The Noble Gas Record in Antarctic and Other Meteorites

Abstract Data are reported for the concentration and isotopic composition of He, Ne, and Ar in 11 Antarctic and 8 other stone meteorites. Cosmic ray exposure ages and whole rock gas retention model ages are given. The noble gas record suggests that all three ALLAN HILLS eucrites analysed so far belong to the same meteorite fall while the three eucrites from the ELEPHANT MORAINE area appear to be three independent individual falls.

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Noble Gas Record of Japanese Chondrites

Zeitschrift für Naturforschung A ◽

10.1515/zna-1989-1006 ◽

1989 ◽

Vol 44 (10) ◽

pp. 935-944

Author(s):

Nobuo Takaoka ◽

Masako Shima ◽

Fumitaka Wakabayashi

Keyword(s):

Noble Gas ◽

Cosmic Ray ◽

Ordinary Chondrites ◽

Isotopic Signatures ◽

Shock Heating ◽

H Chondrites ◽

Gas Loss ◽

Exposure Ages ◽

Cosmic Ray Exposure Ages ◽

Gas Component

Abstract Concentrations and isotopic ratios of noble gases are reported for nineteen Japanese chondrites. Among those, Nio (H3-4) is a solar-gas-rich meteorite.U/Th - He ages are younger than K - Ar ages for all meteorites studied. Six of the nine L-chondrites give significantly young K-Ar ages, suggesting gas loss by impact shock heating. The remaining three L-chondrites and seven of the ten H-chondrites have K-Ar ages older than 4 Ga. The L-chondrite Nogata and the H-chondrites Numakai, Ogi and Higashi-Koen have concordant ages.Cosmic-ray exposure ages for six of the H-chondrites show clustering around the 6-Myr peak in the distribution of exposure ages, while those for the L-chondrites, ranging from 8.2 to 64 Myr, do not show clustering.Fukutomi (L4) contains trapped 36Ar in excess, 3.5 times enriched compared to the highest value so far reported for type-4 ordinary chondrites except solar-gas-rich chondrites. The 36Ar/132Xe and 84Kr/132Xe ratios fit along a mixing line between a planetary and a sub-solar (or argon-rich) component found in separates of E-chondrites [43], The Xe isotopic composition is identical with that in Abee and Kenna. The isotopic signatures suggest that this meteorite may contain mineral fragments bearing the noble gas component found in E-chondrites or ureilites. Fukutomi also contains 80Kr, 82Kr and 128Xe produced by epithermal neutron captures on 79Kr, 81Kr and 127I, respectively. From the neutron-produced Kr, the preatmospheric minimum radius is estimated to be 20 cm with an assumption of a spherical meteoroid.

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Relationships among lodranites and acapulcoites: noble gas isotopic abundances, chemical composition, cosmic-ray exposure ages, and solar cosmic ray effects

Geochimica et Cosmochimica Acta ◽

10.1016/s0016-7037(99)00012-5 ◽

1999 ◽

Vol 63 (2) ◽

pp. 175-192 ◽

Cited By ~ 28

Author(s):

Andreas Weigel ◽

Otto Eugster ◽

Christian Koeberl ◽

Rolf Michel ◽

Urs Kr̈ahenb̈uhl ◽

...

Keyword(s):

Chemical Composition ◽

Noble Gas ◽

Cosmic Ray ◽

Isotopic Abundances ◽

Ray Effects ◽

Exposure Ages ◽

Cosmic Ray Effects ◽

Cosmic Ray Exposure Ages

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Über den Helium- und Neongehalt von Steinmeteoriten und deren radiogene und kosmogene Alter

Zeitschrift für Naturforschung A ◽

10.1515/zna-1962-1210 ◽

1962 ◽

Vol 17 (12) ◽

pp. 1092-1102 ◽

Cited By ~ 1

Author(s):

H. Hintenberger ◽

H. König ◽

H. Wanke

Keyword(s):

Neutron Activation ◽

Isotopic Composition ◽

Total Content ◽

Cosmic Ray ◽

Decay Rates ◽

Chemical Compositions ◽

Diffusion Loss ◽

Helium 3 ◽

Exposure Ages ◽

Cosmic Ray Exposure Ages

The total content as well as the isotopic composition of helium and neon of 19 chondrites and 5 achondrites have been determined. A description of the analytical method is given. Large variations of the ratios 3He/21Ne were observed and it is shown that these variations cannot be explained by differences in the chemical compositions of the meteorites only.Radiogenic helium ages and cosmic ray exposure ages have been calculated. The calculation of the helium ages was mainly based on uranium determinations by means of the xenon-method previously developed in this laboratory. The radiogenic helium ages range from 0.42 · 109 to 4.5 · 109 years. The values obtained for the helium ages are compared with the figures for the potassium-argon ages formerly derived by a neutron activation method newly developed and of those stated in the literature. It turns out that in most cases the radiogenic helium ages are lower, sometimes considerably lower than the potassium-argon ages indicating diffusion loss of helium and certainly in smaller quantities also of argon.Using tritium and sodium 22 decay rates from the literature for the calculations of the production rates for helium 3 and neon 22 cosmic ray exposure ages for all the meteorites analysed were obtained. These exposure ages vary between 0.3 ·106 and 29·106 years. No correlation between radiogenic ages and cosmic ray exposure ages and no grouping of the exposure ages have been found.

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Noble gas concentrations and cosmic ray exposure ages of eight recently fallen chondrites

Geochimica et Cosmochimica Acta ◽

10.1016/0016-7037(73)90289-5 ◽

1973 ◽

Vol 37 (11) ◽

pp. 2417-2433 ◽

Cited By ~ 23

Author(s):

D.D Bogard ◽

M.A Reynolds ◽

L.A Simms

Keyword(s):

Noble Gas ◽

Cosmic Ray ◽

Exposure Ages ◽

Cosmic Ray Exposure Ages

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Radiogene, spallogene und primordiale Edelgase in Steinmeteoriten III

Zeitschrift für Naturforschung A ◽

10.1515/zna-1965-0801 ◽

1965 ◽

Vol 20 (8) ◽

pp. 983-989 ◽

Cited By ~ 1

Author(s):

H. Hintenberger ◽

H. König ◽

L. Schultz ◽

H. Wanke

Keyword(s):

Isotopic Composition ◽

Total Content ◽

Cosmic Ray ◽

Gas Content ◽

Rare Gas ◽

Rare Gases ◽

Gas Measurements ◽

Exposure Ages ◽

Cosmic Ray Exposure Ages

The total content as well as the isotopic composition of helium and neon of 36 stone meteorites have been determined. Except for meteorites with primordial rare gas content, the radiogenic component of 4He has been calculated by subtracting the fourfold amount of 3He from the total 4He in order to allow for the spallation fraction of 4He. From the content of radiogenic 4He the U-Th-He-ages of the investigated meteorites have been calculated.From the content of 3He and 21Ne cosmic ray exposure ages were calculated for all meteorites also.With the new data of the 36 stone meteorites, presented in this paper, the total number of stone meteorites, of which rare gas measurements were carried out so far, amounts to 70 bronzitechondrites and 93 hypersthene-chondrites. The earlier indications for marked differences in the distribution of the U-Th-He-ages as well as for the cosmic ray exposure ages between the bronzitechondrites and the hypersthene-chondrites proved to be undoubtedly correct.During our investigations, we found Elm Creek as one additional bronzite-diondrite with high amounts of primordial rare gases. In two other bronzite-chondrites (Cavour and Dimmit) primordial rare gases were also detected, but in rather small amounts.

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