Carrier phases for iodine in the Allende meteorite and their associated sup 129 Xe sub r / sup 127 I ratios: A laser microprobe study

Journal Article · Tue Mar 01 04:00:00 EST 1988 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(88)90330-4· OSTI ID:5180246

Kirschbaum, C ^[1]

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1. Univ. of California, Berkeley (USA)

A new mass spectrometer of high sensitivity coupled to a laser microprobe sample extraction system was used to determine the {sup 129}Xe{sub r}/I ratios of minerals which carry {sup 129}Xe{sub r} in the Allende meteorite. In sodalite-rich fine-grained inclusions Ok correlates with Cl verifying that sodalite carries the majority of I. One sample heated above the decomposition point of sodalite had a small amount of residual I indicating the presence of at least one other carrier. The Cl/I ratio of the matrix was different from that of the fine-grained inclusions and the {sup 129}Xe{sub r} correlates with trapped Xe. This implies either a different Cl/I ratio for sodalite in the matrix or a different carrier for I in matrix. In melilite from one coarse-grained inclusion, I is variable and correlates with both Xe and, surprisingly, {sup 131}Xe produced from Ba during the irradiation. In coarse-grained inclusions with Cl-rich alteration products in cracks, most of the {sup 129}Xe{sub r} is found in those cracks. A residual amount of {sup 129}Xe{sub r} is present in melilite samples which show no Cl-rich alteration products, and is a trace impurity in the melilite. The {sup 129}Xe{sub r}/{sup 127}I ratio of sodalite from the fine-grained inclusions, and matrix is similar--between 1.25 and 1.35 {times} 10{sup {minus}4}. This implies an age for these samples within 2 million years of a Bjurbole chondrule included in the irradiation as a standard. The {sup 129}Xe{sub r}/{sup 127}I ratio of a sample of a fine-grained inclusion heated to 1,100{degree}C is 2.4 {times} 10{sup {minus}4} or 16 million years before the Bjurbole chondrule. A coarse-grained inclusion on the other hand showed a {sup 129}Xe{sub r}/{sup 127}I ratio of 3.15 {times} 10{sup {minus}5} or 35 million years after the Bjurbole chondrule.

• OSTI ID: 5180246
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 52:3; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
640106 -- Astrophysics & Cosmology-- Cosmology
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABUNDANCE
CARRIERS
CHEMISTRY
CONCENTRATION RATIO
COSMOCHEMISTRY
ELEMENT ABUNDANCE
ELEMENTS
FLUIDS
GASES
GEOLOGIC HISTORY
HALOGENS
INCLUSIONS
IODINE
ISOTOPE RATIO
MASS SPECTROSCOPY
METEORITES
NONMETALS
RADIONUCLIDE KINETICS
RARE GASES
SPECTROSCOPY
XENON