Cardiff University | Prifysgol Caerdydd ORCA
Online Research @ Cardiff 
WelshClear Cookie - decide language by browser settings

The stability of dense oceanic crust near the core‐mantle boundary

Panton, James, Davies, J. Huw ORCID: https://orcid.org/0000-0003-2656-0260 and Myhill, Robert 2023. The stability of dense oceanic crust near the core‐mantle boundary. Journal of Geophysical Research: Solid Earth 128 (2) , e2022JB025610. 10.1029/2022jb025610

[thumbnail of 2022JB025610.pdf] PDF - Published Version
Available under License Creative Commons Attribution.

Download (5MB)
License URL: http://creativecommons.org/licenses/by/4.0/
License Start date: 28 January 2023

Abstract

The large low‐shear‐velocity provinces (LLSVPs) are thought to be thermo‐chemical in nature, with recycled oceanic crust (OC) being a contender for the source of the chemical heterogeneity. The melting process which forms OC concentrates heat producing elements (HPEs) within it which, over time, may cause any collected piles of OC to destabilize, limiting their suitability to explain LLSVPs. Despite this, most geodynamic studies which include recycling of OC consider only homogeneous heating rates. We perform a suite of spherical, three‐dimensional mantle convection simulations to investigate how buoyancy number, geochemical model and heating model affects the ability of recycled OC to accumulate at the core‐mantle boundary. Our results agree with others that only a narrow range of buoyancy numbers allow OC to form piles in the lower mantle which remain stable to present day. We demonstrate that heterogeneous radiogenic heating causes piles to destabilize more readily, reducing present day CMB coverage from 63% to 47%. Consequently, the choice of geochemical model can influence pile formation. Geochemical models which lead to high internal heating rates can cause more rapid replenishment of piles, increasing their longevity. Where piles do remain to present day, first order comparisons suggest that old (hot) OC material can produce seismic characteristics, such as Vs anomalies, similar to those of LLSVPs. Given the range of current density estimates for lower mantle mineral phases, subducted OC remains a contender for the chemical component of thermo‐chemical LLSVPs.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Earth and Environmental Sciences
Additional Information: License information from Publisher: LICENSE 1: URL: http://creativecommons.org/licenses/by/4.0/
Publisher: American Geophysical Union
ISSN: 2169-9313
Funders: NERC
Date of First Compliant Deposit: 7 February 2023
Date of Acceptance: 26 January 2023
Last Modified: 12 Jul 2023 04:33
URI: https://orca.cardiff.ac.uk/id/eprint/156555

Actions (repository staff only)

Edit Item Edit Item

Downloads

Downloads per month over past year

View more statistics