Constraints on Earth’s inner core composition inferred from measurements of the sound velocity of hcp-iron in extreme conditions

Abstract

Experimental determination of VP of hcp-Fe can show potential candidates for major light elements in Earth’s inner core.

Velocity‐Density Systematics of Fe‐5wt%Si: Constraints on Si Content in the Earth's Inner Core

“…To meaningfully compare obtained Vp and Vs with PREM, high temperature effects have to be accounted for. At a constant density of 13 g/cm 3 , the T corrections on Vp after experiments by Sakamaki et al (; on hcp‐Fe) and Sakairi et al (; on Fe‐6Si) yield Vp reductions of ∼0.09 m·s −1 ·K −1 , with almost no difference between Fe and Fe‐6Si. Alternatively, by converting the constant pressure simulations of Martorell et al () to a constant density of 13 g/cm 3 , it is possible to estimate the magnitude of anharmonic temperature effects to be ∼0.11 m·s −1 ·K −1 for Fe and Fe3.3Si, and ∼0.05 m·s −1 ·K −1 for Fe‐6.7Si.…”

Experimental constraints on the fate of H and C during planetary core-mantle differentiation. Implications for the Earth

“…It has been shown that H or C can easily be combined with iron at high pressures (HP) and high temperatures (HT) and could explain such a density deficit (e.g. Fukai, 1984 ;Badding et al, 1991 ;Yagi and Hishinuma, 1995 ;Wood et al, 1996 ;Okuchi, 1997;Saxena A C C E P T E D M A N U S C R I P T Sakamaki et al, 2009 ;Shibazaki et al, 2009Shibazaki et al, , 2011Dasgupta et al, 2009 ;Dasgupta and Hirschmann, 2010 ;Narygina et al, 2011 ;Shibazaki et al, 2012Shibazaki et al, , 2014Sakamaki et al, 2016 ;Iizuka-Oku et al, 2017 ;Dasgupta et al, 2013 ;Lord et al, 2009 ;Tsuno et al, 2018) . However, a recent study of Clesi et al (2018) showed that H is lithophile during core -mantle equilibration and it might be a very minor element in the Earth's core.…”

Chemical Reactions Between Fe and H2O up to Megabar Pressures and Implications for Water Storage in the Earth's Mantle and Core

“…Experimental and theoretical studies of FeHx suggest that such an iron hydride can satisfy the density and sound velocity of the Earth's core (Hirao et al, 2004;Mao et al, 2004;Sakamaki et al, 2016;Shibazaki et al, 2012;Tagawa et al, 2016). A primary mechanism for including hydrogen into the Earth's core might be through reaction between iron and water during core formation.…”