Editing Earth's outer core (section)

=== Implications for Earth's accretion and core formation history ===
Tighter constraints on the concentrations of light elements in Earth's outer core would provide a better understanding of [[accretion (astrophysics)|Earth's accretion]] and [[internal structure of Earth|core formation]] history.<ref name=":0" /><ref name=":8" /><ref name=":9">{{Cite journal |last1=Rubie |first1=D. C. |last2=Jacobson |first2=S. A. |last3=Morbidelli |first3=A. |last4=O’Brien |first4=D. P. |last5=Young |first5=E. D. |last6=de Vries |first6=J. |last7=Nimmo |first7=F. |last8=Palme |first8=H. |last9=Frost |first9=D. J.| author9-link=Daniel Frost (earth scientist) |date=2015-03-01 |title=Accretion and differentiation of the terrestrial planets with implications for the compositions of early-formed Solar System bodies and accretion of water |url=https://www.sciencedirect.com/science/article/pii/S0019103514005545 |journal=Icarus |language=en |volume=248 |pages=89–108 |doi=10.1016/j.icarus.2014.10.015 |arxiv=1410.3509 |bibcode=2015Icar..248...89R |s2cid=37592339 |issn=0019-1035}}</ref>

==== Consequences for Earth's accretion ====
Models of Earth's accretion could be better tested if we had better constraints on light element [[concentration]]s in Earth's outer core.<ref name=":0" /><ref name=":9" /> For example, accretionary models based on core-mantle element partitioning tend to support proto-Earths constructed from reduced, condensed, and volatile-free material,<ref name=":0" /><ref name=":8" /><ref name=":9" /> despite the possibility that [[redox|oxidized]] material from the outer [[Solar System]] was accreted towards the conclusion of [[accretion (astrophysics)|Earth's accretion]].<ref name=":0" /><ref name=":8" /> If we could better constrain the concentrations of [[hydrogen]], [[oxygen]], and [[silicon]] in Earth's outer core, models of Earth's accretion that match these concentrations would presumably better constrain Earth’s formation.<ref name=":0" />

==== Consequences for Earth's core formation ====
[[File:Differentiation_white.png|alt=A diagram of Earth's differentiation. The diagram displays Earth's different layers and how dense materials move towards Earth's core.|thumb|A diagram of Earth's differentiation. The light elements sulfur, silicon, oxygen, carbon, and hydrogen may constitute part of the outer core due to their abundance and ability to partition into liquid iron under certain conditions.]]

The depletion of [[Goldschmidt classification#Siderophile elements|siderophile elements]] in [[Earth's mantle]] compared to chondritic meteorites is attributed to metal-silicate reactions during formation of Earth's core.<ref name=":11">{{Cite journal |last1=Badro |first1=James |last2=Brodholt |first2=John P. |last3=Piet |first3=Hélène |last4=Siebert |first4=Julien |last5=Ryerson |first5=Frederick J. |date=2015-10-06 |title=Core formation and core composition from coupled geochemical and geophysical constraints |journal=Proceedings of the National Academy of Sciences |language=en |volume=112 |issue=40 |pages=12310–12314 |doi=10.1073/pnas.1505672112 |issn=0027-8424 |pmc=4603515 |pmid=26392555|bibcode=2015PNAS..11212310B |doi-access=free }}</ref> These reactions are dependent on [[oxygen]], [[silicon]], and [[sulfur]],<ref name=":0" /><ref name=":10">{{Cite journal |last1=Fischer |first1=Rebecca A. |last2=Nakajima |first2=Yoichi |last3=Campbell |first3=Andrew J. |last4=Frost |first4=Daniel J.|author4-link=Daniel Frost (earth scientist) |last5=Harries |first5=Dennis |last6=Langenhorst |first6=Falko |last7=Miyajima |first7=Nobuyoshi |last8=Pollok |first8=Kilian |last9=Rubie |first9=David C. |date=2015-10-15 |title=High pressure metal–silicate partitioning of Ni, Co, V, Cr, Si, and O |journal=Geochimica et Cosmochimica Acta |language=en |volume=167 |pages=177–194 |doi=10.1016/j.gca.2015.06.026 |bibcode=2015GeCoA.167..177F |issn=0016-7037|doi-access=free }}</ref><ref name=":11" /> so better constraints on [[Concentration|concentrations]] of these elements in Earth's outer core will help elucidate the conditions of formation of [[Earth's core]].<ref name=":0" /><ref name=":9" /><ref name=":10" /><ref name=":11" /><ref>{{Cite journal |last1=Wade |first1=J. |last2=Wood |first2=B. J. |date=2005-07-30 |title=Core formation and the oxidation state of the Earth |url=https://www.sciencedirect.com/science/article/pii/S0012821X05003286 |journal=Earth and Planetary Science Letters |language=en |volume=236 |issue=1 |pages=78–95 |doi=10.1016/j.epsl.2005.05.017 |bibcode=2005E&PSL.236...78W |issn=0012-821X|url-access=subscription }}</ref>

In another example, the possible presence of [[hydrogen]] in Earth's outer core suggests that the [[Accretion (astrophysics)|accretion]] of Earth’s [[water]]<ref name=":0" /><ref>{{Cite journal |last1=Sato |first1=Takao |last2=Okuzumi |first2=Satoshi |last3=Ida |first3=Shigeru |date=2016-05-01 |title=On the water delivery to terrestrial embryos by ice pebble accretion |url=https://www.aanda.org/articles/aa/abs/2016/05/aa27069-15/aa27069-15.html |journal=Astronomy & Astrophysics |language=en |volume=589 |pages=A15 |doi=10.1051/0004-6361/201527069 |arxiv=1512.02414 |bibcode=2016A&A...589A..15S |s2cid=55107839 |issn=0004-6361}}</ref><ref>{{Cite journal |last1=Raymond |first1=Sean N. |last2=Quinn |first2=Thomas |last3=Lunine |first3=Jonathan I. |date=2007-02-01 |title=High-Resolution Simulations of The Final Assembly of Earth-Like Planets. 2. Water Delivery And Planetary Habitability |url=https://www.liebertpub.com/doi/10.1089/ast.2006.06-0126 |journal=Astrobiology |volume=7 |issue=1 |pages=66–84 |doi=10.1089/ast.2006.06-0126 |pmid=17407404 |arxiv=astro-ph/0510285 |bibcode=2007AsBio...7...66R |s2cid=10257401 |issn=1531-1074}}</ref> was not limited to the final stages of [[Accretion (astrophysics)|Earth's accretion]]<ref name=":9" /> and that [[water]] may have been absorbed into core-forming metals through a hydrous [[magma ocean]].<ref name=":0" /><ref>{{Cite journal |last1=Tagawa |first1=Shoh |last2=Sakamoto |first2=Naoya |last3=Hirose |first3=Kei |last4=Yokoo |first4=Shunpei |last5=Hernlund |first5=John |last6=Ohishi |first6=Yasuo |last7=Yurimoto |first7=Hisayoshi |date=2021-05-11 |title=Experimental evidence for hydrogen incorporation into Earth's core |journal=Nature Communications |language=en |volume=12 |issue=1 |pages=2588 |doi=10.1038/s41467-021-22035-0 |issn=2041-1723 |pmc=8113257 |pmid=33976113|bibcode=2021NatCo..12.2588T }}</ref>