cam.issuedOnline	2022-05-19
dc.contributor.author	Li, Zhi
dc.contributor.author	Leng, Kuangdai
dc.contributor.author	Jenkins, Jennifer
dc.contributor.author	Cottaar, Sanne
dc.contributor.orcid	Li, Zhi [0000-0001-5657-655X]
dc.date.accessioned	2022-05-19T15:00:40Z
dc.date.available	2022-05-19T15:00:40Z
dc.date.issued	2022-05-19
dc.date.submitted	2021-11-15
dc.date.updated	2022-05-19T15:00:39Z
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.doi	10.17863/CAM.84725
dc.identifier.eissn	2041-1723
dc.identifier.issn	2041-1723
dc.identifier.other	s41467-022-30502-5
dc.identifier.other	30502
dc.identifier.uri	https://www.repository.cam.ac.uk/handle/1810/337312
dc.language	en
dc.language.iso	eng
dc.publisher	Nature Research
dc.publisher.url	http://dx.doi.org/10.1038/s41467-022-30502-5
dc.subject	37 Earth Sciences
dc.subject	3705 Geology
dc.subject	3706 Geophysics
dc.title	Kilometer-scale structure on the core-mantle boundary at the source of the Hawaiian mantle plume
dc.type	Article
dcterms.dateAccepted	2022-04-28
prism.issueIdentifier	1
prism.publicationName	Nature Communications
prism.volume	13
pubs.funder-project-id	European Research Council (804071)
rioxxterms.licenseref.uri	http://creativecommons.org/licenses/by/4.0/
rioxxterms.version	VoR
rioxxterms.versionofrecord	10.1038/s41467-022-30502-5

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

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