The University of Southampton
University of Southampton Institutional Repository

A dynamic lithosphere–asthenosphere boundary near the equatorial Mid-Atlantic Ridge

A dynamic lithosphere–asthenosphere boundary near the equatorial Mid-Atlantic Ridge
A dynamic lithosphere–asthenosphere boundary near the equatorial Mid-Atlantic Ridge
In plate tectonic theory a weak asthenosphere is required to facilitate the motions of the rigid plates. Partial melt could weaken the mantle, in turn impacting convection, but to date the existence of persistent melt has remained controversial. A wide range of scenarios has been reported in terms of the location, amount and pathways of melt. Here we use data collected by 39 ocean bottom seismometers deployed near the equatorial Mid-Atlantic Ridge on 0 to 80 Myr old seafloor. We calculate S-to-P (Sp) receiver functions and perform waveform modeling. We jointly interpret with shear-wave velocity tomography from surface waves and magnetotelluric (MT) imaging to take advantage of a range of resolutions and sensitivities and illuminate the structure of the oceanic lithosphere and the underlying asthenosphere. We image a tectonic plate thickness that increases with age in one location but undulates in another location. We infer thin and slightly thicker melt channels and punctuated regions of ascending partial melt several hundred kilometers off the ridge axis. This suggests melt persists over geologic timescales, although its character is dynamic, with implications for the lithosphere–asthenosphere boundary (LAB) and the driving forces of the plates. Ascending melt intermittently feeds melt channels at the base of the plate. The associated melt-enhanced buoyancy increases the influence of ridge-push in driving plate motions, whereas the channelized melt reduces the resistance of the plates to motion. Therefore, melt dynamics may play a larger role in controlling plate tectonics than previously thought.
oceanic lithosphere–asthenosphere boundary, seismology, Mid-Atlantic Ridge, plate tectonics, receiver functions, melt dynamics
0012-821X
Rychert, Catherine A.
70cf1e3a-58ea-455a-918a-1d570c5e53c5
Tharimena, Saikiran
d035ee82-5c90-4dac-b0dd-202a55511e9f
Harmon, Nicholas
10d11a16-b8b0-4132-9354-652e72d8e830
Wang, Shunguo
f935a6b8-a8c1-46f0-975a-1d4aa56b5f11
Constable, Steven
f2ffd9c4-3738-435b-8a88-38dee97de7cc
Kendall, J. Michael
746f7fc0-ee9e-4436-89d6-a6f26cdec6aa
Bogiatzis, Petros
8fc5767f-51a2-4d3f-aab9-1ee9cfa9272d
Agius, Matthew R.
cb168c8d-0926-4c0d-951c-721fb4cf1ebf
Schlaphorst, David
ce763c91-8236-4eac-b256-b35a8613d62b
Rychert, Catherine A.
70cf1e3a-58ea-455a-918a-1d570c5e53c5
Tharimena, Saikiran
d035ee82-5c90-4dac-b0dd-202a55511e9f
Harmon, Nicholas
10d11a16-b8b0-4132-9354-652e72d8e830
Wang, Shunguo
f935a6b8-a8c1-46f0-975a-1d4aa56b5f11
Constable, Steven
f2ffd9c4-3738-435b-8a88-38dee97de7cc
Kendall, J. Michael
746f7fc0-ee9e-4436-89d6-a6f26cdec6aa
Bogiatzis, Petros
8fc5767f-51a2-4d3f-aab9-1ee9cfa9272d
Agius, Matthew R.
cb168c8d-0926-4c0d-951c-721fb4cf1ebf
Schlaphorst, David
ce763c91-8236-4eac-b256-b35a8613d62b

Rychert, Catherine A., Tharimena, Saikiran, Harmon, Nicholas, Wang, Shunguo, Constable, Steven, Kendall, J. Michael, Bogiatzis, Petros, Agius, Matthew R. and Schlaphorst, David (2021) A dynamic lithosphere–asthenosphere boundary near the equatorial Mid-Atlantic Ridge. Earth and Planetary Science Letters, 566, [116949]. (doi:10.1016/j.epsl.2021.116949).

Record type: Article

Abstract

In plate tectonic theory a weak asthenosphere is required to facilitate the motions of the rigid plates. Partial melt could weaken the mantle, in turn impacting convection, but to date the existence of persistent melt has remained controversial. A wide range of scenarios has been reported in terms of the location, amount and pathways of melt. Here we use data collected by 39 ocean bottom seismometers deployed near the equatorial Mid-Atlantic Ridge on 0 to 80 Myr old seafloor. We calculate S-to-P (Sp) receiver functions and perform waveform modeling. We jointly interpret with shear-wave velocity tomography from surface waves and magnetotelluric (MT) imaging to take advantage of a range of resolutions and sensitivities and illuminate the structure of the oceanic lithosphere and the underlying asthenosphere. We image a tectonic plate thickness that increases with age in one location but undulates in another location. We infer thin and slightly thicker melt channels and punctuated regions of ascending partial melt several hundred kilometers off the ridge axis. This suggests melt persists over geologic timescales, although its character is dynamic, with implications for the lithosphere–asthenosphere boundary (LAB) and the driving forces of the plates. Ascending melt intermittently feeds melt channels at the base of the plate. The associated melt-enhanced buoyancy increases the influence of ridge-push in driving plate motions, whereas the channelized melt reduces the resistance of the plates to motion. Therefore, melt dynamics may play a larger role in controlling plate tectonics than previously thought.

Text
main_text_new_epsl_resub - Accepted Manuscript
Restricted to Repository staff only until 28 April 2022.
Request a copy

More information

Accepted/In Press date: 9 April 2021
e-pub ahead of print date: 28 April 2021
Published date: 15 July 2021
Keywords: oceanic lithosphere–asthenosphere boundary, seismology, Mid-Atlantic Ridge, plate tectonics, receiver functions, melt dynamics

Identifiers

Local EPrints ID: 449092
URI: http://eprints.soton.ac.uk/id/eprint/449092
ISSN: 0012-821X
PURE UUID: fc0a9300-5523-4223-8942-a44cc56e038c
ORCID for Nicholas Harmon: ORCID iD orcid.org/0000-0002-0731-768X
ORCID for Petros Bogiatzis: ORCID iD orcid.org/0000-0003-1902-7476

Catalogue record

Date deposited: 17 May 2021 16:32
Last modified: 18 May 2021 01:54

Export record

Altmetrics

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×