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Title: Structure analysis and conditions of formation of akimotoite in the Tenham chondrite

Authors:
ORCiD logo [1]; ORCiD logo [2];  [3];  [4]
  1. Department of Geoscience, University of Nevada, Las Vegas Nevada 89154-4010 USA
  2. Division of Geology and Planetary Sciences, California Institute of Technology, Pasadena California 91125 USA
  3. Center for Advanced Radiation Sources, University of Chicago, Chicago Illinois 60637 USA, Institut für Geologie und Mineralogie, Universität zu Köln, 4705619 Köln Germany
  4. Center for Advanced Radiation Sources, University of Chicago, Chicago Illinois 60637 USA
Publication Date:
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1413059
Grant/Contract Number:
NA0001974; FG02-94ER14466
Resource Type:
Journal Article: Published Article
Journal Name:
Meteoritics and Planetary Science
Additional Journal Information:
Related Information: CHORUS Timestamp: 2017-12-12 23:33:26; Journal ID: ISSN 1086-9379
Publisher:
Wiley-Blackwell
Country of Publication:
United States
Language:
English

Citation Formats

Tschauner, O., Ma, C., Prescher, C., and Prakapenka, V. B.. Structure analysis and conditions of formation of akimotoite in the Tenham chondrite. United States: N. p., 2017. Web. doi:10.1111/maps.13009.
Tschauner, O., Ma, C., Prescher, C., & Prakapenka, V. B.. Structure analysis and conditions of formation of akimotoite in the Tenham chondrite. United States. doi:10.1111/maps.13009.
Tschauner, O., Ma, C., Prescher, C., and Prakapenka, V. B.. 2017. "Structure analysis and conditions of formation of akimotoite in the Tenham chondrite". United States. doi:10.1111/maps.13009.
@article{osti_1413059,
title = {Structure analysis and conditions of formation of akimotoite in the Tenham chondrite},
author = {Tschauner, O. and Ma, C. and Prescher, C. and Prakapenka, V. B.},
abstractNote = {},
doi = {10.1111/maps.13009},
journal = {Meteoritics and Planetary Science},
number = ,
volume = ,
place = {United States},
year = 2017,
month =
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1111/maps.13009

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  • One hundred and forty individual SiC grains (1-9.6 {mu}m) and twenty-two grain aggregates (2.3-7.8 {mu}m) from the Orgueil (CI) chondrite have been measured by ion microprobe. Silicon and carbon isotopic data were obtained for all individual grains and aggregates, and nitrogen, magnesium, and aluminum abundances and isotopic compositions were measured for most grains and aggregates. Abundances of lithium, beryllium, boron, and sodium were measured for some individual grains. Orgueil SiC is remarkably similar to Murchison K-series SiC in the ranges and distributions of silicon and carbon isotopic compositions, the initial abundances of {sup 26}Al, the abundances of minor and tracemore » elements, and the proportions of isotopically unusual grains. Higher {sup 15}N/{sup 14}N ratios in 1-4 {mu}m Murchison K-series SiC grains relative to similar-sized Orgueil grains are inferred to be due to higher amounts of terrestrial nitrogen in the Murchison samples. Higher {sup 15}N/{sup 14}N ratios in 3-6 {mu}m Murchison KJH SiC grains cannot be explained by terrestrial nitrogen and imply that largers SiC grains sampled a different population of parent stars. SiC aggregates have different average silicon and carbon compositions than individual grains, indicating different source stars for the 0.1-1 {mu}m constituent grains. However, the aggregates probably formed by clumping of small grains during laboratory procedures, not at the stellar source. Differences between Murchison L-series SiC and SiC from Murchison K-series and Orgueil are due to the presence of terrestrial SiC among L-series grains and to the larger average grain size of L-series SiC. When terrestrial contamination, sample size, and grain size are taken into account, there is no evidence of an intrinsic difference between Orgueil and Murchison SiC. The Orgueil data provide new information about stellar nucleosynthesis and the SiC parent stars.« less
  • Isotopic analysis of nesquehonite recovered from the surface of the LEW 85320 H5 ordinary chondrite shows that the delta C-13 and delta O-18 values of the two generations of bicarbonate (Antarctic and Texas) are different: delta C-13 = + 7.9 per mil and + 4.2 per mil; delta O-18 = + 17.9 per mil and + 12.1 per mil, respectively. Carbon isotopic compositions are consistent with equilibrium formation from atmospheric carbon dioxide at - 2 + or - 4 C (Antarctic) and + 16 + or - 4 C (Texas). Oxygen isotopic data imply that the water required for nesquehonitemore » precipitation was derived from atmospheric water vapor or glacial meltwater which had locally exchanged with silicates, either in the meteorite or in underlying bedrock. Although carbonates with similar delta C-13 values have been identified in the SNC meteorites EETA 79001 and Nakhla, petrographic and temperature constraints argue against their simply being terrestrial weathering products. 35 refs.« less