Distinct slab interfaces imaged within the mantle transition zone

Xin Wang, Qi Fu Chen, Fenglin Niu, Shengji Wei, Jieyuan Ning, Juan Li, Weijun Wang, Johannes Buchen, Lijun Liu

Research output: Contribution to journalArticlepeer-review


Oceanic lithosphere descends into Earth’s mantle at subduction zones and drives material exchange between Earth’s surface and its deep interior. The subduction process creates chemical and thermal heterogeneities in the mantle, with the strongest gradients located at the interfaces between subducted slabs and the surrounding mantle. Seismic imaging of slab interfaces is key to understanding slab compositional layering, deep-water cycling and melting, yet the existence of slab interfaces below 200 km remains unconfirmed. Here, we observe two sharp and slightly dipping seismic discontinuities within the mantle transition zone beneath the western Pacific subduction zone that coincide spatially with the upper and lower bounds of the high-velocity slab. Based on a multi-frequency receiver function waveform modelling, we found the upper discontinuity to be consistent with the Mohorovičić discontinuity of the subducted oceanic lithosphere in the mantle transition zone. The lower discontinuity could be caused by partial melting of sub-slab asthenosphere under hydrous conditions in the seaward portion of the slab. Our observations show distinct slab–mantle boundaries at depths between 410 and 660 km, deeper than previously observed, suggesting a compositionally layered slab and high water contents beneath the slab.

Original languageEnglish (US)
Pages (from-to)822-827
Number of pages6
JournalNature Geoscience
Issue number12
StatePublished - Dec 2020

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)


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