A nonmagnetic differentiated early planetary body

Benjamin P. Weiss, Huapei Wang, Thomas Sharp, Jérôme Gattacceca, David L. Shuster, Brynna Downey, Jinping Hu, Roger R. Fu, Aaron T. Kuan, Clément Suavet, Anthony J. Irving, Jun Wang, Jiajun Wang

    Research output: Contribution to journalArticle

    4 Citations (Scopus)

    Abstract

    Paleomagnetic studies of meteorites have shown that the solar nebula was likely magnetized and that many early planetary bodies generated dynamo magnetic fields in their advecting metallic cores. The surface fields on these bodies were recorded by a diversity of chondrites and achondrites, ranging in intensity from several μT to several hundred μT. In fact, an achondrite parent body without evidence for paleomagnetic fields has yet to be confidently identified, hinting that early solar system field generation and the dynamo process in particular may have been common. Here we present paleomagnetic measurements of the ungrouped achondrite NWA 7325 indicating that it last cooled in a near-zero field (<∼1.7 μT), estimated to have occurred at 4563.09±0.26 million years ago (Ma) from Al–Mg chronometry. Because NWA 7325 is highly depleted in siderophile elements, its parent body nevertheless underwent large-scale metal-silicate differentiation and likely formed a metallic core. This makes NWA 7325 the first recognized example of an essentially unmagnetized igneous rock from a differentiated early solar system body. These results indicate that all magnetic fields, including those from any core dynamo on the NWA 7325 parent body, the solar nebula, young Sun, and solar wind, were <1.7 μT at the location of NWA 7325 at 4563 Ma. This supports a recent conclusion that the solar nebula had dissipated by ∼4 million years after solar system formation. NWA 7325 also serves as an experimental control that gives greater confidence in the positive identification of remanent magnetization in other achondrites.

    Original languageEnglish (US)
    Pages (from-to)119-132
    Number of pages14
    JournalEarth and Planetary Science Letters
    Volume468
    DOIs
    StatePublished - Jun 15 2017

    Fingerprint

    achondrite
    Solar system
    achondrites
    parent body
    solar system
    solar nebula
    Igneous rocks
    Magnetic fields
    Meteorites
    Silicates
    Solar wind
    magnetic field
    siderophile element
    Sun
    Magnetization
    remanent magnetization
    Metals
    siderophile elements
    chondrite
    meteorite

    Keywords

    • differentiation
    • dynamo
    • meteorites
    • paleomagnetism
    • planetesimals

    ASJC Scopus subject areas

    • Geophysics
    • Geochemistry and Petrology
    • Earth and Planetary Sciences (miscellaneous)
    • Space and Planetary Science

    Cite this

    Weiss, B. P., Wang, H., Sharp, T., Gattacceca, J., Shuster, D. L., Downey, B., ... Wang, J. (2017). A nonmagnetic differentiated early planetary body. Earth and Planetary Science Letters, 468, 119-132. https://doi.org/10.1016/j.epsl.2017.03.026

    A nonmagnetic differentiated early planetary body. / Weiss, Benjamin P.; Wang, Huapei; Sharp, Thomas; Gattacceca, Jérôme; Shuster, David L.; Downey, Brynna; Hu, Jinping; Fu, Roger R.; Kuan, Aaron T.; Suavet, Clément; Irving, Anthony J.; Wang, Jun; Wang, Jiajun.

    In: Earth and Planetary Science Letters, Vol. 468, 15.06.2017, p. 119-132.

    Research output: Contribution to journalArticle

    Weiss, BP, Wang, H, Sharp, T, Gattacceca, J, Shuster, DL, Downey, B, Hu, J, Fu, RR, Kuan, AT, Suavet, C, Irving, AJ, Wang, J & Wang, J 2017, 'A nonmagnetic differentiated early planetary body' Earth and Planetary Science Letters, vol. 468, pp. 119-132. https://doi.org/10.1016/j.epsl.2017.03.026
    Weiss, Benjamin P. ; Wang, Huapei ; Sharp, Thomas ; Gattacceca, Jérôme ; Shuster, David L. ; Downey, Brynna ; Hu, Jinping ; Fu, Roger R. ; Kuan, Aaron T. ; Suavet, Clément ; Irving, Anthony J. ; Wang, Jun ; Wang, Jiajun. / A nonmagnetic differentiated early planetary body. In: Earth and Planetary Science Letters. 2017 ; Vol. 468. pp. 119-132.
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