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

QUESTIONS?

Contact the University Libraries Journal Team with questions.

Recent Submissions

  • A model for planetesimal meltdown by 26Al and its implications for meteorite parent bodies

    Hevey, Phonsie J.; Sanders, Ian S. (The Meteoritical Society, 2006-01-01)
    The melting of planetesimals heated by 26Al has been modelled using a new finite difference method that incorporates convection. As an example, we consider a planetesimal with a radius of 64 km, which accretes instantaneously at t = 0.75 Myr (after the formation of calcium-aluminum-rich inclusions) from cold (250 K) nebular dust with 50% porosity. At t = 0.9 Myr (T = 700 K), the planetesimal shrinks to a radius of 50 km due to sintering. At t = 1.2 Myr (T = 1425 K), the fully insulated interior, deeper than a few kilometers, starts to melt, and at t = 1.5 Myr (T = 1725 K), with 50% melting, convection starts. By t = 2 Myr, the planetesimal is a globe of molten, convecting slurry inside a thin residual crust. From about t = 2.5 Myr, the crust thickens rapidly as the power of 26Al fades.Planetesimals probably melt in this manner when they accrete before t = 1.3 Myr and are large enough to insulate themselves (R >20 km for accretion at t = 0, rising to >80 km at t = 1.3 Myr). Melting behavior will also be affected by the level of 60Fe in nebular dust, by the extent of devolatilization reactions and basalt segregation during heating, and by gradual accretion.The model suggests that a) the parent bodies of differentiated meteorites had accreted before about t = 1.5 to 2 Myr and before most chondritic parent bodies had formed, and b) that molten planetesimals may be a source for chondrule melt droplets.
  • Variation of chemical composition in Australasian tektites from different localities in Vietnam

    Amare, Kassa; Koeberl, Christian (The Meteoritical Society, 2006-01-01)
    One hundred and thirteen Australasian tektites from Vietnam (Hanoi, Vinh, Dalat, and Saigon areas) were analyzed for their major and trace element contents. The tektites are either of splash form or Muong Nong-type. The splash-form tektites have SiO2 contents ranging from 69.7 to 76.8 wt%, whereas Muong Nong-type tektites, which are considerably larger than splash-form tektites and have a blocky and chunky appearance, have slightly higher silica contents in thev range of 74-81 wt%. Major-element relationships, such as FeO versus major oxides, Na2O versus K2O, and oxide ratio plots, were used to distinguish the different groups of the tektites. In addition, correlation coefficients have been calculated for each tektite group of this study. Many chemical similarities are noted between Hanoi and Vinh tektites from the north of Vietnam, except that the Hanoi tektites contain higher contents of CaO than Vinh; the higher content of CaO might be due to some carbonate parent material. Both Dalat and Saigon tektites have nearly similar composition, whereas the bulk chemistries of the tektites from Hanoi and Vinh appear different from those of Saigon and Dalat. There are differences, especially in the lower CaO and Na2O and higher MgO, FeO, for the tektites of Dalat and Saigon in comparison to that of Hanoi tektites. Furthermore, the Dalat and Saigon tektites show enrichments by factors of 3 and 2 for the Ni and Cr contents, respectively, compared to those of Hanoi and Vinh. The difference in chemistry between the North Vietnam tektites (Hanoi, Vinh) to that of South Vietnam tektites (Saigon, Dalat) of this study indicate that the parent material was heterogeneous and possibly mixing between different source rocks took place.Muong Nong-type tektites are enriched in the volatile elements such as Br, Zn, As, and Sb compared to the average splash-form tektites of this study. The chemical compositions of the average splash-form and Muong Nong-type tektites of this study closely resemble published data for average splash-form and Muong Nong-type indochinites, indicating that they have the same source. The trace element ratios Ba/Rb (2.7), Th/U (5.2), Th/Sc (1.3), Th/Sm (2.2), and the rare earth element (REE) abundances of this study show close similarities to those of aerageupper continental crust.
  • Shock, post-shock annealing, and post-annealing shock in ureilites

    Rubin, Alan E. (The Meteoritical Society, 2006-01-01)
    The thermal and shock histories of ureilites can be divided into four periods: 1) formation, 2) initial shock, 3) post-shock annealing, and 4) post-annealing shock. Period 1 occurred 4.55 Ga ago when ureilites formed by melting chondritic material. Impact events during period 2 caused silicate darkening, undulose to mosaic extinction in olivines, and the formation of diamond, lonsdaleite, and chaoite from indigenous carbonaceous material. Alkali-rich fine-grained silicates may have been introduced by impact injection into ureilites during this period. About 57% of the ureilites were unchanged after period 2. During period 3 events, impact-induced annealing caused previously mosaicized olivine grains to become aggregates of small unstrained crystals. Some ureilites experienced reduction as FeO at the edges of olivine grains reacted with degrees C from the matrix. Annealing may also be responsible for coarsening of graphite in a few ureilites, forming euhedral-appearing, idioblastic crystals. Orthopyroxene in Meteorite Hills (MET) 78008 may have formed from pigeonite by annealing during this period. The Rb-Sr internal isochron age of ~4.0 Ga for MET 78008 probably dates the annealing event. At this late date, impacts are the only viable heat source. About 36% of ureilites experienced period 3 events, but remained unchanged afterwards. During period 4, ~7% of the ureilites were shocked again, as is evident in the polymict breccia, Elephant Moraine (EET) 83309. This rock contains annealed mosaicized olivine aggregates composed of small individual olivine crystals that exhibit undulose extinction.Ureilites may have formed by impact-melting chondritic material on a primitive body with heterogeneous O isotopes. Plagioclase was preferentially lost from the system due to its low impedance to shock compression. Brief melting and rapid burial minimized the escape of planetary-type noble gases from the ureilitic melts. Incomplete separation of metal from silicates during impact melting left ureilites with relatively high concentrations of trace siderophile elements.
  • Alastair Graham Walter Cameron (1925-2005)

    Consolmagno, Guy; Fegley, Bruce; Kring, David (The Meteoritical Society, 2006-01-01)
  • The orbit and atmospheric trajectory of the Orgueil meteorite from historical records

    Gounelle, Matthieu; Spurný, Pavel; Bland, Philip A. (The Meteoritical Society, 2006-01-01)
    Using visual observations that were reported 140 years ago in the Comptes Rendus de l'Académie des Sciences de Paris, we have determined the atmospheric trajectory and the orbit of the Orgueil meteorite, which fell May 14, 1864, near Montauban, France. Despite the intrinsic uncertainty of visual observations, we were able to calculate a reasonably precise atmospheric trajectory and a moderately precise orbit for the Orgueil meteoroid. The atmosphere entry point was ~70 km high and the meteoroid terminal point was ~20 km high. The calculated luminous path was ~150 km with an entry angle of 20 degrees. These characteristics are broadly similar to that of other meteorites for which the trajectory is known. Five out of six orbital parameters for the Orgueil orbit are well constrained. In particular, the perihelion lies inside the Earth's orbit (q ~0.87 AU), as is expected for an Earth-crossing meteorite, and the orbital plane is close to the ecliptic (i ~0 degrees). The aphelion distance (Q) depends critically on the pre-atmospheric velocity. From the calculated atmospheric path and the fireball duration, which was reported by seven witnesses, we have estimated the pre-atmospheric velocity to be larger than 17.8 km/sec, which corresponds to an aphelion distance Q larger than 5.2 AU, the semi-major axis of Jupiter orbit. These results suggest that Orgueil has an orbit similar to that of Jupiter-family comets (JFCs), although an Halley-type comet cannot be excluded. This is at odds with other meteorites that have an asteroidal origin, but it is compatible with 140 years of data-gathering that has established the very special nature of Orgueil compared to other meteorites. A cometary origin of the Orgueil meteorite does not contradict cosmochemistry data on CI1 chondrites. If CI1 chondrites originate from comets, it implies that comets are much more processed than previously thought and should contain secondary minerals. The forthcoming return of cometary samples by the Stardust mission will provide a unique opportunity to corroborate (or contradict) our hypothesis.
  • Petrographic comparison of refractory inclusions from different chemical groups of chondrites

    Lin, Y.; Kimura, M.; Miao, B.; Dai, D.; Monoi, A. (The Meteoritical Society, 2006-01-01)
    Twenty-four refractory inclusions (40-230 micrometers, with average of 86 +/- 40 micrometers) were found by X-ray mapping of 18 ordinary chondrites. All inclusions are heavily altered, consisting of finegrained feldspathoids, spinel, and Ca-pyroxene with minor ilmenite. The presence of feldspathoids and lack of melilite are due to alteration that took place under oxidizing conditions as indicated by FeO-ZnO-rich spinel and ilmenite. The pre-altered mineral assemblages are dominated by two types: one rich in melilite, referred to as type A-like, and the other rich in spinel, referred to as spinel-pyroxene inclusions. This study and previous data show similar type and size distributions of refractory inclusions in ordinary and enstatite chondrites. A survey of refractory inclusions was also conducted on Allende and Murchison in order to make unbiased comparison with their counterparts in other chondrites. The predominant inclusions are type A and spinel-pyroxene, with average sizes of 170 +/- 130 micrometers (except for two mm-sized inclusions) in Allende and 150 +/- 100 micrometers in Murchison. The relatively larger sizes are partially due to common conglomerating of smaller nodules in both chondrites. The survey reveals closely similar type and size distributions of refractory inclusions in various chondrites, consistent with our previous data of other carbonaceous chondrites. The petrographic observations suggest that refractory inclusions in various groups of chondrites had primarily formed under similar processes and conditions, and were transported to different chondrite-accreting regions. Heterogeneous abundance and distinct alteration assemblages of refractory inclusions from various chondrites could be contributed to transporting processes and secondary reactions under different conditions.
  • Conditions in the protoplanetary disk as seen by the type B CAIs

    Richter, Frank M.; Mendybaev, Ruslan A.; Davis, Andrew M. (The Meteoritical Society, 2006-01-01)
    Type B coarse-grained calcium-aluminum-rich inclusions (CAIs) are the oldest known materials to have formed in the solar system and are a unique source of information regarding conditions and processes in the protoplanetary disk around the young sun. Recent experimental results on the crystallization and evaporation of type B-like silicate melts allow us to place the following constraints on the conditions in the protoplanetary disk during the formation of type B CAIs. 1) Once type B CAIs precursors have been condensed from a solar composition gas, they were reheated at 1250-1450 degrees C, as is indicated by their igneous texture. 2) The melilite mantles characteristic of type B1 CAIs could be formed by crystallization of magnesium- and silicon-depleted melt in the outer part of the partially molten droplets. Such depletion can arise when evaporation is fast compared to chemical diffusion in the melt. This requires the pressure of the surrounding solar composition gas to be at least 10^(-4) bars during the initial crystallization of melilite mantle. Type B2 CAIs with uniform distribution of melilite are expected to form at pressures less than 10^(-5) bars. 3) Evaporation calculations are used to place bounds on the thermal history of the type B CAIs. Observed compositional zoning in melilite suggests that the temperatures in the protoplanetary disk where the type B CAIs resided after crystallization could not have exceeded ~1000 degrees C for more than a few tens of thousands of years. A recent calculation of the physical conditions associated with nebular shocks produced transient temperatures and gas pressures very much like what we find is required to melt reasonable CAI precursors and evaporate these sufficiently quickly to make a type B1 CAI.
  • Maximal size of chondrules in shock wave heating model: Stripping of liquid surface in a hypersonic rarefied gas flow

    Kato, Takaaki; Nakamoto, Taishi; Miura, Hitoshi (The Meteoritical Society, 2006-01-01)
    We examined partially molten dust particles that have a solid core and a surrounding liquid mantle, and estimated the maximal size of chondrules in a framework of the shock wave heating model for chondrule formation. First, we examined the dynamics of the liquid mantle by analytically solving the hydrodynamics equations for a core-mantle structure via a linear approximation. We obtained the deformation, internal flow, pressure distribution in the liquid mantle, and the force acting on the solid core. Using these results, we estimated conditions in which liquid mantle is stripped off from the solid core. We found that when the particle radius is larger than about 1-2 mm, the stripping is expected to take place before the entire dust particle melts. So chondrules larger than about 1-2 mm are not likely to be formed by the shock wave heating mechanism. Also, we found that the stripping of the liquid mantle is more likely to occur than the fission of totally molten particles. Therefore, the maximal size of chondrules may be determined by the stripping of the liquid mantle from the partially molten dust particles in the shock waves. This maximal size is consistent with the sizes of natural chondrules.
  • Oxygen isotope and 26Al-26Mg systematics of aluminum-rich chondrules from unequilibrated enstatite chondrites

    Guan, Yunbin; Huss, Gary R.; Leshin, Laurie A.; MacPherson, Glenn J.; McKeegan, Kevin D. (The Meteoritical Society, 2006-01-01)
    Correlated in situ analyses of the oxygen and magnesium isotopic compositions of aluminum-rich chondrules from unequilibrated enstatite chondrites were obtained using an ion microprobe. Among eleven aluminum-rich chondrules and two plagioclase fragments measured for 26Al-26Mg systematics, only one aluminum-rich chondrule contains excess 26Mg from the in situ decay of 26Al; the inferred initial ratio (26Al/27Al)o = (6.8 +/- 2.4) x 10^(-6) is consistent with ratios observed in chondrules from carbonaceous chondrites and unequilibrated ordinary chondrites.The oxygen isotopic compositions of five aluminum-rich chondrules and one plagioclase fragment define a line of slope ~0.6 +/- 0.1 on a three-oxygen-isotope diagram, overlapping the field defined by ferromagnesian chondrules in enstatite chondrites but extending to more 16O-rich compositions with a range in delta-18O of about ~12 ppm. Based on their oxygen isotopic compositions, aluminum-rich chondrules in unequilibrated enstatite chondrites are probably genetically related to ferromagnesian chondrules and are not simple mixtures of materials from ferromagnesian chondrules and calcium-aluminum-rich inclusions (CAIs).Relative to their counterparts from unequilibrated ordinary chondrites, aluminum-rich chondrules from unequilibrated enstatite chondrites show a narrower oxygen isotopic range and much less resolvable excess 26Mg from the in situ decay of 26Al, probably resulting from higher degrees of equilibration and isotopic exchange during post-crystallization metamorphism. However, the presence of 26Al-bearing chondrules within the primitive ordinary, carbonaceous, and now enstatite chondrites suggests that 26Al was at least approximately homogeneously distributed across the chondrite-forming region.
  • The prospect of high-precision Pb isotopic dating of meteorites

    Amelin, Yuri (The Meteoritical Society, 2006-01-01)
    The radiogenic 207Pb/206Pb ratio is the only extant nuclide chronometer with sufficient time resolution for studies of the solar nebula accretion and early asteroidal differentiation and metamorphism. Pb isotopic dates can be used to link the dates obtained from extinct nuclide chronometers to the absolute time scale. The factors that control precision and accuracy of Pb isotopic dates of meteorites: instrumental mass fractionation in isotopic analysis, mass spectrometer sensitivity, removal of common Pb, multi-stage evolution of U-Pb systems, disturbances caused by diffusion, alteration, and shock metamorphism, and uncertainties in decay constants and the natural ratio of the U isotopes are reviewed. The precision of Pb isotopic dates of meteorites attained with currently available techniques and methodology is +/- 0.5-1.0 Myr in favorable cases. The accuracy of time interval measurements is approximately the same. The most serious limitation on precision and accuracy of Pb isotopic dates is placed by the presence of common Pb of uncertain and/or variable isotopic composition. Improvement in precision and accuracy of Pb isotopic dates would be possible through combined advancement of techniques of isotopic analysis (most importantly, better control over instrumental mass fractionation) and more effective techniques for the removal of common Pb, together with a better understanding of the effects of thermal metamorphism, shock metamorphism, and aqueous alteration on the U-Pb system in meteorites.
  • The I-Xe chronometer and the early solar system

    Gilmour, J. D.; Pravdivtseva, O. V.; Busfield, A.; Hohenberg, C. M. (The Meteoritical Society, 2006-01-01)
    We review the development of the I-Xe technique and how its data are interpreted, and specify the best current practices. Individual mineral phases or components can yield interpretable trends in initial 129I/127I ratio, whereas whole-rock I-Xe ages are often hard to interpret because of the diversity of host phases, many of which are secondary. Varying standardizations in early work require caution; only samples calibrated against Shallowater enstatite or Bjurböle can contribute reliably to the emerging I-Xe chronology of the early solar system.Although sparse, data for which I-Xe and Mn-Cr can be compared suggest that the two systems are concordant among ordinary chondrite samples. We derive a new age for the closure of the Shallowater enstatite standard of 4563.3 +/- 0.4 Myr from the relationship between the I-Xe and Pb-Pb systems. This yields absolute I-Xe ages and allows data from this and other systems to be tested by attempting to construct a common chronology of events in the early solar system.Absolute I-Xe dates for aqueous and igneous processes are consistent with other systems. Consideration of the I-Xe host phases in CAIs and dark inclusions demonstrates that here the chronometer records aqueous alteration of pre-existing material. The ranges of chondrule ages deduced from the Al-Mg and I-Xe systems in Semarkona (LL3.0) and Chainpur (LL3.4) are consistent. Chainpur I-Xe data exhibit a greater range of ages than Semarkona, possibly reflecting a greater degree of parent body processing. However individual chondrules show little or no evidence of such processing. Determining the host phase(s) responsible for high temperature correlations may resolve the issue.
  • Workshop on Chondrites and the Protoplanetary Disk Kaua'i, Hawai'i, 2004

    Liffman, Kurt (The Meteoritical Society, 2006-01-01)