bluuebunny/crossref_metadata_2025 huggingface dataset:
The Jolomba, Angola LL6 chondrite
Authors: Sighinolfi G. Paolo , Garuti Giorgio , Morais Eduardo
Published: June 2012

Abstract— Accompanied by loud thunder at about 1.30 pm (local time) on 3 February 1974, a single stone weighing approx. 480 g was seen to fall and was recovered near the Jolomba village, Huambo District, Angola. The stone is strongly brecciated, has dark‐greyish angular fragments within a lighter matrix and does not exhibit any chondritic textures. Jolomba consists of olivine (Fa 31), orthopyroxene (Fs 25), sodic plagioclase (An 11), sulphides (troilite), very scarce nickel‐iron (Ni up to 56%), oxides (chromite and ilmenite) and apatite. Pervasive fracturing of silicates suggests that Jolomba suffered strong brecciation and partial recrystallization. Mineralogy and bulk chemical analysis indicate that Jolomba belongs to the LL group of chondrites (amphoterites). Uniform olivine and pyroxene composition, well‐crystallized plagioclase and textural features in general indicate that Jolomba belongs to the petrologic type 6.
Fluorine and boron geochemistry of tektites, impact glasses, and target rocks
Authors: Matthies Dietmar , Koeberl Christian
Published: June 2012

Abstract— We have analyzed fluorine and boron in nine tektites from all four strewn fields, and in a suite of impact glasses and target rocks from the Zhamanshin and Darwin impact craters, as well as Libyan Desert Glass and Aouelloul impact glass samples. Fluorine and boron are useful indicators for the volatilization and temperature history of tektites and impact glasses. Tektites from different strewn fields show a limited range of F and B contents and have F/B ratios near unity. Most splash‐form tektites have lower average F and B contents than Muong Nong type tektites, which is similar to the relation between irghizites and zhamanshinites. The F and B contents in target rocks from the Zhamanshin and Darwin impact craters are similar to normal terrestrial sediments. Fluorine in impact glasses and tektites is more depleted compared to their (known or inferred) target rocks than is boron, which is caused by the higher volatility of F. The F/B ratios therefore decrease with increasing temperature of formation (suggesting that irghizites were formed at a higher temperature than zhamanshinites, and Muong Nong type tektites at a lower temperature than splash‐form tektites). Mixing of local country rocks together with partial loss of the volatiles F and B can reproduce the F and B contents of impact glasses.
A shallow seismic refraction study of the Versailles cryptoexplosion structure, central Kentucky
Authors: Harris James B. , Jones Daniel R. , Street R. L.
Published: June 2012

Abstract— The Versailles cryptoexplosion structure, located in central Kentucky, contains a partially brecciated central uplift and a boundary marked by arcuate faulting. Seismic refraction data were used to divide the structure into distinct units on the basis of velocity. A zone of brecciated material shows a decrease in velocity compared with surrounding rocks. Locally thickened strata are present on the flanks of the central uplift. An increase of the bedrock velocity in the area surrounding the structure suggests localized dolomization of fractured bedrock, and a plug of fractured strata near the base of the brecciation appears to be uplifted. Based on the geometry of deformation seen in known impact structures, and the integration of this study with previous geological and geophysical work in the area, it is suggested that our results support the interpretation of the Versailles structure as an eroded astrobleme (Black, 1964b; Seeger, 1972).
The Bencubbin stony‐iron meteorite breccia: Electron petrography, shock‐history and affinities of a “carbonaceous chondrite” clast
Authors: Barber D. J. , Hutchison R.
Published: June 2012

Abstract— A “carbonaceous chondrite” clast from Bencubbin was studied by analytical transmission electron microscopy and other electron beam techniques. In section, the clast consists of oval augen, with a preferred orientation, set in fine‐grained matrix. The augen comprise olivine microphenocrysts in fine‐grained to glassy mesostases. The olivines are heavily deformed, giving rise to mosaicism. Many sub‐grains have high densities of dislocations with [001] Burgers vectors. In some regions the dislocation configurations are recovered, causing a reduced dislocation density; recrystallization is rarer. Severe cataclasis is absent; there are few open fractures and little intergranular porosity except where a second phase occurs. Such porosity in olivine mainly occurs as finescale negative crystals, which appear to be healed cracks. Some mesostases consist of small amounts of microporous oxides and feldspathic glass but glassy veins are absent. Pyrhottite and Fe/Ni sulfides are major mesostasis constituents that rarely form tongues between the olivines, which commonly include smaller sulfide blebs.

The matrix of the clast has abundant sulfides and fine‐grained, poorly crystalline Fe‐ and Fe/Ni‐oxides, with more sparse ferrihydrite. The oxides mostly occur in contact with, or within, aluminous and siliceous glassy material in which crystals of melilite, spinel, Ca‐pyroxene, feldspar, and other minor silicate phases have grown. Small patches of fibrous and/or sheet‐like Mg/Fe silicates with layer morphologies also occur. They are microporous, poorly crystalline and lack the layer spacings of phyllosilicates, of which they may be relics. Grains of anhydrite and calcite are interlaced with fibrous silicates.

There is evidence that one, or more, intense shock‐heating event(s) produced local melting. A later shock event(s) involved less severe shock‐heating, to about 900 °C. The mineralogy indicates that the clast may have originated from a CM2 precursor or from material like Allan Hills 85085, although it is just possible that terrestrial weathering produced some of the diagnostic minerals.
Transmission electron microscopy of a refractory inclusion from the Allende meteorite: Anatomy of a pyroxene
Authors: Doukhan N. , Doukhan J. C. , Poirier J. P.
Published: June 2012

Abstract— A crystal of clinopyroxene from the coarse‐grained refractory inclusion Egg 6 of the Allende meteorite has been studied in detail by transmission electron microscopy.

The pyroxene crystal contains euhedral, dislocation‐free inclusions of pure spinel MgAl2O4, without any topotactic relation to the host. Extensive dislocation walls at equilibrium, characteristic of high‐temperature anneal, are present in the crystal. Alteration products are occasionally observed at the spinel‐pyroxene interface close to regions where dislocation walls decorated with bubbles (or voids) are present. The bubbles, often in the shape of tubes along the dislocation lines, are thought to be due to the precipitation of a fluid migrating along the dislocations.

The observations are compatible with crystallization of the refractory inclusions from the melt and with the existence of a later stage of metasomatism.
Mineralogy of interstitial rim materials of the Y74123 and Y790981 ureilites and their origin
Authors: Ogata Hiromi , Hiroshi Mori  , Takeda Hiroshi
Published: June 2012

Abstract— Y74123 is an olivine‐rich, relatively unshocked ureilite and contains more interstitial pigeonitic materials than do ureilites which have been reported previously. Thus, Y74123 is especially suited for detailed study of the interstitial materials. We have studied these materials by optical microscope, electron microprobe, scanning electron microscope, high resolution transmission electron microscope (TEM) and analytical TEM to gain a better understanding of their nature and origin. Y790981, with shock partial melts, has also been examined by the same techniques. Bulk chemical compositions of the interstitial materials in Y74123 are pyroxene‐like and have higher CaO and Al2O3 contents than the large pigeonite and olivine core. Interstitial materials at olivine‐pigeonite grain boundaries are richer in CaO and Al2O3 than those at olivine‐olivine grain boundaries. TEM observations of the interstitial material of Y74123 show that it consists of alternating pigeonite‐augite lamellae more than 3.5 μm thick on (001). This texture suggests that the rim material had already crystallized before the parent body breakup. The shock‐produced glassy veins in Y790981 cut through the rim materials. These observations are consistent with the idea that the interstitial materials in this ureilite are a mixture of residual liquids of high Ca melts and shock‐produced partial melts of olivine and pigeonite. This mixture accumulated along the grain boundaries and some of it is trapped within grains.
Further finds of the Derrick Peak meteorite, Transantarctic Mountains, and implications for terrestrial age
Authors: Kirkbride Martin P. , Bradshaw Margaret A. , Harmsen Fraka J.
Published: June 2012

Abstract— Nine additional iron meteorite fragments weighing a total of 72 kg were recovered from the Derrick Peak area by a Canterbury Museum geological party in late 1988. One iron was located in the Onnum Valley, 6 km south of the previous finds. Geochemical analysis indicates that all irons belong to a single meteorite shower, greatly increasing the known extent of the fall zone. Kamp and Lowe (1982) have previously estimated the terrestrial age of the meteorite from glacial geological evidence. The location of the 1988 finds supports Kamp and Lowe's interpretation that the meteorites lie in situ, but recent revisions of the chronology of Cenozoic glacial history of the region reduce the interpreted terrestrial age. An age of between Oxygen Isotope stages 6 and 2 is probable (190–125 to 35–12 ka BP). This conflicts with a terrestrial age estimate of 1.0 ± 0.1 Ma BP from cosmogenic radionuclides.
On the production of cosmogenic nuclides in meteoroids by galactic protons
Authors: Michel R. , Dragovitsch P. , Cloth P. , Dagge G. , Filges D.
Published: June 2012

Abstract— A purely physical model is presented describing the depth‐ and size‐dependence of the production of cosmogenic nuclides in meteoroids with radii up to 85 cm and in planetary surfaces by galactic cosmic ray protons. The model is based on Monte Carlo calculations of the intra‐ and internuclear cascades, by which depth‐ and size‐dependent spectra of primary and secondary protons and of secondary neutrons are derived, and on experimental and theoretical thin‐target cross sections of the underlying nuclear reactions. Model calculations are presented for production rates of 53Mn, 26Al, 22Ne, and 21Ne in H‐ and L‐chondrites and of 53Mn and 26Al in lunar surface material and compared with experimental data. From the analysis of 53Mn and 26Al in the Apollo 15 lunar drill core and in the L‐chondrite Knyahinya GCR p‐spectra and integral particle fluxes at 1 A.U. and in the meteoroid orbits averaged over the last 10 Ma are derived. An analysis of experimental depth profiles in four H‐ and L‐chondrites demonstrates, that the new model is well capable of describing depth‐ and size‐dependences of production rates of cosmogenic nuclides. Moreover, it is possible to determine exposure ages for these meteorites on the basis of the theoretical 21Ne production rates. The model calculations further explain the depth‐ and size‐dependence of 22Ne/21Ne‐ratios and the dependences on these ratios of 21Ne, 26Al and 53Mn production rates. The future requirements for model calculations of cosmogenic nuclide production rates in extraterrestrial matter are outlined.
Heavy‐element abundances from a neutron burst that produces Xe‐H
Authors: Howard W. Michael , Meyer Bradley S. , Clayton Donald D.
Published: June 2012

Abstract— We examine quantitatively the suggestion that the heavy anomalous isotopes of Xe‐HL found in meteoritic diamonds were produced by a short intense neutron burst and then implanted into the diamonds. Using a large nuclear reaction network we establish one (out of many) neutron irradiation histories that successfully reproduces the heavy isotopes of Xe‐HL, and then evaluate what that same history would produce in every heavy element. This has become more relevant following recent measurement of anomalous Ba and Sr in those same diamond samples. Therefore we offer these calculations as a guide to the anomalies to be expected in all elements if this scenario is correct. We also discuss several other aspects of the problem, especially the established contradictions for Ba, the observed Kr pattern, the near normalcy of 129Xe, and some related astrophysical ideas. In particular we argue from p‐process theory that the observed deficit of 78Kr in correlation with 124–126Xe excess implicates Type II supernovae as the diamond sources. However, our more complete astrophysical conclusions will be published elsewhere. This present work is offered as computational expectation for this class of models and as a guide to considerations that may accelerate the digestion of new experimental results in the diamonds.
The Dengli H3 complex breccia: A 1976 find from the Karakoom Desert
Authors: Ivanova M. A. , Zaslavskay N. I. , Kononkova N. N.
Published: June 2012

Abstract— Dengli is a highly weathered 243.5‐g chondrite that was found in 1976 in the Karakoom desert, Turkmenia. The meteorite contains olivine, high‐Ca and low‐Ca twinned pyroxenes, plagioclase, merrillite, cryptocrystalline material, and opaque minerals: metallic Fe, Ni, troilite, chromite. Based on the texture and the compositions of olivine (Fa19.6, n = 52, C.V. = 19.3) and low‐Ca pyroxene (Fs18.2, n = 27, C.V. = 17.0), Dengli is classified as an H3.8 breccia.
The Sychevka IIIAB iron meteorite: A new find from Russia
Authors: Krot Alexander N. , Zaslavskay Nina I. , Petaev Michail I. , Kononkova Natalya N. , Kolesov Gennady M. , Barsukova Lydia D.
Published: June 2012

Abstract— Sychevka is a relatively unweathered 65‐kg iron meteorite that was found in Russia in 1988. The microstructure, mineralogy and bulk composition of Sychevka as revealed by optical microscopy, electron microprobe and instrumental neutron activation analysis indicate that this meteorite is a group‐IIIAB medium octahedrite. Sychevka consists of (in vol%): kamacite (82.5), plessite (16), schreibersite (1.5), and rare grains of chromite and troilite.
Classification of four ordinary chondrites from the Monnig Meteorite Collection
Authors: Ehlmann Arthur J. , Keil Klaus
Published: June 2012

Abstract— We classified four ordinary chondrites from the Monnig Meteorite Collection into compositional groups, petrologic types and shock stages, based on optical microscopy in transmitted and reflected light, and electron microprobe and modal analyses. These meteorites are Allen, Texas, H4(S2); May Day, Kansas, H4(S2); Pony Creek, Texas, H4(S3); and Springer, Oklahoma, H5(S3).
The Hashima, Japan H4 chondrite: A newly reported meteorite
Authors: Hoshino Mitsuo , Suwa Kanenori
Published: June 2012

Abstract We report a new chondrite that fell in Hashima City in central Japan sometime during the period 1868–1912. The chondrite weighs 1110.64 g and exhibits distinct chondritic structure. Chondrules occupy 24 vol% of the stone and consist of olivine (average Fa17,8), low‐Ca pyroxene (average Fs15,8 Wo0.9), devitrified glass and lesser amounts of oligoclase (ca. Ab80Or4), kamacite, taenite, troilite and chromian spinel. Matrix occupying 76 vol% of the stone consists of olivine, low‐Ca pyroxene, kamacite, taenite, troilite, cryptocrystalline minerals and lesser amounts of chromian spinel and chlorapatite. Matrix minerals have the same compositions as those in chondrules.

Mineral chemistry, bulk chemistry and magnetic properties indicate that Hashima is an H‐group chondrite. Well‐defined chondrules, scarcely recrystallized oligoclase and relatively small variations of olivine and low‐Ca pyroxene compositions indicate that Hashima is of petrologic type 4.
Inventory of the meteorite collection of Muséum d'Histoire Naturelle, Geneva, Switzerland
Authors: Dominik B. , Deferne J.
Published: June 2012

Abstract The first inventory of the meteorite collection of the Muséum d'Histoire Naturelle of Geneva is given. The collection, which was initiated early in the nineteenth century and thus is one of the oldest in the world, numbers at present 164 fragments of 102 individual meteorites including the largest fragment (22 kg) of the North Chile hexahedrite. During 1991 the collection was updated and several new specimens were acquired.
Maralinga, a metamorphosed carbonaceous chondrite found in Australia
Authors: Keller Lindsay P. , Clark James C. , Lewis Charles F. , Moore Carleton B.
Published: June 2012

Abstract— The Maralinga meteorite was found near the village of Maralinga, South Australia (30°18′S, 131°16′E) in 1974, but was not recognized as a meteorite until 1989. One weathered individual was recovered with a total mass of 3.38 kg. The bulk composition and petrography of Maralinga indicate that it is a metamorphosed (petrographic type 4) carbonaceous chondrite with major similarities to the Vigarano‐subtype. However, recent trace element data from the literature suggest that Maralinga should be included with the CK (Karoonda‐type) carbonaceous chondrites. We classify Maralinga as an anomalous CK4 chondrite because of its abundant chondrules and refractory inclusions relative to other known members of the CK group. Maralinga contains homogeneous silicates, including Ni‐bearing olivines (Fa34), high‐Ca clinopyroxene, and rare orthopyroxene. Plagioclase is chemically heterogeneous and falls into two distinct compositional groups one of ∼ An20 and an ∼ An80 group. Highly oxidizing conditions during metamorphism of Maralinga are indicated by the abundance of magnetite and the paucity of Fe‐Ni metal.
Tektite‐like bodies at Lonar Crater, India? Very unlikely.
Authors: Fudali R. F. , Fredriksson K.
Published: June 2012

Abstract— The “tektite‐like bodies” reported recently from Lonar Crater, India (Murali et al., 1987) are, in fact, high sodium (up to 22% Na2O) artificial glasses and so need not be explained by unrealistic, natural mixing models. These bodies have no bearing on the problem of impactite chemistry or tektite generation.
A magnetic study of the Millbillillie (eucrite) achondrite: Evidence for a dynamo‐type magnetising field
Authors: Morden S. J.
Published: June 2012

Abstract— The magnetic properties of the Millbillillie eucrite have been intensively studied using mutually oriented samples. The magnetic carrier has been identified as single domain/pseudo‐single domain kamacite. It is believed that due to clast‐rich/clast‐poor layering, the rock has been subjected to minimum shock since formation. This is supported by the presence of a stable, unidirectional remanence. Three separate palaeointensity tests (IRM/NRM, ARM‐NRM, and Thellier heating) have been used to determine the strength of the palaeofield. The criteria for the suitability of samples to be used in such tests are discussed, as are the three methods; IRM/NRM is deemed the least accurate. The results obtained (IRM/NRM: 6 μT and 25 μT; ARM‐NRM: 31 μT, 28 μT, and 15 μT; Thellier: 30 μT, 37 μT, 15 μT) indicate that the rock cooled in a strong magnetic field. Modes of formation, given that Millbillillie has a layered structure, and the nature of the HED parent body, are discussed. A volcanic genesis is preferred over formation in an impact melt. An internal dynamo field is favoured for dynamical reasons, and calculations based on the assumption that 4 Vesta is a possible HED parent body indicate that an iron core may be present in such a body.
40Ar‐39Ar dating of the H3 chondrite Sainte Rose
Authors: Stephan Thomas , Jessberger Elmar K.
Published: June 2012

Abstract— A whole rock sample from the H3 chondrite Sainte Rose, which was discovered in 1983, was dated with the 40Ar‐39Ar technique. From the K/Ca spectrum and from an analysis of the 39Ar recoil effect we conclude that this meteorite has at least two distinguishable K‐carriers: a low temperature, high‐K/Ca, fine‐grained carrier with a typical grain size of about 2 μm and a high temperature, low‐K/Ca, more coarse‐grained carrier. The K‐Ar clocks of both were started 4.40 ± 0.01 Ga ago.
A 10.8‐kg layered (Muong‐Nong‐type) tektite from Wenchang, Hainan, China
Authors: Futrell Darryl S. , Wasson John T.
Published: June 2012

Abstract— A 10.79‐kg layered tektite from Hainan is the largest tektite from China, and the fifth largest reported to date. It together with a 1.9‐kg Hainan tektite described by Yuan (1981) greatly extends the area of the Australasian field within which layered tektites having masses > 1 kg have been found.
Ureilite smelting
Authors: Walker David , Grove Tim
Published: June 2012

Abstract— Ureilites containing homogeneous Fo76 olivine cores in intimate co‐existence with graphite must have recrystallized at pressures of at least ∼100 bars to suppress smelting of the fayalite component of the olivine to Fe metal. Smelting of olivine and pyroxene‐saturated magmatic liquids produces orthopyroxene‐without‐olivine crystalline derivatives unlike those in ureilites. Thus the Mg# compositional variation within the ureilite suite, which is commonly attributed to partial smelting, cannot plausibly be produced by assemblages rich in liquid. In situ smelting of graphitic olivine + pigeonite crystal mushes can produce the correct crystal assemblage, but fails to provide a plausible account for the removal of metal from ureilites or for the correlation of Mg# with Δ17O. Even if Mg# and Δ17O variations are established in the nebula, ureilite recrystallization with graphite must have occurred at pressures greater than the minima we have experimentally established, corresponding to parent objects not less than ∼100 km in radius.
Nitrogen and noble gases in a glass sample from the LEW88516 shergottite
Authors: Becker Richard H. , Pepin Robert O.
Published: June 2012

Abstract— A glass separate from the LEW88516 shergottite was analyzed by step‐wise combustion for N and noble gases to determine whether it contained trapped gas similar in composition to the martian atmosphere‐like component previously observed in lithology C of EETA79001. Excesses of 40Ar and 129Xe were in fact observed in this glass, although the amounts of these excesses are ≤20% of those seen in the latter meteorite, and are comparable to the amounts seen in whole‐rock analyses of LEW88516. The isotopic composition of N in LEW88516 does not show an enrichment in 15N commensurate with the amount of isotopically‐heavy N expected from the noble gases excesses. One must posit some extreme assumptions about the nature of the N components present in LEW88516 in order to allow the presence of the trapped nitrogen component. Alternatively, the N has somehow been decoupled from the noble gases, and was either never present or has been lost.
Unusual dark clasts in the Vigarano CV3 carbonaceous chondrite: Record of parent body process
Authors: Kojima Tomoko , Tomeoka Kazushige , Takeda Hiroshi
Published: June 2012

Abstract— Two unusual dark clasts found in the Vigarano CV3 chondrite were examined using an optical microscope and a scanning electron microscope (SEM). Both clasts lack chondrules, Ca‐Al‐rich inclusions, and coarse‐grained mineral fragments; they, instead, contain abundant inclusions that consist of fine grains (<1 μm) of homogeneous Fe‐rich olivine, thus resembling the fine‐grained variety of dark inclusions in CV3 chondrites. The external shapes of inclusions in the clasts bear a close resemblance to those of chondrules and chondrule fragments; some of the inclusions are surrounded by dark rims similar to chondrule rims. Our SEM observations reveal the following unusual characteristics: 1) the inclusions are not mere random aggregates of olivine grains but have peculiar internal textures, that is, assemblages of round or oval shaped outlines, which are suggestive of pseudomorphs after porphyritic olivine chondrules; 2) one of thick inclusion rims contains a network of vein‐like strings of elongated olivine grains; 3) an Fe‐Ni metal aggregate in one of the clasts has an Fe‐, Ni‐, S‐rich halo suggesting a reaction between its precursor and the surrounding matrix; and 4) olivine in the clasts commonly shows a swirly, fibrous texture similar to that of phyllosilicate. These characteristics suggest that the dark clasts in Vigarano are not primary aggregates of dust in the solar nebula but were affected by aqueous alteration and subsequent dehydration by heating after accretion to the meteorite parent body. The fine olivine grains in these clasts were presumably produced by thermal transformation of phyllosilicate, as is the case with those in the two thermally metamorphosed Antarctic CM chondrites, Belgica‐7904 and Yamato‐86720. From textural and mineralogical similarities, some of the dark inclusions and clasts previously reported from CV3 chondrites and other types of meteorites may have origins common with these clasts in Vigarano.
First occurrence of pyrophanite (MnTi03) and baddeleyite (ZrO2) in an ordinary chondrite
Authors: Krot Alexander N. , Rubin Alan E. , Kononkova Natalya N.
Published: June 2012

Abstract A 220 × 430 μm Mg‐Al‐chromite fragment in the Raguli H3.8 ordinary chondrite exhibits distinct optical and compositional zoning. The dark central region of the Mg‐Al‐chromite is enriched in MgO, Al2O3 and ZnO and depleted in TiO2, Cr2O3, FeO and MnO relative to the lighter outer region. A subhedral olivine grain attached to radiating euhedral ilmenites is present in the central region of the fragment. One of the ilmenite crystals contains a tiny grain (0.5 × 5.8 μm) of baddeleyite (ZrO2). Two end‐member pyrophanite grains (MnTiO3) occur in the outer portion of the fragment This is the first occurrence of pyrophanite and baddeleyite in an ordinary chondrite. Although it is possible that the Mg‐Al‐chromite fragment was derived from an achondritic projectile of unusual composition, we offer two alternative models for its formation. These include (a) a multi‐stage process involving nebular melting of a chromian‐spinel chondrule that had accreted some olivine‐bearing, Mn‐rich material followed by metamorphism on the parent body, and (b) formation of the fragment on a metamorphosed parent body from an impact melt of a chromite‐rich assemblage containing Mn‐rich ilmenite. We favor the latter alternative.
Search for isotopic anomalies in oldhamite (CaS) from unequilibrated (E3) enstatite chondrites
Authors: Lundberg Laura L. , Zinner Ernst , Crozaz Ghislaine
Published: June 2012

Abstract— The Ca isotopic compositions of 32 oldhamite (CaS) grains from the Qingzhen (EH3), MAC88136 (EL3), and Indarch (EH4) enstatite chondrites were determined by ion microprobe mass spectrometry. Also measured were the S isotopic compositions of eight oldhamite, two niningerite (MgS), and seven troilite (FeS) grains. The S isotopic compositions of all minerals are normal, but oldhamite grains of the first two meteorites exhibit apparent small 48Ca excesses and deficits that are correlated with isotopic mass fractionation as determined from the 40Ca‐44Ca pair. The interpretation of these results is complicated by the fact that none of the established mass fractionation laws can account for the data in the Norton County oldhamite standard. The method of analysis is carefully scrutinized for experimental artifacts. Neither interferences nor any known mass fractionation effect can satisfactorily explain the observed small deviations from normal isotopic composition. If these are truly isotopic anomalies, they are much smaller than those observed in hibonite. The nucleosynthetic origin of Ca isotopes is discussed.
Petrofabric examination of the main suevite of the Otting Quarry, Nördlinger Ries, Germany
Authors: Bringemeier Detlef
Published: June 2012

Abstract— Extensive textural studies have been carried out at the suevite in a quarry several kilometers east of the rim of the Nördlinger Ries crater. The composition, grain size and clast orientation of suevite on a 6 m high vertical section were quantified macroscopicaily, as well as microscopically. There exists a strong correlation between the texture of a clastic rock and the transport mechanism of its components. This correlation can be used to obtain information about the transport mechanism of the suevite components, which is fundamental to the understanding of the impact process. A consolidated main suevite enriched in “Flädle” and “Bomben” can be distinguished from a poorly consolidated base suevite, deprived of “Fädle” but relatively well sorted in clast grains. It has been proven that the glass clasts in the main suevite exhibit an inverse gradation, while the crystalline clasts in the lower half of the section show a normal gradation. Eighty one percent of the samples investigated possess orientated clasts ≥2 mm. From the results of this investigation, a predominantly horizontal transport of the main suevite is indicated for the area of investigation. This transport could occur in the form of a suevitie flow similar to that of a pyroclastic flow.
The Divnoe meteorite: Petrology, chemistry, oxygen isotopes and origin
Authors: Petaev M. I. , Barsukova L. D. , Lipschutz M. E. , Wang M.‐S. , Ariskin A. A. , Clayton R. N. , Mayeda T. K.
Published: June 2012

Abstract— The Divnoe meteorite is an olivine‐rich primitive achondrite with subchondritic chemistry and mineralogy. It has a granoblastic, coarse‐grained, olivine groundmass (CGL: coarse‐grained lithology) with relatively large pyroxene‐plagioclase poikilitic patches (PP) and small fine‐grained domains of an opaque‐rich lithology (ORL). Both PP and ORL are inhomogeneously distributed and display reaction boundaries with the groundmass. Major silicates, olivine (Fa20–28) and orthopyroxene (Fs20–28 Wo0.5–2.5), display systematic differences in composition between CGL and ORL as well as a complicated pattern of variations within CGL. Accessory plagioclase has low K content and displays regular igneous zoning with core compositions An40–45 and rims An32–37. The bulk chemical composition of Divnoe is similar to that of olivine‐rich primitive achondrites, except for a depletion of incompatible elements and minor enrichment of refractory siderophiles. Oxygen isotope compositions for whole‐rock and separated minerals from Divnoe fall in a narrow range, with mean δ18O = +4.91, δ17O = +2.24, and Δ17O = −0.26 ± 0.11. The isotopic composition is not within the range of any previously recognized group but is very close to that of the brachinites. To understand the origin of Divnoe lithologies, partial melting and crystallization were modelled using starting compositions equal to that of Divnoe and some chondritic meteorites. It was found that the Divnoe composition could be derived from a chondritic source region by ∼20 wt% partial melting at T ∼ 1300 °C and log(fO2) = IW‐1.8, followed by ∼60 wt% crystallization of the partial melt formed, and removal of the still‐liquid portion of the partial melt. Removal of the last partial melt resulted in depletion of the Divnoe plagioclase in Na and K. In this scenario, CGL represents the residue of partial melting, and PP is a portion of the partial melt that crystallized in situ. The ORL was formed during the final stages of partial melting by reaction between gaseous sulfur and residual olivine in the source region.

A prominent feature of Divnoe is fine μm‐scale chemical variations within olivine grains, related to lamellar structures the olivines display. The origin of these structures is not known.
The Yarle Lakes 001 meteorite: A H5 chondrite from South Australia
Authors: Zbik Marek
Published: June 2012

Abstract— The Yarle Lakes 001 meteorite was a single stone of 913 g found approximately 20 km north of Watson, South Australia, in 1990 October. It consists of olivine (Fa18.7 ± 0.4, n = 30), low‐Ca pyroxene (Fs16.6 ± 0.2 Wo 12 + 0.4, n = 15). feldspar, high‐Ca pyroxene, metallic Fe‐Ni and troilite. Based on texture and mineral chemistry, Yarle Lakes 001 is classified as a H5 chondrite of shock stage S3.
The Mbale meteorite shower
Authors: Jenniskens Peter , Betlem Hans , Betlem Jan , Barifaijo Erasmus , Schlüter Thomas , Hampton Craig , Laubenstein Matthias , Kunz Joachim , Heusser Gerd
Published: June 2012

Abstract— On 1992 August 14 at 12:40 UTC, an ordinary chondrite of type L5/6 entered the atmosphere over Mbale, Uganda, broke up, and caused a strewn field of size 3 × 7 km. Shortly after the fall, an expedition gathered eye witness accounts and located the position of 48 impacts of masses between 0.1 g and 27.4 kg. Short‐lived radionuclide data were measured for two specimens, one of which was only 12 days after the fall. Subsequent recoveries of fragements has resulted in a total of 863 mass estimates by 1993 October. The surfaces of all fragments contain fusion crust. The meteorite shower caused some minor inconveniences. Most remarkably, a young boy was hit on the head by a small specimen.

The data are interpreted as to indicate that the meteorite had an initial mass between 400–1000 kg (most likely ∼1000 kg) and approached Mbale from Az = 185 ± 15, H = 55 ± 15, and V∞ = 13.5 ± 1.5/s. Orbital elements are given. Fragmentation of the initial mass started probably above 25 km altitude, but the final catastrophic breakup occurred at an altitude of 10–14 km. An estimated 190 ± 40 kg reached the Earth's surface minutes after the final breakup of which 150 kg of material has been recovered.
Compositional variations of olivines and pyroxenes in chondritic interplanetary dust particles
Authors: Zolensky Michael E. , Barrett Ruth A.
Published: June 2012

Abstract We report here analyses of olivines and pyroxenes, and petrofabrics of 27 chondritic interplanetary dust particles (IDPs), comparing those from anhydrous and hydrous types. Approximately 40% of the hydrous particles contain diopside, a probable indicator of parent body thermal metamorphism, while this mineral is rarely present in the anhydrous particles. Based on this evidence, we find that hydrous and anhydrous IDPs are, in general, not directly related, and we conclude that olivine and pyroxene major‐element compositions can be used to help discriminate between IDPs that are (1) predominantly nebular condensates, and lately resided in anhydrous or icy (no liquids) primitive parent bodies, and (2) those originating from more geochemically active parent bodies (probably hydrous and anhydrous asteroids).
Equilibration temperatures of EL chondrites: A major downward revision in the ferrosilite contents of enstatite
Authors: Wasson John T. , Kallemeyn Gregory W. , Rubin Alan E.
Published: June 2012

Abstract A study of enstatite grains separated from EL6 chondrites shows ferrosilite contents to be ∼0.02–0.04 mol%, about an order of magnitude lower than reported in the literature. The higher values reported earlier can probably be attributed to the excitation of Fe atoms in Fe‐Ni and FeS, in part from μm‐sized blebs of FeS and Fe‐Ni commonly present in enstatite grains but mainly from large neighboring opaque grains excited by bremsstrahlung or by doubly backscattered electrons. Our EL6 ferrosilite contents are similar to those observed in coarse enstatite grains in some aubrites.

The equilibrium between ferrosilite and Si‐bearing kamacite is highly temperature dependent. At constant Si concentration in kamacite, the equilibrium ferrosilite mole fraction drops by a factor of roughly 2.5 for each 100 K decrease in the equilibrium temperature. As a result, the compositions of these two most common EL6 phases can be used to estimate metamorphic equilibration temperatures. The inferred temperatures are near 1200 K.
A new titanium‐bearing calcium aluminosilicate phase: III. Crystals from a mixer furnace slag
Authors: Barber David J. , Agrell Stuart O.
Published: June 2012

Abstract Small crystals of an optically uniaxial Ti‐bearing calcium aluminosilicate were discovered in a mixer furnace slag consisting mostly of åkermanitic melilite. The crystals have the same unit cell as those observed for a phase crystallized from slowly‐cooled melts used to simulate the formation of aluminous inclusions in meteorites. Moreover, compositions of synthetic and meteoritic occurrences of the phase are all very similar and can be expressed in terms of a binary solid solution between the end‐members Ca3TiAl2Si3O14 and Ca3Ti(AlTi)(AlSi2)O14. Thus, crystallographic and crystallochemical information obtained from crystals in the mixer furnace slag can be used to constrain the origin of similar crystals found in meteoritic inclusions. We separated crystals from the mixer furnace slag by acid leaching; some were used for EPMA analysis, others were crushed for study by TEM methods or X‐ray powder diffraction. Convergent beam electron diffraction shows that the crystals belong to the trigonal (rhombohedral) class and have point group symmetry 3m. X‐ray powder diffraction gives the unit cell parameters a = 0.791 ± 0.009 nm, c = 0.492 ± 0.006 nm. The results suggest that the mineral has space group symmetry P3ml or P31m.
The Chervettaz (L5) meteorite
Authors: Dominik B. , Bussy F. , Meisser N.
Published: June 2012

Abstract The Chervettaz meteorite was an observed fall on 1901 November 30. Our study confirms the previous classification as an L5 chondrite. Weak deformations indicate stage S3 of shock deformations.
Silica‐merrihueite/roedderite‐bearing chondrules and clasts in ordinary chondrites: New occurrences and possible origin
Authors: Krot Alexander N. , Wasson John T.
Published: June 2012

Abstract Merrihueite (K,Na)2(Fe, Mg)5Si12O30 (na < 0.5, fe > 0.5, where na = Na/(Na + K), fe = Fe/(Fe + Mg) in atomic ratio) is a rare mineral described only in several chondrules and irregularly‐shaped fragments in the Mezö‐Madaras L3 chondrite (Dodd et al., 1965; Wood and Holmberg, 1994). Roedderite (Na,K)2(Mg, Fe)5Si12O30 (na > 0.5, fe < 0.5) has been found only in enstatite chondrites and in the reduced, subchondritic silicate inclusions in IAB irons (Fuchs, 1966; Rambaldi et al., 1984; Olsen, 1967). We describe silica‐roedderite‐bearing clasts in L/LL3.5 ALHA77011 and LL3.7 ALHA77278, a silica‐roedderite‐bearing chondrule in L3 Mezö‐Madaras, and a silica‐merrihueite‐bearing chondrule in L/LL3.5 ALHA77115. The findings of merrihueite and roedderite in ALHA77011, ALHA77115, ALHA77278 and Mezö‐Madaras fill the compositional gap between previously described roedderite in enstatite chondrites and silicate inclusions in IAB irons and merrihueite in Mezö‐Madaras, suggesting that there is a complete solid solution of roedderite and merrihueite in meteorites. We infer that the silica‐ and merrihueite/roedderite‐bearing chondrules and clasts experienced a complex formational history including: (a) fractional condensation in the solar nebula that produced Si‐rich and Al‐poor precursors, (b) melting of fractionated nebular solids resulting in the formation of silica‐pyroxene chondrules, (c) in some cases, fragmentation in the nebula or on a parent body, (d) reaction of silica with alkali‐rich gas that formed merrihueite/roedderite on a parent body, (e) formation of fayalitic olivine and ferrosilite‐rich pyroxene due to reaction of silica with oxidized Fe on a parent body, and (f) minor thermal metamorphism, possibly generated by impacts.
Meteorite falls in China and some related human casualty events
Authors: Yau Kevin , Weissman Paul , Yeomans Donald
Published: June 2012

Abstract— Statistics of witnessed and recovered meteorite falls found in Chinese historical texts for the period from 700 B.C. to A.D. 1920 are presented. Several notable features can be seen in the binned distribution as a function of time. An apparent decrease in the number of meteorite reports in the 18th century is observed. An excess of observed meteorite falls in the period from 1840 to 1880 seems to correspond to a similar excess in European data. A x2 probability test suggests that the association between the two data sets are real. Records of human casualties and structural damage resulting from meteorite falls are also given. A calculation based on the number of casualty events in the Chinese meteorite records suggests that the probability of a meteorite striking a human is far greater than previous estimates. However, it is difficult to verify the accuracy of the reported casualty events.
An update of a catalog of Chinese meteorites
Authors: Chen Yongheng , Wang Daode
Published: June 2012

Abstract— A catalog of Chinese meteorites is presented. The catalog updates Bian Depei's 1981 catalog and is complete through 1990 October. It includes data for 54 stone meteorites, 30 iron meteorites and a stony‐iron meteorite. Many of the meteorites were previously unknown in the West.
Lunar soil evolution processes and Apollo 16 core 60013/60014
Authors: Basu Abhijit , McKay David S.
Published: June 2012

Abstract— Soils of the 62‐cm deep Apollo 16 double drive tube 60013/14 are mature at the top and submature at the bottom. Modal analyses of 5529 grains from the 90–150 μm and the 500–1000 μm. fractions from 12 levels of the core show that, in general, agglutinate abundance increases somewhat monotonically to the top and mimics the Is/FeO profile. There is a general decrease in the modal abundance of monomineralic fragments towards the top, suggesting that agglutinates were formed in part at the expense of monomineralic grains, especially feldspars, which are by far the most abundant mineral in these soils. In detail, the top 27 cm of the core differs from the bottom 21 cm, and the middle 14 cm is intermediate in its properties. In the upper segment, variations in the abundances of feldspars correspond with those of feldspathic fragmental breccias and cataclastic anorthosites; in the bottom segment, a similar but weak correspondence between feldspars and crystalline matrix breccias is observed. Mixing of the comminuted products of these three rock types likely produced the bulk of the core material. Many single feldspars in all size fractions are remarkably fresh, show no damage from shock, and are similar in appearance to the large feldspars in anorthosites and feldspathic fragmental breccias, which we consider to be the primary sources of single feldspars in this core. Major (Na, Al, Si, K, Ca) and minor (Fe, Ba) element analyses of 198 single feldspar grains indicate the presence of only one population of feldspars, which is consistent with our interpretation of feldspar provenance. Classification of 890 monomineralic feldspar, olivine, pyroxene, and glass spherules on the basis of the presence or absence of thin brownish coating—related to reworking at the surface—shows that coated grains are much more abundant in the top segment than in the bottom segment.

A comparison with the mixing and maturation model (McKay et al., 1977) of soils in the core 60009/10, some 60 m away from 60013/14, shows that mixtures of an immature, nearly pure plagioclase soil (dominant in 60009/10) and another immature, crystalline breccia‐rich soil (dominant in 60013/14) may have matured through in situ reworking to produce the soils under investigation.

We conclude that the soils in this core are products of mixing along soil evolution Path 2 of McKay et al. (1974). Superimposed on that soil column is the reworking of the upper part, which has evolved more recently along Path 1. This core thus represents a consanguineous column of the lunar regolith with an upper reworked segment.
Interstellar graphite in meteorites: Isotopic compositions and structural properties of single graphite grains from Murchison
Authors: Zinner Ernst , Amari Sachiko , Wopenka Brigitte , Lewis Roy S.
Published: June 2012

Abstract— One hundred forty‐three carbon grains, ranging in size from 2 to 8 μm, from two chemical and physical separates from the Murchison CM2 chondrite, were analyzed by ion microprobe mass spectrometry for their C‐ and N‐isotopic compositions. Both separates are enriched in the exotic noble gas component Ne‐E(L). Ninety grains were also analyzed for their H and O contents and 118, for Si. Thirteen grains were analyzed by micro‐sampling laser Raman spectroscopy.

Round grains have large C‐isotopic anomalies with 12C/13C ratios ranging from 7 to 4500 (terrestrial ratio = 89). Nitrogen in these grains is also anomalous but shows much smaller deviations from the terrestrial composition, 14N/15N ratios ranging from 193 to 680 (terrestrial ratio = 272). Spherulitic aggregates and non‐round compact grains have normal C‐isotopic ratios but 15N excesses (up to 35%). Raman spectra of the analyzed grains indicate varying degrees of crystalline disorder of graphite with estimated in‐plane crystallite dimensions varying from 18 Å (highly disordered, similar to terrestrial kerogen) to ∼750 Å (well‐crystallized graphite). Element contents of H, O, and Si are correlated with one another, and H and O are probably present in the form of organic molecules. On the basis of morphology, the round grains fall into two groups: grains with smooth, shell‐like surfaces (“onions”) and grains that appear to be dense aggregates of small scales (“cauliflowers”). “Onions” tend to have lower trace element contents, isotopically light C (12C/13C > 89) and a high degree of crystalline order, whereas “cauliflowers” have a larger spread in trace element contents and C‐isotopic ratios (they range from isotopically light to heavy) but tend to have a low degree of crystalline order. However, these differences exist only on average, and no clear distinction can be made for individual grains.

A few limited conclusions can be drawn about the astrophysical origin of the carbon grains of this study. The 15N excesses in spherulitic aggregates and non‐round grains can be explained as the result of ion‐molecule reactions in molecular clouds. The round grains, on the other hand, must have formed in stellar atmospheres (circumstellar grains). Grains with isotopically light C must have formed in stellar environments characterized by He‐burning, either in the atmosphere of Wolf‐Rayet stars during the WC phase or in the He‐burning, 12C‐rich zone of a massive star, ejected by a supernova explosion. Isotopically heavy C is produced by H‐burning in the CNO cycle. Possible sources for grains with heavy C are carbon stars (AGB stars during the thermally pulsing phase) or novae, but the detailed distribution of 12C/13C ratios agree neither with the distribution observed in carbon stars nor with theoretical predictions for these two types of stellar sources.
Volatile trace elements in Antarctic ureilites
Authors: Wang Ming‐Sheng , Lipschutz Michael E.
Published: June 2012

Abstract— We report data for Ag, Au, Bi, Cd, Co, Cs, Ga, In, Rb, Sb, Se, Te, Tl, U and Zn in 15 different Antarctic ureilites. Contents of these mainly volatile trace elements in Antarctic ureilites are roughly comparable to those in the four known falls. Trends exhibited by these data apparently reflect geochemical fractionations in parental magma(s), which were closed to loss of vapor. Subsequent events (e.g., shock and crystallization) do not seem to have affected contents of these elements.
The Travis County, Texas, meteorites
Authors: McCoy Timothy J. , Ehlmann Arthur J. , Keil Klaus
Published: June 2012

Abstract— Studies of 52 specimens recovered from the find site of the original Travis County meteorite reveal the presence of two distinct meteorites. Travis County (a), which includes the original Travis County meteorite, is the more abundant meteorite and is classified as an H5(S4) shock‐blackened chondrite. Travis County (b) is classified as an H4(S2) chondrite with rare chondritic clasts of H group parentage, indicating that the meteorite is a breccia.