A multi-siderophile element connection between volcanic hotspots and Earth's core
The existence of resolvable 182W/184W deficits in modern ocean island basalts (OIB) relative to the bulk silicate Earth has raised questions about the relationship of these rocks to Earth's core. However, because the core is expected to host high abundances of highly siderophile elements (HSE:...
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ftethz:oai:www.research-collection.ethz.ch:20.500.11850/622224 2023-11-12T04:19:34+01:00 A multi-siderophile element connection between volcanic hotspots and Earth's core Peters, Bradley J. Mundl-Petermeier, Andrea Finlayson, Valerie A. 2023-09-15 application/application/pdf https://hdl.handle.net/20.500.11850/622224 https://doi.org/10.3929/ethz-b-000622224 en eng Elsevier info:eu-repo/semantics/altIdentifier/doi/10.1016/j.epsl.2023.118285 info:eu-repo/semantics/altIdentifier/wos/001032691100001 http://hdl.handle.net/20.500.11850/622224 doi:10.3929/ethz-b-000622224 info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International Earth and Planetary Science Letters, 618 mantle plume core-mantle interaction metal-silicate equilibration siderophile elements tungsten isotopes early Earth processes info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2023 ftethz https://doi.org/20.500.11850/62222410.3929/ethz-b-00062222410.1016/j.epsl.2023.118285 2023-10-22T23:50:45Z The existence of resolvable 182W/184W deficits in modern ocean island basalts (OIB) relative to the bulk silicate Earth has raised questions about the relationship of these rocks to Earth's core. However, because the core is expected to host high abundances of highly siderophile elements (HSE: Os, Ir, Ru, Pt, Pd, Re), it would be expected that such heterogeneity is accompanied by correlating variability in HSE abundances among OIB, but this has not been observed. We report instead a relationship between the W isotopic compositions and Ru/Ir ratios of Hawai‘i and Iceland OIB, which represent two of Earth's primary mantle plumes. Previous studies have highlighted the unique behavior of Ru relative to Os and Ir during metal-silicate fractionation, particularly when sulfide phases are segregated with metal. Using the information from these studies, we construct models predicting the consequences for HSE fractionation of various scenarios in which 182W/184W deficits can be created. These models show that the observed trends are likely inconsistent with modern, active core-mantle interaction at the CMB, and instead the observed low-Ru/Ir, low-182W/184W OIB are best explained by metal-silicate interaction that happened at significantly lower pressures. Such conditions may reflect what is expected for metal-silicate equilibration during the process of core formation itself, meaning that the deep mantle sources of OIB, such as ultra-low velocity zones, may instead reflect preserved relics of core formation. An ancient origin for distinct domains now residing at the core-mantle boundary is consistent with geophysical and petrological observations, for example that the Mg/Fe ratio of ferropericlase in the D″ layer is in significant disequilibrium with the modern core. Additional work is required to constrain the behavior of HSE during silicate differentiation processes that may also generate low 182W/184W ratios. However, if modern OIB represent a direct link to the ancient processes of core formation, future geochemical ... Article in Journal/Newspaper Iceland Ocean Island ETH Zürich Research Collection |
institution |
Open Polar |
collection |
ETH Zürich Research Collection |
op_collection_id |
ftethz |
language |
English |
topic |
mantle plume core-mantle interaction metal-silicate equilibration siderophile elements tungsten isotopes early Earth processes |
spellingShingle |
mantle plume core-mantle interaction metal-silicate equilibration siderophile elements tungsten isotopes early Earth processes Peters, Bradley J. Mundl-Petermeier, Andrea Finlayson, Valerie A. A multi-siderophile element connection between volcanic hotspots and Earth's core |
topic_facet |
mantle plume core-mantle interaction metal-silicate equilibration siderophile elements tungsten isotopes early Earth processes |
description |
The existence of resolvable 182W/184W deficits in modern ocean island basalts (OIB) relative to the bulk silicate Earth has raised questions about the relationship of these rocks to Earth's core. However, because the core is expected to host high abundances of highly siderophile elements (HSE: Os, Ir, Ru, Pt, Pd, Re), it would be expected that such heterogeneity is accompanied by correlating variability in HSE abundances among OIB, but this has not been observed. We report instead a relationship between the W isotopic compositions and Ru/Ir ratios of Hawai‘i and Iceland OIB, which represent two of Earth's primary mantle plumes. Previous studies have highlighted the unique behavior of Ru relative to Os and Ir during metal-silicate fractionation, particularly when sulfide phases are segregated with metal. Using the information from these studies, we construct models predicting the consequences for HSE fractionation of various scenarios in which 182W/184W deficits can be created. These models show that the observed trends are likely inconsistent with modern, active core-mantle interaction at the CMB, and instead the observed low-Ru/Ir, low-182W/184W OIB are best explained by metal-silicate interaction that happened at significantly lower pressures. Such conditions may reflect what is expected for metal-silicate equilibration during the process of core formation itself, meaning that the deep mantle sources of OIB, such as ultra-low velocity zones, may instead reflect preserved relics of core formation. An ancient origin for distinct domains now residing at the core-mantle boundary is consistent with geophysical and petrological observations, for example that the Mg/Fe ratio of ferropericlase in the D″ layer is in significant disequilibrium with the modern core. Additional work is required to constrain the behavior of HSE during silicate differentiation processes that may also generate low 182W/184W ratios. However, if modern OIB represent a direct link to the ancient processes of core formation, future geochemical ... |
format |
Article in Journal/Newspaper |
author |
Peters, Bradley J. Mundl-Petermeier, Andrea Finlayson, Valerie A. |
author_facet |
Peters, Bradley J. Mundl-Petermeier, Andrea Finlayson, Valerie A. |
author_sort |
Peters, Bradley J. |
title |
A multi-siderophile element connection between volcanic hotspots and Earth's core |
title_short |
A multi-siderophile element connection between volcanic hotspots and Earth's core |
title_full |
A multi-siderophile element connection between volcanic hotspots and Earth's core |
title_fullStr |
A multi-siderophile element connection between volcanic hotspots and Earth's core |
title_full_unstemmed |
A multi-siderophile element connection between volcanic hotspots and Earth's core |
title_sort |
multi-siderophile element connection between volcanic hotspots and earth's core |
publisher |
Elsevier |
publishDate |
2023 |
url |
https://hdl.handle.net/20.500.11850/622224 https://doi.org/10.3929/ethz-b-000622224 |
genre |
Iceland Ocean Island |
genre_facet |
Iceland Ocean Island |
op_source |
Earth and Planetary Science Letters, 618 |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1016/j.epsl.2023.118285 info:eu-repo/semantics/altIdentifier/wos/001032691100001 http://hdl.handle.net/20.500.11850/622224 doi:10.3929/ethz-b-000622224 |
op_rights |
info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International |
op_doi |
https://doi.org/20.500.11850/62222410.3929/ethz-b-00062222410.1016/j.epsl.2023.118285 |
_version_ |
1782335962477494272 |