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Title: Recondite interstellar carbon components in the allende meteorite revealed by preparative precombustion

Abstract

Prolonged combustion at low temperatures (390-450{degree}C and 450-510{degree}C) removes large quantities of isotopically normal carbon from an acid (HF/HCl) residue of the Allende meteorite to reveal two isotopically heavy carbon components. One of them, called C{sub {aleph}} (carbon aleph) because of its possible relationship to C{sub {alpha}} of the host of Ne-E(L), has {delta}{sup 13}C of +345{per thousand} and a combustion temperature of 700-750{degree}C. It is believed that the presence of C{sub {aleph}} is masked in the bulk acid residue because of a tailing effect in the combustion of less stable forms of carbon. The second heavy carbon component burns over the temperature regime 900-1000{degree}C and has a {delta}{sup 13}C of > 527{per thousand}. This component called C{sub {kappa}} (carbon kappa) is distinguishable from the well known types of heavy carbon called C{sub {beta}} and C{sub {epsilon}}, the hosts of s-Xe and NeE(H), respectively, and now recognized as forms of SiC. C{sub {kappa}}, however, could also be a form of very poorly crystalline SiC; it appears to be released from the Allende acid residue because the precombustion slowly degrades a secondary hot mineral, which is possibly a variety of spinel. Likewise, a component of light carbon, possibly C{sub {theta}}, poorlymore » crystalline graphite, is also liberated by the precombustion reaction after between 52 and 108 h of treatment. The discovery of C{sub {aleph}}, C{sub {kappa}}, and C{sub {theta}}, together with C{sub {lambda}}, a component very rich in {sup 12}C confirms that primitive meteorites are a prolific source of interstellar grains. Preparative precombustion demonstrates that the legacy to be found in Allende is far more complicated than at first envisaged from the noble gas record of this meteorite.« less

Authors:
; ; ;  [1];  [2]
  1. Open Univ., Milton Keynes (England)
  2. Univ. of Oxford (England)
Publication Date:
OSTI Identifier:
7188865
Resource Type:
Journal Article
Journal Name:
Geochimica et Cosmochimica Acta; (USA)
Additional Journal Information:
Journal Volume: 54:2; Journal ID: ISSN 0016-7037
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; METEORITES; PYROLYTIC CARBON; CHEMICAL ANALYSIS; ACIDIFICATION; CARBON COMPOUNDS; CHEMICAL COMPOSITION; PYROLYSIS PRODUCTS; SPINELS; ALKALINE EARTH METAL COMPOUNDS; ALUMINIUM COMPOUNDS; ALUMINIUM OXIDES; CARBON; CHALCOGENIDES; ELEMENTS; MAGNESIUM COMPOUNDS; MAGNESIUM OXIDES; MINERALS; NONMETALS; OXIDE MINERALS; OXIDES; OXYGEN COMPOUNDS; 580000* - Geosciences; 640106 - Astrophysics & Cosmology- Cosmology

Citation Formats

Ash, R D, Grady, M M, Wright, I P, Pillinger, C T, and Arden, J W. Recondite interstellar carbon components in the allende meteorite revealed by preparative precombustion. United States: N. p., 1990. Web. doi:10.1016/0016-7037(90)90333-G.
Ash, R D, Grady, M M, Wright, I P, Pillinger, C T, & Arden, J W. Recondite interstellar carbon components in the allende meteorite revealed by preparative precombustion. United States. doi:10.1016/0016-7037(90)90333-G.
Ash, R D, Grady, M M, Wright, I P, Pillinger, C T, and Arden, J W. Thu . "Recondite interstellar carbon components in the allende meteorite revealed by preparative precombustion". United States. doi:10.1016/0016-7037(90)90333-G.
@article{osti_7188865,
title = {Recondite interstellar carbon components in the allende meteorite revealed by preparative precombustion},
author = {Ash, R D and Grady, M M and Wright, I P and Pillinger, C T and Arden, J W},
abstractNote = {Prolonged combustion at low temperatures (390-450{degree}C and 450-510{degree}C) removes large quantities of isotopically normal carbon from an acid (HF/HCl) residue of the Allende meteorite to reveal two isotopically heavy carbon components. One of them, called C{sub {aleph}} (carbon aleph) because of its possible relationship to C{sub {alpha}} of the host of Ne-E(L), has {delta}{sup 13}C of +345{per thousand} and a combustion temperature of 700-750{degree}C. It is believed that the presence of C{sub {aleph}} is masked in the bulk acid residue because of a tailing effect in the combustion of less stable forms of carbon. The second heavy carbon component burns over the temperature regime 900-1000{degree}C and has a {delta}{sup 13}C of > 527{per thousand}. This component called C{sub {kappa}} (carbon kappa) is distinguishable from the well known types of heavy carbon called C{sub {beta}} and C{sub {epsilon}}, the hosts of s-Xe and NeE(H), respectively, and now recognized as forms of SiC. C{sub {kappa}}, however, could also be a form of very poorly crystalline SiC; it appears to be released from the Allende acid residue because the precombustion slowly degrades a secondary hot mineral, which is possibly a variety of spinel. Likewise, a component of light carbon, possibly C{sub {theta}}, poorly crystalline graphite, is also liberated by the precombustion reaction after between 52 and 108 h of treatment. The discovery of C{sub {aleph}}, C{sub {kappa}}, and C{sub {theta}}, together with C{sub {lambda}}, a component very rich in {sup 12}C confirms that primitive meteorites are a prolific source of interstellar grains. Preparative precombustion demonstrates that the legacy to be found in Allende is far more complicated than at first envisaged from the noble gas record of this meteorite.},
doi = {10.1016/0016-7037(90)90333-G},
journal = {Geochimica et Cosmochimica Acta; (USA)},
issn = {0016-7037},
number = ,
volume = 54:2,
place = {United States},
year = {1990},
month = {2}
}