carbonaceous chondrites. The inferred initial 26Al/ 27Al ratios, ( 26Al/ 27Al) 0, in 15 of 16 16O-rich CAIs measured are consistent with the canonical value of (4.5-5) × 10 -5 and a short duration (<0.5 My) of CAI formation. These data do not support the "supra-canonical" values of ( 26Al/ 27Al) 0 [(5.85-7) × 10 -5] inferred from whole-rock and mineral isochrons of the CV CAIs. A hibonite-grossite-rich CAI El Djouf 001 MK #5 has uniformly 16O-rich (Δ 17O = -23.0 ± 1.7‰) composition, but shows a deficit of 26Mg and no evidence for 26Al. Because this inclusion is 16O-rich, like CAIs with the canonical ( 26Al/ 27Al) 0, we infer that it probably formed early, like typical CAIs, but from precursors with slightly nonsolar magnesium and lower-than-canonical 26Al abundance. Another 16O-enriched (Δ 17O = -20.3 ± 1.2‰) inclusion, a spinel-melilite CAI fragment Gao-Guenie (b) #3, has highly-fractionated oxygen- and magnesium-isotope compositions (˜11 and 23‰/amu, respectively), a deficit of 26Mg, and a relatively low ( 26Al/ 27Al) 0 = (2.0 ± 1.7) × 10 -5. This could be the first FUN ( Fractionation and Unidentified Nuclear effects) CAI found in CR2 chondrites. Because this inclusion is slightly 16O-depleted compared to most CR2 CAIs and has lower than the

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

    NASA Technical Reports Server (NTRS)

    Abreu, Neyda M.; Brearley, Adrian J.

    2005-01-01

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

  5. Mineralogy and Textural Characteristics of Fine-grained Rims in the Yamato 791198 CM2 Carbonaceous Chondrite: Constraints on the Location of Aqueous Alteration

    NASA Technical Reports Server (NTRS)

    Chizmadia, Lysa J.; Brearley, Adrian J.

    2003-01-01

    Carbonaceous chondrites provide important clues into the nature of physical and chemical processes in the early solar system. A question of key importance concerns the role of water in solar nebular and asteroidal processes. The effects of water on primary mineral assemblages have been widely recognized in chondritic meteorites, especially the CI and CM carbonaceous chondrites. These meteorites have undergone extensive aqueous alteration that occurred prior to their arrival on Earth. In the case of the CM chondrites, this alteration has resulted in the partial to complete replacement of the primary nebular phases with secondary alteration phases. Considerable controversy exists as to the exact location where the alteration of the CM chondrites occurred. Several textural lines of evidence have been cited in support of aqueous alteration prior to the accretion of the final parent asteroid. An important line of evidence to support this hypothesis is the dis-equilibrium nature of fine-grained rims and matrix materials. [2] also noted the juxtaposition of micron-sized Fe-Ni metal grains and apparently unaltered chondrule glass against hydrated rim silicates. Conversely, there is a large body of evidence in favor of parent body alteration such as the occurrence of undisturbed Fe-rich aureoles and the systematic redistribution of elemental components over millimeters, e.g., Mg(+2) into the matrix and Fe(+2) into chondrules etc.

  6. Discovery of a New Garnet Mineral, Hutcheonite, in the Allende Meteorite

    NASA Astrophysics Data System (ADS)

    Martel, L. M. V.

    2013-09-01

    A new titanium-rich garnet mineral has been found in a FUN CAI (a rare type of calcium-aluminum-rich inclusion, CAI) from the Allende carbonaceous chondrite, as reported by the discovery team of Chi Ma (CalTech) and Alexander Krot (University of Hawaii). The mineral, IMA 2013-029, was officially approved in June 2013 by the Commission on New Minerals, Nomenclature, and Classification of the International Mineralogical Association as hutcheonite. The mineral's name honors Ian D. Hutcheon, a researcher at Lawrence Livermore National Laboratory, who is a leading authority in the chronology of the early Solar System, especially known for his significant contributions to the development of instrumentation and techniques for isotopic and elemental microanalysis. Researchers Ma and Krot say hutcheonite in Allende is likely an alteration phase formed by iron-alkali-halogen metasomatism of the primary phases in the FUN CAI.

  7. Noble gases in 'phase Q' - Closed-system etching of an Allende residue

    NASA Technical Reports Server (NTRS)

    Wieler, Rainer; Baur, Heinrich; Signer, Peter; Anders, Edward; Lewis, Roy S.

    1991-01-01

    Results are presented from an analysis, in nearly pure form, of noble gases from the 'phase-Q' in an HF/HCl residue of the Allende C3V meteorite, using the closed-system stepped etching technique developed by Wieler et al. (1986) and Benkert et al. (1988) to extract noble gases from the residue. The results yield precise values of element and isotope abundances of all five noble gases in phase-Q, which is the major carrier of the planetary gases in carbonaceous chondrites. It was found that Ne-Q and Xe-Q in Allende are very similar to trapped gases in ureilites and in oxidizable carriers in several classes of ordinary chandrites, indicating that Q-gases are present in the formation locations of all these meteorites.

  8. Lithologies Making Up CM Carbonaceous Chondrites and Their Link to Space Exposure Ages

    NASA Technical Reports Server (NTRS)

    Gregory, Timothy; Zolensky, Michael E.; Trieman, Alan; Berger, Eve; Le, Loan; Fagan, Amy; Takenouchi, Atsushi; Velbel, Michael A.; Nishiizumi, Kuni

    2015-01-01

    Chondrite parent bodies are among the first large bodies to have formed in the early Solar System, and have since remained almost chemically unchanged having not grown large enough or quickly enough to undergo differentiation. Their major nonvolatile elements bear a close resemblance to the solar photosphere. Previous work has concluded that CM chondrites fall into at least four distinct space exposure age groups (0.1 megaannus, 0.2 megaannus, 0.6 megaannus and 2.0 megaannus), but the meaning of these groupings is unclear. It is possible that these meteorites came from different parent bodies which broke up at different times, or instead came from the same parent body which underwent multiple break-up events, or a combination of these scenarios.

  9. Lithologies Making Up CM Carbonaceous Chondrites and Their Link to Space Exposure Ages

    NASA Technical Reports Server (NTRS)

    Gregory, Timothy; Zolensky, Michael E.; Trieman, Alan; Berger, Eve; Le, Loan; Fagan, Amy; Takenouchi, Atsushi; Velbel, Michael A.; Nishiizumi, Kunihiko

    2015-01-01

    Chondrite parent bodies are among the first large bodies to have formed in the early Solar System, and have since remained almost chemically unchanged having not grown large enough or quickly enough to undergo differentiation. Their major nonvolatile elements bear a close resemblance to the solar photosphere. Previous work has concluded that CM chondrites fall into at least four distinct space exposure age groups (0.1 Ma, 0.2 Ma, 0.6 Ma and >2.0 Ma), but the meaning of these groupings is unclear. It is possible that these meteorites came from different parent bodies which broke up at different times, or instead came from the same parent body which underwent multiple break-up events, or a combination of these scenarios.

  10. Effects of Microsecond Pulse Laser Irradiation on Vis-NIR Reflectance Spectrum of Carbonaceous Chondrite Simulant: Implications for Martian Moons and Primitive Asteroids

    NASA Technical Reports Server (NTRS)

    Hiroi, T.; Moroz, L. V.; Shingareva, T. V.; Basilevsky, A. T.; Pieters, M.

    2003-01-01

    Goal of this study is to make a progress in understanding the optical effects of space weathering on small bodies believed to be similar in composition to carbonaceous chondrites: C, G, B, F, T, D, and P asteroids and possibly Martian satellites Phobos and Deimos. The companion work focuses on petrological and mineralogical aspects of this process. One of the main factors of space weathering is meteorite and micrometeorite bombardment leading, in particular, to impact melting of components of the regolith. Studies of lunar regolith and laboratory experiments simulating impact melting show that the melting products differ from the unmelted material in mineralogy and distribution of chemical components among different phases that results in spectral changes. We simulate impact melting of CM chondrite by pulse laser irradiation of an artificial analog of such a meteorite. The analog is a mixture of 46 wt.% non-magnetic fraction of L5 ordinary chondrite Tsarev, 47 wt.% serpentine, 5 wt.% kerite, and 2 wt.% calcite. It simulates rather well bulk chemistry, including volatiles such as H2O and CO2, and only approximately the CM chondrite mineralogy. Thus, we do not expect the mixture to be spectrally similar to CM chondrites, but expect the laser melting products to be similar to those formed by impact melting of natural CM chondrites.

  11. Highly siderophile and chalcogen element constraints on the origin of components of the Allende and Murchison meteorites

    NASA Astrophysics Data System (ADS)

    Kadlag, Yogita; Becker, Harry

    2016-06-01

    187Re-187Os systematics, abundances of highly siderophile elements (HSE: Re, PGE, and Au), chalcogen elements (Te, Se, and S), and some major and minor elements were determined in physically separated components of the Allende (CV3) and Murchison (CM2) carbonaceous chondrites. Substantial differences exist in the absolute and relative abundances of elements in the components, but the similarity of calculated and literature bulk rock abundances of HSE and chalcogens indicate that chemical complementarity exists among the components, with CI chondrite-like ratios for many elements. Despite subsequent alteration and oxidation, the overall cosmochemical behavior of most moderately to highly siderophile elements during high-temperature processing has been preserved in components of Allende at the sampling scale of the present study. The 187Re-187Os systematics and element variations of Allende are less disturbed compared with Murchison, which reflects different degrees of oxidation and alteration of these meteorites. The HSE systematics (with the exception of Au) is controlled by two types of materials: Pd-depleted condensates and CI chondrite-like material. Enrichment and heterogeneous distribution of Au among the components is likely the result of hydrothermal alteration. Chalcogen elements are depleted compared with HSE in all components, presumably due to their higher volatility. Small systematic variations of S, Se, and Te in components bear the signature of fractional condensation/partial evaporation and metal-sulfide-silicate partitioning.

  12. Chromium isotopic systematics of the Sutter's Mill carbonaceous chondrite: Implications for isotopic heterogeneities of the early solar system

    NASA Astrophysics Data System (ADS)

    Yamakawa, Akane; Yin, Qing-Zhu

    2014-11-01

    Recent studies have shown that major meteorite groups possess their own characteristic 54Cr values, demonstrating the utility of Cr isotopes for identifying genetic relationships between the planetary materials in conjunction with other classical tools, such as oxygen isotopes. In this study, we performed Cr isotope analyses for whole rocks and chemically separated phases of the new CM2 chondrite, Sutter's Mill (SM 43 and 51). The two whole rocks of Sutter's Mill show essentially identical ɛ54Cr excesses (SM 43 = +0.95 ± 0.09ɛ, SM 51 = +0.88 ± 0.07ɛ), relative to the Earth. These values are the same within error with that of the CM2-type Murchison (+0.89 ± 0.08ɛ), suggesting that parent bodies of Sutter's Mill and Murchison were formed from the same precursor materials in the solar nebula. Large ɛ54Cr excess of up to 29.40ɛ is observed in the silicate phase of Sutter's Mill, while that of Murchison shows 15.74ɛ. Importantly, the leachate fractions of both Sutter's Mill and Murchison form a steep linear anticorrelation between ɛ54Cr and ɛ53Cr, cross-cutting the positive correlation previously observed in carbonaceous chondrites. The fact that L4 acid leachate fraction contains higher 54Cr excesses than that of L5 step designed to dissolve refractory minerals suggests that spinel is not a major 54Cr carrier. We also note that L5 contains 53Cr anomalies lower than the solar initial value, suggesting it carries a component of nucleosynthetic anomaly unrelated to the 53Mn decay. We have identified five endmember components of nucleosynthetic origin among the early solar system materials.

  13. Formation and composition of the moon. [carbonaceous meteorites

    NASA Technical Reports Server (NTRS)

    Anderson, D. L.

    1974-01-01

    Many of the properties of the moon are discussed including the enrichment in Ca, Al, Ti, U, Th, Ba, Sr and the REE and the depletion in Fe, Rb, K, Na and other volatiles which could be understood if the moon represents a high temperature condensate from the solar nebula. Thermodynamic calculations show that Ca, Al and Ti rich compounds condense first in a cooling nebula. The initial high temperature mineralogy is gehlenite, spinel, perovskite, Ca-Al-rich pyroxenes and anorthite. Inclusions in Type III carbonaceous chondrites such as the Allende meteorite are composed primarily of these minerals and, in addition, are highly enriched in refractories such as REE relative to carbonaceous chondrites. These inclusions can yield basalt and anorthosite in the proportions required to eliminate the europium anomaly, leaving a residual spinel-melilite interior.

  14. Planetary Bioresources and Astroecology. 1. Planetary Microcosm Bioassays of Martian and Carbonaceous Chondrite Materials: Nutrients, Electrolyte Solutions, and Algal and Plant Responses

    NASA Astrophysics Data System (ADS)

    Mautner, Michael N.

    2002-07-01

    The biological fertilities of planetary materials can be assessed using microcosms based on meteorites. This study applies microcosm tests to martian meteorites and analogues and to carbonaceous chondrites. The biological fertilities of these materials are rated based on the soluble electrolyte nutrients, the growth of mesophile and cold-tolerant algae, and plant tissue cultures. The results show that the meteorites, in particular the Murchison CM2 carbonaceous chondrite and DaG 476 martian shergottite, contain high levels of water-extractable Ca, Mg, and SO 4-S. The martian meteorites DaG 476 and EETA 79001 also contain higher levels of extractable essential nutrients NO 3-N (0.013-0.017 g kg -1) and PO 4-P (0.019-0.046 g kg -1) than the terrestrial analogues. The yields of most of the water-extractable electrolytes vary only by factors of 2-3 under a wide range of planetary conditions. However, the long-term extractable phosphate increases significantly under a CO 2 atmosphere. The biological yields of algae and plant tissue cultures correlate with extractable NO 3-N and PO 4-P, identifying these as the limiting nutrients. Mesophilic algae and Asparagus officinalis cultures are identified as useful bioassay agents. A fertility rating system based on microcosm tests is proposed. The results rate the fertilities in the order martian basalts > terrestrial basalt, agricultural soil > carbonaceous chondrites, lava ash > cumulate igneous rock. The results demonstrate the application of planetary microcosms in experimental astroecology to rate planetary materials as targets for astrobiology exploration and as potential space bioresources. For example, the extractable materials in Murchison suggest that concentrated internal solutions in carbonaceous asteroids (3.8 mol L -1 electrolytes and 10 g L -1 organics) can support and disperse microorganisms introduced by natural or directed panspermia in early solar systems. The results also suggest that carbonaceous asteroids

  15. Experimental aqueous alteration of the Allende meteorite under oxidizing conditions: Constraints on asteroidal alteration

    NASA Astrophysics Data System (ADS)

    Jones, Catherine L.; Brearley, Adrian J.

    2006-02-01

    We have performed an experimental study of the aqueous alteration of the Allende CV3 carbonaceous chondrite under highly oxidizing conditions, in order to examine the alteration behavior of Allende's anhydrous mineralogy. The experiments were carried out at temperatures of 100, 150, and 200 °C, for time periods between 7 and 180 days, with water/rock ratios ranging from 1:1 to 9:1. Uncrushed cubes of Allende were used so that the spatial relationships between reactant and product phases could be examined in detail. Scanning electron microscope studies show that in all the experiments, even those of short duration (7 days), soluble salts of Ca and Mg (CaSO 4, CaCO 3, and MgSO 4) precipitated on the sample surface, indicating that these elements are rapidly mobilized during alteration. In addition, iron oxides and hydroxides formed on the sample surfaces. The sulfates, carbonates, and the majority of the iron-bearing secondary minerals are randomly distributed over the surface of samples. In some instances the iron oxides and hydroxides are constrained to the boundaries of altering mineral grains. Transmission electron microscope studies show that the FeO-rich olivine in the interior of the samples has altered to form interlayered serpentine/saponite and Fe-oxyhydroxides. The degree of alteration increases significantly with increasing water/rock ratio, and to a lesser extent with increasing duration of heating. The serpentine/saponite forms both by direct replacement of the olivine in crystallographically oriented intergrowths, and by recrystallization of an amorphous Si-rich phase that precipitates in pore space between the olivine grains. The alteration assemblage bears many similarities to those found in altered carbonaceous chondrites, although in detail there are important differences, which we attribute to (a) the relatively high temperatures of our experiments and (b) comparatively short reaction times compared with the natural examples. In terms of mineral

  16. The Insoluble Carbonaceous Material of CM Chondrites as Possible Source of Discrete Organics During the Asteroidal Aqueous Phase

    NASA Technical Reports Server (NTRS)

    Yabuta, H.; Williams, L.; Cody, G.; Pizzarello, S.

    2005-01-01

    The larger portion of the organic carbon in carbonaceous chondrites (CC) is present as a complex and heterogeneous macromolecular material that is insoluble in acids and most solvents (IOM). So far, it has been analyzed only as a whole by microscopy (TEM) and spectroscopy (IR, NMR, EPR), which have offered and overview of its chemical nature, bonding, and functional group composition. Chemical or pyrolytic decomposition has also been used in combination with GC-MS to identify individual compounds released by these processes. Their value in the recognition of the original IOM structure resides in the ability to properly interpret the decomposition pathways for any given process. We report here a preliminary study of IOM from the Murray meteorite that combines both the analytical approaches described above, under conditions that would realistically model the IOM hydrothermal exposure in the meteorite parent body. The aim is to document the possible release of water and solvent soluble organics, determine possible changes in NMR spectral features, and ascertain, by extension, the effect of this loss on the frame of the IOM residue. Additional information is included in the original extended abstract.

  17. Clasts in the CM2 carbonaceous chondrite Lonewolf Nunataks 94101: Evidence for aqueous alteration prior to complex mixing

    NASA Astrophysics Data System (ADS)

    Lindgren, Paula; Lee, Martin R.; Sofe, Mahmood R.; Zolensky, Michael E.

    2013-06-01

    Clasts in the CM2 carbonaceous chondrite Lonewolf Nunataks (LON) 94101 have been characterized using scanning and transmission electron microscopy and electron microprobe analysis to determine their degrees of aqueous alteration, and the timing of alteration relative to incorporation of clasts into the host. The provenance of the clasts, and the mechanism by which they were incorporated and mixed with their host material are also considered. Results show that at least five distinct types of clasts occur in LON 94101, of which four have been aqueously altered to various degrees and one is largely anhydrous. The fact that they have had different alteration histories implies that the main part of aqueous activity occurred prior to the mixing and assimilation of the clasts with their host. Further, the presence of such a variety of clasts suggests complex mixing in a dynamic environment involving material from various sources. Two of the clasts, one containing approximately 46 vol% carbonate and the other featuring crystals of pyrrhotite up to approximately 1 mm in size, are examples of unusual lithologies and indicate concentration of chemical elements in discrete areas of the parent body(ies), possibly by flow of aqueous solutions.

  18. NEW TITANIUM ISOTOPE DATA FOR ALLENDE AND EFREMOVKA CAIs

    SciTech Connect

    Leya, Ingo; Schoenbaechler, Maria; Kraehenbuehl, Urs; Halliday, Alex N.

    2009-09-10

    We measured the titanium (Ti) isotope composition, i.e., {sup 50}Ti/{sup 47}Ti, {sup 48}Ti/{sup 47}Ti, and {sup 46}Ti/{sup 47}Ti, in five calcium-rich-aluminum-rich refractory inclusions (CAIs) from the oxidized CV3 chondrite Allende and in two CAIs from the reduced CV3 chondrite Efremovka. Our data indicate that CAIs are enriched in {sup 50}Ti/{sup 47}Ti and {sup 46}Ti/{sup 47}Ti and are slightly depleted in {sup 48}Ti/{sup 47}Ti compared to normal Ti defined by ordinary chondrites, eucrites, ureilites, mesosiderites, Earth, Moon, and Mars. Some CAIs have an additional {sup 50}Ti excess of {approx}8{epsilon} relative to bulk carbonaceous chondrites, which are enriched in {sup 50}Ti by {approx}2{epsilon} relative to terrestrial values, leading to a total excess of {approx}10{epsilon}. This additional {sup 50}Ti excess is correlated with nucleosynthetic anomalies found in {sup 62}Ni and {sup 96}Zr, all indicating an origin from a neutron-rich stellar source. Bulk carbonaceous chondrites show a similar trend, however, the extent of the anomalies is either less than or similar to the smallest anomalies seen in CAIs. Mass balance calculations suggest that bulk Allende Ti possibly consists of a mixture of at least two Ti components, anomalous Ti located in CAIs and a normal component possibly for matrix and chondrules. This argues for a heterogeneous distribution of Ti isotopes in the solar system. The finding that anomalous Ti is concentrated in CAIs suggests that CAIs formed in a specific region of the solar system and were, after their formation, not homogeneously redistributed within the solar system. Combining the CAI data with improved model predictions for early solar system irradiation effects indicates that a local production scenario for the relatively short lived radionuclides can be excluded, because the production of, e.g., {sup 10}Be, {sup 26}Al, and {sup 41}Ca, would result in a significant collateral shift in Ti isotopes, which is not seen in the

  19. 16O excesses in olivine inclusions in Yamato-86009 and Murchison chondrites and their relation to CAIs.

    PubMed

    Hiyagon, H; Hashimoto, A

    1999-02-01

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

  20. 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.

  1. Incorporation of short-lived (10)Be in a calcium-aluminum-rich inclusion from the allende meteorite

    PubMed

    McKeegan; Chaussidon; Robert

    2000-08-25

    Enrichments in boron-10/boron-11 in a calcium-aluminum-rich inclusion from the Allende carbonaceous chondrite are correlated with beryllium/boron in a manner indicative of the in situ decay of short-lived beryllium-10. Because this radionuclide is produced only by nuclear spallation reactions, its existence in early solar system materials attests to intense irradiation processes in the solar nebula. The particle fluence inferred from the initial beryllium-10/beryllium-9 is sufficient to produce other short-lived nuclides, calcium-41 and manganese-53, found in meteorites, but the high canonical abundance of aluminum-26 may still require seeding of the solar system by radioactive stellar debris.

  2. Compound ultrarefractory CAI-bearing inclusions from CV3 carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Ivanova, Marina A.; Krot, Alexander N.; Nagashima, Kazuhide; MacPherson, Glenn J.

    2012-12-01

    Abstract-Two compound calcium-aluminum-rich inclusions (CAIs), 3N from the oxidized CV <span class="hlt">chondrite</span> Northwest Africa (NWA) 3118 and 33E from the reduced CV <span class="hlt">chondrite</span> Efremovka, contain ultrarefractory (UR) inclusions. 3N is a forsterite-bearing type B (FoB) CAI that encloses UR inclusion 3N-24 composed of Zr,Sc,Y-rich oxides, Y-rich perovskite, and Zr,Sc-rich Al,Ti-diopside. 33E contains a fluffy type A (FTA) CAI and UR CAI 33E-1, surrounded by Wark-Lovering rim layers of spinel, Al-diopside, and forsterite, and a common forsterite-rich accretionary rim. 33E-1 is composed of Zr,Sc,Y-rich oxides, Y-rich perovskite, Zr,Sc,Y-rich pyroxenes (Al,Ti-diopside, Sc-rich pyroxene), and gehlenite. 3N-24's UR oxides and Zr,Sc-rich Al,Ti-diopsides are 16O-poor (Δ17O approximately -2‰ to -5‰). Spinel in 3N-24 and spinel and Al-diopside in the FoB CAI are 16O-rich (Δ17O approximately -23 ± 2‰). 33E-1's UR oxides and Zr,Sc-rich Al,Ti-diopsides are 16O-depleted (Δ17O approximately -2‰ to -5‰) vs. Al,Ti-diopside of the FTA CAI and spinel (Δ17O approximately -23 ± 2‰), and Wark-Lovering rim Al,Ti-diopside (Δ17O approximately -7‰ to -19‰). We infer that the inclusions experienced multistage formation in nebular regions with different oxygen-isotope compositions. 3N-24 and 33E-1's precursors formed by evaporation/condensation above 1600 °C. 3N and 33E's precursors formed by condensation and melting (3N only) at significantly lower temperatures. 3N-24 and 3N's precursors aggregated into a compound object and experienced partial melting and thermal annealing. 33E-1 and 33E avoided melting prior to and after aggregation. They acquired Wark-Lovering and common forsterite-rich accretionary rims, probably by condensation, followed by thermal annealing. We suggest 3N-24 and 33E-1 originated in a 16O-rich gaseous reservoir and subsequently experienced isotope exchange in a 16O-poor gaseous reservoir. Mechanism and timing of oxygen-isotope exchange remain</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19770064912&hterms=Alkyl+dimethyl&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DAlkyl%2Bdimethyl','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19770064912&hterms=Alkyl+dimethyl&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DAlkyl%2Bdimethyl"><span id="translatedtitle">Origin of organic matter in the early solar system. VII - The organic polymer in <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hayatsu, R.; Matsuoka, S.; Anders, E.; Scott, R. G.; Studier, M. H.</p> <p>1977-01-01</p> <p>Degradation techniques, including pyrolysis, depolymerization, and oxidation, were used to study the insoluble polymer from the Murchison C2 <span class="hlt">chondrite</span>. Oxidation with Cr2O7(2-) or O2/UV led to the identification of 15 aromatic ring systems. Of 11 aliphatic acids identified, three dicarboxylic acids presumably came from hydroaromatic portions of the polymer, whereas eight monocarboxylic acids probably derive from bridging groups or ring substituents. Depolymerization with CF3COO4 yielded some of the same ring systems, as well as alkanes (C1 through C8) and alkenes (C2 through C8), alkyl (C1 through C5) benzenes and naphthalenes, and methyl- or dimethyl -indene, -indane, -phenol, -pyrrole, and -pyridine. All these compounds were detected below 200 C, and are therefore probably indigenous constituents. The properties of the meteoritic polymer were compared with the properties of a synthetic polymer produced by the Fischer-Tropsch reaction. It is suggested that the meteoritic polymer was also produced by surface catalysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4657624','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4657624"><span id="translatedtitle">Petrography, stable isotope compositions, microRaman spectroscopy, and presolar components of Roberts Massif 04133: A reduced CV3 <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Davidson, Jemma; Schrader, Devin L; Alexander, Conel M O'D; Lauretta, Dante S; Busemann, Henner; Franchi, Ian A; Greenwood, Richard C; Connolly, Harold C; Domanik, Kenneth J; Verchovsky, Alexander</p> <p>2014-01-01</p> <p>Here, we report the mineralogy, petrography, C-N-O-stable isotope compositions, degree of disorder of organic matter, and abundances of presolar components of the <span class="hlt">chondrite</span> Roberts Massif (RBT) 04133 using a coordinated, multitechnique approach. The results of this study are inconsistent with its initial classification as a Renazzo-like <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span>, and strongly support RBT 04133 being a brecciated, reduced petrologic type >3.3 Vigarano-like <span class="hlt">carbonaceous</span> (CV) <span class="hlt">chondrite</span>. RBT 04133 shows no evidence for aqueous alteration. However, it is mildly thermally altered (up to approximately 440 °C); which is apparent in its whole-rock C and N isotopic compositions, the degree of disorder of C in insoluble organic matter, low presolar grain abundances, minor element compositions of Fe,Ni metal, chromite compositions and morphologies, and the presence of unequilibrated silicates. Sulfides within type I chondrules from RBT 04133 appear to be pre-accretionary (i.e., did not form via aqueous alteration), providing further evidence that some sulfide minerals formed prior to accretion of the CV <span class="hlt">chondrite</span> parent body. The thin section studied contains two reduced CV3 lithologies, one of which appears to be more thermally metamorphosed, indicating that RBT 04133, like several other CV <span class="hlt">chondrites</span>, is a breccia and thus experienced impact processing. Linear foliation of chondrules was not observed implying that RBT 04133 did not experience high velocity impacts that could lead to extensive thermal metamorphism. Presolar silicates are still present in RBT 04133, although presolar SiC grain abundances are very low, indicating that the progressive destruction or modification of presolar SiC grains begins before presolar silicate grains are completely unidentifiable. PMID:26640360</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014M%26PS...49.2133D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014M%26PS...49.2133D"><span id="translatedtitle">Petrography, stable isotope compositions, microRaman spectroscopy, and presolar components of Roberts Massif 04133: A reduced CV3 <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Davidson, Jemma; Schrader, Devin L.; Alexander, Conel M. O'd.; Lauretta, Dante S.; Busemann, Henner; Franchi, Ian A.; Greenwood, Richard C.; Connolly, Harold C.; Domanik, Kenneth J.; Verchovsky, Alexander</p> <p>2014-12-01</p> <p>Here, we report the mineralogy, petrography, C-N-O-stable isotope compositions, degree of disorder of organic matter, and abundances of presolar components of the <span class="hlt">chondrite</span> Roberts Massif (RBT) 04133 using a coordinated, multitechnique approach. The results of this study are inconsistent with its initial classification as a Renazzo-like <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span>, and strongly support RBT 04133 being a brecciated, reduced petrologic type >3.3 Vigarano-like <span class="hlt">carbonaceous</span> (CV) <span class="hlt">chondrite</span>. RBT 04133 shows no evidence for aqueous alteration. However, it is mildly thermally altered (up to approximately 440 °C); which is apparent in its whole-rock C and N isotopic compositions, the degree of disorder of C in insoluble organic matter, low presolar grain abundances, minor element compositions of Fe,Ni metal, chromite compositions and morphologies, and the presence of unequilibrated silicates. Sulfides within type I chondrules from RBT 04133 appear to be pre-accretionary (i.e., did not form via aqueous alteration), providing further evidence that some sulfide minerals formed prior to accretion of the CV <span class="hlt">chondrite</span> parent body. The thin section studied contains two reduced CV3 lithologies, one of which appears to be more thermally metamorphosed, indicating that RBT 04133, like several other CV <span class="hlt">chondrites</span>, is a breccia and thus experienced impact processing. Linear foliation of chondrules was not observed implying that RBT 04133 did not experience high velocity impacts that could lead to extensive thermal metamorphism. Presolar silicates are still present in RBT 04133, although presolar SiC grain abundances are very low, indicating that the progressive destruction or modification of presolar SiC grains begins before presolar silicate grains are completely unidentifiable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110011647','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110011647"><span id="translatedtitle">In-Situ Oxygen Isotopic Composition of Tagish Lake: An Ungrouped Type 2 <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zolensky, Michael E.; Engrand, Cecile; Gounelle, Matthieu; Zolensky, Mike E.</p> <p>2001-01-01</p> <p> isotopic fractionation would argue for a low temperature (CM-like, T approximately 0 deg) formation. Magnetite probably formed during a separate event. Tagish Lake magnetite data is surprisingly compatible with that of R-<span class="hlt">chondrites</span> and unequilibrated ordinary (LL3) <span class="hlt">chondrites</span>. Our oxygen isotope data strongly supports the hypothesis of a single precursor for both lithologies. Drastic mineralogical changes between the two lithologies not being accompanied with isotopic fractionation seem compatible with the alteration model presented by Young et aI. Tagish Lake probably represents the first well preserved large sample of the C2 matter that dominates interplanetary matter since the formation of the solar system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040062420&hterms=iron+phosphates&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Diron%2Bphosphates','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040062420&hterms=iron+phosphates&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Diron%2Bphosphates"><span id="translatedtitle">A Quantitative NMR Analysis of Phosphorus in <span class="hlt">Carbonaceous</span> and Ordinary <span class="hlt">Chondrites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pasek, M. A.; Smith, V. D.; Lauretta, D. S.</p> <p>2004-01-01</p> <p>Phosphorus is important in a number of biochemical molecules, from DNA to ATP. Early life may have depended on meteorites as a primary source of phosphorus as simple dissolution of crustal apatite may not produce the necessary concentration of phosphate. Phosphorus is found in several mineral phases in meteorites. Apatite and other Ca- and Mg phosphate minerals tend to be the dominant phosphorus reservoir in stony meteorites, whereas in more iron-rich or reduced meteorites, the phosphide minerals schreibersite, (Fe, Ni)3P, and perryite, (Ni, Fe)5(Si, P)2 are dominant. However, in CM <span class="hlt">chondrites</span> that have experienced significant aqueous alteration, phosphorus has been detected in more exotic molecules. A series of phosphonic acids including methyl-, ethyl-, propyl- and butyl- phosphonic acids were observed by GC-MS in Murchison. Phosphorian sulfides are in Murchison and Murray. NMR spectrometry is capable of detecting multiple substances with one experiment, is non-destructive, and potentially quantitative, as discussed below. Despite these advantages, NMR spectrometry is infrequently applied to meteoritic studies due in large part to a lack of applicability to many compounds and the relatively high limit of detection requirements. Carbon-13 solid-state NMR has been applied to macromolecular carbon in Murchison. P-31 NMR has many advantages over aqueous carbon-13 NMR spectrometry. P-31 is the only isotope of phosphorus, and P-31 gives a signal approximately twice as strong as C-13. These two factors together with the relative abundances of carbon and phosphorus imply that phosphorus should give a signal approximately 20 as strong as carbon in a given sample. A discussion on the preparation of the quantitative standard and NMR studies are presented</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=547833','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=547833"><span id="translatedtitle">Short-lived chlorine-36 in a Ca- and Al-rich inclusion from the Ningqiang <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lin, Yangting; Guan, Yunbin; Leshin, Laurie A.; Ouyang, Ziyuan; Wang, Daode</p> <p>2005-01-01</p> <p>Excesses of sulfur-36 in sodalite, a chlorine-rich mineral, in a calcium- and aluminum-rich inclusion from the Ningqiang <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> linearly correlate with chorine/sulfur ratios, providing direct evidence for the presence of short-lived chlorine-36 (with a half-life of 0.3 million years) in the early solar system. The best inferred (36Cl/35Cl)o ratios of the sodalite are ≈5 × 10-6. Different from other short-lived radionuclides, chlorine-36 was introduced into the inclusion by solid-gas reaction during secondary alteration. The alteration reaction probably took place at least 1.5 million years after the first formation of the inclusion, based on the correlated study of the 26Al-26Mg systems of the relict primary minerals and the alteration assemblages, from which we inferred an initial ratio of (36Cl/35Cl)o > 1.6 × 10-4 at the time when calcium- and aluminum-rich inclusions formed. This discovery supports a supernova origin of short-lived nuclides [Cameron, A. G. W., Hoeflich, P., Myers, P. C. & Clayton, D. D. (1995) Astrophys. J. 447, L53; Wasserburg, G. J., Gallino, R. & Busso, M. (1998) Astrophys. J. 500, L189–L193], but presents a serious challenge for local irradiation models [Shu, F. H., Shang, H., Glassgold, A. E. & Lee, T. (1997) Science 277, 1475–1479; Gounelle, M., Shu, F. H., Shang, H., Glassgold, A. E., Rehm, K. E. & Lee, T. (2001) Astrophys. J. 548, 1051–1070]. Furthermore, the short-lived 36Cl may serve as a unique fine-scale chronometer for volatile-rock interaction in the early solar system because of its close association with aqueous and/or anhydrous alteration processes. PMID:15671168</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016M%26PS...51.1003L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016M%26PS...51.1003L"><span id="translatedtitle">Aqueous alteration of chondrules from the Murchison CM <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span>: Replacement, pore filling, and the genesis of polyhedral serpentine</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, M. R.; Lindgren, P.</p> <p>2016-06-01</p> <p>Forsterite and clinoenstatite in type IAB chondrules from the Murchison CM <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> have been partially serpentinized, and the mechanisms of their alteration reveal crystallographic and microstructural controls on the reaction of silicate minerals with parent body aqueous solutions. Grains of forsterite were altered in two stages. Narrow veinlets of Fe-rich serpentine formed first and by the filling of sheet pores. Most of these pores were oriented parallel to (010) and (001) and had been produced by earlier fracturing and/or congruent dissolution. In the second stage, the subset of veinlets that were oriented parallel to (001) was widened accompanying the replacement of forsterite by Mg-Fe serpentine. This reaction proceeded most rapidly parallel to [001], and crystallographic controls on the trajectory of retreating vein walls created fine-scale serrations. Murchison clinoenstatite grains have a skeletal appearance due to the presence of abundant veinlets and patches of phyllosilicate. Two alteration stages can again be recognized, with initial water-mineral interaction producing tochilinite-rich veinlets by the filling of (001)-parallel contraction cracks. Pores then formed by congruent dissolution that was guided principally by orthopyroxene lamellae, and they were subsequently filled by submicrometer-sized crystals of polyhedral serpentine. This finding that Murchison forsterite and clinoenstatite grains have been altered demonstrates that aqueous processing of magnesium silicate minerals started much earlier in CM parent body history than previously believed. Our results also show that the occurrence of polyhedral serpentine can be used to locate former pore spaces within the parent body.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15671168','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15671168"><span id="translatedtitle">Short-lived chlorine-36 in a Ca- and Al-rich inclusion from the Ningqiang <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lin, Yangting; Guan, Yunbin; Leshin, Laurie A; Ouyang, Ziyuan; Wang, Daode</p> <p>2005-02-01</p> <p>Excesses of sulfur-36 in sodalite, a chlorine-rich mineral, in a calcium- and aluminum-rich inclusion from the Ningqiang <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> linearly correlate with chorine/sulfur ratios, providing direct evidence for the presence of short-lived chlorine-36 (with a half-life of 0.3 million years) in the early solar system. The best inferred (36Cl/35Cl)o ratios of the sodalite are approximately 5 x 10(-6). Different from other short-lived radionuclides, chlorine-36 was introduced into the inclusion by solid-gas reaction during secondary alteration. The alteration reaction probably took place at least 1.5 million years after the first formation of the inclusion, based on the correlated study of the 26Al-26Mg systems of the relict primary minerals and the alteration assemblages, from which we inferred an initial ratio of (36Cl/35Cl)o > or = 1.6 x 10(-4) at the time when calcium- and aluminum-rich inclusions formed. This discovery supports a supernova origin of short-lived nuclides [Cameron, A. G. W., Hoeflich, P., Myers, P. C. & Clayton, D. D. (1995) Astrophys. J. 447, L53; Wasserburg, G. J., Gallino, R. & Busso, M. (1998) Astrophys. J. 500, L189-L193], but presents a serious challenge for local irradiation models [Shu, F. H., Shang, H., Glassgold, A. E. & Lee, T. (1997) Science 277, 1475-1479; Gounelle, M., Shu, F. H., Shang, H., Glassgold, A. E., Rehm, K. E. & Lee, T. (2001) Astrophys. J. 548, 1051-1070]. Furthermore, the short-lived 36Cl may serve as a unique fine-scale chronometer for volatile-rock interaction in the early solar system because of its close association with aqueous and/or anhydrous alteration processes. PMID:15671168</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015E%26PSL.426..101H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015E%26PSL.426..101H"><span id="translatedtitle">Hydrogen and carbon isotopic ratios of polycyclic aromatic compounds in two CM2 <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> and implications for prebiotic organic synthesis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Yongsong; Aponte, José C.; Zhao, Jiaju; Tarozo, Rafael; Hallmann, Christian</p> <p>2015-09-01</p> <p>Study of meteoritic organic compounds offers a unique opportunity to understand the origins of the organic matter in the early Solar System. Meteoritic polycyclic aromatic hydrocarbons (PAHs) and heteropolycyclic aromatic compounds (HACs) have been studied for over fifty years, however; their hydrogen stable isotopic ratios (δD) have never been reported. Compound-specific δD measurements of PAHs and HACs are important, in part because the carbon isotopic ratios (δ13C) of various meteoritic PAHs cannot be readily distinguished from their terrestrial counterparts and it is difficult to rule out terrestrial contamination based on carbon isotopic ratios alone. In this study, we have extracted and identified more than sixty PAHs and HACs present in two CM2 <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> Murchison and LON 94101. Their carbon and hydrogen stable isotopic ratios (δ13C and δD) were measured and used to discuss about their synthetic environments and formation mechanisms. The concentration of aromatic compounds is ∼30% higher in Murchison than in the Antarctic meteorite LON 94101, but both samples contained similar suites of PAHs and HACs. All PAHs and HACs found exhibited positive δD values (up to 1100‰) consistent with an extraterrestrial origin, indicating the relatively low δ13C values are indeed an inherent feature of the meteoritic aromatic compounds. The hydrogen isotopic data suggest aromatic compounds in <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> were mainly formed in the cold interstellar environments. Molecular level variations in hydrogen and carbon isotopic values offer new insights to the formation pathways for the aromatic compounds in <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950032166&hterms=alanine&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dalanine','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950032166&hterms=alanine&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dalanine"><span id="translatedtitle">The Strecker synthesis from interstellar precursors as a source of amino acids in <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>: Deuterium retention during synthesis. [Abstract only</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lerner, N. R.; Peterson, E.; Chang, S.</p> <p>1994-01-01</p> <p>Amino acids in the Murchison <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> are anomalously enriched in deuterium. Synthesis in Strecker reactions from D-enriched interstellar precursors during low temperature aqueous alteration of the parent body has been proposed by Cronin et al. (1988) to account for the isotopic observations. To test this hypothesis, we have measured the retention of deuterium in the glycine, alanine, and alpha-amino isobutyric acid produced, respectively, by reactions of formaldehyde-D2, acetaldehyde-D4, and acetone-D6 with HCN and NH3 in water.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011M%26PS...46..989R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011M%26PS...46..989R"><span id="translatedtitle">Cosmogenic helium and neon in individual chondrules from <span class="hlt">Allende</span> and Murchison: Implications for the precompaction exposure history of chondrules</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roth, A. S. G.; Baur, H.; Heber, V. S.; Reusser, E.; Wieler, R.</p> <p>2011-07-01</p> <p>We analyzed cosmogenic He and Ne in more than 60 individual chondrules separated from small chips from the <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> <span class="hlt">Allende</span> and Murchison. The goal of this work is to search for evidence of an exposure of chondrules to energetic particles—either solar or galactic—prior to final compaction of their host <span class="hlt">chondrites</span> and prior to the exposure of the meteoroids to galactic cosmic rays (GCR) on their way to Earth. Production rates of GCR-produced He and Ne are calculated for each chondrule based on major element composition and a physical model of cosmogenic nuclide production in <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> (Leya and Masarik 2009). All studied chondrules in <span class="hlt">Allende</span> show nominal exposure ages identical to each other within uncertainties of a few hundred thousand years. <span class="hlt">Allende</span> chondrules therefore show no signs of a precompaction exposure. The majority of the Murchison chondrules (the "normal" chondrules) also have nominal exposure ages identical within a few hundred thousand years. However, roughly 20% of the studied Murchison chondrules (the "pre-exposed" chondrules) contain considerably or even much higher concentrations of cosmogenic noble gases than the normal chondrules, equivalent to exposure ages to GCR at present-day fluxes in a 4π irradiation of up to about 30 Myr. The data do not allow to firmly conclude whether these excesses were acquired by an exposure of the pre-exposed chondrules to an early intense flux of solar energetic particles (solar cosmic rays) or rather by an exposure to GCR in the regolith of the Murchison parent asteroid. However, we prefer the latter explanation. Two major reasons are the GCR-like isotopic composition of the excess Ne and the distribution of solar flare tracks in Murchison samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeCoA.131..402A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeCoA.131..402A"><span id="translatedtitle">Highly siderophile elements and 187Re-187Os isotopic systematics of the <span class="hlt">Allende</span> meteorite: Evidence for primary nebular processes and late-stage alteration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Archer, G. J.; Ash, R. D.; Bullock, E. S.; Walker, R. J.</p> <p>2014-04-01</p> <p>The abundances of highly siderophile elements (HSE) Re, Os, Ir, Ru, Pt, and Pd, as well as 187Re-187Os isotopic systematics were determined for calcium-aluminum-rich inclusions (CAIs), chondrules, and matrix, separated from the CV3 <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> <span class="hlt">Allende</span>. Consistent with prior studies, CAIs are characterized by significant depletions in Pd relative to the other HSE, while the other HSE are in generally bulk <span class="hlt">chondritic</span> relative abundances. The depletions in Pd can be linked with initial formation of CAIs via condensation, or subsequent processing by evaporative processes. Chondrules generally have relative HSE patterns similar to CAIs, although they have lower absolute abundances. Palladium depletions in chondrules may reflect solid metal-liquid metal fractionation at the time of formation, or alternatively, be the result of processes that acted on precursor materials. Matrix samples have nearly <span class="hlt">chondritic</span> absolute abundances of all HSE measured. Consequently, matrix is the only major <span class="hlt">chondritic</span> component examined here that shows no relative depletion in Pd. Mass balance suggests the existence of an unidentified Pd-rich carrier, although it is possible that the dataset presented here is too limited to represent typical HSE abundances of some <span class="hlt">chondritic</span> components (e.g., chondrules). The 187Re-187Os isotopic systematics of only six out of twenty-four <span class="hlt">Allende</span> <span class="hlt">chondritic</span> components analyzed plot within uncertainties of a 4568 Ma primordial reference isochron. The deviations from the expected isochron most likely reflect late-stage, open-system behavior within the last 2 billion years, and, in some cases, could even have resulted from terrestrial alteration. The open-system behavior is most readily observed in small, millimeter-size sub-samples of <span class="hlt">Allende</span>, consistent with Re and/or Os mobility on that scale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015LPICo1856.5205M&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015LPICo1856.5205M&link_type=ABSTRACT"><span id="translatedtitle">Zn Isotopes in <span class="hlt">Chondrites</span>, Chondrules, and Matrix: Origin of the Volatile Element Depletion in <span class="hlt">Chondrites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moynier, F.; Pringle, E.; Hezel, D.</p> <p>2015-07-01</p> <p>The variations of Zn isotope ratios among <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> show that the volatile element depletion in solar system material occurred in the solar nebula. We will also present the Zn isotopic composition of chondrules and matrix from <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1992Metic..27R.305W&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1992Metic..27R.305W&link_type=ABSTRACT"><span id="translatedtitle">Thermal History of the <span class="hlt">Allende</span> Parent Body</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weinbruch, S.; Armstrong, J. T.; Palme, H.</p> <p>1992-07-01</p> <p>Little is known about the temperature of accretion of <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> parent bodies and their subsequent thermal history. The frequent indicators of thermodynamic disequilibrium present in <span class="hlt">Allende</span> (e.g., chemical zoning of olivine and pyroxene) clearly demonstrate that parent body metamorphism was limited to low temperatures and/or short periods of time. In order to quantify maximum temperatures and timescales we have studied chemical zoning of olivine and Fe/Mg exchange between coexisting olivine and chromite (olivine/spinel thermometry). We have analyzed 43 olivine-chromite pairs in type II chondrules and Fe-rich single olivine grains from <span class="hlt">Allende</span> with the electron microprobe and calculated equilibration temperatures between 1500 K and 800 K (uncertainties are in the order of 200 K depending on various calibrations of the exchange reaction). In a few grains high temperatures, between 1300 and 1500 K (depending on the calibration), are preserved, which may be interpreted as chondrule crystallization temperatures. Most grains, however, yield much lower temperatures between 800 and 1000 K, presumably representing closure temperatures for Fe/Mg interdiffusion. The lowest temperatures of about 800 K may be regarded as an upper limit for metamorphic peak temperatures. In the few cases where higher temperatures are preserved, chromite grains are extraordinarily large, preventing low-temperature equilibration. Chemical zoning of <span class="hlt">Allende</span> olivine indicates that temperatures in the parent body are below 800 K. In some olivine grains steep Fe/Mg concentration profiles across the boundary between forsteritic cores and fayalite-rich rims were observed, with FeO contents increasing by about 30 wt% within 5 micrometers (Weinbruch et al., 1990). The maximum time such steep concentration profiles could be retained at a given temperature was calculated using Fe/Mg interdiffusion coefficients of Buening and Buseck (1973) and Misener (1974). In extrapolating the Misener (1974</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10558982','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10558982"><span id="translatedtitle">Fluid flow in <span class="hlt">chondritic</span> parent bodies: deciphering the compositions of planetesimals</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Young; Ash; England; Rumble</p> <p>1999-11-12</p> <p>Alteration of the <span class="hlt">Allende</span> 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 <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> and displacement of the terrestrial planets from the primordial slope 1. 00 line on the oxygen three-isotope plot.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040062227&hterms=nickel&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dnickel','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040062227&hterms=nickel&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dnickel"><span id="translatedtitle">A Unique Style of Alteration of Iron-Nickel Metal in WIS91600, an Unusual C2 <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brearley, Adrian J.</p> <p>2004-01-01</p> <p>The collection of meteorites from Antarctica has provided an invaluable resource of new materials for study by the scientific community. In addition to exciting finds of new meteorite types (e.g. ALH85085, LEW 85332), these efforts have generated many important samples of existing meteorite groups, particularly C2 <span class="hlt">chondrites</span>. Studies of these <span class="hlt">chondrites</span> have broadened our understanding of aqueous alteration and provided a much more comprehensive view of the diversity of alteration in these meteorites. In this study, I report the findings of a petrographic and TEM study of WIS91600, a C2 <span class="hlt">chondrite</span> that has experienced a highly unusual style of aqueous alteration that has not previously been recognized in C2 <span class="hlt">chondrites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016LPICo1921.6055G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016LPICo1921.6055G"><span id="translatedtitle">Origin of Water in Earth with High D/H Ratio Relative to Protosolar Nebula, and an Explanation of its Similarity with the Isotopic Ratios of <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrites</span> and Asteroid Vesta</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ganguly, J.; Asaduzzaman, A.; Muralidharan, K.</p> <p>2016-08-01</p> <p>The elevated D/H ratio of the Earth and its similarity with that of <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> and Asteroid Vesta could be a consequence of gas-grain isotopic fractionation in the solar nebula that was somewhat pre-enriched in D from extraneous sources.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160002373','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160002373"><span id="translatedtitle">Organic Analysis in Miller Range 090657 and Buckley Island 10933 CR2 <span class="hlt">Chondrites</span>: Part 1 In-Situ Observation of <span class="hlt">Carbonaceous</span> Material</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cao, T.; Nakamura-Messenger, K.; Berger, E. L.; Burton, A. S.; Messenger, S.; Clemett, S. J.</p> <p>2016-01-01</p> <p>Primitive <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> contain a wide variety of organic material, ranging from soluble discrete molecules to insoluble unstructured kerogen-like component as well as structured nano-globules of macromolecular carbon. The relationship between the soluble organic molecules, macromolecular organic material, and host minerals are poorly understood. Due to the differences in extractability of soluble and insoluble organic materials, the analysis methods for each differ and are often performed independently. The combination of soluble and insoluble analyses, when performed concurrently, can provide a wider understanding on spatial distribution, and elemental, structural and isotopic composition of organic material in primitive meteorites. Furthermore, they can provide broader perspective on how extraterrestrial organic ma-terials potentially contributed to the synthesis of life's essential compounds such as amino acids, sugar acids, activated phosphates and nucleobases.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/973864','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/973864"><span id="translatedtitle">Distribution and Origin of 36Cl In <span class="hlt">Allende</span> CAIs</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Matzel, J P; Jacobsen, B; Hutcheon, I D; Krot, A N; Nagashima, K; Yin, Q; Ramon, E C; Weber, P; Wasserburg, G J</p> <p>2009-12-11</p> <p>The abundance of short-lived radionuclides (SLRs) in early solar system materials provide key information about their nucleosynthetic origin and can constrain the timing of early solar system events. Excesses of {sup 36}S ({sup 36}S*) correlated with {sup 35}Cl/{sup 34}S ratios provide direct evidence for in situ decay of {sup 36}Cl ({tau}{sub 1/2} {approx} 0.3 Ma) and have been reported in sodalite (Na{sub 8}Al{sub 6}Si{sub 6}O{sub 24}Cl{sub 2}) and wadalite (Ca{sub 6}Al{sub 5}Si{sub 2}O{sub 16}Cl{sub 3}) in CAIs and chondrules from the <span class="hlt">Allende</span> and Ningqiang CV <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>. While previous studies demonstrate unequivocally that {sup 36}Cl was extant in the early solar system, no consensus on the origin or initial abundance of {sup 36}Cl has emerged. Understanding the origin of {sup 36}Cl, as well as the reported variation in the initial {sup 36}Cl/{sup 35}Cl ratio, requires addressing when, where and how chlorine was incorporated into CAIs and chondrules. These factors are key to distinguishing between stellar nucleosynthesis or energetic particle irradiation for the origin of {sup 36}Cl. Wadalite is a chlorine-rich secondary mineral with structural and chemical affinities to grossular. The high chlorine ({approx}12 wt%) and very low sulfur content (<<0.01 wt%) make wadalite ideal for studies of the {sup 36}Cl-{sup 36}S system. Wadalite is present in <span class="hlt">Allende</span> CAIs exclusively in the interior regions either in veins crosscutting melilite or in zones between melilite and anorthite associated with intergrowths of grossular, monticellite, and wollastonite. Wadalite and sodalite most likely resulted from open-system alteration of primary minerals with a chlorine-rich fluid phase. We recently reported large {sup 36}S* correlated with {sup 35}Cl/{sup 34}S in wadalite in <span class="hlt">Allende</span> Type B CAI AJEF, yielding a ({sup 36}Cl/{sup 35}Cl){sub 0} ratio of (1.7 {+-} 0.3) x 10{sup -5}. This value is the highest reported {sup 36}Cl/{sup 35}Cl ratio and is {approx}5 times</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910046582&hterms=American+Museum+of+Natural+History&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3D%2528%2528%2528%2528American%2BMuseum%2529%2Bof%2529%2BNatural%2529%2BHistory%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910046582&hterms=American+Museum+of+Natural+History&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3D%2528%2528%2528%2528American%2BMuseum%2529%2Bof%2529%2BNatural%2529%2BHistory%2529"><span id="translatedtitle">Chromite and olivine in type II chondrules in <span class="hlt">carbonaceous</span> and ordinary <span class="hlt">chondrites</span> - Implications for thermal histories and group differences</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Johnson, Craig A.; Prinz, Martin</p> <p>1991-01-01</p> <p>Unequilibrated chromite and olivine margin compositions in type II chondrules are noted to differ systematically among three of the <span class="hlt">chondrite</span> groups, suggesting that type II liquids differed in composition among the groups. These differences may be interpreted as indicators of different chemical compositions of the precursor solids which underwent melting, or, perhaps, as differences in the extent to which immiscible metal sulfide droplets were lost during chondrule formation. Because zinc is detectable only in type II chromites which have undergone reequilibration, the high zinc contents reported for <span class="hlt">chondritic</span> chromites in other studies probably reflect redistribution during thermal metamorphism.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMGP51B3736K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMGP51B3736K"><span id="translatedtitle">More evidence for a partially differentiated CV <span class="hlt">chondrite</span> parent body from paleomagnetic studies of ALH 84028 and ALH 85006</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Klein, B. Z.; Weiss, B. P.; Carporzen, L.</p> <p>2014-12-01</p> <p>Recent paleomagnetic studies of the CV <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> <span class="hlt">Allende</span> and Kaba and numerical modeling studies have suggested that the CV <span class="hlt">chondrite</span> parent body may have been partially differentiated, with a molten metallic core, dynamo magnetic field, and an unmelted <span class="hlt">chondritic</span> lid. To further evaluate this hypothesis, here we present new paleomagnetic analyses of two previously unstudied CV3 <span class="hlt">chondrites</span>: the unshocked, <span class="hlt">Allende</span>-type oxidized <span class="hlt">chondrite</span> ALH 84028 and the weakly shocked, Bali-type oxidized <span class="hlt">chondrite</span> 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 <span class="hlt">chondrite</span> 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 <span class="hlt">Allende</span> and Kaba, there is now consistent evidence for dynamo fields from four CV <span class="hlt">chondrites</span> 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 <span class="hlt">Allende</span> (9-10 Ma and 2-3 Ma after Stillwater respectively), CV parent body</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26PSL.454..293B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26PSL.454..293B"><span id="translatedtitle">Molybdenum isotopic evidence for the origin of chondrules and a distinct genetic heritage of <span class="hlt">carbonaceous</span> and non-<span class="hlt">carbonaceous</span> meteorites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Budde, Gerrit; Burkhardt, Christoph; Brennecka, Gregory A.; Fischer-Gödde, Mario; Kruijer, Thomas S.; Kleine, Thorsten</p> <p>2016-11-01</p> <p>Nucleosynthetic isotope anomalies are powerful tracers to determine the provenance of meteorites and their components, and to identify genetic links between these materials. Here we show that chondrules and matrix separated from the <span class="hlt">Allende</span> CV3 <span class="hlt">chondrite</span> have complementary nucleosynthetic Mo isotope anomalies. These anomalies result from the enrichment of a presolar carrier enriched in s-process Mo into the matrix, and the corresponding depletion of this carrier in the chondrules. This carrier most likely is a metal and so the uneven distribution of presolar material probably results from metal-silicate fractionation during chondrule formation. The Mo isotope anomalies correlate with those reported for W isotopes on the same samples in an earlier study, suggesting that the isotope variations for both Mo and W are caused by the heterogeneous distribution of the same carrier. The isotopic complementary of chondrules and matrix indicates that both components are genetically linked and formed together from one common reservoir of solar nebula dust. As such, the isotopic data require that most chondrules formed in the solar nebula and are not a product of protoplanetary impacts. <span class="hlt">Allende</span> chondrules and matrix together with bulk <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> and some iron meteorites (groups IID, IIIF, and IVB) show uniform excesses in 92Mo, 95Mo, and 97Mo that result from the addition of supernova material to the solar nebula region in which these <span class="hlt">carbonaceous</span> meteorites formed. Non-<span class="hlt">carbonaceous</span> meteorites (enstatite and ordinary <span class="hlt">chondrites</span> as well as most iron meteorites) do not contain this material, demonstrating that two distinct Mo isotope reservoirs co-existed in the early solar nebula that remained spatially separated for several million years. This separation was most likely achieved through the formation of the gas giants, which cleared the disk between the inner and outer solar system regions parental to the non-<span class="hlt">carbonaceous</span> and <span class="hlt">carbonaceous</span> meteorites. The Mo isotope</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V53A4841C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V53A4841C"><span id="translatedtitle">Crystallogenesis of Mixed-Valence Fe-Serpentines: Implications for Their Formation during the Aqueous Alteration of <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrites</span>' Parent Body</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Caste, F.; Elmaleh, A.; Abdelmoula, M.; Menguy, N.; Ona-Nguema, G.; Gérard, M.</p> <p>2014-12-01</p> <p>(Fe3+,Fe2+)-bearing serpentines close to the ideal endmember cronstedtite (Fe2+2,Fe3+) (Si, Fe3+) O5 (OH)4, are major components of CM2-type <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>. 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 <span class="hlt">chondrites</span>' 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 <span class="hlt">chondritic</span> environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5556116','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5556116"><span id="translatedtitle">Constraints on chondrule origin from petrology of isotopically characterized chondrules in the <span class="hlt">Allende</span> meteorite</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mcsween, H.Y. Jr.</p> <p>1985-09-01</p> <p>The petrologic and chemical properties of the ferromagnesian chondrules in the <span class="hlt">Allende</span> <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> were examined in terms of the isotopic composition and the correlations between isotopic patterns. Areas of thin sections were studied with a SEM and bulk chemical fractions of 12 constituents were quantified to calculate correlations with petrologic features. A possible correlation between (CaO + Al2O2)/MgO and oxygen isotopes imply the formation of oxygen isotopic compositions in the chondrules by exchanges between isotopically heavy nebular gases and O-16 enriched solids. Different rates of gaseous exchange occurred with the various types of chondrules. Factors which may have controlled the exchanges are discussed. 21 references.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20010045280&hterms=Genetics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DGenetics','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20010045280&hterms=Genetics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DGenetics"><span id="translatedtitle">Cr Isotope Systematics in the Pallasite Eagle Station: Chronology and Evidence for a Genetic Link to <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shukolyukov, A.; Lugmair, G. W.</p> <p>2001-01-01</p> <p>The study of the Mn-53-Cr-53 system in the pallasite Eagle Station has shown that it formed 4557.5 +/- 0.6 Ma ago. The Cr isotopic signature is different from that of the main group pallasites and suggests a genetic link to CV3 <span class="hlt">chondrites</span>. Additional information is contained in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015E%26PSL.432..472B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015E%26PSL.432..472B"><span id="translatedtitle">Formation timescales of CV <span class="hlt">chondrites</span> from component specific Hf-W systematics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Becker, Maike; Hezel, Dominik C.; Schulz, Toni; Elfers, Bo-Magnus; Münker, Carsten</p> <p>2015-12-01</p> <p><span class="hlt">Carbonaceous</span> <span class="hlt">chondrites</span> are an important meteorite group that closely resembles the bulk composition of the solar system. We report the first elemental and isotope dataset for Hf-W in <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> that includes chondrules, matrix, magnetic fractions as well as bulk compositions. Our study focuses on the three CV3 <span class="hlt">chondrites</span>, <span class="hlt">Allende</span>, Vigarano and Bali. Compared to bulk <span class="hlt">chondrites</span>, matrix splits have low Hf/W ratios and ε182W compositions, whereas chondrule splits are characterized by high, but more variable, Hf/W ratios and ε182W compositions. Thus, Hf/W ratios behave complementary between chondrules and matrix in the analysed CV <span class="hlt">chondrites</span>, supporting the view that both components formed from the same parental reservoir. Strong nucleosynthetic effects were observed in most of the analysed CV3 components, especially in matrices and chondrule splits that were found to have large ε183W anomalies of several ε-units. All separates define a rough correlation between initial 182W/184W and 183W/184W ratios, in agreement with theoretical model trends based on calculations for stellar nucleosynthesis. Our results, therefore, indicate a heterogeneous distribution of s- and r-process W isotopes among the different CV3 <span class="hlt">chondrite</span> components, arguing for selective thermal processing of early solar system matter during chondrule formation. After correcting for nucleosynthetic anomalies, chondrules and matrix splits of reduced (Vigarano) as well as oxidised (<span class="hlt">Allende</span>) CV3 <span class="hlt">chondrites</span> define a linear correlation in ε182W vs. 180Hf/184W space, which is interpreted as an isochron, covering an age interval within the first ∼2.6 Ma after solar system formation. As peak metamorphic temperatures for CV3 <span class="hlt">chondrites</span> were well below the 182Hf-182W closure temperature, the resulting isochron within its error most likely defines a common formation interval for all components. The calculated age interval is for the first time based on a combined chondrule-matrix isochron, a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050173926','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050173926"><span id="translatedtitle">I-Xe Dating: The Time Line of Chondrule Formation and Metamorphism in LL <span class="hlt">Chondrites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pravdivtseva, O. V.; Hohenberg, C. M.; Meshik, A. P.</p> <p>2005-01-01</p> <p>Refractory inclusions, considered to be the oldest solids formed in the solar nebula. (4567.2 0.6 Ma) [1], are common in many <span class="hlt">carbonaceous</span> and in some ordinary and enstatite <span class="hlt">chondrites</span>. High-precision Pb- Pb ages for CAI s and chondrules (from different meteorites) suggested that chondrule formation appeared to have started about 2 Ma later than that of CAIs [1]. However, recent 26Al/26Mg data suggest simultaneous formation of CAI s and chondrules in <span class="hlt">Allende</span> [2]. The I-Xe ages of CAI s in <span class="hlt">Allende</span> are about 2 Ma younger than the I-Xe ages of <span class="hlt">Allende</span> chondrules [3] but, like all chronometers, the I-Xe system records closure time of its particular host phase. In the case of <span class="hlt">Allende</span> CAI s, the major iodine-bearing phase is sodalite, a secondary phase presumably formed by aqueous alteration, so I-Xe reflects the post-formational processes in these objects. In chondrules the iodine host phases vary and can reflect formation and/or alteration but, to put chondrule ages on a quantative basis, some problems should first be addressed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040056000&hterms=System+Solar&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DSystem%2BSolar','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040056000&hterms=System+Solar&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DSystem%2BSolar"><span id="translatedtitle">Oxygen Isotopes in Early Solar System Materials: A Perspective Based on Microbeam Analyses of Chondrules from CV <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, R. H.; Leshin, L. A.; Guan, Y.</p> <p>2004-01-01</p> <p>Some of the biggest challenges to understanding the early history of the solar system include determining the distribution of oxygen isotopes amongst materials that existed in the solar nebula, and interpreting the processes that might have resulted in the observed isotopic distributions. Oxygen isotope ratios in any individual mineral grain from a <span class="hlt">chondritic</span> meteorite may be the cumulative product of a variety of processes, including stellar nucleosynthetic events, gas/solid interactions in the molecular cloud, mixing of independent isotopic reservoirs in the nebula, mass-independent processing in the nebula, and mass-dependent fractionation effects in various environments. It is not possible to unravel this complex isotopic record unless the distribution of oxygen isotope ratios in <span class="hlt">chondritic</span> materials is fully understood.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20050165543&hterms=coagulation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dcoagulation','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20050165543&hterms=coagulation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dcoagulation"><span id="translatedtitle"><span class="hlt">Chondrites</span> and the Protoplanetary Disk, Part 2</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p>Contents include the following: On the Dynamical Evolution of a Nebula and Its Effect on Dust Coagulation and the Formation of Centimeter-sized Particles. The Mineralogy and Grain Properties of the Disk Surfaces in Three Herbig Ae/Be Stars. Astrophysical Observations of Disk Evolution Around Solar Mass Stars. The Systematic Petrology of <span class="hlt">Chondrites</span>: A Consistent Approach to Assist Classification and Interpretation. Understanding Our Origins: Formation of Sun-like Stars in H II Region Environments. Chondrule Crystallization Experiments. Formation of SiO2-rich Chondrules by Fractional Condensation. Refractory Forsterites from Murchison (CM2) and Yamato 81020 (CO3.0) <span class="hlt">Chondrites</span>: Cathodoluminescence, Chemical Compositions and Oxygen Isotopes. Apparent I-Xe Cooling Rates of Chondrules Compared with Silicates from the Colomera Iron Meteorite. Chondrule Formation in Planetesimal Bow Shocks: Physical Processes in the Near Vicinity of the Planetesimal. Genetic Relationships Between Chondrules, Rims and Matrix. <span class="hlt">Chondrite</span> Fractionation was Cosmochemical; Chondrule Fractionation was Geochemical. Chondrule Formation and Accretion of <span class="hlt">Chondrite</span> Parent Bodies: Environmental Constraints. Amoeboid Olivine Aggregates from the Semarkona LL3.0 <span class="hlt">Chondrite</span>. The Evolution of Solids in Proto-Planetary Disks. New Nickel Vapor Pressure Measurements: Possible Implications for Nebular Condensates. Chemical, Mineralogical and Isotopic Properties of Chondrules: Clues to Their Origin. Maximal Size of Chondrules in Shock-Wave Heating Model: Stripping of Liquid Surface in Hypersonic Rarefied Gas Flow. The Nature and Origin of Interplanetary Dust: High Temperature Components. Refractory Relic Components in Chondrules from Ordinary <span class="hlt">Chondrites</span>. Constraints on the Origin of Chondrules and CAIs from Short-lived and Long-lived Radionuclides. The Genetic Relationship Between Refractory Inclusions and Chondrules. Contemporaneous Chondrule Formation Between Ordinary and <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrites</span>. Chondrules and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.110..190M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.110..190M"><span id="translatedtitle">Heterogeneous distribution of 26Al at the birth of the Solar System: Evidence from corundum-bearing refractory inclusions in <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Makide, Kentaro; Nagashima, Kazuhide; Krot, Alexander N.; Huss, Gary R.; Hutcheon, Ian D.; Hellebrand, Eric; Petaev, Michail I.</p> <p>2013-06-01</p> <p>We report on the mineralogy, petrology, and in situ oxygen- and magnesium-isotope measurements using secondary ion mass spectrometry of 10 corundum-bearing calcium-aluminum-rich inclusions (CAIs) from the Adelaide (ungrouped), Murray and Murchison (CM) <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>. We also measured in situ oxygen-isotope compositions of several isolated corundum grains in the matrices of Murray and Murchison. Most of the corundum-bearing objects studied are uniformly 16O-rich [Δ17O values range from -17‰ to -28‰ (2σ = ±2.5‰) (Δ17Oavr = -23 ± 5‰)], suggesting that they formed in a 16O-rich gas of approximately solar composition and largely avoided subsequent thermal processing in an 16O-poor gaseous reservoir. There is a large spread of the initial 26Al/27Al ratio [(26Al/27Al)0] in the corundum-bearing CAIs. Two Adelaide CAIs show no resolvable excess of radiogenic 26Mg (δ26Mg∗): the inferred (26Al/27Al)0 are (0.6 ± 2.0) × 10-6 and (-0.9 ± 1.2) × 10-6, respectively. Slopes of the model 26Al-26Mg isochrons in five CAIs from Murray and Murchison are (4.4 ± 0.2) × 10-5, (3.3 ± 0.3) × 10-5, (4.1 ± 0.3) × 10-5, (3.9 ± 0.4) × 10-5, and (4.0 ± 2.0) × 10-6, respectively. These values are lower than the canonical (26Al/27Al)0 ratio of (5.23 ± 0.13) × 10-5 inferred from the whole-rock magnesium-isotope measurements of the CV CAIs, but similar to the (26Al/27Al)0 ratio of (4.1 ± 0.2) × 10-5 in the corundum-bearing CAI F5 from Murray. Five other previously studied corundum-bearing CAIs from Acfer 094 (ungrouped) and CM <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> showed no resolvable δ26Mg∗. We conclude that the corundum-bearing CAIs, as well as the solar corundum grains from matrices and acid-resistant residues of unequilibrated ordinary and <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>, recorded heterogeneous distribution of 26Al in the Solar System during an epoch of CAI formation. The 26Al-rich and 26Al-poor corundum-bearing CAIs and solar corundum grains represent different</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140010587','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140010587"><span id="translatedtitle">Search for Fluid Inclusions in a <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrite</span> Using a New X-Ray Micro-Tomography Technique Combined with FIB Sampling</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Tsuchiyama, A.; Miyake, A.; Zolensky, M. E.; Uesugi, K.; Nakano, T.; Takeuchi, A.; Suzuki, Y.; Yoshida, K.</p> <p>2014-01-01</p> <p>Early solar system aqueous fluids are preserved in some H <span class="hlt">chondrites</span> as aqueous fluid inclusions in halite (e.g., [1]). Although potential fluid inclusions are also expected in <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> [2], they have not been surely confirmed. In order to search for these fluid inclusions, we have developped a new X-ray micro-tomography technique combined with FIB sampling and applied this techniqu to a carbanaceous <span class="hlt">chondrite</span>. Experimental: A polished thin section of Sutter's Mill meteorite (CM) was observed with an optical microscope and FE-SEM (JEOL 7001F) for chosing mineral grains of carbonates (mainly calcite) and sulfides (FeS and ZnS) 20-50 microns in typical size, which may have aqueous fluid inclusions. Then, a "house" similar to a cube with a roof (20-30 microns in size) is sampled from the mineral grain by using FIB (FEI Quanta 200 3DS). Then, the house was atached to a thin W-needle by FIB and imaged by a SR-based imaging microtomography system with a Fresnel zone plate at beamline BL47XU, SPring-8, Japan. One sample was imaged at two X-ray energies, 7 and 8 keV, to identify mineral phases (dual-enegy microtomography: [3]). The size of voxel (pixel in 3D) was 50-80 nm, which gave the effective spatial resolution of approx. 200 nm. A terrestrial quartz sample with an aqueous fluid inclusion with a bubble was also examined as a test sample by the same method. Results and discussion: A fluid inclusion of 5-8 microns in quartz was clearly identified in a CT image. A bubble of approx. 4 microns was also identified as refraction contrast although the X-ray absorption difference between fluid and bubble is small. Volumes of the fluid and bubble were obtained from the 3D CT images. Fourteen grains of calcite, two grains of iron sulfide and one grain of (Zn,Fe)S were examined. Ten calcite, one iron sulfide and one (Zn,Fe)S grains have inclusions >1 micron in size (the maximum: approx. 5 microns). The shapes are spherical or irregular. Tiny inclusions (<1 micron</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.187..237L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.187..237L"><span id="translatedtitle">Elephant Moraine 96029, a very mildly aqueously altered and heated CM <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span>: Implications for the drivers of parent body processing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Martin R.; Lindgren, Paula; King, Ashley J.; Greenwood, Richard C.; Franchi, Ian A.; Sparkes, Robert</p> <p>2016-08-01</p> <p>Elephant Moraine (EET) 96029 is a CM <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> 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 <span class="hlt">chondrites</span>, 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20070019370&hterms=chromium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dchromium','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20070019370&hterms=chromium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dchromium"><span id="translatedtitle">Early Archean Spherule Beds: Chromium Isotopes Confirm Origin through Multiple Impacts of Projectiles of <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrite</span> Type: Comment and Reply</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kyte, Frank T.</p> <p>2003-01-01</p> <p>This is a exchange in the form of a comment and a reply in regards to an earlier article. The authors of the original article, consider it likely that virtually all of the projectile will condense with the silicate fraction, resulting in very little platinum group element fractionation in the final ejecta deposit. Further, we find no evidence in the commentator's, (i.e., Glikson), comment to support vapor fractionation. We note that the Pd/Ir ratios of published data on 2.56 Ga Hamersley Basin spherules are all greater than in <span class="hlt">chondrites</span>, contrary to the assertion by Glikson. This is consistent with relatively high Pd concentrations (and Pd/Ir ratios) in crustal rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940016337&hterms=synthesized+crystals&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dsynthesized%2Bcrystals','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940016337&hterms=synthesized+crystals&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dsynthesized%2Bcrystals"><span id="translatedtitle">Hydrothermal alteration experiments of olivine with varying Fe contents: An attempt to simulate aqueous alteration of the <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Takatori, Koichi; Tomeoka, Kazushige; Tsukimura, Katsuhiro; Takeda, Hiroshi</p> <p>1993-01-01</p> <p>Hydrothermal alteration experiments of olivine powder with several Fe/Mg ratios were carried out under acidic and neutral conditions, and transition electron microscopy (TEM) observations were made on the run products. Well-developed tubular crystals of serpentine (chrysotile) were synthesized from Fo100 under both acidic and neutral conditions, and from Fo92 and Fo80 under acidic condition. Abundance and size of chrysotile apparenlty dependent on the Fe contents of olivine, i.e. with increasing Fe contents, less and smaller chrysotile was formed. Acidity of the solution plays an important role for the formation of chrysotile. Platy and fibrous crystals of phyllosilicate, probably serpentine, were obtained from Fo50 and Fo20 treated under acidic condition, which are most similar to the phyllosilicates in the CI and CM <span class="hlt">chondrites</span>. Framboidal aggregates of Fe-rich grains (presumably Fe-hydroxide) were formed from Fa100 and Fo20, but no phyllosilicate was formed from Fa100.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950051518&hterms=cr2&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dcr2','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950051518&hterms=cr2&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dcr2"><span id="translatedtitle">Origin of dark clasts in the Acfer 059/El Djouf 001 CR2 <span class="hlt">chondrite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Endreb, M.; Keil, K.; Bischoff, A.; Speitel, B.; Clayton, R. N.; Mayeda, T. K.</p> <p>1994-01-01</p> <p>The ten specimens of the paired Acfer 059/El Djouf 001 CR2 <span class="hlt">chondrite</span> contain abundant lithic fragments which we refer to as dark clasts. Petrological and mineralogical studies reveal that they are not related to the CR2 host meteorite but are similar to dark clasts in other CR2 <span class="hlt">chondrites</span>. Dark clasts consist of chondrule and mineral fragments, phyllosilicate fragments and clusters, magnetite, sulfides and accessory phases, embedded into a very fine-grained, phyllosilicate-rich matrix. Magnetite has morphologies known from CI <span class="hlt">chondrites</span>: spherules, framboids and platelets. Average abundances of major elements in the dark clasts are mostly in the range of both CR and CV <span class="hlt">chondrites</span>, but strong depletions in Na and S are apparent. Oxygen isotopic compositions of two dark clasts suggest relationships to type 3 <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> and dark inclusions in <span class="hlt">Allende</span>. The dark clasts are clearly different in texture and mineralogical compositions from the host matrix of Acfer 059/El Djouf 001. Therefore, these dark clasts are xenoliths and are quite unlike the Acfer 059/El Djouf 001 CR2 host meteorite. We suggest that dark clasts accreted at the same time with all other components during the formation of Acfer 059/El Djouf 001 whole rock.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5596335','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5596335"><span id="translatedtitle">Fayalite-rich rims, veins, and halos around and in forsteritic olivines in CAIs and chondrules in <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>: Types, compositional profiles and constraints of their formation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hua, X.; Adam, J.; Palme, H.; Goresy, A. E. )</p> <p>1988-06-01</p> <p>Fayalite-rich rims, veins, and halos around and in forsteritic olivines are a wide-spread phenomenon in chondrules, Ca, Al-rich inclusions (CAIs), and single grains in <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>. The presence of fayalite rod-like crystals and laths in rims, veins, in wall of pores, and as fluffy network bridging neighboring olivines, pyroxenes, feldspars, etc. is strongly suggestive that the fayalitic olivine was formed by condensation presumably from the solar nebula gas. The formation of the fayalitic olivine was probably caused by an increase in the H{sub 2}O/H{sub 2} ratio (to a ratio between 0.1-1) subsequent to condensation of forsterite. At that stage, FeNi inclusions in olivine were also oxidized and fayalitic halos around the metal were then formed Fe diffusion along with addition of SiO{sub 2} from the solar gas or loss of M{sub g}O to the solar gas. The Fa-rich olivine rims and veins display a narrow compositional variation between Fa{sup 34} and Fa{sup 46}. Subsequent to condensation of Fa-rich olivine and oxidation of FeNi metal, Fe diffused in forsterite. This diffusion was probable enhanced due to the presence of point defects in olivine or the formation of a nonstoichiometric phase analogous to laihunite enriched in Al{sub 2}O{sub 3} and Cr{sub 2}O{sub 3}. However, the presence of Al{sub 2}O{sub 3{minus}} and Cr{sub 2}O{sub 3{minus}} rich discrete domains cannot by excluded. Cooling rates calculated by modeling of the diffusion profiles are indicative of rapid cooling subsequent to the condensation of fayalitic olivines. The authors obtain cooling rates ranging from 2000{degree}/day and 10{degree}C/day at an initial temperature of 1200C{degree} and 900C{degree}, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996M%26PS...31..321H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996M%26PS...31..321H"><span id="translatedtitle">Thermal metamorphism of the C, G, B, and F asteroids seen from the 0.7 micron, 3 micron and UV absorption strengths in comparison with <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hiroi, Takahiro; Zolensky, Michael E.; Pieters, Carlé M.; Lipschutz, Michael E.</p> <p>1996-05-01</p> <p>Thermal metamorphism study of the C, G, B, and F asteroids has been revisited using their UV, visible, NIR, and 3 μm reflectance spectra. High-quality reflectance spectra of seven selected C, G, B, and F asteroids have been compared with spectra for 29 <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>, including thermally-metamorphosed CI/CM meteorites. There are three sets of spectral counterparts, among which 511 Davida and B-7904 are the most similar to each other in terms of both spectral shape and brightness. By comparing the 0.7 μm and 3 μm absorption strengths of 21 C, G, B, and F asteroids and heated Murchison samples, these asteroids have been grouped into three heating-temperature ranges. These correspond to (1) <400 °C: phyllosilicate-rich; (2) 400-600 °C: phyllosilicates transformed to anhydrous silicates; and (3) >600 °C: fully anhydrous. A good correlation between the UV and 3 μm absorption strengths has been confirmed for the C, G, B, and F asteroids and the CI, CM, and CR meteorites. A plot of the UV absorption strength vs. the IRAS diameter for 142 C, G, B, and F asteroids shows that the maximum UV absorption strength decreases as the diameter increases for the asteroids >60 km, with a notable exception, Ceres. These relationships suggest that some of the larger asteroids may be the heated inner portions of once larger bodies and that common CI/CM meteorites may have come from the lost outer portions, which escaped extensive late-stage heating events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFMMR13B1709T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFMMR13B1709T"><span id="translatedtitle">Using ArcGIS for correlating multi-technique micro-spatial analytical data: A case study of early solar system carbonates in a <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span>.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tyra, M. A.; Brearley, A.</p> <p>2008-12-01</p> <p>Meteorites are rare and valuable extraterrestrial materials that are typically studied using multiple micro- and nanoanalytical techniques such as SEM, EPMA, SIMS, SXRF and FIB/TEM. Each of these techniques is frequently used to study the same thin section in detail. Management of the significant amounts of spatial and analytical data obtained at various scales from the millimeter to nanometer-scales over a ~3 cm2 thin section is a major challenge. Here we demonstrate that a geographical information system, or GIS, typically used for much larger scale spatial data manipulation can be used equally successfully to store and analyze spatially correlated petrographic and mineralogical data. The advantages of using GIS techniques at the microscale are multifold. For example, querying various types of analytical data can be made with ease by the researcher. Furthermore, posted geodatabase meteorite data can be analyzed by other researchers concurrently or years after a project has been completed. This facilitates comparisons between other meteorite samples of differing classification, within a classification, or samples of the same meteorite. Here we demonstrate the application of a GIS to a correlate data obtained from a thin section of the ALH84051 CM1 meteorite, a <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> that has experienced extensive aqueous alteration. Mosaiced images obtained by optical microscopy of the entire thin section are used as a base "map" and are overlain with SEM and CL images obtained at different magnifications, compositional data (EPMA), and other spatial data. The overall objectives of this study are to gain insights into the processes of aqueous alteration using carbonate mineral assemblages, morphology, abundance, and chemical composition (major, minor and trace elements). Future work will also include Mn-Cr chronometry and oxygen isotopic analysis using SIMS to examine carbonate emplacement and fluid evolution within the meteorite parent body.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70118348','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70118348"><span id="translatedtitle">Formation of replicating saponite from a gel in the presence of oxalate: implications for the formation of clay minerals in <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> and the origin of life</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Schumann, Dirk; Hartman, Hyman; Eberl, Dennis D.; Sears, S. Kelly; Hesse, Reinhard; Vali, Hojatollah</p> <p>2012-01-01</p> <p>The potential role of clay minerals in the abiotic origin of life has been the subject of ongoing debate for the past several decades. At issue are the clay minerals found in a class of meteorites known as <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>. These clay minerals are the product of aqueous alteration of anhydrous mineral phases, such as olivine and orthopyroxene, that are often present in the chondrules. Moreover, there is a strong correlation in the occurrence of clay minerals and the presence of polar organic molecules. It has been shown in laboratory experiments at low temperature and ambient pressure that polar organic molecules, such as the oxalate found in meteorites, can catalyze the crystallization of clay minerals. In this study, we show that oxalate is a robust catalyst in the crystallization of saponite, an Al- and Mg-rich, trioctahedral 2:1 layer silicate, from a silicate gel at 60°C and ambient pressure. High-resolution transmission electron microscopy analysis of the saponite treated with octadecylammonium (n(C)=18) cations revealed the presence of 2:1 layer structures that have variable interlayer charge. The crystallization of these differently charged 2:1 layer silicates most likely occurred independently. The fact that 2:1 layer silicates with variable charge formed in the same gel has implications for our understanding of the origin of life, as these 2:1 clay minerals most likely replicate by a mechanism of template-catalyzed polymerization and transmit the charge distribution from layer to layer. If polar organic molecules like oxalate can catalyze the formation of clay-mineral crystals, which in turn promote clay microenvironments and provide abundant adsorption sites for other organic molecules present in solution, the interaction among these adsorbed molecules could lead to the polymerization of more complex organic molecules like RNA from nucleotides on early Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22794298','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22794298"><span id="translatedtitle">Formation of replicating saponite from a gel in the presence of oxalate: implications for the formation of clay minerals in <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> and the origin of life.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schumann, Dirk; Hartman, Hyman; Eberl, Dennis D; Sears, S Kelly; Hesse, Reinhard; Vali, Hojatollah</p> <p>2012-06-01</p> <p>The potential role of clay minerals in the abiotic origin of life has been the subject of ongoing debate for the past several decades. At issue are the clay minerals found in a class of meteorites known as <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>. These clay minerals are the product of aqueous alteration of anhydrous mineral phases, such as olivine and orthopyroxene, that are often present in the chondrules. Moreover, there is a strong correlation in the occurrence of clay minerals and the presence of polar organic molecules. It has been shown in laboratory experiments at low temperature and ambient pressure that polar organic molecules, such as the oxalate found in meteorites, can catalyze the crystallization of clay minerals. In this study, we show that oxalate is a robust catalyst in the crystallization of saponite, an Al- and Mg-rich, trioctahedral 2:1 layer silicate, from a silicate gel at 60°C and ambient pressure. High-resolution transmission electron microscopy analysis of the saponite treated with octadecylammonium (n(C)=18) cations revealed the presence of 2:1 layer structures that have variable interlayer charge. The crystallization of these differently charged 2:1 layer silicates most likely occurred independently. The fact that 2:1 layer silicates with variable charge formed in the same gel has implications for our understanding of the origin of life, as these 2:1 clay minerals most likely replicate by a mechanism of template-catalyzed polymerization and transmit the charge distribution from layer to layer. If polar organic molecules like oxalate can catalyze the formation of clay-mineral crystals, which in turn promote clay microenvironments and provide abundant adsorption sites for other organic molecules present in solution, the interaction among these adsorbed molecules could lead to the polymerization of more complex organic molecules like RNA from nucleotides on early Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeCoA.148..159L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.148..159L"><span id="translatedtitle">The paradox between low shock-stage and evidence for compaction in CM <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> explained by multiple low-intensity impacts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lindgren, Paula; Hanna, Romy D.; Dobson, Katherine J.; Tomkinson, Tim; Lee, Martin R.</p> <p>2015-01-01</p> <p>Petrographic analysis of eight CM <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> (EET 96029, LAP 031166, LON 94101, MET 01072, Murchison, Murray, SCO 06043, QUE 93005) by electron imaging and diffraction, and X-ray computed tomography, reveals that six of them have a petrofabric defined by shock flattened chondrules. With the exception of Murchison, those CMs that have a strong petrofabric also contain open or mineralized fractures, indicating that tensional stresses accompanying the impacts were sufficient to locally exceed the yield strength of the meteorite matrix. The CMs studied span a wide range of petrologic subtypes, and in common with Rubin (2012) we find that the strength of their petrofabrics increases with their degree of aqueous alteration. This correspondence suggests that impacts were responsible for enhancing alteration, probably because the fracture networks they formed tapped fluid reservoirs elsewhere in the parent body. Two meteorites that do not fit this pattern are MET 01072 and Murchison; both have a strong petrofabric but are relatively unaltered. In the case of MET 01072, impact deformation is likely to have postdated parent body aqueous activity. The same may also be true for Murchison, but as this meteorite also lacks fractures and veins, its chondrules were most likely flattened by multiple low intensity impacts. Multiphase deformation of Murchison is also revealed by the microstructures of calcite grains, and chondrule-defined petrofabrics as revealed by X-ray computed tomography. The contradiction between the commonplace evidence for impact-deformation of CMs and their low shock stages (most belong to S1) can be explained by most if not all having been exposed to multiple low intensity (i.e., <5 GPa) shock events. Aqueous alteration was enhanced by those impacts that were of sufficient intensity to open high permeability fracture networks that could connect to fluid reservoirs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22794298','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22794298"><span id="translatedtitle">Formation of replicating saponite from a gel in the presence of oxalate: implications for the formation of clay minerals in <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> and the origin of life.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schumann, Dirk; Hartman, Hyman; Eberl, Dennis D; Sears, S Kelly; Hesse, Reinhard; Vali, Hojatollah</p> <p>2012-06-01</p> <p>The potential role of clay minerals in the abiotic origin of life has been the subject of ongoing debate for the past several decades. At issue are the clay minerals found in a class of meteorites known as <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>. These clay minerals are the product of aqueous alteration of anhydrous mineral phases, such as olivine and orthopyroxene, that are often present in the chondrules. Moreover, there is a strong correlation in the occurrence of clay minerals and the presence of polar organic molecules. It has been shown in laboratory experiments at low temperature and ambient pressure that polar organic molecules, such as the oxalate found in meteorites, can catalyze the crystallization of clay minerals. In this study, we show that oxalate is a robust catalyst in the crystallization of saponite, an Al- and Mg-rich, trioctahedral 2:1 layer silicate, from a silicate gel at 60°C and ambient pressure. High-resolution transmission electron microscopy analysis of the saponite treated with octadecylammonium (n(C)=18) cations revealed the presence of 2:1 layer structures that have variable interlayer charge. The crystallization of these differently charged 2:1 layer silicates most likely occurred independently. The fact that 2:1 layer silicates with variable charge formed in the same gel has implications for our understanding of the origin of life, as these 2:1 clay minerals most likely replicate by a mechanism of template-catalyzed polymerization and transmit the charge distribution from layer to layer. If polar organic molecules like oxalate can catalyze the formation of clay-mineral crystals, which in turn promote clay microenvironments and provide abundant adsorption sites for other organic molecules present in solution, the interaction among these adsorbed molecules could lead to the polymerization of more complex organic molecules like RNA from nucleotides on early Earth. PMID:22794298</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070003758','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070003758"><span id="translatedtitle">The Origin of Dark Inclusions in <span class="hlt">Allende</span>: New Evidence from Lithium Isotopes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sephton, Mark A.; James, Rachael H.; Zolensky, Michael E.</p> <p>2006-01-01</p> <p>Aqueous and thermal processing of primordial material occurred prior to and during planet formation in the early solar system. A record of how solid materials were altered at this time is present in the <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>, which are naturally delivered fragments of primitive asteroids. It has been proposed that some materials, such as the clasts termed dark inclusions found in type III <span class="hlt">chondrites</span>, suggest a sequence of aqueous and thermal events. Lithium isotopes (Li-6 and Li-7) can reveal the role of liquid water in dark inclusion history. During aqueous alteration, Li-7 passes preferentially into solution leaving Li-6 behind in the solid phase and, consequently, any relatively extended periods of interaction with Li-7-rich fluids would have left the dark inclusions enriched in the heavier isotope when compared to the meteorite as a whole. Our analyses of lithium isotopes in <span class="hlt">Allende</span> and its dark inclusions reveal marked isotopic homogeneity and no evidence of greater levels of aqueous alteration in dark inclusion history.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950029328&hterms=kr&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dkr','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950029328&hterms=kr&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dkr"><span id="translatedtitle">Carbon, nitrogen, magnesium, silicon, and titanium isotopic compositions of single interstellar silicon carbide grains from the Murchison <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hoppe, Peter; Amari, Sachiko; Zinner, Ernst; Ireland, Trevor; Lewis, Roy S.</p> <p>1994-01-01</p> <p>Seven hundred and twenty SiC grains from the Murchison CM2 <span class="hlt">chondrite</span>, ranging in size from 1 to 10 micrometers, were analyzed by ion microprobe mass spectrometry for their C-isotopic compositions. Subsets of the grains were also analyzed for N (450 grains), Si (183 grains), Mg (179 grains), and Ti (28 grains) isotopes. These results are compared with previous measurements on 41 larger SiC grains (up to 15 x 26 micrometers) from a different sample of Murchison analyzed by Virag et al. (1992) and Ireland, Zinner, & Amari (1991a). All grains of the present study are isotopically anomalous with C-12/C-13 ratios ranging from 0.022 to 28.4 x solar, N-14/N-15 ratios from 0.046 to 30 x solar, Si-29/Si-28 from 0.54 to 1.20 x solar, Si-30/Si-28 from 0.42 to 1.14 x solar, Ti-49/Ti-48 from 0.96 to 1.95 x solar, and Ti-50/Ti-48 from 0.94 to 1.39 x solar. Many grains have large Mg-26 excesses from the decay of Al-26 with inferred Al-26/Al-27 ratios ranging up to 0.61, or 12,200 x the ratio of 5 x 10(exp -5) inferred for the early solar system. Several groups can be distinguished among the SiC grains. Most of the grains have C-13 and N-14 excesses, and their Si isotopic compositions (mostly excesses in Si-29 and Si-30) plot close to a slope 1.34 line on a Delta Si-29/Si-28 versus Delta Si-30/Si-28 three-isotope plot. Grains with small C-12/C-13 ratios (less than 10) tend to have smaller or no N-14 excesses and high Al-26/Al-27 ratios (up to 0.01). Grains with C-12/C-13 greater than 150 fall into two groups: grains X have N-15 excesses and Si-29 and Si-30 deficits and the highest (0.1 to 0.6) Al-26/Al-27 ratios; grains Y have N-14 excesses and plot on a slope 0.35 line on a Si three-isotope plot. In addition, large SiC grains of the Virag et al. (1992) study fall into three-distinct clusters according to their C-, Si-, and Ti-isotopic compositions. The isotopic diversity of the grains and the clustering of their isotopic compositions imply distinct and multiple stellar sources</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70026103','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70026103"><span id="translatedtitle">Highly siderophile elements in <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Horan, M.F.; Walker, R.J.; Morgan, J.W.; Grossman, J.N.; Rubin, A.E.</p> <p>2003-01-01</p> <p>The abundances of the highly siderophile elements (HSE), Re, Os, Ir, Ru, Pt and Pd, were determined by isotope dilution mass spectrometry for bulk samples of 13 <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>, 13 ordinary <span class="hlt">chondrites</span> and 9 enstatite <span class="hlt">chondrites</span>. These data are coupled with corresponding 187Re-187Os isotopic data reported by Walker et al. [Geochim. Cosmochim. Acta, 2002] in order to constrain the nature and timing of chemical fractionation relating to these elements in the early solar system. The suite of <span class="hlt">chondrites</span> examined displays considerable variations in absolute abundances of the HSE, and in the ratios of certain HSE. Absolute abundances of the HSE vary by nearly a factor of 80 among the <span class="hlt">chondrite</span> groups, although most vary within a factor of only 2. Variations in concentration largely reflect heterogeneities in the sample aliquants. Different aliquants of the same <span class="hlt">chondrite</span> may contain variable proportions of metal and/or refractory inclusions that are HSE-rich, and sulfides that are HSE-poor. The relatively low concentrations of the HSE in CI1 <span class="hlt">chondrites</span> likely reflect dilution by the presence of volatile components. <span class="hlt">Carbonaceous</span> <span class="hlt">chondrites</span> have Re/Os ratios that are, on average, approximately 8% lower than ratios for ordinary and enstatite <span class="hlt">chondrites</span>. This is also reflected in 187Os/188Os ratios that are approximately 3% lower for <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> than for ordinary and enstatite <span class="hlt">chondrites</span>. Given the similarly refractory natures of Re and Os, this fractionation may have occurred within a narrow range of high temperatures, during condensation of these elements from the solar nebula. Superimposed on this major fractionation are more modest movements of Re or Os that occurred within the last 0-2 Ga, as indicated by minor open-system behavior of the Re-Os isotope systematics of some <span class="hlt">chondrites</span>. The relative abundances of other HSE can also be used to discriminate among the major classes of <span class="hlt">chondrites</span>. For example, in comparison to the enstatite <span class="hlt">chondrites</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015M%26PS...50.1529C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015M%26PS...50.1529C"><span id="translatedtitle">Fe-Mg interdiffusion profiles in rimmed forsterite grains in the <span class="hlt">Allende</span> matrix: Time-temperature constraints for the parent body metamorphism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cuvillier, Priscille; Leroux, Hugues; Jacob, Damien; Hirel, Pierre</p> <p>2015-09-01</p> <p>The <span class="hlt">Allende</span> matrix is dominated by micron-sized lath-shaped fayalitic olivine grains with a narrow compositional range (Fa40-50). Fayalitic olivines also occur as rims around forsterite grains in chondrules and isolated forsterite fragments in the matrix or as veins cross-cutting the grains. <span class="hlt">Allende</span> is a type 3 CV <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> having experienced a moderate thermal metamorphism. There is therefore a strong chemical disequilibrium between the large forsterite grains and the fayalite-rich fine-grained matrix. Chemical gradients at interfaces are poorly developed and thus not accessible using conventional techniques. Here, we used analytical transmission electron microscopy to study the microstructure of the fayalite-rich matrix grains and interfaces with forsterite fragments. We confirm that fayalitic grains in the matrix and fayalitic rims around forsterite fragments have the same properties, suggesting a common origin after the accretion of the parent body of <span class="hlt">Allende</span>. Composition profiles at the rim/forsterite interfaces exhibit a plateau in the rim (typically Fa45), a compositional jump of 10 Fa% at the interface, and a concentration gradient in the forsterite grain. Whatever the studied forsterite grain or whatever the nature of the interface, the Fe-Mg profiles in forsterite grains have the same length of about 1.5 μm. This strongly suggests that the composition profiles were formed by solid-state diffusion during the thermal metamorphism episode. Time-temperature couples associated with the diffusion process during thermal metamorphism are deduced from profile modeling. Considering the uncertainties on the diffusion coefficient value, we found that the peak temperature in <span class="hlt">Allende</span> is ranging from 425 to 505 °C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19990087893&hterms=onion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Donion','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19990087893&hterms=onion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Donion"><span id="translatedtitle">Fullerenes in <span class="hlt">Allende</span> Meteorite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Becker, L.; Bada, J. L.; Winans, R. E.; Bunch, T. E.</p> <p>1994-01-01</p> <p>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 <span class="hlt">Allende</span> meteorites, the <span class="hlt">Allende</span> 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 <span class="hlt">Allende</span> meteorite. In addition to fullerenes, we detected many polycyclic aromatic hydrocarbons (PAHs) in the <span class="hlt">Allende</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016DPS....4852501D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016DPS....4852501D"><span id="translatedtitle">A combined FE-SEM/EDS and μ-IR analysis of <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrites</span>, analogue of the next returned asteroid samples</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dirri, Fabrizio; Palomba, Ernesto; Ferrari, Marco; Longobardo, Andrea; Rotundi, Alessandra</p> <p>2016-10-01</p> <p>A combined method for the analysis of extraterrestrial samples returned by spacecrafts foresees two different analytical techniques: Field Emission-Scanning Electron Microscope with Energy Dispersive Spectroscopy (FE-SEM/EDS) and Infrared μ-spectroscopy (μ-IR). These are non-destructive analytical techniques that allow obtaining mineral and organic information of the samples: μ-IR spectroscopy is able to provide thermal maps of selected area, whereas FE-SEM/EDS microscopy provides information on sample morphology and chemical composition. The combined results provide a complete overview of the sample mineralogy.In the past, different types of analysis were performed in order to characterise returned asteroid and cometary samples, and meteorites [e.g. 1,2,3]. Waiting for the analyses of the samples to be returned from primitive asteroids targets by Hayabusa 2 and Osiris Rex missions [4,5], we applied the combined FE-SEM/EDS and μ-IR techniques to <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrites</span> (CC) meteorites as possible analogues. In particular, we selected 3 samples: Murchinson (CM2 group), characterised by small chondrules and refractory inclusions [6]; Orgueil (CI1 group) characterised by the absence of chondrules and refractory inclusion and with a high degree of hydration [7]; NWA2086 (CV3 group) with considerable amount of large mm-size chondrules, many surrounded by igneous rims [8]. A preliminary analysis was performed on the samples using a Stereo Microscope (Leica M205c) equipped with a digital camera in order to select regions of the samples showing a significant mineralogical heterogeneity.[1] Rotundi, A. et al., Meteorit. & Planet. Scie.,49,4,550–575,2014[2] Matrajt, G. et al.,A&A,416,3,983-990,2004[3] Naraoka, H. et al.,Geochem. J.,46,1,61-72,2012[4] Chasley, R. et al.,Icarus,235,5-22,2014[5] Yoshikawa, M. et al., 47th LPSC Abs,2016[6] Cronin, J.R. and Chang, S.,The Chemistry of Life's Origins, 416,209-258,1993[7] Tomeoka K. and Buseck P.R., Geochimica et Cosmochimica</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.121..452L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.121..452L"><span id="translatedtitle">The oxygen isotope evolution of parent body aqueous solutions as recorded by multiple carbonate generations in the Lonewolf Nunataks 94101 CM2 <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, M. R.; Sofe, M. R.; Lindgren, P.; Starkey, N. A.; Franchi, I. A.</p> <p>2013-11-01</p> <p>The CM2 <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008GeCoA..72.6141N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008GeCoA..72.6141N"><span id="translatedtitle">Search for extinct 36Cl: Vigarano CAIs, the Pink Angel from <span class="hlt">Allende</span>, and a Ningqiang chondrule</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nakashima, Daisuke; Ott, Ulrich; Hoppe, Peter; El Goresy, Ahmed</p> <p>2008-12-01</p> <p>We have searched for excesses of 36S derived from the decay of extinct 36Cl in sodalite, a secondary Cl-rich mineral, in Ca-Al-rich inclusions (CAIs) from the Vigarano and <span class="hlt">Allende</span> CV3 <span class="hlt">chondrites</span> and in a chondrule from the Ningqiang <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span>. The presence of sodalite in two CAIs from Vigarano and its absence from surrounding CAI fragments suggests sodalite formation after CAI fragmentation. As for sodalite in the <span class="hlt">Allende</span> Pink Angel CAI, oxygen isotopic compositions have been interpreted as indicative of high temperature interactions, thus suggesting formation prior to accretion to the parent body, probably in a nebular setting. Sodalite in the Ningqiang chondrule is considered to have formed via alkali-Ca exchange, which is believed to have occurred before accretion to the parent body. Sodalites in the Vigarano CAIs and in the Ningqiang chondrule show no clear evidence for the presence of radiogenic 36S. The inferred 2 σ upper limits for 36Cl/ 35Cl at the time of sodalite formation are 1.6 × 10 -6 (Vigarano CAIs) and 3.3 × 10 -6 (Ningqiang chondrule), respectively. In the Pink Angel CAI sodalite exhibits small 36S excesses which weakly correlate with 35Cl/ 34S ratios. The inferred 36Cl/ 35Cl ratio of (1.8 ± 2.2) × 10 -6 (2 σ error) is lower than that found by Hsu et al. [Hsu, W., Guan, Y., Leshin, L. A., Ushikubo, T. and Wasserburg, G. J. (2006) A late episode of irradiation in the early solar system: Evidence from extinct 36Cl and 26Al in meteorites. Astrophys. J. 640, 525-529], thus indicative of heterogeneous distribution of 36Cl in this CAI. Spallation reactions induced by energetic particles from the young Sun are suggested for the origin of 36Cl, similar to the case of 10Be. While 10Be appears to be present in roughly equal abundance in all studied CAIs, our study indicates the level of 36Cl abundances to be variable so that there seems to be no simple relationship between 10Be and 36Cl. This would be expected if trapped cosmic rays rather</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993Metic..28Q.373J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993Metic..28Q.373J"><span id="translatedtitle">Fractionation of Volatile Elements by Heating of Solid <span class="hlt">Allende</span>: Implications for the Source Material of Earth, Moon, and the Eucrite Parent Body</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jochum, K. P.; Palme, H.</p> <p>1993-07-01</p> <p>. Nearly-CI-<span class="hlt">chondritic</span> Sn/Pb ratios are observed in <span class="hlt">Allende</span> and other <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>. Evaporation from a solid leads to a severe increase in this ratio. Similarly, Rb/Cs ratios (about 12) are approximately CI-like in all groups of <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>, perhaps reflecting the inability of nebular processes to fractionate these ratios. In contrast, terrestrial, lunar, and eucritic rocks have much higher Rb/Cs ratios [5]. As volatile loss from molten magmas is excluded [2], their low Cs contents must be characteristic of the parent material. This may exclude <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> as source materials of eucrites, the Earth, and the Moon. The low Cs in planetary precursor materials may have been produced by secondary heating of small fragments of solid matter at subsolidus temperatures before final accretion. Equilibrated <span class="hlt">chondrites</span> also show high Rb/Cs ratios, perhaps indicating mobilization of Cs at metamorphic temperatures. References: [1] Palme H. et al. (1988) in Meteorites and the Early Solar System, 436-461, Univ. of Arizona. [2] Humayan M. and Clayton R. N. (1993) LPSC XXIV, 685-686. [3] Davis A. M. et al. (1990) Nature, 347, 655-658. [4] Wulf A. V. and Palme H. (1991) LPSC XXII, 1527-1528. [5] McDonough W. F. et al. (1992) GCA, 56, 1001-1012. Figure 1 appears here in the hard copy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014M%26PS...49..812F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014M%26PS...49..812F"><span id="translatedtitle">Hydrothermal origin of hexagonal CaAl2Si2O8 (dmisteinbergite) in a compact type A CAI from the Northwest Africa 2086 CV3 <span class="hlt">chondrite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fintor, Krisztian; Park, Changkun; Nagy, Szabolcs; Pál-Molnár, Elemér; Krot, Alexander N.</p> <p>2014-05-01</p> <p>We report an occurrence of hexagonal CaAl2Si2O8 (dmisteinbergite) in a compact type A calcium-aluminum-rich inclusion (CAI) from the CV3 (Vigarano-like) <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> Northwest Africa 2086. Dmisteinbergite occurs as approximately 10 μm long and few micrometer-thick lath-shaped crystal aggregates in altered parts of the CAI, and is associated with secondary nepheline, sodalite, Ti-poor Al-diopside, grossular, and Fe-rich spinel. Spinel is the only primary CAI mineral that retained its original O-isotope composition (Δ17O ~ -24‰); Δ17O values of melilite, perovskite, and Al,Ti-diopside range from -3 to -11‰, suggesting postcrystallization isotope exchange. Dmisteinbergite, anorthite, Ti-poor Al-diopside, and ferroan olivine have 16O-poor compositions (Δ17O ~ -3‰). We infer that dmisteinbergite, together with the other secondary minerals, formed by replacement of melilite as a result of fluid-assisted thermal metamorphism experienced by the CV <span class="hlt">chondrite</span> parent asteroid. Based on the textural appearance of dmisteinbergite in NWA 2086 and petrographic observations of altered CAIs from the <span class="hlt">Allende</span> meteorite, we suggest that dmisteinbergite is a common secondary mineral in CAIs from the oxidized <span class="hlt">Allende</span>-like CV3 <span class="hlt">chondrites</span> that has been previously misidentified as a secondary anorthite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19900043792&hterms=American+Museum+of+Natural+History&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3D%2528%2528%2528%2528American%2BMuseum%2529%2Bof%2529%2BNatural%2529%2BHistory%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19900043792&hterms=American+Museum+of+Natural+History&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3D%2528%2528%2528%2528American%2BMuseum%2529%2Bof%2529%2BNatural%2529%2BHistory%2529"><span id="translatedtitle">Dark inclusions in <span class="hlt">Allende</span>, Leoville, and Vigarano - Evidence for nebular oxidation of CV3 constituents</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Johnson, Craig A.; Prinz, Martin; Weisberg, Michael K.; Clayton, Robert N.; Mayeda, Toshiko K.</p> <p>1990-01-01</p> <p>The origin and the history of dark inclusions (DIs) are investigated using petrologic, chemical, and oxygen isotopic data on ten DI samples from <span class="hlt">Allende</span>, Leoville, and Vigarano. These data indicate that the DIs of the Leoville and Vigarano are closely similar to those of <span class="hlt">Allende</span>. The inclusions appear to be fragments of CV3 parent bodies which were processed to different degrees prior to their incorporation as clasts into the <span class="hlt">Allende</span>, Leoville, and Vigarano <span class="hlt">chondrites</span>. The processing homogenized the olivine compositions, presumably through heating, and also involved oxygen exchange with O-16-poorer surroundings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940016385&hterms=MAKEUP&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DMAKEUP','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940016385&hterms=MAKEUP&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DMAKEUP"><span id="translatedtitle">Magnetic record in <span class="hlt">chondrite</span> meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wasilewski, P. J.; Faris, J. L.; Obryan, M. V.</p> <p>1993-01-01</p> <p>What we know about the magnetic record in <span class="hlt">chondrite</span> meteorites based on new data and previously published results is summarized. Strips from thin slabs of <span class="hlt">chondrite</span> meteorites were cut into near cubical subsamples (several mm on edge) numbering approximately 60 to approximately 120 per meteorite. A common orientation was assigned to each subsample from a given meteorite in order to ensure that we could discover the vector makeup of the bulk meteorite. The new data set includes: Shaw (L7), Roy (L5/6), Claytonville (L5), Plainview (H5), Etter (H5), Leoville (C3V), and <span class="hlt">Allende</span> (C3V). In addition to these new results, literature data of sufficient detail, e.g. Bjurbole (L4), ALH769 (L6), Abee (E4), <span class="hlt">Allende</span> (C3V), and Olivenza (L5), is considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19790034584&hterms=metamorphism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dmetamorphism','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19790034584&hterms=metamorphism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dmetamorphism"><span id="translatedtitle">Volatile elements in <span class="hlt">chondrites</span> - Metamorphism or nebular fractionation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Takahashi, H.; Gros, J.; Higuchi, H.; Morgan, J. W.; Anders, E.</p> <p>1978-01-01</p> <p>Three of the most highly metamorphosed meteorites of their respective classes, Shaw (LL7), Karoonda (C5), and Coolidge (C4), were analyzed by radiochemical neutron activation analysis for Ag, Au, Bi, Br, Cd, Cs, Ge, In, Ir, Ni, Os, Pd, Rb, Re, Sb, Se, Te, Tl, U, and Zn. Comparison with data by Lipschutz and coworkers (1977) on artificially heated primitive meteorites shows that the natural metamorphism of meteorites cannot have taken place in a system open to volatiles. Shaw, metamorphosed at 1300 C for more than 1 million yr, is less depleted in In, Bi, Ag, Te, Zn, and Tl than Krymka heated at 1000 C for 1 week. Karoonda, metamorphosed at 600 C for many millennia, is less depleted in Bi and Tl than <span class="hlt">Allende</span> heated at 600 C for 1 week. Data on primordial noble gases also show that the volatile-element patterns of ordinary and <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> were established by nebular condensation and changed little, if at all, during metamorphism. For enstatite <span class="hlt">chondrites</span>, the evidence is still incomplete but seems to favor a nebular origin of the volatile pattern.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.189..338L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.189..338L"><span id="translatedtitle">CV and CM <span class="hlt">chondrite</span> impact melts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lunning, Nicole G.; Corrigan, Catherine M.; McSween, Harry Y.; Tenner, Travis J.; Kita, Noriko T.; Bodnar, Robert J.</p> <p>2016-09-01</p> <p>Volatile-rich and typically oxidized <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>, such as CV and CM <span class="hlt">chondrites</span>, potentially respond to impacts differently than do other <span class="hlt">chondritic</span> materials. Understanding impact melting of <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> has been hampered by the dearth of recognized impact melt samples. In this study we identify five <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> impact melt clasts in three host meteorites: a CV3red <span class="hlt">chondrite</span>, a CV3oxA <span class="hlt">chondrite</span>, and a regolithic howardite. The impact melt clasts in these meteorites respectively formed from CV3red <span class="hlt">chondrite</span>, CV3oxA <span class="hlt">chondrite</span>, and CM <span class="hlt">chondrite</span> protoliths. We identified these impact melt clasts and interpreted their precursors based on their texture, mineral chemistry, silicate bulk elemental composition, and in the case of the CM <span class="hlt">chondrite</span> impact melt clast, in situ measurement of oxygen three-isotope signatures in olivine. These impact melts typically contain euhedral-subhedral olivine microphenocrysts, sometimes with relict cores, in glassy groundmasses. Based on petrography and Raman spectroscopy, four of the impact melt clasts exhibit evidence for volatile loss: these melt clasts either contain vesicles or are depleted in H2O relative to their precursors. Volatile loss (i.e., H2O) may have reduced the redox state of the CM <span class="hlt">chondrite</span> impact melt clast. The clasts that formed from the more oxidized precursors (CV3oxA and CM <span class="hlt">chondrites</span>) exhibit phase and bulk silicate elemental compositions consistent with higher intrinsic oxygen fugacities relative to the clast that formed from a more reduced precursor (CV3red <span class="hlt">chondrite</span>). The mineral chemistries and assemblages of the CV and CM <span class="hlt">chondrite</span> impact melt clasts identified here provide a template for recognizing <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> impact melts on the surfaces of asteroids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016LPICo1921.6239S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016LPICo1921.6239S"><span id="translatedtitle">Synchrotron X-Ray Fluorescence Analysis of Trace Elements in Focused Ion Beam Prepared Sections of <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrite</span> Iron Sulfides (CM and CR) and Associated Metal (CR)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Singerling, S. A.; Sutton, S. R.; Lanzirotti, A.; Newville, M.; Brearley, A. J.</p> <p>2016-08-01</p> <p>This study presents data on trace element abundances in CM and CR sulfides and metals. We determined that Ge and Zn were observed to be depleted relative to CI <span class="hlt">chondrite</span> while the more volatile Se was observed to be enriched.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17737315','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17737315"><span id="translatedtitle">Meteorite fail at pueblito de <span class="hlt">allende</span>, chihuahua, Mexico: preliminary information.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>King, E A; Schonfeld, E; Richardson, K A; Eldridge, J S</p> <p>1969-02-28</p> <p>Specimens from the meteorite fall at 1:05 a. m., on 8 February 1969 at Pueblito de <span class="hlt">Allende</span>, Chihuahua, Mexico, have been recovered. The meteorite is a <span class="hlt">chondrite</span> (C3 and C4) with both opaque and microcrystalline matrices. Specimens were brought to a low background gamma counter less than 4 (1/2) days after the fall, and gamma rays from short-lived isotopes have been observed.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007GeCoA..71.1605B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007GeCoA..71.1605B"><span id="translatedtitle">Organic matter and metamorphic history of CO <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bonal, Lydie; Bourot-Denise, Michèle; Quirico, Eric; Montagnac, Gilles; Lewin, Eric</p> <p>2007-03-01</p> <p>The metamorphic grades of a series of eight CO3 <span class="hlt">chondrites</span> (ALHA77307, Colony, Kainsaz, Felix, Lancé, Ornans, Warrenton and Isna) have been quantified. The method used was based on the structural grade of the organic matter trapped in the matrix, which is irreversibly transformed by thermal metamorphism. The maturation of the organic matter is independent with respect to the mineralogical context and aqueous alteration. This metamorphic tracer is thus valid whatever the chemical class of <span class="hlt">chondrites</span>. Moreover, it is sensitive to the peak metamorphic temperature. The structural grade of the organic matter was used along with other metamorphic tracers such as petrography of opaque minerals, Fa and Fs silicate composition in type I chondrules, presolar grains and noble gas (P3 component) abundance. The deduced metamorphic hierarchy and the attributed petrographic types are the following: ALHA77307 (3.03) < Colony (3.1) < Kainsaz (3.6) < Felix (3.6 (1)) < Ornans (3.6 (2)) < Lancé (3.6 (3)) < Warrenton (3.7 (1)) < Isna (3.7 (2)). For most metamorphosed objects, the peak metamorphic temperature can be estimated using a geothermometer calibrated with terrestrial metasediments [Beyssac O., Goffe B., Chopin C., and Rouzaud J. N. (2002) Raman spectrum of <span class="hlt">carbonaceous</span> material in metasediments: a new geothermometer. J. Metamorph. Geol., 20, 859-871]. A value of 330 °C was obtained for <span class="hlt">Allende</span> (CV <span class="hlt">chondrite</span>), Warrenton and Isna, consistent with temperatures estimated from Fe diffusion [Weinbruch S., Armstrong J., and Palme H. (1994). Constraints on the thermal history of the <span class="hlt">Allende</span> parent body as derive from olivine-spinel thermometry and Fe/Mg interdiffusion in olivine. Geochim. Cosmochim. Acta58(2), 1019-1030.], from the Ni content in sulfide-metal assemblages [Zanda B., Bourot-Denise M., and Hewins R. (1995) Condensate sulfide and its metamorphic transformations in primitive <span class="hlt">chondrites</span>. Meteorit. Planet. Sci.30, A605.] and from the d002 interlayer spacing in poorly</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004GeCoA..68.2167K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004GeCoA..68.2167K"><span id="translatedtitle">Ca,Al-rich inclusions, amoeboid olivine aggregates, and Al-rich chondrules from the unique <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> Acfer 094: I. mineralogy and petrology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krot, Alexander N.; Fagan, Timothy J.; Keil, Klaus; McKeegan, Kevin D.; Sahijpal, Sandeep; Hutcheon, Ian D.; Petaev, Mikhail I.; Yurimoto, Hisayoshi</p> <p>2004-05-01</p> <p>Based on their mineralogy and petrography, ˜200 refractory inclusions studied in the unique <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span>, Acfer 094, can be divided into corundum-rich (0.5%), hibonite-rich (1.1%), grossite-rich (8.5%), compact and fluffy Type A (spinel-melilite-rich, 50.3%), pyroxene-anorthite-rich (7.4%), and Type C (pyroxene-anorthite-rich with igneous textures, 1.6%) Ca,Al-rich inclusions (CAIs), pyroxene-hibonite spherules (0.5%), and amoeboid olivine aggregates (AOAs, 30.2%). Melilite in some CAIs is replaced by spinel and Al-diopside and/or by anorthite, whereas spinel-pyroxene assemblages in CAIs and AOAs appear to be replaced by anorthite. Forsterite grains in several AOAs are replaced by low-Ca pyroxene. None of the CAIs or AOAs show evidence for Fe-alkali metasomatic or aqueous alteration. The mineralogy, textures, and bulk chemistry of most Acfer 094 refractory inclusions are consistent with their origin by gas-solid condensation and may reflect continuous interaction with SiO and Mg of the cooling nebula gas. It appears that only a few CAIs experienced subsequent melting. The Al-rich chondrules (ARCs; >10 wt% bulk Al 2O 3) consist of forsteritic olivine and low-Ca pyroxene phenocrysts, pigeonite, augite, anorthitic plagioclase, ± spinel, FeNi-metal, and crystalline mesostasis composed of plagioclase, augite and a silica phase. Most ARCs are spherical and mineralogically uniform, but some are irregular in shape and heterogeneous in mineralogy, with distinct ferromagnesian and aluminous domains. The ferromagnesian domains tend to form chondrule mantles, and are dominated by low-Ca pyroxene and forsteritic olivine, anorthitic mesostasis, and Fe,Ni-metal nodules. The aluminous domains are dominated by anorthite, high-Ca pyroxene and spinel, occasionally with inclusions of perovskite; have no or little FeNi-metal; and tend to form cores of the heterogeneous chondrules. The cores are enriched in bulk Ca and Al, and apparently formed from melting of CAI</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19820038768&hterms=stem&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dstem','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820038768&hterms=stem&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dstem"><span id="translatedtitle">XPS and STEM studies of <span class="hlt">Allende</span> acid insoluble residues</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Housley, R. M.; Clarke, D. R.</p> <p>1980-01-01</p> <p>Data on <span class="hlt">Allende</span> acid residues obtained both before and after etching with hot HNO3 are presented. X-ray photoelectron spectra show predominantly <span class="hlt">carbonaceous</span> material plus Fe-deficient chromite in both cases. The HNO3 oxidizes the <span class="hlt">carbonaceous</span> material to some extent. The small chromites in these residues have a wide range of compositions somewhat paralleling those observed in larger <span class="hlt">Allende</span> chromites and in Murchison chromites, especially in the high Al contents; however, they are deficient in divalent cations, which makes them metastable and indicates that they must have formed at relatively low temperatures. It is suggested that they formed by precipitation of Cr(3+) and Fe(3+) from olivine at low temperature or during rapid cooling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20010045186&hterms=rim&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Drim','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20010045186&hterms=rim&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Drim"><span id="translatedtitle">Petrographic Studies of Fine-grained Rims in the Yamato 791198 cm <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrite</span> and Comparison to Murchison and ALH81002</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chizmadia, L. J.; Brearley, A. J.</p> <p>2001-01-01</p> <p>Fine-grained rims in Y791198 (CM2) have been studied in detail using SEM and EPMA techniques. In comparison with the more highly altered CM <span class="hlt">chondrite</span>, ALH 81002, the rims are texturally and compositionally more heterogeneous. Additional information is contained in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013hsa7.conf..727T&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013hsa7.conf..727T&link_type=ABSTRACT"><span id="translatedtitle">Reflectance spectra of primitive <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Trigo-Rodríguez, J. M.; Moyano-Cambero, C. E.; Llorca, J.</p> <p>2013-05-01</p> <p>We are studying a wide sample of pristine <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> from the NASA Antarctic collection in order to get clues on the physico-chemical processes occurred in the parent bodies of these meteorites. We are obtaining laboratory reflectance spectra of different groups of <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>, but here we focus in CM and CI <span class="hlt">chondrites</span>. We discuss the main spectral features that can be used to identify primitive <span class="hlt">carbonaceous</span> asteroids by remote sensing techniques. Two different spectrometers were used covering the entire 0.3 to 30 μm electromagnetic window. Only a handful of Near Earth Objects (NEOs) exhibit bands or features clearly associated with aqueous alteration. Among them are the target asteroids of Osiris Rex and Marco Polo-R missions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015DPS....4721320C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015DPS....4721320C"><span id="translatedtitle">Scale-Dependent Measurements of Meteorite Strength and Fragmentation: Tamdakht (H5) and <span class="hlt">Allende</span> (CV3)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cotto-Figueroa, Desireé; Asphaug, Erik; Garvie, Laurence; Morris, Melissa; Rai, Ashwin; Chattopadhyay, Aditi; Chawla, Nikhilesh</p> <p>2015-11-01</p> <p>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 <span class="hlt">chondrite</span> that exhibits a heterogeneous structure criss-crossed with shock veins and centimeter-sized regions of white and light grey, and the <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> <span class="hlt">Allende</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMNH11A1889C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMNH11A1889C"><span id="translatedtitle">Scale-Dependent Measurements of Meteorite Strength and Fragmentation: Tamdakht (H5) and <span class="hlt">Allende</span> (CV3).</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cotto-Figueroa, D.; Asphaug, E. I.; Garvie, L. A. J.; Morris, M. A.; Rai, A.; Chattopadhyay, A.; Johnston, J.; Borkowski, L.</p> <p>2015-12-01</p> <p>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 <span class="hlt">chondrite</span> that exhibits a heterogeneous structure criss-crossed with shock veins and centimeter-sized regions of white and light grey, and the <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> <span class="hlt">Allende</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040065960&hterms=history+Science&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dhistory%2BScience','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040065960&hterms=history+Science&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dhistory%2BScience"><span id="translatedtitle">Lunar and Planetary Science XXXV: Concerning <span class="hlt">Chondrites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p>The Lunar and Planetary Science XXXV session entitled "Concerning <span class="hlt">Chondrites</span>" includes the following topics: 1) Petrology and Raman Spectroscopy of Shocked Phases in the Gujba CB <span class="hlt">Chondrite</span> and the Shock History of the CB Parent Body; 2) The Relationship Between CK and CV <span class="hlt">Chondrites</span>: A Single Parent Body Source? 3) Samples of Asteroid Surface Ponded Deposits in <span class="hlt">Chondritic</span> Meteorites; 4) Composition and Origin of SiO2-rich Objects in <span class="hlt">Carbonaceous</span> and Ordinary <span class="hlt">Chondrites</span>; 5) Re-Os Systematics and HSE distribution in Tieschitz (H3.6); Two Isochrons for One Meteorite; 6) Loss of Chromium from Olivine During the Metamorphism of <span class="hlt">Chondrites</span>; 7) Very Short Delivery Times of Meteorites After the L-<span class="hlt">Chondrite</span> Parent Body Break-Up 480 Myr Ago; and 8) The Complex Exposure History of a Very Large L/LL5 <span class="hlt">Chondrite</span> Shower: Queen Alexandra Range 90201.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014M%26PS...49.2064B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014M%26PS...49.2064B"><span id="translatedtitle">The secondary history of Sutter's Mill CM <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> based on water abundance and the structure of its organic matter from two clasts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beck, P.; Quirico, E.; Garenne, A.; Yin, Q.-Z.; Bonal, L.; Schmitt, B.; Montes-Hernandez, G.; Montagnac, G.; Chiriac, R.; Toche, F.</p> <p>2014-11-01</p> <p>Sutter's Mill is a regolith breccia composed of both heavily altered clasts and more reduced xenoliths. Here, we present a detailed investigation of fragments of SM18 and SM51. We have characterized the water content and the mineralogy by infrared (IR) and thermogravimetric analysis (TGA) and the structure of the organic compounds by Raman spectroscopy, to characterize the secondary history of the clasts, including aqueous alteration and thermal metamorphism. The three methods used in this study suggest that SM18 was significantly heated. The amount of water contained in phyllosilicates derived by TGA is estimated to be approximately 3.2 wt%. This value is quite low compared with other CM <span class="hlt">chondrites</span> that typically range from 6 to 12 wt%. The infrared transmission spectra of SM18 show that the mineralogy of the sample is dominated by a mixture of phyllosilicate and olivine. SM18 shows an intense peak at 11.2 μm indicative of olivine (Fig. 1). If we compare SM18 with other CM and metamorphosed CM <span class="hlt">chondrites</span>, it shows one of the most intense olivine signatures, and therefore a lower proportion of phyllosilicate minerals. The Raman results tend to support a short-duration heating hypothesis. In the ID/IG versus FWHM-D diagram, SM18 appears to be unusual compared to most CM samples, and close to the metamorphosed CM <span class="hlt">chondrites</span> Pecora Escarpment (PCA) 91008 and PCA 02012. In the case of SM51, infrared spectroscopy reveals that olivine is less abundant than in SM18 and the 10 μm silicate feature is more similar to that of moderately altered CM <span class="hlt">chondrites</span> (like Murchison or Queen Alexandra Range [QUE] 97990). Raman spectroscopy does not clearly point to a heating event for SM51 in the ID/IG versus FWHM-D diagram. However, TGA analysis suggests that SM51 was slightly dehydrated as the amount of water contained in phyllosilicates is approximately 3.7 wt%, which is higher than SM18, but still lower than phyllosilicate water contents in weakly altered CM <span class="hlt">chondrites</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005LPI....36.2381C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005LPI....36.2381C"><span id="translatedtitle">Keto-Acids in <span class="hlt">Carbonaceous</span> Meteorites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cooper, G.; Dugas, A.; Byrd, A.; Chang, P. M.; Washington, N.</p> <p>2005-03-01</p> <p>Keto-acids (pyruvic acid homologs) have been identified in <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> by GC-MS. All compounds were identified as their trimethylsilyl (TMS), isopropyl ester (ISP), and tert-butyldimethylsilyl (tBDMS) derivatives.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007GeCoA..71.1583B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007GeCoA..71.1583B"><span id="translatedtitle">Pb Pb dating constraints on the accretion and cooling history of <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bouvier, Audrey; Blichert-Toft, Janne; Moynier, Frédéric; Vervoort, Jeffrey D.; Albarède, Francis</p> <p>2007-03-01</p> <p>We have analyzed the Pb isotopic compositions of whole-rocks and various components (CAIs, chondrules, and/or mineral separates) of two <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>, <span class="hlt">Allende</span> (CV3) and Murchison (CM2), and nine ordinary <span class="hlt">chondrites</span>, Sainte Marguerite (H4), Nadiabondi and Forest City (H5), Kernouvé (H6), Bjurböle (L/LL4), Elenovka and Ausson (L5), Tuxtuac (LL5), and Saint-Séverin (LL6) by MC-ICP-MS. Three CAI fractions from <span class="hlt">Allende</span> define an isochron with an age of 4568.1 ± 9.4 Ma (MSWD = 0.08) and plot on the same isochron as fragments of the Efremovka inclusion E60 analyzed by Amelin et al. [Amelin, Y., Krot, A. N., Hutcheon, I. D., and Ulyanov, A. A. (2002a). Lead isotopic ages of chondrules and calcium-aluminum-rich inclusions. Science297, 1679-1683]. When these two groups of samples are combined, the isochron yields an age of 4568.5 ± 0.5 (MSWD = 0.90), which is our best estimate of the age of the Solar System. Chondrules and pyroxene-olivine fractions from the ordinary <span class="hlt">chondrites</span> yield ages that reflect the blocking of Pb isotope equilibration with the nebular gas. The combination of these ages with the corresponding metamorphic phosphate ages provides constraints on the thermal history of the different <span class="hlt">chondrite</span> parent bodies. Among the H <span class="hlt">chondrites</span>, Sainte Marguerite cooled to below ˜1100 K within a few My at 4565 Ma and to ˜800 K at 4563 Ma. Nadiabondi appears to have experienced a slightly more protracted cooling history with the corresponding interval lasting from 4559 to 4556 Ma. The data from Forest City and Kernouvé show evidence of late-stage perturbation with resulting U/Pb fractionation. Likewise, Pb isotopes in Tuxtuac (LL5) record a cooling history lasting from ˜4555 to 4544 Ma, which may indicate that the cooling history for the LL parent body was more prolonged than for the H parent body. We suggest a thermal evolution model for the growth of the planetary bodies based on the release of radiogenic heat from 26Al and 60Fe. This model</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750006596','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750006596"><span id="translatedtitle">The Magnetization of <span class="hlt">Carbonaceous</span> Meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Herndon, James Herndon</p> <p>1974-01-01</p> <p>Alternating field demagnetization experiments have been conducted on representative samples of the <span class="hlt">carbonaceous</span> meteorites (<span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> and ureilites). The results indicate that many, if not all, of these meteorites possess an intense and stable magnetic moment of extraterrestrial origin. Thermomagnetic analyses have been conducted on samples of all known <span class="hlt">carbonaceous</span> meteorites. In addition to yielding quantitative magnetite estimates, these studies indicate the presence of a thermally unstable component, troilite, which reacts with gaseous oxygen to form magnetite. It is proposed that the magnetite found in some <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> resulted from the oxidation of troilite during the early history of the solar system. The formation of pyrrhotite is expected as a natural consequence of magnetite formation via this reaction. Consideration is given to the implications of magnetite formation on paleointensity studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014mcp..book...65S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014mcp..book...65S"><span id="translatedtitle"><span class="hlt">Chondrites</span> and Their Components</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scott, E. R. D.; Krot, A. N.</p> <p></p> <p><span class="hlt">Chondrites</span> are extraordinary mixtures of materials with diverse origins that formed around other stars, in the solar nebula, and in their parent asteroids. Most <span class="hlt">chondrites</span> were so severely altered by aqueous fluids, thermal metamorphism, and impacts that the original characteristics of their components have been largely erased. But a few pristine <span class="hlt">chondrites</span> have preserved an exquisite mineralogical, chemical, isotopic, and chronological record of the first few million years of solar system history. The properties of diverse types of <span class="hlt">carbonaceous</span>, ordinary, and enstatite <span class="hlt">chondrites</span> focusing on the most pristine samples are reviewed to establish the chemical, isotopic, and mineralogical properties and origins of their components and to elucidate the asteroidal processes that modified them. Refractory inclusions - amoeboid olivine aggregates and Ca-Al-rich inclusions - were the first solids to form in the solar nebula near to the protosun. Chondrules and associated metallic Fe-Ni grains were still forming several million years later when the earliest planetesimals, which melted due to heat from 26Al decay, were colliding. In the least-altered <span class="hlt">chondrites</span>, matrix material, which coats chondrules and other components, is largely composed of micrometer-sized silicates and amorphous materials, which formed at high temperatures, plus small amounts (up to 200 ppm) of presolar oxides and silicates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940016170&hterms=Igneous+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D%2528Igneous%2Brocks%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940016170&hterms=Igneous+rocks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3D%2528Igneous%2Brocks%2529"><span id="translatedtitle">Igneous rock from Severnyi Kolchim (H3) <span class="hlt">chondrite</span>: Nebular origin</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nazarov, M. A.; Brandstaetter, F.; Kurat, G.</p> <p>1993-01-01</p> <p>The discovery of lithic fragments with compositions and textures similar to igneous differentiates in unequilibrated ordinary <span class="hlt">chondrites</span> (UOC's) and <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> (CC's) has been interpreted as to suggest that planetary bodies existed before <span class="hlt">chondrites</span> were formed. As a consequence, <span class="hlt">chondrites</span> (except, perhaps CI <span class="hlt">chondrites</span>) cannot be considered primitive assemblages of unprocessed nebular matter. We report about our study of an igneous clast from the Severnyi Kolchim (H3) <span class="hlt">chondrite</span>. The results of the study are incompatible with an igneous origin of the clast but are in favor of a nebular origin similar to that of chondrules.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19840043835&hterms=acid+hydrofluoric&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dacid%2Bhydrofluoric','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19840043835&hterms=acid+hydrofluoric&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dacid%2Bhydrofluoric"><span id="translatedtitle">Colloidally separated samples from <span class="hlt">Allende</span> residues - Noble gases, carbon and an ESCA-study</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ott, U.; Kronenbitter, J.; Flores, J.; Chang, S.</p> <p>1984-01-01</p> <p>Results are presented which strengthen the hypothesis of heterogeneity among the carbon- and nitrogen-bearing phases of the <span class="hlt">Allende</span> meteorite. These data also highlight the possibility of performing physical separations yielding samples in which some of the noble gas- and carbon-bearing phases are extraordinarily predominant over others. The conclusion, based on mass and isotope balance arguments, that a significant portion of the <span class="hlt">carbonaceous</span> matter in <span class="hlt">Allende</span> is likely to be gas-poor or gas-free need not weaken the case for <span class="hlt">carbonaceous</span> carriers for the major noble gas components. The concept that acid-soluble <span class="hlt">carbonaceous</span> phases contain a multiplicity of components, each of which may have formed under a multiplicity of different physical-chemical conditions, is reemphasized by the results of the present study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995Metic..30..494C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995Metic..30..494C&link_type=ABSTRACT"><span id="translatedtitle">The 'Porky' Inclusion from the Axtell <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrite</span>: A Hercynite-bearing Condensate with Large 48Ca and 50Ti Excesses</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Caillet, C.; Zinner, E.</p> <p>1995-09-01</p> <p> at varying temperatures (highest for the core, lowest for the fine-grained regions) and under varying redox conditions and trace element compositions. The refractory trace elements measured in hercynite are likely to reside in ilmenite (the abundances in this phase would then be ~15 times higher than shown in Fig. 1 for hercynite). In contrast to large 48Ca and 50Ti depletions in hibonite-hercynite inclusion Lanc HH-1 [2], Porky shows extreme excesses in 48Ca (37.3+/-5.9 (2s) per mil in hibonite and 27.4+/-4.8 per mil in diopside) and 50Ti (~62 per mil in hibonite and ilmenite). No clear 26Mg excess and no Mg and Fe isotopic mass fractionation were detected. Fe isotopic ratios in hercynite are normal; the <span class="hlt">Allende</span> inclusion EK1-4-1 thus remains the only object in which a large 58Fe excess is associated with 48Ca and 50Ti excesses [4]. References: [1] Brigham C. A. et al. (1986) LPSC XVII, 85-86. [2] Fahey A. J. et al. (1994) GCA, 58, 4779-4793. [3] Caillet C. (1994) Meteoritics, 29, 453-454. [4] V"lkening J. and Papanastassiou D. A. (1989) Astrophys. J., 347, L43-L46.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeCoA.130...78Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeCoA.130...78Z"><span id="translatedtitle">Origins of Al-rich chondrules: Clues from a compound Al-rich chondrule in the Dar al Gani 978 <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Ai-Cheng; Itoh, Shoichi; Sakamoto, Naoya; Wang, Ru-Cheng; Yurimoto, Hisayoshi</p> <p>2014-04-01</p> <p>Aluminum-rich chondrules are one of the most interesting components of primitive <span class="hlt">chondrites</span>, because they have characteristics that are similar to both Ca, Al-rich inclusions (CAIs) and ferromagnesian chondrules. However, their precursor and formation history remain poorly constrained, especially with respect to their oxygen isotopic distributions. In this study, we report on the petrography, mineralogy, oxygen isotope ratios, and rare-earth-element compositions of a sapphirine-bearing Al-rich chondrule (SARC) in the ungrouped <span class="hlt">chondrite</span> Dar al Gani (DaG) 978. The SARC has a complex core-mantle-rim texture; while both the core and the mantle are mainly composed of Al-rich enstatite and anorthite with minor amounts of mesostasis, these regions are distinguished by the presence of Fe-rich spinel and sapphirine in the core and their absence in the mantle. The rim of the SARC consists mainly of Fe-rich olivine, enstatite, and Fe-Ni metal. Spinel and some olivine grains in the SARC are 16O-rich, with Δ17O values down to -20‰ and -23‰, respectively. Enstatite, sapphirine, and most olivine grains have similar Δ17O values (∼ -7‰), which are lower than those of anorthite and the mesostasis (including augite therein) (Δ17O: ∼ -3‰). Mesostasis from both the core and mantle have Group II rare-earth-element (REE) patterns; however, the core mesostasis has higher REE concentrations than the mantle mesostasis. These observations provide a strong indication that the SARC formed by the melting and crystallization of a mixture of materials from Group II CAIs and ferromagnesian chondrules. Both spinel and olivine with 16O-rich features could be of relict origin. The 16O-poor isotopic compositions of most components in Al-rich chondrules can be explained by oxygen isotopic exchange between the melt and 16O-poor nebular gas (Δ17O: ∼ -7‰) during melting in chondrule-forming regions; whereas the anorthite and mesostasis could have experienced further oxygen isotopic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19880037988&hterms=Heymann&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DHeymann','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19880037988&hterms=Heymann&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DHeymann"><span id="translatedtitle">Gas release and ordering of carbon in the <span class="hlt">Allende</span> meteorite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Heymann, D.; Read, N.</p> <p>1987-01-01</p> <p>An attempt is made to ascertain whether the inert gas atoms leave their carrier phases by volume diffusion, with intact internal phase frameworks, or are instead expelled from the solids as a results of substantial rearrangement, during release from samples of the <span class="hlt">Allende</span> <span class="hlt">carbonaceous</span> meteorite. Gas release over the 300-1100 C range was followed by Raman spectroscopic studies in the 1360 and 1580/cm wavelength bands of carbon. The results obtained indicate that the gas release at high temperatures is causally related to the ordering of carbon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5389287','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5389287"><span id="translatedtitle">Discovery of s-process Nd in <span class="hlt">Allende</span> residue</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Clayton, D.D.</p> <p>1983-08-15</p> <p>New interpretation is given to the isotopic anomalie detected by Lugmair et al. in an acid-resistant residue of the <span class="hlt">Allende</span> meteorite. If the the /sup 142/Nd excess is due to /sup 146/Sm decay, as the discoverers proposed, I argue that the decay has occurred in interstellar grains, so that the concludion that /sup 146/Sm(1.03 x 10/sup 8/ yr) was alive in the solar system is premature. I show by renormalizing their data that the discovery is likely to be s-process Nd, confirming the survival of red-giang stardust in <span class="hlt">carbonaceous</span> interstellar dust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1008888','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1008888"><span id="translatedtitle">Unambiguous voids in <span class="hlt">Allende</span> chondrules and refractory inclusions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Murray, J.; Boesenberg, J.S.; Ebel, D.S.</p> <p>2003-03-26</p> <p>Void space can be caused by thin section preparation. 3-dimensional tomographic analysis, prior to sectioning, shows that several very different types of voids are abundant in <span class="hlt">Allende</span> meteorite inclusions. Formation models are proposed for each type. Void spaces in the components of <span class="hlt">chondritic</span> meteorites have received little attention, perhaps due to ambiguities attendant upon their very existence, and also their origin. Computer-aided microtomography allows the 3-dimensional imaging and analysis of void spaces within solid objects. Several striking examples of void spaces, apparently enclosed by solid material, resulted from our observations of large chondrules and CAIs from the <span class="hlt">Allende</span> (CV3) meteorite. These voids are 'unambiguous' because their existence cannot be ascribed to plucking during sample preparation, as would be the case in traditional 2-dimensional thin section petrography. Although we focus on large objects in <span class="hlt">Allende</span>, preliminary observations indicate that void spaces are prevalent in chondrules and refractory inclusions in many meteorites. Voids remain ambiguous, however, because their structure and appearance vary between chondrules and CAIs, suggesting there may be different causes of void formation in particular objects. Some voids appear to have formed as a result of dilation during cooling. Others are evidence of hydrothermal leaching on the parent body followed by partial chemical replacement. Alternatively, vapor-mediated leaching and replacement may have occurred in the nebula. Yet another possibility is internal brecciation caused by impact, while the object was still free floating in the nebula, and perhaps still partially molten.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70011105','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70011105"><span id="translatedtitle">U-Th-Pb and Rb-Sr systematics of <span class="hlt">Allende</span> and U-Th-Pb systematics of Orgueil</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Tatsumoto, M.; Unruh, D.M.; Desborough, G.A.</p> <p>1976-01-01</p> <p> chondrules which contain less radiogenic lead did, however, not fit on the chord. The Rb-Sr data of <span class="hlt">Allende</span> did not define an isochron suggesting that the Rb-Sr system was also disturbed by a later event, as suggested by the U-Pb concordia data. The lowest observed 87Sr/86Sr ratio in <span class="hlt">Allende</span> inclusions is similar to the initial ratio of the Angra dos Reis achondrite (Papanastassiou, Thesis, 1970). The initial Pb isotopic composition of Orgueil calculated by a single-stage evolution model is more radiogenic than that of Canyon Diablo troilite. To reconcile the U-Pb data of Orgueil and <span class="hlt">Allende</span>, we propose that the initial lead isotopic composition of the <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> was slightly different from that of Canyon Diablo troilite Pb. ?? 1976.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19780063755&hterms=rare+earth+elements&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Drare%2Bearth%2Belements','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19780063755&hterms=rare+earth+elements&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Drare%2Bearth%2Belements"><span id="translatedtitle">Rare-earth abundances in <span class="hlt">chondritic</span> meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Evensen, N. M.; Hamilton, P. J.; Onions, R. K.</p> <p>1978-01-01</p> <p>Fifteen <span class="hlt">chondrites</span>, including eight <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>, were analyzed for rare earth element abundances by isotope dilution. Examination of REE for a large number of individual <span class="hlt">chondrites</span> shows that only a small proportion of the analyses have flat unfractionated REE patterns within experimental error. While some of the remaining analyses are consistent with magmatic fractionation, many patterns, in particular those with positive Ce anomalies, can not be explained by known magmatic processes. Elemental abundance anomalies are found in all major <span class="hlt">chondrite</span> classes. The persistence of anomalies in <span class="hlt">chondritic</span> materials relatively removed from direct condensational processes implies that anomalous components are resistant to equilibrium or were introduced at a late stage of <span class="hlt">chondrite</span> formation. Large-scale segregation of gas and condensate is implied, and bulk variations in REE abundances between planetary bodies is possible.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997P%26SS...45..653M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997P%26SS...45..653M"><span id="translatedtitle">Biological potential of extraterrestrial materials - 1. Nutrients in <span class="hlt">carbonaceous</span> meteorites, and effects on biological growth</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mautner, Michael N.</p> <p>1997-06-01</p> <p>Soil nutrient analysis of the Murchison C2 <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> shows biologically available S, P, Ca, Mg, Na, K and Fe and cation exchange capacity (CEC) at levels comparable with terrestrial agricultural soils. Weathering, and aqueous, hydrothermal (121°C, 15 min) and high-temperature (550°C, 3 h) processing increase the extractable nutrients. Extractable phosphorus (by 0.3 M NH 4F + 0.1 M HCl) content, which may be growth-limiting, is 6.3 μg g -1 in the unprocessed meteorite, but increases to 81 μg g -1 by hydrothermal processing and weathering, and to 130 μg g -1 by high temperature processing. The cation exchange capacity (CEC), attributed mainly to the organic fraction, corresponds responds to 345 meq per 100 g of the polymer, suggesting one ionizable COOH or OH group per 3-4 aromatic rings. The <span class="hlt">Allende</span> C3(V) meteorite has low extractable Ca, Mg and K, in parallel to its low organic content and CEC, but high extractable P levels (160 μg g -1). Biological effects are observed on growth of the soil microorganisms Flavobacterium oryzihabitans and Nocardia asteroides in meteorite extracts, and the population levels suggest that P is the limiting nutrient. Effects on plant growth are examined on Solanum tuberosum (potato), where extracts of the Murchison meteorite lead to enhanced growth and pigmentation. The biologically available organic and inorganic nutrients in <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> can provide concentrated solutions for prebiotic and early life processes, and serve as soils and fertilizers for future space-based biological expansion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70012226','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70012226"><span id="translatedtitle">Sr isotopic fractionation in Ca-Al inclusions from the <span class="hlt">Allende</span> meteorite</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Patchett, P.J.</p> <p>1980-01-01</p> <p>True relative Sr isotopic compositions, determined by double spiking on Ca-Al inclusions from the <span class="hlt">Allende</span> meteorite show up to 1.5??? per mass unit mass fractionation relative to the Earth and bulk <span class="hlt">chondrites</span>. All abnormal inclusions are light-isotope enriched. A lack of isotopically heavy Sr in inclusions would place constraints on the time, place and mechanism of origin of these objects. ?? 1980 Nature Publishing Group.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120011762','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120011762"><span id="translatedtitle">Mineralogy and Oxygen Isotope Compositions of an Unusual Hibonite-Perovskite Refractory Inclusion from <span class="hlt">Allende</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Keller, L. P.; Snead, C.; Rahman, Z.; McKeegan, K. D.</p> <p>2012-01-01</p> <p>Hibonite-rich Ca- and Al-rich inclusions (CAIs) are among the earliest formed solids that condensed in the early nebula. We discovered an unusual refractory inclusion from the <span class="hlt">Allende</span> CV3 <span class="hlt">chondrite</span> (SHAL) containing an approx 500 micron long single crystal of hibonite and co-existing coarse-grained perovskite. The mineralogy and petrography of SHAL show strong similarities to some FUN inclusions, especially HAL. Here we report on the mineralogy, petrography, mineral chemistry and oxygen isotopic compositions in SHAL.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015E%26PSL.422...18K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015E%26PSL.422...18K"><span id="translatedtitle">Chemical characteristic of R <span class="hlt">chondrites</span> in the light of P, REEs, Th and U abundances</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khan, Rahat; Shirai, Naoki; Ebihara, Mitsuru</p> <p>2015-07-01</p> <p>Rare earth elements (REEs), Th, U and P were determined in 15 Rumuruti (R)-type <span class="hlt">chondrites</span> and the <span class="hlt">Allende</span> CV <span class="hlt">chondrite</span>. Repeated analyses of <span class="hlt">Allende</span> for REEs, Th and U by ICP-MS and P by ICP-AES, and comparisons of these data with literature values ensure high reproducibility (precision) and reliability (accuracy) of acquired data. CI-normalized REE abundances in R <span class="hlt">chondrites</span> are slightly enriched in heavy REEs with a small, positive Ce anomaly, in contrast to <span class="hlt">Allende</span>. CI-normalized Pr/Tm and Nd/Yb ratios show a positive correlation, suggesting the heterogeneous mixing of two components (CI-like and refractory-rich materials) during the accretion of the R <span class="hlt">chondrite</span> parent body. A Ce anomaly, however, was likely homogeneously present in the nebula. A mean Th/U ratio of R <span class="hlt">chondrites</span> is 3.81 ± 0.13 (1 σ), which is 5.1% higher than the CI ratio. Probably, the Th-U fractionation was inherited from the nebula from which the R <span class="hlt">chondrite</span> parent body formed. Besides the Th-U fractionation, REEs and Th-U are heterogeneously fractionated in R <span class="hlt">chondrites</span>, for which parent body processing is assumed to be the cause. A mean P content of R <span class="hlt">chondrites</span> (1254 μg/g) is higher than for any ordinary <span class="hlt">chondrite</span> and is close to the EL mean. There appears to be a negative correlation between P and REEs contents in R <span class="hlt">chondrites</span>. It is probable that REEs were diluted by extraneously supplied, REEs-depleted and P-containing materials (schreibersite or metal). This process must have occurred heterogeneously during accretion so that the heterogeneity of P-containing materials was preserved in the R <span class="hlt">chondrite</span> parent body and individual R <span class="hlt">chondrites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160007503','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160007503"><span id="translatedtitle">C <span class="hlt">Chondrite</span> Clasts in H <span class="hlt">Chondrite</span> Regolith Breccias: Something Different</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zolensky, M. E.; Fries, M.; Utas, J.; Chan, Q. H.-S.; Kebukawa, Y.; Steele, A.; Bodnar, R. J.; Ito, M.; Nakashima, D.; Greenwood, R.; Rahman, Z.; Le, L.; Ross, D. K.</p> <p>2016-01-01</p> <p>Zag (H3-6) and Monahans (1998) (H5) are regolith breccias that contain 4.5 GY old halite crystals which in turn contain abundant inclusions of aqueous fluids, solids and organics [1-4]. We have previously proposed that these halites originated on a hydro-volcanically-active C-class asteroid, probably Ceres [3-7]. We have begun a detailed analysis of the included solids and organics and are re-examining the related <span class="hlt">carbonaceous</span> (C)) <span class="hlt">chondrite</span> clast we previously reported in Zag [5-7]. These new investigations will potentially reveal the mineralogy of asteroid Ceres. We report here on potentially identical C <span class="hlt">chondrite</span> clasts in the H <span class="hlt">chondrite</span> regolith breccias Tsukuba (H5-6) and Carancas (H4-5). The clast in Tsukuba was known before [8], but the Carancas clast is newly recognized.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010SPIE.7819E..13W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010SPIE.7819E..13W"><span id="translatedtitle">Bacterial morphologies in <span class="hlt">carbonaceous</span> meteorites and comet dust</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wickramasinghe, Chandra; Wallis, Max K.; Gibson, Carl H.; Wallis, Jamie; Al-Mufti, Shirwan; Miyake, Nori</p> <p>2010-09-01</p> <p>Three decades ago the first convincing evidence of microbial fossils in <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> was discovered and reported by Hans Dieter Pflug and his collaborators. In addition to morphology, other data, notably laser mass spectroscopy, confirmed the identification of such structures as putative bacterial fossils. Balloon-borne cryosampling of the stratosphere enables recovery of fragile cometary dust aggregates with their structure and <span class="hlt">carbonaceous</span> matter largely intact. SEM studies of texture and morphology of particles in the Cardiff collection, together with EDX identifications, show two main types of putative bio-fossils - firstly organic-walled hollow spheres around 10μm across, secondly siliceous diatom skeletons similar to those found in <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> and terrestrial sedimentary rocks and termed 'acritarchs'. Since <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> (particularly Type 1 <span class="hlt">chondrites</span>) are thought to be extinct comets the data reviewed in this article provide strong support for theories of cometary panspermia.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20010044934&hterms=osmium&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dosmium','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20010044934&hterms=osmium&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dosmium"><span id="translatedtitle">Osmium Isotopic Compositions of <span class="hlt">Chondrites</span> and Earth's Primitive Upper Mantle: Constraints on the Late Veneer</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Walker, R. J.; Horan, M. F.; Morgan, J. W.; Meisel, T.</p> <p>2001-01-01</p> <p>The 187 Os/188 Os of <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> averages approximately 2% lower than for enstatite and ordinary <span class="hlt">chondrites</span>. The primitive upper mantle ratio for the Earth best matches that of ordinary and enstatite <span class="hlt">chondrites</span>. Additional information is contained in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19820030291&hterms=acid+hydrofluoric&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dacid%2Bhydrofluoric','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820030291&hterms=acid+hydrofluoric&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dacid%2Bhydrofluoric"><span id="translatedtitle">Noble-gas-rich separates from the <span class="hlt">Allende</span> meteorite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ott, U.; Mack, R.; Chang, S.</p> <p>1981-01-01</p> <p>Predominantly <span class="hlt">carbonaceous</span> HF/HCl-resistant residues from the <span class="hlt">Allende</span> meteorite are studied. Samples are characterized by SEM/EDXA, X-ray diffraction, INAA, C, S, H, N, and noble gas analyses. Isotopic data for carbon show variations no greater than 5%, while isotopic data from noble gases confirm previously established systematics. Noble gas abundances correlate with those of C and N, and concomitant partial loss of C and normal trapped gas occur during treatments with oxidizing acids. HF/HCl demineralization of bulk meteorite results in similar fractional losses of C and trapped noble gases, which leads to the conclusion that various macromolecular <span class="hlt">carbonaceous</span> substances serve as the main host phase for normal trapped noble gases and anomalous gases in acid-resistant residues, and as the carrier of the major part of trapped noble gases lost during HF/HCl demineralization. Limits on the possible abundances of dense mineralic host phases in the residues are obtained, and considerations of the nucleogenetic origin for CCF-XE indicate that <span class="hlt">carbonaceous</span> host phases and various forms of organic matter in <span class="hlt">carbonaceous</span> meteorites may have a presolar origin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19810038484&hterms=uranium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Duranium','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19810038484&hterms=uranium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Duranium"><span id="translatedtitle">The isotopic composition of uranium and lead in <span class="hlt">Allende</span> inclusions and meteoritic phosphates</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chen, J. H.; Wasserburg, G. J.</p> <p>1981-01-01</p> <p>The isotopic compositions of uranium and lead in Ca-Al-rich inclusions from the <span class="hlt">Allende</span> <span class="hlt">chondrite</span> and in whitlockite from the St. Severin <span class="hlt">chondrite</span> and the Angra dos Reis achondrite are reported. Isoptopic analysis of acid soluble fractions of the <span class="hlt">Allende</span> inclusions and the meteoritic whitlockite, which show isotopic anomalies in other elements, reveals U-235/U-238 ratios from 1/137.6 to 1/138.3, within 20 per mil of normal terrestrial U abundances. The Pb isotopic compositions of five coarse-grained <span class="hlt">Allende</span> inclusions give a mean Pb-207/Pb-206 model age of 4.559 + or - 0.015 AE, in agreement with the U results. Pb isotope ratios of two fine-grained inclusions and a coarse-grained inclusion with strong mass fractionation and some nonlinear isotopic anomalies indicate that the U-Pb systems of these inclusions have evolved differently from the rest of <span class="hlt">Allende</span>. Th/U abundance ratios in the <span class="hlt">Allende</span> inclusions and meteoritic phosphate are found to range from 3.8 to 96, presumably indicating an optimal case for Cm/U fractionation, although the normal U concentrations do not support claims of abundant live Cm-247 or Cm-247/U-238 fractionation at the time of meteorite formation, in contrast to previous results. A limiting Cm-247/U-235 ratio of 0.004 at the time of meteorite formation is calculated which implies that the last major r process contribution at the protosolar nebula was approximately 100 million years prior to Al-26 formation and injection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860019424','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860019424"><span id="translatedtitle">Metastable carbon in two <span class="hlt">chondritic</span> porous interplanetary dust particles</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rietmeijer, F. J. M.; Mackinnon, I. D. R.</p> <p>1986-01-01</p> <p>An understanding of <span class="hlt">carbonaceous</span> matter in primitive extraterrestrial materials is an essential component of studies on dust evolution in the interstellar medium and the early history of the Solar System. Analytical Electron Microscopy (AEM) on <span class="hlt">carbonaceous</span> material in two <span class="hlt">Chondritic</span> Porous (CP) aggregrates is presented. The study suggests that a record of hydrocarbon carbonization may also be preserved in these materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/944372','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/944372"><span id="translatedtitle">OXYGEN ISOTOPIC COMPOSITIONS OF THE <span class="hlt">ALLENDE</span> TYPE C CAIs: EVIDENCE FOR ISOTOPIC EXCHANGE DURING NEBULAR MELTING AND ASTEROIDAL THERMAL METAMORPHISM</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Krot, A N; Chaussidon, M; Yurimoto, H; Sakamoto, N; Nagashima, K; Hutcheon, I D; MacPherson, G J</p> <p>2008-02-21</p> <p>Based on the mineralogy and petrography, coarse-grained, igneous, anorthite-rich (Type C) calcium-aluminum-rich inclusions (CAIs) in the CV3 <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> <span class="hlt">Allende</span> have been recently divided into three groups: (i) CAIs with melilite and Al,Ti-diopside of massive and lacy textures (coarse grains with numerous rounded inclusions of anorthite) in a fine-grained anorthite groundmass (6-1-72, 100, 160), (ii) CAI CG5 with massive melilite, Al,Ti-diopside and anorthite, and (iii) CAIs associated with chondrule material: either containing chondrule fragments in their peripheries (ABC, TS26) or surrounded by chondrule-like, igneous rims (93) (Krot et al., 2007a,b). Here, we report in situ oxygen isotopic measurements of primary (melilite, spinel, Al,Ti-diopside, anorthite) and secondary (grossular, monticellite, forsterite) minerals in these CAIs. Spinel ({Delta}{sup 17}O = -25{per_thousand} to -20{per_thousand}), massive and lacy Al,Ti-diopside ({Delta}{sup 17}O = -20{per_thousand} to -5{per_thousand}) and fine-grained anorthite ({Delta}{sup 17}O = -15{per_thousand} to -2{per_thousand}) in 100, 160 and 6-1-72 are {sup 16}O-enriched relative spinel and coarse-grained Al,Ti-diopside and anorthite in ABC, 93 and TS26 ({Delta}{sup 17}O ranges from -20{per_thousand} to -15{per_thousand}, from -15{per_thousand} to -5{per_thousand}, and from -5{per_thousand} to 0{per_thousand}, respectively). In 6-1-72, massive and lacy Al,Ti-diopside grains are {sup 16}O-depleted ({Delta}{sup 17}O {approx} -13{per_thousand}) relative to spinel ({Delta}{sup 17}O = -23{per_thousand}). Melilite is the most {sup 16}O-depleted mineral in all <span class="hlt">Allende</span> Type C CAIs. In CAI 100, melilite and secondary grossular, monticellite and forsterite (minerals replacing melilite) are similarly {sup 16}O-depleted, whereas grossular in CAI 160 is {sup 16}O-enriched ({Delta}{sup 17}O = -10{per_thousand} to -6{per_thousand}) relative to melilite ({Delta}{sup 17}O = -5{per_thousand} to -3{per_thousand}). We infer</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160005068','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160005068"><span id="translatedtitle">A <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrite</span> Based Simulant of Phobos</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rickman, Douglas L.; Patel, Manish; Pearson, V.; Wilson, S.; Edmunson, J.</p> <p>2016-01-01</p> <p>In support of an ESA-funded concept study considering a sample return mission, a simulant of the Martian moon Phobos was needed. There are no samples of the Phobos regolith, therefore none of the four characteristics normally used to design a simulant are explicitly known for Phobos. Because of this, specifications for a Phobos simulant were based on spectroscopy, other remote measurements, and judgment. A composition based on the Tagish Lake meteorite was assumed. The requirement that sterility be achieved, especially given the required organic content, was unusual and problematic. The final design mixed JSC-1A, antigorite, pseudo-agglutinates and gilsonite. Sterility was achieved by radiation in a commercial facility.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70031384','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70031384"><span id="translatedtitle">Investigation of magnesium isotope fractionation during basalt differentiation: Implications for a <span class="hlt">chondritic</span> composition of the terrestrial mantle</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Teng, F.-Z.; Wadhwa, M.; Helz, R.T.</p> <p>2007-01-01</p> <p>To investigate whether magnesium isotopes are fractionated during basalt differentiation, we have performed high-precision Mg isotopic analyses by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) on a set of well-characterized samples from Kilauea Iki lava lake, Hawaii, USA. Samples from the Kilauea Iki lava lake, produced by closed-system crystal-melt fractionation, range from olivine-rich cumulates to highly differentiated basalts with MgO content ranging from 2.37 to 26.87??wt.%. Our results demonstrate that although these basalts have diverse chemical compositions, mineralogies, crystallization temperatures and degrees of differentiation, their Mg isotopic compositions display no measurable variation within the limits of our external precision (average ??26Mg = - 0.36 ?? 0.10 and ??25Mg = - 0.20 ?? 0.07; uncertainties are 2SD). This indicates that Mg isotopic fractionation during crystal-melt fractionation at temperatures of ??? 1055????C is undetectable at the level of precision of the current investigation. Calculations based on our data suggest that at near-magmatic temperatures the maximum fractionation in the 26Mg/24Mg ratio between olivine and melt is 0.07???. Two additional oceanic basalts, two continental basalts (BCR-1 and BCR-2), and two primitive <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> (<span class="hlt">Allende</span> and Murchison) analyzed in this study have Mg isotopic compositions similar to the Kilauea Iki lava lake samples. In contrast to a recent report [U. Wiechert, A.N. Halliday, Non-<span class="hlt">chondritic</span> magnesium and the origins of the inner terrestrial planets, Earth and Planetary Science Letters 256 (2007) 360-371], the results presented here suggest that the Bulk Silicate Earth has a <span class="hlt">chondritic</span> Mg isotopic composition. ?? 2007.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140012796','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140012796"><span id="translatedtitle">Contrasting Size Distributions of Chondrules and Inclusions in <span class="hlt">Allende</span> CV3</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fisher, Kent R.; Tait, Alastair W.; Simon, Jusin I.; Cuzzi, Jeff N.</p> <p>2014-01-01</p> <p>There are several leading theories on the processes that led to the formation of <span class="hlt">chondrites</span>, e.g., sorting by mass, by X-winds, turbulent concentration, and by photophoresis. The juxtaposition of refractory inclusions (CAIs) and less refractory chondrules is central to these theories and there is much to be learned from their relative size distributions. There have been a number of studies into size distributions of particles in <span class="hlt">chondrites</span> but only on relatively small scales primarily for chondrules, and rarely for both Calcium Aluminum-rich Inclusions (CAIs) and chondrules in the same sample. We have implemented macro-scale (25 cm diameter sample) and high-resolution microscale sampling of the <span class="hlt">Allende</span> CV3 <span class="hlt">chondrite</span> to create a complete data set of size frequencies for CAIs and chondrules.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960041441','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960041441"><span id="translatedtitle">Chemical and physical studies of type 3 <span class="hlt">chondrites</span> 12: The metamorphic history of CV <span class="hlt">chondrites</span> and their components</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Guimon, R. Kyle; Symes, Steven J. K.; Sears, Derek W. G.</p> <p>1995-01-01</p> <p>The induced thermoluminescence (TL) properties of 16 CV and CV-related <span class="hlt">chondrites</span>, four CK <span class="hlt">chondrites</span> and Renazzo (CR2) have been measured in order to investigate their metamorphic history. The petrographic, mineralogical and bulk compositional differences among the CV <span class="hlt">chondrites</span> indicate that the TL sensitivity of the approximately 130 C TL peak is reflecting the abundance of ordered feldspar, especially in chondrule mesostasis, which in turn reflects parent-body metamorphism. The TL properties of 18 samples of homogenized <span class="hlt">Allende</span> powder heated at a variety of times and temperatures, and cathodoluminescence mosaics of Axtell and Coolidge, showed results consistent with this conclusion. Five refractory inclusions from <span class="hlt">Allende</span>, and separates from those inclusions, were also examined and yielded trends reflecting variations in mineralogy indicative of high peak temperatures (either metamorphic or igneous) and fairly rapid cooling. The CK <span class="hlt">chondrites</span> are unique among metamorphosed <span class="hlt">chondrites</span> in showing no detectable induced TL, which is consistent with literature data that suggests very unusual feldspar in these meteorites. Using TL sensitivity and several mineral systems and allowing for the differences in the oxidized and reduced subgroups, the CV and CV-related meteorites can be divided into petrologic types analogous to those of the ordinary and CO type 3 <span class="hlt">chondrites</span>. Axtell, Kaba, Leoville, Bali, Arch and ALHA81003 are type 3.0-3.1, while ALH84018, Efremovka, Grosnaja, <span class="hlt">Allende</span> and Vigarano are type 3.2-3.3 and Coolidge and Loongana 001 are type 3.8. Mokoia is probably a breccia with regions ranging in petrologic type from 3.0 to 3.2. Renazzo often plots at the end of the reduced and oxidized CV <span class="hlt">chondrite</span> trends, even when those trends diverge, suggesting that in many respects it resembles the unmetamorphosed precursors of the CV <span class="hlt">chondrites</span>. The low-petrographic types and low-TL peak temperatures of all samples, including the CV3.8 <span class="hlt">chondrites</span>, indicates metamorphism</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70016061','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70016061"><span id="translatedtitle">Actinide abundances in ordinary <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hagee, B.; Bernatowicz, T.J.; Podosek, F.A.; Johnson, M.L.; Burnett, D.S.; Tatsumoto, M.</p> <p>1990-01-01</p> <p>Measurements of 244Pu fission Xe, U, Th, and light REE (LREE) abundances, along with modal petrographic determinations of phosphate abundances, were carried out on equilibrated ordinary <span class="hlt">chondrites</span> in order to define better the solar system Pu abundance and to determine the degree of variation of actinide and LREE abundances. Our data permit comparison of the directly measured Pu/ U ratio with that determined indirectly as (Pu/Nd) ?? (Nd/U) assuming that Pu behaves chemically as a LREE. Except for Guaren??a, and perhaps H <span class="hlt">chondrites</span> in general, Pu concentrations are similar to that determined previously for St. Se??verin, although less precise because of higher trapped Xe contents. Trapped 130Xe 136Xe ratios appear to vary from meteorite to meteorite, but, relative to AVCC, all are similar in the sense of having less of the interstellar heavy Xe found in <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> acid residues. The Pu/U and Pu/Nd ratios are consistent with previous data for St. Se??verin, but both tend to be slightly higher than those inferred from previous data on Angra dos Reis. Although significant variations exist, the distribution of our Th/U ratios, along with other precise isotope dilution data for ordinary <span class="hlt">chondrites</span>, is rather symmetric about the CI <span class="hlt">chondrite</span> value; however, actinide/(LREE) ratios are systematically lower than the CI value. Variations in actinide or LREE absolute and relative abundances are interpreted as reflecting differences in the proportions and/or compositions of more primitive components (chondrules and CAI materials?) incorporated into different regions of the ordinary <span class="hlt">chondrite</span> parent bodies. The observed variations of Th/U, Nd/U, or Ce/U suggest that measurements of Pu/U on any single equilibrated ordinary <span class="hlt">chondrite</span> specimen, such as St. Se??verin, should statistically be within ??20-30% of the average solar system value, although it is also clear that anomalous samples exist. ?? 1990.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26PSL.454..213T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26PSL.454..213T"><span id="translatedtitle">Evidence for impact induced pressure gradients on the <span class="hlt">Allende</span> CV3 parent body: Consequences for fluid and volatile transport</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tait, Alastair W.; Fisher, Kent R.; Srinivasan, Poorna; Simon, Justin I.</p> <p>2016-11-01</p> <p><span class="hlt">Carbonaceous</span> <span class="hlt">chondrites</span>, 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 <span class="hlt">Allende</span> (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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22020377','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22020377"><span id="translatedtitle">AMMONIA IN THE EARLY SOLAR SYSTEM: AN ACCOUNT FROM <span class="hlt">CARBONACEOUS</span> METEORITES</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Pizzarello, S.; Williams, L. B.</p> <p>2012-04-20</p> <p>This study presents a survey of abundance distribution and isotopic composition of the ammonia found incorporated in the kerogen-like insoluble material of selected <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> meteorites; the ammonia was released upon hydrothermal treatment at 300 Degree-Sign C and 100 MPa. With the exception of <span class="hlt">Allende</span>, a metamorphosed and highly altered stone, all the insoluble organic materials (IOM) of the meteorites analyzed released significant amounts of ammonia, which varied from over 4 {mu}g mg{sup -1} for the Orgueil IOM to 0.5 {mu}g mg{sup -1} for that of Tagish Lake; the IOM of the pristine Antarctica find GRA95229 remains the most rich in freeable ammonia with 10 {mu}g mg{sup -1}. While the amounts of IOM bound ammonia do not appear to vary between meteorites with a recognizable trend, a possible consequence of long terrestrial exposure of some of the stones, we found that the {delta}{sup 15}N composition of the ammonia-carrying materials is clearly distinctive of meteorite types and may reflect a preservation of the original {sup 15}N distribution of pre- and proto-solar materials.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995Metic..30S.530K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995Metic..30S.530K"><span id="translatedtitle">Alteration and Dehydration in the Parent Asteroid of <span class="hlt">Allende</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krot, A. N.; Scott, E. R. D.; Zolensky, M. E.</p> <p>1995-09-01</p> <p>CV3 <span class="hlt">chondrites</span> experienced various degrees of late-stage modification, including: fayalitic rims around forsteritic grains, secondary mineralization (e.g., nepheline, sodalite, magnetite) in CAIs and chondrules, and formation of phyllosilicates [1]. Our literature survey show that these secondary features probably have a related origin [2]. Although an asteroidal origin is generally accepted for most phyllosilicates [3] and proposed for magnetite [4], the other secondary features have been attributed to reactions of CV3 components with a hot (> 1500 K) and oxidized (H2O/H2 about 1) nebular gas [5]. The <span class="hlt">Allende</span> meteorite is considered to be a primitive CV3, because phyllosilicates are absent in the matrix and metamorphic effects are not apparent [6]. However, all other secondary features are well-developed. Studies of dark inclusions (DIs) in CV3s [7] provide a key to understanding the secondary features in <span class="hlt">Allende</span>. Mineralogical, chemical and isotopic data indicate that DIs and CV3s have related origins. Matrices of the DIs resemble the <span class="hlt">Allende</span> matrix, but the chondrules show a wider range of alteration textures. In some DIs, the chondrules have only fayalitic rims like those in <span class="hlt">Allende</span>, but in others there are chondrule-shaped regions of porous fayalitic olivine. In DIs of intermediate type, the chondrules consist of forsteritic cores, which have fayalitic rims, surrounded by porous fayalitic olivine. We conclude that the sequence observed among DIs reflects various degrees of replacement of chondrules by fayalitic olivine. The presence of veins of fayalitic olivine, nepheline and Ca-pyroxene throughout DIs [7] which experienced the most pervasive alteration argues for asteroidal processing of DIs. Like Kojima and Tomeoka [7], we infer that porous fayalitic olivine formed by metamorphic dehydration of phyllosilicates on an asteroid. We suggest that the <span class="hlt">Allende</span> host and <span class="hlt">Allende</span>-like DIs represent the initial stages of the alteration sequence from material similar</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9545215','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9545215"><span id="translatedtitle">Oxygen isotopic abundances in calcium- aluminum-rich inclusions from ordinary <span class="hlt">chondrites</span>: implications for nebular heterogeneity.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McKeegan, K D; Leshin, L A; Russell, S S; MacPherson, G J</p> <p>1998-04-17</p> <p>The oxygen isotopic compositions of two calcium-aluminum-rich inclusions (CAIs) from the unequilibrated ordinary <span class="hlt">chondrite</span> meteorites Quinyambie and Semarkona are enriched in 16O by an amount similar to that in CAIs from <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>. This may indicate that most CAIs formed in a restricted region of the solar nebula and were then unevenly distributed throughout the various <span class="hlt">chondrite</span> accretion regions. The Semarkona CAI is isotopically homogeneous and contains highly 16O-enriched melilite, supporting the hypothesis that all CAI minerals were originally 16O-rich, but that in most <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> inclusions some minerals exchanged oxygen isotopes with an external reservoir following crystallization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9742724','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9742724"><span id="translatedtitle">Observation of indigenous polycyclic aromatic hydrocarbons in 'giant' <span class="hlt">carbonaceous</span> antarctic micrometeorites.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Clemett, S J; Chillier, X D; Gillette, S; Zare, R N; Maurette, M; Engrand, C; Kurat, G</p> <p>1998-10-01</p> <p>Two-step laser desorption/laser ionization mass spectrometry (microL2 MS) was used to establish the nature and mass distribution of polycyclic aromatic hydrocarbons (PAHs) in fragments of fifteen 'giant' (approximately 200 microns) <span class="hlt">carbonaceous</span> Antarctic micrometeorites (AMMs). Detectable concentrations of PAHs were observed in all AMMs showing a fine-grained matrix. The range of integrated PAH signal intensities varied between samples by over two orders of magnitude. No evidence of contamination whilst in the Antarctic environment could be found. The dramatic variation of both PAH signal intensities and mass distributions between AMMs along with comprehensive contamination checks demonstrates that particles are not exposed to terrestrial PAHs at or above detection limits, either subsequent, during or prior to collection. Comparison of the observed PAH distributions with those measured in three <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> [Orgueil (CI1), Murchison (CM2) and <span class="hlt">Allende</span> (CV3)] under identical conditions demonstrated that marked differences exist in the trace organic composition of these two sources of extraterrestrial matter. In general, AMMs show a far richer distribution of unalkylated 'parent' PAHs with more extended alkylation series (replacement of -H with -(CH2)n-H; n = 1, 2, 3 ...). The degree of alkylation loosely correlates with a metamorphic index that represents the extent of frictional heating incurred during atmospheric entry. A search for possible effects of the chemical composition of the fine-grain matrix of host particles on the observed PAH distributions reveals that high degrees of alkylation are associated with high Na/Si ratios. These results, in addition to other observations by Maurette, indicate that 'giant' micrometeorites survive hypervelocity (> or = 11 km s-1) atmospheric entry unexpectedly well. Because such micrometeorites are believed to represent the dominant mass fraction of extraterrestrial material accreted by the Earth, they may have</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140007365','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140007365"><span id="translatedtitle">Aqueous Alteration of Enstatite <span class="hlt">Chondrites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zolensky, M. E.; Ziegler, K.; Weisberg, M. K.; Gounelle, M.; Berger, E. L.; Le, L.; Ivanov, A.</p> <p>2014-01-01</p> <p>The Kaidun meteorite is different from all other meteorites [1], consisting largely of a mixture of “incompatible” types of meteoritic material – <span class="hlt">carbonaceous</span> and enstatite <span class="hlt">chondrites</span>, i.e. corre-sponding to the most oxidized and the most reduced samples of meteorite materials, including CI1, CM1-2, CV3, EH3-5, and EL3. In addition to these, minor amounts of ordinary and R <span class="hlt">chondrites</span> are present. In addition, approximately half of the Kaidun lithologies are new materials not known as separate meteorites. Among these are aqueously altered enstatite <span class="hlt">chondrites</span> [1], which are of considerable interest because they testify that not all reduced asteroids escaped late-stage oxidation, and hydrolysis, and also because hydrated poorly crystalline Si-Fe phase, which in turn is re-placed by serpentine (Figs 3-5). In the end the only indication of the original presence of metal is the re-sidual carbides. In other enstatite <span class="hlt">chondrite</span> lithogies (of uncertain type) original silicates and metal have been thoroughly replaced by an assemblage of authi-genic plagioclase laths, calcite boxwork, and occasion-al residual grains of silica, Cr-rich troilite, ilmenite, and rare sulfides including heideite (Fig. 6). Fe and S have been largely leached from the rock (Fig. 4). Again the accessory phases are the first clue to the original character of the rock, which can be verified by O isotopes. It is fortunate that Kaidun displays every step of the alteration process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19800018760','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19800018760"><span id="translatedtitle">On the chemical composition of L-<span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Neal, C. W.; Dodd, R. T.; Jarosewich, E.; Lipschutz, M. E.</p> <p>1980-01-01</p> <p>Radiochemical neutron activation analysis of Ag, As, Au, Bi, Co, Cs, Ga, In, Rb, Sb, Te, Tl, and Zn and major element data in 14 L4-6 and 3 LL5 <span class="hlt">chondrites</span> indicates that the L group is unusually variable and may represent at least 2 subgroups differing in formation history. Chemical trends in the S/Fe rich subgroup support textural evidence indicating late loss of a shock formed Fe-Ni-S melt; the S/Fe poor subgroup seemingly reflects nebular fractionation only. Highly mobile In and Zn apparently reflect shock induced loss from L <span class="hlt">chondrites</span>. However, contrasting chemical trends in several L <span class="hlt">chondrite</span> sample sets indicate that these meteorites constitute a more irregular sampling of, or more heterogeneous parent material than do <span class="hlt">carbonaceous</span> or enstatite <span class="hlt">chondrites</span>. Data for 15 <span class="hlt">chondrites</span> suggest higher formation temperatures and/or degrees of shock than for LL5 <span class="hlt">chondrites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014M%26PS...49.1250M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014M%26PS...49.1250M"><span id="translatedtitle">The formation of Ca-, Fe-rich silicates in reduced and oxidized CV <span class="hlt">chondrites</span>: The roles of impact-modified porosity and permeability, and heterogeneous distribution of water ices</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>MacPherson, Glenn J.; Krot, Alexander N.</p> <p>2014-07-01</p> <p>CV (Vigarano type) <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>, comprising <span class="hlt">Allende</span>-like (CVoxA) and Bali-like (CVoxB) oxidized and reduced (CVred) subgroups, experienced differing degrees of fluid-assisted thermal and shock metamorphism. The abundance and speciation of secondary minerals produced during asteroidal alteration differ among the subgroups: (1) ferroan olivine and diopside-hedenbergite solid solution pyroxenes are common in all CVs; (2) nepheline and sodalite are abundant in CVoxA, rare in CVred, and absent in CVoxB; (3) phyllosilicates and nearly pure fayalite are common in CVoxB, rare in CVred, and virtually absent in CVoxA; (4) andradite, magnetite, and Fe-Ni-sulfides are common in oxidized CVs, but rare in reduced CVs; the latter contain kirschsteinite instead. Thus, a previously unrecognized correlation exists between meteorite bulk permeabilities and porosities with the speciation of the Ca-, Fe-rich silicates (pyroxenes, andradite, kirschsteinite) among the CVox and CVred meteorites. The extent of secondary mineralization was controlled by the distribution of water ices, permeability, and porosity, which in turn were controlled by impacts on the asteroidal parent body. More intense shock metamorphism in the region where the reduced CVs originated decreased their porosity and permeability while simultaneously expelling intergranular ices and fluids. The mineralogy, petrography, and bulk chemical compositions of both the reduced and oxidized CV <span class="hlt">chondrites</span> indicate that mobile elements were redistributed between Ca,Al-rich inclusions, dark inclusions, chondrules, and matrices only locally; there is no evidence for large-scale (>several cm) fluid transport. Published 53Mn-53Cr ages of secondary fayalite in CV, CO, and unequilibrated ordinary <span class="hlt">chondrites</span>, and carbonates in CI, CM, and CR <span class="hlt">chondrites</span> are consistent with aqueous alteration initiated by heating of water ice-bearing asteroids by decay of 26Al, not shock metamorphism.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9774267','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9774267"><span id="translatedtitle">Oxygen reservoirs in the early solar nebula inferred from an <span class="hlt">allende</span> CAI</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Young; Russell</p> <p>1998-10-16</p> <p>Ultraviolet laser microprobe analyses of a calcium-aluminum-rich inclusion (CAI) from the <span class="hlt">Allende</span> meteorite suggest that a line with a slope of exactly 1.00 on a plot of delta17O against delta18O represents the primitive oxygen isotope reservoir of the early solar nebula. Most meteorites are enriched in 17O and 18O relative to this line, and their oxygen isotope ratios can be explained by mass fractionation or isotope exchange initiating from the primitive reservoir. These data establish a link between the oxygen isotopic composition of the abundant ordinary <span class="hlt">chondrites</span> and the primitive 16O-rich component of CAIs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9841405','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9841405"><span id="translatedtitle">Oxygen reservoirs in the early solar nebula inferred from an <span class="hlt">Allende</span> CAI.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Young, E D; Russell, S S</p> <p>1998-10-16</p> <p>Ultraviolet laser microprobe analyses of a calcium-aluminum-rich inclusion (CAI) from the <span class="hlt">Allende</span> meteorite suggest that a line with a slope of exactly 1.00 on a plot of delta (17)O against delta (18)O represents the primitive oxygen isotope reservoir of the early solar nebula. Most meteorites are enriched in (17)O and (18)O relative to this line, and their oxygen isotope ratios can be explained by mass fractionation or isotope exchange initiating from the primitive reservoir. These data establish a link between the oxygen isotopic composition of the abundant ordinary <span class="hlt">chondrites</span> and the primitive (16)O-rich component of CAIs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140000408','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140000408"><span id="translatedtitle">Trace Element Abundances in an Unusual Hibonite-Perovskite Refractory Inclusion from <span class="hlt">Allende</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mane, Prajkta; Wadhwa, M.; Keller, L. P.</p> <p>2013-01-01</p> <p>Calcium-aluminum-rich refractory inclusions (CAIs) are thought to be the first-formed solids in the Solar protoplanetary disk and can provide information about the earliest Solar System processes (e.g., [1]). A hibonite-perovskitebearing CAI from the <span class="hlt">Allende</span> CV3 <span class="hlt">chondrite</span> (SHAL, [2]) contains a single of 500 micrometers hibonite grain and coarse-grained perovskite. The mineralogy and oxygen isotopic composition of this CAI shows similarities with FUN inclusions, especially HAL [2]. Here we present trace element abundances in SHAL.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19770060133&hterms=nickel+sulfide+formation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dnickel%2Bsulfide%2Bformation','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19770060133&hterms=nickel+sulfide+formation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dnickel%2Bsulfide%2Bformation"><span id="translatedtitle">Molybdenite in calcium-aluminum-rich inclusions in the <span class="hlt">Allende</span> meteorite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fuchs, L. H.; Blander, M.</p> <p>1977-01-01</p> <p>The first observations of molybdenite in a meteorite have been made in two Ca-Al-rich inclusions in the <span class="hlt">Allende</span> <span class="hlt">chondrite</span>. The mineral occurs as single individuals completely enclosed in high Ni metal (62-64.5 wt. % Ni). The association with refractories is consistent with thermodynamic calculations which predict that Mo is a high temperature condensate even when nucleation constraints are imposed on the formation of a metal phase. Kinetic factors (including nucleation constraints) appear to have played an important role in the formation of molybdenite and the associated sulfides, magnetite and high nickel metal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014LPICo1800.5403M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014LPICo1800.5403M"><span id="translatedtitle">Zr Isotope Systematics of <span class="hlt">Allende</span> CAIs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mane, P.; Romaniello, S. J.; Brennecka, G. A.; Williams, C. D.; Wadhwa, M.</p> <p>2014-09-01</p> <p>We report high precision Zr isotopic measurements of CAIs from <span class="hlt">Allende</span> CV3 meteorite. Our results indicate a uniform Zr isotopic composition in the CAI forming region, with enrichment in r-process isotope 96Zr.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010102851','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010102851"><span id="translatedtitle">Organic Chemistry of <span class="hlt">Carbonaceous</span> Meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cronin, John R.</p> <p>2001-01-01</p> <p>Chiral and carbon-isotopic analyses of isovaline have been carried out on numerous samples of the Murchison and one sample of the Murray <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span>. The isovaline was found to be heterogeneous with regard to enantiomeric excess (ee) both between samples and within a single Murchison sample. L-Excesses ranging from 0 to 15% were observed. The isovaline delta(sup 13) C was found to be about +18%. No evidence was obtained suggesting terrestrial contamination in the more abundant L-enantiomer. A correlation was observed between isovaline (also alpha - aminoisobutyric acid) concentration and PCP content of five CM <span class="hlt">chondrites</span>. It is suggested that isovaline, along with other meteoritic a-methyl amino acids with ee, are of presolar origin. The possible formation of ee in extraterrestrial amino acids by exposure to circularly polarized light or by magnetochiral photochemistry is discussed. Key words: Murchison meteorite, Murray meteorite, amino acids, isovaline, chirality, carbon isotopes, PCP.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850018242','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850018242"><span id="translatedtitle">Refractory inclusions in the Ornans C30 <span class="hlt">chondrite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Davis, A. M.</p> <p>1985-01-01</p> <p>Several types of metedorites contain unusual objects 10 micrometers to 2 centimeters across that are enriched in refractory elements such as calcium, aluminum and titanium. These objects, commonly known as refractory inclusions, are most abundant in the meteorites known as <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>. The refractory inclusions that have been found in the Ornans metedorite, a member of a little-studied group of <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> are described. Some refractory inclusions in Ornans resemble those found in other meteorites, while others are unlike any seen before. The unusual inclusions in Ornans contain minerals with extraordinary enrichments in highly refractory elements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1022885','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1022885"><span id="translatedtitle">Renewed Search for FUN (Fractionated and Unidentified Nuclear Effects) in Primitive <span class="hlt">Chondrites</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tollstrup, D L; Wimpenny, J B; Yin, Q -; Ebel, D S; Jacobsen, B; Hutcheon, I D</p> <p>2011-04-07</p> <p>Ca-Al-rich inclusions (CAIs) found in primitive <span class="hlt">chondrites</span> record processes and conditions of the earliest solar system as they are the oldest known solid objects formed in the solar system [1,2]. CAIs with fractionation and unidentified nuclear anomalies (FUN CAIs; [3]) are very rare and thusfar found exclusively in CV <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> (e.g., <span class="hlt">Allende</span> and Vigarano)[4]. FUN CAIs are characterized by large nucleosynthetic anomalies in several elements (Ca, Ti, Si, Sr, Ba, Nd, and Sm), large mass-dependant isotope fractionation (Mg, Si, and O), and very little initial {sup 26}Al [4,5 and reference therein]. Formation of FUN CAIs by thermal processing of presolar dust aggregates prior to the injection of {sup 26}Al into the protoplanetary disk has been proposed. More recently [5] proposed that FUN CAIs formed from a protosolar molecular cloud after injection of {sup 26}Al but before {sup 26}Al and {sup 27}Al were completely homogenized. Therefore discovering more FUN CAIs to perform U-Pb and other short-lived chronometric dating will provide key constraints on the age of the solar system, the isotopic composition of the protosolar molecular cloud, the earliest stages of the thermal processing in the solar system and the timing of {sup 26}Al and other short-lived radionuclide injection into the nascent solar system. Most known FUN CAIs were discovered and studied > 30 yr ago, and their isotope ratios determined using thermal ionization mass spectrometry (TIMS). Most of these FUN CAIs were almost or entirely consumed during their respective analyses. [5] recently identified a new FUN CAI (NWA 779 KS-1) based on O and Mg isotope ratios determined by SIMS and MCICPMS, respectively. We have initiated a systematic search for FUN CAIs in primitive <span class="hlt">chondrites</span>, taking advantage of the large mass-dependant Mg isotope effects known for FUN inclusions with little or no inferred {sup 26}Al. Our strategy is to use newly developed sample cells capable of holding very large</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70033772','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70033772"><span id="translatedtitle">Fe-Ni metal in primitive <span class="hlt">chondrites</span>: Indicators of classification and metamorphic conditions for ordinary and CO <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Kimura, M.; Grossman, J.N.; Weisberg, M.K.</p> <p>2008-01-01</p> <p>We report the results of our petrological and mineralogical study of Fe-Ni metal in type 3 ordinary and CO <span class="hlt">chondrites</span>, and the ungrouped <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> Acfer 094. Fe-Ni metal in ordinary and CO <span class="hlt">chondrites</span> occurs in chondrule interiors, on chondrule surfaces, and as isolated grains in the matrix. Isolated Ni-rich metal in <span class="hlt">chondrites</span> of petrologic type lower than type 3.10 is enriched in Co relative to the kamacite in chondrules. However, Ni-rich metal in type 3.15-3.9 <span class="hlt">chondrites</span> always contains less Co than does kamacite. Fe-Ni metal grains in chondrules in Semarkona typically show plessitic intergrowths consisting of submicrometer kamacite and Ni-rich regions. Metal in other type 3 <span class="hlt">chondrites</span> is composed of fine- to coarse-grained aggregates of kamacite and Ni-rich metal, resulting from metamorphism in the parent body. We found that the number density of Ni-rich grains in metal (number of Ni-rich grains per unit area of metal) in chondrules systematically decreases with increasing petrologic type. Thus, Fe-Ni metal is a highly sensitive recorder of metamorphism in ordinary and <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>, and can be used to distinguish petrologic type and identify the least thermally metamorphosed <span class="hlt">chondrites</span>. Among the known ordinary and CO <span class="hlt">chondrites</span>, Semarkona is the most primitive. The range of metamorphic temperatures were similar for type 3 ordinary and CO <span class="hlt">chondrites</span>, despite them having different parent bodies. Most Fe-Ni metal in Acfer 094 is martensite, and it preserves primary features. The degree of metamorphism is lower in Acfer 094, a true type 3.00 <span class="hlt">chondrite</span>, than in Semarkona, which should be reclassified as type 3.01. ?? The Meteoritical Society, 2008.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19890040136&hterms=Keynes&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DKeynes','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19890040136&hterms=Keynes&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DKeynes"><span id="translatedtitle">Primitive material surviving in <span class="hlt">chondrites</span> - Matrix</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Scott, E. R. D.; Barber, D. J.; Alexander, C. M.; Hutchinson, R.; Peck, J. A.</p> <p>1988-01-01</p> <p>A logical place to search for surviving pristine nebular material is in the fine-grained matrices of ordinary and <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> of petrographic type 3. Unfortunately, many of these <span class="hlt">chondrites</span> have experienced brecciation, thermal metamorphism, and aqueous alteration, so that interpreting individual features in terms of specific nebular conditions and/or processes is difficult. It follows that the origin and evolutionary history of such matrix phases are controversial, and a consensus is difficult to define. In this chapter, therefore, after summarizing the salient mineralogical, petrographic, chemical, and isotopic features of matrix in apparently primitive <span class="hlt">chondrites</span>, an attempt is made to provide an overview both of areas of agreement and of topics that are currently in dispute.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992Metic..27..199A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992Metic..27..199A"><span id="translatedtitle">The Effects of Saharan Weathering on Light Element Contents of Various Primitive <span class="hlt">Chondrites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ash, R. D.; Pillinger, C. T.</p> <p>1992-07-01</p> <p>In recent years the Sahara Desert, particularly the Acfer region, has proven itself a rich source of meteoritic material, with over 400 samples from North Africa now residing in research laboratories. Among the samples retrieved has been a number of primitive <span class="hlt">chondrites</span>, including CVs, CRs, COs, an odd CM/CO specimen, and several fragments similar to the "unique" <span class="hlt">chondrite</span> ALH 85085 and a type 3.0-3.2 ordinary <span class="hlt">chondrite</span>. Samples of each of these have been analyzed for carbon content and delta^13C and some for nitrogen and hydrogen content, delta^5N and deltaD. Each of these elements shows a lower concentration in the Saharan samples than those determined for non-Saharan, including Antarctic samples of the same group. Carbon. The carbon content of the Saharan <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> analyzed were between 25 and 50% of the mean of the non-Saharan members of the group (the one exception is <span class="hlt">Allende</span>, which is known to have a lower carbon content that any other members of the CV group). Stepped combustion showed that a low organic carbon content of these samples was the cause of the overall carbon depletion. Nitrogen. The nitrogen contents of the Acfer region CR <span class="hlt">chondrites</span> was substantially lower than that of their non-Saharan equivalents. The nitrogen of the CR <span class="hlt">chondrites</span> is isotopically distinct from terrestrial samples and from other <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> in that it is highly enriched in ^15N. The isotopic composition of the Saharan samples shows no gross difference in the delta^15N, but there is some internal variation, due to differential weathering and the rusting of metal leading to the presence of trapped atmospheric nitrogen and consequently the delta^15N becoming variably lighter. Hydrogen. The hydrogen contents of the Saharan CR <span class="hlt">chondrites</span> and the 3.0-3.2 ordinary <span class="hlt">chondrite</span> Adrar 003 were found to be lower than the non-Saharan counterparts: The deltaD of the samples were isotopically normal quite unlike their non-Saharan counterparts, which are known to be</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980004741','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980004741"><span id="translatedtitle">Workshop on Parent-Body and Nebular Modification of <span class="hlt">Chondritic</span> Materials</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zolensky, M. E. (Editor); Krot, A. N. (Editor); Scott, E. R. D. (Editor)</p> <p>1997-01-01</p> <p>Topics considered include: thermal Metamorphosed Antarctic CM and CI <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrites</span> in Japanese Collections, and Transformation Processes of Phyllosilicates; use of Oxygen Isotopes to Constrain the Nebular and Asteroidal Modification of <span class="hlt">Chondritic</span> Materials; effect of Revised Nebular Water Distribution on Enstatite <span class="hlt">Chondrite</span> 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) <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrite</span>: Nebular and Parent-Body Features; rubidium-Strontium Isotopic Systematic of Chondrules from the Antarctic CV <span class="hlt">Chondrites</span> Yamato 86751 and Yamato 86009: Additional Evidence for Late Parent-Body Modification; oxygen-Fugacity Indicators in <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrites</span>: Parent-Body Alteration or High-Temperature Nebular Oxidation; thermodynamic Modeling of Aqueous Alteration in CV <span class="hlt">Chondrites</span>; asteroidal Modification of C and O <span class="hlt">Chondrites</span>: Myths and Models; oxygen Fugacity in the Solar Nebular; and the History of Metal and Sulfides in <span class="hlt">Chondrites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015E%26PSL.428..304P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015E%26PSL.428..304P"><span id="translatedtitle">Comment on "Hydrothermal preparation of analogous matrix minerals of CM <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> from metal alloy particles" by Y. Peng and Y. Jing [Earth Planet. Sci. Lett. 408 (2014) 252-262</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pignatelli, Isabella; Vacher, Lionel G.; Marrocchi, Yves</p> <p>2015-10-01</p> <p>Peng and Jing (2014) recently reported the results of hydrothermal experiments designed to produce synthetic tochilinite/cronstedtite assemblages analogous to those found in the matrix of CM <span class="hlt">chondrites</span> (Tomeoka and Buseck, 1982, 1983a, 1983b, 1985; Mackinnon and Zolensky, 1984; Zolensky and Mackinnon, 1986; Rubin et al., 2007; Bourot-Denise et al., 2010; Hewins et al., 2014; Marrocchi et al., 2014). The assemblage was obtained from an alloyed metal particle mixture of Fe, Mg, Al, Si, Cr and Ni under basic, reducing and S2--rich conditions. The hydrothermal syntheses were conducted in Teflon-lined stainless-steel autoclaves at temperature of 106-160 °C for short-duration runs and at 153 °C for long-duration runs. The phases in the assemblage were characterized by XRD and TEM, but only the analytical results of long-duration runs were reported in the article and in the Appendix as supplementary material. The phases identified were: cronstedtite and tochilinite (both present in all run products), tochilinite-cronstedtite intergrowths, polyhedral serpentine, a chrysotile-like phase, nanotube-like structures, and lizardite-like and brucite-like phases. Based on their experimental results, the authors put forward a hypothesis to explain the formation of matrix minerals in CM <span class="hlt">chondrites</span> proposing that the precursors may be nanometer- to micrometer-sized particles of metal alloys that were altered at low temperatures by interaction with S-rich water under reducing and dynamic pressurized conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940016169&hterms=nazarov&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dnazarov','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940016169&hterms=nazarov&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dnazarov"><span id="translatedtitle"><span class="hlt">Carbonaceous</span> xenoliths from the Erevan howardite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nazarov, M. A.; Brandstaetter, F.; Kurat, G.</p> <p>1993-01-01</p> <p>Preliminary studies of the Erevan howardite showed that the meteorite is a polymict breccia. We report on our study of CM-type <span class="hlt">carbonaceous</span> xenoliths. All of these clasts are enriched in tochilinite and carbonate inclusion as compared to CM <span class="hlt">chondrites</span>. They also contain a new, P-rich sulphide beside pentlandite. The P-rich sulphide represents a new type of P-bearing phases. It indicates a chalcophile behavior of P under certain nebular conditions.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160011249','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160011249"><span id="translatedtitle">The Nature of C Asteroid Regolith Revealed from the Jbilet Winselwan CM <span class="hlt">Chondrite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zolensky, Michael; Mikouchi, Takashi; Hagiya, Kenji; Ohsumi, Kazumasa; Komatsu, Mutsumi; Chan, Queenie H. S.; Le, Loan; Kring, David; Cato, Michael; Fagan, Amy L.</p> <p>2016-01-01</p> <p>C-class asteroids frequently exhibit reflectance spectra consistent with thermally metamorphosed <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>, or a mixture of phyllosilicate-rich material along with regions where they are absent. One particularly important example appears to be asteroid 162173 Ryugu, the target of the Hayabusa 2 mission, although most spectra of Ryugu are featureless, suggesting a heterogeneous regolith. Here we explore an alternative cause of dehydration of regolith of C-class asteroids - impact shock melting. Impact shock melting has been proposed to ex-plain some mineralogical characteristics of CB <span class="hlt">chondrites</span>, but has rarely been considered a major process for hydrous <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1980GeoRL...7..493L&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1980GeoRL...7..493L&link_type=ABSTRACT"><span id="translatedtitle">Oxygen isotopic anomalies in <span class="hlt">Allende</span> inclusion HAL</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, T.; Mayeda, T. K.; Clayton, R. N.</p> <p>1980-07-01</p> <p>An oxygen isotopic study which demonstrates the <span class="hlt">Allende</span> inclusion HAL is a FUN object is discussed; the hibonite core, black inner rim and fine-grained outer rim have beem sampled. The oxygen in HAL is found to be heterogeneous, the rim samples having oxygen compositions similar to that of melilites and alteration products in other <span class="hlt">Allende</span> inclusions including the FUN inclusion EK1-4-1, while the oxygen in the hibonite core shows the most extreme deviation from the AD line so far observed. The oxygen in HAL hibonite, in ED1-4-1 spinel and in spinels of usual <span class="hlt">Allende</span> inclusions form an approximate linear array with a slope close to 1/2. With regard to the fractionation process, it is noted that the fractionation per amu for various elements does not correlate inversely with mass and that fractionation is elementally selective, probably according to volatility.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6595786','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6595786"><span id="translatedtitle">Zinc isotope anomalies. [In <span class="hlt">Allende</span> meteorite</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Volkening, J.; Papanastassiou, D.A. )</p> <p>1990-07-01</p> <p>The Zn isotope composition in refractory-element-rich inclusions of the <span class="hlt">Allende</span> meteorite are determined. Typical inclusions contain normal Zn. A unique inclusion of the <span class="hlt">Allende</span> meteorite shows an excess for Zn-66 of 16.7 + or - 3.7 eu (1 eu = 0.01 percent) and a deficit for Zn-70 of 21 + or - 13 eu. These results indicate the preservation of exotic components even for volatile elements in this inclusion. The observed excess Zn-66 correlates with excesses for the neutron-rich isotopes of Ca-48, Ti-50, Cr-54, and Fe-58 in the same inclusion. 32 refs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19890030095&hterms=chromium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dchromium','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19890030095&hterms=chromium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dchromium"><span id="translatedtitle">Nickel and chromium isotopes in <span class="hlt">Allende</span> inclusions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Birck, J. L.; Lugmair, G. W.</p> <p>1988-01-01</p> <p>High-precision nickel and chromium isotopic measurements were carried out on nine <span class="hlt">Allende</span> inclusions. It is found that Ni-62, Ni-64, excesses are present in at least three of the samples. The results suggest that the most likely mechanism for the anomalies is a neutron-rich statistical equilibrium process. An indication of elevated Ni-60 is found in almost every inclusion measured. This effect is thought to be related to the decay of now extinct Fe-60. An upper limit of 1.6 X 10 to the -6th is calculated for the Fe-60/Fe-56 ratio at the time these <span class="hlt">Allende</span> inclusions crystallized.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19900054815&hterms=zinc&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dzinc','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19900054815&hterms=zinc&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dzinc"><span id="translatedtitle">Zinc isotope anomalies. [in <span class="hlt">Allende</span> meteorite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Volkening, J.; Papanastassiou, D. A.</p> <p>1990-01-01</p> <p>The Zn isotope composition in refractory-element-rich inclusions of the <span class="hlt">Allende</span> meteorite are determined. Typical inclusions contain normal Zn. A unique inclusion of the <span class="hlt">Allende</span> meteorite shows an excess for Zn-66 of 16.7 + or - 3.7 eu (1 eu = 0.01 percent) and a deficit for Zn-70 of 21 + or - 13 eu. These results indicate the preservation of exotic components even for volatile elements in this inclusion. The observed excess Zn-66 correlates with excesses for the neutron-rich isotopes of Ca-48, Ti-50, Cr-54, and Fe-58 in the same inclusion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940011939','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940011939"><span id="translatedtitle">Refractory precursor components in an <span class="hlt">Allende</span> ferromagnesian chondrule</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Misawa, Keiji; Fujita, Takashi; Kitamura, Masao; Nakamura, Noboru</p> <p>1993-01-01</p> <p>Chemical and petrological studies of chondrules revealed that they were formed through melting of pre-existing solid precursor materials, and that one of the refractory lithophile precursors was a high temperature condensate from the nebular gas and related to Ca, Al-rich inclusions (CAIs). Sheng et al. found relict spinel grains with isotopically fractionated Mg in plagioclase-olivine inclusions from CV <span class="hlt">chondrites</span> and suggested that the major fractionation processes were common to CAIs and chondrules. We have determined the Mg isotopic compositon of five barred olivine chondrules and one coarse-grained rim from the <span class="hlt">Allende</span> (CV3) meteorite. A reproducibility of instrumental isotope fractionation is plus or minus 2 per thousand per amu. The precision of the Mg-26/Mg-24 data after normalization for mass fractionation can be as good as 0.5 per thousand (2 sigma(mean)). The Mg analytical results are given and indicate that delta Mg-25/Mg-24 and sigma Mg-26 of the chondrules are normal within errors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20050162214&hterms=Radioactivity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DRadioactivity','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20050162214&hterms=Radioactivity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DRadioactivity"><span id="translatedtitle"><span class="hlt">Chondrites</span> and the Protoplanetary Disk, Part 3</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p>Contents include the following: Ca-, Al-Rich Inclusions and Ameoboid Olivine Aggregates: What We Know and Don t Know About Their Origin. Aluminium-26 and Oxygen Isotopic Distributions of Ca-Al-rich Inclusions from Acfer 214 CH <span class="hlt">Chondrite</span>. The Trapping Efficiency of Helium in Fullerene and Its Implicatiion to the Planetary Science. Constraints on the Origin of <span class="hlt">Chondritic</span> Components from Oxygen Isotopic Compositions. Role of Planetary Impacts in Thermal Processing of <span class="hlt">Chondrite</span> Materials. Formation of the Melilite Mantle of the Type B1 CAIs: Flash Heating or Transport? The Iodine-Xenon System in Outer and Inner Portions of Chondrules from the Unnamed Antarctic LL3 <span class="hlt">Chondrite</span>. Nucleosynthesis of Short-lived Radioactivities in Massive Stars. The Two-Fluid Analysis of the Kelvin-Helmholtz Instability in the Dust Layer of a Protoplanetary Disk: A Possible Path to the Planetesimal Formation Through the Gravitational Instability. Shock-Wave Heating Model for Chonodrule Formation: Heating Rate and Cooling Rate Constraints. Glycine Amide Hydrolysis with Water and OH Radical: A Comparative DFT Study. Micron-sized Sample Preparation for AFM and SEM. AFM, FE-SEM and Optical Imaging of a Shocked L/LL <span class="hlt">Chondrite</span>: Implications for Martensite Formation and Wave Propagation. Infrared Spectroscopy of <span class="hlt">Chondrites</span> and Their Components: A Link Between Meteoritics and Astronomy? Mid-Infrared Spectroscopy of CAI and Their Mineral Components. The Origin of Iron Isotope Fractionation in Chondrules, CAIs and Matrix from <span class="hlt">Allende</span> (CV3) and Chainpur (LL3) <span class="hlt">Chondrites</span>. Protoplanetary Disk Evolution: Early Results from Spitzer. Kinetics of Evaporation-Condensation in a Melt-Solid System and Its Role on the Chemical Composition and Evolution of Chondrules. Oxygen Isotope Exchange Recorded Within Anorthite Single Crystal in Vigarano CAI: Evidence for Remelting by High Temperature Process in the Solar Nebula. Chondrule Forming Shock Waves in Solar Nebula by X-Ray Flares. Organic Globules with Anormalous</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995Metic..30Q.569R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995Metic..30Q.569R"><span id="translatedtitle">Variations of <span class="hlt">Chondrite</span> Properties with Heliocentric Distance</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rubin, A. E.; Wasson, J. T.</p> <p>1995-09-01</p> <p>There are 12 well-established <span class="hlt">chondrite</span> groups distinguishable by significant compositional hiatus among their compositional and petrographic characteristics. Because each group represents a different parent asteroid, formed in a distinct nebular region (and/or at a particular time), it is plausible that <span class="hlt">chondrite</span> properties varied in a smooth fashion with heliocentric distance (HD). Oxidation state. Thermodynamic calculations indicate that the equilibrium FeO/(FeO+MgO) ratio increases with decreasing nebular temperature. Because the nebular temperature gradient decreased with HD, at all times inner nebular regions had a lower oxidation state than more distant regions. If the time of agglomeration increased with HD, outer-solar-system materials generally would have acquired more ferroan compositions. By these criteria we infer that enstatite <span class="hlt">chondrites</span> formed closer to the Sun, OC at intermediate HD, and R <span class="hlt">chondrites</span> and <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> still farther from the Sun. Oxygen isotopic composition. The nearer the Sun, the higher the nebular temperature and the larger the fraction of infalling interstellar material that evaporated; this resulted in greater equilibration with nebular gas and greater isotopic homogeneity. Because the Earth, Moon and EH-EL <span class="hlt">chondrites</span> lie on the terrestrial fractionation (TF) line on the standard three O-isotope diagram, and martian meteorites (Delta^(17)O=0.36 per mil) and eucrites (Delta^(17)O=-0.40 per mil) lie close to this line, we infer that the mean nebular (i.e., solar) O-isotopic composition was on or near the TF line. At >1 AU the absolute value of Delta^(17)O increased. We infer that EH and EL <span class="hlt">chondrites</span> formed at a HD <1 AU; H, L and LL <span class="hlt">chondrites</span> (mean Delta^(17)O = 0.73, 1.07 and 1.26 per mil) formed appreciably beyond Mars' distance of 1.5 AU (probably near 2.5 AU at the 3:1 Jupiter-period resonance); R <span class="hlt">chondrites</span> (Delta^(17)O ~2.9 per mil) and CR, CM, CO, CV and CK <span class="hlt">chondrites</span> (Delta^(17)O ~ -1.6, -2.3, -4.5, -3.4 and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920053698&hterms=CI&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DCI','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920053698&hterms=CI&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DCI"><span id="translatedtitle">CI <span class="hlt">chondrite</span>-like clasts in the Nilpena polymict ureilite - Implications for aqueous alteration processes in CI <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brearley, Adrian J.; Prinz, Martin</p> <p>1992-01-01</p> <p>Petrographic studies of Nilpena polymict ureilite have revealed the presence of small quantities of <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> matrix clasts. Detailed electron microprobe and TEM studies show that the chemistry and fine-scale mineralogy of one of these clasts is consistent with CI <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> matrix. Compared to Orgeuil, the phyllosilicate, sulfide, and oxide mineralogy suggests that the Nilpena clasts may represent a less altered type of CI matrix. It is suggested that increased oxidation and aqueous alteration of Nilpena-type materials could result in the formation of the type of mineral assemblage observed in Orgueil. Increased alteration produces progressive more Mg-rich phyllosilicates and more Fe(3+)-rich iron oxides, such as ferrihydrite. As a function of increased alteration, Ca is also progressively leached from the matrix material to form carbonate veins. The depletion of Ca in CI <span class="hlt">chondrite</span> matrices suggests the Ivuna and Alais may be intermediate in their degree of alteration to Nilpena and Orgueil.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeCoA.148..402V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.148..402V"><span id="translatedtitle">Replacement of olivine by serpentine in the Queen Alexandra Range 93005 <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> (CM2): Reactant-product compositional relations, and isovolumetric constraints on reaction stoichiometry and elemental mobility during aqueous alteration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Velbel, Michael A.; Tonui, Eric K.; Zolensky, Michael E.</p> <p>2015-01-01</p> <p>Isovolumetric replacement of euhedral and anhedral olivine by serpentine produced both centripetal and meshwork textures in the CM2 <span class="hlt">chondrites</span> ALH 81002 and Nogoya. The compositions of these textural varieties of serpentine are uniform within narrow limits within each previously studied meteorite, independent of the composition of olivine being replaced, and different between the two meteorites. In QUE 93005 (CM2), coarse olivines of widely varying compositions (Fo<76-99) are replaced in a texturally similar manner by compositionally uniform serpentine (Mg0.73±0.05Fe0.27±0.05)3Si2O5(OH)4. The narrow compositional range of serpentine replacing coarse olivine indicates that the aqueous solution from which the serpentine formed was compositionally uniform on scales at least as large as the meteorite (∼2.5 cm in longest dimension). Isovolumetric textures and compositional observations constrain elemental redistribution from coarse olivine to serpentine and to surrounding phases during serpentinization. Regardless of olivine's composition, isovolumetric replacement of coarse olivines by serpentine of the observed composition released more Mg and Si from olivine than was required to form the serpentine. Excess Mg and Si released by olivine destruction and not retained in serpentine were exported from the replaced volume. Olivines with different Fa/Fo proportions contributed different amounts of Fe and Mg to the serpentine. Ferroan olivines released more Fe than required to form the serpentines replacing them, so some of the Fe released from ferroan olivine was exported from the replaced volumes. Forsteritic olivines released less Fe than required to form the serpentines replacing them, so some Fe was imported into the replaced volumes augmenting the small amount of Fe released from forsteritic olivine. In QUE 93005 Fo83.8 is the threshold composition between Fe-exporting and Fe-importing behavior in individual olivine-serpentine pairs, which released exactly the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeCoA.169...99K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.169...99K"><span id="translatedtitle">26Al-26Mg chronology and oxygen isotope distributions of multiple melting for a Type C CAI from <span class="hlt">Allende</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kawasaki, Noriyuki; Kato, Chizu; Itoh, Shoichi; Wakaki, Shigeyuki; Ito, Motoo; Yurimoto, Hisayoshi</p> <p>2015-11-01</p> <p>Disequilibrium oxygen isotopic distributions of Ca-Al-rich inclusions (CAIs) correspond to multiple melting events in the solar nebula. 26Al-26Mg systematics may be applicable for age differences among such melting events. We have carried out a coordinated study of detailed petrographic observations and in-situ oxygen and magnesium isotope measurements for a Type C CAI, EK1-04-2, from the <span class="hlt">Allende</span> CV3 meteorite to determine the melting events and their ages. The CAI consists mainly of spinel, anorthite, olivine, and pyroxene, and has a core and mantle structure. Petrography of the core suggests that the crystallization sequence of the core minerals is from spinel, anorthite, olivine, and to pyroxene. The mantle has the same mineral assemblage as the core, and shows incomplete melting and solidification textures. Oxygen isotopic compositions of the minerals are distributed along the <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> anhydrous mineral (CCAM) line (δ18O = -44‰ to +9‰), which indicates to preserve a chemical disequilibrium status in the CAI. Spinel shows a 16O-rich signature (δ18O ∼ -43‰), while anorthite is 16O-poor (δ18O ∼ +8‰). Olivine and pyroxene in the core have the same oxygen isotopic composition (δ18O ∼ -15‰), which indicates their equilibrium. Olivine and pyroxene in the mantle have variable oxygen isotopic compositions and are slightly depleted in 16O (δ18O = -13‰ to -4‰) compared with the same minerals in the core. The 26Al-26Mg systematics is consistent with the disequilibrium status observed according to the petrography and oxygen isotopes. Spinel is plotted on a line of (26Al/27Al)0 = (3.5 ± 0.2) × 10-5, anorthite is plotted on a line of (-1 ± 5) × 10-7, and olivine and pyroxene in the core are plotted on a line of (-1 ± 7) × 10-6. Plots of olivine and pyroxene in the mantle are scattered below the isochron of these minerals in the core. This study indicates that the EK1-04-2 Type C CAI underwent multiple heating events after the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008E%26PSL.272..353J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008E%26PSL.272..353J"><span id="translatedtitle">26Al- 26Mg and 207Pb- 206Pb systematics of <span class="hlt">Allende</span> CAIs: Canonical solar initial 26Al/ 27Al ratio reinstated</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jacobsen, Benjamin; Yin, Qing-zhu; Moynier, Frederic; Amelin, Yuri; Krot, Alexander N.; Nagashima, Kazuhide; Hutcheon, Ian D.; Palme, Herbert</p> <p>2008-07-01</p> <p>The precise knowledge of the initial 26Al/ 27Al ratio [( 26Al/ 27Al) 0] is crucial if we are to use the very first solid objects formed in our Solar System, calcium-aluminum-rich inclusions (CAIs) as the "time zero" age-anchor and guide future work with other short-lived radio-chronometers in the early Solar System, as well as determining the inventory of heat budgets from radioactivities for early planetary differentiation. New high-precision multi-collector inductively-coupled plasma mass spectrometry (MC-ICP-MS) measurements of 27Al/ 24Mg ratios and Mg-isotopic compositions of nine whole-rock CAIs (six mineralogically characterized fragments and three micro-drilled inclusions) from the CV <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span>, <span class="hlt">Allende</span> yield a well-defined 26Al- 26Mg fossil isochron with an ( 26Al/ 27Al) 0 of (5.23 ± 0.13) × 10 - 5 . Internal mineral isochrons obtained for three of these CAIs ( A44A, AJEF, and A43) are consistent with the whole-rock CAI isochron. The mineral isochron of AJEF with ( 26Al/ 27Al) 0 = (4.96 ± 0.25) × 10 - 5 , anchored to our precisely determined absolute 207Pb- 206Pb age of 4567.60 ± 0.36 Ma for the same mineral separates, reinstate the "canonical" ( 26Al/ 27Al) 0 of 5 × 10 - 5 for the early Solar System. The uncertainty in ( 26Al/ 27Al) 0 corresponds to a maximum time span of ± 20 Ka (thousand years), suggesting that the <span class="hlt">Allende</span> CAI formation events were culminated within this time span. Although all <span class="hlt">Allende</span> CAIs studied experienced multistage formation history, including melting and evaporation in the solar nebula and post-crystallization alteration likely on the asteroidal parent body, the 26Al- 26Mg and U-Pb-isotopic systematics of the mineral separates and bulk CAIs behaved largely as closed-system since their formation. Our data do not support the "supra-canonical" 26Al/ 27Al ratio of individual minerals or their mixtures in CV CAIs, suggesting that the supra-canonical 26Al/ 27Al ratio in the CV CAIs may have resulted from post</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19840053953&hterms=Magnesium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DMagnesium','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19840053953&hterms=Magnesium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DMagnesium"><span id="translatedtitle">Ion microprobe magnesium isotope analysis of plagioclase and hibonite from ordinary <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hinton, R. W.; Bischoff, A.</p> <p>1984-01-01</p> <p>Ion and electron microprobes were used to examine Mg-26 excesses from Al-26 decay in four Al-rich objects from the type 3 ordinary hibonite clast in the Dhajala <span class="hlt">chondrite</span>. The initial Al-26/Al-27 ratio was actually significantly lower than Al-rich inclusions in <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>. Also, no Mg-26 excesses were found in three plagioclase-bearing chondrules that were also examined. The Mg-26 excesses in the hibonite <span class="hlt">chondrites</span> indicated a common origin for <span class="hlt">chondrites</span> with the excesses. The implied Al-26 content in a proposed parent body could not, however, be confirmed as a widespread heat source in the early solar system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920003701','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920003701"><span id="translatedtitle">Transmission electron microscopy of an interplanetary dust particle with links to CI <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Keller, Lindsay P.; Thomas, Kathie L.; Mckay, David S.</p> <p>1991-01-01</p> <p>The majority of hydrated interplanetary dust particles (IDPs) have compositions that resemble CI and CM <span class="hlt">chondrites</span>, however, their mineralogies are most similar to the fine grained material in certain altered type-3 <span class="hlt">carbonaceous</span> and ordinary <span class="hlt">chondrites</span>. During the transmission electron microscope studies of hydrated IDPs, a unique particle was discovered whose mineralogy is very similar to that reported from CI <span class="hlt">chondrites</span>. W7013F5 is the first IDP whose mineralogy and chemistry approximates that of CI <span class="hlt">chondrites</span>. The similarity in mineralogy and mineral chemistry suggests that W7013F5 was altered under conditions similar to those that existed on the CI parent bodies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeCoA.163...27Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.163...27Z"><span id="translatedtitle">Mineralogical anatomy and implications of a Ti-Sc-rich ultrarefractory inclusion from Sayh al Uhaymir 290 CH3 <span class="hlt">chondrite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Ai-Cheng; Ma, Chi; Sakamoto, Naoya; Wang, Ru-Cheng; Hsu, Wei-Biao; Yurimoto, Hisayoshi</p> <p>2015-08-01</p> <p>Titanium-rich minerals are common in Ca-Al-rich inclusions from primitive <span class="hlt">chondrites</span>. They are important not only for testing the condensation models for a gas with a solar composition, but also for constraining the redox conditions of the early solar nebula. In this study, we report the detailed mineralogical features and its oxygen isotope compositions of a Ti-Sc-rich ultrarefractory inclusion A0031 from a CH3 <span class="hlt">chondrite</span> Sayh al Uhaymir 290. The A0031 inclusion has a compact and layered texture with the interior consisting of panguite, Sc-rich anosovite, Ti-rich davisite, and anorthite. A few hexaferrum, perovskite, and spinel crystals are present as inclusions in these minerals. Outside of Ti-rich davisite are a layer of Al-Ti-rich diopside and two grains of enstatite. This texture strongly suggests that A0031 has a condensation origin. Panguite is its third occurrence in nature and similar in composition to the type panguite from the <span class="hlt">Allende</span> meteorite. Sc-rich anosovite in A0031 has a chemical formula of (Ti4+,Ti3+,Mg,Sc,Al)3O5 with the pseudobrookite structure. This is the second report of Ti3O5 in nature, but is the first description of anosovite formed in the solar nebula as an ultrarefractory phase. The discovery of Sc-rich anosovite in A0031 reveals the stability of Ti3O5 in the early solar nebula and supports the prediction of previous equilibrium condensation calculations. The panguite, Sc-rich anosovite, and Ti-rich davisite in A0031 show a large variation in Ti3+/Titot. The primitive nature of A0031 implies that the variations in Ti3+/Titot among different Ti-rich minerals are primary features. We propose that the distribution of Ti3+ and Ti4+ could be controlled mainly by their various competition abilities of incorporating into these Ti-Sc-Al-rich minerals. Similarity of Ti3+/Titot value between Ti-rich davisite from A0031 and those in other <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> indicates that most refractory inclusions might have formed in highly reducing nebular</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985GeCoA..49...89D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985GeCoA..49...89D"><span id="translatedtitle">The stable carbon isotopes in enstatite <span class="hlt">chondrites</span> and Cumberland Falls</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Deines, P.; Wickman, F. E.</p> <p>1985-01-01</p> <p>The carbon-isotopic composition (CIC) of the total carbon in the enstatite <span class="hlt">chondrites</span> Indarch, Abee, St. Marks, Pillistfer, Hvittis and Daniel's Kuil and the enstatite achondrite Cumberland Falls has been measured. The empirical relationship between CIC and total carbon content is distinct from that of <span class="hlt">carbonaceous</span> and ordinary <span class="hlt">chondrites</span>. Within the enstatite <span class="hlt">chondrite</span> group the average C-13 content increases with petrographic type: E4 less than E5 less than E6. Daniel's Kuil shows the largest C-13 enrichment in the bulk carbon of any meteorite. The CIC is most clearly correlated with the abundance of the elements Zn, Cd, and In. Insofar as these elements may hold the key to the understanding of enstatite <span class="hlt">chondrites</span>, more detailed combined CIC and trace-element studies of these meteorites will play an important role in the deciphering of their history.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007epsc.conf..898A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007epsc.conf..898A"><span id="translatedtitle">Terrestrial microbes in martian and <span class="hlt">chondritic</span> meteorites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Airieau, S.; Picenco, Y.; Andersen, G.</p> <p>2007-08-01</p> <p>Introduction: The best extraterrestrial analogs for microbiology are meteorites. The chemistry and mineralogy of Asteroid Belt and martian (SNC) meteorites are used as tracers of processes that took place in the early solar system. Meteoritic falls, in particular those of <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>, are regarded as pristine samples of planetesimal evolution as these rocks are primitive and mostly unprocessed since the formation of the solar system 4.56 billion years ago. Yet, questions about terrestrial contamination and its effects on the meteoritic isotopic, chemical and mineral characteristics often arise. Meteorites are hosts to biological activity as soon as they are in contact with the terrestrial biosphere, like all rocks. A wide biodiversity was found in 21 <span class="hlt">chondrites</span> and 8 martian stones, and was investigated with cell culture, microscopy techniques, PCR, and LAL photoluminetry. Some preliminary results are presented here. The sample suite included <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> of types CR, CV, CK, CO, CI, and CM, from ANSMET and Falls. Past studies documented the alteration of meteorites by weathering and biological activity [1]-[4]. Unpublished observations during aqueous extraction for oxygen isotopic analysis [5], noted the formation of biofilms in water in a matter of days. In order to address the potential modification of meteoritic isotopic and chemical signatures, the culture of microbial contaminating species was initiated in 2005, and after a prolonged incubation, some of the species obtained from cell culture were analyzed in 2006. The results are preliminary, and a systematic catalog of microbial contaminants is developing very slowly due to lack of funding. Methods: The primary method was cell culture and PCR. <span class="hlt">Chondrites</span>. <span class="hlt">Chondritic</span> meteorite fragments were obtained by breaking stones of approximately one gram in sterile mortars. The core of the rocks, presumably less contaminated than the surface, was used for the present microbial study, and the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6576428','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6576428"><span id="translatedtitle">Alkali (Rb/K) abundances in <span class="hlt">Allende</span> barred-olivine chondrules - Implications for the melting conditions of chondrules</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Matsuda, Hitoshi; Nakamura, Noboru; Noda, Shinji )</p> <p>1990-06-01</p> <p>Twenty five petrographically characterized chondrules, including 18 barred olivine (BO) chondrules from the <span class="hlt">Allende</span> (CV3) meteorite, were analyzed for alkalis (K and Rb) and alkaline earths (Sr, Ba, Ca and Mg) by mass spectrometric isotope dilution. Most BO chondrules with higher alkalis (greater than the CI level) have nearly CI-<span class="hlt">chondritic</span> Rb/K ratios, while those with lower alkalis clearly show higher Rb/K ratios than the CI-<span class="hlt">chondritic</span>. In general, BO chondrules with higher Rb/K exhibit more depletion of alkalis relative to Ca. The mean olivine Fa for individual chondrules positively correlates with bulk alkali concentrations in BO type but not in porphyritic type chondrules. These observations suggest that some BO chondrules formed from more reducing assemblages of precursor minerals, which experienced more intensive vaporization losses of alkalis, accompanied by Rb/K fractionation, during the chondrule-formation melting. 30 refs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940007719&hterms=phosphorous&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dphosphorous','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940007719&hterms=phosphorous&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dphosphorous"><span id="translatedtitle">Anomalous REE patterns in unequilibrated enstatite <span class="hlt">chondrites</span>: Evidence and implications</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Crozaz, Ghislaine; Hsu, Weibiao</p> <p>1993-01-01</p> <p>We present here a study of Rare Earth Element (REE) microdistributions in unequilibrated enstatite <span class="hlt">chondrites</span> (EOC's). Although the whole rock REE contents are similar in both unequilibrated and equilibrated <span class="hlt">chondrites</span>, the host minerals of these refractory elements are different. In the least equilibrated ordinary <span class="hlt">chondrites</span> (UOC's), the REE reside mainly in glass whereas, in their more equilibrated counterparts, the bulk of the REE is in calcium phosphate, a metamorphic mineral that formed by oxidation of phosphorous originally contained in metal. In the smaller group of enstatite (E) <span class="hlt">chondrites</span>, calcium phosphate is absent and the phase that contains the highest REE concentrations is a minor mineral, CaS (oldhamite), which contains approximately 50 percent of the total Ca present. In E <span class="hlt">chondrites</span>, elements typically considered to be lithophiles (such as Ca and Mn) occur in sulfides rather than silicates. This indicates formation under extremely reducing conditions, thus in a region of the solar nebula distinct from those that supplied the more abundant ordinary and <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>. Previously, we observed a variety of REE patterns in the oldhamite of UEC's; they range from almost flat to some with pronounced positive Eu and Yb anomalies. Here, we searched for complementary REE patterns in other minerals from E <span class="hlt">chondrites</span> and found them in the major mineral, enstatite. Whenever Eu and Yb anomalies are present in this mineral, they are always negative.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14513703','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14513703"><span id="translatedtitle">[Biographical notes about Salvador <span class="hlt">Allende</span> G].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cruz-Coke, Ricardo</p> <p>2003-07-01</p> <p>Thirty years have elapsed since the tragic death of Salvador <span class="hlt">Allende</span>, MD. He occupies a high position as a symbol of the fall of real socialism. He became the most famous physician/politician of his times in Chile and the tracks of his life became imprinted, during the past century, in the pages of Revista Médica de Chile. This is a proper time to reconstruct his historical memory from a more reflexive perspective.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850007306&hterms=CI&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DCI','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850007306&hterms=CI&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DCI"><span id="translatedtitle">Evolutionary history of CI and CM <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kerridge, J. F.; Macdougall, J. D.</p> <p>1984-01-01</p> <p>It is now clear that several different processes have acted upon various components of <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>, and that at least some of those processes occurred very early in solar system history. Because these meteorites are breccias, petrographic relationships are seldom informative about the order in which those processes took place. Nonetheless, information about such an evolutionary sequence would be of potential value in defining the nature of the source region for these meteorites. Implantation of solar wind derived noble gases into CI magnetite apparently postdated the period of aqueous activity believed to be responsible for magnetite production. Carbonate crystallization roughly coincided with one or more episodes of impact driven brecciation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5094114','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5094114"><span id="translatedtitle">Samarium-146 in the early solar system: evidence from neodymium in the <span class="hlt">Allende</span> meteorite</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lugmair, G.W.; Shimamura, T.; Lewis, R.S.; Anders, E.</p> <p>1983-12-02</p> <p>A carbon-chromite fraction from the <span class="hlt">Allende</span> C3V <span class="hlt">chondrite</span> shows strikingly large isotopic enrichments of neodymium-142 (0.47%) and neodymium-143 (36%). Both apparently formed by ..cap alpha.. decay of samarium-146 and samarium-147 (half-lives 1.03 x 10/sup 8/ and 1.06 x 10/sup 11/ years), but the isotopic enrichment was greatly magnified by recoil of residual nuclei into a carbon film surrounding the samarium-bearing grains. These data provide an improved estimate of the original abundance of extinct samarium-146 in the early solar system (/sup 146/Sm//sup 144/Sm = (4.5 +/- 0.5) x 10/sup -3/), higher than predicted by some models of p-process nucleosynthesis. It may be possible to use this isotopic pair as a chronometer of the early solar system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17776245','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17776245"><span id="translatedtitle">Samarium-146 in the early solar system: evidence from neodymium in the <span class="hlt">allende</span> meteorite.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lugmair, G W; Shimamura, T; Lewis, R S; Anders, E</p> <p>1983-12-01</p> <p>A carbon-chromite fraction from the <span class="hlt">Allende</span> C3V <span class="hlt">chondrite</span> shows strikingly large isotopic enrichments of neodymium-142 (0.47 percent) and neodymium- 143 (36 percent). Both apparently formed by alpha decay of samarium-146 and samarium-147 (half-lives 1.03 x 10(8) and 1.06 x 10(11) years), but the isotopic enrichment was greatly magnified by recoil of residual nuclei into a carbon film surrounding the samarium-bearing grains. These data provide an improved estimate of the original abundance of extinct samarium-146 in the early solar system [(146)Sm/(144)Sm = (4.5 +/- 0.5) x 10(-3)], higher than predicted by some models of pprocess nucleosynthesis. It may be possible to use this isotopic pair as a chronometer of the early solar system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19840031130&hterms=Neodymium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DNeodymium','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19840031130&hterms=Neodymium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DNeodymium"><span id="translatedtitle">Samarium-146 in the early solar system - Evidence from neodymiun in the <span class="hlt">Allende</span> meteorite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lugmair, G. W.; Shimamura, T.; Lewis, R. S.; Anders, E.</p> <p>1983-01-01</p> <p>A carbon-chromite fraction from the <span class="hlt">Allende</span> C3V <span class="hlt">chondrite</span> shows strikingly large isotopic enrichments of neodymium-142 (0.47 percent) and neodymium-143 (36 percent). Both apparently formed by alpha decay of samarium-146 and samarium-147 (half-lives 1.03 x 10 to the 8th and 1.06 x 10 to the 11th years), but the isotopic enrichment was greatly magnified by recoil of residual nuclei into a carbon film surounding the samarium-bearing grains. These data provide an improved estimate of the original abundance of extinct samarium-146 in the early solar system, Sm-146/Sm-144 = (4.5 + or - 0.5) x 10 to the -3rd, higher than predicted by some models of p-process nucleosynthesis. It may be possible to use this isotopic pair as a chronometer of the early solar system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004IJMSp.232...83F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004IJMSp.232...83F"><span id="translatedtitle">Application of MC-ICPMS to the precise determination of tellurium isotope compositions in <span class="hlt">chondrites</span>, iron meteorites and sulfides</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fehr, Manuela A.; Rehkämper, Mark; Halliday, Alex N.</p> <p>2004-03-01</p> <p>New mass spectrometric techniques have been developed for the precise and accurate determination of Te isotope compositions. The methods are suitable for the analysis of stony and iron meteorites as well as sulfide mineral separates, such that they can be applied to search for Te isotope anomalies in various solar system materials. Tellurium is first separated from its matrix with a two-stage liquid chromatographic procedure. For iron meteorites, solvent-extraction is used to isolate Te from Fe prior to the column separation. The isotope composition of Te is then determined by multiple-collector inductively coupled plasma-mass spectrometry (MC-ICPMS). Tellurium has a very high first ionization potential and thus MC-ICPMS is much more suitable for the isotopic analyses than positive ion thermal ionization mass spectrometry (TIMS). Only about 100 ng Te are required for a single high precision measurement. Analyses of two terrestrial sulfides, the <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> <span class="hlt">Allende</span> and the iron meteorite Canyon Diablo reveal that these have Te isotope compositions that are identical to the terrestrial standard within uncertainty. The Te isotope data acquired for standard solutions as well as meteorites and sulfides display reproducibilities (2[sigma]) of approximately +/-4500 ppm for 120Te/128Te, +/-140 ppm for 122Te/128Te, +/-100 ppm for 124Te/128Te, +/-30 ppm for 126Te/128Te, and +/-60 ppm for 130Te/128Te. Compared to published results for meteorite samples obtained by TIMS, this represents an improvement in precision of about one to two orders of magnitude for 122-130Te/128Te and by a factor of 4 for 120Te/128Te. A number of experiments furthermore demonstrate that the isotope data acquired by MC-ICPMS are accurate, even for complex geological samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070011758','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070011758"><span id="translatedtitle">The Aqueous Alteration of CR <span class="hlt">Chondrites</span>: Experiments and Geochemical Modeling</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Perronnet, M.; Berger, G.; Zolensky, M. E.; Toplis, M. J.; Kolb, V. M.; Bajagic, M.</p> <p>2007-01-01</p> <p>CR <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> are of major interest since they contain some of the most primitive organic matter known. However, aqueous alteration has more or less overprinted their original features in a way that needs to be assessed. This study was initiated by comparing the mineralogy and modal abundances of the most altered CR1 <span class="hlt">chondrite</span>, GRO 95577, to a less altered CR2. Calculated element distributions imply that GRO 95577 may result from aqueous alteration of Renazzo by an isochemical process on their parent asteroid, whose mineralogical composition was estimated ( Unaltered CR shown included table).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70023885','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70023885"><span id="translatedtitle">Comparative 187Re-187Os systematics of <span class="hlt">chondrites</span>: Implications regarding early solar system processes</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Walker, R.J.; Horan, M.F.; Morgan, J.W.; Becker, H.; Grossman, J.N.; Rubin, A.E.</p> <p>2002-01-01</p> <p>A suite of 47 <span class="hlt">carbonaceous</span>, enstatite, and ordinary <span class="hlt">chondrites</span> are examined for Re-Os isotopic systematics. There are significant differences in the 187Re/188Os and 187Os/188Os ratios of <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> compared with ordinary and enstatite <span class="hlt">chondrites</span>. The average 187Re/188Os for <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> is 0.392 ?? 0.015 (excluding the CK <span class="hlt">chondrite</span>, Karoonda), compared with 0.422 ?? 0.025 and 0.421 ?? 0.013 for ordinary and enstatite <span class="hlt">chondrites</span> (1?? standard deviations). These ratios, recast into elemental Re/Os ratios, are as follows: 0.0814 ?? 0.0031, 0.0876 ?? 0.0052 and 0.0874 ?? 0.0027 respectively. Correspondingly, the 187Os/188Os ratios of <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> average 0.1262 ?? 0.0006 (excluding Karoonda), and ordinary and enstatite <span class="hlt">chondrites</span> average 0.1283 ?? 0.0017 and 0.1281 ?? 0.0004, respectively (1?? standard deviations). The new results indicate that the Re/Os ratios of meteorites within each group are, in general, quite uniform. The minimal overlap between the isotopic compositions of ordinary and enstatite <span class="hlt">chondrites</span> vs. <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> indicates long-term differences in Re/Os for these materials, most likely reflecting chemical fractionation early in solar system history. A majority of the <span class="hlt">chondrites</span> do not plot within analytical uncertainties of a 4.56-Ga reference isochron. Most of the deviations from the isochron are consistent with minor, relatively recent redistribution of Re and/or Os on a scale of millimeters to centimeters. Some instances of the redistribution may be attributed to terrestrial weathering; others are most likely the result of aqueous alteration or shock events on the parent body within the past 2 Ga. The 187Os/188Os ratio of Earth's primitive upper mantle has been estimated to be 0.1296 ?? 8. If this composition was set via addition of a late veneer of planetesimals after core formation, the composition suggests the veneer was dominated by materials that had Re/Os ratios most similar to ordinary and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150001624','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150001624"><span id="translatedtitle">Evidence for Impact Shock Melting in CM and CI <span class="hlt">Chondrite</span> Regolith Samples</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zolensky, Michael; Mikouchi, Takashi; Hagiya, Kenji; Ohsumi, Kazumasa; Komatsu, Mutsumi; Le, Loan</p> <p>2014-01-01</p> <p>C class asteroids frequently exhibit reflectance spectra consistent with thermally metamorphosed <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>, or a mixture of phyllosilicate-rich material along with regions where they are absent. One particularly important example appears to be near-Earth asteroid 1999 JU3, the target of the Hayabusa II sample return mission [1], although not all spectra indicate this. In fact most spectra of 1999 JU3 are featureless, suggesting a heterogeneous regolith. Here we explore an alternative cause of dehydration of regolith of C class asteroids - impact shock melting. Impact shock melting has been proposed to explain some mineralogical characteristics of CB <span class="hlt">chondrites</span>, but has not been considered a major process for hydrous <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>. What evidence is there for significant shock melting in the very abundant CMs, or less abundant but still important CI <span class="hlt">chondrites</span>?</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016M%26PS...51..851J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016M%26PS...51..851J"><span id="translatedtitle">Northwest Africa 5958: A weakly altered CM-related ungrouped <span class="hlt">chondrite</span>, not a CI3</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jacquet, Emmanuel; Barrat, Jean-Alix; Beck, Pierre; Caste, Florent; Gattacceca, JéRôMe; Sonzogni, Corinne; Gounelle, Matthieu</p> <p>2016-05-01</p> <p>Northwest Africa (NWA) 5958 is a <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> found in Morocco in 2009. Preliminary chemical and isotopic data leading to its initial classification as C3.0 ungrouped have prompted us to conduct a multitechnique study of this meteorite and present a general description here. The petrography and chemistry of NWA 5958 is most similar to a CM <span class="hlt">chondrite</span>, with a low degree of aqueous alteration, apparently under oxidizing conditions, and evidence of a second, limited alteration episode manifested by alteration fronts. The oxygen isotopic composition, with ∆'17O = -4.3‰, is more 16O-rich than all CM <span class="hlt">chondrites</span>, indicating, along with other compositional arguments, a separate parent body of origin. We suggest that NWA 5958 be reclassified as an ungrouped <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> related to the CM group.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19820048211&hterms=sem&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dsem','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820048211&hterms=sem&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dsem"><span id="translatedtitle">SEM, optical, and Moessbauer studies of submicrometer chromite in <span class="hlt">Allende</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Housley, R. M.</p> <p>1982-01-01</p> <p>New scanning electron and optical microscope results are presented showing that sub-micrometer chromite is abundant along healed cracks and grain boundaries in <span class="hlt">Allende</span> chondrule olivine. Some wider healed cracks also contain pentlandite and euhedral Ni3Fe grains. Also reported are Moessbauer measurements on <span class="hlt">Allende</span> HF-HCl residues confirming a high Fe(+++)/Fe(++) ratio.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005ASPC..341..953W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ASPC..341..953W"><span id="translatedtitle">The <span class="hlt">Chondrite</span> Types and Their Origins</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wood, J. A.</p> <p>2005-12-01</p> <p>Recent advances in the dating of ferromagnesian chondrules are summarized, and the conclusion seems unavoidable (the author's earlier convictions notwithstanding) that chondrules comprising a given <span class="hlt">chondrite</span> are the product of nebular activity extending over a million years or more. Continuing chondrule-forming activity, probably successive shock events, can explain the non-solar major element chemical compositions of the ordinary <span class="hlt">chondrites</span> (OC): they are the cumulative effect of repeated small changes in the local system composition that accompanied each chondrule- forming event. In particular Fe,Ni metal was increasingly lost from the system with time, presumably by incorporation in planetesimals (most of them unsampled) at the nebular midplane. Fe/Si in the system progressed smoothly with time through values appropriate to the H, L, and LL OC groups. The parent bodies of each of these groups were accreted in a relatively short time, during which Fe/Si was essentially constant, then accretion effectively ceased, probably because the parent body was perturbed into an inclined orbit and no longer spent much time in the chondrule-rich nebular midplane. The perturbations are probably ascribable to the same density waves (gravitational irregularities) that created chondrule-forming shocks. Implementation of this concept is also explored for <span class="hlt">carbonaceous</span> and enstatite <span class="hlt">chondrites</span>. Maintenance of the differences in composition of the various <span class="hlt">chondrite</span> types, which formed at differing radial distances, requires that turbulent diffusion was not effective in the zone of <span class="hlt">chondrite</span> formation. Instead periodic disturbances by the nebular density waves were probably responsible for remixing solids from the midplane zone into the body of the nebula.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900007313','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900007313"><span id="translatedtitle">Identification of solar nebula condensates in interplanetary dust particles and unequilibrated ordinary <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kloeck, W.; Thomas, K. L.; Mckay, D. S.</p> <p>1989-01-01</p> <p>Orthopyroxene and olivine grains, low in FeO, but containing MnO contents up to 5 wt percent were found in interplanetary dust particles (IDP) collected in the stratosphere. The majority of olivines and pyroxenes in meteorites contain less than 0.5 wt percent MnO. Orthopyroxenes and olivines high in Mn and low in FeO have only been reported from a single coarse grained chondrule rim in the <span class="hlt">Allende</span> meteorite and from a Tieschitz matrix augite grain. The bulk MnO contents of the extraterrestrial dust particles with high MnO olivines and pyroxenes are close to CI <span class="hlt">chondrite</span> abundances. High MnO, low FeO olivines and orthopyroxenes were also found in the matrix of Semarkona, an unequilibrated ordinary <span class="hlt">chondrite</span>. This may indicate a related origin for minerals in extraterrestrial dust particles and in the matrix of unequilibrated ordinary <span class="hlt">chondrites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988Metic..23..378M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988Metic..23..378M"><span id="translatedtitle">The Linum <span class="hlt">chondrite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matthes, J.; Adam, K.</p> <p>1988-12-01</p> <p>Based on optical microscopy and electron microprobe analysis, the Linum (East Germany) <span class="hlt">chondrite</span> is classified as an L6b <span class="hlt">chondrite</span> that contains olivine (Fa24), orthopyroxene (Fs20), clinopyroxene (Wo45En47Fs8), plagioclase (An10Ab84Or6), nickel-iron, troilite, chromite and accessory amounts of chlorapatite and whitlockite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110005555','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110005555"><span id="translatedtitle">High Precision Oxygen Three Isotope Analysis of Wild-2 Particles and Anhydrous <span class="hlt">Chondritic</span> Interplanetary Dust Particles</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nakashima, D.; Ushikubo, T.; Zolensky, Michael E.; Weisberg, M. K.; Joswiak, D. J.; Brownlee, D. E.; Matrajt, G.; Kita, N. T.</p> <p>2011-01-01</p> <p>One of the most important discoveries from comet Wild-2 samples was observation of crystalline silicate particles that resemble chondrules and CAIs in <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>. Previous oxygen isotope analyses of crystalline silicate terminal particles showed heterogeneous oxygen isotope ratios with delta(sup 18)O to approx. delta(sup 17)O down to -50% in the CAI-like particle Inti, a relict olivine grain in Gozen-sama, and an olivine particle. However, many Wild-2 particles as well as ferromagnesian silicates in anhydrous interplanetary dust particles (IDPs) showed Delta(sup 17)O values that cluster around -2%. In <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>, chondrules seem to show two major isotope reservoirs with Delta(sup 17)O values at -5% and -2%. It was suggested that the Delta(sup 17)O = -2% is the common oxygen isotope reservoir for <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> chondrules and cometary dust, from the outer asteroid belt to the Kuiper belt region. However, a larger dataset with high precision isotope analyses (+/-1-2%) is still needed to resolve the similarities or distinctions among Wild-2 particles, IDPs and chondrules in meteorites. We have made signifi-cant efforts to establish routine analyses of small particles (< or =10micronsm) at 1-2% precision using IMS-1280 at WiscSIMS laboratory. Here we report new results of high precision oxygen isotope analyses of Wild-2 particles and anhydrous <span class="hlt">chondritic</span> IDPs, and discuss the relationship between the cometary dust and <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> chondrules.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19870029377&hterms=chromium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dchromium','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870029377&hterms=chromium&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dchromium"><span id="translatedtitle">Chromium isotopic anomalies in the <span class="hlt">Allende</span> meteorite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Papanastassiou, D. A.</p> <p>1986-01-01</p> <p>Abundances of the chromium isotopes in terrestrial and bulk meteorite samples are identical to 0.01 percent. However, Ca-Al-rich inclusions from the <span class="hlt">Allende</span> meteorite show endemic isotopic anomalies in chromium which require at least three nucleosynthetic components. Large anomalies at Cr-54 in a special class of inclusions are correlated with large anomalies at Ca-48 and Ti-50 and provide strong support for a component reflecting neutron-rich nucleosynthesis at nuclear statistical equilibrium. This correlation suggests that materials from very near the core of an exploding massive star may be injected into the interstellar medium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19900060763&hterms=zinc&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dzinc','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19900060763&hterms=zinc&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dzinc"><span id="translatedtitle">Zinc isotope anomalies in <span class="hlt">Allende</span> meteorite inclusions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Loss, R. D.; Lugmair, G. W.</p> <p>1990-01-01</p> <p>The isotopic compositions of Zn, Cr, Ti, and Ca have been measured in a number of CAIs from the <span class="hlt">Allende</span> meteorite. The aim was to test astrophysical models which predict large excesses of Zn-66 to accompany excesses in the neutron-rich isotopes of Ca, Ti, Cr, and Ni. Some of the CAIs show clearly resolved but small excesses for Zn-66 which are at least an order of magnitude smaller than predicted. This result may simply reflect the volatility and chemical behavior of Zn as compared to the other (more refractory) anomalous elements found in these samples. Alternatively, revision of parameters and assumptions used for the model calculations may be required.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6966460','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6966460"><span id="translatedtitle">Iron isotope anomalies. [In <span class="hlt">carbonaceous</span> meteorites</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Voelkening, J.; Papanastassiou, D.A. )</p> <p>1989-12-01</p> <p>Precise determinations of the Fe isotope abundances yield identical results for a terrestrial standard and for samples of <span class="hlt">carbonaceous</span> meteorites. Fe-54/Fe-56 = 0.062669; Fe-57/Fe-56 = 0.023261 + or - 0.000002; and Fe-58/Fe-56 = 0.0031132 + or - 0.0000011 are found. Refractory element-rich inclusions from the <span class="hlt">Allende</span> <span class="hlt">carbonaceous</span> meteorite yield hints of deficits in Fe-57/Fe-56 of up to -3.9 + or - 2.6 parts in 10,000 and a hint of excess in Fe-58/Fe-56 of up to 27 + or - 11 parts in 10,000. One special (FUN) inclusion shows a large excess of 2.9 percent, uniquely attributable to Fe-58. This excess correlates with large excesses in the same inclusion in the neutron-rich isotopes Ca-48, Ti-50 and Cr-54. These results strengthen the evidence for an exotic nucleosynthetic component produced by neutron-rich, statistical equilibrium burning, and injected into the interstellar medium. 29 refs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940011813','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940011813"><span id="translatedtitle">Partial melting of ordinary <span class="hlt">chondrites</span>: Lost City (H) and St. Severin (LL)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jurewicz, Amy J. G.; Jones, John H.; Weber, Egon T.; Mittlefehldt, David W.</p> <p>1993-01-01</p> <p>Eucrites and diogenites are examples of asteroidal basalts and orthopyroxenites, respectively. As they are found intermingled in howardites, which are inferred to be regolith breccias, eucrites and diogenites are thought to be genetically related. But the details of this relationship and of their individual origins remain controversial. Work by Jurewicz et al. showed that 1170-1180 C partial melts of the (anhydrous) Murchison (CM) <span class="hlt">chondrite</span> have major element compositions extremely similar to primitive eucrites, such as Sioux County. However, the MnO contents of these melts were about half that of Sioux County, a problem for the simple partial melting model. In addition, partial melting of Murchison could not produce diogenites, because residual pyroxenes in the Murchison experiments were too Fe- and Ca-rich and were minor phases at all but the lowest temperatures. A parent magma for diogenites needs an expanded low-calcium pyroxene field. In their partial melting study of an L6 <span class="hlt">chondrite</span>, Kushiro and Mysen found that ordinary <span class="hlt">chondrites</span> did have an expanded low-Ca pyroxene field over that of CV <span class="hlt">chondrites</span> (i.e., <span class="hlt">Allende</span>), probably because ordinary <span class="hlt">chondrites</span> have lower Mg/Si ratios. This study expands that of both Kushiro and Mysen and Jurewicz et al. to the Lost City (H) and St. Severin (LL) <span class="hlt">chondrites</span> at temperatures ranging from 1170 to 1325 C, at an fO2 of one log unit below the iron-wuestite buffer (IW-1).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910058645&hterms=phosphate&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dphosphate','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910058645&hterms=phosphate&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dphosphate"><span id="translatedtitle"><span class="hlt">Chondrite</span> chronology by initial Sr-87/Sr-86 in phosphates?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Podosek, Frank A.; Brannon, Joyce C.</p> <p>1991-01-01</p> <p>New data are presented on Rb-Sr isotope analyses of phosphates from nine ordinary <span class="hlt">chondrites</span>, including accurate identification of initial Sr-87/Sr-86. The initial Sr-87/Sr-86 ratios found in this study were generally significantly higher than the more primitive initial Sr-87/Sr-86 ratios inferred for <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> refractory inclusions, basaltic achondrites, or bulk ordinary <span class="hlt">chondrites</span>. Such elevation of initial Sr-87/Sr-86 is generally considered to reflect isotopic redistribution during metamorphism. However, in this study, no evident correlation was found between the phosphate initial Sr-87/Sr-86 compositions and the metamorphic grade. Two possible alternative hypotheses for high initial Sr-87/Sr-86 ratios are considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1980GeCoA..44..253M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1980GeCoA..44..253M"><span id="translatedtitle">Noble-gas-rich separates from ordinary <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moniot, R. K.</p> <p>1980-02-01</p> <p>Acid-resistant residues were prepared by HCl-HF demineralization of three H-type ordinary <span class="hlt">chondrites</span>: Brownfield 1937 (H3), Dimmitt (H3, 4), and Estacado (H6). These residues were found to contain a large proportion of the planetary-type trapped Ar, Kr, and Xe in the meteorites. The similarity of these acid residues to those from <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> and LL-type ordinary <span class="hlt">chondrites</span> suggests that the same phase carries the trapped noble gases in all these diverse meteorite types. Because the H group represents a large fraction of all meteorites, this result indicates that the gas-rich carrier phase is as universal as the trapped noble-gas component itself. When treated with an oxidizing etchant, the acid residues lost almost all their complement of noble gases.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160002648','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160002648"><span id="translatedtitle">40Ar/39Ar Ages of <span class="hlt">Carbonaceous</span> Xenoliths in 2 HED Meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Turrin, B.; Lindsay, F. N.; Park, J.; Herzog, G. F.; Delaney, J. S.; Swisher, C. C., III; Johnson, J.; Zolensky, M.</p> <p>2016-01-01</p> <p>The generally young K/Ar and 40Ar/39Ar ages of CM <span class="hlt">chondrites</span> made us wonder whether <span class="hlt">carbonaceous</span> xenoliths (CMX) entombed in Howardite–Eucrite–Diogenite (HED) meteorites might retain more radiogenic 40Ar than do ‘free-range’ CM-<span class="hlt">chondrites</span>. To find out, we selected two HED breccias with <span class="hlt">carbonaceous</span> inclusions in order to compare the 40Ar/39Ar release patterns and ages of the inclusions with those of nearby HED material. <span class="hlt">Carbonaceous</span> inclusions (CMXs) in two HED meteorites lost a greater fraction of radiogenic 40Ar than did surrounding host material, but a smaller fraction of it than did free-range CM-<span class="hlt">chondrites</span> such as Murchison or more heavily altered ones. Importantly, however, the siting of the CMXs in HED matrix did not prevent the 40Ar loss of about 40 percent of the radiogenic 40Ar, even from phases that degas at high laboratory temperatures. We infer that <span class="hlt">carbonaceous</span> asteroids with perihelia of 1 astronomical unit probably experience losses of at least this size. The usefulness of 40Ar/39Ar dating for samples returned from C-type asteroids may hinge, therefore, on identifying and analyzing separately small quantities of the most retentive phases of <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19720054194&hterms=malls&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dmalls','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19720054194&hterms=malls&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dmalls"><span id="translatedtitle">The Seoni <span class="hlt">chondrite</span>.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bunch, T. E.; Mall, A. P.; Lewis, C. F.</p> <p>1972-01-01</p> <p>Description of the Seoni (India, 1966) <span class="hlt">chondrite</span> in terms of its mineralogy, bulk chemistry, and sample shape and mass. It is an H6 group ordinary <span class="hlt">chondrite</span> that contains olivine, orthopyroxene, clinopyroxene, plagioclase, together with chromite, troilite, kamacite, taenite, chlorapatite, and whitlockite. Recrystallization has been quite extensive, as indicated by the presence of a few remnant chondrules, low abundance of clinopyroxene, and relatively high abundance of well formed plagioclase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995Metic..30S.562P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995Metic..30S.562P"><span id="translatedtitle">54-Cr Anomalies in the Orgueil <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Podosek, F. A.; Ott, U.; Brannon, J. C.; Bernatowicz, T. J.; Neal, C. R.</p> <p>1995-09-01</p> <p>Cr in CI meteorites displays isotopic anomalies in a unique pattern [1-3]. Etching of bulk Orgueil in relatively mild reactants (CH3COOH and dilute HNO3) dissolves most (>80%) of the Cr along with most of other major cations (Mg, Ca, Fe, Ni, Al). The Cr thus dissolved is deficient in 54Cr by about 6 epsilon-units (using 50Cr/52Cr normalization). Much of the remaining Cr is released in further etching in HCl; this Cr has stronger excesses of 54Cr, up to around 100epsilon. Dissolution of the residues in more aggressive reactants yields Cr with smaller excesses of 54Cr. There are no known correlating anomalies in other elements or even in 53Cr. Although no Cr carrier in Orgueil has isotopically normal Cr, mass balance calculations indicate approximately normal Cr in the whole rock. We have previously suggested that these results could be most simply explained by postulating one carrier phase, relatively rich in Cr and bearing strong excess 54Cr, presumably from neutron-rich nuclear statistical equilibrium nucleosynthesis. This phase would have to be soluble in HCl but resistant to parent body aqueous alteration. In this interpretation the 54Cr-deficiency in most of the Cr is understandable in terms of mixing of all the nucleosnthetic sources contributing to solar normal except for that in the postulated carrier phase. Qualitatively similar but more subdued isotopic effects occur in CM meteorites and are very subdued or absent in CV and CO meteorites[1]. If the parent bodies for these classes originally contained the same postulated phase in comparable abundance, the implication is that the 54Cr-enriched carrier phase is also not resistant to the thermal processing experienced by these classes. Interstellar grains bearing Cr from specific nucleosynthetic events would be expected to be much more anomalous than any samples yet observed; we thus lack evidence to determine whether the carrier is itself a type of interstellar grain (in which case all observations to date reflect major dilution with more nearly normal Cr) or whether it is a solar nebula product preferentially incorporating such interstellar grains. In either case, the implicated interstellar grain type is clearly different from the types already known and isolated (diamond, graphite, carbides, oxides), all of which are chemically and thermally resistant to nebular processing. We have examined fractions of Orgueil separated from a CH3COOH/HNO3 residue by a teflon-coated magnetic stirring bar. For both fractions HCl treatment yields Cr more strongly enriched in 54Cr (by about 200epsilon) than any previously observed. Evidently this procedure is ineffective in separating the carrier (or there is more than one carrier); the magnetite which comprises most of the magnetic fraction is apparently just a dilutant. SEM/EDX analysis of the various etch residues (and untreated bulk) for Orgueil reveals the presence of small (mostly submicron) Cr-rich grains (Cr and O, often with significant Fe and/or Mn). Quantitative abundance determination of such grains is difficult, nor can we be confident about their disappearance or persistence in HCl etching, but such grains could account for the observed isotopic effects if they are very enriched in 54Cr. Preliminary ion probe measurements on the non-magnetic fraction of Orgueil indicate that most Cr-rich spots have normal Cr within errors but that some have large 54Cr enrichments (at least tens of percent). One such grain may have a truly radical Cr isotopic composition. References: [1] Rotaru M. et al. (1992) Nature, 358, 465-470. [2] Ott U. et al. (1994) LPSC XXV, 1033-1034. [3] Podosek F. A. et al. (1994) Meteoritics, 29, 519.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980209648','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980209648"><span id="translatedtitle">Shock Modifications of Organic Compounds in <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrite</span> Parent Bodies</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cooper, George W.</p> <p>1998-01-01</p> <p>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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120017947','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120017947"><span id="translatedtitle">The Amino Acid Composition of the Sutter's Mill <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Glavin, D. P.; Burton, A. S.; Elsila, J. E.; Dworkin, J. P.; Yin, Q. Z.; Cooper, G.; Jenniskens, P.</p> <p>2012-01-01</p> <p>In contrast to the Murchison meteorite which had a complex distribution of amino acids with a total C2 to Cs amino acid abundance of approx.14,000 parts-per-billion (ppb) [2], the Sutters Mill meteorite was found to be highly depleted in amino acids. Much lower abundances (approx.30 to 180 ppb) of glycine, beta-alanine, L-alanine and L-serine were detected in SM2 above procedural blank levels indicating that this meteorite sample experienced only minimal terrestrial amino acid contamination after its fall to Earth. Carbon isotope measurements will be necessary to establish the origin of glycine and beta-alanine in SM2. Other non-protein amino acids that are rare on Earth, yet commonly found in other CM meteorites such as aaminoisobutyric acid (alpha-AIB) and isovaline, were not identified in SM2. However, traces of beta-AIB (approx.1 ppb) were detected in SM2 and could be" extraterrestrial in origin. The low abundances of amino acids in the Sutter's Mill meteorite is consistent with mineralogical evidence that at least some parts of the Sutter's Mill meteorite parent body experienced extensive aqueous and/or thermal alteration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016LPICo1921.6153G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016LPICo1921.6153G"><span id="translatedtitle">Organic Globules in <span class="hlt">Carbonaceous</span> <span class="hlt">Chondrites</span>: An Experimental Approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Giese, C.-C.; ten Kate, I. L.; Plümper, O.; King, H. E.; Geisler, T.; Lenting, C.; Tielens, X.</p> <p>2016-08-01</p> <p>PAHs have been considered as material composing organic globules in CCs. In order to test the PAH precursor hypothesis, we conducted hydrothermal as well as melting experiments with two different types of PAHs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70010050','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70010050"><span id="translatedtitle">Atmospheric collection of debris from the Revelstoke and <span class="hlt">Allende</span> fireballs</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Carr, M.H.</p> <p>1970-01-01</p> <p>In two separate events, Revelstoke and <span class="hlt">Allende</span>, the air through which a fireball had been observed to pass was sampled for meteoritic debris. Particulate matter was collected on fibrous filters, which were mounted on aircraft and flown downwind from the site of the meteorite fall at altitudes of 10,000-12,000 m. From Revelstoke, a highly distinctive assemblage of particles was collected. Included were large numbers of magnetite spherules, transparent siliceous spherules, and several types of irregular nickel-bearing particles. The <span class="hlt">Allende</span> collections yielded only slightly more magnetite and siliceous spherules than background and no nickel-bearing particles. Revelstoke and <span class="hlt">Allende</span> are believed to be representative of two different types of events. In the Revelstoke type, large amounts of meteoritic debris are left in the atmosphere and little reaches the ground in large coherent fragments; in the <span class="hlt">Allende</span> type, little material remains in the atmosphere but large fragments reach the ground in the fall area. ?? 1970.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20020046328&hterms=inclusion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dinclusion','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20020046328&hterms=inclusion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dinclusion"><span id="translatedtitle">Cr Isotopes in <span class="hlt">Allende</span> Ca-Al-rich Inclusions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bogdanovski, O.; Papanastassiou, D. A.; Wasserburg, G. J.</p> <p>2002-01-01</p> <p>We have determined Cr isotope compositions in minerals from <span class="hlt">Allende</span> CAI in order to address the initial 53Mn (half-life 3.7 Ma) abundance in the solar system. Additional information is contained in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19940007660&hterms=CI&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DCI','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19940007660&hterms=CI&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DCI"><span id="translatedtitle">Volatiles in fourteen interplanetary dust particles: A comparison with CI and CM <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bustin, R.; Gibson, E. K., Jr.; Wentworth, S. J.</p> <p>1993-01-01</p> <p>In an attempt to classify the nature of volatiles within interplanetary dust particles (IDP's), 14 IDP's using a laser microprobe/mass spectrometer (LM/MS) technique were studied. Volatile abundances and distributions found for the IDP's are compared with those measured for <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> in order to determine if the IDP's are related to the parent bodies of these primitive meteorites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120015696','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120015696"><span id="translatedtitle">Inconclusive Evidence for Non-Terrestrial Isoleucine Enantiomeric Excesses in CR <span class="hlt">Chondrites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Elsila, Jamie E.; Glavin, Daniel P.; Dworkin, Jason P.; Martins, Zita; Bada, Jeffrey L.</p> <p>2012-01-01</p> <p>Researchers recently described the soluble organic content of eight Antarctic CR <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> and reported large enantiomeric excesses (ee) of L-isoleucine and Dalloisoleucine. The reported ee values decrease with inferred increases in aqueous alteration. We believe the conclusions presented in the manuscript are not fully justified and the data are potentially flawed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6479468','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6479468"><span id="translatedtitle">Zinc isotope anomalies in <span class="hlt">Allende</span> meteorite inclusions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Loss, R.D.; Lugmair, G.W. )</p> <p>1990-09-01</p> <p>The isotopic compositions of Zn, Cr, Ti, and Ca have been measured in a number of CAIs from the <span class="hlt">Allende</span> meteorite. The aim was to test astrophysical models which predict large excesses of Zn-66 to accompany excesses in the neutron-rich isotopes of Ca, Ti, Cr, and Ni. Some of the CAIs show clearly resolved but small excesses for Zn-66 which are at least an order of magnitude smaller than predicted. This result may simply reflect the volatility and chemical behavior of Zn as compared to the other (more refractory) anomalous elements found in these samples. Alternatively, revision of parameters and assumptions used for the model calculations may be required. 34 refs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19780057660&hterms=Krypton&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DKrypton','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19780057660&hterms=Krypton&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DKrypton"><span id="translatedtitle">Anomalous krypton in the <span class="hlt">Allende</span> meteorite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Frick, U.</p> <p>1977-01-01</p> <p>The reported investigation provides important new data for the heavy noble gases, especially Kr, in the <span class="hlt">Allende</span> meteorite. The data are used to criticize the original model of Lewis et al. (1975) based on the noble gas data of these researchers. The conclusions reached in the investigation support alternative models which have been mainly based on Xe data by Lewis et al. (1975, 1977). Because of the relatively high noble gas abundances in the separates studied, disturbance from nuclear effects occurring in situ such as spallation and neutron capture is insignificant, offering an opportunity to study primordial Ar, Kr, and Xe. The isotopic and abundance data obtained from the samples largely confirm the noble gas results of Lewis et al. (1975, 1977) where isotopic correlations agree with the correlations of the considered samples. It is found that both Kr and Xe data are consistent with a two component mixture of 'ordinary' as well as 'anomalous' planetary gases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19820048221&hterms=density+egg&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Ddensity%2Begg','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820048221&hterms=density+egg&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Ddensity%2Begg"><span id="translatedtitle">Silicon and oxygen isotopes in selected <span class="hlt">Allende</span> inclusions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Becker, R. H.; Epstein, S.</p> <p>1982-01-01</p> <p>Silicon and oxygen data are presented for a number of <span class="hlt">Allende</span> samples. It is found that based on oxygen and silicon isotopes, <span class="hlt">Allende</span> samples EGG-1, EGG-6, BG1a, and 3529Yc are typical, unfractionated <span class="hlt">Allende</span> inclusions. Where magnesium data are available, they indicate the same thing. EGG-3 is fractionated in both oxygen and silicon, as it is in magnesium. Sample D7 melilite is fractionated in oxygen by several per mil along the C2-matrix line, away from typical <span class="hlt">Allende</span> melilites. Inclusion BG10a is a FUN inclusion with an inferred original oxygen isotopic fractionation of 8-9 per mille/amu relative to the <span class="hlt">Allende</span> line. Silicon data for two density fractions of inclusion 3A with different mineralogies show a difference of about 2 per mille, which indicates that silicon, like oxygen, has been added to at least some mineral phases in <span class="hlt">Allende</span> inclusions from a reservoir other than the one in which the inclusion first began to form.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19900018265&hterms=graphite+diamond&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dgraphite%2Bdiamond','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19900018265&hterms=graphite+diamond&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dgraphite%2Bdiamond"><span id="translatedtitle">Nature and origin of interstellar diamond from the <span class="hlt">Allende</span> CV3 meteorite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Blake, David; Freund, Friedemann; Bunch, Ted; Krishnan, Kannan; Stampfer, Mitch; Chang, Sherwood; Tielens, Alexander G. G. M.</p> <p>1990-01-01</p> <p>Data and experimental evidence which support the contention that the C delta diamonds may result from grain-grain collisions in supernova shocks in the interstellar medium are presented. Fragments of the <span class="hlt">Allende</span> CV3 <span class="hlt">chondrite</span> were acid-treated. A whitish powder was obtained. For the Analytical Electron Microscopy (AEM) a small drop of ethanol suspension was transferred onto holey carbon support films on 3 mm EM grids. The AEM was performed on transmission-thin fragments of the material which overlay holes in the film, to eliminate interference from the substrate. Electron Spectroscopy for Chemical Analysis (ESCA) was performed on a large aliquot of C. Diamond was identified by selected area electron diffraction. Scanning Transmission Electron Microscope / Energy Dispersive X-ray (STEM-EDS) microanalyses of the C delta diamond, using a light-element detector, show that oxygen and possibly nitrogen are the only impurities consistently present. ESCA spectra from bulk C delta material confirm the presence of N at a level of 0.35 percent or less. Under UV irradiation a yellow-red fluorescence is observed, consistent with that of natural diamonds containing substitutional N. Electron Energy Loss Spectra (EELS) were recorded at 2 eV resolution from the C delta diamond, high pressure synthetic diamond, a diamond film produced in a low pressure plasma by chemical vapor deposition (CVD) on a heated silicon substrate (Roy, 1987), graphite, and amorphous arc sputtered carbon. Comparison of the carbon K edge shape and fine structure shows the <span class="hlt">Allende</span> C delta phase to be largely diamond, but with a significant pre-edge absorption feature indicative of transitions of C 1s electrons into pi asterisk orbitals which are absent in the purely sp(3)-bonded diamond but present in graphite and amorphous carbon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998M%26PS...33.1087W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998M%26PS...33.1087W"><span id="translatedtitle">Fayalitic olivine in CV3 <span class="hlt">chondrite</span> matrix and dark inclusions: A nebular origin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weisberg, Michael K.; Prinz, Martin</p> <p>1998-09-01</p> <p>Fayalitic olivine (Fa>32) is the major component of the matrices and Dark Inclusions (DI) of CV3 and other unequilibrated <span class="hlt">chondrites</span>. It occurs most commonly as rims, veins and halos in and around chondrule silicates in the <span class="hlt">Allende</span>-type (CV3OxA) <span class="hlt">chondrites</span> and to a much lesser extent in the reduced (CV3R) and Bali-type (CV3OxB) <span class="hlt">chondrites</span>. The olivines have distinctive platy, tabular and lath- or irregular-shaped crystals, with the ratio the two types varying widely. In CV3OxB <span class="hlt">chondrites</span>, matrix fayalitic olivines range up to Fa99.9, whereas in the other CV3 <span class="hlt">chondrites</span> the range is much smaller. The platy and tabular anisotropic forms of the fayalitic olivines strongly suggest growth from a vapor and the nature of occurrences suggests that CV3 matrices are unequilibrated mixtures of nebular materials. We argue that the parent body hydration/dehydration model has numerous inconsistencies that make this hypothesis highly unlikely. These include: (1) There is no direct evidence linking fayalitic olivine to precursor phyllosilicates. (2) Dehydration of phyllosilicates cannot explain the wide range of morphologies of the fayalitic olivines. (3) Fayalitic olivine clearly predates the formation of the hydrous phases in CV3 <span class="hlt">chondrites</span> and is one of the phases that breaks down to form phyllosilicates (Keller et al., 1994). (4) The unequilibrated nature of the matrix, including fine scale zoning in 10=B5-sized fayalitic olivine crystals, would not survive the parent body metamorphism required in the dehydration model. (5) A DI in the Ningqiang <span class="hlt">chondrite</span> contains fayalitic olivine rimmed by glassy and microcrystalline material (Zolensky et al., 1997), which probably formed by radiation damage. This indicates that the fayalitic olivine was exposed to solar radiation in a nebular setting. (6) Some <span class="hlt">Allende</span> chondrules contain unaltered primary, anhydrous glassy mesostasis in contact with the host matrix (e.g., Ikeda and Kimura, 1995). Chondrule mesostases would not have survived</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930069283&hterms=CI&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DCI','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930069283&hterms=CI&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DCI"><span id="translatedtitle">Carbonate compositions in CM and CI <span class="hlt">chondrites</span>, and implications for aqueous alteration</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Johnson, Craig A.; Prinz, Martin</p> <p>1993-01-01</p> <p>Carbonate minerals in fourteen CM <span class="hlt">chondrites</span> and two CI <span class="hlt">chondrites</span> have been analyzed by electron microprobe to provide a better understanding of the aqueous processes that affected <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> parent bodies. Calcites in CM <span class="hlt">chondrites</span> and dolomites and magnesites in CI <span class="hlt">chondrites</span> display the compositions expected of stable phases formed at low temperatures. Dolomites in CM <span class="hlt">chondrites</span>, identified here for the first time in five members of the group, have small amounts of excess Ca which may reflect metastable growth. The distribution of Fe between dolomite and coexisting serpentine differs in the two <span class="hlt">chondrite</span> groups. If the distributions reflect an approach to chemical equilibrium, then the difference implies higher alteration temperatures for the CI group than the CM group in agreement with the results of previously published oxygen isotope thermometry and mineral solubility modeling of the alteration process. Dolomite Fe contents are relatively uniform in the two <span class="hlt">chondrite</span> groups. Dolomite Mn contents, by contrast, vary widely. The variations may reflect transport-controlled coprecipitation of Mn resulting from a heterogeneous distribution of the element in the anhydrous precursor material. If this interpretation is correct, then the altering fluids were essentially immobile white hydration reactions proceeded on the meteorite parent bodies. The near closed-system character of the alteration process, long known from bulk chemical analyses of the meteorites, is a direct consequence of the limited mobility of dissolved species.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9836631','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9836631"><span id="translatedtitle">53Mn-53Cr dating of fayalite formation in the CV3 <span class="hlt">chondrite</span> Mokoia: evidence for asteroidal alteration.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hutcheon, I D; Krot, A N; Keil, K; Phinney, D L; Scott, E R</p> <p>1998-12-01</p> <p>Fayalite grains in chondrules in the oxidized, aqueously altered CV3 <span class="hlt">chondrite</span> Mokoia have large excesses of radiogenic chromium-53. These excesses indicate the in situ decay of short-lived manganese-53 (half-life = 3.7 million years) and define an initial 53Mn/55Mn ratio of 2.32 (+/-0.18) x 10(-6). This ratio is comparable to values for carbonates in CI and CM <span class="hlt">chondrites</span> and for several classes of differentiated meteorites. Mokoia fayalites formed 7 to 16 million years after <span class="hlt">Allende</span> calcium-aluminum-rich inclusions, during hydrothermal activity on a geologically active asteroid after <span class="hlt">chondritic</span> components had ceased forming in the solar nebula.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150018573','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150018573"><span id="translatedtitle">Identification of Highly Fractionated (18)O-Rich Silicate Grains in the Queen Alexandra Range 99177 CR3 <span class="hlt">Chondrite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nguyen, A. N.; Keller, L. P.; Messenger, S.; Rahman, Z.</p> <p>2015-01-01</p> <p><span class="hlt">Carbonaceous</span> <span class="hlt">chondrites</span> contain a mixture of solar system condensates, presolar grains, and primitive organic matter. The CR3 <span class="hlt">chondrite</span> QUE 99177 has undergone minimal al-teration [1], exemplified by abundant presolar silicates [2, 3] and anomalous organic matter [4]. Oxygen isotopic imaging studies of this meteorite have focused on finding submicrometer anomalous grains in fine-grained regions of thin sections. Here we present re-sults of an O isotopic survey of larger matrix grains.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014acm..conf...52B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014acm..conf...52B&link_type=ABSTRACT"><span id="translatedtitle">Thermal history of type-3 <span class="hlt">chondrites</span> in the NASA antarctic collection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bonal, L.; Quirico, E.; Montagnac, G.</p> <p>2014-07-01</p> <p><span class="hlt">Chondrites</span> are the most primitive meteorites. However, they were all modified in some ways by post-accretion geological processes operating on their asteroidal parent bodies. Hence, to decipher the formation(s) and origin(s) of their components, we must first understand how <span class="hlt">chondritic</span> materials were modified in their asteroidal parent bodies. The modifications induced by secondary processes should not be underestimated and have to be precisely estimated before any interpretation of <span class="hlt">chondrite</span> properties in terms of cosmochemistry. In particular, all <span class="hlt">chondrites</span> contain some organic components that were potentially chemically and physically modified through post-accretion processes. A thin understanding of the induced evolution is required to allow for pertinent comparisons with other primitive extraterrestrial materials, such as cometary grains, to finally address questions such as the origin of organics in the Solar System. Type 3 <span class="hlt">chondrites</span> experienced thermal metamorphism on their asteroidal parent body due to the radioactive decay of elements such as ^{26}Al. Temperatures higher than 300 °C were experienced on timescales of several thousands of years. Still, type 3 <span class="hlt">chondrites</span> remain as unequilibrated rocks and common mineralogical thermometers cannot be applied. The polyaromatic <span class="hlt">carbonaceous</span> matter is sensitive to thermal episodes (of long and short duration) experienced by the host meteorite. In particular, its structural order directly reflects the thermal history experienced on their parent bodies. The structural modification of the aromatic <span class="hlt">carbonaceous</span> matter towards a higher order is irreversible, and independent of the mineralogy and degree of aqueous alteration. It is mainly controlled by the peak metamorphic temperature. Moreover, under the assumption of fairly similar organic precursors among <span class="hlt">chondrites</span> of distinct groups, the structural order of polyaromatic organic matter allows for a direct comparison of their metamorphic grades. It is then possible</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920048243&hterms=zinc&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dzinc','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920048243&hterms=zinc&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dzinc"><span id="translatedtitle">Trace elements in <span class="hlt">chondritic</span> stratospheric particles - Zinc depletion as a possible indicator of atmospheric entry heating</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Flynn, G. J.; Sutton, S. R.</p> <p>1992-01-01</p> <p>Major-element abundances in 11 C, C?, and TCA cosmic dust particles have been measured using SEM and TEM energy dispersive X-ray (EDX) systems. The Fe/Ni ratio, when coupled with major element abundances, appears to be a useful discriminator of cosmic particles. Three particles classified as C?, but having Fe/Ni peak height ratios similar to those measured on the powdered <span class="hlt">Allende</span> meteorite sample in their HSC EDX spectra, exhibit <span class="hlt">chondritic</span> minor-/trace-element abundance patterns, suggesting they are extraterrestrial. The one particle classified as C-type, but without detectable Ni in its JSC EDX spectrum, exhibits an apparently nonchondritic minor-/trace-element abundance pattern. A class of particles that are <span class="hlt">chondritic</span> except for large depletions in the volatile elements Zn and S has been identified. It is likely that these particles condensed with a C1 abundance pattern and that Zn and S were removed by some subsequent process.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('//www.loc.gov/pictures/collection/hh/item/md1468.photos.193035p/','SCIGOV-HHH'); return false;" href="//www.loc.gov/pictures/collection/hh/item/md1468.photos.193035p/"><span id="translatedtitle">15. Balto. Div. East, Phila. Branch, Bridge No. 13A (<span class="hlt">Allender</span>) ...</span></a></p> <p><a target="_blank" href="http://www.loc.gov/pictures/collection/hh/">Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey</a></p> <p></p> <p></p> <p>15. Balto. Div. -East, Phila. Branch, Bridge No. 13-A (<span class="hlt">Allender</span>) Loreley, Md., General Plan. Baltimore: Office of Engineer of Bridges, 1942. Copy of drawing located at the Baltimore County Department of Public Works, Towson, Maryland. - <span class="hlt">Allender</span> Road Bridge, Spanning CSX Transportation railroad tracks at <span class="hlt">Allender</span> Road, White Marsh, Baltimore County, MD</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19870050802&hterms=Heymann&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DHeymann','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19870050802&hterms=Heymann&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DHeymann"><span id="translatedtitle">Carbon in dark inclusions of the <span class="hlt">Allende</span> meteorite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Heymann, D.; Van Der Stap, C. C. A. H.; Vis, R. N.; Verheul, H.</p> <p>1987-01-01</p> <p>Carbon contents of three dark inclusions (DI's) of the <span class="hlt">Allende</span> meteorite, measured chemically, range from 0.56 to 1.17 wt pct. When one includes the data reported by Bunch, Chang, and Ott (1980), the lower limit is 0.44 pct. The C-concentration map of a 1.6 x 1.6 sq mm area straddling the boundary of a DI and matrix, or of a DI and its dark halo, obtained with a C-12(d,p)C-13 nuclear microprobe, shows that the C-content of the core of the DI is very uniform, and that the C-content of the rim is 2.9 + or - 0.3 times larger. Variability of the C-content of matrix and matrix-like areas of <span class="hlt">Allende</span> appears to be the rule. DIs cannot be a reworked bulk <span class="hlt">Allende</span>, or a precursor for bulk <span class="hlt">Allende</span> without the addition or, respectively, removal of significant amounts of carbon. However, some type 1 DIs might be reworked <span class="hlt">Allende</span> matrix or precursor matter for that matrix.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013M%26PSA..76.5012M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013M%26PSA..76.5012M"><span id="translatedtitle">Halogens in CM <span class="hlt">Chondrites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Menard, J. M.; Caron, B.; Jambon, A.; Michel, A.; Villemant, B.</p> <p>2013-09-01</p> <p>We set up an extraction line of halogens (fluorine, chlorine) by pyrohydrolysis with 50 mg of rock. We analyzed 7 CM2 <span class="hlt">chondrites</span> found in Antarctica and found that the Cl content of meteorites with an intact fusion crust is higher than those without.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19890049163&hterms=Pu&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DPu','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19890049163&hterms=Pu&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DPu"><span id="translatedtitle">The early solar system abundance of Pu-244 as inferred from the St. Severin <span class="hlt">chondrite</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hudson, G. B.; Kennedy, B. M.; Podosek, F. A.; Hohenberg, C. M.</p> <p>1989-01-01</p> <p>The isotopic composition of Xe released in stepwise heating of neutron-irradiated samples of the St. Severin <span class="hlt">chondrite</span> was measured. This analysis shows that at the time of formation of most <span class="hlt">chondritic</span> meteorites, approximately 4.56 x 10 to the 9th yr ago, the atomic ratio of Pu-244/U-238 was 0.0068 + or - 0.0010 in <span class="hlt">chondritic</span> meteorites. This value is believed to be more reliable that inferred from earlier analyses of St. Severin and is the best estimate for the early solar system abundance of Pu-244. The comparison of Xe compositions between irradiated and unirradiated samples shows that the composition of trapped (ambient) Xe in St. Severin has a significantly lower value of Xe-136/Xe-130 than average <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.116...33H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.116...33H"><span id="translatedtitle">Visualisation and quantification of CV <span class="hlt">chondrite</span> petrography using micro-tomography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hezel, Dominik C.; Elangovan, Premkumar; Viehmann, Sebastian; Howard, Lauren; Abel, Richard L.; Armstrong, Robin</p> <p>2013-09-01</p> <p>Micro-computed tomography is a non-destructive technique that allows the study of 3D meteorite petrography. The technique produces a unique and instructive visualisation of the meteorite for quantifying its components. We studied the overall petrography of the two CV <span class="hlt">chondrites</span> <span class="hlt">Allende</span> and Mokoia to constrain their formation histories. A set of movies and stereographic images detail the 3D petrography. Component modal abundances agree with previous reports and modal abundance differences between <span class="hlt">Allende</span> and Mokoia support the chondrule-matrix complementarity and that chondrules and matrix formed from the same chemical reservoir. We identified two types of chondrules, a normal type and one where a normal type I or II chondrule is almost completely encapsulated by an opaque-rich layer. This layer was probably acquired during a late stage condensation process. The appearance of opaques in chondrules and matrix is different, not supporting a genetic relationships between these. Low abundances of compound chondrules (1.75 vol% in <span class="hlt">Allende</span> and 2.50 vol% in Mokoia) indicate low chondrule densities and/or low relative component velocities in chondrule formation regions. Porosities on a scale <10-20 μm allowed for only local aqueous alteration processes on the meteorite parent bodies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014M%26PS...49.1888S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014M%26PS...49.1888S"><span id="translatedtitle">Composition and clues to the origin of refractory metal nuggets extracted from <span class="hlt">chondritic</span> meteorites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schwander, D.; Berg, T.; Harries, D.; Schönhense, G.; Ott, U.</p> <p>2014-10-01</p> <p>Refractory metal nuggets (RMNs) contain elements, such as Os, Ir, Mo, and Ru, which are predicted to condense from a cooling gas of solar composition simultaneously with CAI-minerals. Berg et al. identified a large number of RMNs in acid-resistant residues of the Murchison meteorite and suggested that they are pristine condensates. In extending the work of these authors, we have improved the chemical extraction process to enrich the concentration of RMNs in the residue sample and prepared three additional RMN-rich residues from the <span class="hlt">chondritic</span> meteorites Murchison, <span class="hlt">Allende</span>, and Leoville. The results show that, while their origin is clearly solar, the compositions in detail of RMNs from all three meteorites do not match well with a simple condensation model based on equilibrium thermodynamics and ideal solid solution of all metals. Thus, we find that a primary formation by direct condensation, as suggested previously, is unlikely for most of the studied grains and that alternative scenarios should be considered in future work. The results also show that several, but not all, alloys from <span class="hlt">Allende</span> and Leoville have undergone processes, such as metamorphic oxidation and sulfidization in the meteoritic environment, in which they lost, e.g., W and Mo. For Murchison and several Leoville and <span class="hlt">Allende</span> RMNs, we propose a pristine nature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.189..359S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.189..359S"><span id="translatedtitle">Widespread evidence for high-temperature formation of pentlandite in <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schrader, Devin L.; Davidson, Jemma; McCoy, Timothy J.</p> <p>2016-09-01</p> <p>By investigating the compositional and textural evolution of sulfides within a wide range of relatively pristine, aqueously altered, and thermally metamorphosed <span class="hlt">chondrites</span> we constrain the equilibration temperatures of sulfide minerals and compare them to the metamorphic history of their host meteorite. Sulfides in Mighei-like <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> are complex as they equilibrated mostly between 100 and 135 °C, but some may have equilibrated at temperatures up to 600 °C. This is consistent with some CM <span class="hlt">chondrite</span> sulfides forming at high temperature during chondrule cooling and others during low-temperature aqueous alteration and/or annealing. Karoonda-like <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> sulfides equilibrated between 500 and 230 °C, which is consistent with formation during cooling and annealing after thermal metamorphism. Sulfides in the LL <span class="hlt">chondrites</span> equilibrated between 600 and 230 °C, and are consistent with formation during chondrule cooling for Semarkona (LL3.00) and during cooling after thermal metamorphism for the equilibrated samples (types 4-6). Sulfides in the Rumuruti-like (R) <span class="hlt">chondrites</span> equilibrated between 600 and 500 °C, and are consistent with formation after thermal metamorphism. The sulfides within the brachinite equilibrated between 600 and 400 °C, consistent with formation during cooling after thermal metamorphism. Contrary to the assertion that pentlandite is solely the product of low-temperature aqueous alteration in many <span class="hlt">chondrite</span> groups, this study suggests that most sulfides in <span class="hlt">chondrites</span> are formed at or upon cooling from high-temperature. The evaluation of a single mineral system within samples that retain petrographic context is vital to the interpretation of formation and alteration processes recorded by small extraterrestrial samples, such as those that have been returned by the spacecraft missions Stardust and Hayabusa and will be returned by OSIRIS-REx and Hayabusa2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20030110970&hterms=Digestion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DDigestion','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20030110970&hterms=Digestion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DDigestion"><span id="translatedtitle">Molybdenum Isotopic Composition of Iron Meteorites, <span class="hlt">Chondrites</span> and Refractory Inclusions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Becker, H.; Walker, R. J.</p> <p>2003-01-01</p> <p>Recent Mo isotopic studies of meteorites reported evidence for differences in isotopic compositions for whole rocks of some primitive and differentiated meteorites relative to terrestrial materials. Enrichments of r- and p-process isotopes of up to 3-4 units (e unit = parts in 10(exp 4) over s-process dominated isotopes are the most prominent features. Certain types of presolar grains show large enrichments in s-process isotopes, however, it was concluded on grounds of mass balance that incomplete digestion of such grains cannot explain the enrichments of r- and p-process isotopes in whole rocks of primitive <span class="hlt">chondrites</span>. If the reported variability in r- and p-process isotope enrichments reflects the true isotopic characteristics of the whole rocks, the implications are quite profound. It would suggest the presence of large scale Mo isotopic heterogeneity within the solar accretion disk with likely collateral effects for other elements. However, such effects were not found for Ru isotopes, nor for Zr isotopes. Another recent Mo isotopic study by multi collector ICP-MS could not confirm the reported deviations in <span class="hlt">Allende</span>, Murchison or iron meteorites. Here, we present new results for the Mo isotopic composition of iron meteorites, <span class="hlt">chondrites</span> and CAIs obtained by negative thermal ionization mass spectrometry (NTIMS). We discuss analytical aspects and the homogeneity of Mo isotopic compositions in solar system materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015M%26PS..tmp..240M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015M%26PS..tmp..240M"><span id="translatedtitle">Polymer amide in the <span class="hlt">Allende</span> and Murchison meteorites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McGeoch, Julie E. M.; McGeoch, Malcolm W.</p> <p>2015-11-01</p> <p>It has been proposed that exothermic gas phase polymerization of amino acids can occur in the conditions of a warm dense molecular cloud to form hydrophobic polymer amide (HPA) (McGeoch and McGeoch 2014). In a search for evidence of this presolar chemistry <span class="hlt">Allende</span> and Murchison meteorites and a volcano control were diamond burr-etched and Folch extracted for potential HPA yielding 85 unique peaks in the meteorite samples via matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI TOF/MS). The amino acids after acid hydrolysis in <span class="hlt">Allende</span> were below the level of detection but many of the <span class="hlt">Allende</span> peaks via the more sensitive MALDI/TOF analysis could be fitted to a polymer combination of glycine, alanine, and alpha-hydroxyglycine with high statistical significance. A similar significant fit using these three amino acids could not be applied to the Murchison data indicating more complex polymer chemistry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860049985&hterms=neon&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dneon','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860049985&hterms=neon&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dneon"><span id="translatedtitle">Discovery of solar wind neon in the <span class="hlt">Allende</span> meteorite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Heymann, D.; Palma, R. L.</p> <p>1986-01-01</p> <p>Insert gases have been measured in seven sieve fractions of a disaggregated sample of the <span class="hlt">Allende</span> meteorite. The disaggregation was done by ultrasonic treatment in water and by freeze-thawing. This sample consititutes the first gas-rich portion known to occur in the <span class="hlt">Allende</span> meteorite. The composition of the trapped neon is solar, i.e., Neon-B, and the gas-rich samples contain more trapped Ne-20 than Ar-36. The set of sieve fractions show an anticorrelation of Ne-20 content and grain size. Gas-richness seems to be quite common among the CV3 meteorites with <span class="hlt">Allende</span> added to the earlier known cases of Mokoia, Vigarano, and Efremovka.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160002405','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160002405"><span id="translatedtitle">A Raman Study of Carbonates and Organic Contents in Five CM <span class="hlt">Chondrites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chan, Q. H. S.; Zolensky, M. E.; Bodnar, R. J.; Farley, C.; Cheung, J. C. H.</p> <p>2016-01-01</p> <p>Carbonates comprise the second most abundant class of carbon-bearing phases in <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> after organic matter (approximately 2 wt.%), followed by other C-bearing phases such as diamond, silicon carbide, and graphite. Therefore, understanding the abundances of carbonates and the associated organic matter provide critical insight into the genesis of major <span class="hlt">carbonaceous</span> components in <span class="hlt">chondritic</span> materials. Carbonates in CM <span class="hlt">chondrites</span> mostly occur as calcite (of varying composition) and dolomite. Properly performed, Raman spectroscopy provides a non-destructive technique for characterizing meteorite mineralogy and organic chemistry. It is sensitive to many <span class="hlt">carbonaceous</span> phases, allows the differentiation of organic from inorganic materials, and the interpretation of their spatial distribution. Here, with the use of Raman spectroscopy, we determine the structure of the insoluble organic matter (IOM) in the matrix and carbonate phases in five CM <span class="hlt">chondrites</span>: Jbilet Winselwan, Murchison, Nogoya, Santa Cruz, and Wisconsin Range (WIS) 91600, and interpret the relative timing of carbonate precipitation and the extent of the associated alteration events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19900043793&hterms=carbon+magnetite&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dcarbon%2Bmagnetite','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19900043793&hterms=carbon+magnetite&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dcarbon%2Bmagnetite"><span id="translatedtitle">Carbon-rich aggregates in type 3 ordinary <span class="hlt">chondrites</span> - Characterization, origins, and thermal history</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brearley, Adrian J.</p> <p>1990-01-01</p> <p>Carbon-rich aggregates from three type 3.4-3.6 ordinary <span class="hlt">chondrites</span> and two <span class="hlt">chondritic</span> clasts have been characterized in detail, using TEM techniques. The aggregates in all the meteorites studied range in size from 5-1000 microns and consist of a fine scale intergrowth of poorly graphitized carbon, amorphous carbon, Fe,Ni metal, and minor chromite. Contrary to previous reports, well-crystallized graphite and magnetite are absent. The association of Fe,Ni metal and <span class="hlt">carbonaceous</span> material suggests that the original <span class="hlt">carbonaceous</span> material may have formed by Fischer-Tropsch (FT) type reactions at low temperatures (less than 400 K), possibly in the solar nebula. This <span class="hlt">carbonaceous</span> material probably consisted of a complex mixture of hydrocarbons, kerogen-like material, and other complex organic molecules. The aggregates were subsequently accreted onto the ordinary <span class="hlt">chondrite</span> parent bodies and underwent planetary thermal processing which resulted in the catalytic graphitization of hydrocarbons, in the presence of Fe,Ni metal, to produce poorly graphitized carbon. None of the meteorites studied experienced temperatures sufficiently high to produce crystalline, ordered graphite. Using the empirical geothermometer of Rietmeijer and Mackinnon (1985), the measured d(002) spacings of poorly graphitized carbon show that graphitization occurred at temperatures between 300 and 450 C. This range of temperatures is significantly lower than the generally quoted metamorphic temperatures for type 3.4-3.6 ordinary <span class="hlt">chondrites</span> (about 450-500 C).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015psrd.reptE.180D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015psrd.reptE.180D"><span id="translatedtitle"><span class="hlt">Chondritic</span> Asteroids--When Did Aqueous Alteration Happen?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Doyle, P. M.</p> <p>2015-06-01</p> <p>Using a synthesized fayalite (Fe2SiO4) standard for improved 53Mn-53Cr radiometric age dating, Patricia Doyle (previously at the University of Hawaii and now at the University of Cape Town, South Africa) and coauthors from Hawaii, the National Astronomical Observatory of Japan, University of Chicago, and Lawrence Livermore National Laboratory in California, analyzed aqueously formed fayalite in the ordinary <span class="hlt">chondrite</span> Elephant Moraine 90161 (L3.05) and in the <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> Asuka 881317 (CV3) and MacAlpine Hills 88107 (CO3-like) from Antarctica. The data obtained indicate that liquid water existed - and aqueous alteration started - on the <span class="hlt">chondritic</span> parent bodies about three million years earlier than previously determined. This discovery has implications for understanding when and where the asteroids accreted. The 53Mn-53Cr chronology of <span class="hlt">chondrite</span> aqueous alteration, combined with thermodynamic calculations and physical modeling, signifies that hydrated asteroids, at least those sampled by meteorites, accreted in the inner Solar System (2-4 AU) near the main asteroid belt 2-4 million years after the beginning of the Solar System, rather than migrating inward after forming in the Solar System's colder, outer regions beyond Jupiter's present orbit (5-15 AU).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3228457','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3228457"><span id="translatedtitle">Establishing a molecular relationship between <span class="hlt">chondritic</span> and cometary organic solids</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cody, George D.; Heying, Emily; Alexander, Conel M. O.; Nittler, Larry R.; Kilcoyne, A. L. David; Sandford, Scott A.</p> <p>2011-01-01</p> <p>Multidimensional solid-state NMR spectroscopy is used to refine the identification and abundance determination of functional groups in insoluble organic matter (IOM) isolated from a <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> (Murchison, CM2). It is shown that IOM is composed primarily of highly substituted single ring aromatics, substituted furan/pyran moieties, highly branched oxygenated aliphatics, and carbonyl groups. A pathway for producing an IOM-like molecular structure through formaldehyde polymerization is proposed and tested experimentally. Solid-state 13C NMR analysis of aqueously altered formaldehyde polymer reveals considerable similarity with <span class="hlt">chondritic</span> IOM. Carbon X-ray absorption near edge structure spectroscopy of formaldehyde polymer reveals the presence of similar functional groups across certain Comet 81P/Wild 2 organic solids, interplanetary dust particles, and primitive IOM. Variation in functional group concentration amongst these extraterrestrial materials is understood to be a result of various degrees of processing in the parent bodies, in space, during atmospheric entry, etc. These results support the hypothesis that <span class="hlt">chondritic</span> IOM and cometary refractory organic solids are related chemically and likely were derived from formaldehyde polymer. The fine-scale morphology of formaldehyde polymer produced in the experiment reveals abundant nanospherules that are similar in size and shape to organic nanoglobules that are ubiquitous in primitive <span class="hlt">chondrites</span>. PMID:21464292</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140004413','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140004413"><span id="translatedtitle">On the Relationship between Cosmic Ray Exposure Ages and Petrography of CM <span class="hlt">Chondrites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Takenouchi, A.; Zolensky, M. E.; Nishiizumi, K.; Caffee, M.; Velbel, M. A.; Ross, K.; Zolensky, A.; Lee, L.; Imae, N.; Yamaguchi, A.; Mikouchi, T.</p> <p>2014-01-01</p> <p><span class="hlt">Carbonaceous</span> (C) <span class="hlt">chondrites</span> are potentially the most primitive among <span class="hlt">chondrites</span> because they mostly escaped thermal metamorphism that affected the other <span class="hlt">chondrite</span> groups. C <span class="hlt">chondrites</span> are chemically distinguished from other <span class="hlt">chondrites</span> by their high Mg/Si ratios and refractory elements, and have experienced various degrees of aqueous alteration. They are subdivided into eight subgroups (CI, CM, CO, CV, CK, CR, CB and CH) based on major element and oxygen isotopic ratios. Their elemental ratios vary over a wide range, in contrast to those of ordinary and enstatite <span class="hlt">chondrites</span> which are relatively uniform. It is critical to know how many separate bodies are represented by the C <span class="hlt">chondrites</span>. In this study we defined 4 distinct cosmic-ray exposure (CRE) age groups of CMs and systematically characterized the petrography in each of the 4 CRE age groups to determine whether the groups have significant petrographic differences with such differences probably reflecting different parent body (asteroid) geological processing, or multiple original bodies. We have reported the results of a preliminary grouping at the NIPR Symp. in 2013 [3], however, we revised the grouping and here report our new results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23141337','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23141337"><span id="translatedtitle">Determination of 11 major and minor elements in <span class="hlt">chondritic</span> meteorites by inductively coupled plasma mass spectrometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wolf, Stephen F; Compton, Joseph R; Gagnon, Christopher J L</p> <p>2012-10-15</p> <p>We have developed a new method for the quantification of 11 major and minor elements (Na, Mg, Al, P, S, K, Ca, Cr, Mn, Fe, and Ni) in <span class="hlt">chondritic</span> meteorites by ICPMS using external calibration with a matrix-matched standard prepared from the <span class="hlt">Allende</span> Standard Reference Meteorite. We have demonstrated the method's accuracy and assessed three different measures of precision by performing replicate dissolutions and analyses of 0.10-g samples of a homogenized samples of the CM2 meteorite Murchison and compared our results to literature values. We subsequently applied this method to the analysis of a set of four <span class="hlt">chondritic</span> meteorites possessing a relatively wide range of <span class="hlt">chondritic</span> compositions with results in accord with previously published values. Because our method is designed to use the same instrumentation and can use samples and standards prepared according to methods previously validated for the determination of a comprehensive suite of minor, trace, moderately and highly volatile trace elements (i.e., Li, Sc, Ti, V, Mn, Co, Cu, Zn, Ga, As, Se, Rb, Sr, Y, Zr, Nb, Mo, Ru, Pd, Ag, Cd, In, Sn, Sb, Te, Cs, Ba, all 14 naturally occurring lanthanoids, Hf, W, Re, Ir, Pt, Tl, Bi, Th, and U) it complements these methods and allows a single laboratory to determine the concentrations of 60 elements in semimicroscopic amounts of <span class="hlt">chondritic</span> material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23141337','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23141337"><span id="translatedtitle">Determination of 11 major and minor elements in <span class="hlt">chondritic</span> meteorites by inductively coupled plasma mass spectrometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wolf, Stephen F; Compton, Joseph R; Gagnon, Christopher J L</p> <p>2012-10-15</p> <p>We have developed a new method for the quantification of 11 major and minor elements (Na, Mg, Al, P, S, K, Ca, Cr, Mn, Fe, and Ni) in <span class="hlt">chondritic</span> meteorites by ICPMS using external calibration with a matrix-matched standard prepared from the <span class="hlt">Allende</span> Standard Reference Meteorite. We have demonstrated the method's accuracy and assessed three different measures of precision by performing replicate dissolutions and analyses of 0.10-g samples of a homogenized samples of the CM2 meteorite Murchison and compared our results to literature values. We subsequently applied this method to the analysis of a set of four <span class="hlt">chondritic</span> meteorites possessing a relatively wide range of <span class="hlt">chondritic</span> compositions with results in accord with previously published values. Because our method is designed to use the same instrumentation and can use samples and standards prepared according to methods previously validated for the determination of a comprehensive suite of minor, trace, moderately and highly volatile trace elements (i.e., Li, Sc, Ti, V, Mn, Co, Cu, Zn, Ga, As, Se, Rb, Sr, Y, Zr, Nb, Mo, Ru, Pd, Ag, Cd, In, Sn, Sb, Te, Cs, Ba, all 14 naturally occurring lanthanoids, Hf, W, Re, Ir, Pt, Tl, Bi, Th, and U) it complements these methods and allows a single laboratory to determine the concentrations of 60 elements in semimicroscopic amounts of <span class="hlt">chondritic</span> material. PMID:23141337</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150001936','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150001936"><span id="translatedtitle">Early Size Distributions of Chondrule Subgroups Overprinted by the Final Accumulation Process of Particle Components in <span class="hlt">Allende</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>McCain, K. A.; Simon, J. I.; Cuzzi, J. N</p> <p>2015-01-01</p> <p>Populations of compositionally distinct particles are fundamental components of undifferentiated <span class="hlt">chondritic</span> meteorites. Many theories explain the formation of <span class="hlt">chondrites</span>, one class of which includes mechanisms for sorting the component particles in the solar nebula prior to their accretion. Mechanisms include sorting by mass, turbulent concentration, X-winds, and photophoresis, which will produce characteristic distributions of observable properties such as particle size. Distinguishing processes that occur in specific astrophysical environments requires characterization of particle types, which include refractory Ca-Al-rich Inclusions (CAIs) and less-refractory chondrules. Previous investigations of modal abundances of CAIs and chondrules exist, but differences within and between these two groups, both of which are made up of diverse subgroups with different thermal histories and chemical compositions, remain mostly unstudied. The presence of rims, a significant event occurring after the formation of at least some chondrules, have also yet to be considered with respect to sorting. Here we present the sizes of CAIs and chondrules in <span class="hlt">Allende</span> with attention to the smallest sizes, subgroups, and particle rims.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EPSC...10..166V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EPSC...10..166V"><span id="translatedtitle">Hydrothermal alteration experiments: tracking the path from interstellar to <span class="hlt">chondrites</span> organics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vinogradoff, V.; Bernard, S.; Le Guillou, C.; Jaber, M.; Remusat, L.</p> <p>2015-10-01</p> <p>Organic molecules are detected in primitive <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>. The origin of these organics, whether formed prior the accretion phase, or in-situ on the parent body, is still a matter of debate. We have investigated experimentally the chemical evolution of interstellar organic molecules submitted to hydrothermal conditions, mimicking asteroidal alteration (T<200°C). In particular, we want to assess the potential catalytic role of clays minerals in the polymerization/degradation of organics. Hexamethylenetetramine (HMT, compound of C-N bonds) is used as a plausible interstellar precursors from icy grains. Experimental products reveal a large diversity of molecules, including nitrogen organic molecules similar to those found in <span class="hlt">chondrites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120001815','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120001815"><span id="translatedtitle">The Oxygen Isotopic Composition of MIL 090001: A CR2 <span class="hlt">Chondrite</span> with Abundant Refractory Inclusions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Keller, Lindsay P.; McKeegan, K. D.; Sharp, Z. D.</p> <p>2012-01-01</p> <p>MIL 090001 is a large (>6 kg) <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> that was classified as a member of the CV reduced subgroup (CVred) that was recovered during the 2009-2010 ANSMET field season [1]. Based on the abundance of refractory inclusions and the extent of aqueous alteration, Keller [2] suggested a CV2 classification. Here we report additional mineralogical and petrographic data for MIL 090001, its whole-rock oxygen isotopic composition and ion microprobe analyses of individual phases. The whole rock oxygen isotopic analyses show that MIL 090001 should be classified as a CR <span class="hlt">chondrite</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22460899','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22460899"><span id="translatedtitle">Evidence against a <span class="hlt">chondritic</span> Earth.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Campbell, Ian H; O'Neill, Hugh St C</p> <p>2012-03-28</p> <p>The (142)Nd/(144)Nd ratio of the Earth is greater than the solar ratio as inferred from <span class="hlt">chondritic</span> meteorites, which challenges a fundamental assumption of modern geochemistry--that the composition of the silicate Earth is '<span class="hlt">chondritic</span>', meaning that it has refractory element ratios identical to those found in <span class="hlt">chondrites</span>. The popular explanation for this and other paradoxes of mantle geochemistry, a hidden layer deep in the mantle enriched in incompatible elements, is inconsistent with the heat flux carried by mantle plumes. Either the matter from which the Earth formed was not <span class="hlt">chondritic</span>, or the Earth has lost matter by collisional erosion in the later stages of planet formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Icar..237..278B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Icar..237..278B"><span id="translatedtitle">Ion irradiation of <span class="hlt">Allende</span> meteorite probed by visible, IR, and Raman spectroscopies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brunetto, R.; Lantz, C.; Ledu, D.; Baklouti, D.; Barucci, M. A.; Beck, P.; Delauche, L.; Dionnet, Z.; Dumas, P.; Duprat, J.; Engrand, C.; Jamme, F.; Oudayer, P.; Quirico, E.; Sandt, C.; Dartois, E.</p> <p>2014-07-01</p> <p>Little is known about <span class="hlt">carbonaceous</span> asteroids weathering in space as previous studies have struggled to define a general spectral trend among dark surfaces. Here we present experiments on ion irradiation of the <span class="hlt">Allende</span> meteorite, performed using 40 keV He+ and Ar+ ions, as a simulation of solar wind irradiation of primitive bodies surfaces. We used different fluences up to 3 × 1016 ions/cm2, corresponding to short timescales of ∼103-104 yrs in the main asteroid belt. Samples were analyzed before and after irradiation using visible to far-IR (0.4-50 μm) reflectance spectroscopy, and Raman micro-spectroscopy. Similarly to what observed in previous experiments, results show a reddening and darkening of VIS-NIR reflectance spectra. These spectral variations are however comparable to other spectral variations due to viewing geometry, grain size, and sample preparation, suggesting an explanation for the contradictory space weathering studies of dark asteroids. After irradiation, the infrared bands of the matrix olivine silicates change profile and shift to longer wavelength, possibly as a consequence of a more efficient sputtering effect on Mg than Fe (lighter and more volatile species are preferentially sputtered backwards) and/or preferential amorphization of Mg-rich olivine. Spectral variations are compatible with the Hapke weathering model. Raman spectroscopy shows that the <span class="hlt">carbonaceous</span> component is substantially affected by irradiation: different degrees of de-ordering are produced as a function of dose, to finally end with a highly disordered carbon. All observed modifications seem to scale with the nuclear elastic dose.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT.......102J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT.......102J"><span id="translatedtitle">Timescales and conditions for the aqueous alteration of <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jilly, Christine E.</p> <p></p> <p>It has become well-recognized that water played a critical role in the early geological evolution of materials through observation of hydrated phases in <span class="hlt">chondritic</span> meteorites. However, details about the mechanism, timing, and conditions of aqueous alteration are poorly constrained. This dissertation investigates water-driven processes in Renazzo-like (CR) <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>, with some comparison to the heavily altered and Mighei-like (CM) <span class="hlt">chondrites</span>. CR <span class="hlt">chondrites</span> were chosen as the focus of this study, as they are the only <span class="hlt">chondrite</span> group to range from practically anhydrous to completely hydrated, providing petrographic context for the aqueous alteration process. The central goal of the thesis is to elucidate the complete mechanism of aqueous alteration, from primary anhydrous components to secondary minerals. This research uses a variety of micro-analytical techniques to address three main objectives: 1) to detail the petrographic context, 2) to quantify the onset and duration of alteration using radiometric dating, and 3) to constrain the fluid chemistry and conditions for aqueous alteration. On a microscopic scale, fine-grained matrices and glassy mesostases were the first phases to become altered, allowing for elemental transport over short distances (< 100 microns). As alteration progressed, the iron-metal was oxidized, and silicate phenocrysts were pseudomorphically replaced. 53Mn-53 Cr radiometric dating of secondary carbonates in CR <span class="hlt">chondrites</span> show that aqueous alteration began quickly after accretion of the parent body, ~4 Myr after the beginning of the Solar System. This is contemporaneous with dolomite formation in the CM <span class="hlt">chondrite</span> Sutter's Mill and with carbonate formation in other CM <span class="hlt">chondrites</span>. However, the calcite age from a heavily hydrated CR lithology indicates that late-stage alteration occurred ~12 Myr after the beginning of the Solar System. The oxygen isotopic compositions of magnetite and carbonate minerals reveal that altering fluid</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11540421','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11540421"><span id="translatedtitle">Fullerenes, fulleranes and polycyclic aromatic hydrocarbons in the <span class="hlt">Allende</span> meteorite.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Becker, L; Bunch, T E</p> <p>1997-07-01</p> <p>In this paper, we confirm our earlier observations of fullerenes (C60 and C70) in the <span class="hlt">Allende</span> meteorite (Becker et al., 1994a, 1995). Fullerene C60 was also detected in two separate C-rich (approximately 0.5-1.0%) dark inclusions (Heymann et al., 1987) that were hand picked from the <span class="hlt">Allende</span> sample. The amounts of C60 detected were approximately 5 and approximately 10 ppb, respectively, which is considerably less than what was detected in the <span class="hlt">Allende</span> 15/21 sample (approximately 100 ppb; Becker et al., 1994a, 1995). This suggests that fullerenes are heterogeneously distributed in the meteorite. In addition, we present evidence for fulleranes, (C60Hx), detected in separate samples by laser desorption (reflectron) time-of-flight (TOF) mass spectrometry (LDMS). The LDMS spectra for the <span class="hlt">Allende</span> extracts were remarkably similar to the spectra generated for the synthetic fullerane mixtures. Several fullerane products were synthesized using a Rh catalyst (Becker et al., 1993a) and separated using high-performance liquid chromatography (HPLC). Polycyclic aromatic hydrocarbons (PAHs) were also observed ppm levels) that included benzofluoranthene and corannulene, a cup-shaped molecule that has been proposed as a precursor molecule to the formation of fullerenes in the gas phase (Pope et al., 1993).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997M%26PS...32..479B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997M%26PS...32..479B"><span id="translatedtitle">Fullerenes, fulleranes and PAHs in the <span class="hlt">Allende</span> meteorite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Becker, Luann; Bunch, T. E.</p> <p>1997-07-01</p> <p>In this paper we confirm our earlier observations of fullerenes (C60 and C70) in the <span class="hlt">Allende</span> meteorite (Becker et al., 1994a, 1995). C60 was also detected in two separate carbon-rich (~0.5 - 1.0 %) dark inclusions (Heymann et al., 1987) that were hand picked from the <span class="hlt">Allende</span> sample. The amounts of C60 detected were ~5 and ~10 ppb respectively, considerably less then what was detected in the <span class="hlt">Allende</span> 15/21 sample (~100 ppb; Becker et al., 1994a, 1995), suggesting that fullerenes are heterogeneously distributed in the meteorite. In addition, we present evidence for fulleranes (C60Hx), detected in separate samples by laser desorption (reflectron) time-of-flight (TOF) mass spectrometry (LDMS). LDMS spectra for the <span class="hlt">Allende</span> extracts were remarkably similar to the spectra generated for the synthetic fullerane mixtures. Several fullerane products were synthesized using a rhodium catalyst (Becker et al., 1993a) and separated using high performance liquid chromatography (HPLC). Polycyclic aromatic hydrocarbons (PAHs) were also observed (ppm levels) including benzofluoranthene and corannulene, a cup-shaped molecule that has been proposed as a precursor molecule to the formation of fullerenes in the gas phase (Pope et al., 1993).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040089419&hterms=HPLC&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DHPLC','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040089419&hterms=HPLC&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DHPLC"><span id="translatedtitle">Fullerenes, fulleranes and polycyclic aromatic hydrocarbons in the <span class="hlt">Allende</span> meteorite</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Becker, L.; Bunch, T. E.</p> <p>1997-01-01</p> <p>In this paper, we confirm our earlier observations of fullerenes (C60 and C70) in the <span class="hlt">Allende</span> meteorite (Becker et al., 1994a, 1995). Fullerene C60 was also detected in two separate C-rich (approximately 0.5-1.0%) dark inclusions (Heymann et al., 1987) that were hand picked from the <span class="hlt">Allende</span> sample. The amounts of C60 detected were approximately 5 and approximately 10 ppb, respectively, which is considerably less than what was detected in the <span class="hlt">Allende</span> 15/21 sample (approximately 100 ppb; Becker et al., 1994a, 1995). This suggests that fullerenes are heterogeneously distributed in the meteorite. In addition, we present evidence for fulleranes, (C60Hx), detected in separate samples by laser desorption (reflectron) time-of-flight (TOF) mass spectrometry (LDMS). The LDMS spectra for the <span class="hlt">Allende</span> extracts were remarkably similar to the spectra generated for the synthetic fullerane mixtures. Several fullerane products were synthesized using a Rh catalyst (Becker et al., 1993a) and separated using high-performance liquid chromatography (HPLC). Polycyclic aromatic hydrocarbons (PAHs) were also observed ppm levels) that included benzofluoranthene and corannulene, a cup-shaped molecule that has been proposed as a precursor molecule to the formation of fullerenes in the gas phase (Pope et al., 1993).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20000081025&hterms=Noble+gases&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DNoble%2Bgases','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20000081025&hterms=Noble+gases&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DNoble%2Bgases"><span id="translatedtitle">Fullerenes and Noble Gases in the Murchison and <span class="hlt">Allende</span> Meteorites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Becker, Luann; Poreda, Robert J.; Bunch, Ted E.</p> <p>2000-01-01</p> <p>In this work we report the detection of fullerenes (C60 to C250) in the Murchison and <span class="hlt">Allende</span> meteorites. By exploiting the unique ability of these molecules to trap noble gases, we have determined that fullerene is indeed a new carrier phase for noble gases in meteorites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11540046','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11540046"><span id="translatedtitle">Influence of Murchison or <span class="hlt">Allende</span> minerals on hydrogen-deuterium exchange of amino acids.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lerner, N R</p> <p>1995-04-01</p> <p>Deuterium-enriched amino acids occur in the Murchison <span class="hlt">carbonaceous</span> chrondrite. This meteorite underwent a period of aqueous alteration with isotopically light water. With the objective of setting limits on the conditions of aqueous alteration, the exchange of the carbon-bonded hydrogen atoms of amino acids with D2O has been studied from 295 to 380 K as a function of time and meteorite/heavy water ratio. The amount of Murchison or <span class="hlt">Allende</span> dust present has a significant effect on the rate and amount of hydrogen-deuterium exchange observed. At elevated temperatures, the alpha-hydrogens of all the amino acids studied were found to exchange with deuterium. In glycine and aspartic acid, this process resulted in total exchange of the carbon-bonded hydrogen. A completely deuterated isotopomer of alanine was produced in significant quantities only when the rock/water ratio was greater than 0.5. No exchange of carbon-bonded hydrogens was observed in the case of amino acids which do not possess an alpha-hydrogen atom. The rates of H/D exchange for amino acids observed here did not correspond to deuterium enrichment of the amino acids in the Murchison meteorite. These results suggest that H/D exchange with water had a negligible effect on the observed deuterium enrichment of amino acids found in Murchison and that the temperature at which the amino acids were exposed to liquid water was close to 273 K.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160002638','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160002638"><span id="translatedtitle">Organic Analysis in the Miller Range 090657 CR2 <span class="hlt">Chondrite</span>: Part 3 C and N Isotopic Imaging</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Messenger, S.; Nakamura-Messenger, K.; Elsila, J. E.; Berger, E. L.; Burton, A. S.; Clemett, S. J.; Cao, T.</p> <p>2016-01-01</p> <p>Primitive <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> contain a wide variety of organic material, ranging from soluble discrete molecules to insoluble nanoglobules of macro-molecular carbon. The relationship between the soluble organic molecules, macromolecular organic material, and host minerals are poorly understood. Large H, C and N isotopic anomalies suggest some organic components formed in low-T interstellar or outer Solar System environments. The highest isotope anomalies occur in m-scale inclusions in the most primitive materials, such as cometary dust and the least altered <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>. Often, the hosts of these isotopically anomalous 'hotspots' are discrete organic nanoglobules that probably formed in the outermost reaches of the protosolar disk or cold molecular cloud. Molecular and isotopic studies of meteoritic organic matter are aimed at identifying the chemical properties and formation processes of interstellar organic materials and the subsequent chemical evolutionary pathways in various Solar System environments. The combination of soluble and insoluble analyses with in situ and bulk studies provides powerful constraints on the origin and evolution of organic matter in the Solar System. Using macroscale extraction and analysis techniques as well as microscale in situ observations we have been studying both insoluble and soluble organic material in primitive astromaterial samples. Here, we present results of bulk C and N isotopic measurements and coordinated in situ C and N isotopic imaging and mineralogical and textural studies of <span class="hlt">carbonaceous</span> materials in a Cr2 <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span>. In accompanying abstracts we discuss the morphology and distribution of <span class="hlt">carbonaceous</span> components and soluble organic species of this meteorite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930069284&hterms=metamorphism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmetamorphism','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930069284&hterms=metamorphism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmetamorphism"><span id="translatedtitle">Effect of metamorphism on isolated olivine grains in CO3 <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, Rhian H.</p> <p>1993-01-01</p> <p>The presence of a metamorphic sequence in the CO3 <span class="hlt">chondrite</span> group has been shown previously to result in changes in properties of chondrule silicates. However, the role of isolated olivine grains during metamorphism of these <span class="hlt">chondrites</span> has not been addressed. Isolated olivine grains in two metamorphosed CO3 <span class="hlt">chondrites</span>, Lance and Isna, have been investigated in this study in order to assess the compositional properties of isolated olivine grains that may be attributable to metamorphism. Compositional changes in isolated olivines with increasing petrologic subtype are very similar to changes in chondrule olivines in the same <span class="hlt">chondrites</span>. Olivine compositions from all occurrences (chondrules, isolated grains, and matrix) converge with increasing petrologic subtype. The degree of equilibration of minor elements is qualitatively related to the diffusion rate of each element in olivine, suggesting that diffusion-controlled processes are the most important processes responsible for compositional changes within the metamorphic sequence. The data are consistent with metamorphism taking place in a closed system on the CO3 <span class="hlt">chondrite</span> parent body. Fe-poor olivine grains in metamorphosed <span class="hlt">chondrites</span> are characterized by an Fe-rich rim, which is the result of diffusion of Fe into the grains from Fe-rich matrix. In some instances, 'complex', Fe-rich rims have been identified, which appear to have originated as igneous overgrowths and subsequently to have been overprinted by diffusion processes during metamorphism. Processes experienced by CO3 <span class="hlt">chondrites</span> are more similar to those experienced by the ordinary <span class="hlt">chondrites</span> than to those encountered by other <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>, such as the CV3 group.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011GeCoA..75.6556W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011GeCoA..75.6556W"><span id="translatedtitle">Petrology and oxygen isotope compositions of chondrules in E3 <span class="hlt">chondrites</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weisberg, Michael K.; Ebel, Denton S.; Connolly, Harold C.; Kita, Noriko T.; Ushikubo, Takayuki</p> <p>2011-11-01</p> <p>Chondrules in E3 <span class="hlt">chondrites</span> differ from those in other <span class="hlt">chondrite</span> groups. Many contain near-pure endmember enstatite (Fs <1). Some contain Si-bearing FeNi metal, Cr-bearing troilite, and, in some cases Mg, Mn- and Ca-sulfides. Olivine and more FeO-rich pyroxene grains are present but much less common than in ordinary or <span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> chondrules. In some cases, the FeO-rich grains contain dusty inclusions of metal. The oxygen three-isotope ratios (δ 18O, δ 17O) of olivine and pyroxene in chondrules from E3 <span class="hlt">chondrites</span>, which are measured using a multi-collection SIMS, show a wide range of values. Most enstatite data plots on the terrestrial fractionation (TF) line near whole rock values and some plot near the ordinary <span class="hlt">chondrite</span> region on the 3-isotope diagram. Pyroxene with higher FeO contents (˜2-10 wt.% FeO) generally plots on the TF line similar to enstatite, suggesting it formed locally in the EC (enstatite <span class="hlt">chondrite</span>) region and that oxidation/reduction conditions varied within the E3 <span class="hlt">chondrite</span> chondrule-forming region. Olivine shows a wide range of correlated δ 18O and δ 17O values and data from two olivine-bearing chondrules form a slope ˜1 mixing line, which is approximately parallel to but distinct from the CCAM (<span class="hlt">carbonaceous</span> <span class="hlt">chondrite</span> anhydrous mixing) line. We refer to this as the ECM (enstatite <span class="hlt">chondrite</span> mixing) line but it also may coincide with a line defined by chondrules from Acfer 094 referred to as the PCM (Primitive <span class="hlt">Chondrite</span> Mineral) line ( Ushikubo et al., 2011). The range of O isotope compositions and mixing behavior in E3 chondrules is similar to that in O and C <span class="hlt">chondrite</span> groups, indicating similar chondrule-forming processes, solid-gas mixing and possibly similar 16O-rich precursors solids. However, E3 chondrules formed in a distinct oxygen reservoir. Internal oxygen isotope heterogeneity was found among minerals from some of the chondrules in E3 <span class="hlt">chondrites</span> suggesting incomplete melting of the chondrules, survival of minerals from</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NatCo...6E8567L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatCo...6E8567L"><span id="translatedtitle">The deuterium/hydrogen distribution in <span class="hlt">chondritic</span> organic matter attests to early ionizing irradiation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Laurent, Boris; Roskosz, Mathieu; Remusat, Laurent; Robert, François; Leroux, Hugues; Vezin, Hervé; Depecker, Christophe; Nuns, Nicolas; Lefebvre, Jean-Marc</p> <p>2015-10-01</p> <p>Primitive <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> contain a large array of organic compounds dominated by insoluble organic matter (IOM). A striking feature of this IOM is the systematic enrichment in deuterium compared with the solar hydrogen reservoir. This enrichment has been taken as a sign of low-temperature ion-molecule or gas-grain reactions. However, the extent to which Solar System processes, especially ionizing radiation, can affect D/H ratios is largely unknown. Here, we report the effects of electron irradiation on the hydrogen isotopic composition of organic precursors containing different functional groups. From an initial terrestrial composition, overall D-enrichments and differential intramolecular fractionations comparable with those measured in the Orgueil meteorite were induced. Therefore, ionizing radiation can quantitatively explain the deuteration of organics in some <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>. For these meteorites, the precursors of the IOM may have had the same isotopic composition as the main water reservoirs of the inner Solar System.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26461170','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26461170"><span id="translatedtitle">The deuterium/hydrogen distribution in <span class="hlt">chondritic</span> organic matter attests to early ionizing irradiation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Laurent, Boris; Roskosz, Mathieu; Remusat, Laurent; Robert, François; Leroux, Hugues; Vezin, Hervé; Depecker, Christophe; Nuns, Nicolas; Lefebvre, Jean-Marc</p> <p>2015-10-13</p> <p>Primitive <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> contain a large array of organic compounds dominated by insoluble organic matter (IOM). A striking feature of this IOM is the systematic enrichment in deuterium compared with the solar hydrogen reservoir. This enrichment has been taken as a sign of low-temperature ion-molecule or gas-grain reactions. However, the extent to which Solar System processes, especially ionizing radiation, can affect D/H ratios is largely unknown. Here, we report the effects of electron irradiation on the hydrogen isotopic composition of organic precursors containing different functional groups. From an initial terrestrial composition, overall D-enrichments and differential intramolecular fractionations comparable with those measured in the Orgueil meteorite were induced. Therefore, ionizing radiation can quantitatively explain the deuteration of organics in some <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>. For these meteorites, the precursors of the IOM may have had the same isotopic composition as the main water reservoirs of the inner Solar System.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26461170','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26461170"><span id="translatedtitle">The deuterium/hydrogen distribution in <span class="hlt">chondritic</span> organic matter attests to early ionizing irradiation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Laurent, Boris; Roskosz, Mathieu; Remusat, Laurent; Robert, François; Leroux, Hugues; Vezin, Hervé; Depecker, Christophe; Nuns, Nicolas; Lefebvre, Jean-Marc</p> <p>2015-01-01</p> <p>Primitive <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> contain a large array of organic compounds dominated by insoluble organic matter (IOM). A striking feature of this IOM is the systematic enrichment in deuterium compared with the solar hydrogen reservoir. This enrichment has been taken as a sign of low-temperature ion-molecule or gas-grain reactions. However, the extent to which Solar System processes, especially ionizing radiation, can affect D/H ratios is largely unknown. Here, we report the effects of electron irradiation on the hydrogen isotopic composition of organic precursors containing different functional groups. From an initial terrestrial composition, overall D-enrichments and differential intramolecular fractionations comparable with those measured in the Orgueil meteorite were induced. Therefore, ionizing radiation can quantitatively explain the deuteration of organics in some <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>. For these meteorites, the precursors of the IOM may have had the same isotopic composition as the main water reservoirs of the inner Solar System. PMID:26461170</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4633821','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4633821"><span id="translatedtitle">The deuterium/hydrogen distribution in <span class="hlt">chondritic</span> organic matter attests to early ionizing irradiation</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Laurent, Boris; Roskosz, Mathieu; Remusat, Laurent; Robert, François; Leroux, Hugues; Vezin, Hervé; Depecker, Christophe; Nuns, Nicolas; Lefebvre, Jean-Marc</p> <p>2015-01-01</p> <p>Primitive <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span> contain a large array of organic compounds dominated by insoluble organic matter (IOM). A striking feature of this IOM is the systematic enrichment in deuterium compared with the solar hydrogen reservoir. This enrichment has been taken as a sign of low-temperature ion-molecule or gas-grain reactions. However, the extent to which Solar System processes, especially ionizing radiation, can affect D/H ratios is largely unknown. Here, we report the effects of electron irradiation on the hydrogen isotopic composition of organic precursors containing different functional groups. From an initial terrestrial composition, overall D-enrichments and differential intramolecular fractionations comparable with those measured in the Orgueil meteorite were induced. Therefore, ionizing radiation can quantitatively explain the deuteration of organics in some <span class="hlt">carbonaceous</span> <span class="hlt">chondrites</span>. For these meteorites, the precursors of the IOM may have had the same isotopic composition as the main water reservoirs of the inner Solar System. PMID:26461170</p>