X-ray Raman scattering study of MgSiO 3 glass at high pressure: Implication for triclustered MgSiO 3 melt in Earth's mantle

• DOI: 10.1073/pnas.0802667105
• Publication Date: 2008-06-06T01:06:31Z
• Authors: Sung Keun Lee; Jung-Fu Lin; Yong Q. Cai; Nozomu Hiraoka; Peter J. Eng; Takuo Okuchi; Ho-kwang Mao; Yue Meng; Michael Y. Hu; Paul Chow; Jinfu Shu; Baosheng Li; Hiroshi Fukui; Bum Han Lee; Hyun Na Kim; Choong-Shik Yoo
• Keywords: Supercooling

Silicate melts at the top of transition zone and core-mantle boundary have significant influences on dynamics properties Earth's interior. MgSiO3-rich silicate were among primary components magma ocean thus played essential roles in chemical differentiation early Earth. Diverse macroscopic interior, such as density, viscosity, crystal-melt partitioning, depend their electronic short-range local structures high pressures temperatures. Despite many geophysical geodynamic problems, little is known about nature under conditions including densification mechanisms atomistic origins pressures. Here, we probed MgSiO3 glass (as a precursor to Mg-silicate melts), using high-pressure x-ray Raman spectroscopy up 39 GPa, which oxygen K-edge features suggest formation tricluster oxygens (oxygen coordinated with three Si frameworks; 3O) between 12 20 GPa. Our results indicate that melt likely be accompanied triculster, addition reduction nonbridging oxygens. The pressure-induced increase fraction triclusters >20 GPa would result enhanced reduced element diffusivity toward deeper part lower mantle.