10:45 AM - 11:00 AM
[SIT19-07] Elasticity of superhydrous phase B at the mantle temperature and pressure: Implications for 800-km discontinuity and water flow into lower mantle
Keywords:elasticity at high pressure and temperature, hydrous phase, first-principle calculations
We investigated the elasticity of ShyB at high temperature and pressure using first principle calculations [Yang et al., 2017]. Our first-principles calculations indicate that the decomposition of ShyB will cause the Vp, Vs, and density increase by 7.5%, 15.0% and 12%, respectively. Thus the decomposition of a small amount of ShyB sufficiently generates 800-km the discontinuity and may be related to the seismic discontinuity at the depth of ~ 800 km in Western-Pacific Subduction Zones [Liu et al., 2016; Porritt and Yoshioka, 2016]. The water released from the decomposition of ShyB promotes the partial melt, which can further explain the low-velocity anomalies just above 800-km discontinuity. The result supports strongly the appearance of ShyB at the lower mantle and has many significant implications on deep water cycle.
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