Global observations of reflectors in the mid-mantle with implications for mantle structure and dynamics

Waszek, Lauren, Schmerr, Nicholas C., and Ballmer, Maxim D. (2018) Global observations of reflectors in the mid-mantle with implications for mantle structure and dynamics. Nature Communications, 9. 385.

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Abstract

Seismic tomography indicates that flow is commonly deflected in the mid-mantle. However, without a candidate mineral phase change, causative mechanisms remain controversial. Deflection of flow has been linked to radial changes in viscosity and/or composition, but a lack of global observations precludes comprehensive tests by seismically detectable features. Here we perform a systematic global-scale interrogation of mid-mantle seismic reflectors with lateral size 500–2000 km and depths 800–1300 km. Reflectors are detected globally with variable depth, lateral extent and seismic polarity and identify three distinct seismic domains in the mid-mantle. Near-absence of reflectors in seismically fast regions may relate to dominantly subvertical heterogeneous slab material or small impedance contrasts. Seismically slow thermochemical piles beneath the Pacific generate numerous reflections. Large reflectors at multiple depths within neutral regions possibly signify a compositional or textural transition, potentially linked to long-term slab stagnation. This variety of reflector properties indicates widespread compositional heterogeneity at mid-mantle depths.

Item ID: 65360
Item Type: Article (Research - C1)
ISSN: 2041-1723
Copyright Information: Open Access. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. © The Author(s) 2018
Funders: Australian Government (AG), National Science Foundation (NSF)
Projects and Grants: AG Discovery Early Career Research Award DE170100329, NSF EAR-1361325, NSF EAR-1135452
Date Deposited: 08 Jan 2021 00:05
FoR Codes: 37 EARTH SCIENCES > 3706 Geophysics > 370609 Seismology and seismic exploration @ 75%
37 EARTH SCIENCES > 3706 Geophysics > 370604 Geodynamics @ 25%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
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