Sr-rich apatite from the Dangzishan leucitite-ijolite xenoliths (Heilongjiang Province)

Mineralogy and mantle-fluid metasomatism

Wen Lan Zhang, Ji An Shao, Ru Cheng Wang, Xi Sheng Xu, Xu Dong Che, Yue Heng Yang

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Abundant apatite grains with elevated SrO content were found in leucitite-ijolite xenoliths in the Dangzi Mountain, Heilongjiang Province. Morphological and mineralogical associations, and compositional analysis of the Sr-rich apatite, were carried out using an electron microprobe. Two principal types of apatite were distinguished. One type occurs as short-prismatic crystals with Sr-rich rims, while another type with acicular or finely columnar shapes constitutes Sr-rich apatite element maps and systematic quantitative analysis of apatite revealed great variations in SrO content (0.42%-26.79%). The calculated structural formula of the measured Sr-rich apatite is: (Ca3.15-4.963Sr0.019-1.510Ba0.00-0.030Na0.006-0.108REE0.106-0.153) (P2.84-3.028Si0.009-0.094)O12(F0.675-1.079, Cl0.000-0.256, OH0.084-0.297). Mineralogical textures of apatite implied a replacement mechanism for the Sr-rich apatite. Sr-rich rims of apatite are suggested to have formed after metasomatism (isomorphic replacement) of early fluorapatite in a Sr-, light rare-earth elements (LREE), lithophile light elements (LILE)- and volatile-rich residual melt during late magmatism. However, the acicular apatite probably directly crystallized from a Sr-rich residual melt. The Sr-Nd isotopic composition of the apatite was distinctive from that of leucitite-ijolite and its host rock. These differences, combined with mineralogical features of apatite, imply that Sr-LREE-LILE-volatile-rich components in the residual melt were derived from deep in the asthenosphere, and subsequently were enriched at a late stage in magma evolution.

Original languageEnglish
Pages (from-to)53-63
Number of pages11
JournalChinese Science Bulletin
Volume56
Issue number1
DOIs
Publication statusPublished - Jan 2011
Externally publishedYes

Keywords

  • Dangzi Mountain
  • Depleted-mantle fluids
  • Heilongjiang Province
  • Isomorphic replacement
  • Leucitite-ijolite xenolith
  • Sr-rich apatite

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