Origin of kamacite, schreibersite, and perryite in metal-sulfide nodules of the enstatite chondrite Sahara 97072 (EH3)

Stephen W. Lehner, P R Buseck, William F. McDonough

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

Perryite [(Fe,Ni)x(Si,P)y], schreibersite [(Fe,Ni)3P], and kamacite (αFeNi) are constituent minerals of the metal-sulfide nodules in the Sahara 97072 (EH3) enstatite chondrite meteorite. We have measured concentrations of Ni, Cu, Ga, Au, Ir, Ru, and Pd in these minerals with laser ablation, inductively coupled plasma mass spectrometry (ICP-MS). We also measured their Fe, Ni, P, Si, and Co concentrations with electron microprobe. In kamacite, ratios of Ru/Ir, Pd/Ir, and Pd/Ru cluster around their respective CI values and all elements analyzed plot near the intersection of the equilibrium condensation trajectory versus Ni and the respective CI ratios. In schreibersite, the Pd/Ru ratio is near the CI value and perryite contains significant Cu, Ga, and Pd. We propose that schreibersite and perryite formed separately near the condensation temperatures of P and Si in a reduced gas and were incorporated into Fe-Ni alloy. Upon further cooling, sulfidation of Fe in kamacite resulted in the formation of additional perryite at the sulfide interface. Still later, transient heating re-melted this perryite near the Fe-FeS eutectic temperature during partial melting of the metal-sulfide nodules. The metal-sulfide nodules are pre-accretionary objects that retain CI ratios of most siderophile elements, although they have experienced transient heating events.

Original languageEnglish (US)
Pages (from-to)289-303
Number of pages15
JournalMeteoritics and Planetary Science
Volume45
Issue number2
DOIs
StatePublished - Feb 1 2010

    Fingerprint

ASJC Scopus subject areas

  • Geophysics
  • Space and Planetary Science

Cite this