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Sound Velocity of MgSiO 3 Majorite Garnet up to 18 GPa and 2000 K
Author(s) -
Zhou Chunyin,
Gréaux Steeve,
Liu Zhaodong,
Higo Yuji,
Arimoto Takeshi,
Irifune Tetsuo
Publication year - 2021
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 - 10.1029/2021gl093499
Subject(s) - geology , mineralogy , transition zone , silicate , mantle (geology) , seismic velocity , geochemistry , seismology , physics , astronomy
MgSiO 3 majorite is the most significant endmember of the Al‐deficient majorite garnets that form at depths higher than ∼400 km, in the mantle transition zone (MTZ). Here, we report elastic wave velocity measurements on polycrystalline MgSiO 3 majorite samples, up to 18.4 GPa and 2000 K by ultrasonic interferometry techniques combined with in situ X‐ray diffraction measurements in a multianvil apparatus. Our data show MgSiO 3 majorite has the lowest elastic moduli among silicate garnet endmembers, under the pressure and temperature conditions of the MTZ. These new data combined with those of other garnet endmembers allowed to estimate V P and V S of majorite with compositions relevant to the MTZ. The results suggest that variation of MgSiO 3 component in garnet may play a role for interpreting seismic gradients atop the 410‐km discontinuity while below ∼520 km, the velocity contrasts hold too low values to explain the discrepancy between mineral physics data and seismological observations.