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Chemical fractionations in meteorites. IX. C3 chondrites

Abstract

Four C3V chondrites (Grosnaja, Kaba, Mokoia, Vigarano) and three C30 chondrites (Felic, Kainsaz, and Lance) were analyzed by radiochemical neutron activation for 17 trace elements. Both classes show a typical chondritic step pattern, reflecting loss of volatiles during chondrule formation. Elements condensing above 1300 K (U, Re, Ir, Ni) are present in essentially C1 chondrite proportions, while moderately volatile elements condensing between 1300 K and 800 K (Ge, Rb, Ag) are depleted by a factor of 0.44. However, elements condensing below 700 K (S, Cs, Bi, Tl, Br, Se, Te, In, Cd) are depleted to a still greater degree, and more so in the Ornans subclass (factor of 0.24, except Cd 0.007) than in the Vigarano subclass (factor of 0.29). This additional depletion may be due to a slight (less than 3-fold) dust-gas fractionation, by settling of dust to the median plane of the solar nebula. Among other chondrite classes, ordinary chondrites show a similar depletion, but C2 chondrites do not. Possibly the undepleted meteorites formed in one of the convection zones of the nebula predicted by Cameron and Pine, whereas the depleted meteorites formed in a quiescent region. The condensation of chalocophile elements as a function of H/sub 2/S  More>>
Authors:
Anders, E; Higuchi, H; Ganapathy, R; Morgan, J W [1] 
  1. Chicago Univ., Ill. (USA). Enrico Fermi Inst.
Publication Date:
Sep 01, 1976
Product Type:
Journal Article
Reference Number:
AIX-07-274764; EDB-77-019176
Resource Relation:
Journal Name: Geochim. Cosmochim. Acta; (United Kingdom); Journal Volume: 40:9
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CHONDRITES; ACTIVATION ANALYSIS; CHEMICAL COMPOSITION; ANTIMONY; BISMUTH; BROMINE; CADMIUM; CESIUM; GERMANIUM; GOLD; INDIUM; IRIDIUM; NEUTRONS; NICKEL; PLANET-SYSTEM ACCRETION; QUANTITATIVE CHEMICAL ANALYSIS; RHENIUM; RUBIDIUM; SELENIUM; SILVER; SOLAR SYSTEM EVOLUTION; TELLURIUM; THALLIUM; TRACE AMOUNTS; URANIUM; ACTINIDES; ALKALI METALS; BARYONS; CHEMICAL ANALYSIS; ELEMENTARY PARTICLES; ELEMENTS; FERMIONS; HADRONS; HALOGENS; METALS; METEORITES; NONMETALS; NUCLEONS; PLATINUM METALS; REFRACTORY METALS; SEMIMETALS; STONE METEORITES; TRANSITION ELEMENTS; 400101* - Activation, Nuclear Reaction, Radiometric & Radiochemical Procedures; 640100 - Astrophysics & Cosmology
OSTI ID:
7246246
Country of Origin:
United Kingdom
Language:
English
Other Identifying Numbers:
Journal ID: CODEN: GCACA
Submitting Site:
INIS
Size:
Pages: 1131-1139
Announcement Date:

Citation Formats

Anders, E, Higuchi, H, Ganapathy, R, and Morgan, J W. Chemical fractionations in meteorites. IX. C3 chondrites. United Kingdom: N. p., 1976. Web. doi:10.1016/0016-7037(76)90054-5.
Anders, E, Higuchi, H, Ganapathy, R, & Morgan, J W. Chemical fractionations in meteorites. IX. C3 chondrites. United Kingdom. doi:10.1016/0016-7037(76)90054-5.
Anders, E, Higuchi, H, Ganapathy, R, and Morgan, J W. 1976. "Chemical fractionations in meteorites. IX. C3 chondrites." United Kingdom. doi:10.1016/0016-7037(76)90054-5. https://www.osti.gov/servlets/purl/10.1016/0016-7037(76)90054-5.
@misc{etde_7246246,
title = {Chemical fractionations in meteorites. IX. C3 chondrites}
author = {Anders, E, Higuchi, H, Ganapathy, R, and Morgan, J W}
abstractNote = {Four C3V chondrites (Grosnaja, Kaba, Mokoia, Vigarano) and three C30 chondrites (Felic, Kainsaz, and Lance) were analyzed by radiochemical neutron activation for 17 trace elements. Both classes show a typical chondritic step pattern, reflecting loss of volatiles during chondrule formation. Elements condensing above 1300 K (U, Re, Ir, Ni) are present in essentially C1 chondrite proportions, while moderately volatile elements condensing between 1300 K and 800 K (Ge, Rb, Ag) are depleted by a factor of 0.44. However, elements condensing below 700 K (S, Cs, Bi, Tl, Br, Se, Te, In, Cd) are depleted to a still greater degree, and more so in the Ornans subclass (factor of 0.24, except Cd 0.007) than in the Vigarano subclass (factor of 0.29). This additional depletion may be due to a slight (less than 3-fold) dust-gas fractionation, by settling of dust to the median plane of the solar nebula. Among other chondrite classes, ordinary chondrites show a similar depletion, but C2 chondrites do not. Possibly the undepleted meteorites formed in one of the convection zones of the nebula predicted by Cameron and Pine, whereas the depleted meteorites formed in a quiescent region. The condensation of chalocophile elements as a function of H/sub 2/S partial pressure is discussed, in an attempt to explain the drastic difference in Cd abundance between the two subclasses. It appears that the H/sub 2/S/H/sub 2/ ratio is the key variable. C30's seem to have condensed in a region where enough metallic Fe was present to buffer the H/sub 2/S pressure, while C3V's condensed in a more oxidized region, where H/sub 2/S was in excess. Accretion temperatures, for an assumed nebular pressure of 10/sup -5/ atm, were between 415 and 430 K for C30's and less than 440 K for CeV's.}
doi = {10.1016/0016-7037(76)90054-5}
journal = {Geochim. Cosmochim. Acta; (United Kingdom)}
volume = {40:9}
journal type = {AC}
place = {United Kingdom}
year = {1976}
month = {Sep}
}