Reevaluation of formation of metal nodules in ordinary chondrites

Ping Kong, Mitsuru Ebihara, Xiande Xie

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Compositions of four metal nodules from two ordinary chondrites, WIS91627 (H3.7) and Jilin (H5), were determined by instrumental and radiochemical neutron activation analyses. Compared with bulk metal fractions, the metal nodules are characterized by strong and variable depletion of the refractory siderophile elements Re, Os, Ir, Ru, Pt and Rh but normal W and Mo, some fractionation of Co from Ni, and low Cu concentrations. These characteristics are difficult to explain by shock-induced vaporization followed by fractional condensation, a mechanism suggested by Widom et al. (1986). We propose formation of metal nodules during metamorphism in the parent body. Refractory siderophile elements, such as Ir, Os, Rh, etc., are partly locked up in noble metal nuggets and cannot participate in kamacite formation. The occurrence of metal nodules in both equilibrated and unequilibrated ordinary chondrites suggests that diffusion along grain boundaries was important in the development of kamacite and taenite in ordinary chondrites.

Original languageEnglish
Pages (from-to)993-998
Number of pages6
JournalMeteoritics and Planetary Science
Volume33
Issue number5
DOIs
Publication statusPublished - 1998 Sep
Externally publishedYes

Keywords

  • Chondrite
  • Meteorite

ASJC Scopus subject areas

  • Geophysics
  • Space and Planetary Science

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