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The symmetry of garnets on the pyrope (Mg 3 Al 2 Si 3 O 12 )‐majorite (MgSiO 3 ) join
Author(s) -
Parise John B.,
Wang Yanbin,
Gwanmesia Gabriel D.,
Zhang Jianzhong,
Sinelnikov Yegor,
Chmielowski Josef,
Weidner Donald J.,
Liebermann Robert C.
Publication year - 1996
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 - 10.1029/96gl03613
Subject(s) - pyrope , tetragonal crystal system , materials science , mineralogy , solid solution , phase (matter) , geology , crystallography , crystal structure , chemistry , metallurgy , organic chemistry
Garnets with compositions between majorite and pyrope, Mj 38 , Mj 48 , Mj 75 and Mj 79 were synthesized at high pressures and temperatures in a 2000‐ton uniaxial split‐sphere apparatus (USSA‐2000) and investigated using high resolution synchrotron X‐ray powder diffraction and transmission electron microscopy. The results from both techniques are consistent with the tetragonal field for these garnets extending to a majorite composition just below Mj 75 . The cubic‐tetragonal structural phase transition in garnet along the majorite‐pyrope join is sensitive to both composition and temperature and is expected to result in anomalous behavior in elastic shear moduli. This phase transition may occur in the transition zone of the earth's mantle and will have important effects on the elastic and rheological properties of this region where these garnets are stable phases.