ABOUT THIS COLLECTION

Meteoritics & Planetary Science is an international monthly journal of the Meteoritical Society—a scholarly organization promoting research and education in planetary science. Topics include the origin and history of the solar system, planets and natural satellites, interplanetary dust and interstellar medium, lunar samples, meteors and meteorites, asteroids, comets, craters, and tektites.

Meteoritics & Planetary Science was first published in 1935 under the title Contributions of the Society for Research on Meteorites. In 1947, the publication became known as Contributions of the Meteoritical Society and continued through 1951. From 1953 to 1995, the publication was known as Meteoritics, and in 1996, the journal's name was changed to Meteoritics & Planetary Science or MAPS. The journal was not published in 1952 and from 1957 to 1964.

This archive provides access to Meteoritics & Planetary Science Volumes 37-44 (2002-2009).

Visit Wiley Online Library for new and retrospective Meteoritics & Planetary Science content (1935-present).

ISSN: 1086-9379

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Recent Submissions

  • Predictions for the LCROSS mission

    Korycansky, D. G.; Plesko, C. S.; Jutzi, M.; Asphaug, E.; Colaprete, A. (The Meteoritical Society, 2009-01-01)
    We describe the results of a variety of model calculations for predictions of observable results of the LCROSS mission to be launched in 2009. Several models covering different aspects of the event are described along with their results. Our aim is to bracket the range of expected results and produce a useful guide for mission planning. In this paper, we focus on several different questions, which are modeled by different methods. The questions include the size of impact crater, the mass, velocity, and visibility of impact ejecta, and the mass and temperature of the initial vapor plume. The mass and velocity profiles of the ejecta are of primary interest, as the ejecta will be the main target of the S-S/C observations. In particular, we focus on such quantities as the amount of mass that reaches various heights. A height of 2 km above the target is of special interest, as we expect that the EDUS impact will take place on the floor of a moderate-sized crater ~30 km in diameter, with a rim height of 12 km. The impact ejecta must rise above the crater rim at the target site in order to scatter sunlight and become visible to the detectors aboard the S-S/C. We start with a brief discussion of crater scaling relationships as applied to the impact of the EDUS second stage and resulting estimated crater diameter and ejecta mass. Next we describe results from the RAGE hydrocode as applied to modeling the short time scale (t 0.1 s) thermal plume that is expected to occur immediately after the impact. We present results from several large-scale smooth-particle hydrodynamics (SPH) calculations, along with results from a ZEUS-MP hydrocode model of the crater formation and ejecta mass-velocity distribution. We finish with two semi-analytic models, the first being a Monte Carlo model of the distribution of expected ejecta, based on scaling models using a plausible range of crater and ejecta parameters, and the second being a simple model of observational predictions for the shepherding spacecraft (S-S/C) that will follow the impact for several minutes until its own impact into the lunar surface. For the initial thermal plume, we predict an initial expansion velocity of ~7 km s^(-1), and a maximum temperature of ~1200 K. Scaling relations for crater formation and the SPH calculation predict a crater with a diameter of ~15 m, a total ejecta mass of ~106 kg, with ~10^4 kg reaching an altitude of 2 km above the target. Both the SPH and ZEUS-MP calculations predict a maximum ejecta velocity of ~1 km s^(-1). The semi-analytic Monte Carlo calculations produce more conservative estimates (by a factor of ~5) for ejecta at 2 km, but with a large dispersion in possible results.
  • Nebular history of amoeboid olivine aggregates

    Sugiura, N.; Petaev, M. I.; Kimura, M.; Miyazaki, A.; Hiyagon, H. (The Meteoritical Society, 2009-01-01)
    Minor element (Ca, Cr, and Mn) concentrations in amoeboid olivine aggregates (AOAs) from primitive chondrites were measured and compared with those predicted by equilibrium condensation in the solar nebula. CaO concentrations in forsterite are low, particularly in porous aggregates. A plausible explanation appears that an equilibrium Ca activity was not maintained during the olivine condensation. CaO and MnO in forsterite are negatively correlated, with CaO being higher in compact aggregates. This suggests that the compact aggregates formed either by a prolonged reheating of the porous aggregates or by condensation and aggregation of forsterite during a very slow cooling in the nebula.
  • Clastic matrix in EH3 chondrites

    Rubin, A. E.; Griset, C. D.; Choi, B.-G.; Wasson, J. T. (The Meteoritical Society, 2009-01-01)
    Patches of clastic matrix (15 to 730 m in size) constitute 4.9 vol% of EH3 Yamato (Y-) 691 and 11.7 vol% of EH3 Allan Hills (ALH) 81189. Individual patches in Y-691 consist of 1) ~25 vol% relatively coarse opaque grain fragments and polycrystalline assemblages of kamacite, schreibersite, perryite, troilite (some grains with daubrelite exsolution lamellae), niningerite, oldhamite, and caswellsilverite; 2) ~30 vol% relatively coarse silicate grains including enstatite, albitic plagioclase, silica and diopside; and 3) an inferred fine nebular component (~45 vol%) comprised of submicrometer-size grains. Clastic matrix patches in ALH 81189 contain relatively coarse grains of opaques (~20 vol%; kamacite, schreibersite, perryite and troilite) and silicates (~30 vol%; enstatite, silica and forsterite) as well as an inferred fine nebular component (~50 vol%). The O-isotopic composition of clastic matrix in Y-691 is indistinguishable from that of olivine and pyroxene grains in adjacent chondrules; both sets of objects lie on the terrestrial mass-fractionation line on the standard three-isotope graph. Some patches of fine-grained matrix in Y-691 have distinguishable bulk concentrations of Na and K, inferred to be inherited from the solar nebula. Some patches in ALH 81189 differ in their bulk concentrations of Ca, Cr, Mn, and Ni. The average compositions of matrix material in Y-691 and ALH 81189 are similar but not identical—matrix in ALH 81189 is much richer in Mn (0.23 +/- 0.05 versus 0.07 +/- 0.02 wt%) and appreciably richer in Ni (0.36 +/- 0.10 versus 0.18 +/- 0.05 wt%) than matrix in Y-691. Each of the two whole-rocks exhibits a petrofabric, probably produced by shock processes on their parent asteroid.
  • An early I-Xe age for CB chondrite chondrule formation, and a re-evaluation of the closure age of Shallowater enstatite

    Gilmour, J. D.; Crowther, S. A.; Busfield, A.; Holland, G.; Whitby, J. A. (The Meteoritical Society, 2009-01-01)
    The iodine-xenon system has been analyzed in samples of 7 chondrules from the CB chondrites Gujba and Hammadah al Hamra (HaH) 237. One sample from Gujba defined a high temperature iodine-xenon isochron corresponding to closure 1.87 +/- 0.4 Ma before closure of Shallowater enstatite. Motivated by this result, we employ outlier rejection to re-evaluate the Shallowater age, leading to a modified value of 4562.3 +/- 0.4 Ma (1). In this process, the datum obtained by combining our I-Xe age for Gujba with the literature Pb-Pb age is rejected as an outlier, indicating that in this sample the I-Xe system closed earlier than the accepted Pb-Pb age of chondrules from CB chondrites. The need for a formation environment distinct from that of chondrules from other meteorites is thus reduced.
  • Druse clinopyroxene in D'Orbigny angritic meteorite studied by single-crystal X-ray diffraction, electron microprobe analysis, and Mössbauer spectroscopy

    Abdu, Y. A.; Scorzelli, R. B.; Varela, M. E.; Kurat, G.; Azevedo, I. de Souza; Stewart, S. J.; Hawthorne, F. C. (The Meteoritical Society, 2009-01-01)
    The crystal structure of druse clinopyroxene from the D'Orbigny angrite, (Ca0.944 Fe2+ 0.042 Mg0.010Mn0.004) (Mg0.469Fe2+ 0.317Fe3+ 0.035Al0.125Cr0.010Ti0.044) (Si1.742Al0.258) O6, a = 9.7684(2), b = 8.9124(2), c = 5.2859(1) Å, β = 105.903(1) degrees, V = 442.58 ^3, space group C2/c, Z = 2, has been refined to an R1 index of 1.92% using single-crystal X-ray diffraction data. The unit formula, calculated from electron microprobe analysis, and the refined site scattering values were used to assign site populations. The distribution of Fe2+ and Mg over the M1 and M2 sites suggests a closure temperature of 1000 degrees C. Mössbauer spectroscopy measurements were done at room temperature on a single crystal and a powdered sample. The spectra are adequately fit by a Voigt-based quadrupole-splitting distribution model having two generalized sites, one for Fe2+ with two Gaussian components and one for Fe3+ with one Gaussian component. The two ferrous components are assigned to Fe2+ at the M1 site, and arise from two different next-nearest-neighbor configurations of Ca and Fe cations at the M2 site: (3Ca,0Fe) and (2Ca,1Fe). The Fe3+/Fetot ratio determined by Mössbauer spectroscopy is in agreement with that calculated from the electron microprobe analysis. The results are discussed in connection with the redox and thermal history of D'Orbigny.
  • Rapid contamination during storage of carbonaceous chondrites prepared for micro FTIR measurements

    Kebukawa, Y.; Nakashima, S.; Otsuka, T.; Nakamura-Messenger, K.; Zolensky, M. E. (The Meteoritical Society, 2009-01-01)
    Organic contamination (~2965 and ~1260 cm^(-1) peaks) was found on Tagish Lake (C2) and Murchison (CM2) carbonaceous chondrites containing abundant hydrous minerals by Fourier transform infrared (FTIR) microspectroscopy on the samples pressed on Al plates. On the other hand, anhydrous chondrite (Moss, CO3) was not contaminated. This contamination occurred within one day of storage, when the samples pressed on Al were stored within containers including silicone rubber mats. Volatile molecules having similar peaks to the contaminants were detected by long-path gas cell FTIR measurements for the silicone rubber mat. Rapid adsorption of the volatile contaminants also occurred when silica gel and hydrous minerals such as serpentine were stored in containers including silicone rubber, silicone grease, or adhesive tape. However, they did not show any contamination when stored in glass and polystyrene containers without these compounds. Therefore, precious astronomical samples such as meteorites, interplanetary dust particles (IDPs), and mission-returned samples from comets, asteroids, and Mars, should be measured by micro FTIR within one day of storage in glass containers without silicone rubber, silicone grease, or adhesive tape.
  • A condensation model for the formation of chondrules in enstatite chondrites

    Blander, M.; Pelton, A. D.; Jung, I.-H. (The Meteoritical Society, 2009-01-01)
    It is proposed that the chondrules in enstatite chondrites formed near the Sun from rain-like supercooled liquid silicate droplets and condensed Fe-Ni alloys in thermodynamic equilibrium with a slowly cooling nebula. FeO formed and dissolved in the droplets in an initial stage when the nucleation of iron was blocked, and was later mostly reduced to unalloyed Fe. At high temperatures, the silicate droplets contained high concentrations of the less volatile components CaO and Al2O3. At somewhat lower temperatures the equilibrium MgO content of the droplets was relatively high. As cooling progressed, some droplets gravitated toward the Sun, and moved in other directions, depleting the region in CaO, Al2O3, and MgO and accounting for the relatively low observed CaO/SiO2, Al2O3/ SiO2, and MgO/SiO2 ratios in enstatite chondrites. At approximately 1400 K, the remaining supercooled silicate droplets crystallized to form MgSiO3 (enstatite) with small amounts of olivine and a high-SiO2 liquid phase which became the mesostases. The high enstatite content is the result of the supercooled chondrules crystallizing at a relatively low temperature and relatively high total pressure. Finally, FeS formed at temperatures below 680 K by reaction of the condensed Fe with H2S. All calculations were performed with the evaluated optimized thermodynamic databases of the FactSage thermodynamic computer system. The thermodynamic properties of compounds and solutions in these databases were optimized completely independently of any meteoritic data. Agreement of the model with observed bulk and phase compositions of enstatite chondrules is very good and is generally within experimental error limits for all components and phases.
  • Cooling rates of porphyritic olivine chondrules in the Semarkona (LL3.00) ordinary chondrite: A model for diffusional equilibration of olivine during fractional crystallization

    Miyamoto, M.; Mikouchi, T.; Jones, R. H. (The Meteoritical Society, 2009-01-01)
    Cooling rates of chondrules provide important constraints on the formation process of chondrite components at high temperatures. Although many dynamic crystallization experiments have been performed to obtain the cooling rate of chondrules, these only provide a possible range of cooling rates, rather than providing actual measured values from natural chondrules. We have developed a new model to calculate chondrule cooling rates by using the Fe-Mg chemical zoning profile of olivine, considering diffusional modification of zoning profiles as crystals grow by fractional crystallization from a chondrule melt. The model was successfully verified by reproducing the Fe-Mg zoning profiles obtained in dynamic crystallization experiments on analogs for type II chondrules in Semarkona. We applied the model to calculating cooling rates for olivine grains of type II porphyritic olivine chondrules in the Semarkona (LL3.00) ordinary chondrite. Calculated cooling rates show a wide range from 0.7 degrees C/h to 2400 degrees C/h and are broadly consistent with those obtained by dynamic crystallization experiments (10-1000 degrees C/h). Variations in cooling rates in individual chondrules can be attributed to the fact that we modeled grains with different core Fa compositions that are more Fe-rich either because of sectioning effects or because of delayed nucleation. Variations in cooling rates among chondrules suggest that each chondrule formed in different conditions, for example in regions with varying gas density, and assembled in the Semarkona parent body after chondrule formation.
  • Infrared spectroscopy of Wild 2 particle hypervelocity tracks in Stardust aerogel: Evidence for the presence of volatile organics in cometary dust

    Bajt, S.; Sandford, S. A.; Flynn, G. J.; Matrajt, G.; Snead, C. J.; Westphal, A. J.; Bradley, J. P. (The Meteoritical Society, 2009-01-01)
    Infrared spectroscopy maps of some tracks made by cometary dust from 81P/Wild 2 impacting Stardust aerogel reveal an interesting distribution of organic material. Out of six examined tracks, three show presence of volatile organic components possibly injected into the aerogel during particle impacts. When particle tracks contained volatile organic material, they were found to be -CH2- rich, while the aerogel is dominated by the -CH3-rich contaminant. It is clear that the population of cometary particles impacting the Stardust aerogel collectors also includes grains that contained little or none of this organic component. This observation is consistent with the highly heterogeneous nature of collected grains, as seen by a multitude of other analytical techniques.
  • New model calculations for the production rates of cosmogenic nuclides in iron meteorites

    Ammon, K.; Masarik, J.; Leya, I. (The Meteoritical Society, 2009-01-01)
    Here we present the first purely physical model for cosmogenic production rates in iron meteorites with radii from 5 cm to 120 cm and for the outermost 1.3 m of an object having a radius of 10 m. The calculations are based on our current best knowledge of the particle spectra and the cross sections for the relevant nuclear reactions. The model usually describes the production rates for cosmogenic radionuclides within their uncertainties; exceptions are 53Mn and 60Fe, possibly due to normalization problems. When an average S content of about 1 +/- 0.5% is assumed for Grant and Carbo samples, which is consistent with our earlier study, the model predictions for 3He, 21Ne, and 38Ar are in agreement. For 4He the model has to be adjusted by 24%, possibly a result of our rather crude approximation for the primary galactic particles. For reasons not yet understood the modeled 36Ar/38Ar ratio is about 30-40% higher than the ratio typically measured in iron meteorites. Currently, the only reasonable explanation for this discrepancy is the lack of experimentally determined neutron induced cross sections and therefore the uncertainties of the model itself. However, the new model predictions, though not yet perfect, enable determining the radius of the meteoroid, the exposure age, the sulphur content of the studied sample as well as the terrestrial residence time. The determination of exposure ages is of special interest because of the still open question whether the GCR was constant over long time scales. Therefore we will discuss in detail the differences between exposure ages determined with different cosmogenic nuclides. With the new model we can calculate exposure ages that are based on the production rates (cm3 STP/(gMa)) of noble gases only. These exposure ages, referred to as noble gas exposure ages or simply 3,4He , 21Ne , or 36,38Ar ages, are calculated assuming the current GCR flux. Besides calculating noble gas ages we were also able to improve the 41K-40Kand the 36Cl-36Ar dating methods with the new model. Note that we distinguish between 36Ar ages (calculated via 36Ar production rates only) and 36Cl-36Ar ages. Exposure ages for Grant and Carbo, calculated with the revised 41K-40K method, are 628 +/- 30 Ma and 841 +/- 19 Ma, respectively. For Grant this is equal to the ages obtained using 3He, 21Ne, and 38Ar but higher than the 36Ar- and 36Cl- 36Ar ages by ~30%. For Carbo the 41K-40K age is ~40% lower than the ages obtained using 3He, 21Ne, and 38Ar but equal to the 36Ar age. These differences can either be explained by our still insufficient knowledge of the neutron-induced cross sections or by a long-term variation of the GCR.
  • An investigation of the behavior of Cu and Cr during iron meteorite crystallization

    Chabot, N. L.; Saslow, S. A.; McDonough, W. F.; Jones, J. H. (The Meteoritical Society, 2009-01-01)
    The measured Cu and Cr contents in magmatic iron meteorites appear to contradict the behavior predicted by experimental fractional crystallization studies currently available. To investigate the origin of Cu and Cr concentrations observed in these meteorites, a thorough set of solid metal/liquid metal experiments were conducted in the Fe-Ni-S system. In addition to Cu and Cr, partitioning values were also determined for As, Au, Bi, Co, Mo, Ni, Pb, Rh, Ru, Sb, Sn, V, and Zn from the experiments. Experimental results for Cu and Cr showed similar chalcophile partitioning behavior, whereas these elements have differently sloped trends within magmatic iron meteorite groups. Thus, fractional crystallization alone cannot control both the Cu and Cr concentrations in these iron meteorite groups. A simple fractional crystallization model based on our experimental Cu partitioning results was able to match the Cu versus Au trend observed in the S-poor IVB iron meteorite group but not the decreasing Cu versus Au trends in the IIAB and IIIAB groups or the unique S-shaped Cu versus Au trend in the IVA group. However, the crystallization model calculations were found to be very sensitive to the specific choice for the mathematical expression of D(Cu), suggesting that any future refinement of the parameterization of D(Cu) should include a reassessment of the Cu fractional crystallization trends. The Cr versus Au trends in magmatic iron meteorite groups are steeper than those of Cu and not explained by fractional crystallization. Other influences, such as the removal of chromite from the crystallizing system or sampling biases during iron meteorite compositional analyses, are likely responsible for the Cr trends in magmatic iron meteorite groups.