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Elasticity of single‐crystal superhydrous phase B at simultaneous high pressure‐temperature conditions
Author(s) -
Li Xinyang,
Mao Zhu,
Sun Ningyu,
Liao Yifan,
Zhai Shuangmeng,
Wang Yi,
Ni Huaiwei,
Wang Jingyun,
Tkachev Sergey N.,
Lin JungFu
Publication year - 2016
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 - 10.1002/2016gl070027
Subject(s) - peridotite , geology , anisotropy , mantle (geology) , slab , elasticity (physics) , brillouin scattering , transition zone , subduction , mineralogy , geophysics , seismology , materials science , optics , tectonics , physics , composite material , optical fiber
We investigated the combined effect of pressure and temperature on the elasticity of single‐crystal superhydrous phase B (Shy‐B) using Brillouin scattering and X‐ray diffraction up to 12 GPa and 700 K. Using the obtained elasticity, we modeled the anisotropy of Shy‐B along slab geotherms, showing that Shy‐B has a low anisotropy and cannot be the major cause of the observed anisotropy in the region. Modeled velocities of Shy‐B show that Shy‐B will be shown as positive velocity anomalies at the bottom transition zone. Once Shy‐B is transported to the topmost lower mantle, it will exhibit a seismic signature of lower velocities than topmost lower mantle. We speculate that an accumulation of hydrous phases, such as Shy‐B, at the topmost lower mantle with a weight percentage of ~17–26% in the peridotite layer as subduction progresses could help explain the observed 2–3% low shear velocity anomalies in the region.