The Earth's corecompositionfromhighpressuredensity measurementsofliquidironalloys
Résumé
High-pressure,high-temperature in situ X-raydiffractionhasbeenmeasuredinliquidironalloys(Fe- 5 wt%Ni-12wt%SandFe-5 wt%Ni-15wt%Si)upto94GPaand3200Kinlaser-heateddiamondanvil cells. FromtheanalysisoftheX-raydiffusescatteringsignalofthemetallicliquids,wedetermined density andbulkmodulusofthetwoliquidalloys.ComparisonwithareferenceEarthmodelindicates that acorecompositioncontaining6%ofsulfurand2%ofsiliconbyweightwouldbestmatchthe geophysicaldata.Modelswith2.5%ofsulfurand4-5% ofsiliconarestillconsistentwithgeophysical constraints whereassilicononlycompositionsarenot.Theseresultssuggestonlymoderatedepletionof sulfur inthebulkEarth