He and Ar isotopes in mantle megacryst minerals from Nushan and Yingfengling in Southeast China

Shijin Xu*, Zhong Fang, T. Matsumoto, J. Matsuda, M. Yasuda, Jinhai Yu, Rucheng Wang, Wenzhong Liu

*Corresponding author for this work

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

He and Ar isotopic compositions of megacrystal minerals from mantle xenoliths were measured by the technique of vacuum crushing extraction. The used samples were clinopyroxene, garnet and ilmenite in Cenozoic alkaline basalts, which were from Nushan in Anhui Province and Yingfengling in Guangdong Province, respectively, and represented materials from the upper mantle in the continental margin of SE China. The results show 3He/4He ratios of 7.99 Ra to 8.58 Ra, consistent with the characteristic ratios of the MORB-type mantle. 40Ar/39Ar ratios vary from 313 to 909, suggesting a binary mixing between the MORB-type mantle and air argons. This may reflect the incorporation of the air argon absorbed in oceanic sediments into the mantle beneath the continental margin by subduction of oceanic plate. This study presents the first report that ilmenite megacrysts contain abundant fluid inclusions and noble gases in the mantle xenoliths.

Original languageEnglish
Pages (from-to)1624-1630
Number of pages7
JournalChinese Science Bulletin
Volume48
Issue number15
DOIs
Publication statusPublished - 2003
Externally publishedYes

Keywords

  • Depleted mantle
  • He and Ar isotope
  • Mantle contamination
  • Mantle mineral

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