Origin of geochemically heterogeneous mid-ocean ridge basalts from the Macquarie Ridge Complex, SW Pacific
TheMacquarie Ridge Complex (MRC), located at the Australian–Pacific plate boundary south of New Zealand, is a rugged bathymetric ridge comprising a series of submarine seamounts and Macquarie Island, the only subaerial portion of the complex. Mid-ocean ridge basalts (MORBs) from Macquarie Island sho...
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ftunivgeneve:oai:unige.ch:aou:unige:151434 2023-10-01T03:57:19+02:00 Origin of geochemically heterogeneous mid-ocean ridge basalts from the Macquarie Ridge Complex, SW Pacific Jiang, Qiang Merle, Renaud E. Jourdan, Fred Olierook, Hugo K.H. Chiaradia, Massimo Evans, Katy A. Wang, Xuan-Ce Conway, Chris E. Bostock, Helen C. Wysoczanski, Richard J. 2021 https://archive-ouverte.unige.ch/unige:151434 eng eng info:eu-repo/semantics/altIdentifier/doi/10.1016/j.lithos.2020.105893 https://archive-ouverte.unige.ch/unige:151434 unige:151434 info:eu-repo/semantics/restrictedAccess ISSN: 0024-4937 Lithos, vol. 380-381, no. 105893 (2021) info:eu-repo/classification/ddc/550 Balleny plume HIMU Macquarie Island Mantle metasomatism Pyroxenite Zealandia info:eu-repo/semantics/article Text Article scientifique info:eu-repo/semantics/publishedVersion 2021 ftunivgeneve https://doi.org/10.1016/j.lithos.2020.105893 2023-09-07T08:03:21Z TheMacquarie Ridge Complex (MRC), located at the Australian–Pacific plate boundary south of New Zealand, is a rugged bathymetric ridge comprising a series of submarine seamounts and Macquarie Island, the only subaerial portion of the complex. Mid-ocean ridge basalts (MORBs) from Macquarie Island show various enrichments in incompatible elements with compositions ranging from typical normal MORB to enriched MORB. However, these basalts have isotopic compositions trending towards a high μ-like (μ=238U/204Pb; HIMU) mantle component, which is unusual for MORB-type rocks. The origin of this mantle signature is not understood, and it is unclear whether this isotopic signature is characteristic of the entire MRC or unique to Macquarie Island. Here we report new major and trace element abundances, and Sr, Nd, and Pb isotopes for samples from the MRC seamounts and fromnew sampling sites onMacquarie Island. The geochemical and isotopic data show that the entire MRC comprises normal to enriched MORB. Mixing modelling indicates that the heterogeneous isotopic signatures of the MRC basalts are not derived from contamination of the nearby Balleny mantle plume but have affinities with that of the Cenozoic Zealandia intraplate HIMU-like basalts.We propose that the heterogeneous geochemical signatures of the MRC basalts are derived from amphibole-bearing garnet pyroxenite veins, which is supported by the rare earth element partial melting modelling and strong correlations between Nd and Pb isotopic ratios vs La/Sm.We posit that the pyroxenite veins were generated in the oceanic lithospheric mantle, which was metasomatised by hydrous and carbonatitic fluids/melts derived either from delaminated, metasomatised Zealandia subcontinental lithosphere mantle, or from subducted material in the asthenosphere. The subductedmaterial could be derived fromancient and/or recent subduction along the former east Gondwana margin. Article in Journal/Newspaper Macquarie Island Université de Genève: Archive ouverte UNIGE New Zealand Pacific Lithos 380-381 105893 |
institution |
Open Polar |
collection |
Université de Genève: Archive ouverte UNIGE |
op_collection_id |
ftunivgeneve |
language |
English |
topic |
info:eu-repo/classification/ddc/550 Balleny plume HIMU Macquarie Island Mantle metasomatism Pyroxenite Zealandia |
spellingShingle |
info:eu-repo/classification/ddc/550 Balleny plume HIMU Macquarie Island Mantle metasomatism Pyroxenite Zealandia Jiang, Qiang Merle, Renaud E. Jourdan, Fred Olierook, Hugo K.H. Chiaradia, Massimo Evans, Katy A. Wang, Xuan-Ce Conway, Chris E. Bostock, Helen C. Wysoczanski, Richard J. Origin of geochemically heterogeneous mid-ocean ridge basalts from the Macquarie Ridge Complex, SW Pacific |
topic_facet |
info:eu-repo/classification/ddc/550 Balleny plume HIMU Macquarie Island Mantle metasomatism Pyroxenite Zealandia |
description |
TheMacquarie Ridge Complex (MRC), located at the Australian–Pacific plate boundary south of New Zealand, is a rugged bathymetric ridge comprising a series of submarine seamounts and Macquarie Island, the only subaerial portion of the complex. Mid-ocean ridge basalts (MORBs) from Macquarie Island show various enrichments in incompatible elements with compositions ranging from typical normal MORB to enriched MORB. However, these basalts have isotopic compositions trending towards a high μ-like (μ=238U/204Pb; HIMU) mantle component, which is unusual for MORB-type rocks. The origin of this mantle signature is not understood, and it is unclear whether this isotopic signature is characteristic of the entire MRC or unique to Macquarie Island. Here we report new major and trace element abundances, and Sr, Nd, and Pb isotopes for samples from the MRC seamounts and fromnew sampling sites onMacquarie Island. The geochemical and isotopic data show that the entire MRC comprises normal to enriched MORB. Mixing modelling indicates that the heterogeneous isotopic signatures of the MRC basalts are not derived from contamination of the nearby Balleny mantle plume but have affinities with that of the Cenozoic Zealandia intraplate HIMU-like basalts.We propose that the heterogeneous geochemical signatures of the MRC basalts are derived from amphibole-bearing garnet pyroxenite veins, which is supported by the rare earth element partial melting modelling and strong correlations between Nd and Pb isotopic ratios vs La/Sm.We posit that the pyroxenite veins were generated in the oceanic lithospheric mantle, which was metasomatised by hydrous and carbonatitic fluids/melts derived either from delaminated, metasomatised Zealandia subcontinental lithosphere mantle, or from subducted material in the asthenosphere. The subductedmaterial could be derived fromancient and/or recent subduction along the former east Gondwana margin. |
format |
Article in Journal/Newspaper |
author |
Jiang, Qiang Merle, Renaud E. Jourdan, Fred Olierook, Hugo K.H. Chiaradia, Massimo Evans, Katy A. Wang, Xuan-Ce Conway, Chris E. Bostock, Helen C. Wysoczanski, Richard J. |
author_facet |
Jiang, Qiang Merle, Renaud E. Jourdan, Fred Olierook, Hugo K.H. Chiaradia, Massimo Evans, Katy A. Wang, Xuan-Ce Conway, Chris E. Bostock, Helen C. Wysoczanski, Richard J. |
author_sort |
Jiang, Qiang |
title |
Origin of geochemically heterogeneous mid-ocean ridge basalts from the Macquarie Ridge Complex, SW Pacific |
title_short |
Origin of geochemically heterogeneous mid-ocean ridge basalts from the Macquarie Ridge Complex, SW Pacific |
title_full |
Origin of geochemically heterogeneous mid-ocean ridge basalts from the Macquarie Ridge Complex, SW Pacific |
title_fullStr |
Origin of geochemically heterogeneous mid-ocean ridge basalts from the Macquarie Ridge Complex, SW Pacific |
title_full_unstemmed |
Origin of geochemically heterogeneous mid-ocean ridge basalts from the Macquarie Ridge Complex, SW Pacific |
title_sort |
origin of geochemically heterogeneous mid-ocean ridge basalts from the macquarie ridge complex, sw pacific |
publishDate |
2021 |
url |
https://archive-ouverte.unige.ch/unige:151434 |
geographic |
New Zealand Pacific |
geographic_facet |
New Zealand Pacific |
genre |
Macquarie Island |
genre_facet |
Macquarie Island |
op_source |
ISSN: 0024-4937 Lithos, vol. 380-381, no. 105893 (2021) |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1016/j.lithos.2020.105893 https://archive-ouverte.unige.ch/unige:151434 unige:151434 |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1016/j.lithos.2020.105893 |
container_title |
Lithos |
container_volume |
380-381 |
container_start_page |
105893 |
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1778528514237005824 |