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Insufficient Energy From MgO Exsolution to Power Early Geodynamo
Author(s) -
Du Zhixue,
Jackson Colin,
Bennett Neil,
Driscoll Peter,
Deng Jie,
Lee Kanani K. M.,
Greenberg Eran,
Prakapenka Vitali B.,
Fei Yingwei
Publication year - 2017
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 - 10.1002/2017gl075283
Subject(s) - dynamo theory , geomagnetic reversal , nucleation , geology , silicate , outer core , core (optical fiber) , inner core , geophysics , dynamo , thermal , magnetic field , thermodynamics , materials science , physics , quantum mechanics , astronomy , composite material
The origin of Earth's ancient magnetic field is an outstanding problem. It has recently been proposed that exsolution of MgO from the core may provide sufficient energy to drive an early geodynamo. Here we present new experiments on Mg partitioning between iron‐rich liquids and silicate/oxide melts. Our results indicate that Mg partitioning depends strongly on the oxygen content in the iron‐rich liquid, in contrast to previous findings that it depends only on temperature. Consequently, MgO exsolution during core cooling is drastically reduced and insufficient to drive an early geodynamo alone. Using the new experimental data, our thermal model predicts inner core nucleation at ~850 Ma and a nearly constant paleointensity.