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Title: Insufficient Energy From MgO Exsolution to Power Early Geodynamo

Abstract

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, in this work, 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.

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [3]; ORCiD logo [3]; ORCiD logo [4]; ORCiD logo [4]; ORCiD logo [1]
  1. Carnegie Inst. of Washington, Washington, DC (United States)
  2. Carnegie Inst. of Washington, Washington, DC (United States); Smithsonian Inst., Washington, DC (United States). National Museum of Natural History
  3. Yale Univ., New Haven, CT (United States)
  4. Univ. of Chicago, IL (United States). Center for Advanced Radiation Sources (CARS)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
Carnegie Fellowship; National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division
OSTI Identifier:
1423342
Alternate Identifier(s):
OSTI ID: 1410579
Grant/Contract Number:  
[EAR-1447311; EAR-1321956; EAR-1551348; EAR-1128799; FG02-94ER14466; AC02-06CH11357; AC02‐06CH11357]
Resource Type:
Accepted Manuscript
Journal Name:
Geophysical Research Letters
Additional Journal Information:
[ Journal Volume: 44; Journal Issue: 22]; Journal ID: ISSN 0094-8276
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
ENGLISH
Subject:
58 GEOSCIENCES; high pressure; laser‐heated diamond anvil cell; core dynamo; elemental partitioning; paleomagnetism; magnetic field

Citation Formats

Du, Zhixue, Jackson, Colin, Bennett, Neil, Driscoll, Peter, Deng, Jie, Lee, Kanani K. M., Greenberg, Eran, Prakapenka, Vitali B., and Fei, Yingwei. Insufficient Energy From MgO Exsolution to Power Early Geodynamo. United States: N. p., 2017. Web. doi:10.1002/2017GL075283.
Du, Zhixue, Jackson, Colin, Bennett, Neil, Driscoll, Peter, Deng, Jie, Lee, Kanani K. M., Greenberg, Eran, Prakapenka, Vitali B., & Fei, Yingwei. Insufficient Energy From MgO Exsolution to Power Early Geodynamo. United States. doi:10.1002/2017GL075283.
Du, Zhixue, Jackson, Colin, Bennett, Neil, Driscoll, Peter, Deng, Jie, Lee, Kanani K. M., Greenberg, Eran, Prakapenka, Vitali B., and Fei, Yingwei. Mon . "Insufficient Energy From MgO Exsolution to Power Early Geodynamo". United States. doi:10.1002/2017GL075283. https://www.osti.gov/servlets/purl/1423342.
@article{osti_1423342,
title = {Insufficient Energy From MgO Exsolution to Power Early Geodynamo},
author = {Du, Zhixue and Jackson, Colin and Bennett, Neil and Driscoll, Peter and Deng, Jie and Lee, Kanani K. M. and Greenberg, Eran and Prakapenka, Vitali B. and Fei, Yingwei},
abstractNote = {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, in this work, 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.},
doi = {10.1002/2017GL075283},
journal = {Geophysical Research Letters},
number = [22],
volume = [44],
place = {United States},
year = {2017},
month = {11}
}

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