bluuebunny/crossref_metadata_2025 huggingface dataset:
COMPOSITIONAL STUDY OF THE LONE TREE, IOWA, CHONDRITE
Authors: McCormick G. R. , Carman J. H.
Published: June 2012

A meteorite, named for the location of its discovery near Lone Tree, Iowa, was found by Loren Westfall in May 1971. Electron microprobe and petrographic studies reveal its mineral composition to be olivine, low‐calcium clinopyroxene, high‐calcium clinopyroxene, troilite, kamacite, taenite and iron oxides.

On the basis of texture, olivine composition (19% Fa), low‐calcium clinopyroxene composition (17% Fs, 2% Wo) and metal (determined by modal analysis), this meteorite is classified as an H group bronzite chondrite. While it has characteristics of classes 3 and 4 (Van Schmus and Wood, 1967, Table 2) it fits class 4 better since low‐calcium pyroxene has a MD of 5.6%, olivine has a MD of 3.2%, turbid glass is present in chondrules, feldspar is absent, and the matrix is opaque. The opacity of the matrix may be due to iron oxides in microfractures in a microcrystalline matrix.
THE MOAMA EUCRITE — A PYROXENE‐PLAGIOCLASE ADCUMULATE
Authors: Lovering J. F.
Published: June 2012

A non‐brecciated, relatively coarsely crystalline eucrite was found in 1940 near Moama, southern New South Wales, Australia. The texture and mineralogy (plagioclase 49.1 volume %, pyroxene 48.9%, tridymite 0.72%, chromite 1.0%, troilite 0.24% and metallic iron 0.14%) are characteristic of an adcumulate formed in a terrestrial layered igneous intrusion. Its composition and texture most closely resemble the eucrite Serra de Magé. Moama and Serra de Magé are the best approximations to the pyroxeneplagioclase cumulates which McCarthy et al. (1973) propose have separated from a primary magma to produce the eucrite group of achondrites. Primary (coarse) and secondary (fine) augitic exsolution lamellae in the host hypersthene grains indicate a cooling history for the Moama eucrite similar to that of mafic rocks in slowly cooled, large, layered terrestrial intrusions such as Bushveld.
LA METEORITE DE TILLABERI
Authors: MICHEL‐LEVY CHRISTOPHE , MALEZIEUX Jean‐Marie
Published: June 2012

The Tillaberi stone fell in April 1970 in Republic of Niger. In the 157 g piece sent to Paris, a centimeter wide lithic inclusion is found. Contrary to previous assumptions, the stone is an L6 chondrite in which few chondrules can be distinguished; olivine is Fa 25 ± 0.4 percent with minor amounts of Ca, Cr, Ti; orthopyroxene is Fs 21.6 ± 1.2 percent with a rather large scatter of the amounts of minor elements. The feldspar, well developed, contains 10 to 11 percent An, 84 to 85 percent Ab, five percent Or, and 0.77 ± 0.09 percent FeO. The lithic inclusion contains much feldspar which corresponds to 14 to 17 percent An, 75 to 79 percent Ab, four to five percent Or without almost any FeO. This inclusion contains also rounded grains of olivine and minute crystals of chromite. It has a frothy microdoleritic texture with a frozen border against the chondritic material. As the nickel rich grains are either martensite or acicular plessite and the silicates are undeformed, a quick cooling after a short but intense heating is postulated to account for the mineralogical characteristics.
ARTIFICIALLY‐INDUCED THERMOLUMINESCENCE GRADIENTS IN STONY METEORITES
Authors: Vaz J. E. , Sears D. W.
Published: June 2012

Several meteorites show variations in natural thermoluminescence intensity with depth. To investigate this, the gamma‐ray induced thermoluminescence of the Plainview, Ucera, and Lost City meteorites has been analyzed. The results show that the thermoluminescence gradients in the meteorites are related to the concentration of electron traps, probably as a result of some of them being produced by cosmic ray bombardment.
HAPPY CANYON: A NEW TYPE OF ENSTATITE ACHONDRITE
Authors: Olsen Edward J. , Bunch T.E. , Jarosewich Eugene , Noonan Albert F. , Huss Glenn I
Published: June 2012

Happy Canyon [found: 1971, 34° 46.5′N, 101° 33.6′W, Texas] consists of about 85 vol. % enstatite (Fs 0.4%), 5 to 10 vol % plagioclase (An 26%), and 5 vol % diopside (Fs 0.9%). In addition, there are minor remnants of metal (Ni 6.35 wt %, Si‐free) and troilite (with 5.10 wt % Cr and 1.15 wt % Ti) that have survived extensive terrestrial weathering. The meteorite has a cumulate texture, uniform‐size euhedral, prismatic crystals of enstatite (0.3 to 0.4 mm long) with interstitial plagioclase, diopside, troilite, and metal. The enstatite crystals are dominantly disordered and occur in alignments that suggest flow. There are no chondrules or remnants of chondrules. The enstatite crystals contain internal negative crystal voids, which are charactieristic of enstatite achondrites, as well as internal branching submicron rivulet dislocations. The bulk composition is that of an E6 enstatite chondrite, however, it has the texture of a crystal cumulate; achondritic, but unlike that of enstatite achondrites. Glass of a granitic composition occurs mainly in the mesostasis and is compositionally like the glass found inside pyroxene crystals in the Cumberland Falls enstatite achondrite.

Happy Canyon is most simply explained as an E6 composition that has melted and reprecipitated at a slightly higher oxidation state, at some depth (> 7 km), possibly in the core volume of a small, asteroidal‐size parent body. In terms of classification, it occupies the gap between the recrystallized enstatite chondrites and the igneous, crystalline, unbrecciated enstatite achondrites like Shallowater. Happy Canyon is a new type of enstatite achondrite
HABIT PLANES OF PLATELIKE SCHREIBERSITE IN HEXAHEDRITES*
Authors: Randich Erik , Eckelmeyer K.H.
Published: June 2012

We have measured the habit planes of plate rhabdites [(Fe, Ni)3P] with respect to the parent kamacite phase (α, Fe‐Ni) in eight hexahedrites. This was accomplished using x‐ray diffraction plus two‐surface trace analysis. Results show that plate rhabdites form on either {001} or {122} planes in the parent kamacite. The meteorite Uwet exhibits a {112} habit plane which is possibly an anomaly due to the occurrence of a large shock event during rhabdite nucleation (∼ 550–650 °C).
AN ANALYTICAL SCHEME FOR CHONDRITIC METEORITES
Authors: Hughes T.C. , Hannaker P.
Published: June 2012

A chemical scheme is reported for the analysis of chondritic materials and results are presented for the Cocklebiddy meteorite. Analytical problems associated with chondrite inhomogeneity including phase leaching selectivity and the completeness of individual phase attack are considered. Data obtained by this method can be used to classify chondrites according to the accepted weight and molar ratio methods (Van Schmus and Wood, 1967: Wasson, 1974)

The analytical scheme uses selective leaching techniques to determine, in each sample, the chemical composition of metallic, sulphide and silicate phases. Elemental concentrations are obtained by atomic absorption spectrometry, flame photometry, spectrophotometry or titration techniques, and the total sample average compositions are determined on fully oxidised specimens by XRF
STUDIES OF BRAZILIAN METEORITES XIII. MINERALOGY, PETROLOGY, AND CHEMISTRY OF THE PUTINGA, RIO GRANDE DO SUL, CHONDRITE
Authors: Keil K. , Lange D. , Ulbrich M.N.C. , Gomes C.B. , Jarosewich E. , Roisenberg A. , Souza M.J.
Published: June 2012

The Putinga, Rio Grande do Sul, chondrite (fall, August 16, 1937), consists of major olivine (Fa24.8), orthopyroxene (Fs21.3), and metallic nickel‐iron (kamacite, taenite, and plessite); minor maskelynite (Ab81.0An12.4Or6.6) and troilite; and accessory chromite (Cm79.0Uv8.2Pc1.8Sp11.0) and whitlockite. Mineral compositions, particularly of olivine and orthorhombic pyroxene, as well as the bulk chemical composition, particularly the ratios of Fe°/Ni° (5.24), Fetotal/SiO2 (0.58), and Fe°/Fetotal (0.27), and the contents of Fetotal (22.42%) and total metallic nickel‐iron (7.25%) classify the meteorite as an L‐group chondrite. The highly recrystallized texture of the stone, with well‐indurated, poorly discernible chondrules; xenomorphic, well‐crystallized groundmass olivine and pyroxene; and the occurrence of poikilitic intergrowth of olivine in orthopyroxene suggest that Putinga belongs to petrologic type 6. Maskelynite of oligoclase composition was formed by solid state shock transformation of previously existing well‐crystallized plagioclase at estimated shock pressures of about 250–350 kbar. Thus, recrystallization (i.e., formation of well‐crystallized oligoclase) must have preceded shock transformation into maskelynite.
STUDIES OF BRAZILIAN METEORITES XIV. MINERALOGY, PETROLOGY, AND CHEMISTRY OF THE CONQUISTA, MINAS GERAIS, CHONDRITE
Authors: Keil K. , Kirchner E. , Gomes C.B. , Jarosewich E. , Murta R.L.L.
Published: June 2012

The Conquista chondrite consists of major olivine, low‐Ca pyroxene (both ortho‐ and twinned clino‐), troilite and metallic nickel‐iron; minor glassy to microcrystalline material and pigeonite; and accessory chromite, high‐Ca clinopyroxene and hydrous ferric oxides that formed by terrestrial weathering of metallic nickel‐iron. Results of microscopic, electron microprobe, and bulk chemical studies, particularly the compositions of olivine (Fa17.2) and low‐Ca pyroxene (Fs15.4); the contents of metallic nickel‐iron (18.5%) and total iron (25.83%); and the ratios of Fe°/Fetotal (0.64), Fe°/Ni° (9.59) and Fetotal/SiO2 (0.69) indicate H‐group classification. 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 of twinned low‐Ca clinopyroxene suggest that Conquista is of petrologic type 4.
METAL AND SCHREIBERSITE IN MAYO BELWA, AN ENSTATITE ACHONDRITE
Authors: Graham A.L.
Published: June 2012

The Mayo Belwa meteorite (an aubrite) contains discrete metal grains ranging in size from less than 1 μm to 300 μm across, and schreibersites up to 25 μm across. Intergrowths of metal and schreibersite also occur. These phases are distributed heterogeneously throughout the meteorite and are present both in the fine‐grained matrix and within silicate crystals. The concentrations of the elements Ni, Fe, Si, Co, P, were determined in grains larger than 4 μm across. Most metal grains have 1–8% Ni, the total range being 0.8–23.5% Ni. The 1–8% Ni metal may be sub‐divided into two compositional groups, one relatively compact, having 1–3.8% Ni, 0.1‐0.3% Si; the second having a much greater range in both Ni and Si (∼ 4–12%, 0.1‐1.2% respectively). There is no zonation in the Si contents of individual grains. Neither the size of the grains nor their environment correlates with their Ni or Si contents, though there is a tendency for low Ni, low Si metal to be within enstatite crystals. Schreibersite (8–14.4% Ni) occurs as isolated grains or associated with low‐Ni metal; it generally contains less than 500 ppm Si. The wide range in the Ni contents of the metal distinguishes it from the metal of the E‐chondrites, and argues against an E‐chondrite source for this metal.
THE METEORITE CRATERS OF MORASKO IN POLAND
Authors: Classen J.
Published: June 2012

In 1914, in Morasko near Poznań, a 77.5 kg iron meteorite was found. Later there were additional findings. In 1955 seven crater‐like structures, situated in the neighborhood of the meteorite finds, were identified. Until now it has been doubtful whether the iron meteorites and the craters belong together. New examinations by the author confirm beyond any doubt that the meteorites and the craters were caused by the same event.
THE GALATIA, KANSAS, CHONDRITE
Authors: Van Schmus W.R. , Kei Klaus , Lange D.E. , Conrad G.H.
Published: June 2012

The Galatia meteorite was found in August, 1971, approximately 7 km ENE of Galatia, Barton County, Kansas (98° 53′W., 38° 39.5′N). The single stone weighed 23.9 kg and is partially weathered. Olivine (Fa24.9) and pyroxene (Fs20.9) compositions indicate L‐group classification, and textural observations indicate that the stone is of petrologic type 6. Galatia is similar in many respects to the Otis L6 chondrite (found 20 km to the west), but it does not have the brecciated structure of Otis and, thus, it is not part of the same fall.
CLAST‐LADEN MELT‐ROCK FRAGMENT IN THE ADAMS COUNTY, COLORADO, H5 CHONDRITE
Authors: Fodor R.V. , Keil Klaus , Prinz Martin , Ma M.‐S. , Murali A.V. , Schmitt R.A.
Published: June 2012

The Adams County, Colorado, H5 chondrite contains a lithic fragment, 1 cm in size, that is texturally and mineralogically quite different from the chondritic host. It is composed of: a groundmass of fine‐grained euhedral to subhedral olivine (3–15 μm) and interstitial glass enclosing larger olivine and pyroxene grains (0.15‐0.5 mm; about 15 vol %); an assemblage of enstatite grains (subfragment within) and an assemblage of olivine plus orthopyroxene (a second subfragment); and about 11 vol % grains of mixed troilite and nickel‐iron metal. Analyses yielded these results: (i) olivine grains of the fragment groundmass have a compositional range (Fa12–45) and most grains contain substantial CaO and Cr2O3 (∼ 0.20 and 0.30 avg. wt%, respectively); interstitial glass has ∼ 55 wt% SiO2; (ii) larger olivine grains of the fragment are similarly high in CaO and Cr2O3 and also have a wide FeO/MgO range; one unusual pyroxene is an Mg‐rich pigeonite; (iii) the metal is martensite in composition (11–14 wt% Ni); and (iv) major and trace element analyses by INAA indicate an H‐group bulk composition for the entire 1 cm lithic fragment.

On the basis of its texture and bulk and mineral compositions, the fragment is interpreted to represent unequilibrated H‐group material that was partly melted by impact. The Ca‐ and Cr‐enriched groundmass olivine and interstitial glass resulted from rapid crystallization of the chondritic melt. The Ca‐ and Cr‐enriched larger silicate grains, including the enstatite sub‐fragment and the pigeonite grain, are residual, unmelted clasts from the target material (this is supported by the presence of similar material in actual H3 chondrites). Further impact brecciation of the clast‐laden melt material, and resultant impact‐splashing accounts for the presence of the fragment in the H‐group Adams County host and documents the coexistence of unequilibrated and equilibrated H‐group material as surface regolith on one parent body.
NEPHELINE AND SODALITE IN A BARRED OLIVINE CHONDRULE FROM THE ALLENDE METEORITE
Authors: Lumpkin Gregory R.
Published: June 2012

Nepheline and sodalite have been found in association with glass in a barred olivine chondrule from the Allende C3V meteorite. The major minerals of the chondrule are olivine (Fo80–88), bronzite (En85Fs12Wo3), and chromite. Olivine bars are separated by glass of nearly pure plagioclase composition (An81–99). Olivine composition is more Fe‐rich than predicted by olivine‐liquid equilibria (Fo96). Conditions of non‐equilibrium are implied from this and the presence of plagioclase glass and small amounts of subcalcic diopside (En75Fs12Wo13) in the chondrule. The properties of this chondrule are consistent with liquid condensation, but melting of an amoeboid olivine aggregate or similar object could also have generated the chondrule‐forming liquid. Nepheline and sodalite appear to have crystallized from this liquid under non‐equilibrium conditions.
THE LAHRAULI UREILITE
Authors: Bhandari N. , Shah V.G. , Graham A.
Published: June 2012

A meteorite which fell at Lahrauli, district Basti, U.P. (India) in 1955 has been examined for mineralogical, chemical and cosmogenic characteristics. It contains pigeonite Wo7.7Fs18 (with Cr2O3 = 1.2% and Al2O3 = 0.4%), olivine Fo79 (with CaO = 0.3% and Cr2O3 = 0.7%) and diamond. The basic similarities of this meteorite to Goalpara, Dyalpur, Havero and Novo Urei indicate that it is a ureilite. Cosmic ray tracks have been measured in the olivine and pyroxene grains. Track density of 2.3 × 106 per cm2 in olivines and VVH/VH ratio of 10−3 is similar to that observed in other meteorites.
COMPOSITION AND ORIGIN OF THE UNUSUAL OKTIBBEHA COUNTY IRON METEORITE
Authors: Kracher Alfred , Willis John
Published: June 2012

We have analyzed Oktibbeha County, the most Ni‐rich iron meteorite, for Ni, Co, Cu, Ga, Ge, As, Sb, Ir, and Au. Cu and Sb are higher than in any other iron, but other trace elements are within the ranges typically found in iron meteorites. Extrapolation of trace element trends in group IAB indicates that Oktibbeha County is a member of this group. This sheds light on the origin of groups IAB and IIICD, which are thought to be derived from impact melts on parent bodies of chondritic composition.

Lafayette (iron), another sample reported in the literature to have a similarly high Ni content, is probably a pseudometeorite.
COMPLEX SHOCK‐INDUCED Fe‐Ni‐S‐Cr‐C MELTS IN THE HAIG (IIIA) IRON METEORITE
Authors: Bevan A.W.R. , Kinder J. , Axon H.J.
Published: June 2012

The Haig (IIIA) iron meteorite material (BM 1968,280) in the Collection of the British Museum (Natural History) displays pre‐terrestrial shear deformation which transects a small troilite‐daubréelite‐cohenite nodule. Five globular areas (< 1 mm) with dendritic structures indicating rapid solidification from melts occur within and around the larger part of the transected nodule. All shock deformation structures and shock‐heating effects exhibited by Haig. are of pre‐terrestrial origin and at least four successive alterations to the original structure are evident.

Partial bulk analyses of the melt globules indicate complex mixtures of approximately 55 wt % troilite, 24 wt % metal, 14 wt % daubréelite and 7 wt % cohenite. It is suggested that a compressive environment maintained the melts as discrete pools of liquid.

The diameters of the globules (< 0.5 mm) and spacing of the dendrite arms (< 1 μm) indicate solidification at > 106 °C sec−1 which is the fastest cooling rate yet recorded in meteorites.
THE CRACKING HISTORY OF SERRANIA DE VARAS: AN ALTERNATIVE VIEW
Authors: Axon H.J. , Smith E. , Knowles F.
Published: June 2012

Buchwald's (1975) theory of thermally induced cracking in Serrania de Varas is critically examined from the standpoint of elementary stress analysis. New metallographic observations are presented. It is suggested that thermal cracking is unlikely to have been operating in this material.
CALCIUM‐ALUMINIUM‐RICH CHONDRULES IN THE UNEQUILIBRATED ORDINARY CHONDRITES
Authors: Nagahara Hiroko , Kushiro Ikuo
Published: June 2012

Calcium‐aluminium‐rich chondrules were found in L‐3 (ALH‐77015) and LL‐3 (ALH‐77278) chondrites. They consist of spinel, olivine, fassaite and glassy groundmass enriched in anorthite component. The bulk chemical compositions of the two chondrules are nearly the same and resemble those of the calcium‐aluminium‐rich inclusions in the carbonaceous chondrites, but the former is more enriched in MgO and SiO2 and depleted in Al2O3 and CaO. The calcium‐aluminium‐rich chondrules would have been primarily early condensates which existed at the place where the chondrules were formed, and heated up to 1400 °C or higher to have melted and cooled at the rate similar to those for other chondrules, or the products of intensive heating followed by reaction with gas.
GLANGGANG AND SELAKOPI: TWO NEW PAIRED (?) INDONESIAN CHONDRITES
Authors: Fredriksson K. , Peretsman G.S.
Published: June 2012

The Indonesian meteorites, Selakopi, an H‐5 chondrite, and Glanggang, a breccia with H‐6 fragments is an H‐5 chondritic matrix, were recovered on the same day from sites only 50 km apart. The textures and compositions of Selakopi and the H‐5 portion of Glanggang are very similar, indicating that they are closely related. The bulk chemistry of the H‐6 portion of Glanggang is also very similar to that of the samples mentioned. It has therefore been concluded that Selakopi and the Glanggang breccia fragments were derived from the same source area and were probably ejected at the same time. Minor differences in bulk composition and texture among the three samples may be attributed to local variations on the parent body. However, for reasons stipulated in the conclusion, we recommend that separate names be maintained for these meteorites until further, more definitive investigations have been made.
GEOLOGY AND TERRESTRIAL AGE OF THE DERRICK PEAK METEORITE OCCURRENCE, ANTARCTICA
Authors: Kamp Peter J.J. , Lowe David J.
Published: June 2012

Sixteen iron meteorites together weighing 320 kg were recovered from the north‐eastern flank of Derrick Peak, northern Britannia Range, Antarctica (156°30′E, 80°05′S), in December 1978. The well preserved meteorites rested cleanly upon an elevated, lag covered, glacially carved post‐Middle Miocene to Pliocene bench cut into Devonian orthoquartzites intruded by Jurassic dolerite, and at a lower elevation upon Middle Pleistocene glacial drifts. In considering that the irons are in situ, and based on drift correlations along the Transantarctic Mountains, a maximum terrestrial age of 200,000–300,000 years B.P. is favoured.
PETROLOGY OF EETA79006 AND IMPLICATIONS FOR THE FORMATION OF POLYMICT EUCRITES
Authors: Simon Steven B. , Papike J.J. , Fuhrman M.
Published: June 2012

A newly found polymict eucrite, EETA79006, is described. Lithic clasts are similar to those found in howardites and fall into four groups: fine‐grained (aphanitic), coarse‐grained, basaltic, and cataclastic. All have eucritic compositions and differ mainly in cooling and deformation histories. Some basaltic clasts cooled faster than others and may be impact melts. Analysis of pyroxene and feldspar in the matrix and in 20 lithic clasts indicates that the matrix was not derived from the observed lithic clast population. This meteorite and similar polymict eucrites may have formed by addition of younger more fractionated lithic clasts to the regolith of the parent body.
CLASSIFICATION OF THE ALLAN HILLS A77307 METEORITE
Authors: Sears D.W.G. , Ross M.
Published: June 2012

The Allan Hills A77307 meteorite has variously been described as a CO, CV, and a unique CO‐CM related chondrite. We have found that its thermolum‐inescence properties are very different from the established members of the CO chondrite class; it has a TL peak at 170 and a suggestion of a peak at 250°C, while CO chondrites have peaks at 91 ± 7 and 203 ± 11°C. Either the meteorite has suffered some form of alteration or it is not a normal CO chondrite. The latter is consistent with petrologic and compositional data which we interpret to indicate that although Allan Hills A77307 is related to CO chondrites it is not a normal member of that group.
FURTHER FINDS FROM THE MUNDRABILLA METEORITE SHOWER
Authors: De Laeter J.R. , Cleverly W.H.
Published: June 2012

Two new large iron meteorites, weighing 840 kg and 800 kg respectively, have been recovered from the Nullarbor Plain in the vicinity of the original Mundrabilla meteorite site, and are now at the Western Australian Museum in Perth. Numerous small knucklebone‐shaped irons were also found at Tookana Rock Hole in the vicinity of Eucla. X‐ray fluorescence spectrometry of these meteorites confirms that the additional finds are members of the Mundrabilla meteorite shower.
THE NOMENCLATURE OF POLYMICT BASALTIC ACHONDRITES
Authors: Delaney Jeremy S. , Takeda H. , Prinz M. , Nehru C.E. , Harlow G.E.
Published: June 2012

The subgroups within the basaltic achondrite suite are defined using the structural criterion of Wahl (1952). The ‘monomict’ meteorites are samples of a single lithology while the polymict meteorites are those containing two or more lithologies. The ‘monomict’ subgroups eucrites, cumulate eucrites and diogenites are subdivided into both brecciated and unbrecciated meteorites. The polymict achondrites sample a petrological‐compositional continuum that contains both mafic and ultramafic rock types and may be subdivided into several groups. Two groups of polymict basaltic achondrites, the polymict eucrites and howardites are separated using an arbitrarily defined criterion. The recommended criterion is based on the amount of magnesian ortho‐pyroxenite (diogenite) component in the meteorite. Howardites contain more than 10% and polymict eucrites contain less than 10%.

The criteria proposed (perhaps with minor variations), appear to reconcile the ambiguities caused by the polymict eucrites. These meteorites, using earlier structural criteria, are howardites, but using mineralogical‐chemical criteria are eucrites. As a subgroup of the polymict achondrites, their relationship with the howardites is clear, and the preservation of the term ‘eucrite’ in their name highlights their modal affinity to the monomict eucrites.
FRAGMENTAL BRECCIAS AND THE COLLISIONAL EVOLUTION OF ORDINARY CHONDRITE PARENT BODIES
Authors: Rubin Alan E. , Rehfeldt Angeline , Peterson Eric , Keil Klaus , Jarosewich Eugene
Published: June 2012

Our survey of type 4–6 ordinary chondrites indicates that gas‐poor, melt‐rock and/or exotic clast‐bearing fragmental breccias constitute 5%, 22% and 23%, respectively, of H, L and LL chondrites. These abundances contrast with the percentages of solar‐gas‐rich regolith breccias among ordinary chondrites: H (14%), L (3%) and LL (8%) (Crabb and Schultz, 1981). Petrologic study of several melt‐rock‐clast‐bearing fragmental breccias indicates that some acquired their clasts prior to breccia metamorphism and others acquired them after metamorphism of host material. In general, the melt‐rock clasts in gas‐poor H chondrite fragmental breccias were acquired after breccia metamorphism and were probably formed by impacts into boulders or exposed outcrops of H4‐6 material in the H chondrite parent body regolith. In contrast, most of the melt‐rock clasts in gas‐poor L and LL fragmental breccias were acquired prior to breccia metamorphism. The low abundance of regolith breccias among L chondrites and evidence that at least two‐thirds of the L chondrites suffered a major shock event 0.5 Gyr ago, suggest that the L parent body may have been disrupted by a major collision at that time and that the remaining parent body fragments were too small to develop substantial regoliths (e.g., Heymann, 1967; Crabb and Schultz, 1981). Such a disruption would have exposed a large amount of L chondrite bedrock, some of which would consist of fragmental breccias that acquired melt‐rock clasts very early in solar system history, prior to metamorphism. The exposed bedrock would serve as a potential target for sporadic meteoroid impacts to produce a few fragmental breccias with unmetamorphosed melt‐rock clasts. The high proportion of genomict brecciated LL chondrites reflects a complex collisional history, probably including several episodes of parent body disruption and gravitational reassembly. Differences in the abundances of different kinds of breccias among the ordinary chondrite groups are probably due to the stochastic nature of major asteroidal collisions.
LITHOPHILE ELEMENTS IN INDIVIDUAL CHONDRULES OF THE H‐4 MAFRA CHONDRITE
Authors: Sighinolfi G. Paolo , Gorgoni Carlo
Published: June 2012

Bulk and trace lithophilic elements (Al, Ca, Fe, Mn, Ti, Cr, Sr, V and Zn) have been determined in individual chondrules and in other constituents of the H‐4 Mafra chondrite by means of flameless A.A. microanalysis. Twenty‐four large sized (> 1 mg) chondrules, composite samples of minor‐sized (0.1 and 0.2 mg) chondrules and fine‐grained “interchondrular” material have been examined. Data on the large‐sized chondrules exhibit large compositional variations among cosmochemically coherent groups of elements. A weak anti‐correlation was found between the geochemically coherent refractory V and volatile Zn. A possible mass‐composition relationship is suggested by the apparent concentration of lithophile high‐temperature condensing elements (Ca, Al, Ti) in the minor‐sized chondrules. Compositional features tend to support the hypothesis that chondrules originate from a large number of precursor components constituting a distinct grain population in the solar nebula. Melting through a sudden heating of random mixtures of these precursor grains was possibly followed by further condensation of volatiles and accretion.
SOLAR ABUNDANCES OF THE ELEMENTS
Authors: Manuel O.K. , Hwaung Golden
Published: June 2012

The isotopic compositions of noble gases in the solar wind show high enrichments of light isotopes. When corrected for mass fractionation all five noble gases there can be resolved in terms of the two primitive noble gas components that have been identified in planetary solids. Reasons are presented for assigning the fractionation to a solar process that selectively enriches lighter nuclei at the surface of the Sun. When abundances of the elements at the Sun's surface are corrected for this fractionation, it is shown that atomic abundances for major elements in the bulk Sun are (in decreasing order): Fe, Ni, O, Si, S and Mg. Solar elements at about the 1% atomic abundance level include He, C, Ne, Ca and Cr. These results suggest that fusion of hydrogen is probably not the Sun's primary energy source.
ACHONDRITE ALHA77005: ALTERATION OF CHROMITE AND OLIVINE
Authors: Smith Joseph V. , Steele Ian M.
Published: June 2012

The olivine crystals of the 77005 achondrite are brown except for colorless shock lamellae, mottled patches, and grains adjacent to pools of impact melt. Sporadic dark alteration patches in brown olivine and Cr‐rich spinel gave the following average electron‐microprobe analyses: (olivine) P2O5 0.9, SiO2 57.9, TiO2 0, Al2O3 0.7, Cr2O3 0.4, V2O3 0, Fe2O3 (assumed oxidation state) 17.0, MgO 1.6, CaO 0.2, Na2O 0, K2O 1.8, SO3 (assumed oxidation state) 9.2, Cl 0.1, sum 89.8 wt. %; (spinel) P2O53.5, SiO22.1, TiO2.2.2, Al2O32.1, Cr2O3 13.4, V2O3 0.8, Fe2O3 40.7, MgO 0.9, CaO 0.1, Na2O 0, K2O 2.0, SO3 11.1, Cl 0.1, sum 79.0 wt.%. Ion‐microprobe analyses revealed H in both. Rare orange patches in brown olivine from another area gave SiO2 33–35, FeO 30‐28, MgO 28–32, sum 93 wt. %. Thermal metamorphism under dry oxidizing conditions is discussed as a possible alternative to shock‐induced oxidation for generation of the brown olivine (McSween and Stöffler). Because alteration patches transgress shock lamellae, and because sulfatic alteration occurs in fusion crusts of Antarctic meteorites (Gibson et al., 1983), alteration of the 77005 achondrite at the Antarctic surface is preferred to a complex series of processes needed for pre‐terrestrial alteration.
THE BROWNELL AND NESS COUNTY (1894) L6 CHONDRITES: FURTHER SORTING‐OUT OF NESS COUNTY METEORITES
Authors: Rubin Alan E. , Read William F.
Published: June 2012

Brownell is a new, moderately shocked, L6 chondrite from Ness County, Kansas that is petrologically distinct from the other L6 chondrites from Ness County. These latter meteorites, Wellmanville, Franklinville and Ness County (1894), are very similar in their olivine and low‐Ca pyroxene compositional distributions, kamacite Co contents, modal abundances of metallic Fe, Ni and presence of martensitic metallic Fe, Ni (∼ 14 wt. % Ni). However, their silicates indicate that they have been shocked to different extents. We suggest that all three probably represent a single, heterogeneously‐shocked, L6 fragmental breccia that fell over a large area, > 30 km in length.
CONSTRAINTS ON CHONDRULE ORIGIN FROM PETROLOGY OF ISOTOPICALLY CHARACTERIZED CHONDRULES IN THE ALLENDE METEORITE
Authors: McSween Harry Y.
Published: June 2012

Petrographic and chemical features of Allende ferromagnesian chondrules previously analyzed for oxygen and silicon isotopes by Clayton et al. (1983a) provide additional information on chondrule origin. Allende, like other carbonaceous chondrites, contains two chondrule populations, but one of these is represented by only one chondrule in this isotopically characterized set. All Allende chondrules fall along an isotopic mixing line, probably defined by an 16O‐rich solid component and an isotopically heavier oxygen gaseous exchange component. Differences in the amounts of isotopic exchange for porphyritic and barred chondrules presumably resulted from varying degrees of melting. Those porphyritic chondrules containing abundant relict grains experienced the least isotopic exchange. Chondrules with high bulk FeO/(FeO + MgO) ratios apparently persisted longer as liquids and contain more of the exchange component. The distinct directions of oxygen isotopic exchange in chondrules from carbonaceous, ordinary, and enstatite chondrites indicate that each formed from different solid precursor materials. Silicon isotopic variations in Allende chondrules probably reflect evaporative loss of lighter isotopes; however, silicon loss is also controlled by chondrule sizes, which are unknown. Observed correlations point to the importance of kinetic factors in a gaseous nebula for chondrule genesis, and are not consistent with models that explain chondrules as mixtures of several solids with distinct oxygen and silicon isotopic compositions.
EVIDENCE OF HIGH COSMIC DUST CONCENTRATIONS IN LATE PLEISTOCENE POLAR ICE (20,000–14,000 YEARS BP)
Authors: LaViolette Paul A.
Published: June 2012

Dust filtered from the lower portion of the Camp Century ice core (77°10'N, 61°08'W) has been analyzed for the presence of the cosmic dust indicators iridium and nickel using the neutron activation analysis technique. This study was carried out to test the hypothesis that the climatic change toward the end of the Last Ice Age was triggered by an incursion of nebular material into the Solar System. The analytical results are consistent with this hypothesis. Concentrations of Ir and Ni in the ice were one to two orders of magnitude higher during the latter portion of the Last Ice Age (19,700‐14,200 years BP) as compared with current levels. Ir and Ni levels in 6 out of 8 samples suggest a total cosmic dust influx rate of about 0.5−3 times 107 tons/yr to the Earth's surface as compared with about 1−7 x× 105 tons/yr for the current influx. Elemental concentrations in 6 of the 8 dust samples ranged from 6− 96 ppb for Ir and < 60 to 3200 ppm for Ni. It is concluded that a major fraction of this invading dust would have been of submicron size in which case the concentration of light scattering particles would have been sufficient to significantly alter the light transmission properties of the Solar System and substantially affect the Earth's climate. These results mark the first time that cosmic dust deposition rates have been estimated for prehistoric times using the polar ice record.
ASTEROIDAL SOURCE OF ORDINARY CHONDRITES*
Authors: Wetherill George W.
Published: June 2012

The orbital evolution of asteroidal fragments with diameters ranging from 10 cm to 20 km, injected into the 3:1 Kirkwood gap at 2.50 A.U., has been investigated using Monte Carlo techniques. It is assumed that this material can become Earth‐crossing on a time scale of 106 years, as a result of a chaotic zone discovered by Wisdom, associated with the 3:1 resonance. This phenomenon, as well as close encounter planetary perturbations, the v6 secular resonance, and the ablative effects of the Earth's atmosphere are included in the determination of the orbital characteristics of meteorites impacting the Earth derived by fragmentation of this asteroidal material. It is found that the predicted meteorite orbits closely match those found for observed ordinary chondrites, and the total flux is in approximate agreement with the observed fall rate of ordinary chondrites. About 10% of the predicted impacting bodies are meteorite‐size bodies originating directly from the asteroid belt. The remainder are obtained by subsequent fragmentation of larger (∼1 m to 20 km diameter) Earth‐crossing asteroidal fragments. The largest of these fragments are observable as Apollo‐Amor objects. Thus the apparent paradox between the orbital characteristics of observed ordinary chondrites and those predicted from Apollo object sources is reconciled. Both appear to be complementary aspects of the same phenomena. No other asteroidal resonance is found to be satisfactory as a source of ordinary chondrites. These meteorites are therefore most likely to be derived from S asteroids in this limited region of the asteroidal belt, the largest of which are 11 Parthenope, 17 Thetis, and 29 Amphitrite.
URANIUM DISTRIBUTION and “EXCESSIVE” U‐He AGES IN IRON METEORITIC TROILITE
Authors: Fisher David E.
Published: June 2012

Uranium was measured by fission track analysis in meteoritic troilite and graphite. The distribution is extremely heterogeneous, with a few high‐U grains dominating the total abundances. U/He ages cannot be estimated from such a distribution pattern, and therefore previously reported excessive ages are not valid.
E‐CHONDRITES: SIGNIFICANCE OF THE PARTITION OF ELEMENTS BETWEEN ‘SILICATE’ AND ‘SULPHIDE’
Authors: Easton A.J.
Published: June 2012

Bulk chemical analyses of six E‐chondrites (Daniel's kuil, Khairpur, Kota Kota, Saint‐Sauveur, South Oman and St Mark's) are given, together with partial analyses of a further five (Blithfield, Hvittis, Indarch, Jajh deh Kot Lalu and Pillistfer). The distribution of some normally lithophile elements (Al, Ca, Cr, K, Mg, Na, P and Ti) between silicate and sulphide groups of minerals was determined using the selective attack by dry chlorine (350°C) on magnetically separated fractions. Subdivision of the E‐chondrites into types I and II (Yavnel;, 1963; Anders, 1964) is accepted and it is shown using chemical data that St Mark's and Saint‐Sauveur should be included in type I.

Sulphides contribute an unexpectedly high proportion of several elements to the bulk: e.g. Ca (av. 88.5% type I, 66.3% type II); Ti(av. 77.1% type I, 84.8% type II) and P as phosphide (av. 44.4% type I, > 83.2% type II). The proportion of Ti contributed to the bulk composition by the sulphides in types I and II increases with increae in ‘thermal metamorphic effect’ (Easton, 1983b) within each type.

There is marked variability in the relative abundances of metal, phosphide, silicate and sulphide among the members of each type in keeping with their aggregate nature.

The chemical composition of the ‘silicate’ and ‘sulphide’ in type IE‐chondrites differs from that in type II (e.g. CaO in the silicates, Mg in the bulk sulphides) which therefore precludes the isochemical evolution of all E‐chondrites from a common parent material. Partition of Ti between silicate and sulphide groups of minerals indicates that types I and II E‐chondrites originated in separate, chemically distinct bodies.
LUKANGA SWAM: PROBABLY ASTROBLEME
Authors: Vrána Stanislav
Published: June 2012

This article summarizes information relevant to the interpretation of Lukanga Swamp — a depression some 52 km in diameter in central Zambia — as a considerably eroded astrobleme. The results of reconnaissance geological mapping, an airborne magnetic survey and petrological study of a small set of samples of impact rocks are presented. Circular topographic features coincide with a remarkably subdued magnetic field. A circular set of tangential faults indicates a diameter of the outer rim approximately 110 km. Polymict breccia occur, carrying marble megaclasts (klippes) up to 50 m long. Strongly shocked quartz clasts with several sets of decorated planar features are present as well as devitrified, flow‐banded silica glass exhibiting decarbonation textures around marble clasts. Provisional correlation of the brecciation event with the local geological record suggests a Paleozoic age of the astrobleme.
CLASSIFICATION OF EIGHT ORDINARY CHONDRITES FROM TEXAS
Authors: Ehlmann Arthur J. , Keil Klaus
Published: June 2012

Based on optical microscopy and electron microprobe analyses, eight previously undescribed or poorly known chondrites were classified into compositional groups, petrologic types, and degree of shock alteration. These chondrites are: Leander, L4b; Nazareth(a), L6d; La Villa, H4b; Mereta, H4c; Gail, H4d; Shafter Lake, H5a; Uvalde, H5d; and Howe, H5d.
POSSIBLE IMPACT SPHERULES FROM NEAR THE BASE OF THE MIDDLE ORDOVICIAN IN NORTHERN ILLINOIS
Authors: Read William F.
Published: June 2012

Angular fragments of a greyish‐white chert‐like rock containing numerous sand‐size spherules believed to be of impact origin have been found in northern Illinois. These fragments, many as large as a man's fist, are recognizable in the field by the presence in them of conspicuous rounded cavities which were probably bubbles. Most have been picked up as float in the bottoms of ravines, but it is clear that they come from near the base of the St. Peter sandstone and that they were already fragments when incorporated in this formation. The original mineralogy of the spherules is obscure because of wholesale replacement by microcrystalline quartz. But the shapes of some of the original minerals have been preserved as pseudomorphs. Judging from the arrangement of these pseudomorphs, and the distribution of opaque material in which they are imbedded, it appears that some spherules attained their present size as liquid droplets. Others apparently solidified as they grew. The original spherule deposit, which must have been at least 15 cm thick in some places, was evidently hot enough, and sufficiently plastic, to permit the formation of large bubbles. It is not clear how the original deposit was broken into fragments.
EVIDENCE FOR SELECTIVE VOLATILIZATION AND IMPERFECT MIXING IN INDOCHINITES
Authors: Ridenour Gregory S.
Published: June 2012

Sixty‐one unbroken, regularly‐shaped indochinites were analyzed for potassium, rubidium, and lithium by flame emission spectrophotometry. Mass and an estimate of surface area (calculated from a specimen's dimensions) were also determined. Two compositional sub‐groups were identified and designated as type N (normal) and type L (low‐alkali) indochinites. For the 56 type N specimens, K, Rb, and Li were all correlated with mass, suggestive that selective volatilization occurred during the formation of indochinites. Correlations were not significantly enhanced by simultaneously considering the effects of both mass and surface area on alkali abundances via multiple regression analysis or the use of a composite independent variable. All possible pairings of K, Rb, and Li were correlated, suggestive that an imperfect mixing process may have occurred during the formation of indochinites. Hotellings t‐test indicated that all inter‐alkali correlations were significantly higher than any of the mass‐alkali correlations. Negative correlations were found for K/Li and Rb/Li vs. Li. These trends may be attributed to 1) the fusion of a parent material that was homogeneous with respect to alkali element ratios that experienced more rapid depletion of the more volatile species of an alkali pair for those tektites with initially higher alkali contents, or 2) the imperfect mixing of a “lithium‐rich” and a “lithium‐poor” component.
FLUORINE AND CHLORINE CONTENTS OF TEKTITES
Authors: Bailey J.C.
Published: June 2012

Fluorine (by combined distillation‐spectrophotometry) and chlorine (by X‐ray fluorescence spectrometry) contents were determined in normal and Muong Nong‐type tektites. Contents of F (78–285 ppm) and Cl (3–44 ppm) in normal tektites are about 4 and 10 times lower, respectively, than in the Earth's continental crust and this is attributed to selective volatilization during impact melting. Muong Nong‐type tektites are characterised by similar F (124–312 ppm) but higher Cl (65–205 ppm) contents and may have resulted from a lower temperature event.
PLASMA CHEMISTRY OF METEORITES—I. CLEANSING AND REDUCTION OF THE ODESSA IRON METEORITE
Authors: Cocke David L. , Rowe M.W.
Published: June 2012

Three small samples of the Odessa, Texas iron meteorite, two surrounded by sandy soil, were introduced into a hydrogen plasma. The soil was effectively cleansed from the iron surfaces, being substantially destroyed with only a fine dust remaining. The appearance of the iron meteorite samples indicated that the terrestrial oxidation was reversed, probably to magnetite, Fe3O4, and metallic iron.
SATURATION MAGNETIZATION MEASUREMENTS OF CARBONACEOUS CHONDRITES
Authors: Hyman M. , Rowe M.W.
Published: June 2012

The saturation magnetization of some carbonaceous chondrites was studied using a Faraday balance. The Faraday balance was shown to be an accurate (± 3%), reliable technique for measuring saturation magnetization by comparison with vibrating‐sample magnetometer measurements on the same samples. Hyman and Rowe (1983) previously used these saturation magnetization measurements to measure the magnetite content of the five CI chondrites. Here, we present measurements on the magnetite contents of some CM2, CV3 and a CV5 chondrites. The method was also used to measure the content of metallic nickel‐iron in Ornans, 3.4 ± 0.3%. Of the CM2 chondrites examined, only Bells, Essebi and Haripura had magnetite contents over about 1% by weight. A number of CV chondrites have magnetite between 2.3 and 13%, with little or no metallic iron. Leoville and Vigarano contain both magnetite and metallic iron, complicating the saturation magnetization results. Arch and Allende have very little metallic iron or magnetite, probably < 1% of either. This technique measures only ferrimagnetic magnetite; superparamagnetic magnetite with particle size < 300Å is ignored.
THE ISOTOPIC COMPOSITION OF TELLURIUM IN THE ABEE METEORITE
Authors: Smith C.L. , De Laeter J.R.
Published: June 2012

Smith et al. (1978) measured the isotopic composition of tellurium in a number of whole rock meteorites by solid source spectrometry and concluded that all the data were identical to a terrestrial standard within experimental errors. However, Oliver et al. (1981) reexamined the data reported by Smith et al. (1978) and argued that, in the case of the Abee meteorite, a negative anomaly in 124Te may be present, supporting the claim for a similar anomaly in Allende. The present work reports two sets of measurements of the tellurium isotopic composition of Abee, and compares the meteoritic data with a terrestrial tellurium standard. No isotopic anomalies can be distinguished within the error limits. However, further work on the isotopic composition of Te in residues from the Allende meteorite need to be pursued by accurate mass spectrometric analysis.
THE VERKHNE DNIEPROVSK IRON METEORITE SPECIMENS IN THE VIENNA COLLECTION AND THE CONFUSION OF VERKHNE DNIEPROVSK WITH AUGUSTINOVKA
Authors: Buchwald V.F. , Clarke Roy S.
Published: June 2012

It is now a hundred years since a small amount of meteoritic material labelled Verkhne Dnieprovsk was first described. Since then the material has been controversial, due to the corroded character and the very limited amount of material known. Authentic samples, totalling 8 g, have been identified in the Vienna collection, which confirm that Verkhne Dnieprovsk is a unique meteorite, both in its composition, belonging to group II E, and in its heavily shocked and distorted structure. The shock‐produced structures include micromelts with a phosphorus gradient, suggesting that the melts originated in situ from mm‐sized schreibersite crystals.

Unfortunately, no additional information as to location and circumstances of find was discovered at this late date. Further work will probably require field work and interviews on the site and/or studies of Russian archives.
CARBON IN DARK INCLUSIONS OF THE ALLENDE METEORITE
Authors: Heymann D. , Van Der Stap C.C.A.H. , Vis R.N. , Verheul H.
Published: June 2012

Carbon contents of three Dark Inclusions (DI's) of the Allende meteorite, measured chemically, range from 0.56 to 1.17 weight %. When one includes the data reported by Bunch, Chang, and Ott (two DI's), the lower limit is 0.44%. The C‐concentration map of a 1.6 × 1.6 mm2 area straddling the boundary of a DI and matrix, or else of a DI and its dark halo, obtained with a 12C (d,p)13 C nuclear microprobe, shows that the C‐content of the core of the DI is very uniform, and that the C‐content of the rim is 2.9 ± 0.3 times larger. Variability of C‐content of matrix and matrix‐like areas of Allende appears to be the rule. DI's cannot be reworked bulk Allende, or precursor for bulk Allende without the addition, respectively removal of significant amounts of carbon. However, some Type 1 DI's might be reworked Allende matrix or precursor matter for that matrix.