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Low Melting Temperature of Anhydrous Mantle Materials at the Core‐Mantle Boundary
Author(s) -
Kim Taehyun,
Ko Byeongkwan,
Greenberg Eran,
Prakapenka Vitali,
Shim SangHeon,
Lee Yongjae
Publication year - 2020
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 - 10.1029/2020gl089345
Subject(s) - solidus , mantle (geology) , anhydrous , core–mantle boundary , eutectic system , geology , mineralogy , partial melting , analytical chemistry (journal) , thermodynamics , materials science , geophysics , chemistry , physics , metallurgy , microstructure , organic chemistry , alloy , chromatography
One of the central challenges in accurately estimating the mantle melting temperature is the sensitivity of the probe for detecting a small amount of melt at the solidus. To address this, we used a multichannel collimator to enhance the diffuse X‐ray scattering from a small amount of melt and probed an eutectic pyrolitic composition to increase the amount of melt at the solidus. Our in situ detection of diffuse scattering from the pyrolitic melt determined an anhydrous melting temperature of 3,302 ± 100 K at 119 ± 6 GPa and 3,430 ± 130 K at the core‐mantle boundary (CMB) conditions, as the upper bound temperature. Our CMB temperature is approximately 700 K lower than the previous estimates, implying much faster secular cooling and higher concentrations of S, C, O, and/or H in the region, and nonlinear, advocating the basal magma ocean hypothesis.