Distribution of W and Mo in ordinary chondrites and implications for nebular and parent body thermal processes

Ping Kong, Mitsuru Ebihara

研究成果: Article査読

10 被引用数 (Scopus)

抄録

W and Mo abundances in the bulk metals of 10 H, 5 L and 6 LL chondrites were determined by instrumental neutron activation analysis (INAA). Partitioning of W and Mo between metal and non-metal phases was evaluated by comparing Ni-normalized W and Mo abundances in the metal phases with those in the bulk samples. It is observed that W distributions differ significantly between equilibrated ordinary chondrites (EOCs) and unequilibrated ordinary chondrites (UOCs). However, no correlation is confirmed between the W distribution and the petrographic type for EOCs. This implies that the W partitioning among mineral phases can provide a clue for estimating the metamorphic temperature intervening between EOCs and UOCs. The difference in W equilibrium temperatures was observed among H, L and LL chondrite groups and it may correspond to the difference in cooling rates and subsequently in sizes of the chondrite parent bodies; LL chondrites have the lowest equilibrium temperature and, hence, have the largest parent body, whereas H chondrites have the highest equilibrium temperature and the smallest parent body. Mo/W abundance ratios remain constant in EOC metals, but are variable in UOC metals, suggesting that the W solid equilibrium has not been achieved in UOCs. The W and Mo distributions in UOCs still preserve the characteristics of W and Mo in the nebula, which demonstrates that the chondritic metal was formed by melting highly oxidized precursors before or during the accretion of chondrite parent bodies.

本文言語English
ページ(範囲)83-93
ページ数11
ジャーナルEarth and Planetary Science Letters
137
1-4
出版ステータスPublished - 1996 1
外部発表はい

ASJC Scopus subject areas

  • 地球物理学
  • 地球化学および岩石学
  • 地球惑星科学(その他)
  • 宇宙惑星科学

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