Immiscibility of the grossular-spessartine series under a water pressure of 100 MPa

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Author(s)

    • SHOJI Tetsuya
    • Department of Geosystem Engineering, School of Engineering, The University of Tokyo
    • TSUKADA Hiroko
    • Institute of Earth Science, School of Education, Waseda University
    • MARIKO Tadashi
    • Institute of Earth Science, School of Education, Waseda University
    • KANEDA Hiroaki
    • Department of Geosystem Engineering, School of Engineering, The University of Tokyo

Abstract

Electron microprobe analysis of grossular-spessartine garnets hydrothermally synthesized from glass at 300–700°C shows that the composition is continuous above 490°C. Below this temperature there is a compositional gap between 70 and 96 mol % spessartine at 480°C and between 55 and 97 mol % at 450°C. The gap extends up to 36 mol % spessartine at 400°C and up to 30 mol % at 300°C on the grossular side, but is not clear on the spessartine side because of the fO<SUB>2</SUB> unbuffered experiments. Hydrothermal treatment of garnet-anorthite-tephroite mixture with bulk composition of Gr<SUB>33.3</SUB> Sp<SUB>66.7</SUB> shows that garnet grows above 430°C, and that no change is recognized at 400°C. These facts indicate that garnet of the grossular-spessartine series forms a complete solid solution above 490°C, and shows a certain indication that they exsolve to Ca-rich and Mn-rich garnets at lower temperatures. The additional experiments indicate that below 415°C the tie-line connecting the two garnets is replaced by the one connecting anorthite and tephroite in the system CaO–MnO–Al<SUB>2</SUB>O<SUB>3</SUB>–SiO<SUB>2</SUB>.

Journal

  • Mineralogical Journal

    Mineralogical Journal 17(7), 313-321, 1995-07-01

    Japan Association of Mineralogical Sciences

References:  9

Cited by:  2

Codes

  • NII Article ID (NAID)
    10008771242
  • NII NACSIS-CAT ID (NCID)
    AA00739590
  • Text Lang
    ENG
  • Article Type
    Journal Article
  • ISSN
    05442540
  • Data Source
    CJP  CJPref  J-STAGE 
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