Multiple seismic reflectors in Earth's lowermost mantle
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Shang-2014-Multiple seismic ref.pdf
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1.84 MB
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Author(s)
Shang, Xuefeng
Shim, Sang-Heon
de Hoop, Maarten
van der Hilst, Robert D
Date Issued
February 2014
Journal
Proceedings of the National Academy of Sciences
Publisher
National Academy of Sciences (U.S.)
Citation
Shang, X., S.-H. Shim, M. de Hoop, and R. van der Hilst. “Multiple Seismic Reflectors in Earth’s Lowermost Mantle.” Proceedings of the National Academy of Sciences 111, no. 7 (February 3, 2014): 2442–2446.
Version
Final published version
Abstract
The modern view of Earth’s lowermost mantle considers a D″ region of enhanced (seismologically inferred) heterogeneity bounded by the core–mantle boundary and an interface some 150–300 km above it, with the latter often attributed to the postperovskite phase transition (in MgSiO[subscript 3]). Seismic exploration of Earth’s deep interior suggests, however, that this view needs modification. So-called ScS and SKKS waves, which probe the lowermost mantle from above and below, respectively, reveal multiple reflectors beneath Central America and East Asia, two areas known for subduction of oceanic plates deep into Earth’s mantle. This observation is inconsistent with expectations from a thermal response of a single isochemical postperovskite transition, but some of the newly observed structures can be explained with postperovskite transitions in differentiated slab materials. Our results imply that the lowermost mantle is more complex than hitherto thought and that interfaces and compositional heterogeneity occur beyond the D″ region sensu stricto.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1073/pnas.1312647111
