Meteoritics最新文献

{"title":"Beryllium-10 and Aluminum-26 in Individual Cosmic Spherules from Antarctica","authors":"K. Nishiizumi, J. Arnold, D. Brownlee, M. Caffee, R. Finkel, R. Harvey","doi":"10.1111/J.1945-5100.1995.TB01170.X","DOIUrl":"https://doi.org/10.1111/J.1945-5100.1995.TB01170.X","url":null,"abstract":"— We present data for the cosmogenic nuclides 10Be and 26Al in a suite of 24 extraterrestrial spherules, collected from Antarctic moraines and deep sea sediments. All of the 10 large spherules collected in glacial till at Lewis Cliff are extraterrestrial. As in earlier work, the great majority of particles show prominent solar cosmic-ray (SCR) production of 26Al, indicating bombardment ages on the order of 106 years or even longer. These long ages are in direct contradiction to model ages for small particles in the inner Solar System and may require reconsideration of models of small particle lifetimes. A small fraction of the particles so far measured (6/42) possess cosmogenic radionuclide patterns consistent with predictions for meteoroid spall droplets. We believe that most of the spherules were bombarded in space primarily as bodies not much larger than their present size. \u0000 \u0000 \u0000 \u0000The content of in situ produced 10Be and 26Al in quartz pebbles in the same moraine suggests that these spherules may have on average a significant terrestrial age.","PeriodicalId":81993,"journal":{"name":"Meteoritics","volume":"30 1","pages":"728-732"},"PeriodicalIF":0.0,"publicationDate":"1995-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/J.1945-5100.1995.TB01170.X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63677323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New collections: New frontiers","authors":"P. Benoit","doi":"10.1111/J.1945-5100.1995.TB01157.X","DOIUrl":"https://doi.org/10.1111/J.1945-5100.1995.TB01157.X","url":null,"abstract":"","PeriodicalId":81993,"journal":{"name":"Meteoritics","volume":"30 1","pages":"619-620"},"PeriodicalIF":0.0,"publicationDate":"1995-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/J.1945-5100.1995.TB01157.X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63676735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"No iridium anomaly after the 1908 Tunguska impact: Evidence from a Greenland ice core","authors":"K. Rasmussen, H. B. Clausen, G. Kallemeyn","doi":"10.1111/J.1945-5100.1995.TB01160.X","DOIUrl":"https://doi.org/10.1111/J.1945-5100.1995.TB01160.X","url":null,"abstract":"— We have determined the abundances of Ir and other elements by neutron activation analysis on annual dust samples from an ice core from Site B in the Crete region in central Greenland covering the years 1905–1914. Iridium was detected in all samples, but we found no excess Ir above the background in the years following the Tunguska event. The lack of an Ir anomaly in the years after the Tunguska impact combined with the knowledge of the energy released during the impact and our present knowledge about stratospheric transport implies either a very low Ir content of the impactor or an exceptionally high geocentric velocity for the impactor.","PeriodicalId":81993,"journal":{"name":"Meteoritics","volume":"30 1","pages":"634-638"},"PeriodicalIF":0.0,"publicationDate":"1995-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/J.1945-5100.1995.TB01160.X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63676850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Fayette County, Texas, meteorites","authors":"T. Mccoy, A. J. Ehlmann, K. Keil","doi":"10.1111/J.1945-5100.1995.TB01174.X","DOIUrl":"https://doi.org/10.1111/J.1945-5100.1995.TB01174.X","url":null,"abstract":"— We report the first petrologic examination of all stone meteorites of Fayette County, Texas. The 10 stones represent four or five different fall events. The three recovered Bluff stones represent two falls. Bluff (a), which includes the 145.5-kg Bluff #1 stone, is classified as L5(S4), whereas Bluff (b) is classified as L4(S3) and is represented by a single stone. The studied Cedar stones are classified as H4(S3), and all four Cedar stones appear to define a strewnfield. Round Top (a), classified as L5(S3) and represented by two stones, is unrelated to either Bluff or Cedar. Round Top (b) [H4(S3); 1 stone], whose exact provenance is unknown, might be a transported fragment of the Cedar shower.","PeriodicalId":81993,"journal":{"name":"Meteoritics","volume":"30 1","pages":"776-780"},"PeriodicalIF":0.0,"publicationDate":"1995-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/J.1945-5100.1995.TB01174.X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63677800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Trace‐element concentrations in single circumstellar silicon carbide grains from the Murchison meteorite","authors":"S. Amari, P. Hoppe, E. Zinner, R. Lewis","doi":"10.1111/J.1945-5100.1995.TB01165.X","DOIUrl":"https://doi.org/10.1111/J.1945-5100.1995.TB01165.X","url":null,"abstract":"— Concentrations of the trace elements Mg, Al, Ca, Ti, V, Fe, Sr, Y, Zr, Ba and Ce were determined by ion microprobe mass spectrometry in 60 individual silicon carbide (SiC) grains (in addition, Nb and Nd were determined in 20 of them), from separate KJH (size range 3.4–5.9 μm) of the Murchison carbonaceous meteorite, whose C-, N- and Si-isotopic compositions have been measured before (Hoppe et al., 1994) and provide evidence that these grains are of stellar origin. The selected SiC grains represent all previously recognized subgroups: mainstream (20 < 12C/13C < 120; 200 < 14N/15N; Si isotopes on slope 1.34 line), grains A (12C/13C < 3.5), grains B (3.5 < 12C/13C < 10), grains X (15N excesses, large 28Si excesses) and grains Y (150 < 12C/13C < 260; Si isotopes on slope 0.35 line). Data on these grains are compared with measurements on fine-grained SiC fractions. Trace-element patterns reflect both the condensation behavior of individual elements and the source composition of the stellar atmospheres. A detailed discussion of the condensation of trace elements in SiC from C-rich stellar atmospheres is given in a companion paper by Lodders and Fegley (1995). Elements such as Mg, Al, Ca, Fe and Sr are depleted because their compounds are more volatile than SiC. Elements whose compounds are believed to be more refractory than SiC can also be depleted due to condensation and removal prior to SiC condensation. Among the refractory elements, however, the heavy elements from Y to Ce (and Nd) are systematically enriched relative to Ti and V, indicating enrichments by up to a factor of 14 of the s-process elements relative to elements lighter than Fe. Such enrichments are expected if N-type carbon stars (thermally pulsing AGB stars) are the main source of circumstellar SiC grains. Large grains are less enriched than small grains, possibly because they are from different AGB stars. The trace-element patterns of subgroups such as groups A and B and grains X can at least qualitatively be understood if grains A and B come from J-type carbon stars (known to be lacking in s-process enhancements shown by N-type carbon stars) or carbon stars that had not experienced much dredge-up of He-shell material and if grains X come from supernovae. However, a remaining puzzle is how stars become carbon stars without much accompanying dredge-up of s-process elements.","PeriodicalId":81993,"journal":{"name":"Meteoritics","volume":"30 1","pages":"679-693"},"PeriodicalIF":0.0,"publicationDate":"1995-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/J.1945-5100.1995.TB01165.X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63676693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Detailed abundances of rare earth elements, thorium and uranium in chondritic meteorites: An ICP-MS study","authors":"K. Shinotsuka, H. Hidaka, M. Ebihara","doi":"10.1111/J.1945-5100.1995.TB01166.X","DOIUrl":"https://doi.org/10.1111/J.1945-5100.1995.TB01166.X","url":null,"abstract":"","PeriodicalId":81993,"journal":{"name":"Meteoritics","volume":"96 1","pages":"694-699"},"PeriodicalIF":0.0,"publicationDate":"1995-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/J.1945-5100.1995.TB01166.X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63676942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cristobalite- and tridymite-bearing clasts in Parnallee (LL3) and Farmington (L5)","authors":"J. Bridges, I. Franchi, R. Hutchison, A. Morse, J. Long, C. Pillinger","doi":"10.1111/J.1945-5100.1995.TB01169.X","DOIUrl":"https://doi.org/10.1111/J.1945-5100.1995.TB01169.X","url":null,"abstract":"— A set of cristobalite- and tridymite-rich igneous clasts (CB1 to CB8) have been found in Parnallee (LL3.6). They consist of clinoenstatite, minor feldspathic mesostasis and cristobalite veined by endiopsideaugite. The largest clast, CB8, is 1.6 cm in diameter and contains veined tridymite and cristobalite, clinoenstatite (zoned to ferroaugite and pyroxferroite Fs75.6Wo20.0) and plagioclase. Compared to bulk ordinary chondrites (OC), the bulk clasts are depleted in Al (0.02–0.8× OC), Na and K and enriched in Si (1.6–2.0× OC) and Ca (1.3–4.5× OC). Bulk CB8 has LREE > HREE (La/Lu = 1.6) with a positive Eu anomaly (Eu/Eu* = 2.4). Textural observations suggest that the clasts cooled rapidly (24–420 °C/h) above 1200 °C. Clasts CB1—CB8 contain the isotopically heaviest O yet found in ordinary chondrites (up to δ17O = +8.7%o, δ18O = +11.6%o). Enrichment in the heavy isotopes of O is dependent on the proportion of cristobalite (or tridymite) in the clasts. A regression line CRIL (Cristobalite Line), with slope 0.77, is defined by the isotopic compositions of CB1—CB8, the Farmington clast and ordinary chondrite chondrules. An 16O-poor gas reservoir, whose composition must lie at some point along the extension of CRIL, has undergone varying degrees of isotopic exchange with most ordinary chondrite material. Silica polymorphs have undergone the greatest degree of exchange because of their open, framework structures. Silicon in CB1—CB8 has normal isotopic ratios. A model is proposed that involves differentiation of H-group material through extraction of volatile elements in a vapour phase, loss of an Fe-Ni-S melt and metastable crystallisation (60–70%) of olivine. The calculated residual liquid is silica-oversaturated and its subsequent predicted crystallisation sequence resembles that preserved in CB1—CB8. This model may require two stages of heating, the second one prior to cristobalite crystallisation (if the silica polymorph crystallises within its predicted stability field of > 1500 °C). Isotopic exchange took place either when CB1—CB8 were ejected from their parent body due to impact or near the surface of the parent body, perhaps in an ejecta blanket setting. The latter option is preferred because it is more consistent with our igneous model.","PeriodicalId":81993,"journal":{"name":"Meteoritics","volume":"30 1","pages":"715-727"},"PeriodicalIF":0.0,"publicationDate":"1995-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/J.1945-5100.1995.TB01169.X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63677284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Meteoritical Bulletin, No. 78, 1995 November*","authors":"F. Wlotzka","doi":"10.1111/J.1945-5100.1995.TB01177.X","DOIUrl":"https://doi.org/10.1111/J.1945-5100.1995.TB01177.X","url":null,"abstract":"— This Meteoritical Bulletin lists 53 meteorites, of which 16 are from the Nullarbor, Australia, and 12 from Roosevelt County, New Mexico. Besides ordinary chondrites, there are five irons and one howardite (Mundrabilla 018). Four of the meteorites are falls (Baszkowka, Campos Salos, Neagari, and New Halfa).","PeriodicalId":81993,"journal":{"name":"Meteoritics","volume":"232 1","pages":"792-796"},"PeriodicalIF":0.0,"publicationDate":"1995-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/J.1945-5100.1995.TB01177.X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63677725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Noble gases and strontium isotopes in the unique meteorite Divnoe","authors":"Y. Shukolyukov, S. Assonov, M. Smoliar, E. Kolesnikov","doi":"10.1111/J.1945-5100.1995.TB01163.X","DOIUrl":"https://doi.org/10.1111/J.1945-5100.1995.TB01163.X","url":null,"abstract":"Abstract— We present an isotope study of noble gases in Divnoe, an anomalous meteorite, and also Rb-Sr and K-Ar dating of this meteorite. The relatively young Rb-Sr age obtained (3.39 Ga) seems doubtful and, most probably, results from weathering or contamination. The ancient K-Ar age (4.67+0.20–0.40), together with clear excess of 129Xe, allows the suggestion of very early formation of the Divnoe meteorite. \u0000 \u0000Concentrations and isotope ratios of noble gases in Divnoe are: 17.9 ≤ 3He ≤ 29.0 × 10−8; 20Ne = 6.22 × 10−8; 2.44 ≤ 36Ar ≤ 5.10 × 10−8; 130Xe = 41.3 × 10−12 cm3/g; 0.079 ≤ 3He/4He ≤ 0.193; 20Ne/22Ne = 0.860; 21Ne/22Ne = 0.927; 3.47 ≤ 40Ar/36Ar ≤ 9.47; 2.22 ≤ 36Ar/38Ar ≤ 3.27; 129Xe/132Xe = 1.09. The exposure age calculated from cosmogenic 3He, 21Ne, and 38Ar is 17.9 ± 0.9 Ma. \u0000 \u0000On the basis of the isotope data for the noble gases and O, and abundances of K, Rb, and Sr, an attempt was made to estimate the relationship of Divnoe to other meteorite types. The O-isotope characteristics of Divnoe are clearly distinct from those of ordinary chondrites, acapulcoites/lodranites, and SNC meteorites (Petaev et al., 1994, Clayton, 1993). In plots of 136Xe vs.129Xe/130Xe, the Divnoe data fall outside of the data fields for carbonaceous and enstatite chondrites. The light noble gas data, especially the 40Ar/38Ar ratio, and the 40Ar, 38Ar, 3He, and 4He contents of Divnoe differ significantly from those of all meteorite types except diogenites. The K, Rb, and Sr abundances in Divnoe are substantially lower than in most other meteorites. In the concentrations of these elements, as well as in the REE pattern, the Divnoe meteorite is similar only to diogenites. Divnoe probably should be treated as a restite remaining after partial melting of the chondritic mantle of a parent asteroid body.","PeriodicalId":81993,"journal":{"name":"Meteoritics","volume":"30 1","pages":"654-660"},"PeriodicalIF":0.0,"publicationDate":"1995-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/J.1945-5100.1995.TB01163.X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63676500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chemical studies of H chondrites — 7. Contents of Fe3+ and labile trace elements in Antarctic samples","authors":"S. Wolf, M. Lipschutz","doi":"10.1111/J.1945-5100.1995.TB01158.X","DOIUrl":"https://doi.org/10.1111/J.1945-5100.1995.TB01158.X","url":null,"abstract":"— Linear discriminant analysis and logistic regression have been applied to concentration data for 10 labile trace elements (Rb, Ag, Se, Cs, Te, Zn, Cd, Bi, Tl and In) in 33 Antarctic H4–6 chondrites. The proportion of bulk Fe in the Fe3+ state, Fe3+/Fe, of these same chondrites permit their assignment to less- and more-weathered suites. Wherever the division between these suites is placed, the results are identical and consistent with the null hypothesis that the suites sample a single preterrestrial compositional population. Hence, no evidence exists that preterrestrial contents of labile trace elements in Antarctic H4–6 chondrites have been significantly altered by weathering as quantified by Fe3+/Fe or the A-B-C weathering index.","PeriodicalId":81993,"journal":{"name":"Meteoritics","volume":"30 1","pages":"621-624"},"PeriodicalIF":0.0,"publicationDate":"1995-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/J.1945-5100.1995.TB01158.X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"63676786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}