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Published May 1977 | public
Journal Article

Neon and argon in the Allende meteorite

Abstract

Trapped and cosmogenic Ne and Ar were measured in Ca,Al-rich aggregates and chondrules, mafic chondrules, and bulk and matrix samples from the Allende C3V chondritic meteorite to investigate the possible occurrence of anomalous isotopic compositions of noble gases that would correlate with oxygen or magnesium isotopic anomalies previously found in this meteorite. Large enrichments of both ^(22)Ne and ^(36)Ar were observed in low-temperature release fractions from several Ca,Al-rich inclusions, but the enrichments are consistent with galactic cosmic-ray production of 22Ne by spallation from sodium and ^(36)Ar by neutron capture on chlorine. Trapped neon in matrix samples is comprised of two distinctive compositions, with (^(20)Ne/^(22)Ne)_t equal to 8.7 ± 0.1 and 10.4 ± 1.0, that appear to correlate with the two gas-rich trace phases chromite/carbon and 'Q' described by Lewis et al. (1975). Several Ca,Al-rich aggregates which have high contents of the volatile elements Na, Cl, K, and Rb also contain trapped neon. However, no neon-E has been identified in any of the samples studied, including samples of several inclusions known to contain isotopically anomalous oxygen and magnesium.

Additional Information

© 1977 Pergamon Press. Received 18 May 1976; accepted in revised form 1 December 1976. We gratefully acknowledge constructive criticism provided in a review of this manuscript by D. PHINNEY. This work was supported by NSF grants GP-28027 and MPS71-02670 A05.

Additional details

Created:
August 19, 2023
Modified:
October 25, 2023