Rare earth abundances in chondritic phosphates and their implications for early stage chronologies

Mitsuru Ebihara, Masatake Honda

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

The abundances of nine rare earth elements (REE) in phosphate separates from three ordinary chondrites, Saint Séverin (LL6), Bruderheim (L6) and Richardton (H5), were measured by instrumental neutron activation analysis. All REE except europium are enriched in the phosphate minerals (merrillite and chlorapatite) by factor of 200-300 relative to the chondritic average, whereas Eu is enriched by a factor of 40-50. Electron microprobe analysis showed no significant differences in phosphate mineral composition among the three chondrites studied, though the relative proportions of two minerals varied. According to our data, REE are enriched by almost the same factor in merrillite and chlorapatite in the Bruderheim and, with less certainty, in the other two chondrites. This behavior of REE contrast with that of the actinoid elements, Th, U and Pu, which are also enriched in phosphate but are fractionated between merrillite and chlorapatite. Since Pu and REE show different fractionation behavior in chondritic phosphates, it may be difficult to use REE as stand-ins for Pu in 244Pu chronology.

Original languageEnglish
Pages (from-to)433-445
Number of pages13
JournalEarth and Planetary Science Letters
Volume63
Issue number3
DOIs
Publication statusPublished - 1983 Jun
Externally publishedYes

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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