Kilometer-scale structure on the core-mantle boundary near Hawaii.
Springer Science and Business Media LLC
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Li, Z., Leng, K., Jenkins, J., & Cottaar, S. (2022). Kilometer-scale structure on the core-mantle boundary near Hawaii.. Nat Commun, 13 (1) https://doi.org/10.1038/s41467-022-30502-5
The lowermost mantle right above the core-mantle boundary is highly heterogeneous containing multiple poorly understood seismic features. The smallest but most extreme heterogeneities yet observed are 'Ultra-Low Velocity Zones' (ULVZ). We exploit seismic shear waves that diffract along the core-mantle boundary to provide new insight into these enigmatic structures. We measure a rare core-diffracted signal refracted by a ULVZ at the base of the Hawaiian mantle plume at unprecedentedly high frequencies. This signal shows remarkably longer time delays at higher compared to lower frequencies, indicating a pronounced internal variability inside the ULVZ. Utilizing the latest computational advances in 3D waveform modeling, here we show that we are able to model this high-frequency signal and constrain high-resolution ULVZ structure on the scale of kilometers, for the first time. 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.
Article, /704/2151/508, /704/2151/2809, /119, /123, article
EC | EU Framework Programme for Research and Innovation H2020 | H2020 Priority Excellent Science | H2020 European Research Council (H2020 Excellent Science - European Research Council) (No.804071-ZoomDeep)
External DOI: https://doi.org/10.1038/s41467-022-30502-5
This record's URL: https://www.repository.cam.ac.uk/handle/1810/337312