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Shock compression of Fe‐Ni‐Si system to 280 GPa: Implications for the composition of the Earth's outer core
Author(s) -
Zhang Youjun,
Sekine Toshimori,
He Hongliang,
Yu Yin,
Liu Fusheng,
Zhang Mingjian
Publication year - 2014
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 - 10.1002/2014gl060670
Subject(s) - earth (classical element) , inner core , materials science , outer core , shock (circulatory) , core (optical fiber) , silicon , compression (physics) , mineralogy , analytical chemistry (journal) , thermodynamics , geology , physics , metallurgy , chemistry , composite material , medicine , chromatography , mathematical physics
The shock Hugoniot of an Fe‐9 wt %Ni‐10 wt %Si system as a model of the Earth's core has been measured up to ~280 GPa using a two‐stage light‐gas gun. The samples had an average density of 6.853 (±0.036) g/cm 3 . The relationship between shock velocity ( U s ) and particle velocity ( u p ) can be described by U s (km/s) = 3.95 (±0.15) + 1.53 (±0.05) u p (km/s). The calculated Hugoniot temperatures and the melting curve indicate that the model composition melts above a shock pressure of ~168 GPa, which is significantly lower than the shock‐melting pressure of iron (~225 GPa). A comparison of the pressure‐density ( P‐ρ ) profiles between the model composition and the preliminary reference Earth model gives a silicon content close to 10 wt %, necessary to compensate the density deficit in the Earth's outer core from seismological observations, if silicon is present as a major light element in the Fe‐Ni core system.