Extremely NA and CL Rich Chondrule AL3509 from the Allende Meteorite [electronic resource]
We report on the mineralogy, petrology, chemistry, oxygen isotopes, ²⁶Al-²⁶Mg and ³⁶Cl-³⁶S isotope systematics of the Allende chondrule Al3509 discovered and described by [1] and [2]. This spherical object (≈1cm φ) contains ≈10% Na and 1% Cl, and nearly pure ¹²⁹Xe [(¹²⁹Xe/¹²⁷I) = 1.1 x 10⁻⁴ (3)]. Th...
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Online Access |
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| Format: | Government Document Electronic eBook |
| Language: | English |
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Washington, D.C : Oak Ridge, Tenn. :
United States. Dept. of Energy ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy,
2011.
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| Summary: | We report on the mineralogy, petrology, chemistry, oxygen isotopes, ²⁶Al-²⁶Mg and ³⁶Cl-³⁶S isotope systematics of the Allende chondrule Al3509 discovered and described by [1] and [2]. This spherical object (≈1cm φ) contains ≈10% Na and 1% Cl, and nearly pure ¹²⁹Xe [(¹²⁹Xe/¹²⁷I) = 1.1 x 10⁻⁴ (3)]. This high enrichment in halogens makes it of interest in searching for radiogenic ³⁶S from ³⁶Cl (t₁₂ ≈ 0.3 Ma) decay. While there is strong evidence for the presence of ³⁶Cl in sodalite and wadalite in CV CAIs [4,5], some sodalites show no evidence for excesses of ³⁶S (³⁶S*). In contrast, high inferred initial ³⁶Cl/³⁵Cl = 2 x 10⁻⁵ has been found in wadalite from the Allende CAI AJEF [5]. The observed ³⁶S excesses in sodalite are not correlated with radiogenic ²⁶Mg, decay product of ²⁶Al (t₁₂ ≈ 0.72 Ma) [4]. From the inferred initial ³⁶Cl/³⁵Cl ratios and consideration of both AGB and SNe stellar sources, ³⁶Cl must be the product of charged particle irradiation within the early solar system. However, neither the specific nuclear production mechanism nor the irradiation site have been identified. Both sodalite and wadalite are found as late stage alteration products of CAIs together with grossular, monticellite, Al-rich pyroxene, wollastonite, nepheline, ferroan olivine, and ferroan pyroxenes. This late-stage alteration has been found to extensively change some CAIs in Allende, but clear residues of spinel, hibonite and Wark-Lovering rims are recognizable remnants of the original CAIs. The nature of the widespread volatile alteration process as well as that of the fluid phase remain controversial. |
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| Item Description: | Published through the Information Bridge: DOE Scientific and Technical Information. 04/07/2011. "llnl-conf-479981" Presented at: 42nd Lunar and Planetary Science COnference (2011), The Woodlands, TX, United States, Mar 07 - Mar 11, 2011. Hutcheon, I D; Nagashima, K; Wasserburg, G J; Aleon, J; Ramon, E C; Krot, A N; Brearley, A J. |
| Physical Description: | PDF-file: 4 pages; size: 0.3 Mbytes. |