Chemical characteristics of the lherzolitic shergottite Yamato 000097: magmatism on Mars inferred from the chemical compositions of shergottites

Naoki Shirai, Mitsuru Ebihara

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Abstract

As a part of a consortium study, we analyzed the Martian meteorite Yamato (Y) 000097 by prompt gamma-ray analysis, instrumental neutron activation analysis, and instrumental photon activation analysis. For comparison, we also analyzed Allan Hills (ALH) 77005 using the same methods. The data confirm that Y000097 belongs to lherzolitic shergottites in terms of chemical composition. Although there exist slight differences in elemental abundances among lherzolitic shergottites due to differences in the modal abundances of constituent minerals, they have essentially the same chemical compositions, suggesting they are genetically related and experienced similar formation histories. Zr/Hf ratios obtained for Y000097 and ALH 77005 are subchondritic, consistent with values reported for other lherzolitic shergottites and olivine-phyric shergottites. Such fractionation can be explained by invoking clinopyroxene, ilmenite, or majorite in the petrogenesis of the shergottites' source material. CI-normalized Hf/Sm ratios obtained for Y000097 and ALH 77005 are 1.52 and 1.37, respectively, consistent with superchondritic Hf/Sm ratios reported for shergottites. Based on experimentally derived partition coefficients, majorite is the best candidate mineral for the fractionation of Hf and Sm in shergottites.

Original languageEnglish
Pages (from-to)117-133
Number of pages17
JournalPolar Science
Volume3
Issue number2
DOIs
Publication statusPublished - 2009 Sep 1
Externally publishedYes

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Keywords

  • Chemical composition
  • Lherzolitic shergottites
  • Magmatism
  • Y 000097

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)
  • Aquatic Science
  • Ecology, Evolution, Behavior and Systematics
  • Ecology

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