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Sample records for semarkona ordinary chondrite

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

    Science.gov (United States)

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

    2005-01-01

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

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

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

    2008-01-01

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

  3. Metallic copper in ordinary chondrites

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    Rubin, Alan E.

    1994-01-01

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

  4. Shock metamorphism of ordinary chondrites

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

    1991-01-01

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

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

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

    2000-01-01

    We present the first detailed study of a population of texturally distinct chondrules previously described by Kurat (1969), Christophe Michel-Levy (1976), and Skinner et al. (1989) that are sharply depleted in alkalis and Al in their outer portions. These 'bleached' chondrules, which are exclusively radial pyroxene and cryptocrystalline in texture, have porous outer zones where mesostasis has been lost. Bleached chondrules are present in all type 3 ordinary chondrites and are present in lower abundances in types 4-6. They are most abundant in the L and LL groups, apparently less common in H chondrites, and absent in enstatite chondrites. We used x-ray mapping and traditional electron microprobe techniques to characterize bleached chondrules in a cross section of ordinary chondrites. We studied bleached chondrules from Semarkona by ion microprobe for trace elements and H isotopes, and by transmission electron microscopy. Chondrule bleaching was the result of low-temperature alteration by aqueous fluids flowing through fine-grained chondrite matrix prior to thermal metamorphism. During aqueous alteration, interstitial glass dissolved and was partially replaced by phyllosilicates, troilite was altered to pentlandite, but pyroxene was completely unaffected. Calcium-rich zones formed at the inner margins of the bleached zones, either as the result of the early stages of metamorphism or because of fluid-chondrule reaction. The mineralogy of bleached chondrules is extremely sensitive to thermal metamorphism in type 3 ordinary chondrites, and bleached zones provide a favorable location for the growth of metamorphic minerals in higher petrologic types. The ubiquitous presence of bleached chondrules in ordinary chondrites implies that they all experienced aqueous alteration early in their asteroidal histories, but there is no relationship between the degree of alteration and metamorphic grade. A correlation between the oxidation state of chondrite groups and their degree of

  6. Ubiquitous brecciation after metamorphism in equilibrated ordinary chondrites

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    Scott, E. R. D.; Lusby, D.; Keil, K.

    1985-01-01

    Ten objects with aberrant Fe/(Fe + Mg) ratios have been found in apparently unbrecciated types 4-6 H and L chondrites. Since the Fe/(Fe + Mg) ratios of these objects are incompatible with the metamorphic history of the host chondrites, it is concluded that a high proportion of ordinary chondrites are breccias that were lithified after peak metamorphism. This is consistent with the results of Scott (1984), who concluded that most type three ordinary chondrites are breccias of materials with diverse thermal histories, even though they do not show prominent brecciation. It is found that the classification scheme of Van Schmus and Wood (1967) does not identify chondrites with similar thermal histories; the petrologic type of a chondrite is only a measure of the average thermal history of its ingredients. Chondrite and achondrite breccias are also compared in order to understand how brecciation of chondrites after metamorphism is so well camouflaged.

  7. Post-metamorphic brecciation in type 3 ordinary chondrites

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

    1993-01-01

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

  8. Carbon in weathered ordinary chondrites from Roosevelt County

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    Ash, R. D.; Pillinger, C. T.

    1993-03-01

    A suite of Roosevelt County ordinary chondrites of known terrestrial age have been analyzed for carbon content and isotopic composition. Initial results indicate that significant carbon contamination is evident only in samples with a terrestrial age greater than 40 ka. These samples are of weathering grade D and E and contain three times more carbon than the less weathered samples. The soil in which they were preserved has a carbon content of ca. 1.5 percent. Over 200 meteorites have been recovered from a series of soil depleted areas of New Mexico and West Texas. Most have been recovered from blowouts near Clovis in Roosevelt County (RC) on the high plains of New Mexico. The mineralogical and petrologic Al effects of weathering upon these samples have been studied previously and show that the degree of weathering is largely depend ant upon the terrestrial residence time. The study was undertaken to determine the effects of prolonged exposure to the soil and climate of Roosevelt County upon ordinary chondrites in the hope that this will enable a better understanding of the problems associated with the collection of meteoritic falls. A suite of ten grade 4 to 6 H, L, and LL ordinary chondrites were analyzed for carbon content and isotopic composition.

  9. Metallographic cooling rates of L-group ordinary chondrites

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    Bennett, Marvin E.; Mcsween, Harry Y., Jr.

    1993-01-01

    Shock metamorphism appears to be a ubiquitous feature in L-group ordinary chondrites. Brecciation and heterogeneous melting obscure much of the early history of this meteorite group and have caused confusion as to whether L chondrites have undergone thermal metamorphism within onion-shell or rubble-pile parent bodies. Employing the most recent shock criteria, we have examined 55 Antarctic and 24 non-Antarctic L chondrites in order to identify those which have been least affected by post-accretional shock. Six low-shock samples (those with shock grade less than S4) of petrographic types L3-L5 were selected from both populations and metallographic cooling rates were obtained following the technique of Willis and Goldstein. All non-Antarctic L6 chondrites inspected were too heavily shocked to be included in this group. However, 4 shocked L6 chondrites were analyzed in order to determine what effects shock may impose on metallographic cooling rates. Metallographic cooling rates were derived by analyzing the cores of taenite grains and then measuring the distance to the nearest grain edge. Taenites were identified using backscatter imaging on a Cameca SX-50 electron microprobe. Using backscatter we were able to locate homogeneous, rust-free, nearly spherical grains. M-shaped profiles taken from grain traverses were also used to help locate the central portions of selected grains. All points which contained phosphorus above detection limits were discarded. Plots of cooling-rate data are summarized and data from the high-shock samples are presented. The lack of coherency of cooling rates for individual samples is indicative of heterogeneous cooling following shock. The data confirms the statement expressed by numerous workers that extreme care must be taken when selecting samples of L chondrites for cooling-rate studies. Data for the 6 non-Antarctic low-shock samples are also presented. The samples display a general trend in cooling rates. The lowest metamorphic grade

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

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

    1992-07-01

    that the vapor was pure H2O, the water:rock weight ratio required to account for the observed Fe oxidation was very modest, less than 3o/oo. However, the presence of even minor amounts of a fluid attending metamorphism has important implications for the interpretation of chemical and isotopic patterns in ordinary chondrites. For example, this vapor may have acted as a carrier gas to facilitate redistribution of volatile trace elements during metamorphism (Sugiura et al., 1984). Open-system metamorphism may also explain oxygen isotopic patterns seen in the data of Clayton et al. (1991). This pattern could have resulted from varying exchange with an isotopically light vapor at different temperatures, or with a vapor whose isotopic composition evolved as it permeated through the parent bodies. References: Alexander C.M. et al. (1989) Geochim. Cosmochim. Acta 53, 3045-3057. Brett R. and Sato M. (1984) Geochim. Cosmochim. Acta 48, 111-120. Clayton R.N. et al. (1991) Geochim. Cosmochim. Acta 55, 2317-2337. Ringwood A.E. (1965) Nature 207, 701-704. Rubin A.E. et al. (1988) In Meteorites and the Early Solar System (eds. J.F. Kerridge and M.S. Matthews), pp. 488-511. Univ. Arizona Press, Tucson, AZ. Sugiura N. et al. (1984) J. Geophys. Res. 89, B641-644. Williams R.J. (1971) Geochim. Cosmochim. Acta 35, 407-411.

  11. The ungrouped chondrite El Médano 301 and its comparison with other reduced ordinary chondrites

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    Pourkhorsandi, Hamed; Gattacceca, Jérôme; Devouard, Bertrand; D'Orazio, Massimo; Rochette, Pierre; Beck, Pierre; Sonzogni, Corinne; Valenzuela, Millarca

    2017-12-01

    El Médano 301 (EM 301) is an ungrouped chondrite with overall texture and trace-element distribution similar to those of ordinary chondrites (OCs), but with silicate (olivine and low-Ca pyroxene) compositions that are more reduced than those in OCs, with average olivine and low-Ca pyroxene of Fa3.9±0.3 and Fs12.8±4.9, respectively. These values are far lower than the values for OCs and even for chondrites designed as ;reduced; chondrites. Low-Ca pyroxene is the dominant mineral phase and shows zoning with higher MgO contents along the crystal rims and cracks (reverse zoning). The Co content of kamacite is also much lower than the concentrations observed in OCs (below detection limit of 0.18 wt% versus 0.44-37 wt%). Oxygen isotopic composition is Δ17O = +0.79,+0.78‰ and slightly different from that of OCs. The lower modal olivine/pyroxene ratio, different Infrared (IR) spectra, lower Co content of kamacite, lower mean FeO contents of olivine and pyroxene, different kamacite texture, and different oxygen-isotopic composition show that EM 301 does not belong to a known OC group. EM 301 shows similarities with chondritic clasts in Cumberland Falls aubrite, and with Northwest Africa 7135 (NWA 7135) and Acfer 370 ungrouped chondrites. However, dissimilar to NWA 7135 and the clasts, it does not contain highly reduced mineral phases like daubréelite. Our observations suggest the formation of EM 301 in a nebular region compositionally similar to OCs but with a different redox state, with oxygen fugacity (ƒO2) in this region lower than that of OCs and higher than that of enstatite chondrites condensation region. A second, possibly nebular, phase of reduction by the production of reducing gas phases (e.g., C-rich) could be responsible for the subsequent reduction of the primary material and the occurrence of reverse zoning in the low-Ca pyroxene and lower average Fa/Fs ratio. Based on the IR spectra of EM 301 we suggest the possibility that the parent body of this

  12. Metamorphism and partial melting of ordinary chondrites: Calculated phase equilibria

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    Johnson, T. E.; Benedix, G. K.; Bland, P. A.

    2016-01-01

    Constraining the metamorphic pressures (P) and temperatures (T) recorded by meteorites is key to understanding the size and thermal history of their asteroid parent bodies. New thermodynamic models calibrated to very low P for minerals and melt in terrestrial mantle peridotite permit quantitative investigation of high-T metamorphism in ordinary chondrites using phase equilibria modelling. Isochemical P-T phase diagrams based on the average composition of H, L and LL chondrite falls and contoured for the composition and abundance of olivine, ortho- and clinopyroxene, plagioclase and chromite provide a good match with values measured in so-called equilibrated (petrologic type 4-6) samples. Some compositional variables, in particular Al in orthopyroxene and Na in clinopyroxene, exhibit a strong pressure dependence when considered over a range of several kilobars, providing a means of recognising meteorites derived from the cores of asteroids with radii of several hundred kilometres, if such bodies existed at that time. At the low pressures (phase diagrams predict the onset of partial melting at 1050-1100 °C by incongruent reactions consuming plagioclase, clinopyroxene and orthopyroxene, whose compositions change abruptly as melting proceeds. These predictions match natural observations well and support the view that type 7 chondrites represent a suprasolidus continuation of the established petrologic types at the extremes of thermal metamorphism. The results suggest phase equilibria modelling has potential as a powerful quantitative tool in investigating, for example, progressive oxidation during metamorphism, the degree of melting and melt loss or accumulation required to produce the spectrum of differentiated meteorites, and whether the onion shell or rubble pile model best explains the metamorphic evolution of asteroid parent bodies in the early solar system.

  13. Shock veins in the Sahara 02500 ordinary chondrite

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    Owocki, Krzysztof; Muszyński, Andrzej

    2012-08-01

    A specimen of the Sahara 02500 ordinary chondrite contains shock-produced veins consisting of recrystallised fine-grained pyroxenes that include small droplets of Ni-rich metal. Non-melted olivines and pyroxenes show planar deformations filled by shock-melted and -polluted metal and troilite. Shock-melted feldspathic glass is present close to the shock veins. Geothermometric estimations indicate that the meteorite locally experienced moderate shock metamorphism with a minimum local peak temperature above 1400°C, resulting in partial melting of Ca-poor pyroxene and full melting of feldspars, metal and sulphides. The mineral assemblage in the shock veins suggests a pressure during melt recrystallisation below 10 GPa.

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

    Energy Technology Data Exchange (ETDEWEB)

    Troiano, Julianne; Rumble III, Douglas; Rivers, Mark L.; Friedrich, Jon M. (CIW); (UC); (Fordham)

    2011-11-17

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

  15. A unique type 3 ordinary chondrite containing graphite-magnetite aggregates - Allan Hills A77011

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

    1982-01-01

    ALHA 77011, which is the object of study in the present investigation, is a chondrite of the 1977 meteorite collection from Allan Hills, Antarctica. It contains an opaque and recrystallized silicate matrix (Huss matrix) and numerous aggregates consisting of micron- and submicron-sized graphite and magnetite. It is pointed out that no abundant graphite-magnetite aggregates could be observed in other type 3 ordinary chondrites, except for Sharps. Attention is given to the results of a modal analysis, relations between ALHA 77011 and other type 3 ordinary chondrites, and the association of graphite-magnetite and metallic Fe, Ni. The discovery of graphite-magnetite aggregates in type 3 ordinary chondrites is found to suggest that this material may have been an important component in the formation of ordinary chondrites.

  16. The Correo and Suwanee Spring meteorites - Two new ordinary chondrite finds

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    Rubin, A. E.; Taylor, G. J.; Keil, K.; Nelson, G. J.

    1981-03-01

    Two new ordinary chondrites were found about 40 km west of Albuquerque, New Mexico. Correo is an H4 chondrite with distinct chondrules and major olivine (Fo 81.4), orthopyroxene (En 82.3) and plagioclase (An 12). Suwanee Spring is an L5 chondrite with few distinct chondrules and a highly recrystallized matrix. Major minerals are olivine (Fo 75.4), orthopyroxene (En 77.7) and plagioclase (An 9). The metallic Ni-Fe phases of both meteorites are typical of slowly cooled ordinary chondrites.

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

    National Research Council Canada - National Science Library

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

    2014-01-01

    .... We present a data set of magnetic hysteresis properties of 91 ordinary chondrite falls. We show that hysteresis properties are distinctive of individual meteorites while homogeneous among meteorite subsamples...

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

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

    2014-04-01

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

  19. Phosphate and feldspar mineralogy of equilibrated L chondrites: The record of metasomatism during metamorphism in ordinary chondrite parent bodies

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    Lewis, Jonathan A.; Jones, Rhian H.

    2016-10-01

    In ordinary chondrites (OCs), phosphates and feldspar are secondary minerals known to be the products of parent-body metamorphism. Both minerals provide evidence that metasomatic fluids played a role during metamorphism. We studied the petrology and chemistry of phosphates and feldspar in petrologic type 4-6 L chondrites, to examine the role of metasomatic fluids, and to compare metamorphic conditions across all three OC groups. Apatite in L chondrites is Cl-rich, similar to H chondrites, whereas apatite in LL chondrites has lower Cl/F ratios. Merrillite has similar compositions among the three chondrite groups. Feldspar in L chondrites shows a similar equilibration trend to LL chondrites, from a wide range of plagioclase compositions in petrologic type 4 to a homogeneous albitic composition in type 6. This contrasts with H chondrites which have homogeneous albitic plagioclase in petrologic types 4-6. Alkali- and halogen-rich and likely hydrous metasomatic fluids acted during prograde metamorphism on OC parent bodies, resulting in albitization reactions and development of phosphate minerals. Fluid compositions transitioned to a more anhydrous, Cl-rich composition after the asteroid began to cool. Differences in secondary minerals between H and L, LL chondrites can be explained by differences in fluid abundance, duration, or timing of fluid release. Phosphate minerals in the regolith breccia, Kendleton, show lithology-dependent apatite compositions. Bulk Cl/F ratios for OCs inferred from apatite compositions are higher than measured bulk chondrite values, suggesting that bulk F abundances are overestimated and that bulk Cl/F ratios in OCs are similar to CI.

  20. Mössbauer spectroscopy of H, L and LL ordinary chondrites

    Energy Technology Data Exchange (ETDEWEB)

    Maksimova, A. A.; Oshtrakh, M. I., E-mail: oshtrakh@gmail.com; Petrova, E. V.; Grokhovsky, V. I.; Semionkin, V. A. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation)

    2016-12-15

    Fifteen fragments of H, L and LL ordinary chondrites were studied using Mössbauer spectroscopy with a high velocity resolution at 295 K. A new approach to fit troilite magnetic sextet using simulation of the full static Hamiltonian was applied that decreased spectra misfits. This approach permitted to obtain more correct and reliable parameters for the minor spectral components. Small variations in the {sup 57}Fe hyperfine parameters were revealed for the M1 and M2 sites in both olivine and orthopyroxene as well as for α-Fe(Ni, Co), α{sub 2}-Fe(Ni, Co) and γ-Fe(Ni, Co) phases in different ordinary chondrites. Some Mössbauer parameters showed the possibility to distinguish ordinary chondrites from H, L and LL groups that may be useful for their systematics.

  1. Shock-darkening in ordinary chondrites: Modeling of the pressure-temperature conditions

    Science.gov (United States)

    Moreau, J.; Kohout, T.; Wünnemann, K.

    2017-09-01

    Shock-darkening in ordinary chondrites is the melting of iron sulfides and metals into a network of veins. It leads to optical darkening and makes asteroid classification more difficult. In such cases, S-type asteroids (chondritic silicate composition) spectra look like C-type asteroids (associated with carbonacaeous chondrites). Using the shock physics code iSALE (Wünnemann et al. 2008) we determined the shock-darkening pressure range to be 40-50 GPa for the melting of iron sulfides. Apart from our results, this work brings a new understanding of shock waves interactions in heterogeneous medium and in modeling of shock metamorphism.

  2. Thermal and shock metamorphism of the sixiangkou ordinary chondrite

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    Ding, M. W.; Zhang, A. C.; Hsu, W. B.

    2008-01-01

    The Sixiangkou meteorite is a heavily shocked chondrite that contains numerous shock-induced melt veins of various widths. This paper focuses on the petrography and mineralogy of the host portion and shock veins of Sixiangkou. This meteorite contains relict chondrules with obscure structures and shapes. We calculate the peak equilibration temperature (891±36°C) recorded in the Sixiangkou L6 chondrite using the two-pyroxene geothermometer. The thermal metamorphic features of Sixiangkou are in accordance with the petrologic type 6. Olivine in the host portion of the chondrite shows obvious undulatory extinction and planar deformation features. Abundant maskelynite occurs in the chondrite. The shock veins contain numerous coarse-grained ringwoodite, majorite, and fine-grained high-pressure mineral assemblages. On the basis of these observations, Sixiangkou can be graded as S6 on the shock metamorphism scale. And it can also be inferred that the peak pressure which melt veins experienced is about 20GPa---24GPa and the temperature is higher than 2000°C. Merrilite and chromite in the shock veins are possibly transformed back from their high-pressure to low-pressure phases during the prolonged shock event Sixiangkou experienced.

  3. Discovery of Purple-Blue Ringwoodite Within Shock Veins of an LL6 Ordinary Chondrite from Northwest Africa

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    Bischoff, A.

    2002-03-01

    The purple-blue, mainly in L6 chondrites occurring high-pressure polymorph of olivine is known since many years and named ringwoodite. The Saharan LL6 ordinary chondrite contains this phase. This is the first discovery of ringwoodite in an LL-chondrite.

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

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

    1981-01-01

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

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

    Science.gov (United States)

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

    1993-01-01

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

  6. Hysteresis properties of ordinary chondrites and implications for their thermal history

    Science.gov (United States)

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

    2013-12-01

    We present a large dataset of magnetic hysteresis properties of ordinary chondrite falls. We show that hysteresis properties are distinctive of individual meteorites while homogeneous among meteorite subsamples. Except for the most primitive chondrites, these properties can be explained by a mixture of multidomain kamacite and tetrataenite (both in the cloudy zone and as larger grains in plessite and in the rim of zoned taenite). Kamacite dominates the induced magnetism whereas tetrataenite dominates the remanent magnetism, in agreement with previous microscopic magnetic observations. Type 5 and 6 chondrites have higher tetrataenite content than type 4 chondrites, suggesting they have lower cooling rates at least in the 650-450 °C interval, consistent with an onion-shell model. In equilibrated chondrites, shock-related transient heating events above ~500 °C result in the disordering of tetrataenite and associated drastic change in magnetic properties. As a good indicator of the amount of tetrataenite, hysteresis properties are a very sensitive proxy of the thermal history of ordinary chondrites, revealing low cooling rates during thermal metamorphism, and high cooling rates following shock reheating or excavation after thermal metamorphism.

  7. TEM Examination of Shock Veins in Ordinary Chondrites

    Science.gov (United States)

    Lingemann, C. M.; Langenhorst, F.; Stoffler, D.

    1995-09-01

    Introduction: As part of a research project on shock metamorphism of chondrites [1] we studied shock veins in different L-chondrites to understand their formation conditions. These thin shock veins (>20 micrometers thickness) have been found in the meteorites L5-6-Acfer 040, L6-Coorara, L6-Johnson City and L6-Tenham and were studied in detail by analytical transmission electron microscopy (ATEM). Texture. Shock veins consist of a fine-grained opaque matrix with embedded large fragments of the host chondrite. High-pressure polymorphs of olivine (ringwoodite and wadsleyite) and enstatite (majorite), which are clear indicators of strong shock metamorphism [1], are present in both matrix and fragments. In the matrix, majorite and, to a minor extent, ringwoodite coexist with globules of Fe-Ni alloy and troilite (ringwoodite and majorite occur as polycrystalline aggregates of tiny crystals (Ringwoodite shows generally a high density of stacking faults parallel to 110 planes. These stacking faults are interpreted as growth defects due to rapid cooling [2]. Majorite is defect-free. Chemistry. Ringwoodite in fragments is chemically less homogeneous and tends to a higher FeO-content than olivine in the host chondrite [3, 4]. A tendency to chemical heterogeneity has also been detected for majorite in fragments. The composition of the majorite in the matrix is distinctly heterogeneous and differs systematically from that of the enstatite, because it shows a distinct enrichment in Al, Mg, Ca, Na and a significant depletion in Si, Mn and especially in Fe, which is up to 50% lower than in the primary enstatite. Discussion. Chemical heterogeneity and small grain sizes of high-pressure phases as well as presence of Fe-Ni alloy and troilite in the form of globules indicates that shock veins represent quenched melts. The high-pressure phases are interpreted as crystallization products of these melts. The localized temperature excursions result probably from friction of the meteoritic

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

    Science.gov (United States)

    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.

  9. Unequilibrated ordinary chondrites - A tentative subclassification based on volatile-element content

    Science.gov (United States)

    Anders, E.; Zadnik, M. G.

    1985-01-01

    In view of the lack of correlation sometimes encountered between the volatile content and metamorphism measures of primitiveness for unequilibrated ordinary chondrites (UOCs), a tentative classification scheme is developed which is based on volatile content and complements the Sears et al. (1980) scheme based on metamorphism. The classification is based primarily on C and Xe, which are not significantly affected by shock-induced reheating. It is noted that novel clues to the formation of chondrites may be derivable from Xe and C; their concentrations in UOCs vary by a factor greater than 5, yet the Xe/C ratio remains nearly constant at 0.0034 of the solar system ratio.

  10. Phosphate minerals in LL chondrites: A record of the action of fluids during metamorphism on ordinary chondrite parent bodies

    Science.gov (United States)

    Jones, Rhian H.; McCubbin, Francis M.; Dreeland, Linda; Guan, Yunbin; Burger, Paul V.; Shearer, Charles K.

    2014-05-01

    Ordinary chondrites contain two phosphate minerals, merrillite and chlorapatite, both of which are secondary minerals that developed in response to metamorphism on the chondrite parent bodies. We have studied the phosphate mineralogy of four LL chondrites, of petrologic types 3.9-6, in order to determine the petrogenesis of the two minerals and interpret the conditions under which they formed. Characterization of merrillite and apatite includes textural observations, mineral compositions determined by electron probe microanalysis, and ion microprobe analyses of trace element and volatile anion elemental abundances. Initial formation of phosphate minerals during mild metamorphism, to petrologic type 4 conditions, resulted in oxidation of P that was originally incorporated in metal, and growth of merrillite as inclusions within metal grains. Subsequent development of both phosphate minerals occurred in response to diffusional equilibration, possible precipitation from fluids as well as replacement reactions resulting from interactions with fluids. Porosity and vein-filling textures in both merrillite and chlorapatite, as well as textures indicating replacement of merrillite by chlorapatite, support a model in which fluid played a significant role and suggest an interface-coupled dissolution-reprecipitation mechanism during metasomatism. Some associations of phosphate minerals with chromite-plagioclase assemblages suggest that phosphate minerals could also be related to impact processes, either as precipitation from an impact melt or as a result of interactions with a fluid or vapor derived from an impact melt. Fluid compositions may have been water-bearing initially, at low temperatures of metamorphism, but later evolved to become halogen-rich and very dry. Late-stage halogen-rich fluids that dominated during cooling of LL chondrite material may have been derived from vaporization of partial melts in the interior of the parent body. Overall, the LL chondrite parent

  11. Phosphate control on the Th/U variations in ordinary chondrites: Improving solar system abundances

    Science.gov (United States)

    Goreva, J. S.; Burnett, D. S.

    2001-01-01

    Isotope dilution thorium and uranium analyses by inductively-coupled plasma mass spectrometry of 12 samples of Harleton (L6) show a much larger scatter than was previously observed in equilibrated ordinary chondrites. Th/U linearly correlates with 1/U in Harleton and in the total equilibrated ordinary chondrite data set as well. Such a correlation suggests a two component mixture and this trend can be quantitatively modeled as reflecting variations in the mixing ratio between two phosphate phases: chlorapatite and merrillite. The major effect is due to apatite variations, which strongly control the whole rock U concentrations. Phosphorous variations will tend to destroy the Th/U vs. 1/U correlation, and measured P concentrations on exactly the same samples as U and Th show a factor of 3 range. It appears that the P variations are compensated by inverse variations in U (a dilution effect) to preserve the Th/U vs. 1/U correlation. Because variations in whole rock Th/U are consequences of phosphate sampling, a weighted average of high accuracy Th/U measurements in equilibrated ordinary chondrites should converge to a significantly improved average solar system Th/U. Our best estimate of this ratio is 3.53 with ?mean = 0.10.

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

    Science.gov (United States)

    Fukai, Ryota; Yokoyama, Tetsuya

    2017-09-01

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

  13. A new LL3 chondrite, Allan Hills A79003, and observations on matrices in ordinary chondrites

    Science.gov (United States)

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

    1982-01-01

    Allan Hills A79003 is an LL3 chondrite with a petrologic subtype of 3.4 + or - 0.2. Contrary to previous suggestions, it is not paired with other Allan Hills specimens. It contains haxonite, (Fe,Ni)23C6; shock-melted, 'fizzed' metal-troilite intergrowths; and translucent, glassy-looking Huss matrix (fine-grained, Fe-rich silicate matrix), in addition to the normal opaque and recrystallized varieties of Huss matrix. Some chondrules are partly coated with opaque matrix, others with translucent matrix. Translucent matrix is more uniform in composition and contains less S, CaO and FeO and more MgO than the opaque variety. Both kinds of matrix rimmed chondrules before consolidation of the meteorite.

  14. The use of SEM/EDS method in mineralogical analysis of ordinary chondritic meteorite

    Directory of Open Access Journals (Sweden)

    Breda Mirtič

    2009-12-01

    Full Text Available The aim of this study was to evaluate the potential of scanning electron microscopy coupled with energy dispersiveX-ray spectroscopy (SEM/EDS for determination of mineral phases according to their stoichiometry and assessment of mineral composition of ordinary chondritic meteorite. For the purposes of this study, H3 type ordinary chondritic meteorite Abbott was selected. SEM/EDS allows identification and characterisation of mineralphases, whose size is below the resolution of an optical microscope. Mineral phases in chondrules and interstitial matrix were located in backscattered electron (BSE mode and were assessed from atomic proportions of constituent elements, obtained by the EDS analysis. SEM/EDS analyses of mineral phases showed that Abbott meteorite is characterised by Fe-rich (Fe, Ni-alloy kamacite, Fe-sulphide troilite or pyrrhotite, chromite, Mg-rich olivine, orthopyroxene bronzite or hypersthene, clinopyroxene Al-diopside, acid plagioclase oligoclase, accessory mineral chlorapatite and secondary minerals Fe-hydroxides (goethite or lepidocrocite. Results of semi-quantitative analyses confirmed that most of analysed mineralphases conform well to stoichiometric minerals with minor deviations of oxygen from stoichiometric proportions. Comparison between mineral phases in chondrules and interstitial matrix was also performed, however it showed no significant differences in elemental composition.Differences in chemical composition between minerals in interstitial matrix and chondrules are sometimes too small to be discernedby the SEM/EDS, therefore knowledge of SEM/EDS capabilities is important for correct interpretation of chondrite formation.

  15. Postshock Annealing and Postannealing Shock in Equilibrated Ordinary Chondrites: Implications for the Thermal and Shock Histories of Chondritic Asteroids

    Science.gov (United States)

    Rubin, Alan E.

    2006-01-01

    In addition to shock effects in olivine, plagioclase, orthopyroxene and Ca-pyroxene, petrographic shock indicators in equilibrated ordinary chondrites (OC) include chromite veinlets, chromite-plagioclase assemblages, polycrystalline troilite, metallic Cu, irregularly shaped troilite grains within metallic Fe-Ni, rapidly solidified metal-sulfide intergrowths, martensite and various types of plessite, metal-sulfide veins, large metal and/or sulfide nodules, silicate melt veins, silicate darkening, low-Ca clinopyroxene, silicate melt pockets, and large regions of silicate melt. The presence of some of these indicators in every petrologic type-4 to -6 ordinary chondrite (OC) demonstrates that collisional events caused all equilibrated OC to reach shock stages S3-S6. Those type-4 to -6 OC that are classified as shock-stage S1 (on the basis of sharp optical extinction in olivine) underwent postshock annealing due to burial beneath materials heated by the impact event. Those type-4 to -6 OC that are classified S2 (on the basis of undulose extinction and lack of planar fractures in olivine) were shocked to stage S3-S6, annealed to stage S1 and then shocked again to stage S2. Some OC were probably shocked to stage 253 after annealing. It seems likely that many OC experienced multiple episodes of shock and annealing. Because 40Ar-39Ar chronological data indicate that MIL 99301 (LL6, Sl) was annealed approximately 4.26 Ga ago, presumably as a consequence of a major impact, it seems reasonable to suggest that other equilibrated S1 and S2 OC (which contain relict shock features) were also annealed by impacts. Because some type-6 S1 OC (e.g., Guarena, Kernouve, Portales Valley, all of which contain relict shock features) were annealed 4.44-4.45 Ga ago (during a period when impacts were prevalent and most OC were thermally metamorphosed), it follows that impact-induced annealing could have contributed significantly to OC thermal metamorphism.

  16. Itokawa dust particles: a direct link between S-type asteroids and ordinary chondrites.

    Science.gov (United States)

    Nakamura, Tomoki; Noguchi, Takaaki; Tanaka, Masahiko; Zolensky, Michael E; Kimura, Makoto; Tsuchiyama, Akira; Nakato, Aiko; Ogami, Toshihiro; Ishida, Hatsumi; Uesugi, Masayuki; Yada, Toru; Shirai, Kei; Fujimura, Akio; Okazaki, Ryuji; Sandford, Scott A; Ishibashi, Yukihiro; Abe, Masanao; Okada, Tatsuaki; Ueno, Munetaka; Mukai, Toshifumi; Yoshikawa, Makoto; Kawaguchi, Junichiro

    2011-08-26

    The Hayabusa spacecraft successfully recovered dust particles from the surface of near-Earth asteroid 25143 Itokawa. Synchrotron-radiation x-ray diffraction and transmission and scanning electron microscope analyses indicate that the mineralogy and mineral chemistry of the Itokawa dust particles are identical to those of thermally metamorphosed LL chondrites, consistent with spectroscopic observations made from Earth and by the Hayabusa spacecraft. Our results directly demonstrate that ordinary chondrites, the most abundant meteorites found on Earth, come from S-type asteroids. Mineral chemistry indicates that the majority of regolith surface particles suffered long-term thermal annealing and subsequent impact shock, suggesting that Itokawa is an asteroid made of reassembled pieces of the interior portions of a once larger asteroid.

  17. The natural thermoluminescence of meteorites. V - Ordinary chondrites at the Allan Hills ice fields

    Science.gov (United States)

    Benoit, Paul H.; Sears, Hazel; Sears, Derek W. G.

    1993-01-01

    Natural thermoluminescence (TL) data have been obtained for 167 ordinary chondrites from the ice fields in the vicinity of the Allan Hills in Victoria Land, Antarctica, in order to investigate their thermal and radiation history, pairing, terrestrial age, and concentration mechanisms. Natural TL values for meteorites from the Main ice field are fairly low, while the Farwestern field shows a spread with many values 30-80 krad, suggestive of less than 150-ka terrestrial ages. There appear to be trends in TL levels within individual ice fields which are suggestive of directions of ice movement at these sites during the period of meteorite concentration. These directions seem to be confirmed by the orientations of elongation preserved in meteorite pairing groups. The proportion of meteorites with very low natural TL levels at each field is comparable to that observed at the Lewis Cliff site and for modern non-Antarctic falls and is also similar to the fraction of small perihelia orbits calculated from fireball and fall observations. Induced TL data for meteorites from the Allan Hills confirm trends which show that a select group of H chondrites from the Antarctic experienced a different extraterrestrial thermal history to that of non-Antarctic H chondrites.

  18. Petrography and Mineralogy of 18 Newly Recovered Ordinary Chondrites in China

    Science.gov (United States)

    Li, S. L.

    2015-05-01

    Petrology and mineralogy of 18 newly recovered ordinary chondrites in China are reported in this paper. Fifteen meteorites were found in Xinjiang, among which 13 meteorites were found in the Lop Nur desert, and the other 2 meteorites were found in Kumtag and Aksai Chin, respectively. Three other meteorites are observed falls in Xining, Fuhe, and Dongyang, respectively. All meteorites are equilibrated ordinary chondrites with 8 H group and 10 L group meteorites. Their petrographic types vary from 4 to 6 in the L group meteorites, with most being type 5, while all H group meteorites are classified as type 5. The features of shock metamorphism of most meteorites are moderate though a few have features of ≥S4 stage. Most Lop Nur meteorites underwent intense weathering with only two of which have weathering degree of W1 and W2. Both Kumtag and Aksai Chin meteorite have a weathering degree of W2. The newly discovered tens of meteorites in the gobi deserts east to the Taklimakan Desert indicate that this region may become an important dense meteorite collection area in Eurasia.

  19. Na, K-Rich Rim Around a Chondrule in Unequilibrated Ordinary Chondrite Lew 86018 (L3.1)

    Science.gov (United States)

    Mishra, R. K.; Simon, J. I.; Ross, D. K.; Needham, A. W.; Messenger, S.; Keller, L. P.; Han, J.; Marhas, K. K.

    2015-01-01

    Ordinary chondrites represent the most abundant early Solar system extra-terrestrial (approximately 85% abundance) material available for laboratory studies and expectedly record the most extensive range of alterations effects from unmetamorphosed chondritic material to the highest temperatures of thermal metamorphism. The least metamorphosed chondrites belonging to petrologic type 3, the so called unequili-brated ordinary chondrites (UOCs), provide insights into alteration that happened during the primeval, ear-liest stage of Solar system formation. The higher grade petrologic types 4-6 ordinary chondrites on the other hand document up to near textural equilibrium (in type 6) extensive thermal metamorphism consisting of minerals and phases providing evidence of equilibration of heterogeneous mineral composition, solid-state recrystallization. Despite being the most abundant, the effect of alteration is less explicitly understood in ordinary chondrites (even less in UOCs) compared to other groups (e.g. CV, CO, CR). Additionally, the relationship between metasomatism (also referred as aqueous alteration or fluid-assisted metamorphism) and metamorphism (primarily thermal driven) has not been studied and alterations in the ordinary chondrites have been considered to have occurred in absence of fluids in general. Despite this conventional view, UOCs of lowest grades (3.0-3.2) show some evidence of low temperature (approximately 200 C), fluid assisted metamorphism in the form of the presence of phyllosilicates, ferroan olivine, and magnetites in their matrices and occasionally in chondrules. Here, we present petrographic and mineralogical studies of UOC, Lewis Hills (LEW) 86018 to further our understanding of the extent and relative importance of metasomatism and/or metamorphism in UOCs.

  20. Striking Graphite Bearing Clasts Found in Two Ordinary Chondrite Samples; NWA6169 and NWA8330

    Science.gov (United States)

    Johnson, Jessica M.; Zolensky, Michael E.; Chan, Queenie; Kring, David A.

    2015-01-01

    Meteorites play an integral role in understanding the history of the solar system. Not only can they contain some of the oldest material found in the solar system they also can contain material that is unique. Many lithologies are only found as foreign clasts within distinctly different host meteorites. In this investigation two foreign clasts within the meteorites, NWA6169 and NWA8330 were studied. The purpose of this investigation was to examine the mineralogy and petrography of the clasts within the samples. From there an identification and possible origin were to be inferred. NWA6169 is an unclassified ordinary chondrite that has a presumed petrologic type of L3. NWA8330 is a classified ordinary chondrite that has a petrologic type of LL3. Both meteorites were found to contain clasts that were similar; both modally were comprised of about 5% acicular graphite. Through SEM and Raman Spectroscopy it was found that they contained olivine, pyroxene, plagioclase, Fe-Ni sulfides, graphite, and metals. They were found to portray an igneous texture with relationships that suggest concurrent growth. Analytical microprobe results for NWA6169 revealed mineral compositions of Fa31-34, Fs23-83, and Ab7-85. For NWA8330 these were Fa28-32, Fs10-24, and Ab4-83. Only one similar material has been reported, in the L3 chondrite Krymka (Semenenko & Girich, 1995). The clast they described exhibited similar mineralogies including the unusual graphite. Krymka data displayed compositional values of Fa28.5-35.0 and Fs9-25.9. These ranges are fairly similar to that of NWA6169 and NWA8330. These samples may all be melt clasts, probably of impact origin. Two possibilities are (1) impact of a C-type asteroid onto the L chondrite parent asteroid, and (2) a piece of proto-earth ejected from the moon-forming collision event. These possibilities present abundant questions, and can be tested. The measurement of oxygen isotope compositions from the clasts should reveal the original source of the

  1. The Natural Thermoluminescence of Meteorites. Part 5; Ordinary Chondrites at the Allan Hills Ice Fields

    Science.gov (United States)

    Benoit, Paul H.; Sears, Hazel; Sears, Derek W. G.

    1993-01-01

    Natural thermoluminescence (TL) data have been obtained for 167 ordinary chondrites from the ice fields in the vicinity of the Allan Hills in Victoria Land, Antarctica, in order to investigate their thermal and radiation history, pairing, terrestrial age, and concentration mechanisms. Using fairly conservative criteria (including natural and induced TL, find location, and petrographic data), the 167 meteorite fragments are thought to represent a maximum of 129 separate meteorites. Natural TL values for meteorites from the Main ice field are fairly low (typically 5-30 krad, indicative of terrestrial ages of approx. 400 ka), while the Far western field shows a spread with many values 30-80 krad, suggestive of less then 150-ka terrestrial ages. There appear to be trends in TL levels within individual ice fields which are suggestive of directions of ice movement at these sites during the period of meteorite concentration. These directions seem to be confirmed by the orientations of elongation preserved in meteorite pairing groups. The proportion of meteorites with very low natural TL levels (less then 5 krad) at each field is comparable to that observed at the Lewis Cliff site and for modern non-Antarctic falls and is also similar to the fraction of small perihelia (less then 0.85 AU) orbits calculated from fireball and fall observations. Induced TL data for meteorites from the Allan Hills confirm trends observed for meteorites collected during the 1977/1978 and 1978/1979 field seasons which show that a select group of H chondrites from the Antarctic experienced a different extraterrestrial thermal history to that of non-Antarctic H chondrites.

  2. Mössbauer study of the Ordinary-Chondrite meteorite Thylacine Hole-001

    Science.gov (United States)

    Cadogan, J. M.; Devlin, E. J.

    2012-03-01

    The Thylacine Hole-001 meteorite was recovered from the Nullarbor Desert (Australia) in 1977 and is an Ordinary Chondrite, Group H4/5br, which has undergone moderate to severe (B/C) weathering. We have characterised the Fe-bearing phases in Thylacine Hole-001 by 57Fe Mössbauer Spectroscopy at 300 K, 100 K, 50 K and 4 K. The spectrum at 300 K is dominated by the paramagnetic doublets of Olivine, Pyroxene and a Ferric component which is most likely nanoparticulate Goethite. Magnetically split sextets due to Maghemite or Magnetite are also present, consistent with the relatively advanced terrrestrial age of 28,500 yrs The nanoparticulate Goethite component shows a blocked, magnetically split sextet at low temperatures. We also observe the effects of magnetic ordering of the Olivine and Pyroxene below 50 K.

  3. Spinel-Bearing, Al-Rich Chrondrules in the Unequilibrated Ordinary Chondrite NWA7402

    Science.gov (United States)

    Ross, D. K.; Simon, J. I.; Cato, M. J.

    2017-01-01

    Several Al-rich chondrules (ARCs) have been discovered in the unequilibrated ordinary chondrite NWA7402. Two of these three ARCs are spinel-bearing. Here we have characterized these unusual chondrules with respect to their mineralogy and bulk compositions. These objects will be targets for future O and Mg isotope analysis. NWA7402 is clearly unequilibrated, with wide ranges of olivine compositions in chondrules (Fo99-Fo70, excluding rims). Chromium-oxide contents in olivine, and Raman organic spectral parameters support the classification of this meteorite as petrologic type 3.1 [1]. NWA7402 is similar to, and could be paired with NWA5717, in that they both possess light and dark lithologies.

  4. An 57Fe Mössbauer study of the ordinary chondrite meteorite Lynch 001

    Science.gov (United States)

    Elewa, Nancy N.; Cadogan, J. M.

    2017-11-01

    The Lynch 001 meteorite was found in the Nullarbor Plain region of Western Australia in 1977. This meteorite is classified as an ordinary chondrite of the petrologic group L5/6 that has undergone `minor to moderate' terrestrial weathering. Here, we characterize the Fe-bearing phases in this chondrite using 57Fe Mössbauer spectroscopy carried out over the temperature range 13 K to room temperature (295 K). The paramagnetic doublets of olivine, pyroxene and a superparamagnetic ferric phase dominate the room temperature Mössbauer spectrum. On the basis of the room temperature quadrupole splitting of the olivine component, we estimate its composition to be Fa 30(5). Besides the paramagnetic ferric component, accounting for ˜15 % of the spectral area at room temperature, magnetically ordered ferric phases were also detected. The total relative proportion of the Fe 3+ components allows us to estimate the terrestrial age of Lynch 001 to be 6,500 ± 1,500 yr, consistent with the value of 6,700 ± 1,300 yr determined by 14C dating.

  5. Cosmogenic Records in 18 Ordinary Chondrites from the Dar Al Gani Region, Libya. 2; Radionclides

    Science.gov (United States)

    Welten, K. C.; Nishiizumi, K.; Finkel, R. C.; Hillegonds, D. J.; Jull, A. J. T.; Schultz, L.

    2003-01-01

    In the past decade more than 1000 meteorites have been recovered from the Dar al Gani (DaG) plateau in the Libyan part of the Sahara. The geological setting, meteorite pairings and density are described. So far, only a few terrestrial ages are known for DaG meteorites, e.g. 60+/- 20 kyr for the DaG 476 shergottite shower and 80+/- 20 kyr for the lunar meteorite DaG 262. However, from other desert areas, such as Oman, it is known that achondrites may survive much longer than chondritic meteorites, so the ages of these two achondrites may not be representative of the majority of the DaG meteorite collection, of which more than 90% are ordinary chondrites. In this work we report concentrations of the cosmogenic radionuclides, 14C (half-life = 5,730 yr), 41Ca (1.04x10 superscript 5 yr), Cl-36 (3.01x10 superscript 5 yr), Al-26 (7.05x10 superscript 5 yr) and 10Be (1.5x10 superscript 6 yr) to determine the terrestrial ages of DaG meteorites and constrain their pre-atmospheric size and exposure history.

  6. Ancient porosity preserved in ordinary chondrites: Examining shock and compaction on young asteroids

    Science.gov (United States)

    Friedrich, Jon M.; Rubin, Alan E.; Beard, Sky P.; Swindle, Timothy D.; Isachsen, Clark E.; Rivers, Mark L.; Macke, Robert J.

    2014-07-01

    We use a combination of 2D and 3D petrographic examination and 40Ar-39Ar analyses to examine the impact histories of a suite of seven ordinary chondrites (Baszkówka, Miller, NWA 2380, Mount Tazerzait, Sahara 98034, Tjerebon, and MIL 99301) that partially preserve their ancient, but postaccretionary, porosity ranging from 10 to 20%. We examine whether materials that seem to be only mildly processed (as their large intergranular pore spaces suggest) may have more complex shock histories. The ages determined for most of the seven OCs studied here indicate closure of the 40Ar-39Ar system after primary accretion, but during (Baszkówka) or shortly after (others) thermal metamorphism, with little subsequent heating. Exceptions include Sahara 98034 and MIL 99301, which were heated to some degree at later stages, but retain some evidence for the timing of thermal metamorphism in the 40Ar-39Ar system. Although each of these chondrites has olivine grains with sharp optical extinction (signaling an apparent shock stage of S1), normally indicative of an extremely mild impact history, all of the samples contain relict shock indicators. Given the high porosity and relatively low degree of compaction coupled with signs of shock and thermal annealing, it seems plausible that impacts into materials that were already hot may have produced the relict shock indicators. Initial heating could have resulted from prior collisions, the decay of 26Al, or both processes.

  7. An {sup 57}Fe Mössbauer study of the ordinary chondrite meteorite Lynch 001

    Energy Technology Data Exchange (ETDEWEB)

    Elewa, Nancy N., E-mail: nancy.elewa@student.unsw.edu.au; Cadogan, J. M. [The University of New South Wales at the Australian Defence Force Academy, School of Physical, Environmental and Mathematical Sciences (Australia)

    2017-11-15

    The Lynch 001 meteorite was found in the Nullarbor Plain region of Western Australia in 1977. This meteorite is classified as an ordinary chondrite of the petrologic group L5/6 that has undergone ‘minor to moderate’ terrestrial weathering. Here, we characterize the Fe-bearing phases in this chondrite using {sup 57}Fe Mössbauer spectroscopy carried out over the temperature range 13 K to room temperature (295 K). The paramagnetic doublets of olivine, pyroxene and a superparamagnetic ferric phase dominate the room temperature Mössbauer spectrum. On the basis of the room temperature quadrupole splitting of the olivine component, we estimate its composition to be Fa {sub 30(5)}. Besides the paramagnetic ferric component, accounting for ∼15 % of the spectral area at room temperature, magnetically ordered ferric phases were also detected. The total relative proportion of the Fe {sup 3+} components allows us to estimate the terrestrial age of Lynch 001 to be 6,500 ± 1,500 yr, consistent with the value of 6,700 ± 1,300 yr determined by {sup 14}C dating.

  8. Late Eocene 3He and Ir anomalies associated with ordinary chondritic spinels

    Science.gov (United States)

    Boschi, Samuele; Schmitz, Birger; Heck, Philipp R.; Cronholm, Anders; Defouilloy, Céline; Kita, Noriko T.; Monechi, Simonetta; Montanari, Alessandro; Rout, Surya S.; Terfelt, Fredrik

    2017-05-01

    During the late Eocene there was an enigmatic enhancement in the flux of extraterrestrial material to Earth. Evidence comes from sedimentary 3He records indicating an increased flux of interplanetary dust during ca. 2 Myr, as well as two very large impact structures, Popigai (100 km diameter) and Chesapeake Bay (40-85 km), that formed within 10-20 kyr at the peak of the 3He delivery. The Massignano section in Italy has one of the best sedimentary records of these events, including a well-defined 3He record, an Ir-rich ejecta bed related to the Popigai impact event, and two smaller Ir anomalies. Recently we showed that the Popigai ejecta is associated with a significant enrichment of chromite grains (>63 μm) with an H-chondritic elemental composition (17 grains in 100 kg of rock). Most likely these grains are unmelted fragments from the impactor. Slightly higher up (ca. 20 cm) in the section, where a small Ir anomaly possibly related to the Chesapeake Bay impact has been measured, we found a weak enrichment in L-chondritic grains (8 grains in 208 kg of rock). Here we report an extended data set increasing the total amount of sediment dissolved in acid and searched for extraterrestrial chromite grains from 658 to 1168 kg. In altogether 760 kg of background sediment from 17 levels over 14 m of strata outside the interval corresponding to the Popigai and Chesapeake Bay impacts, we only found 2 extraterrestrial chromite grains. Both grains have L-chondritic compositions and were found in a 100 kg sample from the ca. 10.25 m level in the section where the second of the smaller Ir anomalies has been reported. A correlation appears to exist between Ir, 3He and chromite from ordinary chondrites. We also report oxygen three-isotope measurements of the extraterrestrial chromite grains associated with the Popigai ejecta and confirm an H-chondritic composition. The new results strengthen our scenario that the upper Eocene 3He and Ir enrichments originate from the asteroid belt

  9. Relationships among physical properties as indicators of high temperature deformation or post-shock thermal annealing in ordinary chondrites

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, Jon M.; Ruzicka, Alex; Macke, Robert J.; Thostenson, James O.; Rudolph, Rebecca A.; Rivers, Mark L.; Ebel, Denton S.

    2017-04-01

    Collisions and attendant shock compaction must have been important for the accretion and lithification of planetesimals, including the parent bodies of chondrites, but the conditions under which these occurred are not well constrained. A simple model for the compaction of chondrites predicts that shock intensity as recorded by shock stage should be related to porosity and grain fabric. To test this model, we studied sixteen ordinary chondrites of different groups (H, L, LL) using X-ray computed microtomography (μCT) to measure porosity and metal fabric, ideal gas pycnometry and 3D laser scanning to determine porosity, and optical microscopy (OM) to determine shock stage. These included a subsample of six chondrites previously studied using transmission electron microscopy (TEM) to characterize microstructures in olivine. Combining with previous data, results support the simple model in general, but not for chondrites with low shock-porosity-foliation (low-SPF chondrites). These include Kernouvé (H6), Portales Valley (H6/7), Butsura (H6), Park (L6), GRO 85209 (L6), Estacado (H6), MIL 99301 (LL6), Spade (H6), and Queen’s Mercy (H6), among others. The data for these meteorites are best explained by high ambient heat during or after shock. Low-SPF chondrites tend to have older 40Ar/39Ar ages (~4435–4526 Ma) than other, non-low-SPF type 6 chondrites in this study. We conclude that the H, L, and LL asteroids all were shock-compacted at an early stage while warm, with collisions occurring during metamorphic heating of the parent bodies. Results ultimately bear on whether chondrite parent bodies have internal structures more akin to a metamorphosed onion shell or metamorphosed rubble pile, and on the nature of accretion and lithification processes for planetesimals.

  10. Relationships among physical properties as indicators of high temperature deformation or post-shock thermal annealing in ordinary chondrites

    Science.gov (United States)

    Friedrich, Jon M.; Ruzicka, Alex; Macke, Robert J.; Thostenson, James O.; Rudolph, Rebecca A.; Rivers, Mark L.; Ebel, Denton S.

    2017-04-01

    Collisions and attendant shock compaction must have been important for the accretion and lithification of planetesimals, including the parent bodies of chondrites, but the conditions under which these occurred are not well constrained. A simple model for the compaction of chondrites predicts that shock intensity as recorded by shock stage should be related to porosity and grain fabric. To test this model, we studied sixteen ordinary chondrites of different groups (H, L, LL) using X-ray computed microtomography (μCT) to measure porosity and metal fabric, ideal gas pycnometry and 3D laser scanning to determine porosity, and optical microscopy (OM) to determine shock stage. These included a subsample of six chondrites previously studied using transmission electron microscopy (TEM) to characterize microstructures in olivine. Combining with previous data, results support the simple model in general, but not for chondrites with low shock-porosity-foliation (low-SPF chondrites). These include Kernouvé (H6), Portales Valley (H6/7), Butsura (H6), Park (L6), GRO 85209 (L6), Estacado (H6), MIL 99301 (LL6), Spade (H6), and Queen's Mercy (H6), among others. The data for these meteorites are best explained by high ambient heat during or after shock. Low-SPF chondrites tend to have older 40Ar/39Ar ages (∼4435-4526 Ma) than other, non-low-SPF type 6 chondrites in this study. We conclude that the H, L, and LL asteroids all were shock-compacted at an early stage while warm, with collisions occurring during metamorphic heating of the parent bodies. Results ultimately bear on whether chondrite parent bodies have internal structures more akin to a metamorphosed onion shell or metamorphosed rubble pile, and on the nature of accretion and lithification processes for planetesimals.

  11. Chromite-rich mafic silicate chondrules in ordinary chondrites: Formation by impact melting

    Science.gov (United States)

    Krot, Alexander N.; Rubin, Alan E.

    1993-01-01

    Chromium-rich chondrules constitute less than 0.1 percent of all ordinary chondrite (OC) chondrules and comprise three groups: chromian-spinel chondrules, chromian-spinel inclusions, and chromite-rich mafic silicate (CRMS) chondrules. Chromian-spinel chondrules (typically 100-300 microns in apparent diameter) exhibit granular, porphyritic and unusual textures and occur mainly in H chondrites. Their morphologies are distinct from the irregularly shaped chromian-spinel inclusions of similar mineralogy. Chromian-spinel chondrules and inclusions consist of grains of chromian-spinel embedded in plagioclase (Pl) or mesostasis of Pl composition. Many also contain accessory ilmenite (Ilm), high-Ca pyroxene (Px), merrillite (Mer), and rare olivine (Ol); some exhibit concentric mineral and chemical zoning. CRMS chondrules (300-1100 microns in apparent diameter) are generally larger than chromian-spinel chondrules and occur in all metamorphosed OC groups. Most CRMS chondrules are nearly spherical although a few are ellipsoidal with a/b aspect ratios ranging up to 1.7. Textures include cryptocrystalline, granular, radial, barred, and porphyritic varieties; some contain apparently relict grains. The chondrules consist of chromite (Chr), Ol and Pl, along with accessory Mer, troilite (Tr), metallic Fe-Ni (Met), Px and Ilm. The mesostasis in CRMS chondrules is nearly opaque in transmitted light; thus, they can be easily recognized in the optical microscope. Based on the similarity of mineralogy and chemistry between CRMS chondrules of different textures (opaque chromite-rich mesostasis, skeletal morphology of Ol grains, similar bulk compositions) we suggest that these chondrules form a genetically related population.

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

    Science.gov (United States)

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

    2011-01-01

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

  13. In situ60Fe-60Ni systematics of chondrules from unequilibrated ordinary chondrites

    Science.gov (United States)

    Telus, Myriam; Huss, Gary R.; Nagashima, Kazuhide; Ogliore, Ryan C.; Tachibana, Shogo

    2018-01-01

    The initial 60Fe/56Fe of chondrules from unequilibrated ordinary chondrites (UOCs) can potentially constrain the stellar source of short-lived radionuclides and develop the 60Fe-60Ni (t1/2 = 2.6 Ma) system for early solar system chronology. However, progress with the 60Fe-60Ni system has been hindered by discrepancies between initial ratios inferred from bulk and in situ Fe-Ni analyses. Telus et al. (2016) show that discrepancies between these different techniques stem from late-stage open-system Fe-Ni mobilization. Here, we report in situ analyses of the Fe-Ni isotopic composition of ferromagnesian silicates in chondrules from UOCs using the ion microprobe. Of the 24 chondrules analyzed for this study, a few chondrules have resolved excesses in 60Ni of up to 70‰; however, the correlations with Fe/Ni are weak. Although complications from Fe-Ni redistribution make it difficult to interpret the data, we show that the initial 60Fe/56Fe for UOC chondrules is between 5 × 10-8 and 3.0 × 10-7. This is consistent with a late supernova source for 60Fe, but self-enrichment of the molecular cloud is another possible mechanism for incorporating 60Fe in the solar system. Discrepancies between bulk and in situ analyses remain, but likely stem from late-stage open-system Fe-Ni mobilization.

  14. Petrology, mineralogy, porosity, and cosmic-ray exposure history of Huaxi ordinary chondrite

    Science.gov (United States)

    Li, Shijie; Wang, Shijie; Leya, Ingo; Li, Yang; Li, Xiongyao; Smith, Thomas

    2017-05-01

    A meteorite fall was heard and collected on July 13, 2010 at about 18:00 (local time) in the Shibanjing village of the Huaxi district of Guiyang, Guizhou province, China. The total mass of the fall is estimated to be at least 1.6 kg; some fragments are missing. The meteorite consists mainly of olivine, low-Ca pyroxene, high-Ca pyroxene, plagioclase, kamacite, taenite, and troilite. Minor phases include chromite and apatite. Various textural types of chondrules exist in this meteorite: most chondrule textures can be easily defined. The grain sizes of secondary plagioclase in this meteorite range from 2 to 50 μm. The chemical composition of olivine and low-Ca pyroxene are uniform; Fa in olivine and Fs in low-Ca pyroxene are, respectively, 19.6 ± 0.2 and 17.0 ± 0.3 (mole%). Huaxi has been classified as an H5 ordinary chondrite, with a shock grade S2, and weathering W0. The weak shock features, rare fractures, and the high porosity (17.6%) indicates that Huaxi is a less compacted meteorite. The preatmospheric radius of Huaxi is 11 cm, corresponding to 21 kg. The meteorite experienced a relatively short cosmic-ray exposure of about 1.6 ± 0.1 Ma. The 4He and 40Ar retention ages are older than 4.6 Ga implying that Huaxi did not degas after thermal metamorphism on its parent body.

  15. Micro-Raman of mineral phases in the strongly shocked Taiban ordinary chondrite: ringwoodite coloration

    Science.gov (United States)

    Acosta, T. E.; Scott, E. R. D.; Sharma, S. K. S.; Misra, A. K.

    2012-09-01

    High pressure polymorphs of major minerals are commonly found in shocked meteorites. During the formation evolution of the Solar System asteroids have collided with each other and with larger bodies triggering shock waves. The produced Meteorites show different shock effects depending on the peak pressures and temperatures, and duration of the collision events [5]. Taiban is a very strongly shocked, shock stage S6 ordinary L6 chondrite. It shows multiple veins of opaque shock melt forming a network of complex branches surrounding pockets of highly shock altered, mosaicized, relict or recrystalized silicates, and their high pressure polymorphs [4,5]. Micro-Raman spectroscopy has been used to provide univocal identification of minerals and glassy phases in meteorites as well as a tool to obtain additional information on structural and compositional variations inside mineral grains [7]. We studied the polished thin section UNM297 of Taiban meteorite with micro-Raman spectroscopy and Raman mapping to identify and characterize major and minor phases. Ringwoodite g-(Fe,Mg)2Si04 is the high-pressure polymorph of olivine with the spinel structure.

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

    Science.gov (United States)

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

    1994-01-01

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

  17. The {sup 57}Fe hyperfine interactions in the iron-bearing phases in some LL ordinary chondrites

    Energy Technology Data Exchange (ETDEWEB)

    Oshtrakh, M. I., E-mail: oshtrakh@gmail.com; Maksimova, A. A.; Grokhovsky, V. I.; Petrova, E. V.; Semionkin, V. A. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation)

    2016-12-15

    The study of several LL ordinary chondrites such as NWA 6286 LL6, NWA 7857 LL6 and Chelyabinsk LL5 fragments with different lithology was carried out using scanning electron microscopy with energy dispersion spectroscopy, X-ray diffraction and {sup 57}Fe Mössbauer spectroscopy with a high velocity resolution at 295 K. Small variations in the {sup 57}Fe hyperfine parameters were revealed for the M1 and M2 sites in olivine, orthopyroxene and clinopyroxene as well as for α-Fe(Ni, Co), α{sub 2}-Fe(Ni, Co) and γ-Fe(Ni, Co) phases, and for troilite in different samples of studied LL ordinary chondrites.

  18. Using the U-Pb system's dual decay scheme towards reconstructing the thermal histories and origins of ordinary chondrites (Invited)

    Science.gov (United States)

    Blackburn, T. J.; Elkins-Tanton, L. T.; Carlson, R. W.; Alexander, C. M.; Hourigan, J. K.

    2013-12-01

    Ordinary chondrites provide a record of planetary formation through the accretion of the Solar System's earliest forming solids. Despite the critical importance these samples have for understanding Solar System history, the origin of chondrites as well as the size and histories of their parent bodies remains unclear. The antiquity of chondrules permit chondrite accretion prior to the extinction of the 26Al short-lived radionuclide and the possibility of parent body melting and differentiation due to radioactive heating. Yet this antiquity and the overall abundance of chondrites has raised questions concerning the origin of chondrules and the conditions leading to the preservation of their primordial geochemical signatures, accretion textures and ancient inclusions. In short, if these bodies accreted early in the history of the solar system, how has this material avoided melting by radioactive heating? Different models for the size and structure of the chondrite parent bodies as well as for chondrule formation exist to explain how chondrites survive or avoid early radiogenic heating. Here we propose to evaluate these scenarios through comparison between modeled thermal histories and thermal histories reconstructed using U-Pb thermochronology of chondritic phosphates. Detailed thermal histories are reconstructed by exploiting the U-Pb system's dual decay scheme, where two parent isotopes, 238U and 235U, decay to two daughter isotopes 206Pb and 207Pb respectively. The difference in decay rates between parent isotopes imposes a time-variant parent and instantaneous daughter isotopic composition for any point in Solar System history. This new thermochronologic methodology works to capture this isotopic evolution using the variation in the time of Pb retention between both: 1) chondrites from different parent body depths or metamorphic grades, where variations in the timescale of cooling result from the thermal gradient within a conductively cooling body, and; 2

  19. Deformation and thermal histories of ordinary chondrites: Evidence for post-deformation annealing and syn-metamorphic shock

    Science.gov (United States)

    Ruzicka, Alex; Hugo, Richard; Hutson, Melinda

    2015-08-01

    We show that olivine microstructures in seven metamorphosed ordinary chondrites of different groups studied with optical and transmission electron microscopy can be used to evaluate the post-deformation cooling setting of the meteorites, and to discriminate between collisions affecting cold and warm parent bodies. The L6 chondrites Park (shock stage S1), Bruderheim (S4), Leedey (S4), and Morrow County (S5) were affected by variable shock deformation followed by relatively rapid cooling, and probably cooled as fragments liberated by impact in near-surface settings. In contrast, Kernouvé (H6 S1), Portales Valley (H6/7 S1), and MIL 99301 (LL6 S1) appear to have cooled slowly after shock, probably by deep burial in warm materials. In these chondrites, post-deformation annealing lowered apparent optical strain levels in olivine. Additionally, Kernouvé, Morrow County, Park, MIL 99301, and possibly Portales Valley, show evidence for having been deformed at an elevated temperature (⩾800-1000 °C). The high temperatures for Morrow County can be explained by dynamic heating during intense shock, but Kernouvé, Park, and MIL 99301 were probably shocked while the H, L and LL parent bodies were warm, during early, endogenically-driven thermal metamorphism. Thus, whereas the S4 and S5 chondrites experienced purely shock-induced heating and cooling, all the S1 chondrites examined show evidence for static heating consistent with either syn-metamorphic shock (Kernouvé, MIL 99301, Park), post-deformation burial in warm materials (Kernouvé, MIL 99301, Portales Valley), or both. The results show the pitfalls in relying on optical shock classification alone to infer an absence of shock and to construct cooling stratigraphy models for parent bodies. Moreover, they provide support for the idea that "secondary" metamorphic and "tertiary" shock processes overlapped in time shortly after the accretion of chondritic planetesimals, and that impacts into warm asteroidal bodies were

  20. A note on the Allan Hills A77278 unequilibrated ordinary chondrite

    Science.gov (United States)

    Mcsween, H. Y., Jr.; Wilkening, L. L.

    1980-01-01

    Petrographic measures of disequilibrium in the ALHA 77278 chondrite indicate that this meteorite is more equilibrated than its exceptionally high volatile element contents suggest. Based on its metal compositions, this meteorite should be classified as an LL3 rather than an L3 chondrite.

  1. Magnetic properties of the LL5 ordinary chondrite Chelyabinsk (fall of February 15, 2013)

    National Research Council Canada - National Science Library

    Bezaeva, Natalia S; Badyukov, Dmitry D; Nazarov, Mikhail A; Rochette, Pierre; Feinberg, Joshua M; Markov, Gennadiy P; Borschneck, Daniel; Demory, François; Gattacceca, Jérôme; Borisovskiy, Sergey E; Skripnik, Anna Ya

    2014-01-01

    Here we characterize the magnetic properties of the Chelyabinsk chondrite ( LL 5, S4, W0) and constrain the composition, concentration, grain size distribution, and mineral fabric of the meteorite's magnetic mineral assemblage...

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

    Science.gov (United States)

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

    2017-08-01

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

  3. Cosmic-ray exposure ages of the ordinary chondrites and their significance for parent body stratigraphy

    Science.gov (United States)

    Crabb, J.; Schultz, L.

    1981-01-01

    Improved exposure ages are derived for 201 H, 203 L, and 38 LL chondrites in an effort to understand the characteristics of the chondrite parent body. The Ne-21 exposure ages were calculated from literature values taking into account shielding differences, a trapped component and radiogenic He. The exposure age distributions show clear peaks at 4.5 and 20 million years for the H chondrites, while the Ls and LLs appear more as a continuous series of intermediate peaks which may be modeled by at least six peaks between 1 and 35 million years in the case of L chondrites. The observations that every petrological type occurs in each large peak and contain solar wind gases suggest that the parent bodies have been fragmented and reassembled into a megabreccia. The H meteorites are proposed to represent the surface layer of a body with a substantial, active regolith as indicated by the relatively high abundances of solar gases. The L chondrites, on the other hand, are attributed to a parent body that was fragmented by collision about 500 million years ago.

  4. LOW {sup 60}FE ABUNDANCE IN SEMARKONA AND SAHARA 99555

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Haolan; Dauphas, Nicolas, E-mail: haolantang@ucla.edu [Origins Lab, Department of the Geophysical Sciences and Enrico Fermi Institute, The University of Chicago, 5734 South Ellis Avenue, Chicago IL 60637 (United States)

    2015-03-20

    Iron-60 (t{sub 1/2} = 2.62 Myr) is a short-lived nuclide that can help constrain the astrophysical context of Solar System formation and date early Solar System events. A high abundance of {sup 60}Fe({sup 60}Fe/{sup 56}Fe ≈ 4 × 10{sup −7}) was reported by in situ techniques in some chondrules from the LL3.00 Semarkona meteorite, which was taken as evidence that a supernova exploded in the vicinity of the birthplace of the Sun. However, our previous multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) measurements of a wide range of meteoritic materials, including chondrules, showed that {sup 60}Fe was present in the early Solar System at a much lower level ({sup 60}Fe/{sup 56}Fe ≈ 10{sup −8}). The reason for the discrepancy is unknown but only two Semarkona chondrules were measured by MC-ICPMS and these had Fe/Ni ratios below ∼2× chondritic. Here, we show that the initial {sup 60}Fe/{sup 56}Fe ratio in Semarkona chondrules with Fe/Ni ratios up to ∼24× chondritic is (5.39 ± 3.27) × 10{sup −9}. We also establish the initial {sup 60}Fe/{sup 56}Fe ratio at the time of crystallization of the Sahara 99555 angrite, a chronological anchor, to be (1.97 ± 0.77) × 10{sup −9}. These results demonstrate that the initial abundance of {sup 60}Fe at Solar System birth was low, corresponding to an initial {sup 60}Fe/{sup 56}Fe ratio of (1.01 ± 0.27) × 10{sup −8}.

  5. An Oxygen Isotopic Link Between Rumuruti and Ordinary Chondrites from Oman: Evidence from the Chondrules in Dhofar 1671 (R3.6)

    Science.gov (United States)

    Ali, A.; Nasir, S. J.; Jabeen, I.

    2017-05-01

    A genetic link between Rumuruti and ordinary chondrites is revealed by the O-isotope compositions of the bulk chondrules in the Dhofar 1671, an R type find from Oman. The data from these chondrules connect the L6 type OCs recently found in Oman.

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

    Science.gov (United States)

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

    2017-08-01

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

  7. Investigation of the H7 ordinary chondrite, Watson 012: Implications for recognition and classification of Type 7 meteorites

    Science.gov (United States)

    Tait, Alastair W.; Tomkins, Andrew G.; Godel, Bélinda M.; Wilson, Siobhan A.; Hasalova, Pavlina

    2014-06-01

    Despite the fact that the number of officially classified meteorites is now over 45,000, we lack a clearly defined sequence of samples from a single parent body that records the entire range in metamorphic temperatures from pristine primitive meteorites up to the temperatures required for extensive silicate partial melting. Here, we conduct a detailed analysis of Watson 012, an H7 ordinary chondrite, to generate some clarity on the textural and chemical changes associated with equilibrium-based silicate partial melting in chondritic meteorites. To do this we compare the textures in the meteorite with those preserved in metamorphic contact aureoles on Earth. The most distinctive texture generated by the partial melting that affected Watson 012 is an extensively interconnected plagioclase network, which is clearly observable with a petrographic microscope. Enlarged metal-troilite grains are encapsulated at widenings in this plagioclase network, and this is clearly visible in reflected light. Together with these features, we define a series of other characteristics that can be used to more clearly classify chondritic meteorites as being of petrologic Type 7. To provide comprehensive evidence of silicate partial melting and strengthen the case for using simple petrographic observations to classify similar meteorites, we use high-resolution X-ray computed tomography to demonstrate that the plagioclase network has a high degree of interconnectedness and crystallised as large (cm-scale) skeletal crystals within an olivine-orthopyroxene-clinopyroxene framework, essentially pseudomorphing a melt network. Back-scattered electron imaging and element mapping are used to show that some of the clino- and orthopyroxene in Watson 012 also crystallised from silicate melt, and the order of crystallisation was orthopyroxene → clinopyroxene → plagioclase. X-ray diffraction data, supported by bulk geochemistry, are used to show that plagioclase and ortho- and clinopyroxene were

  8. In-situ X-ray CT results of damage evolution in L6 ordinary chondrite meteorites

    Energy Technology Data Exchange (ETDEWEB)

    Cuadra, Jefferson A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hazeli, Kavan [Univ. of Alabama, Huntsville, AL (United States); Ramesh, K. T. [Johns Hopkins Univ., Baltimore, MD (United States). Hopkins Extreme Materials Inst.; Martz, Harry [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Nondestructive Characterization Inst.

    2016-06-17

    These are slides about in-situ X-ray CT results of damage evolution in L6 ordinary chondrite meteorites. The following topics are covered: mechanical and thermal damage characterization, list of Grosvenor Mountain (GRO) meteorite samples, in-situ x-ray compression test setup, GRO-chipped reference at 0 N - existing cracks, GRO-chipped loaded at 1580 N, in-situ x-ray thermal fatigue test setup, GRO-B14 room temperature reference, GRO-B14 Cycle 47 at 200°C, GRO-B14 Cycle 47 at room temperature, conclusions from qualitative analysis, future work and next steps. Conclusions are the following: Both GRO-Chipped and GRO-B14 had existing voids and cracks within the volume. These sites with existing damage were selected for CT images from mechanically and thermally loaded scans since they are prone to damage initiation. The GRO-Chipped sample was loaded to 1580 N which resulted in a 14% compressive engineering strain, calculated using LVDT. Based on the CT cross sectional images, the GRO-B14 sample at 200°C has a thermal expansion of approximately 96 μm in height (i.e. ~1.6% engineering strain).

  9. Raman spectroscopic study of four Spanish shocked ordinary chondrites: Cañellas, Olmedilla de Alarcón, Reliegos and Olivenza.

    Science.gov (United States)

    Rull, F; Muñoz-Espadas, M J; Lunar, R; Martínez-Frías, J

    2010-07-13

    Shock metamorphism in chondritic parent bodies produces typical textures, visible under the microscope, which are a consequence of structural deformation of the crystals. Such deformations can be studied with Raman spectroscopy. The vibrational characteristics of olivines and pyroxenes, structurally deformed by weak-to-moderate shock metamorphism, have been determined on four Spanish ordinary chondrites (Cañellas, Olmedilla de Alarcón, Reliegos and Olivenza). Such deformations would affect, in principle, the band positions and widths of the Raman spectra peaks. The measured band positions and relative intensities are consistent with chemical composition for olivines and pyroxenes, but show little influence on the degree of shock. However, the full spectral band width of the silicate internal modes shows some dependence on the impact grade, which could be attributed to inhomogeneous effects produced by the impacts.

  10. Shock-darkening in ordinary chondrites: Determination of the pressure-temperature conditions by shock physics mesoscale modeling

    Czech Academy of Sciences Publication Activity Database

    Moreau, J.; Kohout, Tomáš; Wünnemann, K.

    2017-01-01

    Roč. 52, č. 11 (2017), s. 2375-2390 ISSN 1086-9379 Institutional support: RVO:67985831 Keywords : chondrites * pressure-temperature conditions * astrophysics Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.391, year: 2016

  11. Modification of REE distribution of ordinary chondrites from Atacama (Chile) and Lut (Iran) hot deserts: Insights into the chemical weathering of meteorites

    Science.gov (United States)

    Pourkhorsandi, Hamed; D'Orazio, Massimo; Rochette, Pierre; Valenzuela, Millarca; Gattacceca, Jérôme; Mirnejad, Hassan; Sutter, Brad; Hutzler, Aurore; Aboulahris, Maria

    2017-09-01

    The behavior of rare earth elements (REEs) during hot desert weathering of meteorites is investigated. Ordinary chondrites (OCs) from Atacama (Chile) and Lut (Iran) deserts show different variations in REE composition during this process. Inductively coupled plasma-mass spectrometry (ICP-MS) data reveal that hot desert OCs tend to show elevated light REE concentrations, relative to OC falls. Chondrites from Atacama are by far the most enriched in REEs and this enrichment is not necessarily related to their degree of weathering. Positive Ce anomaly of fresh chondrites from Atacama and the successive formation of a negative Ce anomaly with the addition of trivalent REEs are similar to the process reported from Antarctic eucrites. In addition to REEs, Sr and Ba also show different concentrations when comparing OCs from different hot deserts. The stability of Atacama surfaces and the associated old terrestrial ages of meteorites from this region give the samples the necessary time to interact with the terrestrial environment and to be chemically modified. Higher REE contents and LREE-enriched composition are evidence of contamination by terrestrial soil. Despite their low degrees of weathering, special care must be taken into account while working on the REE composition of Atacama meteorites for cosmochemistry applications. In contrast, chondrites from the Lut desert show lower degrees of REE modification, despite significant weathering signed by Sr content. This is explained by the relatively rapid weathering rate of the meteorites occurring in the Lut desert, which hampers the penetration of terrestrial material by forming voluminous Fe oxide/oxyhydroxides shortly after the meteorite fall.

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

    Science.gov (United States)

    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.

  13. Mössbauer parameters of ordinary chondrites influenced by the fit accuracy of the troilite component: an example of Chelyabinsk LL5 meteorite

    Energy Technology Data Exchange (ETDEWEB)

    Maksimova, A. A. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation); Klencsár, Z. [Hungarian Academy of Sciences, Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences (Hungary); Oshtrakh, M. I., E-mail: oshtrakh@gmail.com; Petrova, E. V.; Grokhovsky, V. I. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation); Kuzmann, E.; Homonnay, Z. [Eötvös Loránd University, Institute of Chemistry (Hungary); Semionkin, V. A. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation)

    2016-12-15

    The influence of the fit accuracy of the troilite component in the Mössbauer spectra of ordinary chondrites on the parameters obtained for other spectral components was evaluated using the Mössbauer spectrum of Chelyabinsk LL5 meteorite fragment with light lithology as a typical example. It was shown that with respect to the application of a usual sextet component where quadrupole interaction is taken into account in the first-order perturbation limit, substantial improvement of the spectrum fit can be achieved either by using the full Hamiltonian description of the troilite component or by its formal approximation with the superposition of three symmetric doublet components. Parameter values obtained for the main spectral components related to olivine and pyroxene were not sensitive to the fit of troilite component while parameters of the minor spectral components depended on the way of troilite component fitting.

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

    Science.gov (United States)

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

    2014-01-01

    Abiotic generation of complex organic compounds, in the early solar nebula that formed our solar system, is hypothesized by some to occur via Fischer-Tropsch (FT) synthesis. In its simplest form, FT synthesis involves the low temperature (300degC) produces FT products that include lesser amounts of n-alkanes and greater alkene, alcohol, and polycyclic aromatic hydrocarbon (PAH) compounds. We have begun to experimentally investigate FT synthesis in the context of abiotic generation of organic compounds in the early solar nebula. It is generally thought that the early solar nebula included abundant hydrogen and carbon monoxide gases and nano-particulate matter such as iron and metal silicates that could have catalyzed the FT reaction. The effect of FT reaction temperature, catalyst type, and experiment duration on the resulting products is being investigated. These solid organic products are analyzed by thermal-stepwise pyrolysis-GCMS and yield the types and distribution of hydrocarbon compounds released as a function of temperature. We show how the FT products vary by reaction temperature, catalyst type, and experimental duration and compare these products to organic compounds found to be indigenous to ordinary chondrite meteorites. We hypothesize that the origin of organics in some chondritic meteorites, that represent an aggregation of materials from the early solar system, may at least in part be from FT synthesis that occurred in the early solar nebula.

  15. The S(IV)-type Asteroids as Ordinary Chondrite Parent Body Candidates: Implications for the Completeness of the Meteorite Sample of Asteroids

    Science.gov (United States)

    Gaffey, M. J.

    1995-09-01

    The discrepancy between the abundance of ordinary chondrites (OCs) among the meteorites and the rarity of unambiguously similar assemblages in the asteroid belt has been a major point of discussion within and between the asteroid and meteorite communities. Various resolutions to this apparent paradox have been proposed [e.g., 1-5], including: 1) interpretations of S-type asteroid spectra are incorrect due to space weathering effects; 2) ordinary chondrites derive from a few rare but favorably situated parent bodies; 3) OCs come from a residual population of small unheated mainbelt asteroids; 4) shock effects darken OC parent body surfaces disguising them as C-type asteroids, and 5) OCs come from inner solar system planetesimals ejected to the Oort cloud which have been recently perturbed into Earth-crossing orbits. Although none of these possibilities has yet been rigorously excluded, recent investigations suggest that the resolution of the apparent paradox lies in some combination of the first three options. For option 3, the discovery of a small mainbelt asteroid with an OC-like spectrum indicates OC-assemblages among the smaller mainbelt asteroids [6], although their abundance is still low in the current sample [7]. For option 2, the mineralogical survey indicated that while most S-asteroids could be rigorously excluded on mineralogical criteria, the S(IV) subtype of this class has silicate compositions within the OC range [8]. The S(IV)-objects are concentrated near the 3:1 secular resonance at 2.5 AU providing an efficient escape into Earth-crossing orbits. Unfortunately for a simple resolution of the OC parent body question, S(IV) spectra still exhibit weaker silicate features and redder spectral slopes than OC assemblages. Although significant uncertainties remain, optical alteration of asteroid surfaces interpreted from the Galileo images of Ida and Gaspra may reconcile the mismatch between OC and S(IV) spectra [option 1]. Although only a subset of the S

  16. Carbon and Oxygen Isotope Measurements of Ordinary Chondrite (OC) Meteorites from Antarctica Indicate Distinct Carbonate Species Using a Stepped Acid Extraction Procedure

    Science.gov (United States)

    Evans, Michael E.

    2015-01-01

    The purpose of this study is to characterize the stable isotope values of terrestrial, secondary carbonate minerals from five Ordinary Chondrite (OC) meteorites collected in Antarctica. These samples were identified and requested from NASA based upon their size, alteration history, and collection proximity to known Martian meteorites. They are also assumed to be carbonate-free before falling to Earth. This research addresses two questions involving Mars carbonates: 1) characterize terrestrial, secondary carbonate isotope values to apply to Martian meteorites for isolating in-situ carbonates, and 2) increase understanding of carbonates formed in cold and arid environments with Antarctica as an analog for Mars. Two samples from each meteorite, each approximately 0.5 grams, were crushed and dissolved in pure phosphoric acid for 3 sequential reactions: a) R times 0 for 1 hour at 30 degrees Centigrade (fine calcite extraction), b) R times 1 for 18 hours at 30 degrees Centigrade (course calcite extraction), and c) R times 2 for 3 hours at 150 degrees Centigrade (siderite and/or magnesite extraction). CO (sub 2) was distilled by freezing with liquid nitrogen from each sample tube, then separated from organics and sulfides with a TRACE GC using a Restek HayeSep Q 80/100 6 foot 2 millimeter stainless column, and then analyzed on a Thermo MAT 253 Isotope Ratio Mass Spectrometer (IRMS) in Dual Inlet mode. This system was built at NASA/JSC over the past 3 years and proof-tested with known carbonate standards to develop procedures, assess yield, and quantify expected error bands. Two distinct species of carbonates are found: 1) calcite, and 2) non-calcite carbonate (future testing will attempt to differentiate siderite from magnesite). Preliminary results indicate the terrestrial carbonates are formed at approximately sigma (sup 13) C equal to plus 5 per mille, which is consistent with atmospheric CO (sub 2) sigma (sup 13) C equal to minus 7 per mille and fractionation of plus

  17. Carbon and Oxygen Isotope Measurements of Ordinary Chondrite (OC) Meteorites from Antarctica Indicate Distinct Terrestrial Carbonate Species using a Stepped Acid Extraction Procedure Impacting Mars Carbonate Research

    Science.gov (United States)

    Evans, M. E.; Niles, P. B.; Locke, D.

    2015-12-01

    The purpose of this study is to characterize the stable isotope values of terrestrial, secondary carbonate minerals from five OC meteorites collected in Antarctica. These samples were selected for analysis based upon their size and collection proximity to known Martian meteorites. They were also selected based on petrologic type (3+) such that they were likely to be carbonate-free before falling to Earth. This study has two main tasks: 1) characterize the isotopic composition of terrestrial, secondary carbonate minerals formed on meteorites in Antarctica, and 2) study the mechanisms of carbonate formation in cold and arid environments with Antarctica as an analog for Mars. Two samples from each meteorite, each ~0.5g, was crushed and dissolved in pure phosphoric acid for 3 sequential reactions: a) Rx0 for 1 hour at 30°C, b) Rx1 for 18 hours at 30°C, and c) Rx2 for 3 hours at 150°C. CO2 was distilled by freezing with liquid nitrogen from each sample tube, then separated from organics and sulfides with a TRACE GC using a Restek HayeSep Q 80/100 6' 2mm stainless column, and then analyzed on a Thermo MAT 253 IRMS in Dual Inlet mode. This system was built at NASA/JSC over the past 3 years and proof tested with known carbonate standards to develop procedures, assess yield, and quantify expected uncertainties. Two distinct species of carbonates are found based on the stepped extraction technique: 1) Ca-rich carbonate released at low temperatures, and 2) Mg, or Fe-rich carbonate released at high temperatures. Preliminary results indicate that most of the carbonates present in the ordinary chondrites analyzed have δ13C=+5‰, which is consistent with formation from atmospheric CO2 δ13C=-7‰ at -20°C. The oxygen isotopic compositions of the carbonates vary between +4‰ and +34‰ with the Mg-rich and/or Fe-rich carbonates possessing the lowest δ18O values. This suggests that the carbonates formed under a wide range of temperatures. However, the carbonate oxygen

  18. A partial melting study of an ordinary (H) chondrite composition with application to the unique achondrite Graves Nunataks 06128 and 06129

    Science.gov (United States)

    Usui, Tomohiro; Jones, John H.; Mittlefehldt, David W.

    2015-04-01

    Melting experiments of a synthesized, alkali-bearing, H-chondrite composition were conducted at ambient pressure with three distinct oxygen fugacity conditions (IW-1, IW, and IW+2). Oxygen fugacity conditions significantly influence the compositions of partial melts. Partial melts at IW-1 are distinctly enriched in SiO2 relative to those of IW and IW+2 melts. The silica-enriched, reduced (IW-1) melts are characterized by high alkali contents and have silica-oversaturated compositions. In contrast, the silica-depleted, oxidized (≥IW) melts, which are also enriched in alkali contents, have distinctly silica-undersaturated compositions. These experimental results suggest that alkali-rich, felsic, asteroidal crusts as represented by paired achondrites Graves Nunataks 06128 and 06129 should originate from a low-degree, relatively reduced partial melt from a parent body having near-chondritic compositions. Based on recent chronological constraints and numerical considerations as well as our experimental results, we propose that such felsic magmatism should have occurred in a parent body that is smaller in size and commenced accreting later than those highly differentiated asteroids having basaltic crusts and metallic cores.

  19. Shock metamorphism of carbonaceous chondrites

    Science.gov (United States)

    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.

  20. Lunar and Planetary Science XXXV: Concerning Chondrites

    Science.gov (United States)

    2004-01-01

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

  1. Solar nebula magnetic fields recorded in the Semarkona meteorite

    DEFF Research Database (Denmark)

    Fu, Roger R.; Weiss, Benjamin P.; Lima, Eduardo A.

    2014-01-01

    on the intensity of these fields. Here we show that dusty olivine-bearing chondrules from the Semarkona meteorite were magnetized in a nebular field of 54 ± 21 microteslas. This intensity supports chondrule formation by nebular shocks or planetesimal collisions rather than by electric currents, the x......Magnetic fields are proposed to have played a critical role in some of the most enigmatic processes of planetary formation by mediating the rapid accretion of disk material onto the central star and the formation of the first solids. However, there have been no experimental constraints......-wind, or other mechanisms near the Sun. This implies that background magnetic fields in the terrestrial planet-forming region were likely 5 to 54 microteslas, which is sufficient to account for measured rates of mass and angular momentum transport in protoplanetary disks....

  2. Paleomagnetism. Solar nebula magnetic fields recorded in the Semarkona meteorite.

    Science.gov (United States)

    Fu, Roger R; Weiss, Benjamin P; Lima, Eduardo A; Harrison, Richard J; Bai, Xue-Ning; Desch, Steven J; Ebel, Denton S; Suavet, Clément; Wang, Huapei; Glenn, David; Le Sage, David; Kasama, Takeshi; Walsworth, Ronald L; Kuan, Aaron T

    2014-11-28

    Magnetic fields are proposed to have played a critical role in some of the most enigmatic processes of planetary formation by mediating the rapid accretion of disk material onto the central star and the formation of the first solids. However, there have been no experimental constraints on the intensity of these fields. Here we show that dusty olivine-bearing chondrules from the Semarkona meteorite were magnetized in a nebular field of 54 ± 21 microteslas. This intensity supports chondrule formation by nebular shocks or planetesimal collisions rather than by electric currents, the x-wind, or other mechanisms near the Sun. This implies that background magnetic fields in the terrestrial planet-forming region were likely 5 to 54 microteslas, which is sufficient to account for measured rates of mass and angular momentum transport in protoplanetary disks. Copyright © 2014, American Association for the Advancement of Science.

  3. Netschaevo: a new class of chondritic meteorite.

    Science.gov (United States)

    Bild, R W; Wasson, J T

    1977-07-01

    The ratios of refractory elements to silicon and of zinc to silicon indicate that the silicate portion of the Netschaëvo meteorite is an ordinary chondrite. The scarcity of chondrules, the large dimensions (about 100 micrometers) of plagioclase grains, and the low indium content (0.09 nanogram per gram) indicate that Netschaëvo belongs to petrologic type 6. On a diagram of reduced iron versus oxidized iron, Netschaëvo lies along an extrapolation of the LL-L-H ordinary chondrite fractionation trend. The abundances of siderophile elements (nickel, germanium, iridium, and gold) are about 1.6 to 2.0 times greater than in H-group chondrites, and siderophile/nickel ratios are, with one exception, those expected from LL-L-H trends. This evidence indicates that Netschaëvo is an extremely iron-rich member of the ordinary chondrite sequence, and that plausible models to account for the ordinary chondrite sequence must produce materials having iron/silicon ratios 25 percent greater than those in CI carbonaceous chondrites. The existence of Netschaëvo emphasizes that the chondritic meteorites in terrestrial collections are a biased and incomplete selection of primitive solar system materials.

  4. Ordinary chondritic micrometeorites from the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    ShyamPrasad, M.; Rudraswami, N.G.; Babu, E.V.S.S.K.; VijayaKumar, T.

    are found to enclose chromite grains (Table 1). Five of them have one chromite grain in the cross section observed, however, two spherules have more than one : AAS38-155#1-P6 contains 10 chromite grains, the largest of which is ~80 µm (Fig. 1 A...,B), and AAS38-178#1-P3 has two chromite grains, respectively (Fig. 1E,F). The spherules that contain chromites have a diameter range of 230-443 µm (majority of them between 230 – 300 µm). Out of the seven spherules that enclose chromites five have a...

  5. Diffusion Modeling of Cooling Rates of Relict Olivine in Semarkona Chondrules

    Science.gov (United States)

    Hewins, R. H.; Ganguly, J.; Mariani, E.

    2009-03-01

    Diffusive exchange profiles between relict olivine and melt-grown olivine in Semarkona Type IIA chondrules were oriented by EBSD to correct D. Results for Fe-Mg (D from Dohmen) and Cr (Ito and Ganguly) are concordant at 300°-400°C/hr.

  6. Mineralogy and chemistry of Rumuruti: The first meteorite fall of the new R chondrite group

    Science.gov (United States)

    Schulze, H.; Bischoff, A.; Palme, H.; Spettel, B.; Dreibus, G.; Otto, J.

    1994-03-01

    The Rumuruti meteorite shower fell in Rumuruti, Kenya, on 1934 January 28 at 10:45 p.m. Rumuruti is an olivine-rich chondritic breccia with light-dark structure. Based on the coexistence of highly recrystallized fragments and unequilibrated components, Rumuruti is classified as a type 3-6 chondrite breccia. The most abundant phase of Rumuruti is olivine (mostly Fa(approximately 39) with about 70 vol%. Feldspar (approximately 14 vol%; mainly plagioclase), Ca-pyroxene (5 vol%), pyrrhotite (4.4 vol%), and pentlandite (3.6 vol%) are major constituents. All other phases have abundances below 1 vol%, including low-Ca pyroxene, chrome spinels, phosphates (chlorapatite and whitlockite), chalcopyrite, ilemenite, tridymite, Ni-rich and Ge-containing metals, kamacite, and various particles enriched in noble metals like Pt, Ir, and Au. The chemical composition of Rumuruti is chondritic. The depletion in refractory elements (Sc, REE, etc.) and the comparatively high Mn, Na, and K contents are characteristic of ordinary chondrites and distinguish Rumuruti from carbonaceous chondrites. However, S, Se, and Zn contents in Rumuruti are significantly above the level expected for ordinary chondrites. The oxygen isotope composition of Rumuruti is high in delta O-17 (5.52%) and delta O-18 (5.07%). With Rumuruti, nine meteorites samples exist that are chemically and mineralogically very similar. These meteorites are attributed to at least eight different fall events. It is proposed in this paper to call this group R chondrites (rumurutites) after the first and only fall among these meteorites. The meteorites have a close relationship to ordinary chondrites. However, they are more oxidized than any of the existing groups of ordinary chondrites. Small, but significant differences in chemical composition and in oxygen isotopes between R chondrites and ordinary chondrites exclude formation of R chondrites from ordinary chondrites by oxidation. This implies a separate, independent R chondrite

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

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, Yasuhiro; Turner, Neal J.; Masiero, Joseph [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Wakita, Shigeru; Matsumoto, Yuji; Oshino, Shoichi, E-mail: yasuhiro@caltech.edu [Center for Computational Astrophysics, National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588 (Japan)

    2016-03-20

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

  8. New kind of type 3 chondrite with a graphite-magnetite matrix

    Science.gov (United States)

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

    1981-01-01

    Four clasts in three ordinary-chondrite regolith breccias are discovered which are a new kind of type 3 chondrite. As with ordinary and carbonaceous type 3 chondrites, they have distinct chondrules, some of which contain glass, highly heterogeneous olivines and pyroxenes, and predominantly monoclinic low-Ca pyroxenes. Instead of the usual, fine-grained, Fe-rich silicate matrix, however, the clasts have a matrix composed largely of aggregates of micron- and submicron-sized graphite and magnetite. The bulk compositions of the clasts, as well as the types of chondrules (largely porphyritic), are characteristic of type 3 ordinary chondrites, although chondrules in the clasts are somewhat smaller (0.1-0.5 mm). A close relationship with ordinary chondrites is also suggested by the presence of similar graphite-magnetite aggregates in seven type 3 ordinary chondrites. It is thought that this new kind of chondrite is probably the source of the abundant graphite-magnetite inclusions in ordinary-chondrite regolith breccias and that it may be more common than indicated by the absence of whole meteorites made of chondrules and graphite-magnetite.

  9. Do L chondrites Come From the Gefion Family?

    Science.gov (United States)

    McGraw, Allison M.; Reddy, Vishnu; Sanchez, Juan A.

    2018-01-01

    Ordinary chondrites (H, L and LL chondrites) are the most common type of meteorites comprising 80% of the meteorites that fall on Earth. The source region of these meteorites in the main asteroid belt has been a basis of considerable debate in the small bodies community. L chondrites have been proposed to come from the Gefion asteroid family, based on dynamical models. We present results from our observational campaign to verify a link between the Gefion asteroid family and L chondrite meteorites. Near-infrared spectra of Gefion family asteroids (1839) Ragazza, (2373) Immo, (2386) Nikonov, (2521) Heidi and (3860) Plovdiv were obtained at the NASA Infrared Telescope Facility (IRTF). Spectral band parameters including Band centers and the Band Area Ratio were measured from each spectrum and used to constrain the composition of these asteroids. Based on our results, we found that some members of the Gefion family have surface composition similar to that of H chondrites, primitive achondrites and basaltic achondrites. No evidence was found for L chondrites among the Gefion family members in our small sample study. The diversity of compositional types observed in the Gefion asteroid family suggests that the original parent body might be partially differentiated or that the three asteroids with non-ordinary chondrite compositions might be interlopers.

  10. Secondary melting events in Semarkona chondrules revealed by compositional zoning in low-Ca pyroxene

    Science.gov (United States)

    Baecker, Bastian; Rubin, Alan E.; Wasson, John T.

    2017-08-01

    It is well established that many chondrules contain relict grains formed in previous generations of chondrules. We here describe evidence that chondrules experienced multiple mesostasis melting events while remaining closed systems. Spheroidal chondrule shapes resulted from surface-tension effects following a primary heating event that caused substantial melting (≳40%) of the precursor assemblages. In some high-FeO chondrules in LL3.00 Semarkona, low-Ca pyroxene phenocrysts show multiple overgrowth layers produced by secondary melting events. We characterized these layers with the electron microprobe in terms of Fe, Ca and Cr in two Semarkona chondrules. The first low-Ca pyroxene overgrowth that forms after a minor heating/melting event has low Ca and Fe; concentrations of these incompatibles gradually increase over the next 8 ± 4 μm until falling temperatures and slowing diffusion caused growth to stop. The next melting event remelts and mixes the local mesostasis; cooling causes growth of a normal igneously zoned layer. In the simplest cases, the Ca concentrations at the minima gradually increase towards the edge of the phenocryst. Heat deposition during heating events varied over a wide range; the weakest events produced recognizable changes in slopes (that we call "inflections" rather than minima). Large fractions of the individual phenocrysts were formed by the process that produced the overgrowth layers. It appears that overgrowth formation stopped when the Ca content of the mesostasis became high enough to make high-Ca pyroxene a liquidus phase. Both Semarkona chondrules include olivine phenocrysts similar in size and modal abundance to the low-Ca pyroxene phenocrysts. Olivine compositional profiles show symmetrical, apparently normal zoning except for asymmetries attributable to the presence of relict grains. Surface compositions of different olivine phenocrysts in the same chondrule are very similar to one another, consistent with growth from

  11. Application of Image Analysis in Optical Microscopy of Ordinary Chondrites

    Science.gov (United States)

    Petrova, E. V.; Petrov, M. S.; Grokhovsky, V. I.

    2017-11-01

    Application of image analysis systems give additional possibilities for estimation, calculation and comparison of optical microscopic images. Different parameters of the texture (phase distribution, porosity, grains shape parameters) can be obtained.

  12. The Behavior of Halogens Elements in the Early Solar System: Constraints from the Complex Record in Chondritic Meteorites

    Science.gov (United States)

    Brearley, A. J.; Jones, R. H.

    2016-12-01

    The volatile inventory of chondritic meteorites was established by a range of processes that occurred in circumstellar and interstellar environments, within the solar nebula, and after accretion within meteorite parent bodies. Among volatile elements, the halogens are of particular interest because, although they exhibit similar geochemical characteristics, they have a range of volatilities that control their cosmochemical behavior. Chondritic meteorites provide the opportunity to understand how halogens behaved during the earliest history of our solar system, including during condensation, CAI and chondrule formation in the protoplanetary disk, and during subsequent processing after accretion into asteroidal parent bodies by aqueous alteration, metamorphism and shock. Constraints on the halogen inventory of the terrestrial planets also requires a detailed knowledge of halogen abundances in chondritic meteorites. However, the full potential of halogens to constrain processes in the solar nebula and chondrite parent bodies has not yet been realized because of significant analytical challenges and uncertainties in halogen condensation temperatures. Nevertheless, although there are significant variations in the analytical data, it is clear that there are distinct differences between the three main classes of chondrites, carbonaceous, ordinary, and enstatite. In most chondrites, the abundances of the halogens are controlled by their cosmochemical volatility, and the halogens are depleted in most of the chondrite groups relative to CI chondrites. With the exception of the enstatite chondrites, the primary (nebular) mineralogical carriers of the halogens in the most pristine (type 3) carbonaceous and ordinary chondrites are poorly constrained, suggesting that they are incorporated at low concentrations into nebular phases. In aqueously-altered, petrologic type 1 and 2 meteorites, no distinct halogen-bearing phases have been identified. However, metamorphic processes

  13. Transcendentalism and the Ordinary

    OpenAIRE

    Laugier, Sandra

    2017-01-01

    For Stanley Cavell, the specific and contemporary theme of the ordinary sets off from America and the transcendentalism of Emerson and Thoreau, in order to reinvent itself in Europe with ordinary language philosophy – Wittgenstein and Austin. But in order to understand this, it is necessary to perceive what Cavell calls, inspired by Wittgenstein and Thoreau, “the uncanniness of the ordinary,” inherent to its anthropological thematization. In his preface to the recent work of Veena Das, Life a...

  14. Osmium isotopic homogeneity in the CK carbonaceous chondrites

    Science.gov (United States)

    Goderis, Steven; Brandon, Alan D.; Mayer, Bernhard; Humayun, Munir

    2017-11-01

    Variable proportions of isotopically diverse presolar components are known to account for nucleosynthetic isotopic anomalies for a variety of elements (e.g., Ca, Ti, Cr, Ni, Sr, Zr, Mo, Ru, Pd, Ba, Nd, and Sm) in both bulk chondrites and achondrites. However, although large Os isotopic anomalies have been measured in acid leachates and residues of unequilibrated chondrites, bulk chondrites of various groups, iron meteorites, and pallasites exhibit Os isotopic compositions that are indistinguishable from terrestrial or bulk solar isotopic abundances. Since the magnitude of nucleosynthetic anomalies is typically largest in the carbonaceous chondrites, this study reports high-precision Os isotopic compositions and highly siderophile element (HSE) concentrations for ten CK chondrites. The isotope dilution concentration data for HSE and high-precision Os isotope ratios were determined on the same digestion aliquots, to precisely correct for radiogenic contributions to 186Os and 187Os. While acid leached bulk unequilibrated carbonaceous chondrites show deficits of s-process Os components to the same extent as revealed by unequilibrated enstatite, ordinary, and Rumuruti chondrites, equilibrated bulk CK chondrites exhibit no resolvable Os isotopic anomalies. These observations support the idea that acid-resistant, carbon-rich presolar grains, such as silicon carbide (SiC) or graphite, are major carriers for nucleosynthetic isotopic anomalies of Os. The destruction of these presolar grains, which are omnipresent in unequilibrated meteorites, must have occurred during aqueous alteration and thermal metamorphism, early in the CK chondrite parent body history. The dispersal of CK chondrites along the IIIAB iron meteorite isochron on a 187Os/188Os versus 187Re/188Os diagram, with Re/Os ratios from 0.032 to 0.083, in combination with the observed redistribution of other HSE (e.g., Pt, Pd), highlights the influence of parent body processes, overprinted by effects of recent

  15. Ringwoodite in shocked chondrites

    Science.gov (United States)

    Lingemann, C. M.; Stoffler, D.

    1994-07-01

    Since the discovery of ringwoodite in the meteorite Tenham, further studies confirmed that this mineral occurs preferentially in melt veins and melt pockets of highly shocked L chondrules. Except for some special Transmission Electron Microscopy (TEM) studies a comprehensive study of this high-pressure phase of olivine in the general scope of shock metamorphism of chondrites is missing. Eighteen ringwoodite-bearing L6(S6) chondrites were studied, some of them in more detail: L6(S6)-Catherwood, L6(S6)-Coorara, L6(S6)-Johnson City, L6(S6)-Pampa del Infierno, L6(S6)-Tenham, and L5-6(S6)-Acfer 040. They were analyzed by the optical microscope, Scanning Electron Microscopy (SEM), microprobe, and TEM. Ringwoodite is formed in chondrites at locations where localized melting occurs by shock waves exceeding 50 GPa. The localized shock-pressure and temperature concentrations are obviously favorable for the kinetics of the olivine-spinel transition. Ringwoodite crystallizes most probably not during the short peak pressure pulse but rather during the more extended phase of pressure release, where the temperature is still extremely high, presumably near the solidus of chondrites. The observed chemical variation of individual ringwoodite grains and the indication that wadsleyite coexists with ringwoodite, could be explained as follows. On release from a high-pressure-shock state, olivine transforms to an assemblage of the Beta phase (wadsleyite) and the gamma phase (ringwoodite) in the pressure range between about 20 and 13 GPa. In the two-phase region, where the Beta and gamma phases coexist under equilibrium conditions, the two phases would have compositions in the range Fa(13-25) and Fa(25-31) respectively if the primary olivine composition is 24-25 mol% Fa. This range is very near to the observed chemical variation within polycrystalline ringwoodite grains Fa(19-31).

  16. Long-lived magnetism on chondrite parent bodies

    Science.gov (United States)

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

    2017-10-01

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

  17. Ordinary differential equations

    CERN Document Server

    Pontryagin, Lev Semenovich

    1962-01-01

    Ordinary Differential Equations presents the study of the system of ordinary differential equations and its applications to engineering. The book is designed to serve as a first course in differential equations. Importance is given to the linear equation with constant coefficients; stability theory; use of matrices and linear algebra; and the introduction to the Lyapunov theory. Engineering problems such as the Watt regulator for a steam engine and the vacuum-tube circuit are also presented. Engineers, mathematicians, and engineering students will find the book invaluable.

  18. Fluid Inclusions in Carbonaceous Chondrites

    Science.gov (United States)

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

    2001-01-01

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

  19. Cat Mountain: A meteoritic sample of an impact-melted chondritic asteroid

    Science.gov (United States)

    Kring, David A.

    1993-01-01

    Although impact cratering and collisional disruption are the dominant geologic processes affecting asteroids, samples of impact melt breccias comprise less than 1 percent of ordinary chondritic material and none exist among enstatite and carbonaceous chondrite groups. Because the average collisional velocity among asteroids is sufficiently large to produce impact melts, this paucity of impact-melted material is generally believed to be a sampling bias, making it difficult to determine the evolutionary history of chondritic bodies and how impact processes may have affected the physical properties of asteroids (e.g., their structural integrity and reflectance spectra). To help address these and related issues, the first petrographic description of a new chondritic impact melt breccia sample, tentatively named Cat Mountain, is presented.

  20. Temperature and Oxygen Fugacity Constraints on CK and R Chondrites and Implications for Water and Oxidation in the Early Solar System

    Science.gov (United States)

    Righter, K.; Neff, K. E.

    2007-01-01

    Recent chondritic meteorite finds in Antarctica have included CB, CH, CK and R chondrites, the latter two of which are among the most oxidized materials found in meteorite collections. In this study we present petrographic and mineralogic data for a suite of CK and R chondrites, and compare to previous studies of CK and R, as well as some CV chondrites. In particular we focus on the opaque minerals magnetite, chromite, sulfides, and metal as well as unusual silicates hornblende, biotite, and plagioclase. Several mineral thermometers and oxy-barometers are utilized to calculate temperatures and oxygen fugacities for these unusual meteorites compared to other more common chondrite groups. R and CK chondrites show lower equilibrium temperatures than ordinary chondrites, even though they are at similar petrologic grades (e.g., thermal type 6). Oxygen fugacity calculated for CV and R chondrites ranges from values near the iron-wustite (IW) oxygen buffer to near the fayalite-magnetite-quartz (FMQ) buffer. In comparison, the fO2 recorded by ilmenite-magnetite pairs from CK chondrites are much higher, from FMQ+3.1 to FMQ+5.2. The latter values are the highest recorded for materials in meteorites, and place some constraints on the formation conditions of these magnetite-bearing chondrites. Differences between mineralogic and O isotopic compositions of CK and R chondrites suggest two different oxidation mechanisms, which may be due to high and low water: rock ratios during metamorphism, or to different fluid compositions, or both.

  1. Celebrating the Ordinary

    Science.gov (United States)

    Horst, Carol

    2010-01-01

    Memento. Memoir. Memorable. Memory. Memorial. Commemorate. In Memoriam. These words may remind a person of stone monuments, or larger-than-life heroes and loved ones far distanced by space and time. The act of remembering, though, also belongs in the world of the everyday and the ordinary, and has a valuable place in an art classroom. In this…

  2. Thermal evolution model for the H chondrite asteroid-instantaneous formation versus protracted accretion

    Science.gov (United States)

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

    2013-09-01

    We present a model of the thermal evolution of asteroids. Assuming an onion shell model for the H chondrite parent body we obtain constraints for the H chondrite asteroid parameters by fitting empirical H chondrite cooling ages of Estacado, Guareña, Kernouvé, Mt. Browne, Richardton, Allegan, Nadiabondi, Ste. Marguerite, and Forest Vale by using a genetic algorithm for parameter optimisation. The model improves previous calculations on the thermal history calculated in the instantaneous accretion approximation considering sintering and porosity dependent heat conduction. The model is extended to include a finite growth time of the parent body to study whether the meteoritic record constrains the duration of the growth phase of the parent body where it assembles most of its mass. It is found that only short accretion times of up to 0.1 Ma are compatible with the empirical data on H chondrite cooling histories. Best fit models yield excellent agreement with the cooling age data. Particularly, they indicate that (i) 26Al was the major heat source driving metamorphism, while 60Fe contributed rather marginally, (ii) maximum temperatures remained below partial melting temperatures throughout the body, indicating that no partial differentiation occurred on the H chondrite parent asteroid, (iii) the H chondrite asteroid formed 2 Ma after CAIs, briefly after most ordinary chondrite chondrules formed (if 26Al abundance defines a chronological sequence).

  3. Fe-Ni metal and sulfide minerals in CM chondrites: An indicator for thermal history

    Science.gov (United States)

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

    2011-01-01

    CM chondrites were subjected to aqueous alteration and, in some cases, to secondary metamorphic heating. The effects of these processes vary widely, and have mainly been documented in silicate phases. Herein, we report the characteristic features of Fe-Ni metal and sulfide phases in 13 CM and 2 CM-related chondrites to explore the thermal history of these chondrites. The texture and compositional distribution of the metal in CM are different from those in unequilibrated ordinary and CO chondrites, but most have similarities to those in highly primitive chondrites, such as CH, CR, and Acfer 094. We classified the CM samples into three categories based on metal composition and sulfide texture. Fe-Ni metal in category A is kamacite to martensite. Category B is characterized by pyrrhotite grains always containing blebs or lamellae of pentlandite. Opaque mineral assemblages of category C are typically kamacite, Ni-Co-rich metal, and pyrrhotite. These categories are closely related to the degree of secondary heating and are not related to degree of the aqueous alteration. The characteristic features of the opaque minerals can be explained by secondary heating processes after aqueous alteration. Category A CM chondrites are unheated, whereas those in category B experienced small degrees of secondary heating. CMs in category C were subjected to the most severe secondary heating process. Thus, opaque minerals can provide constraints on the thermal history for CM chondrites. ?? The Meteoritical Society, 2011.

  4. Halogens in chondritic meteorites and terrestrial accretion

    Science.gov (United States)

    Clay, Patricia L.; Burgess, Ray; Busemann, Henner; Ruzié-Hamilton, Lorraine; Joachim, Bastian; Day, James M. D.; Ballentine, Christopher J.

    2017-11-01

    Volatile element delivery and retention played a fundamental part in Earth’s formation and subsequent chemical differentiation. The heavy halogens—chlorine (Cl), bromine (Br) and iodine (I)—are key tracers of accretionary processes owing to their high volatility and incompatibility, but have low abundances in most geological and planetary materials. However, noble gas proxy isotopes produced during neutron irradiation provide a high-sensitivity tool for the determination of heavy halogen abundances. Using such isotopes, here we show that Cl, Br and I abundances in carbonaceous, enstatite, Rumuruti and primitive ordinary chondrites are about 6 times, 9 times and 15-37 times lower, respectively, than previously reported and usually accepted estimates. This is independent of the oxidation state or petrological type of the chondrites. The ratios Br/Cl and I/Cl in all studied chondrites show a limited range, indistinguishable from bulk silicate Earth estimates. Our results demonstrate that the halogen depletion of bulk silicate Earth relative to primitive meteorites is consistent with the depletion of lithophile elements of similar volatility. These results for carbonaceous chondrites reveal that late accretion, constrained to a maximum of 0.5 ± 0.2 per cent of Earth’s silicate mass, cannot solely account for present-day terrestrial halogen inventories. It is estimated that 80-90 per cent of heavy halogens are concentrated in Earth’s surface reservoirs and have not undergone the extreme early loss observed in atmosphere-forming elements. Therefore, in addition to late-stage terrestrial accretion of halogens and mantle degassing, which has removed less than half of Earth’s dissolved mantle gases, the efficient extraction of halogen-rich fluids from the solid Earth during the earliest stages of terrestrial differentiation is also required to explain the presence of these heavy halogens at the surface. The hydropilic nature of halogens, whereby they track

  5. Laser Ablation Experiments on the Tamdakht H5 Chondrite

    Science.gov (United States)

    White, Susan M.; Stern, Eric

    2017-01-01

    High-powered lasers were used to induce ablation and to form fusion crusts in the lab on Tamdakht H5 chondrites and basalt. These ground tests were undertaken to improve our understanding, and ultimately improve our abilty to model and predict, meteoroid ablation during atmospheric entry. The infrared fiber laser at the LHMEL facilty, operated in the continuous wave (i.e. non-pulsed) mode, provided radiation surface heat flux at levels similar to meteor entry for these tests. Results are presented from the first round of testing on samples of Tamdakht H5 ordinary chondrite which were ex-posed to entry-relevant heating rates between 2 and 10 kWcm2.

  6. Aiming for the ordinary

    DEFF Research Database (Denmark)

    Offersen, Sara Marie Hebsgaard

    as the ‘patient interval’, cancer disease control has firmly entered the domains of everyday life, continuously expanding its presence and likely affects what counts as ordinary and extraordinary bodily experience. However, most studies of symptom experience and healthcare seeking in this field have been...... conducted retrospectively among already diagnosed patients. Hence, we do not know much about neither how these processes and changing approaches play out in everyday life among non-cancer-afflicted people, nor about how symptoms in the first place arise out of culturally contingent experience, organization...... on a continuum between what is locally considered ordinary and extraordinary. Overall, the dissertation argues that inquiries into morality and potentiality provide valuable insights into healthcare seeking practices and the making and management of symptoms in everyday life. The dissertation is based on 18...

  7. Ordinary differential equations

    CERN Document Server

    Greenberg, Michael D

    2014-01-01

    Features a balance between theory, proofs, and examples and provides applications across diverse fields of study Ordinary Differential Equations presents a thorough discussion of first-order differential equations and progresses to equations of higher order. The book transitions smoothly from first-order to higher-order equations, allowing readers to develop a complete understanding of the related theory. Featuring diverse and interesting applications from engineering, bioengineering, ecology, and biology, the book anticipates potential difficulties in understanding the various solution steps

  8. Ordinary differential equations.

    Science.gov (United States)

    Lebl, Jiří

    2013-01-01

    In this chapter we provide an overview of the basic theory of ordinary differential equations (ODE). We give the basics of analytical methods for their solutions and also review numerical methods. The chapter should serve as a primer for the basic application of ODEs and systems of ODEs in practice. As an example, we work out the equations arising in Michaelis-Menten kinetics and give a short introduction to using Matlab for their numerical solution.

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

    Science.gov (United States)

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

    2016-09-01

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

  10. Ordinary differential equations

    CERN Document Server

    Cox, William

    1995-01-01

    Building on introductory calculus courses, this text provides a sound foundation in the underlying principles of ordinary differential equations. Important concepts, including uniqueness and existence theorems, are worked through in detail and the student is encouraged to develop much of the routine material themselves, thus helping to ensure a solid understanding of the fundamentals required.The wide use of exercises, problems and self-assessment questions helps to promote a deeper understanding of the material and it is developed in such a way that it lays the groundwork for further

  11. Ordinary differential equations

    CERN Document Server

    Miller, Richard K

    1982-01-01

    Ordinary Differential Equations is an outgrowth of courses taught for a number of years at Iowa State University in the mathematics and the electrical engineering departments. It is intended as a text for a first graduate course in differential equations for students in mathematics, engineering, and the sciences. Although differential equations is an old, traditional, and well-established subject, the diverse backgrounds and interests of the students in a typical modern-day course cause problems in the selection and method of presentation of material. In order to compensate for this diversity,

  12. Ordinary General Assembly

    CERN Multimedia

    Staff Association

    2011-01-01

    Tuesday 12 April at 14.00 Council Chamber, Bldg 503 In conformity with the Statutes of the Staff Association, an ordinary General Assembly is organized once a year (article IV.2.1). Agenda   Adoption of the Agenda Approval of the Draft Minutes of the Ordinary General Assembly of 20 April 2010 Presentation and approval of the Activity Report 2010 Presentation and approval of the Financial Report 2010 Presentation and approval of the Auditors Report 2010 Programme for 2011 Presentation et and approval of the draft budget and subscription rate 2012 Election of the Election Committee Election of the Board of Auditors Miscellaneous We remind members of article IV.3.4 in the Statutes of the Association which reads: “After having dealt with all the items on the agenda, the members may, with the consent of the Assembly, have other matters discussed, but decisions may be taken only on the items listed on the agenda. Nevertheless, the Assembly ma...

  13. Ordinary General Assembly

    CERN Multimedia

    Staff Association

    2010-01-01

    Tuesday 20 April at 10.00 Council Chamber, Bldg 503 In conformity with the Statutes of the Staff Association, an ordinary General Assembly is organized once a year (article IV.2.1). Agenda   Adoption of the Agenda Approval of the Draft Minutes of the Ordinary General Assembly of 12 May 2009 Presentation and approval of the Activity Report 2009 Presentation and approval of the Financial Report 2009 Presentation and approval of the Auditors Report 2009 Programme for 2010 Presentation et and approval of the draft budget and subscription rate 2010 Election of the Election Committee Election of the Board of Auditors Miscellaneous We remind members of article IV.3.4 in the Statutes of the Association which reads: “After having dealt with all the items on the agenda, the members may, with the consent of the Assembly, have other matters discussed, but decisions may be taken only on the items listed on the agenda. Nevertheless, the Assembly may require t...

  14. Ordinary General Assembly

    CERN Multimedia

    Association du personnel

    2010-01-01

    Tuesday 20 April at 10.00 Council Chamber, Bldg 503 In conformity with the Statutes of the Staff Association, an ordinary General Assembly is organized once a year (article IV.2.1). Agenda Adoption of the Agenda Approval of the Draft Minutes of the Ordinary General Assembly of 12 May 2009 Presentation and approval of the Activity Report 2009 Presentation and approval of the Financial Report 2009 Presentation and approval of the Auditors Report 2009 Programme for 2010 Presentation et and approval of the draft budget and subscription rate 2010 Modifications to the statutes of the association Election of the Election Committee Election of the Board of Auditors Miscellaneous We remind members of article IV.3.4 in the Statutes of the Association which reads: “After having dealt with all the items on the agenda, the members may, with the consent of the Assembly, have other matters discussed, but decisions may be taken only on the items listed on the agenda...

  15. Ordinary General Assembly

    CERN Multimedia

    Staff Association

    2011-01-01

    Tuesday 12 April at 14.00 Council Chamber, Bldg 503 In conformity with the Statutes of the Staff Association, an ordinary General Assembly is organized once a year (article IV.2.1). Agenda   Adoption of the Agenda Approval of the Draft Minutes of the Ordinary General Assembly of 20 April 2010 Presentation and approval of the Activity Report 2010 Presentation and approval of the Financial Report 2010 Presentation and approval of the Auditors Report 2010 Programme for 2011 Presentation and approval of the draft budget and subscription rate 2012 Election of the Election Committee Election of the Board of Auditors Miscellaneous We remind members of article IV.3.4 in the Statutes of the Association which reads: “After having dealt with all the items on the agenda, the members may, with the consent of the Assembly, have other matters discussed, but decisions may be taken only on the items listed on the agenda. Nevertheless, the Assembly may r...

  16. Reflectance spectra of primitive chondrites

    Science.gov (United States)

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

    2013-05-01

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

  17. Titanium stable isotopic variations in chondrites, achondrites and lunar rocks

    Science.gov (United States)

    Greber, Nicolas D.; Dauphas, Nicolas; Puchtel, Igor S.; Hofmann, Beda A.; Arndt, Nicholas T.

    2017-09-01

    Titanium isotopes are potential tracers of processes of evaporation/condensation in the solar nebula and magmatic differentiation in planetary bodies. To gain new insights into the processes that control Ti isotopic variations in planetary materials, 25 komatiites, 15 chondrites, 11 HED-clan meteorites, 5 angrites, 6 aubrites, a martian shergottite, and a KREEP-rich impact melt breccia have been analyzed for their mass-dependent Ti isotopic compositions, presented using the δ49Ti notation (deviation in permil of the 49Ti/47Ti ratio relative to the OL-Ti standard). No significant variation in δ49Ti is found among ordinary, enstatite, and carbonaceous chondrites, and the average chondritic δ49Ti value of +0.004 ± 0.010‰ is in excellent agreement with the published estimate for the bulk silicate Earth, the Moon, Mars, and the HED and angrite parent-bodies. The average δ49Ti value of komatiites of -0.001 ± 0.019‰ is also identical to that of the bulk silicate Earth and chondrites. OL-Ti has a Ti isotopic composition that is indistinguishable from chondrites and is therefore a suitable material for reporting δ49Ti values. Previously published isotope data on another highly refractory element, Ca, show measurable variations among chondrites. The decoupling between Ca and Ti isotope systematics most likely occurred during condensation in the solar nebula. Aubrites exhibit significant variations in δ49Ti, from -0.07 to +0.24‰. This is likely due to the uniquely reducing conditions under which the aubrite parent-body differentiated, allowing chalcophile Ti3+ and lithophile Ti4+ to co-exist. Consequently, the observed negative correlation between δ49Ti values and MgO concentrations among aubrites is interpreted to be the result of isotope fractionation driven by the different oxidation states of Ti in this environment, such that isotopically heavy Ti4+ was concentrated in the residual liquid during magmatic differentiation. Finally, KREEPy impact melt breccia

  18. Igneous Graphite in Enstatite Chondrites

    Science.gov (United States)

    Rubin, Alan E.

    1997-01-01

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

  19. Rare earth abundances in chondritic phosphates and their implications for early stage chronologies

    Energy Technology Data Exchange (ETDEWEB)

    Ebihara, M.; Honda, M. (Tokyo Univ. (Japan). Inst. for Solid State Physics)

    1983-06-01

    The abundances of nine rare earth elements (REE) in phosphate separates from three ordinary chondrites, Saint Severin (LL6), Bruderheim (L6) and Richardton (H5), were measured by instrumental neutron activation analysis. All REE except europium are enriched in the phosphate minerals (merrillite and chlorapatite) by factor of 200-300 relative to the chondritic average, whereas Eu is enriched by a factor of 40-50. Electron microprobe analysis showed no significant differences in phosphate mineral composition among the three chondrites studied, though the relative proportions of two minerals varied. According to our data, REE are enriched by almost the same factor in merrillite and chlorapatite in the Bruderheim and, with less certainty, in the other two chondrites. This behavior of REE contrast with that of the actinoid elements, Th, U and Pu, which are also enriched in phosphate but are fractionated between merrillite and chlorapatite. Since Pu and REE show different fractionation behavior in chondritic phosphates, it may be difficult to use REE as stand-ins for Pu in /sup 244/Pu chronology.

  20. The neodymium stable isotope composition of the silicate Earth and chondrites

    Science.gov (United States)

    McCoy-West, Alex J.; Millet, Marc-Alban; Burton, Kevin W.

    2017-12-01

    The non-chondritic neodymium (Nd) 142Nd/144Nd ratio of the silicate Earth potentially provides a key constraint on the accretion and early evolution of the Earth. Yet, it is debated whether this offset is due to the Earth being formed from material enriched in s-process Nd isotopes or results from an early differentiation process such as the segregation of a late sulfide matte during core formation, collisional erosion or a some combination of these processes. Neodymium stable isotopes are potentially sensitive to early sulfide segregation into Earth's core, a process that cannot be resolved using their radiogenic counterparts. This study presents the first comprehensive Nd stable isotope data for chondritic meteorites and terrestrial rocks. Stable Nd measurements were made using a double spike technique coupled with thermal ionisation mass spectrometry. All three of the major classes of chondritic meteorites, carbonaceous, enstatite and ordinary chondrites have broadly similar isotopic compositions allowing calculation of a chondritic mean of δ146/144Nd = -0.025 ± 0.025‰ (±2 s.d.; n = 39). Enstatite chondrites yield the most uniform stable isotope composition (Δ146/144Nd = 26 ppm), with considerably more variability observed within ordinary (Δ146/144Nd = 72 ppm) and carbonaceous meteorites (Δ146/144Nd = 143 ppm). Terrestrial weathering, nucleosynthetic variations and parent body thermal metamorphism appear to have little measurable effect on δ146/144Nd in chondrites. The small variations observed between ordinary chondrite groups most likely reflect inherited compositional differences between parent bodies, with the larger variations observed in carbonaceous chondrites being linked to varying modal proportions of calcium-aluminium rich inclusions. The terrestrial samples analysed here include rocks ranging from basaltic to rhyolitic in composition, MORB glasses and residual mantle lithologies. All of these terrestrial rocks possess a broadly similar Nd

  1. Formation of unequilibrated R chondrite chondrules and opaque phases

    Science.gov (United States)

    Miller, K. E.; Lauretta, D. S.; Connolly, H. C.; Berger, E. L.; Nagashima, K.; Domanik, K.

    2017-07-01

    Sulfide assemblages are commonly found in chondritic meteorites as small inclusions in the matrix or in association with chondrules. These assemblages are widely hypothesized to form through pre-accretionary corrosion of metal by H2S gas or through parent body processes. We report here on two unequilibrated R chondrite samples that contain large, chondrule-sized sulfide nodules in the matrix. Both samples are from Mount Prestrud (PRE) 95404. Chemical maps and spot and broad-beam electron microprobe analyses (EMPA) were used to assess the distribution, stoichiometry, and bulk composition of sulfide nodules and silicate chondrules in the clasts. Oxygen isotope data were collected via secondary ion mass spectrometry (SIMS) to assess the relationship of chondrules to other chondrite groups. Scanning electron microscopy (SEM), focused ion beam (FIB), and transmission electron microscopy (TEM) analyses were used to assess fine-scale features and identify crystal structures in sulfide assemblages. Thermodynamic models were used to assess the temperature, sulfur fugacity (fS2), total pressure, dust-to-gas ratio, and oxygen fugacity (fO2) conditions during sulfide nodule and chondrule formation. The unequilibrated clasts include a mixture of type I and type II chondrules, as well as non-porphyritic chondrules. Chondrule oxygen isotopes overlap with ordinary-chondrite chondrules. Sulfide nodules average 200 μm in diameter, have rounded shapes, and are primarily composed of pyrrhotite, pentlandite, and magnetite. Some are deformed around chondrules in a petrologic relationship similar in appearance to compound chondrules. Both nodules and sulfides in chondrules include phosphate inclusions and Cu-rich lamellae, which suggests a genetic relationship between sulfides in chondrules and in the matrix. Ni/Co ratios for matrix and chondrule sulfides are solar, while Fe and Ni are non-solar and inversely related. We hypothesize that sulfide nodules formed via pre-accretionary melt

  2. A reappraisal of the metamorphic history of EH3 and EL3 enstatite chondrites

    Science.gov (United States)

    Quirico, Eric; Bourot-denise, Michèle; Robin, Christophe; Montagnac, Gilles; Beck, Pierre

    2011-06-01

    The thermal history of a series of EH3 and EL3 chondrites has been investigated by studying the degree of structural order of the organic matter (OM) located and characterized in matrix areas by Raman micro-spectroscopy. By comparison with unequilibrated ordinary chondrites (UOCs) and CO and CV carbonaceous chondrites, the following petrologic types have been assigned to various E chondrites: Sahara 97096 and Allan Hills 84206: 3.1-3.4; Allan Hills 85170 and Parsa: 3.5; Allan Hills 85119: 3.7; Qingzhen, MacAlpine Hills 88136 and MacAlpine Hills 88184: 3.6-3.7. The petrologic type of Qingzhen is consistent with the abundance of the P3 noble gas component, a sensitive tracer of the grade of thermal metamorphism. The petrologic types are qualitatively consistent with the abundance of fine-grained matrix for the whole series. No significant effects of shock processes on the structure of OM were observed. However such processes certainly compete with thermal metamorphism and the possibility of an effect cannot be fully discarded, in particular in the less metamorphosed objects. The OM precursors accreted by the EH3 and EL3 parent bodies appear to be fairly similar to those of UOCs and CO and CV carbonaceous chondrites. Raman data however show some slight structural differences that could be partly accounted for by shock processes. The metamorphic history of EH3 and EL3 chondrites has often been described as complex, in particular regarding the combined action of shock and thermal metamorphism. Because OM maturity is mostly controlled by the temperature of peak metamorphism, it is possible to distinguish between the contributions of long duration thermal processes and that of shock processes. Comparison of the petrologic types with the closure temperatures previously derived from opaque mineral assemblages has revealed that the thermal history of EH3 and EL3 chondrites is consistent with a simple asteroidal onion shell model. Thermal metamorphism in enstatite chondrites

  3. Micro-Scale Distributions of Major and Trace Elements in Chondrites

    Science.gov (United States)

    Ireland, T. R.; Zolensky, M.

    2011-01-01

    The Hayabusa spacecraft has successfully returned to Earth after two touchdowns on the surface of Asteroid 25143 Itokawa. This asteroid is classified as an S-type and inferred to consist of materials similar to ordinary chondrites or primitive achondrites [1]. More than 1500 particles have been identified consisting of olivine, pyroxene, plagioclase, Fe sulfide and Fe metal, with compositions consistent with being of LL origin. While the chondritic components are familiar to us, the level of detail to which the Itokawa samples will be exposed to will be unprecedented given that the samples are reasonably large and accessible to a wide variety of techniques. In many ways, we expect that our knowledge base of the comparator chondrites will be found to be wanting. Chondrites are the building blocks of the solar system. However, these rocks are essentially breccias and they are quite variable in bulk element compositions as well as compositions of the individual components. We have initiated a program of analysis for chondrites focusing on major and trace element distributions between the mineral components and the matrix. The issues to be addressed include the homogeneity of matrix and chondrule components and the representivity of any given sample to the bulk meteorite. This may be particularly important given the limited numbers of Itokawa grains that may be available for a specific analysis. As an initial study, we have taken thin sections of carbonaceous chondrites to study the representivity of the matrix compositions. Spot locations were constrained to limited regions of the sections so as to assess the variability of a local scale. Further work will be required to assess variability over a centimeter scale.

  4. (TEM) observations of shock damage in the Tenham chondrite

    Science.gov (United States)

    Langenhorst, F.; Joreau, P.; Doukhan, J. C.

    1994-07-01

    Among the ordinary chondrites, the Tenham meteorite (L6) is an instructive example of strong shock metamorphism. It is randomly pervaded by pseudotachylite-like shock veins that contain ringwoodite and majorite, the high-pressure phases of olivine and pyroxene, respectively. According to the revised shock nomenclature of ordinary chondrites, this shock signature is characteristic for shock stage S6 with pressures in excess of 50-55 GPa. In contrast to previous transmission electron microscope (TEM) studies, concentrating on the formation of the high-pressure phases in shock veins, our goal was to characterize the shock defects in olivine, pyroxene, and plagioclase occurring in the bulk of Tenham, i.e., outside shock veins. In olivine, shock has caused the formation of irregular and planar fractures as well as the activation of numerous dislocations. Planar fractures can be either filled with alteration products of Fe-Ni alloy. By far, diopside displays the greatest diversity of shock-induced defects; these are mechanical twins, numerous dislocations, and planar deformation features (PDFs). Diffuse scattering rings in electron diffraction patterns reveal that they consist of amorphous material. In analogy to quartz, it is reasonable to call them PDFs, too. The predominant shock effect in plagioclase is the formation of PDFs. Up to three crossing sets of such parallel, amorphous lamellae have been observed. It is concluded that almost all lattice defects observed in the silicate phases of Tenham are compatible with an impact origin. Some of the defects have been calibrated by shock experiments and, hence, give clues to the shock pressure.

  5. A large shock vein in L chondrite Roosevelt County 106: Evidence for a long-duration shock pulse on the L chondrite parent body

    Science.gov (United States)

    Sharp, Thomas G.; Xie, Zhidong; de Carli, Paul S.; Hu, Jinping

    2015-11-01

    A large shock-induced melt vein in L6 ordinary chondrite Roosevelt County 106 contains abundant high-pressure minerals, including olivine, enstatite, and plagioclase fragments that have been transformed to polycrystalline ringwoodite, majorite, lingunite, and jadeite. The host chondrite at the melt-vein margins contains olivines that are partially transformed to ringwoodite. The quenched silicate melt in the shock veins consists of majoritic garnets, up to 25 μm in size, magnetite, maghemite, and phyllosilicates. The magnetite, maghemite, and phyllosilicates are the terrestrial alteration products of magnesiowüstite and quenched glass. This assemblage indicates crystallization of the silicate melt at approximately 20-25 GPa and 2000 °C. Coarse majorite garnets in the centers of shock veins grade into increasingly finer grained dendritic garnets toward the vein margins, indicating increasing quench rates toward the margins as a result of thermal conduction to the surrounding chondrite host. Nanocrystalline boundary zones, that contain wadsleyite, ringwoodite, majorite, and magnesiowüstite, occur along shock-vein margins. These zones represent rapid quench of a boundary melt that contains less metal-sulfide than the bulk shock vein. One-dimensional finite element heat-flow calculations were performed to estimate a quench time of 750-1900 ms for a 1.6-mm thick shock vein. Because the vein crystallized as a single high-pressure assemblage, the shock pulse duration was at least as long as the quench time and therefore the sample remained at 20-25 GPa for at least 750 ms. This relatively long shock pulse, combined with a modest shock pressure, implies that this sample came from deep in the L chondrite parent body during a collision with a large impacting body, such as the impact event that disrupted the L chondrite parent body 470 Myr ago.

  6. H/L chondrite LaPaz Icefield 031047 - A feather of Icarus?

    Energy Technology Data Exchange (ETDEWEB)

    Wittmann, Axel; Friedrich, Jon M; Troiano, Julianne; Macke, Robert J; Britt, Daniel T; Swidle, Timothy D; Weirich, John R; Rumble, III, Douglas; Lasue, Jeremie; King, David A [Central Florida; (Lunar and Planetary Institute); (CIW); (Ariz); (Fordham); (LANL)

    2011-10-28

    Antarctic meteorite LAP 031047 is an ordinary chondrite composed of loosely consolidated chondritic fragments. Its petrography, oxygen isotopic composition and geochemical inventory are ambiguous and indicate an intermediate character between H and L chondrites. Petrographic indicators suggest LAP 031047 suffered a shock metamorphic overprint below ~10 GPa, which did not destroy its unusually high porosity of ~27 vol%. Metallographic textures in LAP 031047 indicate heating above ~700 °C and subsequent cooling, which caused massive transformation of taenite to kamacite. The depletion of thermally labile trace elements, the crystallization of chondritic glass to microcrystalline plagioclase of unusual composition, and the occurrence of coarsely crystallized chondrule fragments is further evidence for post-metamorphic heating to ~700-750 °C. However, this heating event had a transient character because olivine and low-Ca pyroxene did not equilibrate. Nearly complete degassing up to very high temperatures is indicated by the thorough resetting of LAP 031047's Ar-Ar reservoir ~100 ± 55 Ma ago. A noble gas cosmic-ray exposure age indicates it was reduced to a meter-size fragment at <0.5 Ma. In light of the fact that shock heating cannot account for the thermal history of LAP 031047 in its entirety, we test the hypothesis that this meteorite belonged to the near-surface of an Aten or Apollo asteroid that underwent heating during orbital passages close to the Sun.

  7. H/L chondrite LaPaz Icefield 031047 - A feather of Icarus?

    Science.gov (United States)

    Wittmann, Axel; Friedrich, Jon M.; Troiano, Julianne; Macke, Robert J.; Britt, Daniel T.; Swindle, Timothy D.; Weirich, John R.; Rumble, Douglas; Lasue, Jeremie; Kring, David A.

    2011-10-01

    Antarctic meteorite LAP 031047 is an ordinary chondrite composed of loosely consolidated chondritic fragments. Its petrography, oxygen isotopic composition and geochemical inventory are ambiguous and indicate an intermediate character between H and L chondrites. Petrographic indicators suggest LAP 031047 suffered a shock metamorphic overprint below ˜10 GPa, which did not destroy its unusually high porosity of ˜27 vol%. Metallographic textures in LAP 031047 indicate heating above ˜700 °C and subsequent cooling, which caused massive transformation of taenite to kamacite. The depletion of thermally labile trace elements, the crystallization of chondritic glass to microcrystalline plagioclase of unusual composition, and the occurrence of coarsely crystallized chondrule fragments is further evidence for post-metamorphic heating to ˜700-750 °C. However, this heating event had a transient character because olivine and low-Ca pyroxene did not equilibrate. Nearly complete degassing up to very high temperatures is indicated by the thorough resetting of LAP 031047's Ar-Ar reservoir ˜100 ± 55 Ma ago. A noble gas cosmic-ray exposure age indicates it was reduced to a meter-size fragment at shock heating cannot account for the thermal history of LAP 031047 in its entirety, we test the hypothesis that this meteorite belonged to the near-surface of an Aten or Apollo asteroid that underwent heating during orbital passages close to the Sun.

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

    Science.gov (United States)

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

    1990-06-01

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

  9. Cosmogenic Records in 18 Ordinary Chondrites from the Dar Al Gani Region, Libya. 1; Noble Gases

    Science.gov (United States)

    Schultz, L.; Franke, L.; Welten, K. C.; Nishiizumi, K.; Jull, A. J. T.

    2003-01-01

    In the last decade thousands of meteorites have been recovered from hot deserts in the Sahara and Oman. One of the main meteorite concentration surfaces in the Sahara is the Dar al Gani plateau in Libya, which covers a total area of 8000 km2. More than 1000 meteorites have been reported from this area. The geological setting, meteorite pairings and the meteorite density of the Dar al Gani (DaG) field are described in more detail in [1]. In this work we report concentrations of the noble gas isotopes of He, Ne, Ar as well as 84Kr and 132Xe in 18 DaG meteorites. In a separate paper we will report the cosmogenic radionuclides [2]. We discuss the thermal history and cosmic-ray exposure (CRE) history of these meteorites, and evaluate the effects of the hot desert environment on the noble gas record.

  10. Mineralogical Composition of the Mexican Ordinary Chondrite Type Meteorite: A Raman, Infrared and XRD Study

    Science.gov (United States)

    Ostrooumov, M.

    2016-08-01

    The Raman microprobe (RMP), infrared (IR) and XRD analysis have been applied to the examination of mineralogical composition of seven mexican meteorites: Aldama, Cosina, El Pozo, Escalon, Nuevo Mercurio,Pacula, Zapotitlan Salinas.

  11. Meteorite Jesenice: Mineral and chemical composition of the fusion crust of ordinary chondrite

    Directory of Open Access Journals (Sweden)

    Alenka Lenart

    2010-12-01

    Full Text Available The composition of the well-preserved fusion crust of the meteorite Jesenice was characterised by means ofoptical and scanning electron microscopy (SEM. The SEM investigations revealed three structurally distinct layerswithin the crust. The features of the first layer on the surface are precipitates, enriched in metal elements (iron,nickel, and the partial melting of silicate grains, which continues deeper into the second layer. The second layerbeneath has veins with a heterogeneous composition that indicates a different source of melting minerals. The thirdlayer, which is located deeper within the fusion crust, has not undergone any structural changes and its features aresimilar to the interior of the meteorite. This is additionally confirmed by the presence of cracks, which are a consequenceof shock metamorphism, and irregularly shaped metal and sulphide grains. The structural changes of thethin fusion crust on the surface of this stony meteorite indicate high temperatures (more than 1500 °C accompaniedby high pressures.

  12. Micro-Raman Mapping of Mineral Phases in the Strongly Shocked Taiban Ordinary Chondrite

    Science.gov (United States)

    Acosta, T. E.; Scott, E. R. D.; Sharma, S. K.

    2012-03-01

    Micro-Raman mapping of a thin-section of the highly shocked Taiban meteorite revealed new minor phases around the ringwoodite grains. These phases include wadsleyite and olivine surrounded by pyroxene and majorite.

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

    Science.gov (United States)

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

    Science.gov (United States)

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

    1991-01-01

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

  15. The selenium isotopic variations in chondrites are mass-dependent; Implications for sulfide formation in the early solar system

    Science.gov (United States)

    Labidi, J.; König, S.; Kurzawa, T.; Yierpan, A.; Schoenberg, R.

    2018-01-01

    Element transfer from the solar nebular gas to solids occurred either through direct condensation or via heterogeneous reactions between gaseous molecules and previously condensed solid matter. The precursors of altered sulfides observed in chondrites are for example attributed to reactions between gaseous hydrogen sulfide and metallic iron grains. The transfer of selenium to solids likely occurred through a similar pathway, allowing the formation of iron selenides concomitantly with sulfides. The formation rate of sulfide however remains difficult to assess. Here we investigate whether the Se isotopic composition of meteorites contributes to constrain sulfide formation during condensation stages of our solar system. We present high precision Se concentration and δ 82 / 78 Se data for 23 chondrites as well as the first δ 74 / 78 Se , δ 76 / 78 Se and δ 77 / 78 Se data for a sub-set of seven chondrites. We combine our dataset with previously published sulfur isotopic data and discuss aspects of sulfide formation for various types of chondrites. Our Se concentration data are within uncertainty to literature values and are consistent with sulfides being the dominant selenium host in chondrites. Our overall average δ 82 / 78 Se value for chondrites is - 0.21 ± 0.43 ‰ (n = 23, 2 s.d.), or - 0.14 ± 0.21 ‰ after exclusion of three weathered chondrites (n = 20, 2 s.d.). These average values are within uncertainty indistinguishable from a previously published estimate. For the first time however, we resolve distinct δ 82 / 78 Se between ordinary (- 0.14 ± 0.07 ‰, n = 9, 2 s.d.), enstatite (- 0.27 ± 0.05 ‰, n = 3, 2 s.d.) and CI carbonaceous chondrites (- 0.01 ± 0.06 ‰, n = 2, 2 s.d.). We also resolve a Se isotopic variability among CM carbonaceous chondrites. In addition, we report on δ 74 / 78 Se , δ 76 / 78 Se and δ 77 / 78 Se values determined for 7 chondrites. Our data allow evaluating the mass dependency of the δ 82 / 78 Se variations. Mass

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

    Science.gov (United States)

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

    2014-07-01

    to evaluate the metamorphic grade of the objects and to assign a petrologic type along a unique petrologic scale [1-4]. This technique has been successfully applied to type 3 Unequilibrated Ordinary Chondrites [1], carbonaceous CV chondrites [2], and CO chondrites [3]. The interpretation of the structural order of the polyaromatic carbonaceous matter in terms of thermal history is thus reliable. Raman spectroscopy enables the determination of the degree of structural order of the polyaromatic organic matter present in the matrix of chondrites. Both falls and finds, from Antarctica [4] and elsewhere, have been analyzed. It does not require a large amount of samples and is relatively easy to implement. Raman spectroscopy is particularly sensitive to the lowest petrologic types (3.0-3.2). The present NASA collection of Antarctic meteorites represents an incredible source of precious samples for our community. The present work finely characterizes the thermal history of most of the type 3 chondrites (UOCs, CVs, and COs) from that collection. At the present time, the objectives are threefold: (i) determination of reliable petrologic types indispensable for our community; (ii) identification of the most primitive type 3 chondrites (petrologic type ≤ 3.1); and (iii) identification of potential ''anomalous'' samples having experienced a slightly different thermal history. The JSC Meteorite Working Group generously allocated us with more than 150 chondrites (UOCs, CVs, and COs). The following points summarize the main results. (i) At the present time, the thermal histories of more than 100 samples have been characterized. (ii) The terrestrial weathering experienced by several chondrites (˜25 chondrites) has been too pervasive for the method to be applied. For these meteorites, as signatures of oxide minerals dominate Raman spectra of the matrix, the organic matter might have been significantly altered through oxidation. (iii) Real discrepancies with the preliminary JSC

  17. Water in type I chondrules of Paris CM chondrite

    Science.gov (United States)

    Stephant, A.; Remusat, L.; Robert, F.

    2017-02-01

    Hydrogen isotopic ratio and water concentration have been measured with the NanoSIMS in olivine, pyroxene and mesostasis in individual chondrules from the carbonaceous chondrites Paris (CM2), Renazzo (CR2) and ordinary chondrite Bishunpur (LL3). On average, chondrule pyroxenes in Renazzo, Bishunpur and Paris contain 893 ± 637 ppm (1SD), 879 ± 536 ppm and 791 ± 227 ppm H2O, respectively. Concentration of H2O in Chondrule olivines from Renazzo and Bishunpur is 156 ± 44 ppm and 222 ± 123 ppm, respectively. Olivines in the Paris chondrules have high water concentration (603 ± 145-1051 ± 253 ppm H2O) with a minimum mean value of 645 ± 99 ppm. δD ranges from -212 ± 125‰ to 15 ± 156‰ and from -166 ± 133‰ to 137 ± 176‰ in Renazzo and Bishunpur chondrule olivines, pyroxenes and mesostases, respectively. In Paris chondrules, δD ranges from -398 ± 23‰ to 366 ± 35‰; this represents an extreme variation over 764‰. Paris olivines and pyroxenes are either enriched or depleted in deuterium relative to the mesostasis and no systematic isotopic pattern is observed. Simple model of chondrules hydration during parent body hydrothermal alteration is difficult to reconcile with such isotopic heterogeneity. It is proposed that a hydrous component, having a δD of c.a. -400‰, in the chondrule precursors, has been outgassed at 800-900 °C in the gas phase. Nevertheless, a residual water fraction remains trapped in Paris chondrules. Quantitative modeling supports this scenario.

  18. Equivariant ordinary homology and cohomology

    CERN Document Server

    Costenoble, Steven R

    2016-01-01

    Filling a gap in the literature, this book takes the reader to the frontiers of equivariant topology, the study of objects with specified symmetries. The discussion is motivated by reference to a list of instructive “toy” examples and calculations in what is a relatively unexplored field. The authors also provide a reading path for the first-time reader less interested in working through sophisticated machinery but still desiring a rigorous understanding of the main concepts. The subject’s classical counterparts, ordinary homology and cohomology, dating back to the work of Henri Poincaré in topology, are calculational and theoretical tools which are important in many parts of mathematics and theoretical physics, particularly in the study of manifolds. Similarly powerful tools have been lacking, however, in the context of equivariant topology. Aimed at advanced graduate students and researchers in algebraic topology and related fields, the book assumes knowledge of basic algebraic topology and group act...

  19. Bob Dylan, the Ordinary Star

    Directory of Open Access Journals (Sweden)

    Laure Bouquerel

    2007-03-01

    Full Text Available This article provides a study of Bob Dylan’s public image as a “star” performer and examines what Dylan represented for his audiences with respect to the challenges of 1960s counterculture. This study focuses primarily on the image of Dylan in D. A. Pennebaker’s documentary film Don’t Look Back, which portrays Dylan when the star is only 23. A study of Pennebaker’s film shows how the filmmaker captures the paradox of Dylan’s star popularity in his refusal to portray the star, not only as a personal struggle, but as a cultural contradiction. The author further identifies a formal link between Dylan’s portrayal of the ordinary star and the minimalist aesthetic of cinéma vérité.

  20. Quantum States as Ordinary Information

    Directory of Open Access Journals (Sweden)

    Ken Wharton

    2014-03-01

    Full Text Available Despite various parallels between quantum states and ordinary information, quantum no-go-theorems have convinced many that there is no realistic framework that might underly quantum theory, no reality that quantum states can represent knowledge about. This paper develops the case that there is a plausible underlying reality: one actual spacetime-based history, although with behavior that appears strange when analyzed dynamically (one time-slice at a time. By using a simple model with no dynamical laws, it becomes evident that this behavior is actually quite natural when analyzed “all-at-once” (as in classical action principles. From this perspective, traditional quantum states would represent incomplete information about possible spacetime histories, conditional on the future measurement geometry. Without dynamical laws imposing additional restrictions, those histories can have a classical probability distribution, where exactly one history can be said to represent an underlying reality.

  1. Shock Metamorphism in L Chondrites Above Shock Stage S6

    Science.gov (United States)

    Hu, J.; Sharp, T. G.; De Carli, P. S.

    2013-09-01

    We investigated several L6 chondrites shocked to between stage S6 and whole rock melting. The study presents the effects of high post-shock temperature and the annealing of high-pressure evidence in highly shocked chondrites.

  2. 146Sm-142Nd systematics measured in enstatite chondrites reveals a heterogeneous distribution of 142Nd in the solar nebula.

    Science.gov (United States)

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

    2011-05-10

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

  3. Early Solar System hydrothermal activity in chondritic asteroids on 1-10-year timescales.

    Science.gov (United States)

    Dyl, Kathryn A; Bischoff, Addi; Ziegler, Karen; Young, Edward D; Wimmer, Karl; Bland, Phil A

    2012-11-06

    Chondritic meteorites are considered the most primitive remnants of planetesimals from the early Solar System. As undifferentiated objects, they also display widespread evidence of water-rock interaction on the parent body. Understanding this history has implications for the formation of planetary bodies, the delivery of water to the inner Solar System, and the formation of prebiotic molecules. The timescales of water-rock reactions in these early objects, however, are largely unknown. Here, we report evidence for short-lived water-rock reactions in the highly metamorphosed ordinary chondrite breccia Villalbeto de la Peña (L6). An exotic clast (d = 2cm) has coexisting variations in feldspar composition and oxygen isotope ratios that can only result from hydrothermal conditions. The profiles were modeled at T = 800 °C and P(H(2)O) = 1 bar using modified grain-boundary diffusion parameters for oxygen self-diffusion and reaction rates of NaSiCa(-1)Al(-1) exchange in a fumarole. The geochemical data are consistent with hydrothermal activity on the parent body lasting only 1-10 y. This result has wide-ranging implications for the geological history of chondritic asteroids.

  4. Early Solar System hydrothermal activity in chondritic asteroids on 1–10-year timescales

    Science.gov (United States)

    Dyl, Kathryn A.; Bischoff, Addi; Ziegler, Karen; Young, Edward D.; Wimmer, Karl; Bland, Phil A.

    2012-01-01

    Chondritic meteorites are considered the most primitive remnants of planetesimals from the early Solar System. As undifferentiated objects, they also display widespread evidence of water–rock interaction on the parent body. Understanding this history has implications for the formation of planetary bodies, the delivery of water to the inner Solar System, and the formation of prebiotic molecules. The timescales of water–rock reactions in these early objects, however, are largely unknown. Here, we report evidence for short-lived water–rock reactions in the highly metamorphosed ordinary chondrite breccia Villalbeto de la Peña (L6). An exotic clast (d = 2cm) has coexisting variations in feldspar composition and oxygen isotope ratios that can only result from hydrothermal conditions. The profiles were modeled at T = 800 °C and P(H2O) = 1 bar using modified grain-boundary diffusion parameters for oxygen self-diffusion and reaction rates of NaSiCa-1Al-1 exchange in a fumarole. The geochemical data are consistent with hydrothermal activity on the parent body lasting only 1–10 y. This result has wide-ranging implications for the geological history of chondritic asteroids. PMID:23093668

  5. Degree of Weathering of H-Chondrites From Frontier Mountain, Antarctica

    Science.gov (United States)

    Welten, K. C.; Nishiizumi, K.

    2000-01-01

    One of the factors that determines the survival time of meteorites on the Earth's surface is the rate of weathering. For meteorites from hot deserts, a clear correlation is found between the degree of weathering, and the terrestrial age, but for Antarctic meteorites this correlation is weak or even lacking. The lack of a clear correlation can partly be attributed to the two-stage history of many Antarctic meteorites, which spend part of their terrestrial residence time in the ice before they are exposed on the ice. Recently, it was found that for Lewis Cliff (LEW) meteorites local conditions on the ice play an important role in the weathering process. This work focuses on weathering effects in ordinary chondrites from Frontier Mountain (FRO), North Victoria Land. Although most FRO meteorites were classified as weathering category A or B, many are contaminated with terrestrial uranium, deposited from meltwater. This suggests that weathering plays a more significant role than the qualitative A-B-C weathering index indicates. We therefore determined the degree of weathering more quantitatively, by deriving the amount of oxidized metal from the concentrations of Fe and Ni in the nonmagnetic fraction of 23 H-chondrites and 1 L-chondrite The results will be compared with those of LEW meteorites and will be discussed in terms of terrestrial age and location of find on the ice.

  6. Experimental partial melting of the St. Severin (LL) and Lost City (H) chondrites

    Science.gov (United States)

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

    1995-01-01

    We have performed melting experiments between 1170-1325°C and at an oxygen fugacity of IW-1 on the ordinary chondrites Lost City (H) and St. Severin (LL) in order to investigate the origin of diogenites and their possible relationship to eucrites. Low-Ca pyroxene disappears from the Lost City residuum just above 1220°C at a Mg# near 66. Accordingly, Lost City does not have a sufficiently large stability field for orthopyroxene to be a likely parent composition for melts which could crystallize diogenites. In contrast, orthopyroxene in St. Severin persists up to about 1325°C, at which point it has a Mg# similar to that of typical diogenites (˜75). This is only marginally compatible with diogenite origins, as the most magnesian pyroxenes from diogenites (Mg# 82) and howardites (Mg# 85) are more MgO-rich than any pyroxene formed from a St. Severin melt. Accordingly, if diogenites formed from a source having the bulk composition of an ordinary chondrite, than either the fO 2 had to be lower than that inferred for eucrite formation or, more likely, the parent body had a lower Fe/Si ratio than that of an LL chondrite. Also, low temperature melts of St. Severin are depleted in elements compatible with pyroxene and so, while broadly eucritic, do not closely match the compositions of eucrites that are thought to be primary partial melts. Hence, it doesn't appear possible to produce both diogenites and eucrites from the same source region composition, if eucrites are primary partial melts. Reconnaiss:mce experiments at higher oxygen fugacity (IW + 2) produce broadly angritic melts for Lost City, as was observed for Murchison and Allende. In contrast, our Na 2O-poor St. Severin charge produced a broadly eucritic melt at this higher fO 2 This difference in melting behavior is probably because LL chondrites have a much lower bulk Fe/Si ratio than the H, CM, or CV chondrites.

  7. Extraterrestrial Nucleobases in Carbonaceous Chondrites

    Science.gov (United States)

    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

  8. Experimental vaporization of the Holbrook chondrite

    Science.gov (United States)

    Gooding, J. L.; Muenow, D. W.

    1977-01-01

    The vapor phase composition obtained by heating samples of the Holbrook L6 chondrite to 1300 C was determined quantitatively by Knudsen cell-quadrupole mass spectrometry. Maximum observed vapor pressures, produced at 1200 C, are reported for Na, K, Fe, and Ni, and the implications of the Na/K ratio are considered. The Fe and Ni data are discussed with attention to their migration in individual equilibrated chondrites. S2 (with minor SO2), H2O, and CO2 were also present in the high-temperature gas phase. Vesicles formed by the release of intrinsically derived volatiles are compared with vesicles in the Ibitira eucrite. Chondrite evolution is briefly discussed.

  9. Petrology and Stable Isotopes of LEW 87232, A New Kakangari-type Chondrite

    Science.gov (United States)

    Weisberg, M. K.; Prinz, M.; Clayton, R. N.; Mayeda, T. K.; Grady, M. M.; Franchi, I. A.

    1993-07-01

    closest to that of ordinary chondrites and differs from that of Kakangari, which has lighter N (total delta-15N = -20 permil). Total [C] = 1989 ppm and is also closest to ordinary chondrites. Kakangari total [C] = 864 [10]. Combustion temperatures indicate the presence of some organic component with delta-15N ~ +4 to +8 permil released at low T. N released above 1000 degrees C may be a combination of spallogenic N, with N possibly from SiC. The oxygen isotope compositions of Kakangari-type chondrites are shown in the figure. Whole rock LEW87232 plots close to the other Kakangari-type chondrites. Chondrule compositions are similar to those in Kakangari, but are displaced toward lower delta-18O values perhaps, in part, due to weathering. Chondrules from Kakangari-type chondrites generally have oxygen compositions similar to enstatite chondrite chondrules (shown by the loop) and some extend toward more 16O-rich compositions. Conclusions: LEW87232 is shown to be a Kakangari-type meteorite and it further defines this distinct chondrite grouplet. Characteristics that distinguish the Kakangari-type grouplet from other chondrite groups include (1) the oxygen isotope composition of the chondrules and matrix, (2) the high metal and pyroxene abundances and low FeO content of the silicates that indicate an oxidation state between H and E chondrites, (3) the Mg- and pyroxene-rich nature and similarity of the chondrules and matrix, (4) the unique intergrowths of matrix pyroxene within and rimming metal chondrules, suggesting that abundant Mg-rich pyroxene crystals formed in the nebula and were present during chondrule formation. References: [1] Mason B. (1992) Ant. Met. News., 15, 24. [2] Weisberg M. K. et al. (1993) GCA, 57, 1567-1586. [3] Graham A. L. and Hutchison R. (1974) Nature, 251, 128-129. [4] Clayton R. N. et al. (1976) LPSC, VII, 160-162. [5] Clayton R. N. et al. (1976) EPSL, 30, 10-18. [6] Davis A. M. et al. (1977) Nature, 265, 230-232. [7] Prinz M. et al. (1989) LPSC, XX

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

    Science.gov (United States)

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

    2006-01-01

    reflect their lithified nature and low surface/volume ratios during the period when they resided in the regolith and were subject to irradiation by solar particles. The clasts are analogous to the light-colored metamorphosed clasts in ordinary-chondrite regolith breccias (which also lack solar-flare particle tracks and solar-wind gas).

  11. Oxygen isotope characteristics of chondrules from the Yamato-82094 ungrouped carbonaceous chondrite: Further evidence for common O-isotope environments sampled among carbonaceous chondrites

    Science.gov (United States)

    Tenner, T. J.; Kimura, M.; Kita, N. T.

    2017-02-01

    High-precision secondary ion mass spectrometry (SIMS) was employed to investigate oxygen three isotopes of phenocrysts in 35 chondrules from the Yamato (Y) 82094 ungrouped 3.2 carbonaceous chondrite. Twenty-one of 21 chondrules have multiple homogeneous pyroxene data (∆17O 3SD analytical uncertainty: 0.7‰); 17 of 17 chondrules have multiple homogeneous pyroxene and plagioclase data. Twenty-one of 25 chondrules have one or more olivine data matching coexisting pyroxene data. Such homogeneous phenocrysts (1) are interpreted to have crystallized from the final chondrule melt, defining host O-isotope ratios; and (2) suggest efficient O-isotope exchange between ambient gas and chondrule melt during formation. Host values plot within 0.7‰ of the primitive chondrule mineral (PCM) line. Seventeen chondrules have relict olivine and/or spinel, with some δ17O and δ18O values approaching -40‰, similar to CAI or AOA-like precursors. Regarding host chondrule data, 22 of 34 have Mg#s of 98.8-99.5 and ∆17O of -3.9‰ to -6.1‰, consistent with most Acfer 094, CO, CR, and CV chondrite chondrules, and suggesting a common reduced O-isotope reservoir devoid of 16O-poor H2O. Six Y-82094 chondrules have ∆17O near -2.5‰, with Mg#s of 64-97, consistent with lower Mg# chondrules from Acfer 094, CO, CR, and CV chondrites; their signatures suggest precursors consisting of those forming Mg# 99, ∆17O: -5‰ ± 1‰ chondrules plus 16O-poor H2O, at high dust enrichments. Three type II chondrules plot slightly above the PCM line, near the terrestrial fractionation line (∆17O: +0.1‰). Their O-isotopes and olivine chemistry are like LL3 type II chondrules, suggesting they sampled ordinary chondrite-like chondrule precursors. Finally, three Mg# >99 chondrules have ∆17O of -6.7‰ to -8.1‰, potentially due to 16O-rich refractory precursor components. The predominance of Mg# 99, ∆17O: -5‰ ± 1‰ chondrules and a high chondrule-to-matrix ratio suggests bulk Y-82094

  12. Collision condition indicted by High Pressure Phases in a Chondrite

    Science.gov (United States)

    Kato, Y.; Sekine, T.; Kayama, M.; Miyahara, M.; Yamaguchi, A.

    2012-12-01

    It has been generally recognized that there were many collisions during planetary accretion. Chondrites include the materials at the time of formation of the solar system. It is essential to unravel the shock history in meteorites and the parent planet in order to understand such collisional processes. In this study, we investigate a thin section of ordinary chondrite Y-790729 classified as L6 in which high-pressure minerals are found in the about 620-μm-wide shock vein. The mineralogical and chemical features give us detailed information to constrain the shock conditions. We have tried to constrain the P-T condition from the viewpoints of the mineral assemblage and cathodoluminescense (CL) spectroscopy. Y-790729 consists mostly of olivine and pyroxene and has shock veins. To identify high pressure phases, we used an optical microscope, a scanning electron microscope (SEM), micro Raman spectroscopy, and electron probe micro analyzer (EPMA). In addition, scanning electron microscopy-cathodoluminescence (SEM-CL) analysis, detectable shock-induced defect centers, was used to characterize the shock metamorphism in feldspar minerals. The presence of shock vein, maskelynite, and high pressure phases confirms shock record. 7 high pressure phases of ringwoodite, high-pressure clinoenstatite (HPC), majorite, merrillite, lingunite, high-pressure chromite and akimotoite were found in this section. All of them exist only in a shock vein, but maskelynite occurs everywhere in the section. From these observations, it is obvious that the shock vein experienced the high pressure and high temperature generated by shock wave. If some of the high pressure minerals are equilibrated, the P-T condition can be estimated. Based on the equilibrium phase diagram of MgSiO3 polymorphs (Presnall. 1995), the P-T conditions for crystallization of majorite, HPC and akimotoite is about 17 GPa and 1600 oC, because the compositions of the three phases are close to MgSiO3. It is consistent with the

  13. The Buritizal meteorite: classification of a new Brazilian chondrite

    Directory of Open Access Journals (Sweden)

    Rogerio Nogueira Salaverry

    Full Text Available Abstract On August 14, 1967, the reporter Saulo Gomes, working at TV Tupi, went to a small city in the State of São Paulo called Buritizal to investigate reports of a meteorite fall and write a newspaper report. He actually recovered three fragments of the meteorite at a small farm. In 2014, he donated one of the fragments to the Museu Nacional of the Universidade Federal do Rio de Janeiro (MN/UFRJ. We named this meteorite Buritizal and studied its petrology, geochemistry, magnetic properties and cathodoluminescence with the intent to determine the petrologic classification of the meteorite. In this manner, the Buritizal meteorite is classified as an ordinary chondrite LL 3.2 breccia (as indicated by lithic fragments. The meteorite consists of ~ 2% of metallic Fe,Ni and many well-defined chondrules with ~ 0.8 mm in average diameter. An ultramafic ferromagnesian mineralogy is predominant in the meteorite, represented by olivine, orthopyroxene, clinopyroxene, Fe-Ni alloy, troilite and glass. The total iron content was calculated as 20.88 wt%. Furthermore, the meteorite was classified as weathering grade W1 and shock stage S3. Buritizal is the 25th observed meteorite fall recovered in Brazil, of 70 meteorites known from Brazil. Thus, the study of the Buritizal meteorite is very important and relevant for the Brazilian scientific community.

  14. Occurrence of Whitlockite in Chondritic Meteorites.

    Science.gov (United States)

    Fuchs, L H

    1962-08-10

    The first reported occurrence of the tricalcium phosphate mineral, whitlockite, in several chondrites is described. The identification of this mineral and previously reported chlorapatite were made by x-ray diffraction; the results do not confirm the postulated existence of meteoritic merrillite. Some other remarks pertaining to the existence of merrillite are presented.

  15. Experimental Data in Support of the 1991 Shock Classification of Chondrites

    Science.gov (United States)

    Schmitt, R. T.; Stoffler, D.

    1995-09-01

    We present results of shock recovery experiments performed on the H6(S1) chondrite Kernouv . These data and new observations on ordinary chondrites confirm the recently proposed classification system [1] and provide additional criteria for determining the shock stage, the shock pressure, and, under certain conditions, also the ambient (pre-shock) temperature during shock metamorphism of any chondrite sample. Two series of experiments at 293 K and 920 K and 10, 15, 20, 25, 30, 45, and 60 GPa were made with a high explosive device [2] using 0.5 mm thick disks of the Kernouv chondrite. Shock effects in olivine, orthopyroxene, plagioclase, and troilite and shock-induced melt products were studied by optical [3], electron optical and X-ray diffraction methods. All essential characteristics of the six progressive stages of shock metamorphism (S1 - S6) observed in natural samples of chondrites [1] have been reproduced experimentally except for opaque shock veins and the high pressure polymorphs of olivine and pyroxene (ringwoodite/wadsleyite and majorite), well known from naturally shocked chondrites. This is probably due to the special sample and containment geometry and the extremely short pressure pulses (0.2 - 0.8 microseconds) in the experiments. The shock experiments provided a clear understanding of the shock wave behavior of troilite and of the shock-induced melting, mobilization, and exsolution-recrystallization of composite troilite-metal grains. At 293 K troilite is monocrystalline up to 35 GPa displaying undulatory extinction from 10 to 25 GPa, partial recrystallization from 30 - 45 GPa, and complete recrystallization above 45 GPa. Local melting of troilite/metal grains starts at 30 GPa and composite grains displaying exsolution textures of both phases are formed which get mobilized and deposited into fractures of neighbouring silicate grains above 45 GPa. For a pre-shock temperature of 293 K the pressure at which diagnostic shock effects are formed, is

  16. Chondrites and the Protoplanetary Disk, Part 3

    Science.gov (United States)

    2004-01-01

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

  17. Ordinary Stoichiometry of Extraordinary Microbes

    Science.gov (United States)

    Neveu, M.; Poret-Peterson, A. T.; Anbar, A. D.; Elser, J. J.

    2013-12-01

    commonly observed in temperate lakes (e.g., C:P ratios of 260 to 1600 and N:P ratios of 35 to 200) while cellular C:Fe ratios were of a similar magnitude to those of marine phytoplankton. Exceptions were Al and Ti, much higher than previously measured, likely because of contamination from residual sediment. Moreover, the low phosphorus contents (high C:P and N:P ratios) are suggestive of limited P supply. Chemotrophs and phototrophs had similar elemental compositions to one another, although Mg, Mn, Ni, and Zn abundances were higher and nearly constant in phototrophs, due to their importance in phototrophic metabolism. Despite the tremendous physical and chemical diversity of YNP environments, the stoichiometry of life in these settings is surprisingly ordinary. Thus, our study supports the view that the biological stoichiometry of life is heavily constrained by the elemental composition of core biomolecules, and that even life in extreme environments must operate within these constraints. In the frame of life detection in exotic locales, these results suggest a general elemental biosignature for life as we know it. References: [1] Amalfitano and Fazi. 2008. J. Microbiol. Meth. 75:237 [2] Neveu et al. L&O: Meth., in review [3] Ho et al. 2003. J. Phycol. 39:1145 [4] Nuester et al. 2012. Front. Microbiol. 3:150 [5] Sterner and Elser. 2002. Ecological Stoichiometry. Princeton U. Press [6] Twining et al. 2011. Deep-Sea Res. II 58:325

  18. Deducing Wild 2 Components with a Statistical Dataset of Olivine in Chondrite Matrix

    Science.gov (United States)

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

    2012-01-01

    , Wild 2 may have received a larger contribution from the Kakangari and/or enstatite chondrite forming regions. Alternatively, Wild 2 may have undergone accretion in an anomalously reducing region, marked by nebular condensation of this atypical forsterite. In [4], a similar conclusion was reached with an Fe-XANES study. We will also use similar lines of reasoning, and our previous conclusions in [5], to constrain the relative contributions of silicates that appear to have been radially transported from different ordinary and carbonaceous chondrite forming regions to the Kuiper Belt. In addition, the widespread depletion of Cr in these FeO-rich (Fa(sub greater than 20)) fragments is consistent with mild thermal metamorphism in Wild 2.

  19. Petrographic shock indicators and noble gas signatures in a H and an L chondrite from Antarctica

    Science.gov (United States)

    Ranjith, P. M.; He, Huaiyu; Miao, Bingkui; Su, Fei; Zhang, Chuantong; Xia, Zhipeng; Xie, Lanfang; Zhu, Rixiang

    2017-10-01

    Petrographic shock indicators and noble gas signatures are studied in two ordinary chondrites, Grove Mountain (GRV) 13083 (H4) and GRV 13095 (L5), from Antarctica to investigate the degree of shock metamorphism and impact related chronologies on H and L chondrite parent bodies. In the study, we have combined both noble gas signatures and petrographic observations to understand impact effects. Based on the impact features in silicates and metal-troilite assemblages, the shock stages of the samples are classified as S6 and S5 for GRV 13095 (L5) and GRV 13083 (H4) respectively. The nominal K-Ar gas retention age of GRV 13095 (L5, S6) using bulk sample is estimated as 459 ± 13 Ma, supporting the recent major catastrophic break up event at 470 Ma on the L-chondrite parent body. The cosmic ray exposure age based on He, Ne and Ar noble gas measurements is estimated as 14.1 ± 2.5 Ma. The radiogenic gas contents in GRV 13095 (avg. 4He = 61.5 × 10-8 ccSTP/g and avg. 40Ar = 173.5 × 10-8 ccSTP/g) are observed as depleted. The depletion in radiogenic gases is consistent with the severe shock metamorphism in GRV 13095 as indicated by olivine-ringwoodite transformation in it. The estimated nominal K-Ar age of 3.67 ± 0.26 Ga for GRV 13083 shows that it falls in the major impact age distribution between 3.5 and 4.0 Ga among H-chondrites. The cosmic ray exposure age of GRV 13083 is 3.9 ± 0.7 Ma, which is younger than the major peak in the exposure age distribution for H-chondrites. The He gas retention ages in both samples are found to be younger/lower than their respective nominal K-Ar ages, which could be due to partial loss of radiogenic He. Trapped gas loss along with radiogenic gas losses in both samples, are the adverse effects of shock metamorphism.

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

    Science.gov (United States)

    Nozette, S.

    1979-01-01

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

  1. FILSAFAT ORDINARY LANGUAGE DAN PEMBELAJARAN BAHASA

    OpenAIRE

    NURLAILA NURLAILA

    2016-01-01

    Ordinary language philosophy was one of the streams of analical language philosophies that had layed on how language was used. This became basic principle in studying pragmatic in lingusitic study. The idea of ordinary language about the pragmatic approach in learning language oriented to create the students’ communication ability that was appropriate with the context where the communication happened. It was because learning language means leaning communication and language as a tool of commu...

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

    Science.gov (United States)

    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

  3. Ca-Al-Fe-rich inclusion in the Vigarano CV3 chondrite

    Science.gov (United States)

    Maruyama, Seiji; Tomioka, Naotaka

    2011-05-01

    An anomalous Ca-Al-Fe-rich spherical inclusion (CAFI) was found in the Vigarano CV3 chondrite. The CAFI has an igneous texture and contains large amounts of almost pure and coarse-grained hercynite grains (approximately 56 vol%) as well as refractory phases such as grossite and perovskite. However, melilite and Mg-spinel, which are common in ordinary Ca-Al-rich inclusions, are very rare (shock metamorphism of a low-pressure form of CaAl2O4 that was originally crystallized from a molten droplet. The fine-grained hercynite and unidentified aluminous phase in the rim of the CAFI may have been produced from grossite during aqueous alteration in the Vigarano parent body.

  4. Oxygen Isotope Compositions of the Kaidun Meteorite - Indications for Aqeuous Alteration of E-Chondrites

    Science.gov (United States)

    Ziegler, K.; Zolensky, M.; Young, E. D.; Ivanov, A.

    2012-01-01

    The Kaidun microbreccia is a unique meteorite due to the diversity of its constituent clasts. Fragments of various types of carbonaceous (CI, CM, CV, CR), enstatite (EH, EL), and ordinary chondrites, basaltic achondrites, and impact melt products have been described, and also several unknown clasts [1, and references therein]. The small mm-sized clasts represent material from different places and times in the early solar system, involving a large variety of parent bodies [2]; meteorites are of key importance to the study of the origin and evolution of the solar system, and Kaidun is a collection of a range of bodies evidently representing samples from across the asteroid belt. The parent-body on which Kaidun was assembled is believed to be a C-type asteroid, and 1-Ceres and the martian moon Phobos have been proposed [1-4]. Both carbonaceous (most oxidized) and enstatite (most reduced) chondrite clasts in Kaidun show signs of aqueous alterations that vary in type and degree and are most likely of pre-Kaidun origin [1, 4].

  5. Mineral and chemical composition of the Jezersko meteorite—A new chondrite from Slovenia

    Science.gov (United States)

    Miler, Miloš; Ambrožič, Bojan; Mirtič, Breda; Gosar, Mateja; Å turm, Sašo.; Dolenec, Matej; Jeršek, Miha

    2014-10-01

    The Jezersko meteorite is a newly confirmed stony meteorite found in 1992 in the Karavanke mountains, Slovenia. The meteorite is moderately weathered (W2), indicating short terrestrial residence time. Chondrules in partially recrystallized matrix are clearly discernible but often fragmented and have mean diameter of 0.73 mm. The meteorite consists of homogeneous olivine (Fa19.4) and low-Ca pyroxenes (Fs16.7Wo1.2), of which 34% are monoclinic, and minor plagioclase (Ab83An11Or6) and Ca-pyroxene (Fs6Wo45.8). Troilite, kamacite, zoned taenite, tetrataenite, chromite, and metallic copper comprise about 16.5 vol% of the meteorite. Phosphates are represented by merrillite and minor chlorapatite. Undulatory extinction in some olivine grains and other shock indicators suggests weak shock metamorphism between stages S2 and S3. The bulk chemical composition generally corresponds to the mean H chondrite composition. Low siderophile element contents indicate the oxidized character of the Jezersko parent body. The temperatures recorded by two-pyroxene, olivine-chromite, and olivine-orthopyroxene geothermometers are 854 °C, 737-787 °C, and 750 °C, respectively. Mg concentration profiles across orthopyroxenes and clinopyroxenes indicate relatively fast cooling at temperatures above 700 °C. A low cooling rate of 10 °C Myr-1 was obtained from metallographic data. Considering physical, chemical, and mineralogical properties, meteorite Jezersko was classified as an H4 S2(3) ordinary chondrite.

  6. Analyzing the Chemical and Spectral Effects of Pulsed Laser Irradiation to Simulate Space Weathering of a Carbonaceous Chondrite

    Science.gov (United States)

    Thompson, M. S.; Keller, L. P.; Christoffersen, R.; Loeffler, M. J.; Morris, R. V.; Graff, T. G.; Rahman, Z.

    2017-01-01

    Space weathering processes alter the chemical composition, microstructure, and spectral characteristics of material on the surfaces of airless bodies. The mechanisms driving space weathering include solar wind irradiation and the melting, vaporization and recondensation effects associated with micrometeorite impacts e.g., [1]. While much work has been done to understand space weathering of lunar and ordinary chondritic materials, the effects of these processes on hydrated carbonaceous chondrites is poorly understood. Analysis of space weathering of carbonaceous materials will be critical for understanding the nature of samples returned by upcoming missions targeting primitive, organic-rich bodies (e.g., OSIRIS-REx and Hayabusa 2). Recent experiments have shown the spectral properties of carbonaceous materials and associated minerals are altered by simulated weathering events e.g., [2-5]. However, the resulting type of alteration i.e., reddening vs. bluing of the reflectance spectrum, is not consistent across all experiments [2-5]. In addition, the microstructural and crystal chemical effects of many of these experiments have not been well characterized, making it difficult to attribute spectral changes to specific mineralogical or chemical changes in the samples. Here we report results of a pulsed laser irradiation experiment on a chip of the Murchison CM2 carbonaceous chondrite to simulate micrometeorite impact processing.

  7. Thermal metamorphism of primitive meteorites. VII - Mineralogy-petrology of heated Murchison /C2/ and alteration of C30 and other chondrites

    Science.gov (United States)

    Matza, S. D.; Lipschutz, M. E.

    1978-01-01

    Alterations caused by week-long heating of Murchison in a low-pressure environment at 400-1400 C are of two types: thermodynamically favored kinetically controlled or thermodynamically controlled rapid processes. Kinetically controlled changes pertinent to chondritic evolution and which vary progressively with temperature in heated Murchison include: chondrule blurring; matrix coarsening; increasing mean Fa and Fs contents of ferromagnesian silicates; equilibration of olivine; increasing Mg/Si, Ca/Si, Al/Si, and Cr/Si and decreasing Fe/Si, Ni/Si, and S/Si in matrix; Cr loss from kamacite; and homogenization and Ni-zoning in taenite at high temperatures. Low-temperature thermodynamically controlled changes include: transformation of high-Ni troilite to low-Ni and formation of Ni- and Co-rich metal from pentlandite. High-temperature changes include formation of Cr-rich magnetite and formation of a Ni-rich sulfide similar to that found in highly altered chondrites. Trends resulting from processes of both kinds in Murchison are consistent with characteristics of a postulated C30 metamorphic suite, while those changes caused by reactions of the second kind are similar to those in heavily shock-heated ordinary chondrites and the heavily metamorphosed C5-6 chondrite, Mulga West. Either the simulations support the metamorphic origin of the C30 suite and other thermally induced changes or the natural alterations support the utility of laboratory simulations in studying meteoritic evolution.

  8. Symmetries of nonlinear ordinary differential equations: The ...

    Indian Academy of Sciences (India)

    2015-10-21

    Oct 21, 2015 ... Lie symmetry analysis is one of the powerful tools to analyse nonlinear ordinary dif- ferential equations. We review the effectiveness of this method in terms of various symmetries. We present the method .... coincides with the linearized equation, then the underlying system is self-adjoint and in this case the ...

  9. Symmetries of nonlinear ordinary differential equations: The ...

    Indian Academy of Sciences (India)

    2015-10-21

    Oct 21, 2015 ... Lie symmetry analysis is one of the powerful tools to analyse nonlinear ordinary differential equations. We review the effectiveness of this method in terms of various symmetries. We present the method of deriving Lie point symmetries, contact symmetries, hidden symmetries, nonlocal symmetries, ...

  10. Coding Chinese Characters on an Ordinary Typewriter.

    Science.gov (United States)

    Gledhill, Donald F.; Wu, C. K.

    Presented in this paper is an illustration of the Lantran Chincode System for coding the Chinese language on ordinary English language typewriters or computer terminal keyboards. The key element of the Lantran coding is the use of the Pinyin phonetic romanization which has been officially standard in Communist China for the past 10 years. The end…

  11. Children's Understanding of Ordinary and Extraordinary Minds

    Science.gov (United States)

    Lane, Jonathan D.; Wellman, Henry M.; Evans, E. Margaret

    2010-01-01

    How and when do children develop an understanding of extraordinary mental capacities? The current study tested 56 preschoolers on false-belief and knowledge-ignorance tasks about the mental states of contrasting agents--some agents were ordinary humans, some had exceptional perceptual capacities, and others possessed extraordinary mental…

  12. The Ordinariness of Youth Linguascapes in Mongolia

    Science.gov (United States)

    Dovchin, Sender

    2017-01-01

    Drawing on varied offline and online contexts, this article indicates that youth linguistic diversity in contemporary Mongolia is better understood from the perspective of "the ordinariness of linguascapes." The notion of "linguascapes" is important in capturing the rising complexity of youth mixed language practices…

  13. Exponential function method for solving nonlinear ordinary ...

    Indian Academy of Sciences (India)

    Abstract. A new approach, named the exponential function method (EFM) is used to obtain solutions to nonlinear ordinary differential equations with constant coefficients in a semi-infinite domain. The form of the solutions of these problems is considered to be an expansion of exponential functions with unknown coefficients.

  14. Ordinary violence and social change in Africa

    NARCIS (Netherlands)

    Bouje, J.; Bruijn, de M.E.

    2014-01-01

    Ordinary social violence, - i.e. recurrent mental or physical aggression occurring between closely related people - structures social relationships in Africa, and in the world. Studies of violence in Africa often refer to ethnic wars and explicit conflicts and do not enter the hidden domain of

  15. Internal Structure and Mineralogy of Differentiated Asteroids Assuming Chondritic Bulk Composition: The Case of Vesta

    Science.gov (United States)

    Toplis, M. J.; Mizzon, H.; Forni, O.; Monnereau, M.; Prettyman, T. H.; McSween, H. Y.; McCoy, T. J.; Mittlefehldt, D. W.; DeSanctis, M. C.; Raymond, C. A.; hide

    2012-01-01

    dominated by olivine (>85%) for carbonaceous chondrites, but to be a roughly equal mixture of olivine and pyroxene for ordinary chondrite precursors. All bulk compositions have a significant core, but the relative proportions of metal and sulphide can be widely different. Using these data, total core size (metal+ sulphide) and average core densities can be calculated, providing a useful reference frame within which to consider geophysical/gravity data of the Dawn mission.

  16. Distribution of 26Al in the CR chondrite chondrule-forming region of the protoplanetary disk

    Science.gov (United States)

    Schrader, Devin L.; Nagashima, Kazuhide; Krot, Alexander N.; Ogliore, Ryan C.; Yin, Qing-Zhu; Amelin, Yuri; Stirling, Claudine H.; Kaltenbach, Angela

    2017-03-01

    We report on the mineralogy, petrography, and in situ measured oxygen- and magnesium-isotope compositions of eight porphyritic chondrules (seven FeO-poor and one FeO-rich) from the Renazzo-like carbonaceous (CR) chondrites Graves Nunataks 95229, Grosvenor Mountains 03116, Pecora Escarpment 91082, and Queen Alexandra Range 99177, which experienced minor aqueous alteration and very mild thermal metamorphism. We find no evidence that these processes modified the oxygen- or Al-Mg isotope systematics of chondrules in these meteorites. Olivine, low-Ca pyroxene, and plagioclase within an individual chondrule have similar O-isotope compositions, suggesting crystallization from isotopically uniform melts. The only exceptions are relict grains in two of the chondrules; these grains are 16O-enriched relative to phenocrysts of the host chondrules. Only the FeO-rich chondrule shows a resolvable excesses of 26Mg, corresponding to an inferred initial 26Al/27Al ratio [(26Al/27Al)0] of (2.5 ± 1.6) × 10-6 (±2SE). Combining these results with the previously reported Al-Mg isotope systematics of CR chondrules (Nagashima et al., 2014, Geochem. J. 48, 561), 7 of 22 chondrules (32%) measured show resolvable excesses of 26Mg; the presence of excess 26Mg does not correlate with the FeO content of chondrule silicates. In contrast, virtually all chondrules in weakly metamorphosed (petrologic type 3.0-3.1) unequilibrated ordinary chondrites (UOCs), Ornans-like carbonaceous (CO) chondrites, and the ungrouped carbonaceous chondrite Acfer 094 show resolvable excesses of 26Mg. The inferred (26Al/27Al)0 in CR chondrules with resolvable excesses of 26Mg range from (1.0 ± 0.4) × 10-6 to (6.3 ± 0.9) × 10-6, which is typically lower than (26Al/27Al)0 in the majority of chondrules from UOCs, COs, and Acfer 094. Based on the inferred (26Al/27Al)0, three populations of CR chondrules are recognized; the population characterized by low (26Al/27Al)0 (4.0-0.3+0.5 Ma after the formation of CAIs with

  17. Opaque Assemblages in CK and CV Carbonaceous Chondrites

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2014-08-01

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

  19. Labile trace elements in carbonaceous chondrites - A survey

    Science.gov (United States)

    Xiao, Xiaoyue; Lipschutz, Michael E.

    1992-01-01

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

  20. Reclassification of Villalbeto de la Peña—Occurrence of a winonaite-related fragment in a hydrothermally metamorphosed polymict L-chondritic breccia

    Science.gov (United States)

    Bischoff, Addi; Dyl, Kathryn A.; Horstmann, Marian; Ziegler, Karen; Wimmer, Karl; Young, Edward D.

    2013-04-01

    The Villalbeto de la Peña meteorite that fell in 2004 in Spain was originally classified as a moderately shocked L6 ordinary chondrite. The recognition of fragments within the Villalbeto de la Peña meteorite clearly bears consequences for the previous classification of the rock. The oxygen isotope data clearly show that an exotic eye-catching, black, and plagioclase-(maskelynite)-rich clast is not of L chondrite heritage. Villalbeto de la Peña is, consequently, reclassified as a polymict chondritic breccia. The oxygen isotope data of the clast are more closely related to data for the winonaite Tierra Blanca and the anomalous silicate-bearing iron meteorite LEW 86211 than to the ordinary chondrite groups. The REE-pattern of the bulk inclusion indicates genetic similarities to those of differentiated rocks and their minerals (e.g., lunar anorthosites, eucritic, and winonaitic plagioclases) and points to an igneous origin. The An-content of the plagioclase within the inclusion is increasing from the fragment/host meteorite boundary (approximately An10) toward the interior of the clast (approximately An52). This is accompanied by a successive compositionally controlled transformation of plagioclase into maskelynite by shock. As found for plagioclase, compositions of individual spinels enclosed in plagioclase (maskelynite) also vary from the border toward the interior of the inclusion. In addition, huge variations in oxygen isotope composition were found correlating with distance into the object. The chemical and isotopical profiles observed in the fragment indicate postaccretionary metamorphism under the presence of a volatile phase.

  1. Processes of aesthetic transformation in ordinary landscapes

    DEFF Research Database (Denmark)

    Krarup, Jonna Majgaard

    2004-01-01

    it was distributed systematically as an almost industrially produced landscape element. Windbreaks are now regarded as a traditional element in the Danish agricultural landscape. As a landscape element it is an international phenomenon known and used in Germany, France, England etc. Originally local farming...... practices, natural conditions, techniques and national legislation in the respective countries, formed the aesthetic expression. In this respect one could speak of the impact of northern nature on the aesthetic expression of the Danish windbreaks, as well as the impact from national phenomena....... These features determined the specific aesthetic and architectural identity of ordinary Danish, i.e. Nordic, landscapes. Contemporary cultural changes such as the aesthetification of everyday life and of ordinary landscape, i.e. farming landscape, are now manifest in the way the windbreaks are motivated...

  2. Magnetar-powered ordinary Type IIP supernovae

    Science.gov (United States)

    Sukhbold, Tuguldur; Thompson, Todd A.

    2017-11-01

    We investigate the properties of Type IIP supernovae that are dominantly powered by the rotational kinetic energy of the newly born neutron star. While the spin-down of a magnetar has previously been proposed as a viable energy source in the context of superluminous supernovae, we show that a similar mechanism could produce both normal and peculiar Type IIP supernova light curves from red supergiant progenitors for a range of initial spin periods and equivalent dipole magnetic field strengths. Although the formation channel for such magnetars in a typical red supergiant progenitor is unknown, it is tantalizing that this proof of concept model is capable of producing ordinary Type IIP light-curve properties, perhaps implying that rotation rate and magnetic field strength may play important roles in some ordinary looking Type IIP supernova explosions.

  3. The Trace-Element Composition of a Silica-rich Clast in the Bovedy (L3/4) Chondrite

    Science.gov (United States)

    Ruzicka, A.; Kring, D. A.; Hill, D. H.; Boynton, W. V.

    1993-07-01

    The discovery of a ~4 X 4.5 X 7 mm^3, igneous-textured, silica-rich clast in the Bovedy chondrite [1] may have important implications regarding igneous processes that occurred on chondritic parent bodies [1,2]. This clast, designated Bo-1, is comprised of orthopyroxene, a silica polymorph, two feldspars, pigeonite, and minor chromite and trace metal and sulfide [1]. Bulk SEM/EMPA analyses of the clast indicated superchondritic Si/Mg and Si/Fe ratios, which Ruzicka and Boynton [1] proposed was produced by extensive olivine fractionation from a melted L-chondrite precursor. The low Fe/Mn ratio and low metal and sulfide abundances also suggest that the clast is largely missing a chondritic complement of metal and sulfide. To test these hypotheses, we measured the bulk composition of the clast using INAA techniques and found that the siderophile elements were lost in a two-step process and that partial melting also depleted incompatible lithophile elements. Lithophile Elements: Two splits (2.94 and 2.39 mg) of Bo-1 were analyzed. The concentrations of major elements (Ca, Fe, Cr, K, Na) bracket those previously determined by SEM/EMPA [1], suggesting that the two splits are reasonably representative of the bulk clast. If olivine and metal had been removed from an ordinary chondrite melt to produce the clast, then incompatible lithophile trace elements should have been enriched. Contrary to this expectation, however, the REE, Zr, Hf, Th, Sr, Rb, Cs and Br are consistently depleted to a level of 0.5-1.0 X CI abundances, while all of them (except the highly volatile Cs and Br) have concentrations of ~1.0-2.0 X CI abundances in ordinary chondrites. If the clast had been derived from melted ordinary chondrite material, then an additional step that removed incompatible elements, such as the loss of a partial melt, must have occurred. Siderophile Elements: Unlike lithophile trace elements, which are relatively unfractionated, the siderophiles Ni, Co, and Au are dramatically

  4. Solutions manual to accompany Ordinary differential equations

    CERN Document Server

    Greenberg, Michael D

    2014-01-01

    Features a balance between theory, proofs, and examples and provides applications across diverse fields of study Ordinary Differential Equations presents a thorough discussion of first-order differential equations and progresses to equations of higher order. The book transitions smoothly from first-order to higher-order equations, allowing readers to develop a complete understanding of the related theory. Featuring diverse and interesting applications from engineering, bioengineering, ecology, and biology, the book anticipates potential difficulties in understanding the various solution steps

  5. Carbonaceous chondrites and the origin of life

    Science.gov (United States)

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

    1993-01-01

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

  6. Pyrolysis-GC×GC-TOFMS to characterize carbonaceous chondrites

    OpenAIRE

    Watson, J. S.; Pearson, V. K.; Gilmour, I.; Pillinger, C. T.; Turner, D.; Perkins, R.; Morgan, G. H.

    2005-01-01

    Using pyrolysis-GCxGC-TOFMS to analyze organic carbon in carbonaceous chondrites gives a massive increase in both sensitivity and structural information from samples when compared to traditional Py-GC-MS.

  7. Origin and Development of Phosphate Minerals in Metamorphosed LL Chondrites

    Science.gov (United States)

    Dreeland, L.; Jones, R. H.

    2011-03-01

    We describe the occurrence of chlorapatite and merrillite in metamorphosed LL chondrites, including grain size distributions, mineral associations, and compositions. Development of phosphate minerals appears to postdate the peak of metamorphism.

  8. Metastable carbon in two chondritic porous interplanetary dust particles

    Science.gov (United States)

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

    1987-03-01

    The authors have suggested previously that a record of graphitization is preserved in chondritic porous (CP) aggregates and carbonaceous chondrites. Here they report further analytical electron microscope (AEM) studies on carbonaceous material in two CP aggregates which suggest that a record of hydrocarbon carbonization may also be preserved in these materials. This suggestion is based upon the presence of well-ordered carbon-2H (lonsdaleite)in CP aggregates W7029*A and W7010*A2.

  9. Numerical analysis of systems of ordinary and stochastic differential equations

    CERN Document Server

    Artemiev, S S

    1997-01-01

    This text deals with numerical analysis of systems of both ordinary and stochastic differential equations. It covers numerical solution problems of the Cauchy problem for stiff ordinary differential equations (ODE) systems by Rosenbrock-type methods (RTMs).

  10. Correlated Petrologic and Geochemical Characteristics of CO3 Chondrites

    Science.gov (United States)

    Rubin, Alan E.

    1998-01-01

    Many properties of CO3 chondrites have been shown previously to have resulted from thermal metamorphism; petrologic subtypes 3.0-3.7 have been assigned to members of the group. Additional properties that correlate with the metamorphic sequence but seem to have resulted from hydrothermal alteration include the modal abundance of amoeboid olivine inclusions (AOI), chondrule size, the types of refractory inclusions and whole rock O isotopic composition. The percentage of rimmed AOI increases with petrologic subtype. The rims most likely formed during hydrothermal alteration. The previously reported correlation between AOI abundance and chondrite subtype is probably an artifact due to the difficulty in recognizing small unrimmed AOI in the least metamorphosed CO3 chondrites. Because large (>=200 micron size) porphyritic chondrules have nearly the same mean size in all CO3 chondrites, it seems likely that the correlation between chondrule size and subtype is due to alteration of the smallest chondrules to the point of unrecognizability as complete objects in the more metamorphosed CO3 chondrites. The previously reported decrease in the proportion of melilite-rich refractory inclusions with increasing petrologic subtype may have resulted from more extensive hydrothermal alteration in CO3 .4-3.7 chondrites that converted primary melilite into Ca-pyroxene, andradite and nepheline. Alteration probably caused the preferential occurrence of O-16-poor oxygen isotopes in the more metamorphosed whole rock samples.

  11. 7 CFR 28.407 - Good Ordinary Color.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Good Ordinary Color. 28.407 Section 28.407 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Color Grade of American Upland Cotton § 28.407 Good Ordinary Color. Good Ordinary Color is color which is within the range...

  12. 7 CFR 28.406 - Strict Good Ordinary Color.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Strict Good Ordinary Color. 28.406 Section 28.406... for the Color Grade of American Upland Cotton § 28.406 Strict Good Ordinary Color. Strict Good Ordinary Color is color which is within the range represented by a set of samples in the custody of the...

  13. Odeint - Solving Ordinary Differential Equations in C++

    Science.gov (United States)

    Ahnert, Karsten; Mulansky, Mario

    2011-09-01

    Many physical, biological or chemical systems are modeled by ordinary differential equations (ODEs) and finding their solution is an every-day-task for many scientists. Here, we introduce a new C++ library dedicated to find numerical solutions of initial value problems of ODEs: odeint (www.odeint.com). odeint is implemented in a highly generic way and provides extensive interoperability at top performance. For example, due to it's modular design it can be easily parallized with OpenMP and even runs on CUDA GPUs. Despite that, it provides a convenient interface that allows for a simple and easy usage.

  14. Spade: An H Chondrite Impact-melt Breccia that Experienced Post-shock Annealing

    Science.gov (United States)

    Rubin, Alan E.; Jones, Rhian H.

    2006-01-01

    The low modal abundances of relict chondrules (1.8 Vol%) and of coarse (i.e. >= 2200 micron-size) isolated mafic silicate grains (1.8 Vol%) in Spade relative to mean H6 chondrites (11.4 and 9.8 vol%, respectively) show Spade to be a rock that has experienced a significant degree of melting. Various petrographic features (e.g., chromite-plagioclase assemblages, chromite veinlets, silicate darkening) indicate that melting was caused by shock. Plagioclase was melted during the shock event and flowed so that it partially to completely surrounded nearby mafic silicate grains. During crystallization, plagioclase developed igneous zoning. Low-Ca pyroxene that crystallized from the melt (or equilibrated with the melt at high temperatures) acquired relatively high amounts of CaO. Metallic Fe-Ni cooled rapidly below the Fe-Ni solws and transformed into martensite. Subsequent reheating of the rock caused transformation of martensite into abundant duplex plessite. Ambiguities exist in the shock stage assignment of Spade. The extensive silicate darkening, the occurrence of chromite-plagioclase assemblages, and the impact-melted characteristics of Spade are consistent with shock stage S6. Low shock (stage S2) is indicated by the undulose extinction and lack of planar fractures in olivine. This suggests that Spade reached a maximum prior shock level equivalent to stage S6 and then experienced post-shock annealing (probably to stage Sl). These events were followed by a less intense impact that produced the undulose extinction in the olivine, characteristic of shock stage S2. Annealing could have occurred if Spade were emplaced near impact melts beneath the crater floor or deposited in close proximity to hot debris within an ejecta blanket. Spade firmly establishes the case for post-shock annealing. This may have been a common process on ordinary chondrites (OC) asteroids.

  15. A textbook on ordinary differential equations

    CERN Document Server

    Ahmad, Shair

    2015-01-01

    This book offers readers a primer on the theory and applications of Ordinary Differential Equations. The style used is simple, yet thorough and rigorous. Each chapter ends with a broad set of exercises that range from the routine to the more challenging and thought-provoking. Solutions to selected exercises can be found at the end of the book. The book contains many interesting examples on topics such as electric circuits, the pendulum equation, the logistic equation, the Lotka-Volterra system, the Laplace Transform, etc., which introduce students to a number of interesting aspects of the theory and applications. The work is mainly intended for students of Mathematics, Physics, Engineering, Computer Science and other areas of the natural and social sciences that use ordinary differential equations, and who have a firm grasp of Calculus and a minimal understanding of the basic concepts used in Linear Algebra. It also studies a few more advanced topics, such as Stability Theory and Boundary Value Problems, whic...

  16. Northwest Africa 428: Impact-induced Annealing of an L6 Chondrite Breccia

    Science.gov (United States)

    Rubin, Alan E.

    2006-01-01

    of NWA 428 (L6) and MIL 99301 (LL6) indicate that impact heating affected more than 1 ordinary chondrite parent body.

  17. A Distinctive Silica-Rich, Sodium-Poor Igneous Clast in the Bovedy (L3) Chondrite

    Science.gov (United States)

    Ruzicka, A.; Boynton, W. V.

    1992-07-01

    Description of Bo-1. One slab of the Bovedy (L3) chondrite contains a large (~ 4 x 7 mm) white object that in hand specimen resembles the generally chondritic lithic fragment studied by Rubin et al. (1981). However, SEM, and EMPA studies of this object, designated Bo-1, reveal an unusually Si-rich, Na-poor bulk composition that is manifested by the presence of a silica mineral, the complete absence of olivine, and feldspar that is less sodic than usual for ordinary chondrites. The clast is a highly crystalline igneous rock and exhibits a well-defined crystallization sequence. Orthopyroxene (opx) comprises 83.8 vol% of Bo-1 and is zoned from En(sub)92-85 Wo(sub)0.1-0.2 to En(sub)74 Wo(sub)1.9-2.9. The more magnesian, less calcic opx was the first phase to crystallize in Bo-1. A silica mineral (SiO2, 6.2 vol%), probably either tridymite or cristobalite, crystallized next and appears slightly "corroded" (and veined) by clinopyroxene, suggesting minor reaction between the silica mineral and its surroundings. A small amount (1 vol%) of euhedral-subhedral pigeonite (pig) also crystallized about this time. Plagioclase (plag) was the last phase to join the crystallization sequence and consists of a fine-scale, often lamellar, intergrowth of bytownite-labradorite (5.8 vol%, mainly An(sub)70- 75Or(sub)1-03) and oligoclase (3.1 vol%, mainly An(sub)15-24 Or(sub)13-6). The latter deviates from feldspar stoichiometry and may be partly amorphous. Volumetrically insignificant augite (aug) occurs as (exsolution?) patches within opx, as thin veinlets crossing SiO(sub)2 grains, and as thin rims at the interface of SiO(sub)2 and plag. The rimming and veining aug may have crystallized together with plag from the last liquid in the rock. Minor chromite (0.2 vol%) and trace metal and sulfide are also present. Bulk composition of Bo-1. The composition of the clast was determined by combining SEM modal data with EMPA data for each phase. The calculated composition (in wt%) is: SiO2, 57

  18. Paleomagnetic evidence for a partially differentiated H chondrite parent planetesimal

    Science.gov (United States)

    Bryson, J. F. J.; Weiss, B. P.; Scholl, A.; Getzin, B. L.; Abrahams, J. N. H.; Nimmo, F.

    2016-12-01

    The texture, composition and ages of chondrites have all been used to argue that the parent bodies of these meteorites did not undergo planetary differentiation. Without a core, these planetesimals could not have generated planetary magnetic fields, hence chondrites are predicted to be unmagnetized. Here, we test this hypothesis by applying synchrotron x-ray microscopy to the metallic melt veins in the metamorphosed H chondrite breccia Portales Valley. We find that tetrataenite nanostructures in these veins are uniformly magnetized, suggesting that the H chondrite parent body generated a stable, 10 µT ancient field. We also performed alternating field (AF) demagnetization on bulk silicate-rich portions of Portales Valley, finding that both the large grain size of the metal in these subsamples and the presence of tetrataenite hinder the reliable interpretation of these measurements. Based on 40Ar/39Ar dating and the metallographic cooling rate, we propose that this field inferred from x-ray microscopy was generated 100 Myr after solar system formation and lasted >5 Myr. These properties are consistent with a dynamo field generated by core solidification, implying that the H chondrite parent body was partially differentiated. This conclusion is supported by our analyses of the H4 chondrite Forest Vale, which show that H chondrite magnetization is unlikely to be a relic signature of early nebular or solar wind fields (Getzin et al., this meeting; Oran et al., this meeting). We propose that partial differentiation could result form prolonged accretion over millions of years, possibly in two stages. In this scenario, the earliest accreted material melted from the radioactive decay of abundant 26Al, forming a core and rocky achondritic mantle, while the later accreted material was less metamorphosed, forming an undifferentiated crust. We demonstrate that, with the inclusion of an insulating regolith, the thermal evolution of such a body is consistent with the measured

  19. The mineralogy of the Yaringie Hill meteorite —A new H5 chondrite from South Australia

    Science.gov (United States)

    Tappert, R.; Foden, J.; Pring, A.

    2009-12-01

    The Yaringie Hill meteorite is a new H5 ordinary chondrite found in the Gawler Ranges, South Australia. The meteorite, which shows only minor signs of terrestrial weathering, is predominantly composed of olivine (Fa17.2), orthopyroxene (Fs15.1Wo1.1), and three distinct phases of nickeliferous iron metal (kamacite, taenite, tetrataenite). Other minerals include troilite, plagioclase (Ab81An16Or3), clinopyroxene (En52Wo42Fs6), chlorapatite, merrillite, ilmenite, and native copper. Three types of spinel with distinctive textures (coarse, skeletal aggregates, rounded aggregates) and with compositions close to the join MgAl2O4-FeCr2O4 are also present. Chondrules within the Yaringie Hill meteorite, which often have poorly defined boundaries, are placed in a recrystallized matrix. Shock indicators suggest that the meteorite experienced only weak shock metamorphism (S3).

  20. Organic Analysis of Catalytic Fischer-Tropsch Type Synthesis Products: Are they Similar to Organics in Chondritic Meteorites?

    Science.gov (United States)

    Yazzie, Cyriah A.; Locke, Darren R.; Johnson, Natasha M.

    2014-01-01

    Fischer-Tropsch Type (FTT) synthesis of organic compounds has been hypothesized to occur in the early solar nebula that formed our Solar System. FTT is a collection of abiotic chemical reactions that convert a mixture of carbon monoxide and hydrogen over nano-catalysts into hydrocarbons and other more complex aromatic compounds. We hypothesized that FTT can generate similar organic compounds as those seen in chondritic meteorites; fragments of asteroids that are characteristic of the early solar system. Specific goals for this project included: 1) determining the effects of different FTT catalyst, reaction temperature, and cycles on organic compounds produced, 2) imaging of organic coatings found on the catalyst, and 3) comparison of organic compounds produced experimentally by FTT synthesis and those found in the ordinary chondrite LL5 Chelyabinsk meteorite. We used Pyrolysis Gas Chromatography Mass Spectrometry (PY-GCMS) to release organic compounds present in experimental FTT and meteorite samples, and Scanning Electron Microscopy (SEM) to take images of organic films on catalyst grains.

  1. COMPOSITION OF POTENTIALLY HAZARDOUS ASTEROID (214869) 2007 PA8: AN H CHONDRITE FROM THE OUTER ASTEROID BELT

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, Juan A.; Reddy, Vishnu; Corre, Lucille Le [Planetary Science Institute, Tucson, AZ 85719 (United States); Dykhuis, Melissa [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85719 (United States); Lindsay, Sean, E-mail: jsanchez@psi.edu [Atmospheric, Oceanic, and Planetary Physics, University of Oxford (United Kingdom)

    2015-07-20

    Potentially hazardous asteroids (PHAs) represent a unique opportunity for physical characterization during their close approaches to Earth. The proximity of these asteroids makes them accessible for sample-return and manned missions, but could also represent a risk for life on Earth in the event of collision. Therefore, a detailed mineralogical analysis is a key component in planning future exploration missions and developing appropriate mitigation strategies. In this study we present near-infrared spectra (∼0.7–2.55 μm) of PHA (214869) 2007 PA8 obtained with the NASA Infrared Telescope Facility during its close approach to Earth on 2012 November. The mineralogical analysis of this asteroid revealed a surface composition consistent with H ordinary chondrites. In particular, we found that the olivine and pyroxene chemistries of 2007 PA8 are Fa{sub 18}(Fo{sub 82}) and Fs{sub 16}, respectively. The olivine–pyroxene abundance ratio was estimated to be 47%. This low olivine abundance and the measured band parameters, close to the H4 and H5 chondrites, suggest that the parent body of 2007 PA8 experienced thermal metamorphism before being catastrophically disrupted. Based on the compositional affinity, proximity to the J5:2 resonance, and estimated flux of resonant objects we determined that the Koronis family is the most likely source region for 2007 PA8.

  2. Early Solar System Alkali Fractionation Events Recorded by K-Ca Isotopes in the Yamato-74442 LL-Chondritic Breccia

    Science.gov (United States)

    Tatsunori, T.; Misawa, K.; Okano, O.; Shih, C.-Y.; Nyquist, L. E.; Simon, J. I.; Tappa, M. J.; Yoneda, S.

    2015-01-01

    Radiogenic ingrowth of Ca-40 due to decay of K-40 occurred early in the solar system history causing the Ca-40 abundance to vary within different early-former reservoirs. Marshall and DePaolo ] demonstrated that the K-40/Ca-40 decay system could be a useful radiogenic tracer for studies of terrestrial rocks. Shih et al. [3,4] determined 40K/40Ca ages of lunar granitic rock fragments and discussed the chemical characteristics of their source materials. Recently, Yokoyama et al. [5] showed the application of the K-40/Ca-40 chronometer for high K/Ca materials in ordinary chondrites (OCs). High-precision calcium isotopic data are needed to constrain mixing processes among early solar system materials and the time of planetesimal formation. To better constrain the solar system calcium isotopic compositions among astromaterials, we have determined the calcium isotopic compositions of OCs and an angrite. We further estimated a source K/Ca ratio for alkali-rich fragments in a chondritic breccia using the estimated solar system initial Ca-40/Ca-44.

  3. Oxygen isotopic ratios of primordial water in carbonaceous chondrites

    Science.gov (United States)

    Fujiya, Wataru

    2018-01-01

    In this work, I estimate the δ18 O and δ17 O values of primordial water in CM chondrites to be 55 ± 13 and 35 ± 9‰, respectively, based on whole-rock O and H data. Also, I found that the O and/or H data of Antarctic meteorites are biased, which is attributed to terrestrial weathering. This characteristic O isotopic ratio of water together with corresponding water abundances in CM chondrites are consistent with the origin of water as ice processed by photochemical reactions at the outer regions of the solar nebula, where mass-independent O isotopic fractionation and water destruction may have occurred. Another possible mechanism to produce the inferred O isotopic ratio of water would be O isotopic fractionation between water vapor and ice, which likely occurred near the condensation front of H2O (snow line) in the solar nebula. The inferred O isotopic ratio of water suggests that carbonate in CM chondrites formed at low temperatures of <150 °C. The O isotopic ratios of primordial water in chondrites other than CM chondrites are not well constrained.

  4. Chemical fractionations in meteorites. XI - C2 chondrites

    Science.gov (United States)

    Wolf, R.; Richter, G. R.; Woodrow, A. B.; Anders, E.

    1980-01-01

    Measurements of the compositions of 20 trace elements in the representative C2 chondrites Boriskino, Cold Bokkeveld, Erakot, Essebi, Haripura, Santa Cruz and Al Rais are reported. The contents of Ag, Au, Bi, Cd, Cs, Ge, In, Ir, Ni, Os, Pd, Rb, Re, Sb, Se, Sn, Te, Tl, U, and Zn were determined by radiochemical neutron activation analysis. The siderophile abundances of the C2 chondrites are found to be less uniform than those of other carbonaceous chondrites, while the C2R chondrite Al Rais is systematically lower in 12 volatiles than the C2M chondrites. Enrichment of Bi and Tl found in Erakot and Haripura indicate the possible presence of the late condensate mysterite. Volatile abundances are shown to agree with matrix contents for meteorites that have suffered little aqueous alteration, however to be 20-30% lower for the more altered meteorites. Finally, the decline of element abundance with volatility is shown to be consistent with the sigmoid curve explained by the two-component model.

  5. Almahata Sitta Sample MS-181: The First Carbonaceous Chondrite (CBa) from Asteroid 2008 TC3

    Science.gov (United States)

    Bischoff, A.; Horstmann, H.; Heusser, G.; Pack, A.; Albrecht, N.

    2012-09-01

    Among the numerous meteorite fragments collected in the Almahata Sitta strewn field a huge diversity of different types of meteorites including various ureilites and chondrites were recovered. MS-181 is the first carbonaceous chondrite sample (CB).

  6. Ordinary differential equations basics and beyond

    CERN Document Server

    Schaeffer, David G

    2016-01-01

    This book develops the theory of ordinary differential equations (ODEs), starting from an introductory level (with no prior experience in ODEs assumed) through to a graduate-level treatment of the qualitative theory, including bifurcation theory (but not chaos). While proofs are rigorous, the exposition is reader-friendly, aiming for the informality of face-to-face interactions. A unique feature of this book is the integration of rigorous theory with numerous applications of scientific interest. Besides providing motivation, this synthesis clarifies the theory and enhances scientific literacy. Other features include: (i) a wealth of exercises at various levels, along with commentary that explains why they matter; (ii) figures with consistent color conventions to identify nullclines, periodic orbits, stable and unstable manifolds; and (iii) a dedicated website with software templates, problem solutions, and other resources supporting the text. Given its many applications, the book may be used comfortably in sc...

  7. From ordinary to partial differential equations

    CERN Document Server

    Esposito, Giampiero

    2017-01-01

    This book is addressed to mathematics and physics students who want to develop an interdisciplinary view of mathematics, from the age of Riemann, Poincaré and Darboux to basic tools of modern mathematics. It enables them to acquire the sensibility necessary for the formulation and solution of difficult problems, with an emphasis on concepts, rigour and creativity. It consists of eight self-contained parts: ordinary differential equations; linear elliptic equations; calculus of variations; linear and non-linear hyperbolic equations; parabolic equations; Fuchsian functions and non-linear equations; the functional equations of number theory; pseudo-differential operators and pseudo-differential equations. The author leads readers through the original papers and introduces new concepts, with a selection of topics and examples that are of high pedagogical value.

  8. A short course in ordinary differential equations

    CERN Document Server

    Kong, Qingkai

    2014-01-01

    This text is a rigorous treatment of the basic qualitative theory of ordinary differential equations, at the beginning graduate level. Designed as a flexible one-semester course but offering enough material for two semesters, A Short Course covers core topics such as initial value problems, linear differential equations, Lyapunov stability, dynamical systems and the Poincaré—Bendixson theorem, and bifurcation theory, and second-order topics including oscillation theory, boundary value problems, and Sturm—Liouville problems. The presentation is clear and easy-to-understand, with figures and copious examples illustrating the meaning of and motivation behind definitions, hypotheses, and general theorems. A thoughtfully conceived selection of exercises together with answers and hints reinforce the reader's understanding of the material. Prerequisites are limited to advanced calculus and the elementary theory of differential equations and linear algebra, making the text suitable for senior undergraduates as w...

  9. Ordinary differential equations a graduate text

    CERN Document Server

    Bhamra, K S

    2015-01-01

    ORDINARY DIFFERENTIAL EQUATIONS: A Graduate Text presents a systematic and comprehensive introduction to ODEs for graduate and postgraduate students. The systematic organized text on differential inequalities, Gronwall's inequality, Nagumo's theorems, Osgood's criteria and applications of different equations of first order is dealt with in a greater depth. The book discusses qualitative and quantitative aspects of the Strum - Liouville problems, Green's function, integral equations, Laplace transform and is supported by a number of worked-out examples in each lesson to make the concepts clear. A lot of stress on stability theory is laid down, especially on Lyapunov and Poincare stability theory. A numerous figures in various lessons (in particular lessons dealing with stability theory) have been added to clarify the key concepts in DE theory. Nonlinear oscillation in conservative systems and Hamiltonian systems highlights basic nature of the systems considered. Perturbation techniques lesson deals in fairly d...

  10. Ordinary differential equations principles and applications

    CERN Document Server

    Nandakumaran, A K; George, Raju K

    2017-01-01

    Written in a clear, logical and concise manner, this comprehensive resource allows students to quickly understand the key principles, techniques and applications of ordinary differential equations. Important topics including first and second order linear equations, initial value problems and qualitative theory are presented in separate chapters. The concepts of two point boundary value problems, physical models and first order partial differential equations are discussed in detail. The text uses tools of calculus and real analysis to get solutions in explicit form. While discussing first order linear systems, linear algebra techniques are used. The real-life applications are interspersed throughout the book to invoke reader's interest. The methods and tricks to solve numerous mathematical problems with sufficient derivations and explanation are provided. The proofs of theorems are explained for the benefit of the readers.

  11. Ordinary differential equations and mechanical systems

    CERN Document Server

    Awrejcewicz, Jan

    2014-01-01

    This book applies a step-by-step treatment of the current state-of-the-art of ordinary differential equations used in modeling of engineering systems/processes and beyond. It covers systematically ordered problems, beginning with first and second order ODEs, linear and higher-order ODEs of polynomial form, theory and criteria of similarity, modeling approaches, phase plane and phase space concepts, stability optimization, and ending on chaos and synchronization. Presenting both an overview of the theory of the introductory differential equations in the context of applicability and a systematic treatment of modeling of numerous engineering and physical problems through linear and non-linear ODEs, the volume is self-contained, yet serves both scientific and engineering interests. The presentation relies on a general treatment, analytical and numerical methods, concrete examples, and engineering intuition. The scientific background used is well balanced between elementary and advanced level, making it as a uniqu...

  12. Spectral theory of ordinary differential operators

    CERN Document Server

    Weidmann, Joachim

    1987-01-01

    These notes will be useful and of interest to mathematicians and physicists active in research as well as for students with some knowledge of the abstract theory of operators in Hilbert spaces. They give a complete spectral theory for ordinary differential expressions of arbitrary order n operating on -valued functions existence and construction of self-adjoint realizations via boundary conditions, determination and study of general properties of the resolvent, spectral representation and spectral resolution. Special attention is paid to the question of separated boundary conditions, spectral multiplicity and absolutely continuous spectrum. For the case nm=2 (Sturm-Liouville operators and Dirac systems) the classical theory of Weyl-Titchmarch is included. Oscillation theory for Sturm-Liouville operators and Dirac systems is developed and applied to the study of the essential and absolutely continuous spectrum. The results are illustrated by the explicit solution of a number of particular problems including th...

  13. A textbook on ordinary differential equations

    CERN Document Server

    Ahmad, Shair

    2014-01-01

    The book is a primer of the theory of Ordinary Differential Equations. Each chapter is completed by a broad set of exercises; the reader will also find a set of solutions of selected exercises. The book contains many interesting examples as well (like the equations for the electric circuits, the pendium equation, the logistic equation, the Lotka-Volterra system, and many other) which introduce the reader to some interesting aspects of the theory and its applications. The work is mainly addressed to students of Mathematics, Physics, Engineering, Statistics, Computer Sciences, with  knowledge of Calculus and Linear Algebra, and contains more advanced topics for further developments, such as Laplace transform; Stability theory and existence of solutions to Boundary Value problems. The authors are preparing a complete solutions manual, containing solutions to all the exercises published in the book. The manual will be available Summer 2014. Instructors who wish to adopt the book may request the manual by writing...

  14. Terrestrial microbes in martian and chondritic meteorites

    Science.gov (United States)

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

    2007-08-01

    Introduction: The best extraterrestrial analogs for microbiology are meteorites. The chemistry and mineralogy of Asteroid Belt and martian (SNC) meteorites are used as tracers of processes that took place in the early solar system. Meteoritic falls, in particular those of carbonaceous chondrites, are regarded as pristine samples of planetesimal evolution as these rocks are primitive and mostly unprocessed since the formation of the solar system 4.56 billion years ago. Yet, questions about terrestrial contamination and its effects on the meteoritic isotopic, chemical and mineral characteristics often arise. Meteorites are hosts to biological activity as soon as they are in contact with the terrestrial biosphere, like all rocks. A wide biodiversity was found in 21 chondrites and 8 martian stones, and was investigated with cell culture, microscopy techniques, PCR, and LAL photoluminetry. Some preliminary results are presented here. The sample suite included carbonaceous chondrites of types CR, CV, CK, CO, CI, and CM, from ANSMET and Falls. Past studies documented the alteration of meteorites by weathering and biological activity [1]-[4]. Unpublished observations during aqueous extraction for oxygen isotopic analysis [5], noted the formation of biofilms in water in a matter of days. In order to address the potential modification of meteoritic isotopic and chemical signatures, the culture of microbial contaminating species was initiated in 2005, and after a prolonged incubation, some of the species obtained from cell culture were analyzed in 2006. The results are preliminary, and a systematic catalog of microbial contaminants is developing very slowly due to lack of funding. Methods: The primary method was cell culture and PCR. Chondrites. Chondritic meteorite fragments were obtained by breaking stones of approximately one gram in sterile mortars. The core of the rocks, presumably less contaminated than the surface, was used for the present microbial study, and the

  15. Albite dissociation reaction in the Northwest Africa 8275 shocked LL chondrite and implications for its impact history

    Science.gov (United States)

    Miyahara, Masaaki; Ohtani, Eiji; Yamaguchi, Akira

    2017-11-01

    An impact event recorded in the Northwest Africa (NWA) 8275 LL7 ordinary chondrite was investigated based on high-pressure mineralogy of pervasive shock-melt veins present in the rock. NWA 8275 consists of olivine, low-Ca pyroxene, plagioclase (albite-oligoclase composition), and minor high-Ca pyroxene, K-feldspar, phosphate minerals, metallic Fe-Ni and iron sulfide. Plagioclase and K-feldspar grains near the shock-melt veins have become amorphous, although no high-pressure polymorphs of olivine and pyroxene were identified in or adjacent the shock-melt veins. Raman spectroscopy and focused ion beam (FIB)-assisted transmission electron microscopy (TEM) observations reveal that plagioclase entrained around the center portion of the shock-melt veins has dissociated into a jadeite + coesite assemblage. Alternately stacked jadeite and coesite crystals occur in the original plagioclase. On approaching the host rock/shock-melt vein, only jadeite is present. Based on the high-pressure polymorph assemblage, the shock pressure and temperature conditions recorded in the shock-melt veins are ∼3-12 GPa and ∼1973-2373 K, respectively. Following a Rankine-Hugoniot relationship, the impact velocity was at least ∼0.45-1.54 km/s. The duration of high-pressure and high-temperature (HPHT) conditions required for the albite dissociation reaction is estimated a maximum of ∼4-5 s using the phase transition rate of albite, implying that a body of up to ∼9-12 km across collided with the parent body of NWA 8275. The coexistence of jadeite and coesite, the latter of which rarely accompanies jadeite in shocked ordinary chondrites, as a dissociation product of albite requires relatively long duration HPHT conditions. Thus, the impact event recorded in NWA 8275 was likely caused by a larger-than-typical projectile.

  16. Pore Water Convection in Carbonaceous Chondrite Planetesimals

    Science.gov (United States)

    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

  17. The Willowbar meteorite. [shock-brecciated L6 chondrite

    Science.gov (United States)

    Lange, D. E.; Moore, C. B.; Rhoton, K.

    1973-01-01

    Results of microscopic and electron microprobe analyses of a meteorite which fell near Willowbar, Okla., in December 1971. Microscopic examination confirmed the differences in structure which could be seen on the cut faces. Three distinct regions could be recognized: unblackened, blackened, and black veins. Microprobe analyses of the silicate grains in the Willowbar meteorite show that it is an L chondrite. The lack of well-defined chondrules and the large size of the maskelynite grains suggests that it is a type 6 chondrite according to the classification of Van Schmus and Wood (1967). It also has large black veins of the same composition as the matrix, and thus it might best be described as a shock-brecciated L6 chondrite.

  18. A new kind of primitive chondrite, Allan Hills 85085

    Science.gov (United States)

    Scott, Edward R. D.

    1988-01-01

    Allan Hills (ALH) 85085, a chemically and mineralogically unique chondrite whose components have suffered little metamorphism or alteration, is discussed. It is found that ALH 85085 has 4 wt pct chondrules (mean diameter 16 microns), 36 wt pct Fe, Ni, 56 wt pct lithic and mineral silicate fragments, and 2 wt pct trolite. It is suggested that, with the exception of matrix lumps, the components of ALH 85085 formed and accreted in the solar nebula. It is shown that ALH 85085 does not belong to any of the nine chondrite groups and is very different from Kakangari. Similarities between ALH 85085 and Bencubbin and Weatherford suggest that the latter two primitive meteorites may be chondrites with high metal abundances and very large, partly fragmented chondrules.

  19. Regge trajectories of ordinary and non-ordinary mesons from their scattering poles

    Energy Technology Data Exchange (ETDEWEB)

    Nebreda, J.; Carrasco, J. A.; Londergan, J. T.; Pelaez, J. R.; Szczepaniak, A. P.

    2016-01-01

    Our results on obtaining the Regge trajectory of a resonance from its pole in a scattering process and from analytic constraints in the complex angular momentum plane are presented. The method, suited for resonances that dominate an elastic scattering amplitude, has been applied to the ρ(770), f2(1270), f'2(1525) and f0(500) resonances. Whereas for the first three we obtain linear Regge trajectories, characteristic of ordinary quark-antiquark states, for the latter we find a non-linear trajectory with a much smaller slope at the resonance mass. We also show that if a linear trajectory with a slope of typical size is imposed for the f0(500), the corresponding amplitude is at odds with the data. This provides a strong indication of the non-ordinary nature of the sigma meson.

  20. Quantitative FT-IR Analysis for Chondritic Meteorites: Search for C_60 in Meteorites

    Directory of Open Access Journals (Sweden)

    Chunglee Kim

    1998-06-01

    Full Text Available Infrared absorption spectra of 9 bulk samples and 3 acid residues of meteorites were obtained in the mid-infrared region (4000 ~ 400 cm^(-1. From the known composition of meteorites studied, the possible absorption modes were investigated. Most bands of bulk samples occur in the region below 1200 cm^(-1 and they are due to metallic oxides and silicates. The spectra of each group can be distinguished by its own characteristic bands. Acid residues show very distinct features from their bulk samples, and absorption bands due to organic compounds are not evident in their spectra. Quantitative analyses for two carbonaceous (Allende CV3 and Murchison CM2 and one ordinary (Carraweena L3.9 chondrites were performed for the presence of fullerene (C_60 in the meteorites. We calculated the concentration of C_60 in the acid residues by curvefitting the spectra with Gaussian functions. The upper limit of C_60 concentration in these meteorites appears to be less than an order of a few hundred ppm.

  1. Numerical solution of ordinary differential equations

    CERN Document Server

    Fox, L

    1987-01-01

    Nearly 20 years ago we produced a treatise (of about the same length as this book) entitled Computing methods for scientists and engineers. It was stated that most computation is performed by workers whose mathematical training stopped somewhere short of the 'professional' level, and that some books are therefore needed which use quite simple mathematics but which nevertheless communicate the essence of the 'numerical sense' which is exhibited by the real computing experts and which is surely needed, at least to some extent, by all who use modern computers and modern numerical software. In that book we treated, at no great length, a variety of computational problems in which the material on ordinary differential equations occupied about 50 pages. At that time it was quite common to find books on numerical analysis, with a little on each topic ofthat field, whereas today we are more likely to see similarly-sized books on each major topic: for example on numerical linear algebra, numerical approximation, numeri...

  2. Ubiquitous high-FeO silicates in enstatite chondrites

    Science.gov (United States)

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

    1987-01-01

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

  3. Symmetries, integrals and solutions of ordinary differential equations ...

    Indian Academy of Sciences (India)

    first observation was of the transformation of one first integral of the nonlinear ordinary differential equation ... The representative second-order ordinary differential equation of maximal point symmetry, videlicet y = 0,. (2.1) ...... Noetherian Symmetries, Advances in Systems, Signals, Control and Computers,. Bajic VB ed ...

  4. Using frames to determine ordinary meaning in court cases: the ...

    African Journals Online (AJOL)

    Kate H

    Abstract. The South African judicial system has a variety of ways to determine the ordinary meaning of words, ranging from preceding court cases and academic publications to expert witnesses. However, one of the main resources in the interpretation of ordinary words is a dictionary. Much has already been published on ...

  5. Putting It All Together: Integrating Ordinary People Into Emergency Response

    NARCIS (Netherlands)

    Scanlon, J.; Helsloot, I.; Groenendaal, J.

    2014-01-01

    Ordinary citizens may play an important role in the response to large or even small-scale emergencies. This however is often not recognized in the emergency plans and procedures developed by emergency services. As a consequence, the help of ordinary citizens is often underutilized or even rejected

  6. Preventive effect of ordinary and hyperimmune bovine colostrums ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-12-17

    Dec 17, 2008 ... significantly decreased, and serum high density lipoprotein cholesterol (HDL-c) was significantly increased in a .... Preparation of bovine hyperimmune and ordinary colostrum powder .... that received ordinary skim milk powder at the dose of 133.40 mg/kg·bw and served as diabetic control mice, group 3 ...

  7. Sports for learners with physical disabilities in ordinary public ...

    African Journals Online (AJOL)

    In the Western Cape, learners with physical disabilities are accepted into ordinary schools (a school that is not a special school) as a part of the inclusive education initiative. This article reports on a survey designed to determine the types of sports that are available for learners with physical disabilities in ordinary public ...

  8. 7 CFR 28.426 - Strict Good Ordinary Spotted Color.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Strict Good Ordinary Spotted Color. 28.426 Section 28.426 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... Spotted Color. Strict Good Ordinary Spotted Color is color which is within the range represented by a set...

  9. Ordinary differential equations introduction to the theory of ordinary differential equations in the real domain

    CERN Document Server

    Kurzweil, J

    1986-01-01

    The author, Professor Kurzweil, is one of the world's top experts in the area of ordinary differential equations - a fact fully reflected in this book. Unlike many classical texts which concentrate primarily on methods of integration of differential equations, this book pursues a modern approach: the topic is discussed in full generality which, at the same time, permits us to gain a deep insight into the theory and to develop a fruitful intuition. The basic framework of the theory is expanded by considering further important topics like stability, dependence of a solution on a parameter, Car

  10. Possible impact-induced refractory-lithophile fractionations in EL chondrites

    Science.gov (United States)

    Rubin, Alan E.; Huber, Heinz; Wasson, John T.

    2009-03-01

    Literature data show that refractory-lithophile elements in most chondrite groups are unfractionated relative to CI chondrites; the principal exception is the EL-chondrite group whose observed falls (all of which are type 6) are depleted in Ca and light REE. In contrast, literature data and our new INAA data on EL3 PCA 91020, EL3 MAC 88136 and EL4 Grein 002 show that some replicates of these samples have nearly flat REE patterns (unlike those of EL6 chondrites); other replicates exhibit fractionated REE patterns similar to those of EL6 chondrites. Petrographic examination shows that many EL6 (and some EL3 and EL4) chondrites are impact-melt breccias or contain impact-melted portions. We suggest that the same impact processes that formed these breccias and produced melt are responsible for the observed bulk compositional fractionations in refractory-lithophile elements, i.e., EL6 chondrites were produced from initially unequilibrated EL3 material. When large amounts of impact heat were deposited, plagioclase and/or oldhamite (CaS) (the major REE carriers in enstatite chondrites) may have been melted and then transported appreciable (>10 cm) distances. EL6 chondrites represent the residuum that is depleted in REE (particularly in LREE) and Ca. Unlike the case for EL chondrites, our new INAA data on ALH 84170, EET 87746 and SAH 97096 (all EH3) show some scatter but are consistent with the EH group having uniform refractory-lithophile abundances.

  11. Thermomagnetic analysis of meteorites, 3. C3 and C4 chondrites

    Science.gov (United States)

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

    1976-01-01

    Thermomagnetic analysis was made on samples of all known C3 and C4 chondrites in a controlled oxygen atmosphere. Considerable variation was noted in the occurrence of magnetic minerals, comparable to the variation observed earlier in the C2 chondrites. Magnetite was found as the only major magnetic phase in samples of only three C3 chondrites (2-4 wt.%) and the Karoonda C4 chondrite (7.7 wt.%). The magnetite content of these three C3 chondrites is only about one-third that observed in the C1 and C2 chondrites which were found to contain magnetite as the only magnetic phase. Five C3 chondrites were observed to undergo chemical change during heating, producing magnetite: this behavior is characteristic of troilite oxidation. Upper limits on initial magnetite content of about 1-9% were established for these meteorites. Samples of the remaining five C3 chondrites and the Coolidge C4 chondrite were found to contain both magnetite and metallic iron. In two samples, iron containing ???2% Ni was observed, while in the other four, the iron contained 6-8 wt.% Ni. In addition to containing both magnetite and iron metal, three of these samples reacted during heating to form additional magnetite. Variations in the magnetic mineralogy and, hence by inference bulk mineralogy, of C3 and C4 chondrites indicate a more complex genesis than is evident from whole-rock elemental abundance patterns. ?? 1976.

  12. Records of the Moon-forming impact and the 470 Ma disruption of the L chondrite parent body in the asteroid belt from U-Pb apatite ages of Novato (L6)

    Science.gov (United States)

    Yin, Qing-Zhu; Zhou, Qin; Li, Qiu-Li; Li, Xian-Hua; Liu, Yu; Tang, Guo-Qiang; Krot, Alexander N.; Jenniskens, Peter

    2014-08-01

    Novato, a newly observed fall in the San Francisco Bay area, is a shocked and brecciated L6 ordinary chondrite containing dark and light lithologies. We have investigated the U-Pb isotope systematics of coarse Cl-apatite grains of metamorphic origin in Novato with a large geometry ion microprobe. The U-Pb systematics of Novato apatite reveals an upper intercept age of 4472 ± 31 Ma and lower intercept age of 473 ± 38 Ma. The upper intercept age is within error identical to the U-Pb apatite age of 4452 ± 21 Ma measured in the Chelyabinsk LL5 chondrite. This age is interpreted to reflect a massive collisional resetting event due to a large impact associated with the peak arrival time at the primordial asteroid belt of ejecta debris from the Moon-forming giant impact on Earth. The lower intercept age is consistent with the most precisely dated Ar-Ar ages of 470 ± 6 Ma of shocked L chondrites, and the fossil meteorites and extraterrestrial chromite relicts found in Ordovician limestones with an age of 467.3 ± 1.6 Ma in Sweden and China. The lower intercept age reflects a major disturbance related to the catastrophic disruption of the L chondrite parent body most likely associated with the Gefion asteroid family, which produced an initially intense meteorite bombardment of the Earth in Ordovician period and reset and degassed at least approximately 35% of the L chondrite falls today. We predict that the 470 Ma impact event is likely to be found on the Moon and Mars, if not Mercury.

  13. Nuclear track records in the Abee enstatite chondrite

    Science.gov (United States)

    Goswami, J. N.

    1983-01-01

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

  14. New Titanium Monosulfide Mineral Phase in Yamato 691 Enstatite Chondrite

    Science.gov (United States)

    Nakamura-Messenger, K; Clemett, S. J.; Rubin, A. E.; Choi, B.-G.; Zhang, S.; Rahman, Z.; Oikawa, K.; Keller, L. P.

    2011-01-01

    Yamato 691, an EH3 enstatite chondrite, was among the first meteorites discovered by chance in Antarctica by the Japanese Antarctic Research Expedition (JARE) team in 1969. This discovery led to follow-up searches for meteorites in Antarctica [1]. These international searches have been very successful recovering over 40,000 total specimens (and still counting), including martian and lunar meteorites. Titanium is partly chalcophile in enstatite-rich meteorites. Previous occurrences of Ti-bearing sulfides include troilite, daubrelite and ferroan alabandite in enstatite chondrites and aubrites [2], and heideite with 28.5 wt% Ti in the Bustee aubrite [3]. Here we report a new mineral from Yamato 691, ideally stoichiometric TiS, titanium monosulfide, a simple two-element mineral phase, yet with a very unique crystal structure that, to our knowledge, has not been observed previously in nature.

  15. Experimental determination of magnetic characteristics of Kunashak L3 Chondrite

    Science.gov (United States)

    Kim, Hanul; Yu, Yongjae; Ryeol Lee, Seung

    2017-04-01

    A systematic alternating-field (AF) demagnetization on mutually oriented fragments of Kunashak L3 Chondrite was carried out. AF demagnetization spectra for natural remanent magnetization (NRM), anhysteretic remanent magnetization (ARM), and saturation isothermal remanent magnetization (SIRM) were compared. We found that NRM, ARM, and SIRM are controlled by two dominant coercivity fractions, one being in the order of 100 mT, were identified. Higher coercivity fraction was stable whose remanence appears to be carried by Fe-Ni alloys. It is apparent that softer coercivity fraction was governed by the metal-sulfur meting produced by shock metamorphism. Directions of NRM were consistent in mm-scale, implying that brecciation process is responsible for the consistent NRM direction of Kunashak L3 Chondrite.

  16. Chemical studies of H chondrites. 5: Temporal variations of sources

    Science.gov (United States)

    Michlovich, Edward S.; Wolf, Stephen F.; Wang, Ming-Sheng; Vogt, Stephan; Elmore, David; Lipschutz, Michael E.

    1995-01-01

    We report Cl-36 (301-kyr half-life) data obtained by accelerator mass spectrometry allowing nominal terrestrial ages to be determined for 39 Antarctic H4-6 chondrites for which contents of volatile trace elements are known. The compositional difference between these Antarctic meteorites and 58 non-Antarctic falls increases with terrestrial age and, using multivariate statistical techniques, becomes highly significant for Antarctic samples with ages greater than 50 kyr. The compositional difference is inconsistent with trivial causes such as weathering and seems to reflect differences in thermal histories of parent sources. Temporal source variations for the H chondrite flux on Earth thus exist not only on a short-term, 40 years, basis (Dodd et al., 1993) but also on a long-term, greater than 50 kyr, basis.

  17. Chemical characterization of a unique chondrite - Allan Hills 85085

    Science.gov (United States)

    Gosselin, David C.; Laul, J. C.

    1990-01-01

    Allan Hills 85085 is a new and very important addition to the growing list of unique carbonaceous chondrites because of its unique chemical and mineralogical properties. This chemical study provides more precise data on the major, minor, and trace element characteristics of ALH85085. ALH85085 has compositional, petrological, and isotopic affinities to AL Rais and Renazzo, and to Bencubbin-Weatherford. The similarities to Al Rais and Renazzo suggest similar formation locations and thermal processing, possibly in the vicinity of CI chondrites. Petrologic, compositional and isotopic studies indicate that the components that control the abundance of the various refractory and volatile elements were not allowed to equilibrate with the nebula as conditions changed, explaining the inconsistencies in the classification of these meteorites using known taxonomic parameters.

  18. Zoology of condensed matter: framids, ordinary stuff, extra-ordinary stuff

    Science.gov (United States)

    Nicolis, Alberto; Penco, Riccardo; Piazza, Federico; Rattazzi, Riccardo

    2015-06-01

    We classify condensed matter systems in terms of the spacetime symmetries they spontaneously break. In particular, we characterize condensed matter itself as any state in a Poincaré-invariant theory that spontaneously breaks Lorentz boosts while preserving at large distances some form of spatial translations, time-translations, and possibly spatial rotations. Surprisingly, the simplest, most minimal system achieving this symmetry breaking pattern — the framid — does not seem to be realized in Nature. Instead, Nature usually adopts a more cumbersome strategy: that of introducing internal translational symmetries — and possibly rotational ones — and of spontaneously breaking them along with their space-time counterparts, while preserving unbroken diagonal subgroups. This symmetry breaking pattern describes the infrared dynamics of ordinary solids, fluids, superfluids, and — if they exist — supersolids. A third, "extra-ordinary", possibility involves replacing these internal symmetries with other symmetries that do not commute with the Poincaré group, for instance the galileon symmetry, supersymmetry or gauge symmetries. Among these options, we pick the systems based on the galileon symmetry, the " galileids", for a more detailed study. Despite some similarity, all different patterns produce truly distinct physical systems with different observable properties. For instance, the low-energy 2 → 2 scattering amplitudes for the Goldstone excitations in the cases of framids, solids and galileids scale respectively as E 2, E 4, and E 6. Similarly the energy momentum tensor in the ground state is "trivial" for framids ( ρ + p = 0), normal for solids ( ρ + p > 0) and even inhomogenous for galileids.

  19. Unconstrained snoring detection using a smartphone during ordinary sleep

    National Research Council Canada - National Science Library

    Shin, Hangsik; Cho, Jaegeol

    2014-01-01

    .... In contrast with previous studies, we developed a practical technique for snoring detection during ordinary sleep by using the built-in sound recording system of a smartphone, and the recording...

  20. 22 CFR 17.6 - Ordinary and necessary living expenses.

    Science.gov (United States)

    2010-04-01

    ... RETIREMENT AND DISABILITY FUND UNDER THE FOREIGN SERVICE RETIREMENT AND DISABILITY SYSTEM (FSRDS) AND THE FOREIGN SERVICE PENSION SYSTEM (FSPS) § 17.6 Ordinary and necessary living expenses. An individual's...

  1. Stabilization of chromium salt in ordinary portland cement

    Indian Academy of Sciences (India)

    Ordinary Portland cement (OPC) samples containing the chromium salt have been investigated using differential microcalorimetry, conductometry and Fourier transform infrared spectroscopic analysis. The effect of chromium on OPC hydration was evaluated by continuous observing of early hydration.

  2. Timescales and settings for alteration of chondritic meteorites

    Energy Technology Data Exchange (ETDEWEB)

    Krot, A N; Hutcheon, I D; Brearley, A J; Pravdivtseva, O V; Petaev, M I; Hohenberg, C M

    2005-11-16

    Most groups of chondritic meteorites experienced diverse styles of secondary alteration to various degrees that resulted in formation of hydrous and anhydrous minerals (e.g., phyllosilicates, magnetite, carbonates, ferrous olivine, hedenbergite, wollastonite, grossular, andradite, nepheline, sodalite, Fe,Ni-carbides, pentlandite, pyrrhotite, Ni-rich metal). Mineralogical, petrographic, and isotopic observations suggest that the alteration occurred in the presence of aqueous solutions under variable conditions (temperature, water/rock ratio, redox conditions, and fluid compositions) in an asteroidal setting, and, in many cases, was multistage. Although some alteration predated agglomeration of the final chondrite asteroidal bodies (i.e. was pre-accretionary), it seems highly unlikely that the alteration occurred in the solar nebula, nor in planetesimals of earlier generations. Short-lived isotope chronologies ({sup 26}Al-{sup 26}Mg, {sup 53}Mn-{sup 53}Cr, {sup 129}I-{sup 129}Xe) of the secondary minerals indicate that the alteration started within 1-2 Ma after formation of the Ca,Al-rich inclusions and lasted up to 15 Ma. These observations suggest that chondrite parent bodies must have accreted within the first 1-2 Ma after collapse of the protosolar molecular cloud and provide strong evidence for an early onset of aqueous activity on these bodies.

  3. Single-Grain (U-Th)/He Ages of Phosphates from St. Severin Chondrite

    Science.gov (United States)

    Min, K. K.; Reiners, P. W.; Shuster, D. L.

    2010-12-01

    Thermal evolution of chondrites provides valuable information on the heat budget, internal structure and dimensions of their parent bodies once existed before disruption. St. Severin LL6 ordinary chondrite is known to have experienced relatively slow cooling compared to H chondrites. The timings of primary cooling and subsequent thermal metamorphism were constrained by U/Pb (4.55 Ga), Sm/Nd (4.55 Ga), Rb/Sr (4.51 Ga) and K/Ar (4.4 Ga) systems. However, cooling history after the thermal metamorphism in a low temperature range (chlorapatite and fourteen merrillite aggregates from St. Severin, (2) examination of textural and chemical features of the phosphate aggregates using a scanning electron microscope (SEM), and (3) proton-irradiation followed by 4He and 3He diffusion experiments for single grains of chlorapatite and merrillite from Guarena meteorite, for general characterization of He diffusivity in these major U-Th reservoirs in meteorites. The α-recoil-uncorrected ages from St. Severin are distributed in a wide range of 333 ± 6 Ma and 4620 ± 1307 Ma. The probability density plot of these data shows a typical younging-skewed age distribution with a prominent peak at ~ 4.3 Ga. The weighted mean of the nine oldest samples is 4.284 ± 0.130 Ga, which is consistent with the peak of the probability plot. The linear dimensions of the phosphates are generally in the range of ~50 µm to 200 µm. The α recoil correction factor (FT) based on the morphology of the phosphate yields improbably old ages (>4.6 Ga), suggesting that within the sample aggregates, significant amounts of the α particles ejected from phosphates were implanted into the adjacent phases and therefore that this correction may not be appropriate in this case. The minimum FT value of 0.95 is calculated based on the peak (U-Th)/He age and 40Ar/39Ar data which provide the upper limit of the α-recoil-corrected (U-Th)/He ages. From these data, we conclude that the St. Severin cooled through the closure

  4. The Effect of Aqueous Alteration and Metamorphism in the Survival of Presolar Silicate Grains in Chondrites

    Science.gov (United States)

    Trigo-Rodriguez, Josep M.; Blum, Jürgen

    2009-09-01

    Relatively small amounts (typically between 2 and 200 ppm) of presolar grains have been preserved in the matrices of chondritic meteorites. The measured abundances of the different types of grains are highly variable from one chondrite to another, but are higher in unequilibrated chondrites that have experienced little or no aqueous alteration and/or metamorphic heating than in processed meteorites. A general overview of the abundances measured in presolar grains (particularly the recently identified presolar silicates) contained in primitive chondrites is presented. Here we will focus on the most primitive chondrite groups, as typically the highest measured abundances of presolar grains occur in primitive chondrites that have experienced little thermal metamorphism. Looking at the most aqueously altered chondrite groups, we find a clear pattern of decreasing abundance of presolar silicate grains with increasing levels of aqueous alteration. We conclude that measured abundances of presolar grains in altered chondrites are strongly biased by their peculiar histories. Scales quantifying the intensity of aqueous alteration and shock metamorphism in chondrites could correlate with the content of presolar silicates. To do this it would be required to infer the degree of destruction or homogenization of presolar grains in the matrices of primitive meteorites. To get an unbiased picture of the relative abundance of presolar grains in the different regions of the protoplanetary disk where first meteorites consolidated, future dedicated studies of primitive meteorites, IDPs, and collected materials from sample-return missions (like e.g. the planned Marco Polo) are urgently required.

  5. Petrology of Amoeboid Olivine Aggregates in Antarctic CR Chondrites: Evidence for Aqueous Alteration and Shock Metamorphism

    Science.gov (United States)

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

    2017-01-01

    CR chondrites are the group of carbonaceous chondrites that preserve records of formation of their components in the solar nebula. Although they are affected by aqueous alteration, many chondrules and CAIs are well-preserved, suggesting they have experienced little thermal metamorphism. We have been investigating the petrologic variations among the CR chondrites in Japanese-NIPR Antarctic meteorite collection. Especially we focused on the petrology of amoeboid olivine aggregates (AOAs) in order to understand secondary alteration on CR chondrite parent body. AOAs are composed of fine-grained forsteritic olivine and refractory minerals formed by condensation from solar nebula, and can be used as sensitive indicators of secondary alteration processes.

  6. Shock and annealing in the amphibole- and mica-bearing R chondrites

    Science.gov (United States)

    Rubin, Alan E.

    2014-06-01

    MIL 11207 (R6) and LAP 04840 (R6) contain hornblende and phlogopite; MIL 07440 (R6) contains accessory titan-phlogopite and no hornblende. All three meteorites have been shocked: MIL 11207 contains extensive sulfide veins, pyroxene that formed from dehydrated hornblende, and an extensive network of plagioclase glass; MIL 07440 contains chromite-plagioclase assemblages, chromite veinlets and blebs, pincer-shaped plagioclase patches, but no sulfide veins; LAP 04840 contains olivine grains with chromite-bleb-laden cores and opaque-free rims, rare grains of pyroxene that formed from dehydrated hornblende, and no sulfide veins. These meteorites appear to have been heated to maximum temperatures of approximately 700-900 °C under conditions of moderately high PH2O (perhaps 250-500 bars). All three samples underwent postshock annealing. During this process, olivine crystal lattices healed (giving the rocks the appearance of shock-stage S1), and diffusion of Fe and S from thin sulfide veins to coarse sulfide grains caused the veins to disappear in MIL 07440 and LAP 04840. This latter process apparently also occurred in most S1-S2 ordinary chondrites of high petrologic type. The pressure-temperature conditions responsible for forming the amphibole and mica in these rocks may have been present at depths of a few tens of kilometers (as suggested in the literature). A giant impact or a series of smaller impacts would then have been required to excavate the hornblende- and biotite-bearing rocks and bring them closer to the surface. It was in that latter location where the samples were shocked, deposited in a hot ejecta blanket of low thermal diffusivity, and annealed.

  7. Multivariate Statistical Analysis of Labile Trace Elements in H Chondrites: Evidence for Meteoroid Streams

    Science.gov (United States)

    Wolf, S. F.; Lipschutz, M. E.

    1992-07-01

    Differences have been observed between meteorite populations with vastly different terrestrial ages, i.e. Antarctic and non-Antarctic meteorite populations (Koeberl and Cassidy, 1991 and references therein). Comparisons of labile trace element contents (Wolf and Lipschutz, 1992) and induced TL parameters (Benoit and Sears, 1992) in samples from Victoria Land and Queen Maud Land, populations which also differ in mean terrestrial age (Nishiizumi et al, 1989), show significant differences consistent with different average thermal histories. These differences are consistent with the proposition that the flux of meteoritic material to Earth varied temporally. Variations in the flux of meteoritic material over time scales of 10^5 10^6 y require the existence of undispersed streams of meteoroids of asteroidal origin which were initially disputed by Wetherill ( 1986) but have since been observed (Olsson-Steele, 1988; Oberst, 1989; Halliday et al. 1990). Orbital evidence for meteoroid and asteroid streams has been independently obtained by others, particularly Halliday et al.(1990) and Drummond (1991). A group of H chondrites of various petrographic types and diverse CRE ages that yielded 16 falls from 1855 until 1895 in the month of May has been proposed to be two co-orbital meteoroid streams with a common source (R. T. Dodd, personal communication). Compositional evidence of a preterrestrial association of the proposed stream members, if it exists, might be observed in the most sensitive indicators of genetic thermal history, the labile trace elements. We report RNAA data for the concentrations of 14 trace elements, mostly labile ones, (Ag, Au, Bi, Cd, Cs, Co, Ga, In, Rb, Sb, Se, Te, Tl, and Zn) in H4-6 ordinary chondrites. Variance of elemental concentrations within a subpopulation, the members of a proposed co-orbital meteorite stream for example, could be expected to be smaller than the variance for the entire population. We utilize multivariate linear regression and

  8. Petrogenesis of Miller Range 07273, a new type of anomalous melt breccia: Implications for impact effects on the H chondrite asteroid

    Science.gov (United States)

    Ruzicka, Alex M.; Hutson, Melinda; Friedrich, Jon M.; Rivers, Mark L.; Weisberg, Michael K.; Ebel, Denton S.; Ziegler, Karen; Rumble, Douglas; Dolan, Alyssa A.

    2017-09-01

    Miller Range 07273 is a chondritic melt breccia that contains clasts of equilibrated ordinary chondrite set in a fine-grained (shapes for coarse metal grains, unusual internal textures and compositions for coarse metal, a matrix composed chiefly of clinoenstatite and omphacitic pigeonite, and troilite veining most common in coarse olivine and orthopyroxene. These features can be explained by a model involving impact into a porous target that produced brief but intense heating at high pressure, a sudden pressure drop, and a slower drop in temperature. Olivine and orthopyroxene in chondrule clasts were the least melted and the most deformed, whereas matrix and troilite melted completely and crystallized to nearly strain-free minerals. Coarse metal was largely but incompletely liquefied, and matrix silicates formed by the breakdown during melting of albitic feldspar and some olivine to form pyroxene at high pressure (>3 GPa, possibly to 15-19 GPa) and temperature (>1350 °C, possibly to ≥2000 °C). The higher pressures and temperatures would have involved back-reaction of high-pressure polymorphs to pyroxene and olivine upon cooling. Silicates outside of melt matrix have compositions that were relatively unchanged owing to brief heating duration.

  9. The integration (mainstreaming) of spina bifida children into ordinary schools.

    Science.gov (United States)

    Lonton, A P

    1981-12-01

    In 1976, an aggressive policy of integrating spina bifida children into ordinary schools was mounted in Sheffield. Analysis of the school placement pattern of 1235 patients, aged 2-29 years, showed an increase from 25% to 64% integrated for children born in 1968 and 1976, respectively. However, about a half of this 39% increase was attributable to selective non-treatment. The major deterrents to integration were found to be low intelligence and wheelchair dependency. Only 4% of children with IQs below 70 were in ordinary schools. 91% of children with IQs below 45 were in mentally handicapped schools. 88% of children with IQs between 46 and 70 were in physically handicapped schools. 18% of children with wheelchairs only were integrated, and this reduced to 8% if they also had valves and were incontinent. On the other hand, neither incontinence nor valve dependency on their own were major problems with respect to ordinary schooling.

  10. Inverse problems in ordinary differential equations and applications

    CERN Document Server

    Llibre, Jaume

    2016-01-01

    This book is dedicated to study the inverse problem of ordinary differential equations, that is it focuses in finding all ordinary differential equations that satisfy a given set of properties. The Nambu bracket is the central tool in developing this approach. The authors start characterizing the ordinary differential equations in R^N which have a given set of partial integrals or first integrals. The results obtained are applied first to planar polynomial differential systems with a given set of such integrals, second to solve the 16th Hilbert problem restricted to generic algebraic limit cycles, third for solving the inverse problem for constrained Lagrangian and Hamiltonian mechanical systems, fourth for studying the integrability of a constrained rigid body. Finally the authors conclude with an analysis on nonholonomic mechanics, a generalization of the Hamiltonian principle, and the statement an solution of the inverse problem in vakonomic mechanics.

  11. CR chondrites: Shock, aqueous alteration and terrestrial weathering

    Science.gov (United States)

    Abreu, N. M.

    2012-12-01

    CR chondrite are a group asteroidal meteorites, whose importance lies in the exotic organic and presolar material [1] found in its most pristine members and in the broad range of alteration features represented in the remaining specimens in this group [2]. This FE-SEM, EMPA, FIB/TEM study takes advantage of the CR's mineralogical diversity to define different trends of secondary alteration, by comparing the CR3s to the Antarctic CRs: MIL 07525, MIL 07513, GRA 06100, LAP 04516, GRO 03116, GRO 95577, and EET 96259. Collisions and subsequent annealing have affected MIL 07513, GRA 06100, and GRO 03116. Shock stages are often assigned based on progressive changes in the textures of olivines and feldspars. However, the large olivines in shocked CRs do not appear to record these process. Opaques, on the other hand, preserve hallmark signatures of impacts, such as crystalline metal/sulfide veins. Opaque nodules in MIL 07513, GRA 06100, GRO 03116 consist of intergrowths of μm-sub μm FeNi-rich metal, kamacite, Fe-sulfides, Fe-oxides, nm-sized metallic Cu and CuFe (~85 wt.% Cu, 14 wt.% Fe ± LAP 04516, and GRO 95577 show increasing signs of aqueous alteration, such as increasing amounts of ordered phyllosilicates. Although most phyllosilicates are intergrowths of Fe-rich serpentine and saponite, LAP 04516 also contains large (μm-sized), interpenetrating, Fe-rich (cronstedtite-like) phyllosilicates packages with 14Å basal spacings, similar to those observed in CI chondrites by [3]. Heterogeneously interspersed within phyllosilicates are amorphous Fe-rich silicates and small grains (LAP 04516, tochilinite. Tochilinite shows consistent enrichments in Si (~5 wt.%), suggesting that this meteorite has undergone similar pathways of aqueous alteration as CM chondrites [e.g., 4-5]. Despite the myriad of mineralogical changes triggered by secondary and tertiary process affecting the CRs, the relationship between the average S and Fe contents of matrices are good indicators of the

  12. Discovery of Keilite in Type 3 Enstatite Chondrites: Influence of Metamorphic Temperature on Formation

    Science.gov (United States)

    Bullock, E. S.; McCoy, T. J.; Corrigan, C. M.

    2012-03-01

    The discovery of keilite, previously observed in type 4-6 enstatite chondrites, in shock- or impact-melted type 3 enstatite chondrites, constrains the post-shock equilibration temperatures experienced by these meteorites to the range of 400°-500°C.

  13. Zoology of condensed matter: framids, ordinary stuff, extra-ordinary stuff

    Energy Technology Data Exchange (ETDEWEB)

    Nicolis, Alberto; Penco, Riccardo [Physics Department and Institute for Strings, Cosmology, and Astroparticle Physics,Columbia University, New York, NY 10027 (United States); Piazza, Federico [Physics Department and Institute for Strings, Cosmology, and Astroparticle Physics,Columbia University, New York, NY 10027 (United States); Paris Center for Cosmological Physics and Laboratoire APC,Université Paris 7, 75205 Paris (France); CPT, Aix Marseille Université,UMR 7332, 13288 Marseille (France); Rattazzi, Riccardo [Institut de Théorie des Phénomènes Physiques,EPFL Lausanne (Switzerland)

    2015-06-23

    We classify condensed matter systems in terms of the spacetime symmetries they spontaneously break. In particular, we characterize condensed matter itself as any state in a Poincaré-invariant theory that spontaneously breaks Lorentz boosts while preserving at large distances some form of spatial translations, time-translations, and possibly spatial rotations. Surprisingly, the simplest, most minimal system achieving this symmetry breaking pattern — the framid — does not seem to be realized in Nature. Instead, Nature usually adopts a more cumbersome strategy: that of introducing internal translational symmetries — and possibly rotational ones — and of spontaneously breaking them along with their space-time counterparts, while preserving unbroken diagonal subgroups. This symmetry breaking pattern describes the infrared dynamics of ordinary solids, fluids, superfluids, and — if they exist — supersolids. A third, “extra-ordinary”, possibility involves replacing these internal symmetries with other symmetries that do not commute with the Poincaré group, for instance the galileon symmetry, supersymmetry or gauge symmetries. Among these options, we pick the systems based on the galileon symmetry, the “galileids”, for a more detailed study. Despite some similarity, all different patterns produce truly distinct physical systems with different observable properties. For instance, the low-energy 2→2 scattering amplitudes for the Goldstone excitations in the cases of framids, solids and galileids scale respectively as E{sup 2}, E{sup 4}, and E{sup 6}. Similarly the energy momentum tensor in the ground state is “trivial' for framids (ρ+p=0), normal for solids (ρ+p>0) and even inhomogenous for galileids.

  14. A database of chondrite analyses including platinum group elements, Ni, Co, Au, and Cr: Implications for the identification of chondritic projectiles

    National Research Council Canada - National Science Library

    Tagle, Roald; Berlin, Jana

    2008-01-01

    .... To obtain a better knowledge of compositional differences between potential chondritic projectile types, meteorite analyses of the elements Ru, Rh, Pd, Os, Ir, Pt, Cr, Co, Ni, and Au were gathered into a database...

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

    National Research Council Canada - National Science Library

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

    2016-01-01

    The hornblende‐ and biotite‐bearing R chondrite LAP 04840 is a rare kind of meteorite possibly containing outer solar system water stored during metamorphism or postshock annealing deep within an asteroid...

  16. Metastable carbon in two chondritic porous interplanetary dust particles

    Energy Technology Data Exchange (ETDEWEB)

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

    1987-03-12

    An analytical electron microscope study is presented on carbonaceous material in two chondritic porous aggregates, W7029* A and W7010* A2, from the Johnson Space Center Cosmic Dust Collection. The finding of well-ordered carbon-2H (lonsdaleite) in the two aggregates suggests that a record of hydrocarbon carbonization may be preserved in these materials. This carbon is a metastable phase resulting from hydrous pyrolysis below 300-350/sup 0/C and may be a precursor to poorly graphitized carbons in primitive extra terrestrial materials.

  17. The Melnikovo LL6 chondrite - A new find from Ukraine

    Science.gov (United States)

    Krot, A. N.; Zaslavskaia, N. I.; Petaev, M. I.; Kononkova, N. N.; Barsukova, L. D.; Kolesov, G. M.

    1992-06-01

    Melnikovo is a relatively unweathered 545.6-g LL6 chondrite that was found in 1983. Only a few poorly defined chondrules are discernable in the examined sections; two of these are enriched in chromite. The meteorite contains olivine (Fa(27.8)), low-Ca pyroxene (Fs(24.4)), plagioclase, rare clinopyroxene, chlorapatite, merrillite, and opaque minerals, which have a modal abundance (in wt pct) of troilite (3.9 pct), kamacite (0.4 pct), taenite plus tetrataenite (0.7 pct), chromite (0.8 pct), and trace amounts of ilmenite and Mn-ilmenite. The meteorite appears unbrecciated on a centimeter scale.

  18. Ubiquitous interstellar diamond and SiC in primitive chondrites - Abundances reflect metamorphism

    Science.gov (United States)

    Huss, Gary R.

    1990-01-01

    It is shown here that interstellar diamond and SiC were incorporated into all groups of chondrite meteorites. Abundances rapidly go to zero with increasing metamorphic grade, suggesting that metamorphic destruction is responsible for the apparent absence of these grains in most chondrites. In unmetamorphosed chondrites, abundances normalized to matrix content are similar for different classes. Diamond samples from chondrites of different classes have remarkably similar noble-gas constants and isotropic compositions, although constituent diamonds may have come from many sources. SiC seems to be more diverse, partly because grains are large enough to measure individually, but average characteristics seem to be similar from meteorite to meteorite. These observations suggest that various classes of chondritic meteorites sample the same solar system-wide reservoir of interstellar grains.

  19. The formation of Ca-, Fe-rich silicates in reduced and oxidized CV chondrites: The roles of impact-modified porosity and permeability, and heterogeneous distribution of water ices

    Science.gov (United States)

    MacPherson, Glenn J.; Krot, Alexander N.

    2014-07-01

    CV (Vigarano type) carbonaceous chondrites, comprising Allende-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 chondrites 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 chondrites, and carbonates in CI, CM, and CR chondrites are consistent with aqueous alteration initiated by heating of water ice-bearing asteroids by decay of 26Al, not shock metamorphism.

  20. Ordinary people and emotional expression in Dutch public service news

    NARCIS (Netherlands)

    Pantti, M.; Husslage, K.

    2009-01-01

    In news broadcasts, there is a growing tendency to rely on the voices of ordinary people in comparison with offi cial voices, such as media professionals and experts. In our study, which is based on a quantitative and qualitative content analysis and interviews with journalists, we look at the vox

  1. To the boundary value problem of ordinary differential equations

    Directory of Open Access Journals (Sweden)

    Serikbai Aisagaliev

    2015-09-01

    Full Text Available Method for solving of a boundary value problem for ordinary differential equations with boundary conditions at phase and integral constraints is proposed. The base of the method is an immersion principle based on the general solution of the first order Fredholm integral equation which allows to reduce the original boundary value problem to the special problem of the optimal equation.

  2. "Solid All the Way Through": Margaret Mahy's Ordinary Witches

    Science.gov (United States)

    Waller, Alison

    2004-01-01

    In "The Haunting," "The Changeover," and "The Tricksters," Margaret Mahy fuses supernatural iconography of witchcraft and magic with images of ordinary and domestic adolescence. This article argues that Mahy's "fantastic realism" illuminates aspects of female teenage experience through a blend of myth, fairy tale, folklore and history, as well as…

  3. Comparative study of the properties of ordinary portland cement ...

    African Journals Online (AJOL)

    The study explored metakaolin as alternative material to cement. It compares the properties of Ordinary Portland Cement (OPC) concrete and binary concrete containing metakaolin as partial replacement of OPC. Two set of concrete samples; one with 10% Metakaolin (MK) replacing OPC by weight, and the other without ...

  4. Numerical Integration of Stiff System of Ordinary Differential ...

    African Journals Online (AJOL)

    The goal of this work is to develop, analyse and implement a K-step Implicit Rational Runge-Kutta schemes for Integration of Stiff system of Ordinary differential Equations. Its development adopted Taylor and Binomial series expansion Techniques to generate its parameters. The analysis of its basic properties adopted ...

  5. Preventive effect of ordinary and hyperimmune bovine colostrums ...

    African Journals Online (AJOL)

    In the present study, the anti-diabetic effect of ordinary and hyperimmune bovine colostrum were evaluated in diabetic mice induced by alloxan. The results indicated that blood glucose levels were significantly decreased after administration of colostrum for 30 d, and the glucose tolerance was strengthened in a ...

  6. An accurate scheme by block method for third order ordinary ...

    African Journals Online (AJOL)

    A block linear multistep method for solving special third order initial value problems of ordinary differential equations is presented in this paper. The approach of collocation approximation is adopted in the derivation of the scheme and then the scheme is applied as simultaneous integrator to special third order initial value ...

  7. Radiative transitions from the psi (3095) to ordinary hadrons

    Energy Technology Data Exchange (ETDEWEB)

    Scharre, D.L.

    1980-05-01

    Preliminary results from the Mark II and Crystal Ball experiments on radiative transitions from the psi to ordinary hadrons are presented. In additon to the previously observed transitions to the eta, eta'(958), and f(1270), both groups observe a transition to a state which is tentatively identified as the E(1420).

  8. Ordinary Differential Equations -- Lecture Notes 2014-2015

    NARCIS (Netherlands)

    W. Hundsdorfer (Willem)

    2014-01-01

    htmlabstractIn these notes we study the basic theory of ordinary differential equations, with emphasis on initial value problems, together with some modelling aspects. The following topics are treated: 1. Models and Explicit Solutions, 2. Existence and Uniqueness, 3. Linear Systems, 4.

  9. Learning to Compute: Computerization and Ordinary, Everyday Life

    Science.gov (United States)

    Sullivan, Joseph F.

    2009-01-01

    This study utilizes the basic framework of classical sociology as a foundation for examining the intersection of the structural history of the computer revolution with ordinary, everyday life. Just as the classical forefathers of modern sociology--Marx, Durkheim, and Weber--attempted to understand their eras of structural transformation, this…

  10. Pulsed-Laser Irradiation Space Weathering Of A Carbonaceous Chondrite

    Science.gov (United States)

    Thompson, M. S.; Keller, L. P.; Christoffersen, R.; Loeffler, M. J.; Morris, R. V.; Graff, T. G.; Rahman, Z.

    2017-01-01

    Grains on the surfaces of airless bodies experience irradiation from solar energetic particles and melting, vaporization and recondensation processes associated with micrometeorite impacts. Collectively, these processes are known as space weathering and they affect the spectral properties, composition, and microstructure of material on the surfaces of airless bodies, e.g. Recent efforts have focused on space weathering of carbonaceous materials which will be critical for interpreting results from the OSIRIS-REx and Hayabusa2 missions targeting primitive, organic-rich asteroids. In addition to returned sample analyses, space weathering processes are quantified through laboratory experiments. For example, the short-duration thermal pulse from hypervelocity micrometeorite impacts have been simulated using pulsed-laser irradiation of target material e.g. Recent work however, has shown that pulsed-laser irradiation has variable effects on the spectral properties and microstructure of carbonaceous chondrite samples. Here we investigate the spectral characteristics of pulsed-laser irradiated CM2 carbonaceous chondrite, Murchison, including the vaporized component. We also report the chemical and structural characteristics of specific mineral phases within the meteorite as a result of pulsed-laser irradiation.

  11. Intriguing Dehydrated Phyllosilicates Found in an Unusual Clast in the LL3.15 Chondrite NWS6925

    Science.gov (United States)

    Johnson, Jessica M.; Zolensky, Michael E.; Chan, Queenie; Kring, David A.

    2016-01-01

    Meteorites provide us with valuable insights into the conditions of the early solar system. Collisions often occur in our solar system that can result in materials accreting to other bodies as foreign clasts. These foreign pieces may have multiple origins that can sometimes be easily identified as a particular type of meteorite. It is important to interpret the origins of these clasts in order to understand dynamics of the solar system, especially throughout its early history. The Nice Model, as modified, proposes a reordering of planetary orbits that is hypothesized to have triggered the Late Heavy Bombardment. Clasts found within meteorites that came from objects in the solar system not commonly associated as an impactor could be indicative of such an event suggested by the Nice Model. Impacts also redistribute material from one region of an asteroid to another, and so clasts are found that reveal portions of the geological history of a body that are not recorded by typical samples. These would be cognate clasts. The goal of this investigation was to examine meteorites that had particularly interesting foreign and cognate clasts enclosed in them. We focus here on an unusual clast located in the ordinary chondrite, NWA 6925. This is one of three clasts analyzed during the LPI summer internship of Jessica Johnson.

  12. Insights into chondrule formation process and shock-thermal history of the Dergaon chondrite (H4-5

    Directory of Open Access Journals (Sweden)

    D. Ray

    2017-05-01

    Full Text Available The Dergaon fall represents a shock-melted H4-5 (S5 ordinary chondrite which includes at least ten textural varieties of chondrules and belongs to the high chondrule-matrix ratio type. Our study reveals that the chondrules are of diverse mineralogy with variable olivine-pyroxene ratios (Type II, igneous melt textures developed under variable cooling rates and formed through melt fractionations from two different melt reservoirs. Based on the experimental analogues, mineralogical associations and phase compositions, it is suggested that the Dergaon chondrules reflect two contrasting environments: a hot, dust-enriched and highly oxidized nebular environment through melting, without significant evaporation, and an arrested reducing environment concomitant with major evaporation loss of alkali and highly volatile trace elements. Coexistence of chlorapatite and merrillite suggests formation of the Dergaon matrix in an acidic accretionary environment. Textural integration and chemical homogenization occurred at ∼1 atmospheric pressure and a mean temperature of 765 °C mark the radiogenic thermal event. Equilibrated shock features (olivine mosaicism, diaplectic plagioclase, polycrystalline troilite due to an impact-induced thermal event reflect a shock pressure >45 GPa and temperature of 600 °C. By contrast, the local disequilibrium shock features (silicate melt veins comprising of olivine crystallites, troilite melt veins and metal droplets correspond to a shock pressure up to 75 GPa and temperature >950 °C.

  13. Ordinary differential equations with applications in molecular biology.

    Science.gov (United States)

    Ilea, M; Turnea, M; Rotariu, M

    2012-01-01

    Differential equations are of basic importance in molecular biology mathematics because many biological laws and relations appear mathematically in the form of a differential equation. In this article we presented some applications of mathematical models represented by ordinary differential equations in molecular biology. The vast majority of quantitative models in cell and molecular biology are formulated in terms of ordinary differential equations for the time evolution of concentrations of molecular species. Assuming that the diffusion in the cell is high enough to make the spatial distribution of molecules homogenous, these equations describe systems with many participating molecules of each kind. We propose an original mathematical model with small parameter for biological phospholipid pathway. All the equations system includes small parameter epsilon. The smallness of epsilon is relative to the size of the solution domain. If we reduce the size of the solution region the same small epsilon will result in a different condition number. It is clear that the solution for a smaller region is less difficult. We introduce the mathematical technique known as boundary function method for singular perturbation system. In this system, the small parameter is an asymptotic variable, different from the independent variable. In general, the solutions of such equations exhibit multiscale phenomena. Singularly perturbed problems form a special class of problems containing a small parameter which may tend to zero. Many molecular biology processes can be quantitatively characterized by ordinary differential equations. Mathematical cell biology is a very active and fast growing interdisciplinary area in which mathematical concepts, techniques, and models are applied to a variety of problems in developmental medicine and bioengineering. Among the different modeling approaches, ordinary differential equations (ODE) are particularly important and have led to significant advances

  14. Mineralogical, Spectral, and Compositional Changes During Heating of Hydrous Carbonaceous Chondrites

    Science.gov (United States)

    Nakamura, T.; Matsuoka, M.; Yamashita, S.; Sato, Y.; Mogi, K.; Enokido, Y.; Nakata, A.; Okumura, S.; Furukawa, Y.; Zolensky, M.

    2017-01-01

    Hydrous carbonaceous chondrites experienced hydration and subsequent dehydration by heating, which resulted in a variety of mineralogical and spectral features [e. g., 1-6]. The degree of heating is classified according to heating stage (HS) II to IV based on mineralogy of phyllosilicates [2], because they change, with elevating temperature, to poorly crystal-line phases and subsequently to aggregates of small secondary anhydrous silicates of mainly olivine. Heating of hydrous carbonaceous chondrites also causes spectral changes and volatile loss [3-6]. Experimental heating of Murchison CM chondrite showed flattening of whole visible-near infrared spectra, especially weakening of the 3µm band strength [1, 4, 7]. In order to understand mineralogical, spectral, and compositional changes during heating of hydrous carbonaceous chondrites, we have carried out systematic investigation of mineralogy, reflectance spectra, and volatile composition of hydrated and dehydrated carbonaceous chondrites as well as experimentally-heated hydrous carbonaceous chondrites. In addition, we investigated reflectance spectra of tochilinite that is a major phase of CM chondrites and has a low dehydration temperature (250degC).

  15. Gallium and germanium in the metal and silicates of L- and LL-chondrites.

    Science.gov (United States)

    Chou, C.-L.; Cohen, A. J.

    1973-01-01

    Concentrations of Ga and Ge in the metal of 31 L-, 8 LL- and 2 H-chondrites, and in the silicates of 12 L- and LL-chondrites have been determined by spectrophotometric methods. The ranges of Ga contents in the metal of L- and LL-chondrites are 1.1 to 36.9 ppm and 1.0 to 34.1 ppm, respectively. The Ge content in the metal is positively correlated with Ga and ranges from 89.1 to 160 ppm and from 126 to 308 ppm for L- and LL-chondrites, respectively. The Ga content in the silicates of L-chondrites varies from 4.0 to 8.9 ppm. The Ga and Ge contents in the metal are clearly lower in unequilibrated than in equilibrated L- and LL-group chondrites. Unequilibrated and equilibrated chondrites are well separated in the plots of Ga vs Ge in the metal, and the L- and LL-groups are also well resolved. The Ga and Ge in the metal are well correlated with petrologic grade. This suggests that Ga and Ge variations in the metal are related to thermal metamorphism. There is evidence of an enrichment of Ga in the metal due to shock reheating.

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

    Science.gov (United States)

    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.

  17. The Comparative Analysis of Aversive and Ordinary Noise.

    Science.gov (United States)

    Mobley, C. Marion, Jr.

    There is a vast amount of literature concerning the psychological and physiological effects of ordinary noise on the individual. However, few publications have addressed the analysis of aversive noise. This research analyzes three noises which produce the familiar goose flesh or chilling effect responsivity. These aversive sounds which are made by chalk squeaking on the chalkboard, fingernails on the chalkboard and rubbing styrofoam against a smooth surface are digitally compared to ordinary noise to show how these aversive sounds differ from sounds which are only annoying. This work, which uses Fast Fourier Transform (FFT) analysis is a combination with cross correlation analysis and other innovative methods to produce comparative data on noises, illustrates subtle differences between ordinary and aversive noise which may be useful for future work in acoustics or experimental psychology. The literature review shows disagreement among the numerous works on the effects of ordinary noise on human subjects. One explanation for this difference is the failure to adequately measure and define the dynamic nature of the noise used. The existing literature also establishes that a mixture of tones plus random noise is more annoying (but not aversive) than either the random noise or the tones alone. This investigation shows that one property of aversive noises is the combination of randomness plus tones which vary rapidly with time. This paper utilizes a new digital technique which improves the FFT analyzer resolution by a factor of 25. The resulting +/-2 Hz accuracy facilitated the presentation of frequency variation as a function of time data. Other computer generated graphical data includes the percent harmonic deviation as a function of time, the rate of change of fundamental frequency, and the rate of change in harmonic deviation. From these dynamic data, average values are calculated which show the aversive noise to be consistently greater in mean frequency deviation

  18. In situ analysis of Refractory Metal Nuggets in carbonaceous chondrites

    Science.gov (United States)

    Daly, Luke; Bland, Phil A.; Dyl, Kathryn A.; Forman, Lucy V.; Evans, Katy A.; Trimby, Patrick W.; Moody, Steve; Yang, Limei; Liu, Hongwei; Ringer, Simon P.; Ryan, Christopher G.; Saunders, Martin

    2017-11-01

    Micrometre to sub-micrometre-scale alloys of platinum group elements (PGEs) known as Refractory Metal Nuggets (RMNs) have been observed in primitive meteorites. The Australian Synchrotron X-ray Fluorescence (XRF) beamline, in tandem with the Maia detector, allows rapid detection of PGEs in concentrations as low as 50-100 ppm at 2 μm resolution. Corroborating these analyses with traditional electron microscopy techniques, RMNs can be rapidly identified in situ within carbonaceous chondrites. These results dispute the assumption of most previous studies: that RMNs are unique to Ca-Al-rich inclusions (CAIs). We find that RMNs are, in fact, observed within all components of carbonaceous chondrites, such as the matrix, chondrules (consistent with observations from Schwander et al. (2015b) and Wang et al. (2007)), and sulphides; though the majority of RMNs are still found in CAIs. The chemistry of RMNs reveals a complex diversity of compositions, which nevertheless averages to CI chondrite abundance ratios. This implies that RMNs are the dominant, if not sole host phase for PGEs. One hundred and thirteen RMNs from this study are combined with reported compositions in the literature, and compared to condensation model compositions similar to Berg et al. (2009), RMNs derived experimentally by precipitation (Schwander et al., 2015a), host phase and host meteorite. Comparisons reveal only weak correlations between parent body processes (sulphidation) and nebular processes (condensation and precipitation) with RMN compositions. It appears that none of these processes acting in isolation or in tandem can explain the diversity observed in the RMN population. Our interpretation is that the Solar Nebula inherited an initially compositionally diverse population of RMNs from the Giant Molecular Cloud; that a variety of Solar System processes have acted on that population; but none have completely homogenised it. Most RMNs have experienced disk and asteroidal processing, but some

  19. The Mukundpura meteorite, a new fall of CM chondrite

    Science.gov (United States)

    Ray, Dwijesh; Shukla, Anil D.

    2018-02-01

    Mukundpura is a new CM chondrite fell near Jaipur, Rajasthan, India on June 6, 2017 at 5:15 IST. The fall was observed by local villager. According to eyewitness, the meteorite was fragmented into several pieces once the object hit the ground. Based on petrography, mineralogy and bulk composition, Mukundpura is classified as CM2 chondrite. The chondrules are mainly similar to type I (Olivine: Fo99). Olivines are often found associated with pyroxene (Wo10-35En62-87Fs2-7) phenocryst. However, occurrences of forsteritic and fayalitic olivine (Fa58-71) as isolated mineral clast in matrix are not uncommon. Other types of chondrules include porphyritic pyroxene (En86Fs14) and barred olivine (Fa32.7±0.3) clast. Chondrules are commonly rimmed by fine-grained accretionary dust mantles. Phyllosilicates are the most dominant secondary mineral in matrix and largely associated with poorly characterised phases (PCP). FeO/SiO2 and S/SiO2 of PCP are 2.7 and 0.4 respectively. Other phases in matrix generally include calcite (pure CaCO3), Fe-Ni metal and sulphides. Spinel and perovskite occur occasionally as inclusions. The spherical or elliptical shaped metals (within chondrule or in isolated grains) are low-Ni type (kamacite <7.5 wt%) and resembles the solar Ni/Co ratio. However, Ni content in metal rarely exceeds 8.5 wt% (up to 23 wt%, taenite). Pyrrhotite (Fe ∼62 wt%; S ∼38 wt%) and pentlandite (Fe ∼31-33 wt%, Ni ∼28-32 wt%, S ∼33 wt%)) are the common sulphides occur as isolated grains within the matrix, however, the former is the most dominant. The bulk chemical composition of Mukundpura is largely similar to other CM type chondrite (e.g. Paris CM). Based on petrography, we infer a modest aqueous alteration stage for Mukundpura while the effect of thermal metamorphism was negligible.

  20. The Fountain Hills Meteorite: A New CB(a) Chondrite from Arizona

    Science.gov (United States)

    Lauretta, D. S.; Killgore, M.; Greenwood, R. C.; Verchovsky, A. B.; Franchi, I. A.

    2004-01-01

    The CR clan of meteorites has been established and a detailed review of these meteorites is presented. There are several kinds of carbonaceous chondrites included in this clan: Carbonaceous Renazzo-like (CR), Carbonaceous with High metal (CH), Carbonaceous Bencubbin-like (CB), and LEW 85332, a unique-metal rich meteorite. The CB chondrites are further divided into two subgroups: CB(sub a) and CB(sub b). Here we describe a new member of the CR chondrite clan, Fountain Hills, a recent find with a total mass of approximately 60 g.

  1. Pb-Pb dating of individual chondrules from the CBa chondrite Gujba

    DEFF Research Database (Denmark)

    Bollard, Jean Francois André; Connelly, James; Bizzarro, Martin

    2015-01-01

    The CB chondrites are metal-rich meteorites with characteristics that sharply distinguish them from other chondrite groups. Their unusual chemical and petrologic features and a young formation age of bulk chondrules dated from the CBa chondrite Gujba are interpreted to reflect a single......-behaved Pb-Pb systematics of all four chondrules, a precise formation age and the concordancy of the Mn-Cr, Hf-W, and I-Xe short-lived radionuclide relative chronometers, we propose that Gujba may serve as a suitable time anchor for these systems....

  2. The Nature of C Asteroid Regolith Revealed from the Jbilet Winselwan CM Chondrite

    Science.gov (United States)

    Zolensky, Michael; Mikouchi, Takashi; Hagiya, Kenji; Ohsumi, Kazumasa; Komatsu, Mutsumi; Chan, Queenie H. S.; Le, Loan; Kring, David; Cato, Michael; Fagan, Amy L.

    2016-01-01

    C-class asteroids frequently exhibit reflectance spectra consistent with thermally metamorphosed carbonaceous chondrites, 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 chondrites, but has rarely been considered a major process for hydrous carbonaceous chondrites.

  3. The early solar system abundance of /sup 244/Pu as inferred from the St. Severin chondrite

    Energy Technology Data Exchange (ETDEWEB)

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

    1987-03-01

    We describe the analysis of Xe released in stepwise heating of neutron-irradiated samples of the St. Severin chondrite. This analysis indicates that at the time of formation of most chondritic meteorites, approximately 4.56 x 10/sup 9/ years ago, the atomic ratio of /sup 244/Pu//sup 238/U was 0.0068 +- 0.0010 in chondritic meteorites. We believe that this value is more reliable than that inferred from earlier analyses of St. Severin. We feel that this value is currently the best available estimate for the early solar system abundance of /sup 244/Pu. 42 refs., 2 tabs.

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

    Science.gov (United States)

    Horstmann, Marian; Humayun, Munir; Bischoff, Addi

    2014-09-01

    Enstatite (E) chondrites are a group of texturally highly variable meteorites formed under strongly reducing conditions giving rise to unique mineral and chemical characteristics (e.g., high abundances of various sulfides and Si-bearing metal). In particular the abundant metal comprises a range of textures in E chondrites of different petrologic type, but available in situ siderophile trace element data on metal are limited. Nine samples of E chondrites from the recent Almahata Sitta fall [one EH3, two EL3/4, two EL6, two EL impact melt rocks (IMR), two EH IMR] were investigated in this study in addition to St. Mark's (EH5) and Grein 002 (EL4/5), with a focus on the nature of their metal constituents. Special attention was given to metal-silicate intergrowths (MSSI) that occur in many primitive E chondrites, which have been interpreted as post-accretionary asteroidal impact melts or primitive nebular condensates. This study shows that siderophile trace element systematics in E chondrite metal are independent of petrologic type of the host rock and distinct from condensation signatures. Three basic types of siderophile trace element signatures can be distinguished, indicating crystallization from a melt, thermal equilibration upon metamorphism/complete melting, and exsolution of schreibersite-perryite-sulfide. Textural and mineral-chemical constraints from EL3/4s are used to evaluate previously proposed formation processes of MSSI (impact melting vs. nebular condensation) and elucidate which other formation scenarios are feasible. It is shown that post-accretionary (in situ) impact melting or metallic melt injection forming MSSI on the thin section scale, and nebular condensation, are unlikely formation processes. This leads to the conclusion that MSSIs are pre-accretionary melt objects that were formed during melting processes prior to the accretion of the primitive E chondrites. The same can be concluded for metal nodules in the EH3 chondrite examined. The pre

  5. Children’s Understanding of Ordinary and Extraordinary Minds

    Science.gov (United States)

    Lane, Jonathan D.; Wellman, Henry M.; Evans, E. Margaret

    2014-01-01

    How and when do children develop an understanding of extraordinary mental capacities? Fifty-six preschoolers (3-5 years old) were tested on false-belief and knowledge-ignorance tasks about the mental states of carefully contrasted agents – some agents were ordinary humans, some had exceptional perceptual capacities, and others possessed extraordinary mental capacities. Results indicated that, in contrast with younger and older peers, children within a specific age-range reliably attributed fallible, human-like capacities to ordinary humans and to several special agents (including God) for both tasks. These data lend critical support to an anthropomorphism hypothesis – which holds that children’s understanding of extraordinary minds is derived from their everyday intuitive psychology – and reconcile disparities between the findings of other studies on children’s understanding of extraordinary minds. PMID:20840235

  6. Heterogeneous plagioclase compositions in the Maralinga CK4 chondrite

    Science.gov (United States)

    Keller, Lindsay P.

    1993-01-01

    One of the characteristic features of CK chondrites is the wide compositional range displayed by feldspar grains in matrix relative to the narrow range of compositions exhibited by the highly equilibrated olivines and pyroxenes. Recently, it was suggested that these heterogeneous feldspar compositions may have been strongly influenced by shock metamorphisms. It is shown that the apparent range of feldspar compositions in Maralinga probably results from annealing during parent body thermal metamorphism rather than shock. The majority of matrix feldspars in Maralinga are typically 50 microns in size and are compositionally zoned, with oligoclase cores (approximately An40) and bytownite rims (approximately An80). The contact between core and rim is sharp and abrupt and is readily observed in backscattered scanning electron microscopy (SEM) images.

  7. Nullarbor 018: A new L6 chondrite from Australia

    Science.gov (United States)

    Ruzicka, Alex

    1995-01-01

    A new meteorite find from the Nullarbor Plain in Australia was studied using optical, scanning electron microscopy (SEM), and electron microprobe techniques. The meteorite, Nullarbor 018, is an orthodox L6 chondrite that experienced minor-to-moderate alteration of metal during terrestrial weathering (grade A-B to B). During weathering, trolite was preferentially altered, and roughly 20% of the original complement of S in the meteorite was removed. Shock metamorphic effects corresponding to shock stage S4 (or shock facies d) are found, including the presence of some diaplectic feldspar (maskelynite). The meteorite is not obviously paired with other finds from the Nullarbor region, but the possibility that it is paired cannot be excluded.

  8. Hypothesis Testing of Parameters for Ordinary Linear Circular Regression

    Directory of Open Access Journals (Sweden)

    Abdul Ghapor Hussin

    2006-07-01

    Full Text Available This paper presents the hypothesis testing of parameters for ordinary linear circular regression model assuming the circular random error distributed as von Misses distribution. The main interests are in testing of the intercept and slope parameter of the regression line. As an illustration, this hypothesis testing will be used in analyzing the wind and wave direction data recorded by two different techniques which are HF radar system and anchored wave buoy.

  9. The Significance of Information in the Ordinary Conduct of Life

    Directory of Open Access Journals (Sweden)

    Robert Newhard

    1981-06-01

    Full Text Available The information benefit provided to the general public by the developing telecommunications systems will be highly dependent upon the provider's perception of the current and potential role of information in the ordinary interests of life. Assessing this role cannot easily be done by standard questionnaire or survey methods because information does not have a conscious function in people's lives. Some paradigms from the past and present may, therefore, be of use in articulating the everyday importance of information.

  10. Ultra-Refractory Calcium-Aluminum-Rich Inclusion in an AOA in CR Chondrite Yamato-793261

    Science.gov (United States)

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

    2017-01-01

    CR chondrites are a group of primitive carbonaceous chondrites that preserve nebular records of the formation conditions of their components. We have been investigating a set of Antarctic CR chondrites from the Japanese-NIPR collection in order to study variations within this group. During our study, we have found an AOA that encloses an ultrarefractory (UR) CAI in Yamato-793261 (Y-793261). UR CAIs are rare in carbonaceous chondrites, and only three UR CAIs in AOAs have been identified so far. UR CAIs can provide information on crystallization processes at very high temperatures in the solar nebula. Here we describe the petrology of Y-793261, and preliminary results on this newly discovered AOA enclosing a UR CAI.

  11. New Insights into the Composition of Wax-Like Materials in Chondrites

    Science.gov (United States)

    Krebsz, M.; Garenne, A.; Quirico, E.; Bonal, L.; Beck, P.; Vuitton, V.; Thissen, R.; Flandinet, L.; Schmitt, B.; Kereszturi, A.

    2013-09-01

    Our study aims to extract wax-like compounds from a series of carbonaceous chondrites in order to perform a combined characterization by IR, Raman and NMR spectroscopies, and secondary ion mass spectrometry.

  12. Cohenite in Chondrites: Further Support for a Shock-Heating Origin

    Science.gov (United States)

    Likkel, L.; Ruzicka, A. M.; Hutson, M.; Schepker, K.; Yeager, T.

    2013-09-01

    In thin sections of two chondrites, cohenite was found with optical microscopy to be preferentially near shock melt or in heat affected host. This is consistent with cohenite formation due to contact metamorphism from heating by nearby shock melt.

  13. Thermal Alteration of CI and CM Chondrites: Mineralogical Changes and Metamorphic Temperatures

    Science.gov (United States)

    King, A. J.; Schofield, P. F.; Russell, S. S.

    2015-07-01

    Modal mineralogy, H2O abundances and spectral features are used to constrain the origin of thermally altered CI and CM chondrites. Heterogeneous heating was probably caused by impact shocks and affected the surfaces of many C-type asteroids.

  14. Ringwoodite Rims Around Olivine Fragments in Melt Vein of Antarctic Chondrite GRV 022321: Transformation Kinetics

    Science.gov (United States)

    Xie, Z.; Li, X.; Sharp, T. G.; DeCarli, P. S.

    2013-09-01

    Ringwoodite rims around olivine in shocked veins of chondrites GRV 022321 were investigated by electron microscopes to elucidate mechanisms of transformation and Mg-Fe diffusion of olivine to ringwoodite, and estimate shock duration using kinetics.

  15. Ringwoodite Microstructures in L-Chondrites RC 106 and Acfer 040: Implications for Transformation Mechanisms

    Science.gov (United States)

    Sharp, T. G.; Trickey, R.; Xie, Z.; de Carli, P. S.

    2009-03-01

    The transformation of olivine to ringwoodite is important because the transformation kinetics can be used to constrain shock duration. Here we examine the microstructures in ringwoodites from L chondrites RC106 and Acfer040 to better understand transformation mechanisms.

  16. Cumberland Falls chondritic inclusions. III - Consortium study of relationship to inclusions in Allan Hills 78113 aubrite

    Science.gov (United States)

    Lipschutz, Michael E.; Verkouteren, R. Michael; Sears, Derek W. G.; Hasan, Fouad A.; Prinz, Martin

    1988-01-01

    The contents of Ag, Au, Bi, Cd, Co, Cs, Ga, In, Rb, Sb, Se, Te, Tl, U, and Zn in large chondritic clasts from the Cumbersand Falls aubrite were determined by radiochemical neutron activation analysis, and the results, together with the results of a mineralogical investigation, were compared with respective data obtained for three primitive inclusions from the ALH A78113 aubrite. The results indicated that the clasts from both aubrite sources constitute a single chondritic suite. The analyses data, together with the results of thermoluminescence data for Cumberland Falls chondritic inclusions and achondritic host, indicate that inclusions in Cumberland Falls and in ALH A78113 aubrite represent a primitive chondrite sample suite whose properties were established during primary nebular accretion and condensation over a broad redox range.

  17. Studies of Brazilian meteorites. XIV - Mineralogy, petrology, and chemistry of the Conquista, Minas Gerais, chondrite

    Science.gov (United States)

    Keil, K.; Kirchner, E.; Gomes, C. B.; Jarosewich, E.; Murta, R. L. L.

    1978-01-01

    The Conquista chondrite is described and classified as an H4. The mineral composition is reported. H-group classification is based on described microscopic, electron microprobe, and bulk chemical studies. The evidence for petrologic type 4 classification includes the pronounced well-developed chondritic texture; the slight compositional variations in constituent phases; the high Ca contents of pyroxene and the presence of pigeonite; glassy to microcrystalline interstitial material rich in alkalis and SiO2; and twinned low-Ca clinopyroxene.

  18. 76 FR 40451 - Agency Information Collection (Application for Ordinary Life Insurance) Activity Under OMB Review

    Science.gov (United States)

    2011-07-08

    ... AFFAIRS Agency Information Collection (Application for Ordinary Life Insurance) Activity Under OMB Review... INFORMATION: Titles a. Application for Ordinary Life Insurance, Replacement Insurance for Modified Life Reduced at Age 65, National Service Life Insurance, VA Form 29-8485. b. Application for Ordinary Life...

  19. A unique transformation from ordinary differential equations to reaction networks.

    Directory of Open Access Journals (Sweden)

    Sylvain Soliman

    Full Text Available Many models in Systems Biology are described as a system of Ordinary Differential Equations, which allows for transient, steady-state or bifurcation analysis when kinetic information is available. Complementary structure-related qualitative analysis techniques have become increasingly popular in recent years, like qualitative model checking or pathway analysis (elementary modes, invariants, flux balance analysis, graph-based analyses, chemical organization theory, etc.. They do not rely on kinetic information but require a well-defined structure as stochastic analysis techniques equally do. In this article, we look into the structure inference problem for a model described by a system of Ordinary Differential Equations and provide conditions for the uniqueness of its solution. We describe a method to extract a structured reaction network model, represented as a bipartite multigraph, for example, a continuous Petri net (CPN, from a system of Ordinary Differential Equations (ODEs. A CPN uniquely defines an ODE, and each ODE can be transformed into a CPN. However, it is not obvious under which conditions the transformation of an ODE into a CPN is unique, that is, when a given ODE defines exactly one CPN. We provide biochemically relevant sufficient conditions under which the derived structure is unique and counterexamples showing the necessity of each condition. Our method is implemented and available; we illustrate it on some signal transduction models from the BioModels database. A prototype implementation of the method is made available to modellers at http://contraintes.inria.fr/~soliman/ode2pn.html, and the data mentioned in the "Results" section at http://contraintes.inria.fr/~soliman/ode2pn_data/. Our results yield a new recommendation for the import/export feature of tools supporting the SBML exchange format.

  20. Thermal and impact history of the H chondrite parent asteroid during metamorphism: Constraints from metallic Fe-Ni

    Science.gov (United States)

    Scott, Edward R. D.; Krot, Tatiana V.; Goldstein, Joseph I.; Wakita, Shigeru

    2014-07-01

    We have studied cloudy taenite, metallographic cooling rates, and shock effects in 30 H3-6 chondrites to elucidate the thermal and early impact history of the H chondrite parent body. We focused on H chondrites with old Ar-Ar ages (>4.4 Gyr) and unshocked and mildly shocked H chondrites, as strongly shocked chondrites with such old ages are very rare. Cooling rates for most H chondrites at 500 °C are 10-50 °C/Myr and do not decrease systematically with increasing petrologic type as predicted by the onion-shell model in which types 3-5 are arranged in concentric layers around a type 6 core. Some type 4 chondrites cooled slower than some type 6 chondrites and type 3 chondrites did not cool faster than other types, contrary to the onion-shell model. Cloudy taenite particle sizes, which range from 40 to 120 nm, are inversely correlated with metallographic cooling rates and show that the latter were not compromised by shock heating. The three H4 chondrites that were used to develop the onion-shell model, Ste. Marguerite, Beaver Creek, and Forest Vale, cooled through 500 °C at ⩾5000 °C/Myr. Our thermal modeling shows that these rates are 50× higher than could be achieved in a body that was heated by 26Al and cooled without disturbance by impact. Published Ar-Ar ages do not decrease systematically with increasing petrologic type but do correlate inversely with cloudy taenite particle size suggesting that impact mixing decreased during metamorphism. Metal and silicate compositions in regolith breccias show that impacts mixed material after metamorphism without causing significant heating. Impacts during metamorphism created Portales Valley and two other H6 chondrites with large metallic veins, excavated the fast-cooled H4 chondrites around 3-4 Myr after accretion, and mixed petrologic types. Metallographic data do not require catastrophic disruption by impact during cooling.

  1. Nature of volatile depletion and genetic relationships in enstatite chondrites and aubrites inferred from Zn isotopes

    Science.gov (United States)

    Moynier, Frédéric; Paniello, Randal C.; Gounelle, Matthieu; Albarède, Francis; Beck, Pierre; Podosek, Frank; Zanda, Brigitte

    2011-01-01

    Enstatite meteorites include the undifferentiated enstatite chondrites and the differentiated enstatite achondrites (aubrites). They are the most reduced group of all meteorites. The oxygen isotope compositions of both enstatite chondrites and aubrites plot along the terrestrial mass fractionation line, which suggests some genetic links between these meteorites and the Earth as well. For this study, we measured the Zn isotopic composition of 25 samples from the following groups: aubrites (main group and Shallowater), EL chondrites, EH chondrites and Happy Canyon (impact-melt breccia). We also analyzed the Zn isotopic composition and elemental abundance in separated phases (metal, silicates, and sulfides) of the EH4, EL3, and EL6 chondrites. The different groups of meteorites are isotopically distinct and give the following values (‰): aubrite main group (-7.08 Luck et al., 2005; Herzog et al., 2009). EH and EL3 chondrites have the same Zn isotopic composition as the Earth, which is another example of the isotopic similarity between Earth and enstatite chondrites. The Zn isotopic composition and abundance strongly support that the origin of the volatile element depletion between EL3 and EL6 chondrites is due to volatilization, probably during thermal metamorphism. Aubrites show strong elemental depletion in Zn compared to both EH and EL chondrites and they are enriched in light isotopes (δ 66Zn down to -7.04‰). This is the opposite of what would be expected if Zn elemental depletion was due to evaporation, assuming the aubrites started with an enstatite chondrite-like Zn isotopic composition. Evaporation is therefore not responsible for volatile loss from aubrites. On Earth, Zn isotopes fractionate very little during igneous processes, while differentiated meteorites show only minimal Zn isotopic variability. It is therefore very unlikely that igneous processes can account for the large isotopic fractionation of Zn in aubrites. Condensation of an isotopically

  2. Chondritic Models of 4 Vesta: Comparison of Data from the Dawn Mission with Predicted Internal Structure and Surface Composition/Mineralogy

    Science.gov (United States)

    Toplis, M. J.; Mizzon, H.; Forni, O.; Monnereau, M.; Barrat, J-A.; Prettyman, T. H.; McSween, H. Y.; McCoy, T. J.; Mittlefehldt, D. W.; De Sanctis, M. C.; hide

    2012-01-01

    While the HEDs provide an extremely useful basis for interpreting data from the Dawn mission, there is no guarantee that they provide a complete vision of all possible crustal (and possibly mantle) lithologies that are exposed at the surface of Vesta. With this in mind, an alternative approach is to identify plausible bulk compositions and use mass-balance and geochemical modelling to predict possible internal structures and crust/mantle compositions and mineralogies. While such models must be consistent with known HED samples, this approach has the potential to extend predictions to thermodynamically plausible rock types that are not necessarily present in the HED collection. Nine chondritic bulk compositions are considered (CI, CV, CO, CM, H, L, LL, EH, EL). For each, relative proportions and densities of the core, mantle, and crust are quantified. This calculation is complicated by the fact that iron may occur in metallic form (in the core) and/or in oxidized form (in the mantle and crust). However, considering that the basaltic crust has the composition of Juvinas and assuming that this crust is in thermodynamic equilibrium with the residual mantle, it is possible to calculate a single solution to this problem for a given bulk composition. Of the nine bulk compositions tested, solutions corresponding to CI and LL groups predicted a negative metal fraction and were not considered further. Solutions for enstatite chondrites imply significant oxidation relative to the starting materials and these solutions too are considered unlikely. For the remaining bulk compositions, the relative proportion of crust to bulk silicate is typically in the range 15 to 20% corresponding to crustal thicknesses of 15 to 20 km for a porosity-free Vesta-sized body. The mantle is predicted to be largely dominated by olivine (greater than 85%) for carbonaceous chondrites, but to be a roughly equal mixture of olivine and pyroxene for ordinary chondrite precursors. All bulk compositions

  3. Porting Ordinary Applications to Blue Gene/Q Supercomputers

    Energy Technology Data Exchange (ETDEWEB)

    Maheshwari, Ketan C.; Wozniak, Justin M.; Armstrong, Timothy; Katz, Daniel S.; Binkowski, T. Andrew; Zhong, Xiaoliang; Heinonen, Olle; Karpeyev, Dmitry; Wilde, Michael

    2015-08-31

    Efficiently porting ordinary applications to Blue Gene/Q supercomputers is a significant challenge. Codes are often originally developed without considering advanced architectures and related tool chains. Science needs frequently lead users to want to run large numbers of relatively small jobs (often called many-task computing, an ensemble, or a workflow), which can conflict with supercomputer configurations. In this paper, we discuss techniques developed to execute ordinary applications over leadership class supercomputers. We use the high-performance Swift parallel scripting framework and build two workflow execution techniques-sub-jobs and main-wrap. The sub-jobs technique, built on top of the IBM Blue Gene/Q resource manager Cobalt's sub-block jobs, lets users submit multiple, independent, repeated smaller jobs within a single larger resource block. The main-wrap technique is a scheme that enables C/C++ programs to be defined as functions that are wrapped by a high-performance Swift wrapper and that are invoked as a Swift script. We discuss the needs, benefits, technicalities, and current limitations of these techniques. We further discuss the real-world science enabled by these techniques and the results obtained.

  4. A variational approach to parameter estimation in ordinary differential equations.

    Science.gov (United States)

    Kaschek, Daniel; Timmer, Jens

    2012-08-14

    Ordinary differential equations are widely-used in the field of systems biology and chemical engineering to model chemical reaction networks. Numerous techniques have been developed to estimate parameters like rate constants, initial conditions or steady state concentrations from time-resolved data. In contrast to this countable set of parameters, the estimation of entire courses of network components corresponds to an innumerable set of parameters. The approach presented in this work is able to deal with course estimation for extrinsic system inputs or intrinsic reactants, both not being constrained by the reaction network itself. Our method is based on variational calculus which is carried out analytically to derive an augmented system of differential equations including the unconstrained components as ordinary state variables. Finally, conventional parameter estimation is applied to the augmented system resulting in a combined estimation of courses and parameters. The combined estimation approach takes the uncertainty in input courses correctly into account. This leads to precise parameter estimates and correct confidence intervals. In particular this implies that small motifs of large reaction networks can be analysed independently of the rest. By the use of variational methods, elements from control theory and statistics are combined allowing for future transfer of methods between the two fields.

  5. Porosity of an Anhydrous Chondritic Interplanetary Dust Particle

    Science.gov (United States)

    Strait, M. M.; Thomas, K. L.; McKay, D. S.

    1995-09-01

    Determination of the density and porosity of Interplanetary Dust Particles (IDPs) is important in the dynamics of collisional and orbital evolution of small-sized particles. These measurements are also useful to suggest possible sources for IDPs based on comparisons with known extraterrestrial materials (e.g., chondrites). Previous work on IDPs shows a wide range of densities from very low (0.08 g/cm3 [1]) through low (0.3 g/cm3 [2]) to high (6.2 g/cm3 [3]), with an average density at 2.0 g/cm3 for 150 particles [2]. In another study, IDPs fall into two distinct density groups with mean values of 0.6 g/cm3 and 1.9g/cm3 [3]. In general, chondritic IDPs with lower density values most likely have appreciable porosity, suggesting they are primitive, uncompacted particles. It is believed that porosities greater than 70% are rare [2]. Sample In this study, porosity measurements were determined for one IDP, Clu17. This chondritic particle is a fragment of a large-sized IDP (L2008#5) known as a cluster particle. The cluster is composed of 53 fragments >5 micrometers in diameter; a detailed description of the cluster is given in [4]. IDP Clu17 has ~12 wt.% C and contains chondritic abundances (within 2xCI) for major elements. This fragment is dominated by fine-grained aggregates, also known as GEMS (glass with embedded metal and sulfide [5]), and contains some olivine, pyroxene, Fe-Ni sulfides, and carbonaceous material. Methods IDP Clu17 was analyzed for light elements quantitatively analysis using scanning electron microscopy and thin-window energy dispersive spectrometry [details of technique in 4]. Following the initial bulk chemical analysis, the particle was embedded in epoxy, thin sectioned using an ultramicrotome, and examined with a JEOL 2000 FX transmission electron microscope. Many of the sections were not complete; individual grains in some sections are lost during microtoming. Photos from nine of the best sections were digitized by scanning at 1200 dpi. The

  6. Phase relations of a carbonaceous chondrite at lower mantle conditions

    Science.gov (United States)

    Asahara, Yuki; Kubo, Tomoaki; Kondo, Tadashi

    2004-06-01

    The phase relations of Allende meteorite, which belongs to the CV carbonaceous chondrites, were investigated at 22-25 GPa and 1600-2300 °C. With increasing pressure, the liquidus phase changes from garnet to Mg-perovskite at about 24.5 GPa. Magnesiowüstite crystallizes as the second phase throughout the investigated pressure range, and the solidus curve coincides with the appearance of ringwoodite below 23 GPa, Mg-perovskite at 23-24 GPa and Ca-perovskite above 24 GPa. Immiscible silicate and metallic liquid phases are present in the entire melting range, and a single metallic liquid persists below the solidus down to at least 1600 °C. The Kd(Fe/Mg) crystal/silicate liq. is well below unity for magnesiowüstite (0.7-0.8), garnet (0.35-0.39) and Mg-perovskite (0.34). Ni and S are strongly partitioned into the metallic liquid, and the Ni and Fe partition coefficients between metallic liquid and coexisting minerals are relatively constant with variations in pressure or temperature. An important factor controlling Dmetal liq./crystal of Fe and Ni is the oxygen fugacity. Our results provide further constraints on models for early Earth differentiation and core formation.

  7. Collisional erosion and the non-chondritic composition of the terrestrial planets.

    Science.gov (United States)

    O'Neill, Hugh St C; Palme, Herbert

    2008-11-28

    The compositional variations among the chondrites inform us about cosmochemical fractionation processes during condensation and aggregation of solid matter from the solar nebula. These fractionations include: (i) variable Mg-Si-RLE ratios (RLE: refractory lithophile element), (ii) depletions in elements more volatile than Mg, (iii) a cosmochemical metal-silicate fractionation, and (iv) variations in oxidation state. Moon- to Mars-sized planetary bodies, formed by rapid accretion of chondrite-like planetesimals in local feeding zones within 106 years, may exhibit some of these chemical variations. However, the next stage of planetary accretion is the growth of the terrestrial planets from approximately 102 embryos sourced across wide heliocentric distances, involving energetic collisions, in which material may be lost from a growing planet as well as gained. While this may result in averaging out of the 'chondritic' fractionations, it introduces two non-chondritic chemical fractionation processes: post-nebular volatilization and preferential collisional erosion. In the latter, geochemically enriched crust formed previously is preferentially lost. That post-nebular volatilization was widespread is demonstrated by the non-chondritic Mn/Na ratio in all the small, differentiated, rocky bodies for which we have basaltic samples, including the Moon and Mars. The bulk silicate Earth (BSE) has chondritic Mn/Na, but shows several other compositional features in its pattern of depletion of volatile elements suggestive of non-chondritic fractionation. The whole-Earth Fe/Mg ratio is 2.1+/-0.1, significantly greater than the solar ratio of 1.9+/-0.1, implying net collisional erosion of approximately 10 per cent silicate relative to metal during the Earth's accretion. If this collisional erosion preferentially removed differentiated crust, the assumption of chondritic ratios among all RLEs in the BSE would not be valid, with the BSE depleted in elements according to their

  8. High Precision Oxygen Three Isotope Analysis of Wild-2 Particles and Anhydrous Chondritic Interplanetary Dust Particles

    Science.gov (United States)

    Nakashima, D.; Ushikubo, T.; Zolensky, Michael E.; Weisberg, M. K.; Joswiak, D. J.; Brownlee, D. E.; Matrajt, G.; Kita, N. T.

    2011-01-01

    One of the most important discoveries from comet Wild-2 samples was observation of crystalline silicate particles that resemble chondrules and CAIs in carbonaceous chondrites. 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 carbonaceous chondrites, 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 carbonaceous chondrite 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 (isotope analyses of Wild-2 particles and anhydrous chondritic IDPs, and discuss the relationship between the cometary dust and carbonaceous chondrite chondrules.

  9. Ordinary multiplication of distributions. Application to control of economic processes

    Science.gov (United States)

    Kim, A. V.; Kormyshev, V. M.; Serova, N. B.; Fitina, L. N.; Kozhakhmetov, A. B.

    2017-11-01

    There exist many physical and economic models, which cannot be described in terms of usual functions. Such problems require application of the theory of distributions (generalized functions) (P. Antosik, J. Mikusinski, R. Sikorski, 1973; J. F. Colombeau, 1984; A.V. Kim, 2015, 1988; S.L. Sobolev, 1950; L Schwartz, 1950-1951). One of the first and the most important problems of the distribution theory consist in impossibility of defining a multiplication of distribution. The problem is so important that still is in the focus of researchers, because of various applications to nonlinear singular models. In the paper, an ordinary multiplication of generalized functions (distributions) is proposed. The obtained results are applied in a problem of control of economic processes.

  10. Algorithmic Verification of Linearizability for Ordinary Differential Equations

    KAUST Repository

    Lyakhov, Dmitry A.

    2017-07-19

    For a nonlinear ordinary differential equation solved with respect to the highest order derivative and rational in the other derivatives and in the independent variable, we devise two algorithms to check if the equation can be reduced to a linear one by a point transformation of the dependent and independent variables. The first algorithm is based on a construction of the Lie point symmetry algebra and on the computation of its derived algebra. The second algorithm exploits the differential Thomas decomposition and allows not only to test the linearizability, but also to generate a system of nonlinear partial differential equations that determines the point transformation and the coefficients of the linearized equation. The implementation of both algorithms is discussed and their application is illustrated using several examples.

  11. Searching fundamental information in ordinary differential equations. Nondimensionalization technique.

    Science.gov (United States)

    Sánchez Pérez, J F; Conesa, M; Alhama, I; Alhama, F; Cánovas, M

    2017-01-01

    Classical dimensional analysis and nondimensionalization are assumed to be two similar approaches in the search for dimensionless groups. Both techniques, simplify the study of many problems. The first approach does not need to know the mathematical model, being sufficient a deep understanding of the physical phenomenon involved, while the second one begins with the governing equations and reduces them to their dimensionless form by simple mathematical manipulations. In this work, a formal protocol is proposed for applying the nondimensionalization process to ordinary differential equations, linear or not, leading to dimensionless normalized equations from which the resulting dimensionless groups have two inherent properties: In one hand, they are physically interpreted as balances between counteracting quantities in the problem, and on the other hand, they are of the order of magnitude unity. The solutions provided by nondimensionalization are more precise in every case than those from dimensional analysis, as it is illustrated by the applications studied in this work.

  12. Phonon hydrodynamics for nanoscale heat transport at ordinary temperatures

    Science.gov (United States)

    Guo, Yangyu; Wang, Moran

    2018-01-01

    The classical Fourier's law fails in extremely small and ultrafast heat conduction even at ordinary temperatures due to strong thermodynamic nonequilibrium effects. In this work, a macroscopic phonon hydrodynamic equation beyond Fourier's law with a relaxation term and nonlocal terms is derived through a perturbation expansion to the phonon Boltzmann equation around a four-moment nonequilibrium solution. The temperature jump and heat flux tangential retardant boundary conditions are developed based on the Maxwell model of the phonon-boundary interaction. Extensive steady-state and transient nanoscale heat transport cases are modeled by the phonon hydrodynamic model, which produces quantitative predictions in good agreement with available phonon Boltzmann equation solutions and experimental results. The phonon hydrodynamic model provides a simple and elegant mathematical description of non-Fourier heat conduction with a clear and intuitive physical picture. The present work will promote deeper understanding and macroscopic modeling of heat transport in extreme states.

  13. Nonlinear ordinary differential equations analytical approximation and numerical methods

    CERN Document Server

    Hermann, Martin

    2016-01-01

    The book discusses the solutions to nonlinear ordinary differential equations (ODEs) using analytical and numerical approximation methods. Recently, analytical approximation methods have been largely used in solving linear and nonlinear lower-order ODEs. It also discusses using these methods to solve some strong nonlinear ODEs. There are two chapters devoted to solving nonlinear ODEs using numerical methods, as in practice high-dimensional systems of nonlinear ODEs that cannot be solved by analytical approximate methods are common. Moreover, it studies analytical and numerical techniques for the treatment of parameter-depending ODEs. The book explains various methods for solving nonlinear-oscillator and structural-system problems, including the energy balance method, harmonic balance method, amplitude frequency formulation, variational iteration method, homotopy perturbation method, iteration perturbation method, homotopy analysis method, simple and multiple shooting method, and the nonlinear stabilized march...

  14. Random ordinary differential equations and their numerical solution

    CERN Document Server

    Han, Xiaoying

    2017-01-01

    This book is intended to make recent results on the derivation of higher order numerical schemes for random ordinary differential equations (RODEs) available to a broader readership, and to familiarize readers with RODEs themselves as well as the closely associated theory of random dynamical systems. In addition, it demonstrates how RODEs are being used in the biological sciences, where non-Gaussian and bounded noise are often more realistic than the Gaussian white noise in stochastic differential equations (SODEs).   RODEs are used in many important applications and play a fundamental role in the theory of random dynamical systems.  They can be analyzed pathwise with deterministic calculus, but require further treatment beyond that of classical ODE theory due to the lack of smoothness in their time variable. Although classical numerical schemes for ODEs can be used pathwise for RODEs, they rarely attain their traditional order since the solutions of RODEs do not have sufficient smoothness to have Taylor ...

  15. Quasilinear saturation of the aperiodic ordinary mode streaming instability

    Energy Technology Data Exchange (ETDEWEB)

    Stockem Novo, A., E-mail: anne@tp4.rub.de; Schlickeiser, R. [Institut für Theoretische Physik, Lehrstuhl IV: Weltraum-und Astrophysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Yoon, P. H. [Institute for Physical Science & Technology, University of Maryland, College Park, Maryland 20742 (United States); School of Space Research, Kyung Hee University, Yongin-Si, Gyeonggi-Do 446-701 (Korea, Republic of); Lazar, M. [Institut für Theoretische Physik, Lehrstuhl IV: Weltraum-und Astrophysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Centre for Mathematical Plasma Astrophysics, Celestijnenlaan 200B, 3001 Leuven (Belgium); Poedts, S. [Centre for Mathematical Plasma Astrophysics, Celestijnenlaan 200B, 3001 Leuven (Belgium); Seough, J. [Faculty of Human Development, University of Toyama, 3190, Gofuku, Toyama City, Toyama 930-8555 (Japan); International Research Fellow of the Japan Society for the Promotion of Science, Tokyo (Japan)

    2015-09-15

    In collisionless plasmas, only kinetic instabilities and fluctuations are effective in reducing the free energy and scatter plasma particles, preventing an increase of their anisotropy. Solar energetic outflows into the interplanetary plasma give rise to important thermal anisotropies and counterstreaming motions of plasma shells, and the resulting instabilities are expected to regulate the expansion of the solar wind. The present paper combines quasilinear theory and kinetic particle-in-cell simulations in order to study the weakly nonlinear saturation of the ordinary mode in hot counter-streaming plasmas with a temperature anisotropy as a follow-up of the paper by Seough et al. [Phys. Plasmas 22, 082122 (2015)]. This instability provides a plausible mechanism for the origin of dominating, two-dimensional spectrum of transverse magnetic fluctuations observed in the solar wind. Stimulated by the differential motion of electron counterstreams the O mode instability may convert their free large-scale energy by nonlinear collisionless dissipation on plasma particles.

  16. Soliton-like solutions to the ordinary Schroedinger equation

    Energy Technology Data Exchange (ETDEWEB)

    Zamboni-Rached, Michel [Universidade Estadual de Campinas (DMO/FEEC/UNICAMP), Campinas, SP (Brazil). Fac. de Engenharia Eletrica e de Computacao. Dept. de Microondas e Optica; Recami, Erasmo, E-mail: recami@mi.infn.i [Universita Statale di Bergamo, Bergamo (Italy). Facolta di Ingegneria

    2011-07-01

    In recent times it has been paid attention to the fact that (linear) wave equations admit of soliton-like solutions, known as Localized Waves or Non-diffracting Waves, which propagate without distortion in one direction. Such Localized Solutions (existing also for K-G or Dirac equations) are a priori suitable, more than Gaussian's, for describing elementary particle motion. In this paper we show that, mutatis mutandis, Localized Solutions exist even for the ordinary Schroedinger equation within standard Quantum Mechanics; and we obtain both approximate and exact solutions, also setting forth for them particular examples. In the ideal case such solutions bear infinite energy, as well as plane or spherical waves: we show therefore how to obtain nite-energy solutions. At last, we briefly consider solutions for a particle moving in the presence of a potential. (author)

  17. Differential equations a dynamical systems approach ordinary differential equations

    CERN Document Server

    Hubbard, John H

    1991-01-01

    This is a corrected third printing of the first part of the text Differential Equations: A Dynamical Systems Approach written by John Hubbard and Beverly West. The authors' main emphasis in this book is on ordinary differential equations. The book is most appropriate for upper level undergraduate and graduate students in the fields of mathematics, engineering, and applied mathematics, as well as the life sciences, physics and economics. Traditional courses on differential equations focus on techniques leading to solutions. Yet most differential equations do not admit solutions which can be written in elementary terms. The authors have taken the view that a differential equations defines functions; the object of the theory is to understand the behavior of these functions. The tools the authors use include qualitative and numerical methods besides the traditional analytic methods. The companion software, MacMath, is designed to bring these notions to life.

  18. Tracking, aiming, and hitting the UAV with ordinary assault rifle

    Science.gov (United States)

    Racek, František; Baláž, Teodor; Krejčí, Jaroslav; Procházka, Stanislav; Macko, Martin

    2017-10-01

    The usage small-unmanned aerial vehicles (UAVs) is significantly increasing nowadays. They are being used as a carrier of military spy and reconnaissance devices (taking photos, live video streaming and so on), or as a carrier of potentially dangerous cargo (intended for destruction and killing). Both ways of utilizing the UAV cause the necessity to disable it. From the military point of view, to disable the UAV means to bring it down by a weapon of an ordinary soldier that is the assault rifle. This task can be challenging for the soldier because he needs visually detect and identify the target, track the target visually and aim on the target. The final success of the soldier's mission depends not only on the said visual tasks, but also on the properties of the weapon and ammunition. The paper deals with possible methods of prediction of probability of hitting the UAV targets.

  19. Simulation and quasilinear theory of aperiodic ordinary mode instability

    Energy Technology Data Exchange (ETDEWEB)

    Seough, Jungjoon [Faculty of Human Development, University of Toyama, 3190, Gofuku, Toyama City, Toyama 930-8555 (Japan); International Research Fellow of the Japan Society for the Promotion of Science, Tokyo (Japan); Yoon, Peter H. [Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States); School of Space Research, Kyung Hee University, Yongin-Si, Gyeonggi-Do 446-701 (Korea, Republic of); Hwang, Junga [Korea Astronomy and Space Science Institute, Daejeon (Korea, Republic of); Department of Astronomy and Space Science, University of Science and Technology, Daejeon (Korea, Republic of); Nariyuki, Yasuhiro [Faculty of Human Development, University of Toyama, 3190, Gofuku, Toyama City, Toyama 930-8555 (Japan)

    2015-08-15

    The purely growing ordinary (O) mode instability driven by excessive parallel temperature anisotropy for high-beta plasmas was first discovered in the 1970s. This instability receives renewed attention because it may be applicable to the solar wind plasma. The electrons in the solar wind feature temperature anisotropies whose upper values are apparently limited by plasma instabilities. The O-mode instability may be important in this regard. Previous studies of O mode instability have been based on linear theory, but the actual solar wind electrons may be in saturated state. The present paper investigates the nonlinear saturation behavior of the O mode instability by means of one-dimensional particle-in-cell simulation and quasilinear theory. It is shown that the quasilinear method accurately reproduces the simulation results.

  20. Matrix mineralogy of the Lance CO3 carbonaceous chondrite - A transmission electron microscope study

    Science.gov (United States)

    Keller, Lindsay P.; Buseck, Peter R.

    1990-01-01

    Results are presented on electron microprobe analyses of three CO chondrites, all of which are falls: Lance, Kainsaz, and Warrenton. The TEM mineralogy results of Lance chondrite show that Fe-rich matrix olivines have been altered to Fe-bearing serpentine and Fe(3+) oxide; matrix metal was also altered to produce Fe(3+) oxides, leaving the residual metal enriched in Ni. Olivine grains in Lance's matrix contain channels along their 100-line and 001-line directions; the formation and convergence of such channels resulted in a grain-size reduction of the olivine. A study of Kainsaz and Warrenton showed that these meteorites do not contain phyllosilicates in their matrices, although both contain Fe(3+) oxide between olivine grains. It is suggested that, prior to its alteration, Lance probably resembled Kainsaz, an unaltered CO3 chondrite.

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

    Science.gov (United States)

    Jones, Rhian H.; Rubie, David C.

    1991-01-01

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

  2. Assessing the Formation of Ungrouped Achondrite Northwest Africa 8186: Residue, Crystallization Product, or Recrystallized Chondrite?

    Science.gov (United States)

    Srinivasan, P.; McCubbin, F. M.; Agee, C. B.

    2016-01-01

    The recent discoveries of primitive achondrites, metachondrites, and type 7 chondrites challenge the long held idea that all chondrites and achondrites form on separate parent bodies. These meteorites have experienced metamorphic temperatures above petrologic type 6 and have partially melted to various degrees. However, because of their isotopic and compositional similarities to both undifferentiated and differentiated groups, the provenance of these 'type 6+' meteorites remains largely unknown. CK and CV chondrites have recently been linked to a few achondrites due to their strong compositional, mineralogical, and isotopic similarities], suggesting a common origin between these meteorites. Although CVs have generally undergone low degrees of alteration near petrologic type 3, CKs have experienced a wide range of thermal alteration from petrologic type 3 to 6. Thermal evolution models on early accreting bodies predict that an early forming body can partially differentiate due to radiogenic heating, and, as a result, form radial layers of material increasing in thermal grade (types 3 to 6+) from the unmelted chondritic surface towards the differentiated core.Northwest Africa (NWA) 8186 is an ungrouped achondrite that provides compelling evidence for higher degrees of thermal processing and/or melting and differentiation on some CK/CV parent bodies. NWA 8186 plots on the CCAM line on a 3-oxygen isotope diagram directly with CK and CV chondrites and also plots with the CKs in regards to Cr isotopes. This meteorite is dominated by Nickel(II)Oxygen-rich olivine (less than 80%), lacks iron metal, and contains four oxide phases, indicating a high fOxygen (above FMQ) similar to the CKs. Additionally, NWA 8186 does not contain chondrules. We have further investigated the origins of NWA 8186 by examining and comparing the bulk composition of this CK-like achondrite with CK and CV chondrites, allowing us to assess the various scenarios in which NWA 8186 may have formed from

  3. Fractional crystallization of olivine melt inclusion in shock-induced chondritic melt vein

    Science.gov (United States)

    Miyahara, M.; El Goresy, A.; Ohtani, E.; Kimura, M.; Ozawa, S.; Nagase, T.; Nishijima, M.

    2009-12-01

    The formation of ringwoodite, wadsleyite and majorite from their parental low-pressure polymorphs in melt veins in chondritic meteorites is usually interpreted to be the result of shock-induced solid-state phase transformation. Formation and survival of individual mineral melt enclaves in the chondritic high-pressure melt was not considered a viable possibility. We report evidence for melting of individual large olivine fragments entrained in melt veins, their survival as melt enclaves in the chondritic melts and their subsequent fractional crystallization at high-pressures and temperatures. The fractionally crystallized olivine melt enclaves appear to be ubiquitous in chondrites. In contrast, Ca-poor pyroxene fragments in the same veins and Ca-poor pyroxene in chondrules entrained do not show any sign of melting. Texture and compositions of olivine fragments are indicative of fractional crystallization from individual olivine melts alone. Fragments of original unzoned olivine (Fa 24-26) melted, and melts subsequently fractionally crystallized to Mg-rich wadsleyite (Fa 6-10) and Mg-poor ringwoodite (Fa 28-33) with a compositional gap of ≤26 mol% fayalite. In contrast, compositions of ringwoodite and wadsleyite that emerged from solid-sate phase transformations are identical to that of parental olivine thus erasing any source of enigma. The olivine monomineralic melts barely show any signs of mixing with the chondritic liquid prior to or during their individual fractional crystallization. Our findings demonstrate that the formation of high-pressure minerals during shock events in asteroids also results from melting and fractional crystallization from some individual mineral melts that barely mixed with the chondritic melt host, a mechanism previously not recognized or accepted.

  4. The Oxygen Isotopic Composition of MIL 090001: A CR2 Chondrite with Abundant Refractory Inclusions

    Science.gov (United States)

    Keller, Lindsay P.; McKeegan, K. D.; Sharp, Z. D.

    2012-01-01

    MIL 090001 is a large (>6 kg) carbonaceous chondrite 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 chondrite.

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

    DEFF Research Database (Denmark)

    van Kooten, Elishevah M. M. E.; Wielandt, Daniel Kim Peel; Schiller, Martin

    2016-01-01

    -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....

  6. A Case for Nebula Scale Mixing Between Non-Carbonaceous and Carbonaceous Chondrite Reservoirs: Testing the Grand Tack Model with Chromium Isotopic Composition of Almahata Sitta Stone 91A

    Science.gov (United States)

    Sanborn, M. E.; Yin, Q.-Z.; Goodrich, C. A.; Zolensky, M.; Fioretti, A. M.

    2017-01-01

    There is an increasing number of Cr-O-Ti isotope studies that show solar system materials are divided into two main populations, one carbonaceous chondrite (CC)-like and the other is non-carbonaceous (NC)-like, with minimal mixing attributed to a gap opened in the protoplanetary disk due to Jupiter's formation. The Grand Tack model suggests there should be large-scale mixing between S- and C-type asteroids, an idea supported by our recent work on chondrule (Delta)17O-e54Cr isotope systematics. The Almahata Sitta (AhS) meteorite provides a unique opportunity to test the Grand Tack model. The meteorite fell to Earth in October 2008 and has been linked to the asteroid 2008 TC3 which was discovered just prior to the fall of the AhS stones. The AhS meteorite is composed of up to 700 individual pieces with approx.140 of those pieces having some geochemical and/or petrologic studies. Almahata Sitta is an anomalous polymict ureilite with other meteorite components, including enstatite, ordinary, and carbonaceous chondrites with an approximate abundance of 70% ureilites and 30% chondrites. This observation has lead to the suggestion that TC3 2008 was a loosely aggregated rubble pile-like asteroid with the non-ureilite sample clasts within the rubble-pile. Due to the loosely-aggregated nature of AhS, the object disintegrated during atmospheric entry resulting in the weakly held clasts falling predominantly as individual stones in the AhS collection area. However, recent work has identified one sample of AhS, sample 91A, which may represent two different lithologies coexisting within a single stone. The predominate lithology type in 91A appears to be that of a C2 chondrite based on mineralogy but also contains olivine, pyroxene, and albite that have ureilite-like compositions. Previous Cr isotope investigations into AhS stones are sparse and what data is available show nearly uniform isotopic composition similar to that of typical ureilites with negative e54Cr values.

  7. Spectacular fall of the Kendrapara H5 chondrite

    Science.gov (United States)

    Dhingra, D.; Bhandari, N.; Shukla, P. N.; Murty, S. V. S.; Mahajan, R. R.; Ballabh, G. M.; Lashkari, G.; Shukla, A. D.; Parthasarathy, G.

    2004-08-01

    An extremely bright fireball was seen for over 250 km near the eastern coast of India in the evening sky on September 27, 2003. In a rare observation, the fireball was seen by two airline pilots, providing direction of the trail with reasonable accuracy, consistent with ground-based observations. A few fragments of the meteorite were subsequently recovered along the end of the trail in different parts of Kendrapara district (20°30' N; 86°26' E) of Orissa. Based on petrography and chemical composition, the meteorite is classified as H5 chondrite. The cosmogenic radionuclides 54Mn, 22Na, 60Co, and 26Al and tracks have been studied in this stony meteorite. Two of the fragments show an unusually high activity of 60Co (~160 dpm/kg) indicating a meteoroid radius of 50-150 cm. Assuming that less than 10% (by weight) of the fragments could be recovered because of difficult terrain, an atmospheric mass ablation of >95% is estimated. Based on the observations of the trail and the estimated mass ablation, orbital parameters of the meteoroid have been calculated. The aphelion is found to lie in the asteroidal belt (1.8-2.4 AU), but the inclination of the orbit is large (22°-26°) with respect to the ecliptic. Noble gases have been analysed in two samples of this meteorite. He and Ne are dominantly cosmogenic. Using production rates based on the sample depth derived from 60Co content, 21Ne-based exposure age of 4.50 ± 0.45 Ma is derived for Kendrapara. One of the samples, known to be more deeply shielded based on high 60Co activity, shows the presence of 80Kr, 82Kr, and 128Xe produced by (n, g) reaction on 79Br, 81Br, and 127I, respectively. The (80Kr/82Kr)n ratio of 3.5 ± 0.9 is consistent with neutrons being mostly thermal. Trapped 84Kr and 132Xe are in the expected range for metamorphic grade H5.

  8. Ordinary Mathematical Models in Calculating the Aviation GTE Parameters

    Directory of Open Access Journals (Sweden)

    E. A. Khoreva

    2017-01-01

    Full Text Available The paper presents the analytical review results of the ordinary mathematical models of the operating process used to study aviation GTE parameters and characteristics at all stages of its creation and operation. Considers the mathematical models of the zero and the first level, which are mostly used when solving typical problems in calculating parameters and characteristics of engines.Presents a number of practical problems arising in designing aviation GTE for various applications.The application of mathematical models of the zero-level engine can be quite appropriate when the engine is considered as a component in the aircraft system to estimate its calculated individual flight performance or when modeling the flight cycle of the aircrafts of different purpose.The paper demonstrates that introduction of correction functions into the first-level mathematical models in solving typical problems (influence of the Reynolds number, characteristics deterioration of the units during the overhaul period of engine, as well as influence of the flow inhomogeneity at the inlet because of manufacturing tolerance, etc. enables providing a sufficient engineering estimate accuracy to reflect a realistic operating process in the engine and its elements.

  9. ORDINARY PERSON IN MEDIA: PUBLIC INTEREST AND PROFESSIONAL EXPERIENCE

    Directory of Open Access Journals (Sweden)

    Sergey G. Korkonosenko

    2016-04-01

    Full Text Available This paper is based on the results of the research project “Media Discourses on Material and Ethnic Gaps. A comparative study in St Petersburg and Stockholm” financed by the Foundation for Baltic and East European Studies (Sweden. One of the main sections of the project was focused on ordinary persons’ portrayal in comparison with images of so-called celebrities in the regional media. Russian and Swedish scholars used a set of methods such as content analysis of newspapers and TV, expert in-depth interviews, and focus groups (2013, Spring - Summer. In fact, common men appeared rarely in TV excerpts and newspaper articles, especially in Russia. At the same time non-commons were shown in the majority of Russian TV and print media items while Swedish media give the opposite proportions. To explain gaps between Russian and Swedish findings one needs to take into account different social and mental traditions in these countries. The difference has been revealed within expert interviews and focus groups.

  10. The Sound of a Small Whisper: Ordinary Religious Experience

    Directory of Open Access Journals (Sweden)

    Kugelmann Robert

    2017-01-01

    Full Text Available An ordinary religious experience does not entail an overwhelming sense of the Divine; it is not a “numinous” experience. It is instead easily ignored. In a phenomenological psychological inquiry into such a religious experience, both the noema, the “what” experienced, and the noesis, the mode of givenness of the experience, manifested themselves in distinctive ways. The paper examines a simple experience of having been guided in making a decision. The guidance was recognized only at the moment of realization. The realization revealed the decision to have been part of a larger drama that transcended the immediate experience. The “world” of this moment of realization included sensing that the sky above-as an “elemental”-was a dome, with allusions to the Noah story. Even at the time, this perception was not experienced as literal, but as symbolic. The social, historical, and theological contexts for the possibility of this experience receive attention. Theological as well as psychological reflection indicate such an experience continues to happen, in memory and thought, and even in action, long after the initial moment. Essential to the meaning of the experience is an admonition to transcend egocentricity.

  11. Standing Concertation Committee - Ordinary Meeting on 15 January 2005

    CERN Document Server

    2005-01-01

    This meeting was devoted to the main topics summarised below. Follow-up from the meetings of the Finance Committee and Council in December 2004 The Chairman welcomed two new SCC members representing the Staff Association: Véronique Paris and Gianni Deroma. Expressing their best wishes for the New Year, the members of the SCC took note of a report by the Chairman on the outcome of these Committee meetings and of the Director-General's staff meeting on 10 January 2005, and discussed a number of internal follow-up actions. Work planning of the SCC & TREF The SCC agreed its calendar of ordinary sessions and its draft work planning for the first half of 2005, subject to including a number of matters outstanding from 2004. The Committee discussed internal preparation for the next meeting of TREF on 4 & 5 April devoted to items concerning the current 5-Yearly Review. The SCC also took note of the provisional scheduling of TREF meetings from May to September, which will be settled by...

  12. Fitting ordinary differential equations to short time course data.

    Science.gov (United States)

    Brewer, Daniel; Barenco, Martino; Callard, Robin; Hubank, Michael; Stark, Jaroslav

    2008-02-28

    Ordinary differential equations (ODEs) are widely used to model many systems in physics, chemistry, engineering and biology. Often one wants to compare such equations with observed time course data, and use this to estimate parameters. Surprisingly, practical algorithms for doing this are relatively poorly developed, particularly in comparison with the sophistication of numerical methods for solving both initial and boundary value problems for differential equations, and for locating and analysing bifurcations. A lack of good numerical fitting methods is particularly problematic in the context of systems biology where only a handful of time points may be available. In this paper, we present a survey of existing algorithms and describe the main approaches. We also introduce and evaluate a new efficient technique for estimating ODEs linear in parameters particularly suited to situations where noise levels are high and the number of data points is low. It employs a spline-based collocation scheme and alternates linear least squares minimization steps with repeated estimates of the noise-free values of the variables. This is reminiscent of expectation-maximization methods widely used for problems with nuisance parameters or missing data.

  13. Afterword: materialities, care, 'ordinary affects', power and politics.

    Science.gov (United States)

    Latimer, Joanna

    2018-02-01

    In this paper I explore how the papers in this volume offer ways of thinking about materialities of care in terms of political ecologies, including hierarchies of value as well as assemblages, in which strategic agendas are made present in everyday practices, with profound and ordinary affects, as well as effects. I show how power can work through the association of multiple and heterogeneous materials and social processes to create 'thresholds', as spaces through which people must pass in order to be included as patients, and which circulate specific imaginaries over what counts as an appropriate need. I go on to suggest how some material practices are made mundane and immaterial, that is inconsequential, so that by drawing attention to their importance in how care is done (or not done) the papers help disrupt the commonplace production and reproduction of the 'neglected things' (Puig de la Bellacasa ) of healthcare environments, and by so doing help reimagine what is important for occasions to actually be caring. I then shift to thinking about a sensibility, one that is highly valued in this collection of articles, that helps illuminate different imaginaries of care to those that dominate healthcare environments, an approach that I have called elsewhere 'relational extension', and in the example I offer here show how shifts in extension as a form of motility disrupts stabilities and their reproduction, to accomplish different forms of world-making. © 2018 Foundation for the Sociology of Health & Illness.

  14. On Public Influence on People's Interactions with Ordinary Biodiversity.

    Science.gov (United States)

    Skandrani, Zina; Daniel, Lucie; Jacquelin, Lauriane; Leboucher, Gérard; Bovet, Dalila; Prévot, Anne-Caroline

    2015-01-01

    Besides direct impacts of urban biodiversity on local ecosystem services, the contact of city dwellers with urban nature in their everyday life could increase their awareness on conservation issues. In this paper, we focused on a particularly common animal urban species, the feral pigeon Columba livia. Through an observational approach, we examined behavioral interactions between city dwellers and this species in the Paris metropolis, France. We found that most people (mean: 81%) do not interact with pigeons. Further, interactions (either positive or negative) are context and age-dependent: children interact more than adults and the elderly, while people in tourist spots interact more than people in urban parks or in railway stations, a result that suggests that people interacting with pigeons are mostly tourists. We discuss these results in terms of public normative pressures on city dwellers' access to and reconnection with urban nature. We call for caution in how urban species are publically portrayed and managed, given the importance of interactions with ordinary biodiversity for the fate of nature conservation.

  15. On Public Influence on People's Interactions with Ordinary Biodiversity.

    Directory of Open Access Journals (Sweden)

    Zina Skandrani

    Full Text Available Besides direct impacts of urban biodiversity on local ecosystem services, the contact of city dwellers with urban nature in their everyday life could increase their awareness on conservation issues. In this paper, we focused on a particularly common animal urban species, the feral pigeon Columba livia. Through an observational approach, we examined behavioral interactions between city dwellers and this species in the Paris metropolis, France. We found that most people (mean: 81% do not interact with pigeons. Further, interactions (either positive or negative are context and age-dependent: children interact more than adults and the elderly, while people in tourist spots interact more than people in urban parks or in railway stations, a result that suggests that people interacting with pigeons are mostly tourists. We discuss these results in terms of public normative pressures on city dwellers' access to and reconnection with urban nature. We call for caution in how urban species are publically portrayed and managed, given the importance of interactions with ordinary biodiversity for the fate of nature conservation.

  16. Numerical methods for the solution of ordinary differential equations

    CERN Document Server

    Azeem, M

    1999-01-01

    The ode 113 code solves non-stiff differential equations and is a fully variable step, variable order, PECE implementation in terms of modified divided differences of Adams-Bashforth-Moulton family of formulas of order 1-12. The main objectives of this project were to modify PECE mode of ode 113 into PEC mode, study the variable step size and variable order strategy of both the modes and finally, develop the switching strategy between both PECE and PEC modes to minimize the cost of solving the ordinary differential equations. Using some test problems (including stiff, mild stiff and non-stiff), it was found that the PEC mode was more efficient for non-stiff problems at crude and intermediate tolerances and the PECE mode for all problems at the stringent tolerance. An automatic switching strategy was developed using the results observed from the step size and order plots of all the test problems for both the modes and gave the optimum results.

  17. Quantifying uncertainty, variability and likelihood for ordinary differential equation models

    LENUS (Irish Health Repository)

    Weisse, Andrea Y

    2010-10-28

    Abstract Background In many applications, ordinary differential equation (ODE) models are subject to uncertainty or variability in initial conditions and parameters. Both, uncertainty and variability can be quantified in terms of a probability density function on the state and parameter space. Results The partial differential equation that describes the evolution of this probability density function has a form that is particularly amenable to application of the well-known method of characteristics. The value of the density at some point in time is directly accessible by the solution of the original ODE extended by a single extra dimension (for the value of the density). This leads to simple methods for studying uncertainty, variability and likelihood, with significant advantages over more traditional Monte Carlo and related approaches especially when studying regions with low probability. Conclusions While such approaches based on the method of characteristics are common practice in other disciplines, their advantages for the study of biological systems have so far remained unrecognized. Several examples illustrate performance and accuracy of the approach and its limitations.

  18. Ordinary least squares regression is indicated for studies of allometry.

    Science.gov (United States)

    Kilmer, J T; Rodríguez, R L

    2017-01-01

    When it comes to fitting simple allometric slopes through measurement data, evolutionary biologists have been torn between regression methods. On the one hand, there is the ordinary least squares (OLS) regression, which is commonly used across many disciplines of biology to fit lines through data, but which has a reputation for underestimating slopes when measurement error is present. On the other hand, there is the reduced major axis (RMA) regression, which is often recommended as a substitute for OLS regression in studies of allometry, but which has several weaknesses of its own. Here, we review statistical theory as it applies to evolutionary biology and studies of allometry. We point out that the concerns that arise from measurement error for OLS regression are small and straightforward to deal with, whereas RMA has several key properties that make it unfit for use in the field of allometry. The recommended approach for researchers interested in allometry is to use OLS regression on measurements taken with low (but realistically achievable) measurement error. If measurement error is unavoidable and relatively large, it is preferable to correct for slope attenuation rather than to turn to RMA regression, or to take the expected amount of attenuation into account when interpreting the data. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

  19. Diagnostically relevant facial gestalt information from ordinary photos.

    Science.gov (United States)

    Ferry, Quentin; Steinberg, Julia; Webber, Caleb; FitzPatrick, David R; Ponting, Chris P; Zisserman, Andrew; Nellåker, Christoffer

    2014-06-24

    Craniofacial characteristics are highly informative for clinical geneticists when diagnosing genetic diseases. As a first step towards the high-throughput diagnosis of ultra-rare developmental diseases we introduce an automatic approach that implements recent developments in computer vision. This algorithm extracts phenotypic information from ordinary non-clinical photographs and, using machine learning, models human facial dysmorphisms in a multidimensional 'Clinical Face Phenotype Space'. The space locates patients in the context of known syndromes and thereby facilitates the generation of diagnostic hypotheses. Consequently, the approach will aid clinicians by greatly narrowing (by 27.6-fold) the search space of potential diagnoses for patients with suspected developmental disorders. Furthermore, this Clinical Face Phenotype Space allows the clustering of patients by phenotype even when no known syndrome diagnosis exists, thereby aiding disease identification. We demonstrate that this approach provides a novel method for inferring causative genetic variants from clinical sequencing data through functional genetic pathway comparisons.DOI: http://dx.doi.org/10.7554/eLife.02020.001. Copyright © 2014, Ferry et al.

  20. Experimental Partial Melting of the MacAlpine Hills 02453 (CK5) Chondrite

    Science.gov (United States)

    Gardner-Vandy, K. G.; Lauretta, D. S.

    2011-03-01

    We perform partial melting experiments of CK chondrite MAC 02453 in a Deltech vertical tube furnace at 1150 ºC and 1250 ºC and oxygen fugacities of IW-1 and IW+1. We relate our results to the formation of FeO-rich primitive achondrites.

  1. Disequilibrium partial melting experiments on the Leedey L6 chondrite: textural controls on melting processes

    Science.gov (United States)

    Feldstein, S. N.; Jones, R. H.; Papike, J. J.

    2001-11-01

    A series of experiments was designed to investigate the textural and compositional changes that take place during disequilibrium partial melting of chondritic material. Chips of the L6 chondrite, Leedey, were heated at 1200 ºC and logfO2 = IW-1 for durations of 1 hour to 21 days. We observed a progression of kinetically-controlled textural changes in melt and restite minerals and changes in the liquidus mineralogy in response to factors such as volatile loss. During the course of the experiments, both olivine and orthopyroxene recrystallized at different times. Rare relict chondrules could still be identified after 21 days. The silicate melts that form are very heterogeneous, in terms of both major and trace element chemistry, reflecting heterogeneity of the localized mineral assemblage, particularly with respect to phosphates and clinopyroxene. Metal-sulfide melts formed in short-duration runs are also heterogeneous. The experimental data are relevant to aspects of the genesis of primitive achondrites such as the acapulcoites. The observed textures are consistent with a model for acapulcoite petrogenesis in which silicate melting was limited to only a few volume % of the chondritic source rock. The experiments are also relevant to the behavior of chondritic material that has been partially melted in an impact environment.

  2. Super-chondritic Sm/Nd ratios in Mars, the Earth and the Moon.

    Science.gov (United States)

    Caro, Guillaume; Bourdon, Bernard; Halliday, Alex N; Quitté, Ghylaine

    2008-03-20

    Small isotopic differences in the atomic abundance of neodymium-142 (142Nd) in silicate rocks represent the time-averaged effect of decay of formerly live samarium-146 (146Sm) and provide constraints on the timescales and mechanisms by which planetary mantles first differentiated. This chronology, however, assumes that the composition of the total planet is identical to that of primitive undifferentiated meteorites called chondrites. The difference in the 142Nd/144Nd ratio between chondrites and terrestrial samples may therefore indicate very early isolation (Mars also has a non-chondritic composition. Meteorites belonging to the shergottite subgroup define a planetary isochron yielding an age of differentiation of 40 +/- 18 Myr for the martian mantle. This isochron does not pass through the chondritic reference value (100 x epsilon(142)Nd = -21 +/- 3; 147Sm/144Nd = 0.1966). The Earth, Moon and Mars all seem to have accreted in a portion of the inner Solar System with approximately 5 per cent higher Sm/Nd ratios than material accreted in the asteroid belt. Such chemical heterogeneities may have arisen from sorting of nebular solids or from impact erosion of crustal reservoirs in planetary precursors. The 143Nd composition of the primitive mantle so defined by 142Nd is strikingly similar to the putative endmember component 'FOZO' characterized by high 3He/4He ratios.

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

    Science.gov (United States)

    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.

  4. The Colony meteorite and the possible existence of a new chemical subgroup of CO3 chondrites

    Science.gov (United States)

    Rubin, A. E.; James, J. A.; Keck, B. D.; Weeks, K. S.; Sears, D. W. G.

    1984-01-01

    The Colony meteorite, found in Oklahoma around 1975, has an unrecrystallized texture and contains heterogeneous olivine and low Ca pyroxene, kamacite with low Ni and Co and high Cr, amoeboid inclusions with low FeO and MnO, and numerous small chondrules with clear pink glass. These characteristics are shared by members of the least metamorphosed subgroup of CO3 chondrites. Colony contains a fine grained matrix that has higher FeO and K2O and lower MgO and Na2O than normal CO3 matrices. Allan Hills A77307 is another unmetamorphosed meteorite that has many petrologic similarities to normal CO chondrites, including matrix abundance, mineral compositions and chondrule size. However, it differs from them in its abundance of magnetite and presence of iron carbides. The olivine and low Ca pyroxene compositional distributions of Colony and A77307 are very similar. The shapes of the thermoluminescence glow curves of Colony and A77307 are very similar, but differ significantly from those of normal CO chondrites. It is suggested that Colony and A77307 represent a distinct chemical subgroup of CO3 chondrites, characterized by low Ni, Co, S, Ca, Mg, Mn and, possibly, high Cd.

  5. Diverse mineralogical and oxygen isotopic signatures recorded in CV3 carbonaceous chondrites

    Science.gov (United States)

    Ishida, Hatsumi; Nakamura, Tomoki; Miura, Hitoshi; Kakazu, Yuki

    2012-08-01

    We describe the petrography and mineralogy of six CV3 carbonaceous chondrites. LAP02206, LAP02228, LAP04843, and GRA06101 are classified as oxidized Allende-like chondrites (CV3oxA). RBT04143 and QUE97186 are classified as members of the reduced subtype (CV3red). Chondrules in the CV3oxA chondrites show extensive Fe-Mg zoning. Fe-rich olivine in the rims of the CV3oxA chondrules are 16O-poor relative to Mg-rich olivine in the cores, suggesting that in addition to Fe and Mg, oxygen was exchanged between chondrules and matrix during weak thermal metamorphism. The CV3red chondrites appear to have formed through various processes. QUE97186 shows chondrule flattening with a preferred orientation, which is interpreted to have resulted from shock impact at a pressure of ˜20 GPa. The post-shock residual heat (˜1000 °C) is likely to be responsible for the restricted Fe/Mg ratios of matrix olivine. Based on the degree of Fe-Mg homogenization of matrix olivines, we estimate the spatial scale of the shock-heated region to be ˜1 m. RBT04143 is a breccia containing many clasts of two types of lithologies: reduced-type material and very weakly altered material.

  6. EBSD Studies of Ringwoodite Microcrystalline Fabrics in the Shocked NWA 5011 L6 Chondritic Meteorite

    Science.gov (United States)

    Bérczi, Sz.; Nagy, Sz.; Gyollai, I.; Józsa, S.; Havancsák, K.; Dankházi, Z.; Varga, G.; Ratter, K.; Pál-Molnár, E.; Fintor, K.; Gucsik, A.

    2012-03-01

    EBSD measurements on a 2 mm × 2 mm sample of the shocked, veined NWA 5011 L6 chondrite showed that the optically homogeneous large ringwoodite minerals in the veins consist of 2-5 μm sized, variously oriented micrograins.

  7. Search for effects of a supernova explosion 30 to 40 thousand years ago in chondrites

    Science.gov (United States)

    Alexeev, V. A.; Ustinova, G. K.

    1993-01-01

    The relative increases in Al-26 and Mn-53 equilibrium radioactivity of chondrites with different cosmic-ray exposure and terrestrial ages due to a possible supernova explosion 30-40 thousand years ago have been calculated. The results are discussed.

  8. 26 CFR 1.1244(a)-1 - Loss on small business stock treated as ordinary loss.

    Science.gov (United States)

    2010-04-01

    ... other hand, stock purchased by an investment firm and subsequently resold does not qualify as section... 26 Internal Revenue 11 2010-04-01 2010-04-01 true Loss on small business stock treated as ordinary... Losses § 1.1244(a)-1 Loss on small business stock treated as ordinary loss. (a) In general. Subject to...

  9. Effects of Ordinary and Adaptive Toys on Pre-School Children with Developmental Disabilities

    Science.gov (United States)

    Hsieh, Hsieh-Chun

    2008-01-01

    Toys help children in mastering developmental tasks. This study investigated toy effect on children with developmental disabilities as they engage in using ordinary and adaptive toys. A single-subject design was used to identify the effects on their toy play abilities. Differences in toy effects between playing ordinary and adaptive toys were…

  10. 76 FR 24572 - Proposed Information Collection (Application for Ordinary Life Insurance) Activity: Comment Request

    Science.gov (United States)

    2011-05-02

    ... AFFAIRS Proposed Information Collection (Application for Ordinary Life Insurance) Activity: Comment... Insurance, Replacement Insurance for Modified Life Reduced at Age 65, National Service Life Insurance, VA Form 29-8485. b. Application for Ordinary Life Insurance, Replacement Insurance for Modified Life...

  11. First-episode psychosis patients recruited into treatment via early detection teams versus ordinary pathways

    DEFF Research Database (Denmark)

    Johannessen, Jan Olav; Joa, Inge; Auestad, Bjørn

    2011-01-01

    To compare the 5-year course and outcome of first-episode psychosis (FEP) patients recruited via active outreach detection teams (DTs) versus ordinary referral channels (not-DT).......To compare the 5-year course and outcome of first-episode psychosis (FEP) patients recruited via active outreach detection teams (DTs) versus ordinary referral channels (not-DT)....

  12. Chromium isotopic homogeneity between the Moon, the Earth, and enstatite chondrites

    Science.gov (United States)

    Mougel, Bérengère; Moynier, Frédéric; Göpel, Christa

    2018-01-01

    Among the elements exhibiting non-mass dependent isotopic variations in meteorites, chromium (Cr) has been central in arguing for an isotopic homogeneity between the Earth and the Moon, thus questioning physical models of Moon formation. However, the Cr isotopic composition of the Moon relies on two samples only, which define an average value that is slightly different from the terrestrial standard. Here, by determining the Cr isotopic composition of 17 lunar, 9 terrestrial and 5 enstatite chondrite samples, we re-assess the isotopic similarity between these different planetary bodies, and provide the first robust estimate for the Moon. In average, terrestrial and enstatite samples show similar ε54Cr. On the other hand, lunar samples show variables excesses of 53Cr and 54Cr compared to terrestrial and enstatite chondrites samples with correlated ε53Cr and ε54Cr (per 10,000 deviation of the 53Cr/52Cr and 54Cr/52Cr ratios normalized to the 50Cr/52Cr ratio from the NIST SRM 3112a Cr standard). Unlike previous suggestions, we show for the first time that cosmic irradiation can affect significantly the Cr isotopic composition of lunar materials. Moreover, we also suggest that rather than spallation reactions, neutron capture effects are the dominant process controlling the Cr isotope composition of lunar igneous rocks. This is supported by the correlation between ε53Cr and ε54Cr, and 150Sm/152Sm ratios. After correction of these effects, the average ε54Cr of the Moon is indistinguishable from the terrestrial and enstatite chondrite materials reinforcing the idea of an Earth-Moon-enstatite chondrite system homogeneity. This is compatible with the most recent scenarios of Moon formation suggesting an efficient physical homogenization after a high-energy impact on a fast spinning Earth, and/or with an impactor originating from the same reservoir in the inner proto-planetary disk as the Earth and enstatite chondrites and having similar composition.

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

    Science.gov (United States)

    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.

  14. Assessment of early attrition using an ordinary flatbed scanner.

    Science.gov (United States)

    Van't Spijker, Arie; Kreulen, Cees M; Bronkhorst, Ewald M; Creugers, Nico H J

    2012-07-01

    The aim of this study was to assess a two-dimensional method to monitor occlusal tooth wear quantitatively using a commercially available ordinary flatbed scanner. A flatbed scanner, measuring software and gypsum casts were used. In Part I, two observers (A and B) independently traced scans of marked wear facets of ten sets of casts in two sessions (test and retest). In Part II, three other sets of casts were duplicated and two observers (C and D) marked wear facets and traced the scanned images independently. Intra- and inter-observer agreement was determined comparing measured values (mm(2)) in paired T-tests. Duplicate measurement errors (DME) were calculated. In Part I the test and retest values (10 casts, 218 teeth) of observer A and B did not differ significantly (A: p = 0.289; B: p = 0.666); correlation coefficients were 0.998 (A) and 0.999 (B). "Tracing wear facets" showed a DME of 0.30 mm(2) for observer A and 0.15 mm(2) for observer B. In Part II, assessment of 70 teeth resulted in correlation coefficients of 0.994 for observer C and 0.997 for observer D; no differences between test and retest values were found for C (p = 0.061), although D differed significantly (p = 0.000). The DME for "marking and tracing wear facets" was 0.39 mm(2) (C) and 0.27 mm(2) (D). DME for inter-observer agreement were 0.45 mm(2) (test) and 0.42 mm(2) (re-test). We conclude that marking and tracing of occlusal wear facets to assess occlusal tooth wear quantitatively can be done accurately and reproducibly. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Transformation of pyroxene to akimotoite (MgSiO3-ilmenite) in NWA 5011 L6 chondrite

    Science.gov (United States)

    Nagy, S.; Gyollai, I.; Józsa, S.; Bérczi, S.; Gucsik, A.; Veres, M.

    2011-10-01

    The NWA 5011 L6 type chondrite is a heavily shocked meteorite. It contains up to 6mm wide shock melt veins (SMV). The akimotoite was firstly discovered in Tenham chondrite [1]. These shock veins attribute high pressure and high temperature to phase transformation its inside and near by its boundary. We found MgSiO3 ilmenite which clearly distinguish from the pyroxene. This high pressure phase is connecting with ringwoodite and maskelynite environment in the chondritic portion very close to boundary of the shock vein.

  16. Rare Earth Element Abundances and Pb-Pb Ages of Merrillite in Jinju H5 Chondrite: Implications to Shock Metamorphism

    Science.gov (United States)

    Goh, S.; Choi, B.-G.

    2016-08-01

    Jinju merrillite shows homogeneous REE abundances and relatively young Pb-Pb ages. Jinju H5 chondrite was probably neither equilibrated nor compacted prior to the impact and the shock made trace elements including REEs and U-Pb equilibrated.

  17. Shock-Induced Ringwoodite Rims Around Olivine Fragments in Melt Vein of Antarctic Chondrite GRV022321: Transformation Mechanism

    Science.gov (United States)

    Xie, Z.; Li, X.; Sharp, T. G.; de Carli, P. S.

    2012-03-01

    We study the formation of ringwoodite via diffusion at high temperatures and shock pressures in GRV022321 chondrite by using FIB/TEM techniques. The result suggests transformation occurred by a solid-state mechanism, enhanced by extreme deformation.

  18. High-Pressure Phases in Shock-induced Melt Veins from the Umbarger L6 Chondrite: Constraints on Shock Conditions

    Science.gov (United States)

    Xie, Z.; Tomioka, N.; Sharp, T. G.

    2001-03-01

    The Umbarger L6 chondrite contains previously unknown high-pressure phases: ringwoodite, akimotoite (MgSiO3-ilmenite), augite, and hollandite phase. Crystallization of akimotoite suggests supercooling of the melt vein during adiabatic decompression.

  19. Tuite, [gamma]-Ca32, formed by chlorapatite decomposition in a shock vein of the Suizhou L6 chondrite

    National Research Council Canada - National Science Library

    Xie, Xiande; Zhai, Shuangmeng; Chen, Ming; Yang, Hexiong

    2013-01-01

    .... This study reports the finding of tuite in a shock vein of the same Suizhou chondrite as a product of decomposition of chlorapatite, where it coexists with coarse-grained ringwoodite, majorite...

  20. Understanding the Organo-Carbonate Associations in Carbonaceous Chondrites with the Use of Micro-Raman Analysis

    Science.gov (United States)

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

    2015-01-01

    Carbonates can potentially provide sites for organic materials to accrue and develop into complex macromolecules. This study examines the organics associated with carbonates in carbonaceous chondrites using micron-Raman imaging.

  1. Oxygen- and magnesium-isotope compositions of calcium-aluminum-rich inclusions from Rumuruti (R) chondrites

    Science.gov (United States)

    Rout, S. S.; Bischoff, A.; Nagashima, K.; Krot, A. N.; Huss, G. R.; Keil, K.

    2009-07-01

    We report oxygen- and magnesium-isotope compositions of Ca,Al-rich inclusions (CAIs) from several Rumuruti (R) chondrites measured in situ using a Cameca ims-1280 ion microprobe. On a three-isotope oxygen diagram, δ 17O vs. δ 18O, compositions of individual minerals in most R CAIs analyzed fall along a slope-1 line. Based on the variations of Δ 17O values (Δ 17O = δ 17O - 0.52 × δ 18O) within individual inclusions, the R CAIs are divided into (i) 16O-rich (Δ 17O ˜ -23-26‰), (ii) uniformly 16O-depleted (Δ 17O ˜ -2‰), and (iii) isotopically heterogeneous (Δ 17O ranges from -25‰ to +5‰). One of the hibonite-rich CAIs, H030/L, has an intermediate Δ 17O value of -12‰ and a highly fractionated composition (δ 18O ˜ +47‰). We infer that like most CAIs in other chondrite groups, the R CAIs formed in an 16O-rich gaseous reservoir. The uniformly 16O-depleted and isotopically heterogeneous CAIs subsequently experienced oxygen-isotope exchange during remelting in an 16O-depleted nebular gas, possibly during R chondrite chondrule formation, and/or during fluid-assisted thermal metamorphism on the R chondrite parent asteroid. Three hibonite-bearing CAIs and one spinel-plagioclase-rich inclusion were analyzed for magnesium-isotope compositions. The CAI with the highly fractionated oxygen isotopes, H030/L, shows a resolvable excess of 26Mg ( 26Mg ∗) corresponding to an initial 26Al/ 27Al ratio of ˜7 × 10 -7. Three other CAIs show no resolvable excess of 26Mg ( 26Mg ∗). The absence of 26Mg ∗ in the spinel-plagioclase-rich CAI from a metamorphosed R chondrite NWA 753 (R3.9) could have resulted from metamorphic resetting. Two other hibonite-bearing CAIs occur in the R chondrites (NWA 1476 and NWA 2446), which appear to have experienced only minor degrees of thermal metamorphism. These inclusions could have formed from precursors with lower than canonical 26Al/ 27Al ratio.

  2. Mineralogical, crystallographic and redox features of the earliest stages of fluid alteration in CM chondrites

    Science.gov (United States)

    Pignatelli, Isabella; Marrocchi, Yves; Mugnaioli, Enrico; Bourdelle, Franck; Gounelle, Matthieu

    2017-07-01

    The CM chondrites represent the largest group of hydrated meteorites and span a wide range of conditions, from less altered (i.e., CM2) down to heavily altered (i.e., CM1). The Paris chondrite is considered the least altered CM and thus enables the earliest stages of aqueous alteration processes to be deciphered. Here, we report results from a nanoscale study of tochilinite/cronstedtite intergrowths (TCIs) in Paris-TCIs being the emblematic secondary mineral assemblages of CM chondrites, formed from the alteration of Fe-Ni metal beads (type-I TCIs) and anhydrous silicates (type-II TCIs). We combined high-resolution transmission electron microscopy, scanning transmission X-ray microscopy and electron diffraction tomography to characterize the crystal structure, crystal chemistry and redox state of TCIs. The data obtained are useful to reconstruct the alteration conditions of Paris and to compare them with those of other meteorites. Our results show that tochilinite in Paris is characterized by a high hydroxide layer content (n = 2.1-2.2) regardless of the silicate precursors. When examined alongside other CMs, it appears that the hydroxide layer and iron contents of tochilinites correlate with the degree of alteration experienced by the chondrites. The Fe3+/ΣFe ratios of TCIs are high: 8-15% in tochilinite, 33-60% in cronstedtite and 70-80% in hydroxides. These observations suggest that alteration of CM chondrites took place under oxidizing conditions that could have been induced by significant H2 release during serpentinization. Similar results were recently reported in CR chondrites (Le Guillou et al., 2015), suggesting that the process(es) controlling the redox state of the secondary mineral assemblages were quite similar in the CM and CR parent bodies despite the different alteration conditions. According to our mineralogical and crystallographic survey, the formation of TCIs in Paris occurred at temperatures lower than 100 °C, under neutral, slightly alkaline

  3. Stanley Cavell, Classical Hollywood and the Constitution of the Ordinary (With Notes on Billy Wilder

    Directory of Open Access Journals (Sweden)

    Tatjana Jukić

    2016-04-01

    Full Text Available When in his Tanner lectures Stanley Cavell sets out to define Ordinary Language Philosophy or – rather – to explain how it demarcates philosophy as such, he takes up psychoanalytic literary criticism in order to articulate the terms of this task. Yet the constitution of the ordinary, in Cavell, is never quite accessed from within psychoanalysis-cum-literature alone; instead, it takes another relation, that of psychoanalysis and literature to classical Hollywood, for Cavell to address the ordinary in terms of its constitution. I propose to discuss this complex using two films by Billy Wilder as a passageway to Cavell’s analytic procedure.

  4. Sumudu Transform Method for Analytical Solutions of Fractional Type Ordinary Differential Equations

    Directory of Open Access Journals (Sweden)

    Seyma Tuluce Demiray

    2015-01-01

    Full Text Available We make use of the so-called Sumudu transform method (STM, a type of ordinary differential equations with both integer and noninteger order derivative. Firstly, we give the properties of STM, and then we directly apply it to fractional type ordinary differential equations, both homogeneous and inhomogeneous ones. We obtain exact solutions of fractional type ordinary differential equations, both homogeneous and inhomogeneous, by using STM. We present some numerical simulations of the obtained solutions and exhibit two-dimensional graphics by means of Mathematica tools. The method used here is highly efficient, powerful, and confidential tool in terms of finding exact solutions.

  5. Occurrence and possible significance of rare Ti oxides (Magneli phases) in carbonaceous chondrite matrices

    Science.gov (United States)

    Brearley, Adrian J.

    1993-01-01

    Rare, ultrafine-grained Ti oxides (Ti3O5 and the Magneli phases, Ti5O9 and Ti8O15) have been identified by TEM in the CM2 carbonaceous chondrite, Bells, and a carbonaceous chondrite matrix clast from the Nilpena polymict ureilite. In both meteorites the Ti oxides occur in the matrix as isolated grains and clusters of two or more grains. They are euhedral in shape and have grain sizes of 0.05-0.3 micron. Magneli phases have been recently shown to be a common component in some interplanetary dust particles, but this is the first reported occurrence in a meteorite. The morphological properties and grain size of the Ti oxides are consistent with formation by vapor phase condensation either within the solar nebula or possibly in a presolar environment.

  6. IR reflectance spectra of pristine Antarctic CM chondrites to characterize Marco Polo-R mission target

    Science.gov (United States)

    Trigo-Rodríguez, J. M.; Moyano-Cambero, C. E.; Llorca, J.; Alonso-Azcárate, J.; Fornasier, S.; Belskaya, I.; Binzel, R.; Rivkin, A. S.

    2012-09-01

    The hydrated groups of carbonaceous chondrites (hereafter CCs) exhibit different degrees of aqueous alteration. Primary minerals were transformed in their parent bodies by the action of the water. Most of the water was probably accreted as ice or bounded in hydrated minerals. Moderate heating associated with residual radioactivity or collisional compaction released that water to soak temporarily the materials forming these asteroids. Evidence for static and dynamic aqueous mineral products has been described [1, 2], at the same time that the different degrees of alteration exhibited for members of the CM group were characterized [3, 4]. We apply here a new IR spectroscopic technique that allows to assess the amount of adsorbed water present in minerals forming carbonaceous chondrites.

  7. Noble gas concentrations and cosmic ray exposure ages of eight recently fallen chondrites

    Science.gov (United States)

    Bogard, D. D.; Reynolds, M. A.; Simms, L. A.

    1973-01-01

    Abundances and isotopic compositions of He, Ne, Ar, and Xe have been measured in eight recently fallen chondrites. Ratios of concentrations of cosmic ray-produced He-3, Ne-21, Ne-22, and Ar-38 indicate that all eight samples experienced less than average cosmic ray shielding. He-3 and Ne-21 exposure ages were calculated using shielding corrected chondritic production rates and the measured Ne-22/Ne-21. Exposure ages calculated from Na-22/Ne-22 and Al-26/Ne-21 ratios and constant relative production rates show a bias between the two ages due to variations in Na-22/Al-26. Arguments are presented that this bias is due to irradiation hardness differences, and therefore the use of constant values for both the Na-22/Ne-22 and Al-26/Ne-21 production ratios is not permitted.

  8. Trace elements in chondritic stratospheric particles - Zinc depletion as a possible indicator of atmospheric entry heating

    Science.gov (United States)

    Flynn, G. J.; Sutton, S. R.

    1992-01-01

    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 Allende meteorite sample in their HSC EDX spectra, exhibit chondritic 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 chondritic 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.

  9. Noble gases, nitrogen and cosmic ray exposure age of the Sulagiri chondrite

    Directory of Open Access Journals (Sweden)

    Ramakant R. Mahajan

    2017-01-01

    Full Text Available The Sulagiri meteorite fell in India on 12 September 2008, LL6 chondrite class is the largest among all the Indian meteorites. Isotopic compositions of noble gases (He, Ne, Ar, Kr and Xe and nitrogen in the Sulagiri meteorite and cosmic ray exposure history are discussed. Low cosmogenic (22Ne/21Nec ratio is consistent with irradiation in a large body. Cosmogenic noble gases indicate that Sulagiri has a 4π cosmic-ray exposure (CRE age of 27.9 ± 3.4 Ma and is a member of the peak of CRE age distribution of LL chondrites. Radiogenic 4He and 40Ar concentrations in Sulagiri yields the radiogenic ages as 2.29 and 4.56 Ga, indicating the loss of He from the meteorite. Xenon and krypton are mixture of Q and spallogenic components.

  10. Mineralogy and petrology of the Abee enstatite chondrite breccia and its dark inclusions

    Science.gov (United States)

    Rubin, A. E.; Keil, K.

    1983-01-01

    A model is proposed for the petrogenesis of the Abee E4 enstatite chondrite breccia, which consists of clasts, dark inclusions and matrix, and whose dark inclusions are an unusual kind of enstatite chondritic material. When the maximum metamorphic temperature of the breccia parent material was greater than 840 C, euhedral enstatite crystals in metallic Fe, Ni, and sulfide-rich areas grew into pliable metal and sulfide. Breccia parent material was impact-excavated, admixed with dark inclusions, and rapidly cooled. During this cooling, the clast and matrix material acquired thermal remanent magnetization. A subsequent ambient magnetic field imparted a uniform net magnetic orientation to the matrix and caused the magnetic orientation of the clasts to be less random. The Abee breccia was later consolidated by shock or by shallow burial and long period, low temperature metamorphism.

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

    Science.gov (United States)

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

    2015-10-13

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

  12. Mineralogical aspects of terrestrial weathering effects in chondrites from Allan Hills, Antarctica

    Science.gov (United States)

    Gooding, J. L.

    1982-01-01

    The work reported here represents a first attempt at comparing the mineralogical aspects of weathering effects in selected Antarctic chondrites with those present in a petrologically similar chondrite which was weathered in the Arizona desert. The methods of analysis employed include X-ray diffractometry, differential thermal analysis, and reflectance spectrophotometry. It is found that the dominant weathering products in the rocks are complex, multiple-phase, hydrous ferric oxides which formed by alteration of Ni-Fe metal and sulfide particles under the influence of liquid water. The Fe-oxide weathering products may comprise approximately 15-20 wt % of the most intensely weathered samples although the same samples contain not more than 5% goethite as the only well-crystallized hydrous ferric oxide.

  13. Isotope composition of Cd, Ca and Mg in the Brownfield chondrite

    Energy Technology Data Exchange (ETDEWEB)

    Rosman, K.J.R.; Barnes, I.L.; Moore, L.J.; Gramlich, J.W. (National Bureau of Standards, Washington, DC (USA))

    1980-01-01

    The isotopic composition of cadmium, calcium and magnesium in the Brownfield chondrite have been measured. The measurements on cadmium show that this element is isotopically fractionated with the heavier isotopes relatively enriched to the extent of 0.27% per mass unit. This confirms earlier reports by ROSMAN and DE LAETER (1976, 1978). Calcium and magnesium show no evidence of isotope fractionation, indicating that the process responsible for fractionating cadmium dose not seem to have affected these more refractory elements.

  14. Smyer H-Chondrite Impact-Melt Breccia and Evidence for Sulfur Vaporization

    Science.gov (United States)

    Rubin, Alan E.

    2002-01-01

    Smyer is an H-chondrite impact-melt breccia containing approx.20 vol% 0.5- to 13-mm-thick silicate-rich melt veins surrounding unmelted subrounded chondritic clasts up to 7 cm in maximum dimension. At the interface between some of the melt veins and chondritic clasts, there are troilite-rich regions consisting of unmelted. crushed 0.2- to 140-micron-size angular silicate grains and chondrule fragments surrounded by troilite and transected by thin troilite veins. Troilite fills every available fracture in the silicates. including some as thin as 0.1 microns. Little metallic Fe-Ni is present in these regions: the FeS/Fe modal ratio ranges from -25: 1 to approx.500: 1, far higher than the eutectic weight ratio of 7.5: 1. The texture of these regions indicates that the sulfide formed from a fluid of very low viscosity. The moderately high viscosity (0.2 poise) and large surface tension of liquid FeS, its inability to wet silicate grain surfaces at low oxygen fugacities. and the supereutectic FeS/Fe ratios in the troilite-rich regions indicate that the fluid was a vapor. It seems likely that during the shock event that melted Smyer, many silicates adjacent to the melt veins were crushed. Upon release of shock pressure. some of the troilite evaporated and dissociated. Molecules of S2 were transported and condensed into fractures and around tiny silicate grains: there, they combined with Fe from small adjacent metallic Fe-Ni grains to form troilite. The Ni content at the edges of some of these metal grains increased significantly; Co from these Ni-rich grains diffused into nearby kamacite. Impact-induced S volatilization may have played a major role in depleting the surface of 433 Eros (and other chondritic asteroids) in S.

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

    Science.gov (United States)

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

    1999-01-01

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

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

    Science.gov (United States)

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

    2012-01-01

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

  17. Nature of the H chondrite parent body regolith: evidence from the Dimmitt breccia.

    Science.gov (United States)

    Rubin, A. E.; Scott, E. R. D.; Taylor, G. J.; Keil, K.; Allen, J. S. B.; Mayeda, T. K.; Clayton, R. N.; Bogard, D. D.

    The authors report a study of the matrix and 21 clasts of various sizes (0.2 - 24 mm) in the Dimmitt H chondrite regolith breccia using petrographic and electron microprobe techniques. In addition, oxygen isotope studies of three clasts (DT1, DT3, and DT4) and instrumental neutron activation analysis and 39Ar/40Ar age dating of one clast (DT4) are reported.

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

    Science.gov (United States)

    Jenniskens, Peter; Rubin, Alan E.; Yin, Qing Zhu; Sears, Derek W. G.; Sandford, Scott A.; Zolensky, Michael E.; Krot, Alexander N.; Blair, Leigh; Kane, Daci; Utas, Jason; hide

    2014-01-01

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

  19. Antiperiodic Boundary Value Problems for Second-Order Impulsive Ordinary Differential Equations

    Directory of Open Access Journals (Sweden)

    2009-02-01

    Full Text Available We consider a second-order ordinary differential equation with antiperiodic boundary conditions and impulses. By using Schaefer's fixed-point theorem, some existence results are obtained.

  20. Review of Ordinary High Water Mark Indicators for Delineating Arid Streams in the Southwestern United States

    National Research Council Canada - National Science Library

    Lichvar, Robert

    2004-01-01

    ...). Unlike wetlands, for which there are criteria for hydrology, soils, and vegetation specified in a national wetland delineation manual, there is no hydrologic definition of ordinary high water (OHW...

  1. Parametric decay instability of an obliquely propagating ordinary wave in the electron cyclotron frequency range

    Science.gov (United States)

    Gusakov, E. Z.; Popov, A. Yu.

    2018-01-01

    The possibility of the low-power-threshold parametric decay of an obliquely propagating ordinary wave to an upper hybrid wave and a low-hybrid wave is analysed under conditions of nonmonotonic plasma density profile in a magnetic trap. The instability threshold and growth rate are derived explicitly. The analytical results are illustrated under the conditions typical of the ordinary mode fundamental electron cyclotron resonance heating harmonic experiments at the FTU tokamak.

  2. An Adaptive Parallel Integrator of Ordinary Differential Equations System for Space Experiment Simulation

    OpenAIRE

    Atanassov, Atanas Marinov

    2010-01-01

    Different possible sources are discussed for enhancement of the calculation time when solving ordinary differential equations systems to forecast space objects' motion. This paper presents an approach for building an integrator of ordinary differential equations systems for simultaneous solving of motion equations of multiple objects. A parallelization of calculation on the base of threads is offered. A method for synchronization is presented. The technological advance and the invasion of mul...

  3. Low-threshold parametric decay of the ordinary wave in ECRH experiments at toroidal devices

    Science.gov (United States)

    Gusakov, E. Z.; Popov, A. Yu; Saveliev, A. N.; Sysoeva, E. V.

    2017-07-01

    In this paper we analyse low-threshold parametric decay instability (PDI) of the ordinary wave in first harmonic O-mode ECRH experiments at toroidal devices. The corresponding expressions for the PDI power threshold and its growth rate are derived analytically and evaluated numerically for the conditions of the ECRH experiments on the W7-A stellarator. The possibility of low-threshold parametric decay of the pump ordinary wave on the FTU tokamak is also considered.

  4. Mass spectrometric isotope dilution analyses of palladium, silver, cadmium and tellurium in carbonaceous chondrites

    Energy Technology Data Exchange (ETDEWEB)

    Loss, R.D.; Rosman, K.J.R.; De Laeter, J. (Western Australian Inst. of Tech., Bentley. Dept. of Applied Physics)

    1984-08-01

    The mass spectrometric isotope dilution technique was used to measure the elemental abundances of Pd, Ag, Cd and Te in Orgueil (C1), Ivuna (C1), Murray (C2) and Allende (C3) chondrites. The Pd abundance of 554 ppb for the Cl chondrites is almost identical to the recommended value of Anders and Ebihara (1982); that for Cd (712 ppb) is approximately 5% higher, whereas that for Ag (198 ppb) is approximately 10% lower than the recommended values. A smooth distribution for the abundances of the odd-A nuclides between 65 <= A <= 209 have been observed except for small irregularities in the Pd-Ag-Cd and the Sm-Eu mass regions. The results from the present work have the effect of smoothing out the dip in the Pd-Ag-Cd region and indicate that there is no systematic fractionation of cosmochemical element groups in this mass region. A Te abundance of 2.25 ppm has been determined for the Cl chondrites Orgueil and Ivuna in agreement with the value of Smith et al. (1977). This value is some 30% lower than the value of Kraehenbuehl et al. (1973) but is in good agreement with the more recent measurements from Chicago. The Kraehenbuehl et al. value causes /sup 128/Te and /sup 130/Te to lie approximately 30% above the r-process peak at A = 130, whereas the new value fits smoothly into the general trend.

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

    Science.gov (United States)

    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 (spatial distribution of a broad range of organic species at the micron scale in the freshly exposed matrices of the Bells, Tagish Lake and Murchison (CM2) carbonaceous chondrites.

  6. The Relationship Between Cosmic-Ray Exposure Ages And Mixing Of CM Chondrite Lithologies

    Science.gov (United States)

    Zolensky, M. E.; Takenouchi, A.; Gregory, T.; Nishiizumi, K.; Caffee, M.; Velbel, M. A.; Ross, K.; Zolensky, A.; Le, L.; Imae, N.; hide

    2017-01-01

    Carbonaceous (C) chondrites are primitive materials probably deriving from C, P and D asteroids, and as such potentially include samples and analogues of the target asteroids of the Dawn, Hayabusa2 and OSIRIS-Rex missions. Foremost among the C chondrites are the CM chondrites, the most common type, and which have experienced the widest range of early solar system processes including oxidation, hydration, metamorphism, and impact shock deformation, often repeatedly or cyclically [1]. To track the activity of these processes in the early solar system, it is critical to learn how many separate bodies are represented by the CMs. Nishiizumi and Caffee [2] have reported that the CMs are unique in displaying several distinct peaks for cosmic-ray exposure (CRE) age groups, and that excavation from significant depth and exposure as small entities in space is the best explanation for the observed radionuclide data. There are either 3 or 4 CRE groups for CMs (Fig.1). We decided to systematically characterize the petrography in each of the CRE age groups to determine whether the groups have significant petrographic differences with these reflecting different parent asteroid geological processing or multiple original bodies. We previously re-ported preliminary results of our work [3], however we have now reexamined these meteorites from the perspective of brecciation, with interesting new results.

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

    Science.gov (United States)

    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.

  8. Coherent and subsequent incoherent ringwoodite growth in olivine of shocked L6 chondrites

    Science.gov (United States)

    Miyahara, Masaaki; Ohtani, Eiji; Kimura, Makoto; El Goresy, Ahmed; Ozawa, Shin; Nagase, Toshiro; Nishijima, Masahiko; Hiraga, Kenji

    2010-06-01

    Pervasive replacement of original olivine grains by ringwoodite adjacent to a shock-melt vein of Yamato 791384 L6 chondrite was observed with a FEG-SEM. In these olivines, we observed three distinct olivine-ringwoodite textures arranged in a spatially successive arrangement from the wall of the shock-melt vein into the olivine grains: (1) polycrystalline ringwoodite, (2) oriented several sets of ringwoodite lamellae and (3) oriented single lamellae. TEM images show that the polycrystalline and oriented several sets of lamellae parts consist of polycrystalline ringwoodite, indicating that phase transformation from olivine to ringwoodite is controlled by incoherent growth mechanism. On the other hand, the set of oriented single lamellae consists of thin ringwoodite platelets (chondrite. However, our TEM studies revealed evidence for formation of the coherent intracrystalline lamella growth mechanism then followed by incoherent growth in the shocked chondrite in nature, thus allowing to constrain a robust time scale of the shock and at the origin of the veins.

  9. Silicate darkening in the Kobe CK Chondrite: Evidence for shock metamorphism at high temperature

    Science.gov (United States)

    Tomeoka, Kazushige; Ohnishi, Ichiro; Nakamura, Noboru

    2001-11-01

    The Kobe CK4 chondrite, like most metamorphosed CK chondrites, exhibits pronounced silicate darkening of matrix and chondrule mesostases. Our petrographic and scanning electron microscopic study reveals that the matrix of Kobe consists mostly of intermixtures of two types of fine-grained olivine. One forms subhedral to anhedral normal crystals. The other fills interstices of the subhedral to anhedral olivine crystals, exhibiting a complex network of veinlets. The latter type of olivine contains high densities of small spherical vesicles (chlorapatite. The vesicular olivine is particularly abundant in regions of matrix that exhibit a relatively high degree of darkening and commonly fills chondrule mesostases. The vesicular olivine is clearly the principal cause of the silicate darkening in Kobe. The internal texture of the vesicular olivine closely resembles those of local melts produced from the matrices of experimentally and naturally shocked carbonaceous chondrites. The occurrence and texture of the vesicular olivine suggest that it resulted from recrystallization of partially melted matrix olivine by shock. Kobe exhibits light shock effects in olivine that are consistent with shock stage S2 that is too low to explain the occurrence of olivine melting. We suggest that the vesicular olivine in Kobe was produced by shock metamorphism at a relatively mild shock pressure (600 °C). Thus, it is probable that the shock effects in olivine, manifest as fracturing and deformation, were relatively minor, but heating was strong enough to cause partial melting of matrix olivine.

  10. Ordinary kriging as a tool to estimate historical daily streamflow records

    Science.gov (United States)

    Farmer, William H.

    2016-01-01

    Efficient and responsible management of water resources relies on accurate streamflow records. However, many watersheds are ungaged, limiting the ability to assess and understand local hydrology. Several tools have been developed to alleviate this data scarcity, but few provide continuous daily streamflow records at individual streamgages within an entire region. Building on the history of hydrologic mapping, ordinary kriging was extended to predict daily streamflow time series on a regional basis. Pooling parameters to estimate a single, time-invariant characterization of spatial semivariance structure is shown to produce accurate reproduction of streamflow. This approach is contrasted with a time-varying series of variograms, representing the temporal evolution and behavior of the spatial semivariance structure. Furthermore, the ordinary kriging approach is shown to produce more accurate time series than more common, single-index hydrologic transfers. A comparison between topological kriging and ordinary kriging is less definitive, showing the ordinary kriging approach to be significantly inferior in terms of Nash–Sutcliffe model efficiencies while maintaining significantly superior performance measured by root mean squared errors. Given the similarity of performance and the computational efficiency of ordinary kriging, it is concluded that ordinary kriging is useful for first-order approximation of daily streamflow time series in ungaged watersheds.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-01-14

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

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

    Science.gov (United States)

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

    2014-12-01

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

  13. Absorption of effervescent paracetamol tablets relative to ordinary paracetamol tablets in healthy volunteers.

    Science.gov (United States)

    Rygnestad, T; Zahlsen, K; Samdal, F A

    2000-05-01

    The aim of this study was to compare the rate of absorption between ordinary paracetamol tablets and effervescent paracetamol tablets. Twenty healthy volunteers participated in an open randomised crossover study and were given a 1000-mg dose of either ordinary paracetamol tablets (2 x 500 mg Panodil tablets, SmithKline Beecham) or effervescent paracetamol tablets (2 x 500 mg Pinex Brusetablett, Alpharma AS) with a 3-week washout period in between. Blood samples were collected for 3 h. Maximum serum concentration (Cmax) and the time to maximum serum concentration (tmax) were recorded and the area under the concentration versus time curve (AUC) was calculated. The mean tmax was significantly shorter when paracetamol effervescent tablets were taken (27 min) rather than ordinary paracetamol tablets (45 min) (P = 0.004). There was no significant difference between the mean Cmax of 143 micromol/l with effervescent tablets and that of 131 micromol/l with ordinary tablets. The mean AUC(0-3 h) was significantly higher with paracetamol effervescent tablets (223.8 micromol x h x l(-1)) than with ordinary tablets (198.2 micromol x h x l(-1); P = 0.003). After 15 min, 17 (85%) subjects in the effervescent group had a serum concentration of 70 micromol/l (lower therapeutic serum concentration) or higher relative to only 2 (10%) subjects in the ordinary tablet group (P = 0.001). Paracetamol effervescent tablets are absorbed significantly faster than ordinary paracetamol. Thus, effervescent tablets might offer significantly faster pain relief when paracetamol is used.

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

    Science.gov (United States)

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

    2014-12-01

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

  15. LEW 88180, LEW 87119, and ALH 85119: New EH6, EL7, and EL4 Enstatite Chondrites

    Science.gov (United States)

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

    1993-07-01

    The EH and EL chondrites formed in a uniquely reducing environment, containing low-Fe pyroxene, abundant metal, and a number of unusual sulphides and other minerals [1]. An important aspect of their history is that while the EL chondrites consist predominantly of metamorphosed meteorites, the EH consist primarily of little-metamorphosed meteorites (e.g., [2]), and yet EL chondrites have lower equilibrium temperatures than EH chondrite [3,4]. To help understand this observation and its implication for the history of the classes, we have been searching for new enstatite chondrites, looking especially for meteorites of previously unknown chemical-petrologic class. Using our normal INAA methods [5] and sample splits of 100-200 mg, the bulk composition of nine Antarctic enstatite chondrites and one fall were determined. The data were used to assign the meteorites to chemical classes, the Ni/Ir vs. Al/V plot (Fig. 1) being especially useful since it uses the refractory element difference between EH and EL chondrites and is insensitive to metal-silicate heterogeneity. The well-analyzed Qingzhen was included to check our method. ALH84170, ALH84206, and EET87746, which Mason described as E3, E4, and E4 were all found to be EH chondrites [6]. Our data for the three paired EL3 chondrites were discussed earlier (MAC88136, 88180, and 88184) [7,8]. LEW88180, LEW87119, and ALH85119, which Mason described as type E6, E6, and E4 respectively [6], are EH, EL, and EL; thus LEW88180 and ALH85119 appear to be the first EH6 and EL4 chondrites. The compositions of kamacite, phosphide, and niningerite-alabandite (Fig. 2) for ALH84170, ALH84206, EET87746, LEW88180, and ALH85119 are consistent with Mason's petrologic type assignments [6]. The mineral composition of LEW88180 (2.7% Si and 9.4% Ni in the kamacite, 7.8% Ni in the phosphide, and 60% FeS in the niningerite) confirms our classification of this meteorite as EH6. ALH85119 contains kamacite with 0.5% Si and 7% Ni, phosphide with 46

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

    Science.gov (United States)

    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.

  17. Ordinary Social Interaction and the Main Effect Between Perceived Support and Affect.

    Science.gov (United States)

    Lakey, Brian; Vander Molen, Randy J; Fles, Elizabeth; Andrews, Justin

    2016-10-01

    Relational regulation theory hypothesizes that (a) the main effect between perceived support and mental health primarily reflects ordinary social interaction rather than conversations about stress and how to cope with it, and (b) the extent to which a provider regulates a recipient's mental health primarily reflects the recipient's personal taste (i.e., is relational), rather than the provider's objective supportiveness. In three round-robin studies, participants rated each other on supportiveness and the quality of ordinary social interaction, as well as their own affect when interacting with each other. Samples included marines about to deploy to Afghanistan (N = 100; 150 dyads), students sharing apartments (N = 64; 96 dyads), and strangers (N = 48; 72 dyads). Perceived support and ordinary social interaction were primarily relational, and most of perceived support's main effect on positive affect was redundant with ordinary social interaction. The main effect between perceived support and affect emerged among strangers after brief text conversations, and these links were partially verified by independent observers. Findings for negative affect were less consistent with theory. Ordinary social interaction appears to be able to explain much of the main effect between perceived support and positive affect. © 2015 Wiley Periodicals, Inc.

  18. Hearing-impaired students' reading skills in exceptional and ordinary schools

    Directory of Open Access Journals (Sweden)

    Aliasghar Kakojoibari

    2012-12-01

    Full Text Available Background and Aim: Reading skills, a complicated process, should be learnt and solely is not depend on sounds conforming with the written symbols on a page. Readers will be able to understand and perceive the deeper meaning of the text based on their experiences and knowledge obtained through reading. This research aimed to compare hearing-impaired students' reading literacy in exceptional and ordinary schools in Iran.Methods: This cross-sectional study was done on 28 hearing-impaired students of the 4th year of primary exceptional and ordinary schools of Shahr-e-Ray and Shahryar cities, Iran, using the Progress in International Reading Literacy Study (PIRLS 2006 booklets. Comparative statistical analysis was performed using Student's t-test.Results: The hearing-impaired students in ordinary schools had significantly (p<0.05 higher scores [mean (SD] in reading literacy [3.67 (1.74], comprehension of informational contents [4.21 (2.48], and comprehension of literary contents [3.14(1.23] than hearing-impaired students in exceptional schools [1.78 (1.06, 1.92 (1.49, and 1.64 (1.62, respectively].Conclusion: Hearing-impaired students in ordinary schools meaningfully had higher performance of reading skills in comparison with hearing-impaired students in exceptional schools. It seems that an appropriate cultural bed should be provided in order to conduct these students and accept them in ordinary schools.

  19. Effect of Fast Freeze-Thaw Cycles on Mechanical Properties of Ordinary-Air-Entrained Concrete

    Directory of Open Access Journals (Sweden)

    Huai-shuai Shang

    2014-01-01

    Full Text Available Freezing-thawing resistance is a very significant characteristic for concrete in severe environment (such as cold region with the lowest temperature below 0°C. In this study, ordinary-air-entrained (O-A-E concrete was produced in a laboratory environment; the compressive strength, cubic compressive strength of C50, C40, C30, C25, and C20 ordinary-air-entrained concrete, tensile strength, and cleavage strength of C30 ordinary-air-entrained concrete were measured after fast freeze-thaw cycles. The effects of fast freeze-thaw cycles on the mechanical properties (compressive strength and cleavage strength of ordinary-air-entrained concrete materials are investigated on the basis of the experimental results. And the concise mathematical formula between mechanical behavior and number of fast freeze-thaw cycles was established. The experiment results can be used as a reference in design, maintenance, and life prediction of ordinary-air-entrained concrete structure (such as dam, offshore platform, etc. in cold regions.

  20. Including and teaching blind children in ordinary classrooms Teaching tools teachers use and their influence on the inclusion of blind children ordinary classrooms in a primary school

    OpenAIRE

    Niwagaba, Gilbert

    2014-01-01

    The study aims to investigate what teaching tools do teachers use and how do these tools influence on the inclusion of blind children in ordinary classrooms in a primary school. The study used qualitative approach and Interview method with teachers from one primary school. In depth interviews were chosen as the main instrument of data collection. Purposeful sampling and qualitative analysis was used in exploring and investigating the phenomenon of the study. Three special needs teachers for t...

  1. Low-T Thermochronology of St. Severin LL6 Chondrite Revealed from Single-Grain Phosphate (U-Th)/He Ages

    Science.gov (United States)

    Min, K.; Reiners, P. W.; Shuster, D. L.

    2011-03-01

    Low-T thermal history of St. Severin LL6 chondrite was constrained from single-grain (U-Th)/He dating for five chlorapatite and fourteen merrillite aggregates. We also present the new He diffusion data for merrillite from Guarena chondrite.

  2. Communication: Surface-facilitated softening of ordinary and vapor-deposited glasses

    Science.gov (United States)

    Cubeta, Ulyana; Bhattacharya, Deepanjan; Sadtchenko, Vlad

    2017-08-01

    A common distinction between the ordinary glasses formed by melt cooling and the stable amorphous films formed by vapor deposition is the apparent mechanism of their devitrification. Using quasi-adiabatic, fast scanning calorimetry that is capable of heating rates in excess of 105 K s-1, we have investigated the softening kinetics of micrometer-scale, ordinary glass films of methylbenzene and 2-propanol. At the limit of high heating rates, the transformation mechanism of ordinary glasses is identical to that of their stable vapor-deposited counterparts. In both cases, softening is likely to begin at the sample surface and progress into its bulk via a transformation front. Furthermore, such a surface-facilitated mechanism complies with zero-order, Arrhenius rate law. The activation energy barriers for the softening transformation imply that the kinetics must be defined, at least in part, by the initial thermodynamic and structural state of the samples.

  3. Investigation of organo-carbonate associations in carbonaceous chondrites by Raman spectroscopy

    Science.gov (United States)

    Chan, Queenie H. S.; Zolensky, Michael E.; Bodnar, Robert J.; Farley, Charles; Cheung, Jacob C. H.

    2017-03-01

    Carbonates record information regarding the timing, nature and conditions of the fluids circulating through asteroid parent bodies during aqueous alteration events. Determining carbonate abundances and their relationships with organic matter improves our understanding of the genesis of major carbonaceous components in chondritic materials. In this study, five CM2 carbonaceous chondrites (CM2.2 Nogoya, CM2.3 Jbilet Winselwan, CM2.5 Murchison, CM2 Santa Cruz, and CM2TII Wisconsin Range 91600) were studied with Raman spectroscopy. Carbonates were identified in these meteorite samples by the distinctive Raman band in the ∼1100 cm-1 region, representing the symmetric stretching vibration mode (ν1) of the (CO3)2- anion. Carbonates identified in the meteorite samples are all calcite, with the exception of a single dolomite grain in Nogoya. The v1 positions of the CM calcites are 2-3 cm-1 higher than in pure calcite, which suggests that they contain significant impurity cations. Typical graphitic first-order D and G bands were identified in the meteorite matrix as well as in ∼25% of the analyzed carbonate grains. From the Raman results, we postulate that the carbonates might not have formed under equilibrium conditions from a single fluid. The first generation of carbonate is interpreted to have formed from highly oxidized fluids that led to the oxidation of organic matter (OM) and produced carbonates that are OM-barren. The second generation of carbonate was formed from a more evolved aqueous fluid with the presence of OM. The Raman parameters of the organics in carbonates clearly deviate from the matrix OM which suggests that the carbonate organics contain very different carbonaceous components that are distinct from the typical amorphous OM of the CM matrix. The occurrence of different generations of carbonate in close proximity may be partly responsible for the wide range in estimated ages of carbonates in carbonaceous chondrites reported in previous studies.

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

    Science.gov (United States)

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

    2017-09-01

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

  5. Petrologic evolution of CM chondrites: The difficulty of discriminating between nebular and parent-body effects

    Science.gov (United States)

    Kerridge, J. F.; McSween, H. Y., Jr.; Bunch, T. E.

    1994-07-01

    We wish to draw attention to a major controversy that has arisen in the area of CM-chondrite petrology. The problem is important because its resolution will have profound implications for ideas concerning nebular dynamics, gas-solid interactions in the nebula, and accretionary processes in the nebula, among other issues. On the one hand, cogent arguments have been presented that 'accretionary dust mantles,' were formed in the solar nebula prior to accretion of the CM parent asteroid(s). On the other hand, no-less-powerful arguments have been advanced that a significant fraction of the CM lithology is secondary, produced by aqueous alteration in the near-surface regions of an asteroid-sized object. Because most, if not all, CM chondrites are breccias, these two views could coexist harmoniously, were it not for the fact that some of the coarse-grained lithologies surrounded by 'accretion dust mantles' are themselves of apparently secondary origin. Such an observation must clearly force a reassessment of one or both of the present schools of thought. Our objective here is to stimulate such a reassessment. Four possible resolutions of this conflict may be postulated. First, perhaps nature found a way of permitting such secondary alteration to take place in the nebula. Second, maybe dust mantles could form in a regolith, rather than a nebular, environment. Third, it is possible that dust mantles around secondary lithologies are different from those around primary lithologies. Finally, perhaps formation of CM chondrites involved a more complex sequence of events than visualized so far, so that some apparently 'primary' processes postdated certain 'secondary' processes.

  6. 39Ar-40Ar chronology of the enstatite chondrite parent bodies

    Science.gov (United States)

    Hopp, Jens; Trieloff, Mario; Ott, Uli; Korochantseva, Ekaterina V.; Buykin, Alexey I.

    2014-03-01

    Ar-Ar isochron ages of EL chondrites suggest closure of the K-Ar system at 4.49 ± 0.01 Ga for EL5 and 6 chondrites, and 4.45 ± 0.01 Ga for EL3 MAC 88136. The high-temperature release regimes contain a mixture of radiogenic 40Ar* and trapped primordial argon (solar or Q-type) with 40Ar/36ArTR ~ 0, which does not affect the 40Ar budget. The low-temperature extractions show evidence of an excess 40Ar component. The 40Ar/36Ar is 180-270; it is defined by intercept values of isochron regression. Excess 40Ar is only detectable in petrologic types >4/5. These lost most of their primordial 36Ar from low-temperature phases during metamorphism and retrapped excess 40Ar. The origin of this excess 40Ar component is probably related to metamorphic Ar mobilization, homogenization of primordial and in situ radiogenic Ar, and trapping of Ar by distinct low-temperature phases. Ar-Ar ages of EH chondrites are more variable and show clear evidence of a major impact-induced partial resetting at about 2.2 Ga ago or alternatively, prolonged metamorphic decomposition of major K carrier phases. EH impact melt LAP 02225 displayed the highest Ar-Ar isochron age of 4.53 ± 0.01 Ga. This age sets a limit of about 25-45 Ma for the age bias between the K-Ar and U-Pb decay systems.

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

    Science.gov (United States)

    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. Chondrules in CK carbonaceous chondrites and thermal history of the CV-CK parent body

    Science.gov (United States)

    Chaumard, NoëL.; Devouard, Bertrand

    2016-03-01

    CK chondrites are the only group of carbonaceous chondrites with petrologic types ranging from 3 to 6. It is commonly reported than ~15 vol% of CK4-6 samples are composed of chondrules. The modal abundance of chondrules estimated here for 18 CK3-6 (including five CK3s) ranges from zero (totally recrystallized) to 50.5%. Although almost all chemically re-equilibrated with the host matrix, we recognized in CK3s and Tanezrouft (Tnz) 057 (CK4) up to 85% of chondrules as former type I chondrules. Mean diameters of chondrules range from 0.22 to 1.05 mm for Karoonda (CK4) and Tnz 057 (CK4), respectively. Up to ~60% of chondrules in CK3-4 are surrounded by igneous rims (from ~20 μm to 2 mm width). Zoned olivines were found in unequilibrated chondrules from DaG 431 (CK3-an), NWA 4724 (CK3.8), NWA 4423 (CK3.9), and Tnz 057 (CK4). We modeled Fe/Mg interdiffusion profiles measured in zoned olivines to evaluate the peak metamorphic temperatures and time scales of the CK parent body metamorphism, and proposed a two-stage diffusion process in order to account for the position of inflection points situated within chondrules. Time scales inferred from Fe/Mg interdiffusion in olivine from unequilibrated chondrules are on the order of tens to a hundred thousand years (from 50 to 70,000 years for peak metamorphic temperatures of 1140 and 920 K, respectively). These durations are longer than what is commonly accepted for shock metamorphism and shorter than what is required for nuclide decay. Using the concept of a continuous CV-CK metamorphic series, which is reinforced by this study, we estimated peak metamorphic temperatures chondrites considering a duration of 70,000 years.

  9. Weakly shocked and deformed CM microxenoliths in the Pułtusk H chondrite

    Science.gov (United States)

    KrzesińSka, Agata; Fritz, JöRg

    2014-04-01

    The Pułtusk meteorite is a brecciated H4-5 chondrite cut by darkened cataclastic zones. Within the breccia, relict type IA, IB, and IIA chondrules, and microxenoliths of carbonaceous CM chondrite lithology occur. This is the first description of foreign clasts in the Pułtusk meteorite. The matrix of the xenoliths was identified by usage of microprobe and Raman spectroscopic analyses. Raman spectra show distinct bands related to the presence of slightly ordered carbonaceous matter at approximately 1320 and 1580-1584 cm-1. Bands related to serpentine group minerals are also visible, especially a peak at 692 cm-1 and moreover other weak bands are interpreted as evidence for tochilinite. We decipher the metamorphic and deformational history of the xenoliths. They experienced aqueous alteration before being incorporated into the unaltered and well-equilibrated parent rock of the Pułtusk chondrite. The xenoliths are weakly shocked as indicated by defects in the crystal structure of silicates and carbonates, but hydrated minerals (serpentine and tochilinite) are still present in the matrix. The carbonaceous matter within the clasts' matrix displays first order D and G Raman bands that suggests it is only slightly ordered as a result of mild thermal processing. Distinct shear bands are present in both the xenoliths and the surrounding rock, which testifies that the xenoliths were affected by a deformational event along with host rock. The host rock was brittly deformed, but the clasts experienced more ductile deformation revealed by semibrittle faulting of minerals, kinking of the tochilinite-cronstedtite matrix, and injections of xenolithic material into the adjacent breccia. We argue that both processes, the high strain-rate shear deformation and the incorporation of the xenoliths into the host Pułtusk breccia, could have been impact-related. The Pułtusk xenoliths are, thus, rather spalled collisional fragments, than trapped fossil micrometeorites.

  10. Mechanisms of ringwoodite formation in shocked meteorites: Evidence from L5 chondrite Dhofar 1970

    Science.gov (United States)

    Walton, Erin L.; McCarthy, Sabrina

    2017-04-01

    The formation of the high-pressure compositional equivalents of olivine and pyroxene has been well-documented within and surrounding shock-induced veins in chondritic meteorites, formed by crystallization from a liquid- or solid-state phase transformation. Typically polycrystalline ringwoodite grains have a narrow range of compositions that overlap with those of their olivine precursors, whereas the formation of iron-enriched ringwoodite has been documented from only a handful of meteorites. Here, we report backscattered electron images, quantitative wavelength-dispersive spectrometry (WDS) analyses, qualitative WDS elemental X-ray maps, and micro-Raman spectra that reveal the presence of Fe-rich ringwoodite (Fa44-63) as fine-grained (500 nm), polycrystalline rims on olivine (Fa24-25) wall rock and as clasts engulfed by shock melt in a previously unstudied L5 chondrite, Dhofar 1970. Crystallization of majorite + magnesiowüstite in the vein interior and metastable mineral assemblages within 35 μm of the vein margin attest to rapid crystallization of a superheated shock melt (>2300 K) from 20-25 GPa to ambient pressure and temperature. The texture and composition of bright polycrystalline ringwoodite rims (Fa44-63; MnO 0.01-0.08 wt%) surrounding dark polycrystalline olivine (Fa8-14; MnO 0.56-0.65 wt%) implies a solid-state transformation mechanism in which Fe was preferentially partitioned to ringwoodite. The spatial association between ringwoodite and shock melt suggests that the rapidly fluctuating thermal regimes experienced by chondritic minerals in contact with shock melt are necessary to both drive phase transformation but also to prevent back-transformation.

  11. Nebular dead zone effects on the D/H ratio in chondrites and comets

    Science.gov (United States)

    Ali-Dib, Mohamad; Martin, R. G.; Petit, J.-M.; Mousis, O.; Vernazza, P.; Lunine, J. I.

    2015-11-01

    Comets and chondrites show non-monotonic behaviour of their Deuterium to Hydrogen (D/H) ratio as a function of their formation location from the Sun. This is difficult to explain with a classical protoplanetary disk model that has a decreasing temperature structure with radius from the Sun.We want to understand if a protoplanetary disc with a dead zone, a region of zero or low turbulence, can explain the measured D/H values in comets and chondrites. We use time snapshots of a vertically layered disk model with turbulent surface layers and a dead zone at the midplane. The disc has a non-monotonic temperature structure due to increased heating from self-gravity in the outer parts of the dead zone. We couple this to a D/H ratio evolution model in order to quantify the effect of such thermal profiles on D/H enrichment in the nebula.We find that the local temperature peak in the disk can explain the diversity in the D/H ratios of different chondritic families. This disk temperature profile leads to a non-monotonic D/H enrichment evolution, allowing these families to acquire their different D/H values while forming in close proximity. The formation order we infer for these families is compatible with that inferred from their water abundances. However, we find that even for very young disks, the thermal profile reversal is too close to the Sun to be relevant for comets.[1] Ali-Dib, M., Martin, R. G., Petit, J.-M., Mousis, O., Vernazza, P., and Lunine, J. I. (2015, in press A&A). arXiv:1508.00263.

  12. High-pressure phases in shock-induced melt of the unique highly shocked LL6 chondrite Northwest Africa 757

    Science.gov (United States)

    Hu, Jinping; Sharp, Thomas G.

    2016-07-01

    Northwest Africa 757 is unique in the LL chondrite group because of its abundant shock-induced melt and high-pressure minerals. Olivine fragments entrained in the melt transform partially and completely into ringwoodite. Plagioclase and Ca-phosphate transform to maskelynite, lingunite, and tuite. Two distinct shock-melt crystallization assemblages were studied by FIB-TEM analysis. The first melt assemblage, which includes majoritic garnet, ringwoodite plus magnetite-magnesiowüstite, crystallized at pressures of 20-25 GPa. The other melt assemblage, which consists of clinopyroxene and wadsleyite, solidified at ~15 GPa, suggesting a second veining event under lower pressure conditions. These shock features are similar to those in S6 L chondrites and indicate that NWA 757 experienced an intense impact event, comparable to the impact event that disrupted the L chondrite parent body at 470 Ma.

  13. The Maryville meteorite - A 1983 fall of an L6 chondrite

    Science.gov (United States)

    Shervais, J. W.; Taylor, L. A.; Cirlin, E.-H.; Jarosewich, E.; Laul, J. C.

    1986-01-01

    The Maryville chondrite fell on January 28, 1983 in eastern Tennessee. Compositions of olivine (Fa 24.5), orthopyroxene (Fs 20.8), plagioclase (An 10.6), along with the bulk composition and siderophile concentrations, indicate L-group classification. The presence of highly equilibrated minerals, strongly recrystallized matrix, and the development of large, clear plagioclase grains suggest petrologic type 6 classification. Subsequent to metamorphism the meteorite was subjected to high transient pressures that converted some feldspar to glass, deformed the silicates, and caused small amounts of melting to occur. The effects of this shock event correspond to shock facies 'd' or 'e'.

  14. The magnetic effects of brecciation and shock in meteorites. I - The LL-chondrites

    Science.gov (United States)

    Brecher, A.; Stein, J.; Fuhrman, M.

    1977-01-01

    The magnetic behavior of eight LL chondrites is analyzed in detail, and some implications for their modes of formation and evolutionary history are examined. Petrographic features of the specimens are described, and their initial magnetic characteristics are discussed. The demagnetization behavior of the initial magnetization is investigated along with the saturation remanence behavior and paleomagnetic-field intensities. The results indicate that a magnetic field of 0.01 to 0.1 Oe may have been present during postimpact cooling and that severe shock metamorphism may have given rise to the observed magnetic moments and behavior, even in the absence of ambient magnetic fields.

  15. Fluid evolution in CM carbonaceous chondrites tracked through the oxygen isotopic compositions of carbonates

    Science.gov (United States)

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

    2017-05-01

    The oxygen isotopic compositions of calcite grains in four CM carbonaceous chondrites have been determined by NanoSIMS, and results reveal that aqueous solutions evolved in a similar manner between parent body regions with different intensities of aqueous alteration. Two types of calcite were identified in Murchison, Mighei, Cold Bokkeveld and LaPaz Icefield 031166 by differences in their petrographic properties and oxygen isotope values. Type 1 calcite occurs as small equant grains that formed by filling of pore spaces in meteorite matrices during the earliest stages of alteration. On average, the type 1 grains have a δ18O of ∼32-36‰ (VSMOW), and Δ17O of between ∼2‰ and -1‰. Most grains of type 2 calcite precipitated after type 1. They contain micropores and inclusions, and have replaced ferromagnesian silicate minerals. Type 2 calcite has an average δ18O of ∼21-24‰ (VSMOW) and a Δ17O of between ∼-1‰ and -3‰. Such consistent isotopic differences between the two calcite types show that they formed in discrete episodes and from solutions whose δ18O and δ17O values had changed by reaction with parent body silicates, as predicted by the closed-system model for aqueous alteration. Temperatures are likely to have increased over the timespan of calcite precipitation, possibly owing to exothermic serpentinisation. The most highly altered CM chondrites commonly contain dolomite in addition to calcite. Dolomite grains in two previously studied CM chondrites have a narrow range in δ18O (∼25-29‰ VSMOW), with Δ17O ∼-1‰ to -3‰. These grains are likely to have precipitated between types 1 and 2 calcite, and in response to a transient heating event and/or a brief increase in fluid magnesium/calcium ratios. In spite of this evidence for localised excursions in temperature and/or solution chemistry, the carbonate oxygen isotope record shows that fluid evolution was comparable between many parent body regions. The CM carbonaceous chondrites

  16. Ridge regression estimator: combining unbiased and ordinary ridge regression methods of estimation

    Directory of Open Access Journals (Sweden)

    Sharad Damodar Gore

    2009-10-01

    Full Text Available Statistical literature has several methods for coping with multicollinearity. This paper introduces a new shrinkage estimator, called modified unbiased ridge (MUR. This estimator is obtained from unbiased ridge regression (URR in the same way that ordinary ridge regression (ORR is obtained from ordinary least squares (OLS. Properties of MUR are derived. Results on its matrix mean squared error (MMSE are obtained. MUR is compared with ORR and URR in terms of MMSE. These results are illustrated with an example based on data generated by Hoerl and Kennard (1975.

  17. Conversion of emergency lanes to ordinary lanes for use under peak load

    DEFF Research Database (Denmark)

    Jensen, Peder; Kjærbo, Kasper Lidén

    1999-01-01

    The paper explores the potential for the use of freeway emergency lanes for use as ordinary lanes during rush hours. A simulation model of the orbital motorway around Copenhagen is used to show that such installations have the potential to reduce congestion significantly.......The paper explores the potential for the use of freeway emergency lanes for use as ordinary lanes during rush hours. A simulation model of the orbital motorway around Copenhagen is used to show that such installations have the potential to reduce congestion significantly....

  18. Generation and Identification of Ordinary Differential Equations of Maximal Symmetry Algebra

    Directory of Open Access Journals (Sweden)

    J. C. Ndogmo

    2016-01-01

    Full Text Available An effective method for generating linear ordinary differential equations of maximal symmetry in their most general form is found, and an explicit expression for the point transformation reducing the equation to its canonical form is obtained. New expressions for the general solution are also found, as well as several identification and other results and a direct proof of the fact that a linear ordinary differential equation is iterative if and only if it is reducible to the canonical form by a point transformation. New classes of solvable equations parameterized by an arbitrary function are also found, together with simple algebraic expressions for the corresponding general solution.

  19. Differential equation analysis in biomedical science and engineering ordinary differential equation applications with R

    CERN Document Server

    Schiesser, William E

    2014-01-01

    Features a solid foundation of mathematical and computational tools to formulate and solve real-world ODE problems across various fields With a step-by-step approach to solving ordinary differential equations (ODEs), Differential Equation Analysis in Biomedical Science and Engineering: Ordinary Differential Equation Applications with R successfully applies computational techniques for solving real-worldODE problems that are found in a variety of fields, including chemistry, physics, biology,and physiology. The book provides readers with the necessary knowledge to reproduce andextend the comp

  20. First-episode psychosis patients recruited into treatment via early detection teams versus ordinary pathways

    DEFF Research Database (Denmark)

    Johannessen, Jan O; Friis, Svein; Joa, Inge

    2007-01-01

    Within an early detection sector, to compare the 1- and 2-year course and outcome of first-episode psychosis patients coming into the treatment system via active outreach detection teams (DTs) versus those achieving help via ordinary referral channels (not-DT).......Within an early detection sector, to compare the 1- and 2-year course and outcome of first-episode psychosis patients coming into the treatment system via active outreach detection teams (DTs) versus those achieving help via ordinary referral channels (not-DT)....

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

    Science.gov (United States)

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

    2014-01-01

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

  2. Cosmogenic Radionuclides in Hot Desert Chondrites with Low C-14 Activities: A Progress Report

    Science.gov (United States)

    Welten, Kees; Nishiizumi, Kunihiko; Caffee, Marc W.

    1999-01-01

    Terrestrial ages of meteorites from hot deserts provide an important tool to estimate meteorite fluxes to the Earth. Most desert meteorites have terrestrial ages less than 40 ky, but a few achondrites from the Sahara region were recently shown to have significantly higher ages, up to approx. 100 ky. In general, C-14 (half-life = 5730 y) is the most suited radionuclide to determine terrestrial ages for desert meteorites. However for meteorites with ages greater than 35 ky, the concentration of cosmogenic C-14 has decreased to a level at which it becomes difficult to distinguish between cosmogenic C-14 and terrestrial contamination. These meteorites may therefore be much older than 35 ky. We selected chondrites with low C-14 activities (less than or equal to 2 dpm/kg) for measurements of the concentrations of cosmogenic Cl-36 (half-life= 3.01 x 10 (exp 5) y) and Ca-41 (half-life= 1.04 x 10 (exp 5) y) in the metal phase. Since the ratio of Ca-14/Cl-36 in the metal phase of chondrites is relatively constant and well known, the measured ratio is a direct measure of the terrestrial age. A major problem is that most or sometimes all of the metal in these old "hot desert" meteorites has been oxidized to hydrated Fe-Ni-oxides. Therefore, we also measured the concentrations of Be-10, Al-26 and Cl-36 in the stony phase in order to constrain the terrestrial age as much as possible.

  3. Cosmogenic Radionuclides in Hot Desert Chondrites With Low C-14 Activities

    Science.gov (United States)

    Welten, K. C.; Nishiizumi, K.; Caffee, M. W.

    2000-01-01

    Terrestrial ages of meteorites from hot deserts provide an important tool to estimate meteorite fluxes to the Earth. Most desert meteorites have terrestrial ages less than 40 ky, but a few achondrites from the Sahara region were recently shown to have significantly higher ages, up to approx.100 ky. In general, C-14 (half-life = 5730 y) is the most suited radionuclide to determine terrestrial ages for desert meteorites. However for meteorites with ages >35 ky, the concentration of cosmogenic C-14 has decreased to a level at which it becomes difficult to distinguish between cosmogenic C-14 and terrestrial contamination. These meteorites may therefore be much older than 35 ky. We selected chondrites with low C-14 activities (less than or equal to 2 dpm/kg) for measurements of the concentrations of cosmogenic Cl-36 (half-life= 3.01 x 105 y) and Ca-41 (half-life= 1.04 x 105 y) in the metal phase. Since the ratio of Ca-41/Cl-36 in the metal phase of chondrites is relatively constant and well known, the measured ratio is a direct measure of the terrestrial age]. A major problem is that most or sometimes all. of the metal in these old "hot desert" meteorites has been oxidized to hydrated Fe-Ni-oxides. Therefore, we also measured the concentrations of Be-10, Al-26 and Cl-36 in the stony phase in order to constrain the terrestrial age as much as possible.

  4. Particle shape and magnetization of chondrite meteorites, lunar samples, and impactites

    Science.gov (United States)

    Wasilewski, P.

    1972-01-01

    Extra terrestrial materials, certain materials which have their origin at the earth's surface due to meteoritic impact, or under highly reducing conditions, such as in the case of basaltic flows in contact with coal beds or serpentenites, all contain Fe and FeNi phases with high magnetization values and spherical shape. Normally, the demagnetizing field (H sub D = NI sub S: where N is the demagnetizing factor and I is the saturation magnetization) is corrected for. In disperse systems, such as most natural materials, the particle shape effects are analyzed in terms of the saturation fields, Hs = H sub D = NI sub S and the magnetization differences (Delta I sub S). Discrete size modes of superparamagnetic (SP), multidomain (MD), and single domain (SD) particles result in reduced coercive force (Hc), increase in the value R sub H (ratio of remanent coercive force, H sub R, to H sub C), and decrease in the value R sub I (ratio of remanent magnetization, I sub R, to saturation magnetization, T sub S). The main distinctions between the various natural materials can be made by this approach. Hysteresis loops for terrestrial basalts, Fe and Ni rods and spheres, chondrite meteorites, lunar samples, impactites, and chondritic fusion crust are presented.

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

    Science.gov (United States)

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

    2015-01-01

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

  6. Non-chondritic iron isotope ratios in planetary mantles as a result of core formation

    Science.gov (United States)

    Elardo, Stephen M.; Shahar, Anat

    2017-02-01

    Information about the materials and conditions involved in planetary formation and differentiation in the early Solar System is recorded in iron isotope ratios. Samples from Earth, the Moon, Mars and the asteroid Vesta reveal significant variations in iron isotope ratios, but the sources of these variations remain uncertain. Here we present experiments that demonstrate that under the conditions of planetary core formation expected for the Moon, Mars and Vesta, iron isotopes fractionate between metal and silicate due to the presence of nickel, and enrich the bodies' mantles in isotopically light iron. However, the effect of nickel diminishes at higher temperatures: under conditions expected for Earth's core formation, we infer little fractionation of iron isotopes. From our experimental results and existing conceptual models of magma ocean crystallization and mantle partial melting, we find that nickel-induced fractionation can explain iron isotope variability found in planetary samples without invoking nebular or accretionary processes. We suggest that near-chondritic iron isotope ratios of basalts from Mars and Vesta, as well as the most primitive lunar basalts, were achieved by melting of isotopically light mantles, whereas the heavy iron isotope ratios of terrestrial ocean floor basalts are the result of melting of near-chondritic Earth mantle.

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

    Science.gov (United States)

    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.

  8. New Nd-142 Evidence for a Non-Chondritic Composition of the Moon

    Science.gov (United States)

    Nyquist, L.; Touboul, M.; Kleine, T.; Bourdon, B.; Shih, C.Y.

    2009-01-01

    The coupled Sm-147,146-Nd-143,142 systematics of lunar samples has been extensively studied for estimating the timescale of lunar differentiation. The published datasets yield consistent ages for Nd isotopic closure within the lunar mantle of approx.200 Myr after CAI formation. Although this time constraint is consistent with estimates derived from Hf-W chronometry of the Moon (>60 Myr after CAI formation), there is debate as to whether this age has chronological significance. Furthermore, there are discrepancies regarding the Nd isotope composition of the bulk Moon. Rankenburg et al. obtained a epsilon Nd-142 vs. Sm-147/Nd-144 correlation for lunar samples passing though the chondritic reference value (Sm-147/Nd-144 = 0.1967, epsilon Nd-142 = -0.21), suggesting that the Moon has a chondritic bulk composition. In contrast, the other datasets define a correlation line that passes approx.10-20 ppm above, suggesting that the Moon has a superchondritic Sm-147/Nd-144 (approx.0.206), close to that of the early depleted Earth (EDM). We present new Sm-Nd data for a high-Ti mare basalt (70135), two low-Ti mare basalt (LAP 02205 and MIL 05035) and a KREEPy low-Ti mare basalt (NWA 2977). These data are used to evaluate the significance of the Sm-Nd systematics for constraining the timescale of lunar differentiation and the bulk Nd isotope composition of the Moon.

  9. Probing the early stages of shock-induced chondritic meteorite formation at the mesoscale

    Science.gov (United States)

    Rutherford, Michael E.; Chapman, David J.; Derrick, James G.; Patten, Jack R. W.; Bland, Philip A.; Rack, Alexander; Collins, Gareth S.; Eakins, Daniel E.

    2017-05-01

    Chondritic meteorites are fragments of asteroids, the building blocks of planets, that retain a record of primordial processes. Important in their early evolution was impact-driven lithification, where a porous mixture of millimetre-scale chondrule inclusions and sub-micrometre dust was compacted into rock. In this Article, the shock compression of analogue precursor chondrite material was probed using state of the art dynamic X-ray radiography. Spatially-resolved shock and particle velocities, and shock front thicknesses were extracted directly from the radiographs, representing a greatly enhanced scope of data than could be measured in surface-based studies. A statistical interpretation of the measured velocities showed that mean values were in good agreement with those predicted using continuum-level modelling and mixture theory. However, the distribution and evolution of wave velocities and wavefront thicknesses were observed to be intimately linked to the mesoscopic structure of the sample. This Article provides the first detailed experimental insight into the distribution of extreme states within a shocked powder mixture, and represents the first mesoscopic validation of leading theories concerning the variation in extreme pressure-temperature states during the formation of primordial planetary bodies.

  10. Early history of Earth's crust-mantle system inferred from hafnium isotopes in chondrites

    DEFF Research Database (Denmark)

    Bizzarro, Martin; Haack, Henning; Rosing, M.

    2003-01-01

    The Lu to Hf decay series has been widely used to understand the nature of Earth's early crust-mantle system. The interpretation, however, of Lu-Hf isotope data requires accurate knowledge of the radioactive decay constant of Lu (¿176), as well as bulk-Earth reference parameters. A recent...... calibration of the ¿176 value calls for the presence of highly unradiogenic hafnium in terrestrial zircons with ages greater than 3.9 Gyr, implying widespread continental crust extraction from an isotopically enriched mantle source more than 4.3 Gyr ago, but does not provide evidence for a complementary...... depleted mantle reservoir. Here we report Lu-Hf isotope measurements of different Solar System objects including chondrites and basaltic eucrites. The chondrites define a Lu-Hf isochron with an initial Hf/Hf ratio of 0.279628 ± 0.000047, corresponding to ¿176 = 1.983 ± 0.033 x 10yr using an age of 4.56 Gyr...

  11. Second derivative multistep method for solving first-order ordinary differential equations

    Science.gov (United States)

    Turki, Mohammed Yousif; Ismail, Fudziah; Senu, Norazak; Ibrahim, Zarina Bibi

    2016-06-01

    In this paper, a new second derivative multistep method was constructed to solve first order ordinary differential equations (ODEs). In particular, we used the new method as a corrector method and 5-steps Adam's Bashforth method as a predictor method to solve first order (ODEs). Numerical results were compared with the existing methods which clearly showed the efficiency of the new method.

  12. Ordinary legal remedies according to provisions of legislation from 1853 and 1860

    Directory of Open Access Journals (Sweden)

    Kulauzov Maša M.

    2016-01-01

    Full Text Available The article sheds light on provisions of Codes of Civil Procedure of 1853 and 1860 concerning ordinary legal remedies. As this matter was codified for the first time, a necessity of amending and supplementing some provisions soon emerged. Those amendments and supplements, along with original provisions were examined in this paper. The author also deals with regulations on jurisdiction of Court of Appeal, Court of Cassation and Supreme court. Types and categories of ordinary legal remedies were scrutinized, as well as strict time limits within one should lodge an appeal and proper grounds for making an appeal. The author also responds to questions under which circumstances are ordinary legal remedies allowed, and what types of decisions a higher court can make after reviewing the correctness and reasonableness of a decision issued by a lower court. Shortly after enactment of the Code of 1853 it appeared that judicial procedure is too complicated, expensive and ineffective due to too many legal remedies and legal jurisdictions. That is the reason why the Supreme court as the highest court within the hierarchy of legal jurisdictions and as final court of appeal was abolished in 1860, when new Code of Civil Procedure had been passed. New codification envisaged Court of Appeal as second instance court and, at the same time, court of last resort. Regarding legal remedies, Code of 1860 introduced appeal as sole ordinary legal remedy.

  13. [Review of: K.-S. Taussig Ordinary genomes: science, citizenship, and genetic identities

    NARCIS (Netherlands)

    Kato, M.

    2010-01-01

    Ordinary Genomes is an ethnography of clinical genetics practice in the Netherlands, written by US anthropologist Karen-Sue Taussig. By looking at the case of the Netherlands, this book aims to illuminate the way specific scientific knowledge - in this case genomics - which is generally presumed to

  14. 75 FR 43840 - Inflation Adjustment of the Ordinary Maximum and Aggravated Maximum Civil Monetary Penalties for...

    Science.gov (United States)

    2010-07-27

    ... TRANSPORTATION Federal Railroad Administration 49 CFR Part 209 RIN 2130-ZA03 Inflation Adjustment of the Ordinary... Inflation Adjustment Act of 1990 as amended by the Debt Collection Improvement Act of 1996. DATES: Effective...-493-6027), [email protected] . SUPPLEMENTARY INFORMATION: The Federal Civil Penalties Inflation...

  15. A block Krylov subspace time-exact solution method for linear ordinary differential equation systems

    NARCIS (Netherlands)

    Bochev, Mikhail A.

    2013-01-01

    We propose a time-exact Krylov-subspace-based method for solving linear ordinary differential equation systems of the form $y'=-Ay+g(t)$ and $y"=-Ay+g(t)$, where $y(t)$ is the unknown function. The method consists of two stages. The first stage is an accurate piecewise polynomial approximation of

  16. First Order Linear Homogeneous Fuzzy Ordinary Differential Equation Based on Lagrange Multiplier Method

    Directory of Open Access Journals (Sweden)

    Sankar Prasad Mondal

    2013-11-01

    Full Text Available In this paper the First Order Linear Fuzzy Ordinary Differential Equations are described. Here coefficients and /or initial condition of said differential equation are taken as the Generalized Triangular Fuzzy Numbers (GTFNs.The solution procedure of this Fuzzy Differential Equation is developed by Lagrange Multiplier Method. An imprecise barometric pressure problem is described.

  17. 3D Laser Scanning Assisted by Ordinary Plane Mirror for Non-direct Viewing Area

    Directory of Open Access Journals (Sweden)

    ZHANG Fan

    2017-12-01

    Full Text Available Terrestrial 3D laser scanning is one of principal methods to get the geometric information of object surface,and the integrity of the scanned object is a basic requirement in data acquisition. In order to solve the missing point cloud problem due to the scanning dead angle caused by confined working space,this paper proposes a method using ordinary plane mirror to obtain laser scanning data for non-direct viewing area according to the plane mirror reflection principle,analyzes the influence mechanism of the ordinary plane mirror on the propagation path and distance of laser beam,deduces the coordinate equation of the object point corresponding to the image point reflected by ordinary plane mirror in laser scanning. Given the laser scanning characteristic,this paper introduces a mirror reflection system included target balls and ordinary plane mirror,and expounds the system construction,system calibration and constructing method of system coordinate system. The feasibility and precision of the method are verified by experiments.

  18. Proceedings of the Nordic society for radiation protection 12. ordinary meeting

    DEFF Research Database (Denmark)

    The key themes of teh 12th ordinary general meeting of the Nordic Society for Radiation Protection were: RADIATION - ENVIRONMENT - INFORMATION. A number of outstanding international experts accepted to contribute on the meetings first day with invited presentations, which focussed on these themes...

  19. A collection of test problems for ordinary differential equation solvers which have provisions for rootfinding

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, S.

    1987-08-01

    Several popular ordinary differential equation (ode) solvers contain provisions for locating roots of functions which depend on the solution of the ode. A collection of problems for testing such solvers is described in this report. In addition to several well-known problems, the collection contains other interesting problems which have not previously appeared in the literature.

  20. Linear Ordinary Differential Equations with Constant Coefficients. Revisiting the Impulsive Response Method Using Factorization

    Science.gov (United States)

    Camporesi, Roberto

    2011-01-01

    We present an approach to the impulsive response method for solving linear constant-coefficient ordinary differential equations based on the factorization of the differential operator. The approach is elementary, we only assume a basic knowledge of calculus and linear algebra. In particular, we avoid the use of distribution theory, as well as of…

  1. Third-order ordinary differential equations Y”' = f(x, y, y'', y′”) with ...

    African Journals Online (AJOL)

    Third-order ordinary differential equations Y”' = f(x, y, y'', y′”) with maximal symmetry group. ... symmetry algebra. Mathematics Subject Classication (2010): 34A05, 34A25, 53A55, 76M60. Key words: Linearization, third order ODEs, point transformation, contact transformation, Lie symmetries, relative differential invariants.

  2. Extending the Constant Coefficient Solution Technique to Variable Coefficient Ordinary Differential Equations

    Science.gov (United States)

    Mohammed, Ahmed; Zeleke, Aklilu

    2015-01-01

    We introduce a class of second-order ordinary differential equations (ODEs) with variable coefficients whose closed-form solutions can be obtained by the same method used to solve ODEs with constant coefficients. General solutions for the homogeneous case are discussed.

  3. Identifying and Exploring Relationships between Contextual Situations and Ordinary Differential Equations

    Science.gov (United States)

    Camacho-Machín, M.; Guerrero-Ortiz, C.

    2015-01-01

    The aim of this paper is to present and discuss some of the evidence regarding the resources that students use when they establish relationships between a contextual situation and an ordinary differential equation (ODE). We present research results obtained from work by seven students in a graduate level course in mathematics education, where they…

  4. A Simple Method to Find out when an Ordinary Differential Equation Is Separable

    Science.gov (United States)

    Cid, Jose Angel

    2009-01-01

    We present an alternative method to that of Scott (D. Scott, "When is an ordinary differential equation separable?", "Amer. Math. Monthly" 92 (1985), pp. 422-423) to teach the students how to discover whether a differential equation y[prime] = f(x,y) is separable or not when the nonlinearity f(x, y) is not explicitly factorized. Our approach is…

  5. Lie symmetries of systems of second-order linear ordinary differential equations with constant coefficients

    Science.gov (United States)

    Boyko, Vyacheslav M.; Popovych, Roman O.; Shapoval, Nataliya M.

    2013-01-01

    Lie symmetries of systems of second-order linear ordinary differential equations with constant coefficients are exhaustively described over both the complex and real fields. The exact lower and upper bounds for the dimensions of the maximal Lie invariance algebras possessed by such systems are obtained using an effective algebraic approach. PMID:23564972

  6. Constructive Development of the Solutions of Linear Equations in Introductory Ordinary Differential Equations

    Science.gov (United States)

    Mallet, D. G.; McCue, S. W.

    2009-01-01

    The solution of linear ordinary differential equations (ODEs) is commonly taught in first-year undergraduate mathematics classrooms, but the understanding of the concept of a solution is not always grasped by students until much later. Recognizing what it is to be a solution of a linear ODE and how to postulate such solutions, without resorting to…

  7. Student Interpretations of the Terms in First-Order Ordinary Differential Equations in Modelling Contexts

    Science.gov (United States)

    Rowland, David R.; Jovanoski, Zlatko

    2004-01-01

    A study of first-year undergraduate students' interpretational difficulties with first-order ordinary differential equations (ODEs) in modelling contexts was conducted using a diagnostic quiz, exam questions and follow-up interviews. These investigations indicate that when thinking about such ODEs, many students muddle thinking about the function…

  8. Digital urbanisms : Exploring the spectacular, ordinary and contested facets of the media city

    NARCIS (Netherlands)

    Vuolteenaho, Jani; Leurs, K.H.A.|info:eu-repo/dai/nl/343295334; Sumiala, Johanna

    2015-01-01

    This introductory review article develops an analytic-conceptual distinction between spectacular, ordinary and contested facets of the present-day digitized urban condition. We reject a scholarly techno-optimism versus techno-pessimism dichotomy and argue that this triadic conceptualization can pave

  9. On periodic bounded and unbounded solutions of second order nonlinear ordinary differential equations

    Czech Academy of Sciences Publication Activity Database

    Lomtatidze, Alexander

    2017-01-01

    Roč. 24, č. 2 (2017), s. 241-263 ISSN 1072-947X Institutional support: RVO:67985840 Keywords : nonlinear ordinary differential equations * periodic boundary value problem * solvability Subject RIV: BA - General Mathematics Impact factor: 0.290, year: 2016 https://www.degruyter.com/view/j/gmj.2017.24.issue-2/gmj-2017-0009/gmj-2017-0009. xml

  10. Solving Second-Order Ordinary Differential Equations without Using Complex Numbers

    Science.gov (United States)

    Kougias, Ioannis E.

    2009-01-01

    Ordinary differential equations (ODEs) is a subject with a wide range of applications and the need of introducing it to students often arises in the last year of high school, as well as in the early stages of tertiary education. The usual methods of solving second-order ODEs with constant coefficients, among others, rely upon the use of complex…

  11. Comparative numerical solutions of stiff Ordinary differential equations using magnus series expansion method

    Directory of Open Access Journals (Sweden)

    SURE KÖME

    2014-12-01

    Full Text Available In this paper, we investigated the effect of Magnus Series Expansion Method on homogeneous stiff ordinary differential equations with different stiffness ratios. A Magnus type integrator is used to obtain numerical solutions of two different examples of stiff problems and exact and approximate results are tabulated. Furthermore, absolute error graphics are demonstrated in detail.

  12. An algorithm for solving initial value problems of third order ordinary ...

    African Journals Online (AJOL)

    We propose an implicit multi-step method for the solution of initial value problems (IVPs) of third order ordinary differential equations (ODE) which does not require reducing the ODE to first order before solving. The development of the method is based on collocation of the differential system and interpolation of the ...

  13. From Sharing to Experimenting: How Mobile Technologies Are Helping Ordinary Citizens Regain Their Positions as Scientists

    Science.gov (United States)

    Devisch, Oswald; Veestraeten, Daniel

    2013-01-01

    Citizen science is a term used to describe the engagement of ordinary citizens in scientific tasks like observation, measurement, and computation. A series of technological innovations, such as the Internet, the upgrade of mobile phones from communication devices to networked mobile personal measurement devices, and the introduction of…

  14. On Fits of Seasonal Data by the Ordinary Least Square Method

    CERN Document Server

    Rotundo, G; Herteli, C; Ileanu, B V

    2016-01-01

    Following Shimura et al. pioneering paper (1981) on "Geographical and secular changes in the seasonal distribution of births", much data has been reported by seasonal effects time series. We discuss how one can be misled in testing Linear Regression Models by an Ordinary Least Square method.

  15. Crowdsourcing ideas : Involving ordinary users in the ideation phase of new product development

    NARCIS (Netherlands)

    Schemmann, Brita; Herrmann, Andrea M.; Chappin, Maryse M H; Heimeriks, Gaston J.

    2016-01-01

    The different roles of users in new product development (NPD) have been extensively described. Currently online idea crowdsourcing, via long-term open idea calls, is increasingly being used by companies to collect new product ideas from ordinary users. Such open idea calls can result in thousands of

  16. 29th June 2017 – Ordinary General Assembly of the Staff Association!

    CERN Multimedia

    Staff Association

    2017-01-01

    In the first semester of each year, the Staff Association (SA) invites its members to attend and participate in the Ordinary General Assembly (OGA). This year the OGA will be held on Thursday, 29 June 2017 from 15.30 to 17.30, Main Auditorium, Meyrin (500-1-001). During the Ordinary General Assembly, the activity and financial reports of the SA are presented and submitted for approval to the members. This is the occasion to get a global view on the activities of the SA, its management, and an opportunity to express your opinion, particularly by taking part in votes. Other items are listed on the agenda, as proposed by the Staff Council. Who can vote? Ordinary members (MPE) of the SA can take part in all votes. Associated members (MPA) of the SA and/or affiliated pensioners have a right to vote on those topics that are of direct interest to them. Who can give their opinion, and how? The Ordinary General Assembly is also the opportunity for members of the SA to express themselves through the addition of disc...

  17. Ordinary Level as Results Predictors of Students' Academic Performance in Chemistry in Nigerian Universities

    Science.gov (United States)

    Kolawole, E. B.; Oginni, O. I.; Fayomi, E. O.

    2011-01-01

    This paper examined ordinary level result as predictors of students' academic performance in chemistry in South-west Nigeria universities. It also examined the relationship between the academic performance of students in each level of the university examinations and their corresponding secondary school certificates examination. The sample of the…

  18. An Ordinary Level as Predictors of Students' Academic Performance in Chemistry in Nigerian Universities

    Science.gov (United States)

    Kolawole, E. B.; Oginni, O. I.; Fayomi, E. O.

    2011-01-01

    This paper examined an ordinary level as predictors of students' academic performance in chemistry in South-west Nigeria universities. It also revealed the relationship between the academic performance of students in each level of the university examinations and their corresponding secondary school certificates examination. The sample of the study…

  19. Mundrabilla 012: A New CV2(?) Chondrite Find from the Southwest Australia

    Science.gov (United States)

    Ulff-Moller, F.; Rasmussen, K. L.; Grundvig, S.

    1993-07-01

    A carbonaceous chondrite with a total mass of 30.6 g was found in the Mundrabilla area on the Nullarbor Plains in Southwest Australia in 1992. The meteorite contains more than 30 vol% chondrules and is heavily altered. No metal or glassy chondrule mesostasis are preserved. The chondrules vary from spheres with 1 mm diameter to ellipsoids up to 2 mm long with an aspect ratio of 3 that seems to be aligned. The chondrule textures are typically olivine-microporphyritic; one "barred olivine" chondrule contains rosy spinel. Spherical metal grains (now iron-oxide pseudomorphs) are frequently seen at chondrule margins. The olivines have highly magnesian cores (Fa 0.3-6) whereas margins and narrow zones along fractures are strongly Fe-enriched (Fa 20). The altered mesostasis retained its primary chemistry in part, but shows strong local enrichment of K. Hydrothermal alteration has turned some chondrules into "ghosts" that are just barely recognizable. The fine-grained matrix is semitransparent with a reddish-brown color and consists of sheet silicates. The matrix contains diffuse, recrystallized patches that consist of iron-rich olivine (Fa 44), diopside, and calcium carbonate. Iron-sulphide-rich domains are typically associated with magnetite. High-T(?) Inclusions: We found a single, 20-my-sized, green, transparent spinel grain with an irregular surface in the matrix. In addition, we found a 0.5-mm kidney-shaped inclusion with a submicroscopic Ca-Al-silicate-rich matrix with tiny, dispersed grains of ilmenite (hem 8.5). Low totals of the microprobe analyses suggest that the matrix contains carbonates or hydroxides. Secondary Processes: Our observations indicate that the chondrite parent body underwent a long period of pervasive hydrothermal alteration under relatively high-P/lowT conditions where hydrous silicates and calcium carbonate crystallized in the matrix. We believe that oxidation of the metal took place during this event along with the Fe enrichment of the surface

  20. Correlations Among Microstructure, Morphology, Chemistry, and Isotopic Systematics of Hibonite in CM Chondrites

    Science.gov (United States)

    Han, J.; Liu, M.-C..; Keller, L. P.; Davis, A. M.

    2017-01-01

    Introduction: Hibonite is a primary refractory phase occurring in many CAIs, typically with spinel and perovskite. Our microstructural studies of CAIs from carbonaceous chondrites reveal a range of stacking defect densities and correlated non-stoichiometry in hibonite. We also conducted a series of annealing experiments, demonstrating that the Mg-Al substitution stabilized the formation of defect-structured hibonite. Here, we continue a detailed TEM analysis of hibonite-bearing inclusions from CM chondrites that have been well-characterized isotopically. We examine possible correlations of microstructure, morphology, mineralogy, and chemical and isotopic systematics of CM hibonites in order to better understand the formation history of hibonite in the early solar nebula. Methods: Fifteen hibonite-bearing inclusions from the Paris CM chondrite were analyzed using a JEOL 7600F SEM and a JEOL 8530F electron microprobe. In addition to three hibonite-bearing inclusions from the Murchison CM chondrite previously reported, we selected three inclusions from Paris, Pmt1-6, 1-9, and 1-10, representing a range of 26Al/27Al ratios and minor element concentrations for a detailed TEM study. We extracted TEM sections from hibonite grains using a FEI Quanta 3D field emission gun SEM/FIB. The sections were then examined using a JEOL 2500SE field-emission scanning TEM equipped with a Thermo-Noran thin window EDX spectrometer. Results and Discussion: A total of six hibonite-bearing inclusions, including two platy hibonite crystals (PLACs) and four spinel-hibonite inclusions (SHIBs), were studied. There are notable differences in chemical and isotopic compositions between the inclusions (Table 1), indicative of their different formation environment or timing. Our TEM observations show perfectly-ordered, stoichiometric hibonite crystals without stacking defects in two PLACs, 2-7-1 and 2-8-2, and in three SHIBs, Pmt1-6, 1-9, and 1-10. In contrast, SHIB 1-9-5 hibonite grains contain a

  1. (U-Th)/He ages of phosphates from St. Séverin LL6 chondrite

    Science.gov (United States)

    Min, Kyoungwon; Reiners, Peter W.; Shuster, David L.

    2013-01-01

    We obtained single-grain (U-Th)/He ages from 14 merrillite and five chlorapatite aggregates from St. Séverin to constrain its low-T thermal history. In addition, we performed 3He/4He stepped heating diffusion experiments for merrillite and chlorapatite crystals from Guareña chondrite to better constrain He diffusion properties in chondritic phosphates in general. Among the 19 phosphate grains from St. Séverin, the five oldest merrillites and four oldest chlorapatites yielded weighted mean ages of 4412 ± 75 Ma (1σ: MSWD = 0.34) and 4152 ± 70 Ma (MSWD = 0.48), respectively. These weighted mean ages overlap with the peaks of the corresponding probability density plots, thus likely represent the most pristine (U-Th)/He ages of St. Séverin. The radiogenic 4He and proton-induced 3He diffusion experiments on Guareña chondrite resulted in two well-defined linear trends in Arrhenius plot for merrillite (radius = ˜59 μm) and chlorapatite (˜43 μm) grains. Error-weighted linear regressions of the 3He data yielded following diffusion parameters: Ea = 135.8 ± 4.8 kJ/mol, and ln(Do/a2) = 5.83 ± 0.66 ln(s-1) for merrillite; and Ea = 109.3 ± 9.7 kJ/mol, and ln(Do/a2) = 8.15 ± 1.93 ln(s-1) for chlorapatite. Assuming the analyzed fragments approximate the diffusion domain, log Do was calculated as (-1.93 ± 0.29) log(cm2/s) and (-1.19 ± 0.84) log(cm2/s) for merrillite and chlorapatite, respectively. These results indicate higher closure T for merrillite than chlorapatite. Assuming these results also apply to St. Séverin and that crystal dimensions define the limiting diffusive length-scale, the closure temperatures of merrillite and chlorapatite in St. Séverin are estimated to be 94-112 °C (for cooling rates of 0.3-2.6 °C/Ma) and 18 °C (for 0.3 °C/Ma), respectively. The new single-grain (U-Th)/He ages and 3He/4He stepped heating diffusion results, combined with previously reported Pb/Pb and 40Ar/39Ar (with updated λ-tFCs pairs) data indicate that St. S

  2. Ordinary people?

    OpenAIRE

    Lockhart, Elaine

    2007-01-01

    Petit matin ordinaire dans un casernement encore anonyme. Les hommes ont du mal à se tirer du sommeil. Ordres laconiques, gestes mécaniques qui font plus de bruit que les paroles. Lits au carré. Toilette sommaire. On est sans doute quelque part dans les Balkans. Sept soldats sont désignés pour une mission qui nécessite un trajet en bus, un armement individuel, des caisses de munitions. Les interrogations restent sans réponses. À Dzoni, jeune recrue (Relja Popovic) qui essaie de s’informer, un...

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

    Science.gov (United States)

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

    2001-01-01

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

  4. In situ oxygen isotope compositions in olivines of different types of cosmic spherules: An assessment of relationships to chondritic particles

    Digital Repository Service at National Institute of Oceanography (India)

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

    ‰, -13 to 22‰ and -11 to 6‰. Our results suggest that the oxygen isotope compositions of the scoriaceous, relict-bearing, porphyritic and barred spherules show provenance related to the carbonaceous (CM, CV, CO and CR) chondrites. The different types...

  5. Multi-scale three-dimensional characterization of iron particles in dusty olivine: Implications for paleomagnetism of chondritic meteorites

    DEFF Research Database (Denmark)

    Einsle, Joshua F.; Harrison, Richard J.; Kasama, Takeshi

    2016-01-01

    Dusty olivine (olivine containing multiple sub-micrometer inclusions of metallic iron) in chondritic meteorites is considered an ideal carrier of paleomagnetic remanence, capable of maintaining a faithful record of pre-accretionary magnetization acquired during chondrule formation. Here we show how...

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

    Science.gov (United States)

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

    2017-01-01

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

  7. The Relationship between Knowledge Management and Organizational Learning with the Effectiveness of Ordinary and Smart Secondary School Principals

    Science.gov (United States)

    Khammar, Zahra; Heidarzadegan, Alireza; Balaghat, Seyed Reza; Salehi, Hadi

    2013-01-01

    This study aimed to investigate the relationship between knowledge management and organizational learning with the effectiveness of ordinary and smart high school principals in Zahedan Pre-province. The statistical community of this research is 1350 male and female teachers teaching in ordinary and smart students of high schools in that 300 ones…

  8. Oxygen, Magnesium, and Aluminum Isotopes in the Ivuna CAI: Re-Examining High-Temperature Fractionations in CI Chondrites

    Science.gov (United States)

    Frank, D. R.; Huss, G. R.; Nagashima, K.; Zolensky, M. E.; Le, L.

    2017-01-01

    CI chondrites are thought to approximate the bulk solar system composition since they closely match the composition of the solar photosphere. Thus, chemical differences between a planetary object and the CI composition are interpreted to result from fractionations of a CI starting composition. This interpretation is often made despite the secondary mineralogy of CI chondrites, which resulted from low-T aqueous alteration on the parent asteroid(s). Prevalent alteration and the relatively large uncertainties in the photospheric abundances (approx. +/-5-10%) permit chemical fractionation of CI chondrites from the bulk solar system, if primary chondrules and/or CAIs have been altered beyond recognition. Isolated olivine and pyroxene grains that range from approx. 5 microns to several hundred microns have been reported in CI chondrites, and acid residues of Orgueil were found to contain refractory oxides with oxygen isotopic compositions matching CAIs. However, the only CAI found to be unambiguously preserved in a CI chondrite was identified in Ivuna. The Ivuna CAI's primary mineralogy, small size (approx.170 microns), and fine-grained igneous texture classify it as a compact type A. Aqueous alteration infiltrated large portions of the CAI, but other regions remain pristine. The major primary phases are melilite (Ak 14-36 ), grossmanite (up to 20.8 wt.% TiO 2 ), and spinel. Both melilite and grossmanite have igneous textures and zoning patterns. An accretionary rim consists primarily of olivine (Fa 2-17 ) and low-Ca pyroxene (Fs 2-10 ), which could be either surviving CI2 material or a third lithology.

  9. Radiative heating of carbonaceous near-Earth objects as a cause of thermal metamorphism for CK chondrites

    Science.gov (United States)

    Chaumard, Noël; Devouard, Bertrand; Delbo, Marco; Provost, Ariel; Zanda, Brigitte

    2012-07-01

    Metamorphic CK carbonaceous chondrites display matrix textures that are best explained by a transient thermal event with temperatures in the 550-950 K range and durations in the order of days to years, longer than what is commonly admitted for shock events but shorter than what is required for nuclide decay. We propose that radiative heating of small carbonaceous meteoroids with perihelia close to the Sun could account for the petrological features observed in CK chondrites. Numerical thermal modeling, using favorable known NEOs orbital parameters (perihelion distances between 0.07 and 0.15 AU) and physical properties of CV and CK chondrites (albedo in the range 0.01-0.1, 25% porosity, thermal diffusivity of 0.5-1.5 W m-1 K-1), shows that radiative heating can heat carbonaceous meteoroids in the meter size range to core temperatures up to 1050 K, consistent with the metamorphic temperatures estimated for CK chondrites. Sizes of known CV and CK chondrites indicate that all these objects were small meteoroids (radii from a few cm to 2.5 m) prior to their atmospheric entry. Simulations of dynamic orbits for NEO objects suggest that there are numerous such bodies with suitable orbits and properties, even if they are only a small percentage of all NEOs. Radiative heating would be a secondary process (superimposed on parent-body processes) affecting meteoroids formed by the disruption of an initially homogeneous CV3-type parent body. Different petrologic types can be accounted for depending on the sizes and heliocentric distances of the objects in such a swarm.

  10. The Formation and Chronology of the PAT 91501 Impact-Melt L-Chondrite with Vesicle-Metal-Sulfide Assemblages

    Science.gov (United States)

    Benedix, G. K.; Ketcham, R. A.; Wilson, L.; McCoy, T. J.; Bogard, D. D.; Garrison, D. H.; Herzog, G. F.; Xue, S.; Klein, J.; Middleton, R.

    2007-01-01

    The L chondrite Patuxent Range (PAT) 41 91501 is an 8.5-kg unshocked, homogeneous, igneous-textured impact melt that cooled slowly compared to other meteoritic impact melts in a crater floor melt sheet or sub-crater dike. We conducted mineralogical and tomographic studies of previously unstudied mm- to cm-sized metal-sulfide-vesicle assemblages and chronologic studies of the silicate host. Metal-sulfide clasts constitute about 1 vol.%, comprise zoned taenite, troilite and pentlandite, and exhibit a consistent orientation between metal and sulfide and of metal-sulfide contacts. Vesicles make up approximately 2 vol.% and exhibit a similar orientation of long axes. Ar-39-Ar-40 measurements date the time of impact at 4.461 +/- 0.008 Gyr B.P. Cosmogenic noble gases and Be-10 and Al-2l activities suggest a pre-atmospheric radius of 40-60 cm and a cosmic ray exposure age of 25-29 Myr, similar to ages of a cluster of L chondrites. PAT 91501 dates the oldest known impact on the L chondrite parent body. The dominant vesicle-forming gas was S2 (approximately 15-20 ppm), which formed in equilibrium with impact-melted sulfides. The meteorite formed in an impact melt dike beneath a crater, as did other impact melted L chondrites, such as Chico. Cooling and solidification occurred over approximately 2 hours. During this time, approximately 90% of metal and sulfide segregated from the local melt. Remaining metal and sulfide grains oriented themselves in the local gravitational field, a feature nearly unique among meteorites. Many of these metal sulfide grains adhered to vesicles to form aggregates that may have been close to neutrally buoyant. These aggregates would have been carried upward with the residual melt, inhibiting further buoyancy-driven segregation. Although similar processes operated individually in other chondritic impact melts, their interaction produced the unique assemblage observed in PAT 91501.

  11. Micro-X-ray diffraction assessment of shock stage in enstatite chondrites

    Science.gov (United States)

    Izawa, Matthew R. M.; Flemming, Roberta L.; Banerjee, Neil R.; McCausland, Philip J. A.

    2011-05-01

    A new method for assessing the shock stage of enstatite chondrites has been developed, using in situ micro-X-ray diffraction (μXRD) to measure the full width at half maximum (FWHMχ) of peak intensity distributed along the direction of the Debye rings, or chi angle (χ), corresponding to individual lattice reflections in two-dimensional XRD patterns. This μXRD technique differs from previous XRD shock characterization methods: it does not require single crystals or powders. In situ μXRD has been applied to polished thin sections and whole-rock meteorite samples. Three frequently observed orthoenstatite reflections were measured: (020), (610), and (131); these were selected as they did not overlap with diffraction lines from other phases. Enstatite chondrites are commonly fine grained, stained or darkened by weathering, shock-induced oxidation, and metal/sulfide inclusions; furthermore, most E chondrites have little olivine or plagioclase. These characteristics inhibit transmitted-light petrography, nevertheless, shock stages have been assigned MacAlpine Hills (MAC) 02837 (EL3) S3, Pecora Escarpment (PCA) 91020 (EL3) S5, MAC 02747 (EL4) S4, Thiel Mountains (TIL) 91714 (EL5) S2, Allan Hills (ALHA) 81021 (EL6) S2, Elephant Moraine (EET) 87746 (EH3) S3, Meteorite Hills (MET) 00783 (EH4) S4, EET 96135 (EH4-5) S2, Lewis Cliff (LEW) 88180 (EH5) S2, Queen Alexandra Range (QUE) 94204 (EH7) S2, LaPaz Icefield (LAP) 02225 (EH impact melt) S1; for the six with published shock stages, there is agreement with the published classification. FWHMχ plotted against petrographic shock stage demonstrates positive linear correlation. FWHMχ ranges corresponding to shock stages were assigned as follows: S1 3.5°, S6—not measured. Slabs of Abee (EH impact-melt breccia), and Northwest Africa (NWA) 2212 (EL6) were examined using μXRD alone; FWHMχ values place both in the S2 range, consistent with literature values. Micro-XRD analysis may be applicable to other shocked orthopyroxene

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

    Science.gov (United States)

    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

  13. Petrographic and C & O isotopic characteristics of the earliest stages of aqueous alteration of CM chondrites

    Science.gov (United States)

    Vacher, Lionel G.; Marrocchi, Yves; Villeneuve, Johan; Verdier-Paoletti, Maximilien J.; Gounelle, Matthieu

    2017-09-01

    CM chondrites form the largest group of hydrated meteorites and span a wide range of alteration states, with the Paris meteorite being the least altered CM described to date. Ca-Carbonates are powerful proxies for the alteration conditions of CMs because they are direct snapshots of the chemical and isotopic compositions of the parent fluids. Here, we report a petrographic and a C isotope and O isotope survey of Ca-carbonates in Paris in order to better characterize the earliest stages of aqueous alteration. Petrographic observations show that Paris contains two distinct populations of Ca-carbonates: Type 1a Ca-carbonates, which are surrounded by rims of tochilinite/cronstedtite intergrowths (TCIs), and new Type 0 Ca-carbonates, which do not exhibit the TCI rims. The TCI rims of Type 1a Ca-carbonates commonly outline euhedral crystal faces, demonstrating that these Ca-carbonates were (i) partially or totally pseudomorphosed by TCI and (ii) precipitated at the earliest stages of aqueous alteration, before Type 0 Ca-carbonates. Isotopic measurements show that Paris' Ca-carbonates have δ13C values that range from 19 to 80‰ (PDB), δ18O values that range from 29 to 41%, and δ17O values that range from 13 to 24‰ (SMOW). According to the δ13C-δ18O values of Paris' Ca-carbonates, we developed a new alteration model that involves (i) the equilibration of a primordial 17,18O-rich water (PW) with 16O-rich anhydrous silicates and (ii) varying contribution of 12C- and 13C-rich soluble organic matter (SOMs). It also suggests that many parameters control the C and O isotopic composition of Ca-carbonates, the principles being the degree of isotopic equilibration between the PW and the anhydrous silicates, the respective contribution of 12C and 13C-rich SOMs as well as the thermal evolution of CM parent bodies. Consequently, we suggest that CM Ca-carbonates could record both positive and negative δ13C-δ18O relationships, but a systematic correspondence is probably absent

  14. Estimating Shock Pressures in Chondrites From High-Pressure Minerals in Shock-induced Melt Veins

    Science.gov (United States)

    Xie, Z.; Sharp, T. G.

    2002-12-01

    High-pressure minerals are common in highly shocked (S6) L6 chondrites, occurring within or adjacent to shock-induced melt veins and melt pockets. They provide natural examples of high-pressure minerals that make up the Earth's transition zone (410 to 660 km depth) and lower mantle, as well as a record of high-pressure and temperature conditions during impact events on chondrite parent bodies. The high-pressure minerals that crystallize in melt veins and pockets can be used as an alternative means of investigating shock pressure. We used transmission electron microscopy (TEM) to characterize the shock-vein mineralogy in seven L6 chondrites ranging from shock stage S6 to S3: Tenham (S6), Umbarger (S6), Roy (S3-5), Ramsdorf (S4), Kunashak (S4), Nakhon Pathon (S4) and La Lande (S4). Tenham contains assemblages that reflect variable cooling rates during crystallization. Majorite plus magnesiow\\x81stite occur in the center of melt veins, whereas ringwoodite, akimotoite and round amorphous grains (probably vitrified MgSiO3-pervoskite) occur along melt-vein edges. In addition, a symplectitic intergrowth of majorite and an amorphous phase has been observed, which probably represents clinopyroxene that has disassociated into majorite plus CaSiO3-pervoskite. High pressure minerals in the Umbarger melt veins include: ringwoodite, akimotoite ((Mg,Fe)SiO3-ilmenite), augite, and hollandite-structured plagioclase. In addition, Fe2SiO4-spinel (new mineral) and stishovite occur in SiO2-FeO rich melt. High-pressure minerals in the Roy melt veins include ringwoodite and majorite. Melt veins in Ramsdorf, Kunashak, Nakhon Pathon and La lande contain fine-grained olivines and pyroxenes that are defect free and interpreted as having crystallized from the melt. Crystallization pressures can be inferred from the mineral assemblages in the melt veins and available phase equilibrium data. Melt veins in Tenham crystallized at pressure of approximately 25 GPa; Umbarger at pressure between 18

  15. Shock effects in “EH6” enstatite chondrites and implications for collisional heating of the EH and EL parent asteroids

    Science.gov (United States)

    Rubin, Alan E.; Wasson, John T.

    2011-07-01

    Of the six chondrites that were listed as EH6 or EH6-an during the course of this study, we confirm the EH classification of Y-8404, Y-980211 and Y-980223 and the EH-an classification of Y-793225; two chondrites (A-882039 and Y-980524) are reclassified as EL (the former contains ferroan alabandite and both contain kamacite with ˜1 wt% Si). All of the meteorites contain euhedral enstatite grains surrounded by metal ± sulfide (although this texture is rare in Y-793225), consistent with enstatite crystallizing from a mixed melt. All contain enstatite with chondrites average 0.25 wt% Mn in troilite. (Literature data show that typical EH3-EH5 chondrites contain enstatite with 0.13-0.20 wt% MnO and troilite with 0.05-0.11 wt% Mn.) The three EH chondrites contain keilite [(Fe >0.5,Mg chondrites. We suggest that all six meteorites have experienced impact melting; Mn was preferentially partitioned into sulfide during subsequent crystallization. The silica-rich samples may have become enriched in the aftermath of the impact by a redox reaction involving FeO and reduced Si. A-882039, Y-8404, Y-980211, Y-980223 and Y-980524 were incompletely melted; they contain rare relict chondrules and are classified as impact-melt breccias; Y-793225 is a chondrule-free impact-melt rock. If these EH and EH-an chondrites (which were previously listed as petrologic type 6) have, in fact, been impact melted, it seems plausible that collisional heating is generally responsible for EH-chondrite metamorphism. This is consistent with literature data showing that a large fraction (⩾0.7) of those chondrites classified EH5-7 and a significant fraction (⩾0.3) of those chondrites classified EH4 and EH4/5 possess textural and mineralogical properties suggestive of impact melting. In addition, ˜60% of classified EL6-7 chondrites (now including A-882039 and Y-980524) appear to have formed by impact melting. It thus seems likely that collisional heating is mainly responsible for EL- and EH-chondrite

  16. Low Dimensional Vessiot-Guldberg-Lie Algebras of Second-Order Ordinary Differential Equations

    Directory of Open Access Journals (Sweden)

    Rutwig Campoamor-Stursberg

    2016-03-01

    Full Text Available A direct approach to non-linear second-order ordinary differential equations admitting a superposition principle is developed by means of Vessiot-Guldberg-Lie algebras of a dimension not exceeding three. This procedure allows us to describe generic types of second-order ordinary differential equations subjected to some constraints and admitting a given Lie algebra as Vessiot-Guldberg-Lie algebra. In particular, well-known types, such as the Milne-Pinney or Kummer-Schwarz equations, are recovered as special cases of this classification. The analogous problem for systems of second-order differential equations in the real plane is considered for a special case that enlarges the generalized Ermakov systems.

  17. Resetting of circadian melatonin and cortisol rhythms in humans by ordinary room light

    Science.gov (United States)

    Boivin, D. B.; Czeisler, C. A.

    1998-01-01

    The present study was designed to investigate whether a weak photic stimulus can reset the endogenous circadian rhythms of plasma melatonin and plasma cortisol in human subjects. A stimulus consisting of three cycles of 5 h exposures to ordinary room light (approximately 180 lux), centered 1.5 h after the endogenous temperature nadir, significantly phase-advanced the plasma melatonin rhythm in eight healthy young men compared with the phase delays observed in eight control subjects who underwent the same protocol but were exposed to darkness (p melatonin and plasma cortisol maintained stable temporal relationships with the endogenous core body temperature cycle, consistent with the conclusion that exposure to ordinary indoor room light had shifted a master circadian pacemaker.

  18. Resetting of circadian melatonin and cortisol rhythms in humans by ordinary room light

    Science.gov (United States)

    Boivin, D. B.; Czeisler, C. A.

    1998-01-01

    The present study was designed to investigate whether a weak photic stimulus can reset the endogenous circadian rhythms of plasma melatonin and plasma cortisol in human subjects. A stimulus consisting of three cycles of 5 h exposures to ordinary room light (approximately 180 lux), centered 1.5 h after the endogenous temperature nadir, significantly phase-advanced the plasma melatonin rhythm in eight healthy young men compared with the phase delays observed in eight control subjects who underwent the same protocol but were exposed to darkness (p rhythms of plasma melatonin and plasma cortisol maintained stable temporal relationships with the endogenous core body temperature cycle, consistent with the conclusion that exposure to ordinary indoor room light had shifted a master circadian pacemaker.

  19. An introduction to linear ordinary differential equations using the impulsive response method and factorization

    CERN Document Server

    Camporesi, Roberto

    2016-01-01

    This book presents a method for solving linear ordinary differential equations based on the factorization of the differential operator. The approach for the case of constant coefficients is elementary, and only requires a basic knowledge of calculus and linear algebra. In particular, the book avoids the use of distribution theory, as well as the other more advanced approaches: Laplace transform, linear systems, the general theory of linear equations with variable coefficients and variation of parameters. The case of variable coefficients is addressed using Mammana’s result for the factorization of a real linear ordinary differential operator into a product of first-order (complex) factors, as well as a recent generalization of this result to the case of complex-valued coefficients.

  20. Prediction of the Spatial Distribution of Bovine Endemic Fluorosis Using Ordinary Kriging

    Directory of Open Access Journals (Sweden)

    Li Lin

    2015-04-01

    Full Text Available The aim of the studies was to develop an alternative method which could overcome the lack of sampling to improve the efficiency of control efforts for bovine endemic fluorosis. The spatial distribution characteristics of the disease were analysed and a prediction model for the estimation of fluorosis distribution in some districts in northwest Liaoning province in China was established. The model used ordinary kriging, and was evaluated using cross-validation. Analysis showed that the distribution of the disease was spatial autocorrelation. The prediction error of the cross-validation (ME = -0.0092, PMSE = 0.627, AKSE = 0.597, and RMSP = 1.007 and comparison with the actual disease distribution indicated that the prediction map accurately distributed bovine endemic fluorosis. It is feasible to predict bovine endemic fluorosis in the area by using ordinary kriging and limited data.

  1. Diffusion of Siderophile Elements in Fe Metal: Application to Zoned Metal Grains in Chondrites

    Science.gov (United States)

    Righter, K.; Campbell, A. J.; Humajun, M.

    2003-01-01

    The distribution of highly siderophile elements (HSE) in planetary materials is controlled mainly by metal. Diffusion processes can control the distribution or re-distribution of these elements within metals, yet there is little systematic or appropriate diffusion data that can be used to interpret HSE concentrations in such metals. Because our understanding of isotope chronometry, redox processes, kamacite/taenite-based cooling rates, and metal grain zoning would be enhanced with diffusion data, we have measured diffusion coefficients for Ni, Co, Ga, Ge, Ru, Pd, Ir and Au in Fe metal from 1200 to 1400 C and 1 bar and 10 kbar. These new data on refractory and volatile siderophile elements are used to evaluate the role of diffusional processes in controlling zoning patterns in metal-rich chondrites.

  2. The identification of group II inclusions in carbonaceous chondrites by electron probe microanalysis of perovskite

    Science.gov (United States)

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

    1985-01-01

    The technique developed by Kornacki (1984) for identifying group II Ca/Al-rich inclusions in carbonaceous chondrites by electron-microprobe analysis of the ZrO2 or Y2O3 content of their perovskite component is demonstrated using material from 20 Allende inclusions. The results are presented in tables and graphs and compared with findings obtained by other procedures. Group II inclusions are found to have perovskites generally containing less than 0.10 wt pct ZrO2 and/or Y2O3 (average of several grains), while those of groups I, III, V, and VI have more than 0.25 wt pct ZrO2. Analysis of data on eight Allende Ca/Al-rich inclusions shows that 75 percent of the fine-grained inclusions belong to group II. The implications of these findings for fractionation processes in the primitive solar nebula are indicated.

  3. The Majorite-Pyrope + Magnesiowustite Assemblage: Constraints on the History of Shock Veins in Chondrites

    Science.gov (United States)

    Chen, Ming; Sharp, Thomas G.; El Goresy, Ahmed; Wopenka, Brigitte; Xie, Xiande

    1996-03-01

    Shock veins in the Sixiangkou (L6) chondrite contain two high-pressure assemblages: (i) majorite-pyrope solid solution plus magnesiowustite that crystallized at high pressures and temperatures from a shock-induced silicate melt of bulk Sixiangkou composition and (ii) ringwoodite plus low-calcium majorite that were produced by solid-state transformation of olivine and low-calcium pyroxene. The morphology and chemistry of the majorite-pyrope garnet and the size of the magnesiowustite crystals indicate a longer duration at high pressure and temperature than predicted by impact scenarios. This pressure-temperature regime is constrained by the olivine-ringwoodite and orthopyroxene-majorite phase transformations, fusion of the meteorite constituents, and crystallization of majorite-pyrope solid solution plus magnesiowustite from that melt under high pressure.

  4. Polycrystalline and Intracrystalline Growth of Akimotoite in Clinoenstatite of the L-6 Tenham Chondrite

    Science.gov (United States)

    Ferroir, T.; Beck, P.; Gillet, P.; Simionovici, A.; Bohn, M.; Dubrovinsky, L.; El Goresy, A.

    2006-12-01

    Akimotoite was first reported by [1] in the Tenham chondrite as aggregates adjacent to clinoenstatite entrained in shock melt vein. We report the presence in the same chondrite of a large clinoenstatite grain partially transformed into akimotoite due to shock by two different mechanisms : (1) phase transition commencing at grain boundaries leading to polycrystalline akimotoite and (2) intracrystalline phase transition commencing from the polycrystalline akimotoite as thin lamellae extending to the grain interior. We conducted a detailed survey of these transformations by reflected light microscopy, Raman analysis and mapping, SEM, X-ray diffraction and electron microprobe analysis and mapping to better constrain phase transformation and element partitioning between the two phases. Polycrystalline aggregate consist mainly of akimotoite from which thin lamellae of akimotoite emerge. Reflected light analysis and Raman mapping allowed to unambiguously identify the two phases. Synchrotron XRD analysis allowed to refine the structure to the R-3 space group with cell parameters of a=4.71(2)Å and c=13.25(3) Å for a volume of V=254(4)Å3 thus suggesting a high residual stress of a few GPa according to initial volume and bulk moduli [2]. Microprobe analysis shows a difference in composition between polycrystalline akimotoite (Fe0.35Mg0.6Ca0.05)SiO3 and clinoenstatite but no differences between akimotoite lamellae and clinoenstatite. In contrast to [1], Ca is higher in akimotoite (CaO = 1.74 %wt) than in clinoenstatite (CaO=0.71%wt). The results support the shock origin and suggest calcium diffusion to akimotoite from the adjacent chondritic melt. Intracrystalline transformation commences from the polycrystalline akimotoite producing parallel lamellae with the same chemical composition as the host clinoenstatite. Thus, the growth of akimotoite would first involve isochemical solid state transformation followed by chemical redistribution of Ca with the melt

  5. The Analytical Solution of Some Fractional Ordinary Differential Equations by the Sumudu Transform Method

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    Hasan Bulut

    2013-01-01

    Full Text Available We introduce the rudiments of fractional calculus and the consequent applications of the Sumudu transform on fractional derivatives. Once this connection is firmly established in the general setting, we turn to the application of the Sumudu transform method (STM to some interesting nonhomogeneous fractional ordinary differential equations (FODEs. Finally, we use the solutions to form two-dimensional (2D graphs, by using the symbolic algebra package Mathematica Program 7.

  6. A nonlinear ordinary differential equation associated with the quantum sojourn time

    Energy Technology Data Exchange (ETDEWEB)

    Benguria, Rafael D [Facultad de Fisica, Pontificia Universidad Catolica de Chile, Santiago (Chile); Duclos, Pierre [Universite de Toulon, CPT-CNRS (France); Fernandez, Claudio [Anestoc-Facultad de Matematicas, Pontificia Universidad Catolica de Chile, Santiago (Chile); Sing-Long, Carlos, E-mail: rbenguri@fis.puc.c, E-mail: cfernand@mat.puc.c, E-mail: casinglo@gmail.co [Centro de Imagenes Biomedicas, Pontificia Universidad Catolica de Chile, Santiago (Chile)

    2010-11-26

    We study a nonlinear ordinary differential equation on the half-line, with the Dirichlet boundary condition at the origin. This equation arises when studying the local maxima of the sojourn time for a free quantum particle whose states belong to an adequate subspace of the unit sphere of the corresponding Hilbert space. We establish several results concerning the existence and asymptotic behavior of the solutions.

  7. On global asymptotic stability of solutions of a system of ordinary differential equations

    Science.gov (United States)

    Filimonov, M. Yu.

    2017-12-01

    To investigate global asymptotic stability in general of an equilibrium position of an autonomous system of ordinary differential equations, considered by V.A. Pliss, a function different from the Lyapunov functions is applied. V.A. Pliss proved that for this system it is impossible to construct the Lyapunov function as a sum of a quadratic form and an integral of some nonlinear function defined by the right-hand side of the system.

  8. p-adic string theories provide lattice Discretization to the ordinary string worldsheet.

    Science.gov (United States)

    Ghoshal, Debashis

    2006-10-13

    A class of models called p-adic strings is useful in understanding the tachyonic instability of string theory. These are found to be empirically related to the ordinary strings in the p-->1 limit. We propose that these models provide discretization for the string worldsheet and argue that the limit is naturally thought of as a continuum limit in the sense of the renormalization group.

  9. Ordinary kriging approach to predicting long-term particulate matter concentrations in seven major Korean cities

    Directory of Open Access Journals (Sweden)

    Sun-Young Kim

    2014-09-01

    Full Text Available Objectives Cohort studies of associations between air pollution and health have used exposure prediction approaches to estimate individual-level concentrations. A common prediction method used in Korean cohort studies is ordinary kriging. In this study, performance of ordinary kriging models for long-term particulate matter less than or equal to 10 μm in diameter (PM10 concentrations in seven major Korean cities was investigated with a focus on spatial prediction ability. Methods We obtained hourly PM10 data for 2010 at 226 urban-ambient monitoring sites in South Korea and computed annual average PM10 concentrations at each site. Given the annual averages, we developed ordinary kriging prediction models for each of the seven major cities and for the entire country by using an exponential covariance reference model and a maximum likelihood estimation method. For model evaluation, cross-validation was performed and mean square error and R-squared (R2 statistics were computed. Results Mean annual average PM10 concentrations in the seven major cities ranged between 45.5 and 66.0 μg/m3 (standard deviation=2.40 and 9.51 μg/m3, respectively. Cross-validated R2 values in Seoul and Busan were 0.31 and 0.23, respectively, whereas the other five cities had R2 values of zero. The national model produced a higher crossvalidated R2 (0.36 than those for the city-specific models. Conclusions In general, the ordinary kriging models performed poorly for the seven major cities and the entire country of South Korea, but the model performance was better in the national model. To improve model performance, future studies should examine different prediction approaches that incorporate PM10 source characteristics.

  10. Bayesian inference for infectious disease transmission models based on ordinary differential equations

    OpenAIRE

    Weidemann, Felix

    2015-01-01

    Predicting the epidemiological effects of new vaccination programmes through mathematical-statistical transmission modelling is of increasing importance for the German Standing Committee on Vaccination. Such models commonly capture large populations utilizing a compartmental structure with its dynamics being governed by a system of ordinary differential equations (ODEs). Unfortunately, these ODE-based models are generally computationally expensive to solve, which poses a challenge for any sta...

  11. Ordinary kriging approach to predicting long-term particulate matter concentrations in seven major Korean cities.

    Science.gov (United States)

    Kim, Sun-Young; Yi, Seon-Ju; Eum, Young Seob; Choi, Hae-Jin; Shin, Hyesop; Ryou, Hyoung Gon; Kim, Ho

    2014-01-01

    Cohort studies of associations between air pollution and health have used exposure prediction approaches to estimate individual-level concentrations. A common prediction method used in Korean cohort studies is ordinary kriging. In this study, performance of ordinary kriging models for long-term particulate matter less than or equal to 10 μm in diameter (PM10) concentrations in seven major Korean cities was investigated with a focus on spatial prediction ability. We obtained hourly PM10 data for 2010 at 226 urban-ambient monitoring sites in South Korea and computed annual average PM10 concentrations at each site. Given the annual averages, we developed ordinary kriging prediction models for each of the seven major cities and for the entire country by using an exponential covariance reference model and a maximum likelihood estimation method. For model evaluation, cross-validation was performed and mean square error and R-squared (R(2)) statistics were computed. Mean annual average PM10 concentrations in the seven major cities ranged between 45.5 and 66.0 μg/m(3) (standard deviation=2.40 and 9.51 μg/m(3), respectively). Cross-validated R(2) values in Seoul and Busan were 0.31 and 0.23, respectively, whereas the other five cities had R(2) values of zero. The national model produced a higher crossvalidated R(2) (0.36) than those for the city-specific models. In general, the ordinary kriging models performed poorly for the seven major cities and the entire country of South Korea, but the model performance was better in the national model. To improve model performance, future studies should examine different prediction approaches that incorporate PM10 source characteristics.

  12. On one two-point BVP for the fourth order linear ordinary differential equation

    Czech Academy of Sciences Publication Activity Database

    Mukhigulashvili, Sulkhan; Manjikashvili, M.

    2017-01-01

    Roč. 24, č. 2 (2017), s. 265-275 ISSN 1072-947X Institutional support: RVO:67985840 Keywords : fourth order linear ordinary differential equations * two-point boundary value problems Subject RIV: BA - General Mathematics Impact factor: 0.290, year: 2016 https://www.degruyter.com/view/j/gmj.2017.24.issue-2/gmj-2016-0077/gmj-2016-0077. xml

  13. Physiological effects of acute and ordinary bed rest conditions on endurance trained volunteers.

    Science.gov (United States)

    Zorbas, Y. G.; Ivanov, A. A.; Madvedev, S. N.; Kakurin, A. G.

    1999-12-01

    The aim of this study was to carry out a comparative study of water balance and water protein composition of the blood during exposure to acute (abrupt restriction of motor activity) and ordinary rigorous bed rest of 7 days. The studies were performed on 30 long distance runners aged 22-25 years old who had a VO 2 max of 66 ml kg -1·min -1 on the average. The volunteers were divided into three equal groups: the volunteers in the 1st group were under a normal ambulatory life conditions (control subjects), the volunteers of the 2nd group subjected to an acute bed rest (abrupt restriction of motor activity) regime (acute bed rested subjects) and the volunteers of the 3rd group were submitted to ordinary and rigorous bed rest (rigorous bed rested subjects). All volunteers were on an average of 13.8 km/day before taking part in this investigation. The 2nd and 3rd groups of volunteers were kept under a rigorous bed rest regime for 7 days. During the prebed rest period and actual bed rest period plasma volume (PV), total protein and protein fractions (albumins and globulins) and hematocrit were measured. Exposure to acute bed rest conditions induced a significant increase in hematocrit, hemoglobin concentration, protein fractions and marked decrease in (PV) and water balance which were significantly more pronounced than during exposure to ordinary rigorous bed rest. It was concluded that exposure to acute bed rest conditions induces significantly greater changes in water balance and water-protein concentration of the blood of endurance trained volunteers than exposure to ordinary rigorous bed rest conditions.

  14. Insight into the dynamics of low temperature dielectric relaxation of ordinary perovskite ferroelectrics

    OpenAIRE

    Levit Valenzuela, Rafael; Ochoa Guerrero, Diego A.; Martínez García, Julio Cesar; García García, José Eduardo

    2017-01-01

    The temperature dependence of the dielectric response of ordinary ferroelectric materials exhibits a frequency-independent anomalous peak as a manifestation of the ferroelectric to paraelectric phase transition. A second anomaly in the permittivity has been reported in different ferroelectric perovskite-type systems at low temperatures, often at cryogenic temperatures. This anomaly manifests as a frequency-dependent local maximum, which exhibits similar characteristics to that observed in rel...

  15. Hydrologic Modeling and Flood Frequency Analysis for Ordinary High Water Mark Delineation

    Science.gov (United States)

    2016-02-01

    climate change may cause systematic changes in the frequency of flood events; climatic trends are notoriously difficult to see in hydrologic...precipitation. Snowmelt or rain-on-snow events can cause larger floods than a simple rain event. Also, dam retention, diversions, and other flow...ER D C/ CR RE L TR -1 6- 2 Wetland Regulatory Assistance Program (WRAP) Hydrologic Modeling and Flood Frequency Analysis for Ordinary

  16. Dietary and oral hygiene habits of active athletes and adolescents attending ordinary junior high schools.

    Science.gov (United States)

    Anttonen, Vuokko; Kemppainen, Anna; Niinimaa, Ahti; Pesonen, Paula; Tjäderhane, Leo; Jaana, Laitinen

    2014-09-01

    Active sports require sufficient energy intake. How do young athletes meet this need? The aim of this study was to investigate self-reported health and oral behaviors of young athletes and to compare them with a population-based sample of ordinary adolescents. A computer-based questionnaire on oral hygiene habits and dietary habits was conducted in two junior high schools with special classes for athletes in 2011. Adolescents of similar age (n=1230) attending ordinary classes had responded the same questionnaire earlier in the city of Oulu (in 2004) and in Kajaani, Finland (in 2006-2007). Answers to individual questions as well as sum scores of the answers were analyzed. The answers of the athletes and ordinary adolescents were analyzed by gender using cross-tabulation and chi-square testing. The mean sum score of the athletes indicated their more favorable health behavior compared with the other adolescents. They also ate more frequently the four daily than the others; in addition, they ate the school lunch as an entity which it was intended. However, the athlete boys consumed more fizzy/soft drinks and ate chocolate more often than the rest. The athletes also brushed their teeth more frequently than ordinary adolescents. Oral health behavior of the girls was better than that of the boys. Health behavior of the young athletes is better than that of other adolescents. Continuous oral health education should be targeted to all adolescents; growing boys should be target group of information on healthy sources of energy. © 2013 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. Probabilistic assessment of steel moment frames incremental collapse (ordinary, intermediate and special under earthquake

    Directory of Open Access Journals (Sweden)

    Kourosh Mehdizadeh

    2017-11-01

    Full Text Available Building collapse is a level of the structure performance in which the amount of financial and life loss is maximized, so this event could be the worst incident in the construction. Regarding to the possibility of destructive earthquakes in different parts of the world, detailed assessment of the structure's collapse has been one of the major challenges of the structural engineering. In this regard, offering models based on laboratory studies, considering the effective parameters and appropriate earthquakes could be a step towards achieving this goal. In this research, a five-story steel structure with a system of ordinary, intermediate and special moment frame (low, intermediate and high ductility has been designed based on the local regulations. In this study, the effect of resistance and stiffness deterioration of the structural elements based on the results of the laboratory models have been considered and the ductility role in the collapse capacity of steel moment frames has been investigated as probabilistic matter. For this purpose, incremental dynamic analysis has been done under 50 pairs of earthquake records proposing FEMA P695 instruction and fragility curves of various performance levels are developed. Results showed higher collapse capacity of special moment steel frame than the intermediate and ordinary moment frames. In the 50 percent probability level, the collapse capacity of special moment frame increased 34 % compared to the intermediate moment frame and 66 % to the ordinary moment frame. Also, the results showed that for different collapse spectral accelerations, the use of special moment frame instead of intermediate and ordinary moment frames reduces the collapse probability to 30 and 50 % respectively.

  18. Influence of Temperature on Workability and Compressive Strength of Ordinary Concrete with High Calcium Fly Ash

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    Gołaszewski Jacek

    2017-06-01

    Full Text Available The rheological properties of fresh ordinary concrete are closely affected by temperature and time. The paper presents the study of consistency of fresh concrete mixtures made with Portland cement and cement with calcareous fly ash. Two types of admixtures were used. It was proven that the temperature has a clear effect on workability and compressive strength concrete. Influence on workability can be reduced by selecting the appropriate superplasticizer and cement.

  19. On nonlocal problems for ordinary differential equations and on a nonlocal parabolic transmission problem

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    M. Denche

    1999-01-01

    Full Text Available In the present paper we study nonlocal problems for ordinary differential equations with a discontinuous coefficient for the high order derivative. We establish sufficient conditions, known as regularity conditions, which guarantee the coerciveness for both the space variable and the spectral parameter, as well as guarantee the completeness of the system of root functions. The results obtained are then applied to the study of a nonlocal parabolic transmission problem.

  20. Park Forest (L5) and the asteroidal source of shocked L chondrites

    Science.gov (United States)

    Meier, Matthias M. M.; Welten, Kees C.; Riebe, My E. I.; Caffee, Marc W.; Gritsevich, Maria; Maden, Colin; Busemann, Henner

    2017-08-01

    The Park Forest (L5) meteorite fell in a suburb of Chicago, Illinois (USA) on March 26, 2003. It is one of the currently 25 meteorites for which photographic documentation of the fireball enabled the reconstruction of the meteoroid orbit. The combination of orbits with pre-atmospheric sizes, cosmic-ray exposure (CRE), and radiogenic gas retention ages ("cosmic histories") is significant because they can be used to constrain the meteoroid's "birth region," and test models of meteoroid delivery. Using He, Ne, Ar, 10Be, and 26Al, as well as a dynamical model, we show that the Park Forest meteoroid had a pre-atmospheric size close to 180 g cm-2, 0-40% porosity, and a pre-atmospheric mass range of 2-6 tons. It has a CRE age of 14 ± 2 Ma, and (U, Th)-He and K-Ar ages of 430 ± 90 and 490 ± 70 Ma, respectively. Of the meteorites with photographic orbits, Park Forest is the second (after Novato) that was shocked during the L chondrite parent body (LCPB) break-up event approximately 470 Ma ago. The suggested association of this event with the formation of the Gefion family of asteroids has recently been challenged and we suggest the Ino family as a potential alternative source for the shocked L chondrites. The location of the LCPB break-up event close to the 5:2 resonance also allows us to put some constraints on the possible orbital migration paths of the Park Forest meteoroid.