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Scattered wave imaging of the oceanic plate in Cascadia

Scattered wave imaging of the oceanic plate in Cascadia
Scattered wave imaging of the oceanic plate in Cascadia
Fifty years after plate tectonic theory was developed, the defining mechanism of the plate is still widely debated. The relatively short, simple history of young ocean lithosphere makes it an ideal place to determine the property that defines a plate, yet the remoteness and harshness of the seafloor have made precise imaging challenging. We use S-to-P receiver functions to image discontinuities beneath newly formed lithosphere at the Juan de Fuca and Gorda Ridges. We image a strong negative discontinuity at the base of the plate increasing from 20 to 45 km depth beneath the 0- to 10-million-year-old seafloor and a positive discontinuity at the onset of melting at 90 to 130 km depth. Comparison with geodynamic models and experimental constraints indicates that the observed discontinuities cannot easily be reconciled with subsolidus mechanisms. Instead, partial melt may be required, which would decrease mantle viscosity and define the young oceanic plate.
2375-2548
Rychert, Catherine
70cf1e3a-58ea-455a-918a-1d570c5e53c5
Harmon, Nicholas
10d11a16-b8b0-4132-9354-652e72d8e830
Tharimena, Saikiran
9e95dff0-7044-43d4-ac5e-51e72468b719
Rychert, Catherine
70cf1e3a-58ea-455a-918a-1d570c5e53c5
Harmon, Nicholas
10d11a16-b8b0-4132-9354-652e72d8e830
Tharimena, Saikiran
9e95dff0-7044-43d4-ac5e-51e72468b719

Rychert, Catherine, Harmon, Nicholas and Tharimena, Saikiran (2018) Scattered wave imaging of the oceanic plate in Cascadia. Science Advances, 4 (2), [eaao1908]. (doi:10.1126/sciadv.aao1908).

Record type: Article

Abstract

Fifty years after plate tectonic theory was developed, the defining mechanism of the plate is still widely debated. The relatively short, simple history of young ocean lithosphere makes it an ideal place to determine the property that defines a plate, yet the remoteness and harshness of the seafloor have made precise imaging challenging. We use S-to-P receiver functions to image discontinuities beneath newly formed lithosphere at the Juan de Fuca and Gorda Ridges. We image a strong negative discontinuity at the base of the plate increasing from 20 to 45 km depth beneath the 0- to 10-million-year-old seafloor and a positive discontinuity at the onset of melting at 90 to 130 km depth. Comparison with geodynamic models and experimental constraints indicates that the observed discontinuities cannot easily be reconciled with subsolidus mechanisms. Instead, partial melt may be required, which would decrease mantle viscosity and define the young oceanic plate.

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Accepted/In Press date: 11 January 2018
e-pub ahead of print date: 14 February 2018
Published date: February 2018

Identifiers

Local EPrints ID: 417907
URI: http://eprints.soton.ac.uk/id/eprint/417907
ISSN: 2375-2548
PURE UUID: 0e849b5b-659e-472b-9e34-c8a3c97a1ca0
ORCID for Nicholas Harmon: ORCID iD orcid.org/0000-0002-0731-768X
ORCID for Saikiran Tharimena: ORCID iD orcid.org/0000-0002-1841-1911

Catalogue record

Date deposited: 16 Feb 2018 17:30
Last modified: 07 Oct 2020 02:14

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