Kilometer-scale structure on the core-mantle boundary at the source of the Hawaiian mantle plume

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cam.issuedOnline2022-05-19
dc.contributor.authorLi, Zhi
dc.contributor.authorLeng, Kuangdai
dc.contributor.authorJenkins, Jennifer
dc.contributor.authorCottaar, Sanne
dc.contributor.orcidLi, Zhi [0000-0001-5657-655X]
dc.date.accessioned2022-05-19T15:00:40Z
dc.date.available2022-05-19T15:00:40Z
dc.date.issued2022-05-19
dc.date.submitted2021-11-15
dc.date.updated2022-05-19T15:00:39Z
dc.description.abstract<jats:title>Abstract</jats:title> <jats:p>The lowermost mantle right above the core-mantle boundary shows a complex and heterogeneous landscape containing multiple poorly understood seismic features visible across a wide range of length scales. The smallest, but most extreme, heterogeneities yet observed are 'Ultra-Low Velocity Zones' (ULVZ), several of which have recently been linked to the base of mantle plumes. We exploit seismic shear waves that diffract along the core-mantle boundary to provide new insight into these enigmatic structures. We demonstrate that these waves have a strong frequency-dependent sensitivity to structure at different length scales above the core-mantle boundary, similar to the dispersive characteristics of surface waves. We measure a rare core-diffracted signal refracted by a ULVZ at the base of the Hawaiian mantle plume at unprecedented high frequencies. This signal shows remarkably longer time delays compared to lower frequencies, indicating extreme internal variability within the Hawaiian ULVZ. Utilizing the latest computational advances in 3D synthetic waveform modeling, we are able to model this high frequency signal and constrain high-resolution structure on the scale of kilometers at the core-mantle boundary, for the first time. Results reveal that the lowermost part of the Hawaiian ULVZ is extremely reduced in shear wave velocity, by up to -40%. This new observation suggests a chemically distinct ULVZ with increasing iron content towards the core-mantle boundary, which has implications for Earth’s early evolutionary history and core-mantle interaction.</jats:p>
dc.identifier.doi10.17863/CAM.84725
dc.identifier.eissn2041-1723
dc.identifier.issn2041-1723
dc.identifier.others41467-022-30502-5
dc.identifier.other30502
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/337312
dc.languageen
dc.publisherNature Research
dc.publisher.urlhttp://dx.doi.org/10.1038/s41467-022-30502-5
dc.subject37 Earth Sciences
dc.subject3705 Geology
dc.subject3706 Geophysics
dc.titleKilometer-scale structure on the core-mantle boundary at the source of the Hawaiian mantle plume
dc.typeArticle
dcterms.dateAccepted2022-04-28
prism.issueIdentifier1
prism.publicationNameNature Communications
prism.volume13
pubs.funder-project-idEuropean Research Council (804071)
rioxxterms.licenseref.urihttp://creativecommons.org/licenses/by/4.0/
rioxxterms.versionVoR
rioxxterms.versionofrecord10.1038/s41467-022-30502-5
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