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Hydrous modified spinel, Mg 1.75 SiH 0.5 O 4 : A new water reservoir in the mantle transition region
Author(s) -
Inoue Toru,
Yurimoto Hisayoshi,
Kudoh Yasuhiro
Publication year - 1995
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/94gl02965
Subject(s) - spinel , mantle (geology) , transition zone , analytical chemistry (journal) , mineralogy , microprobe , geology , crystallography , materials science , geochemistry , chemistry , environmental chemistry , paleontology
The water content in modified spinel, synthesized at 15.5 GPa under hydrous conditions, has been measured by means of secondary ion mass spectrometry (SIMSrpar;. We found that the modified spinel crystals contain up to 3.1±0.4 wt % H 2 O, which is consistent with the amounts estimated from the deficits in the oxide totals of the microprobe analysis. X‐ray diffraction analyses for a single crystal showed that the sample containing 2.5±0.3 wt % H 2 O is of the modified spinel structure with the lattice parameters a=5.663(1), b=11.546(2), c=8.247(4)Å and V=539.2(5)ų. The present results suggest that a considerable amount of H 2 O may exist as hydrous modified spinel in the mantle transition zone, which could have important implications for the constitution and dynamics of the mantle.