Halogen systematics (Cl, Br, I) in Mid-Ocean Ridge Basalts: A Macquarie Island case study
The abundance of halogens (Cl, Br and I) in the Earth's mantle has the potential to provide information about mantle metasomatism and volatile recycling in subduction zones. Basalt melts sample different parts of the Earth's mantle, but few data are available for Br or I in basalt melts, a...
Published in: | Geochimica et Cosmochimica Acta |
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ftanucanberra:oai:openresearch-repository.anu.edu.au:1885/63441 2024-01-14T10:08:34+01:00 Halogen systematics (Cl, Br, I) in Mid-Ocean Ridge Basalts: A Macquarie Island case study Kendrick, Mark Kamenetsky, Vadim S Phillips, David Honda, Masahiko http://hdl.handle.net/1885/63441 https://doi.org/10.1016/j.gca.2011.12.004 https://openresearch-repository.anu.edu.au/bitstream/1885/63441/5/f5625xPUB807_2012.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/63441/7/01_Kendrick_Halogen_systematics_%28Cl%2c_Br%2c_2012.pdf.jpg unknown Pergamon-Elsevier Ltd 1872-9533 http://hdl.handle.net/1885/63441 doi:10.1016/j.gca.2011.12.004 https://openresearch-repository.anu.edu.au/bitstream/1885/63441/5/f5625xPUB807_2012.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/63441/7/01_Kendrick_Halogen_systematics_%28Cl%2c_Br%2c_2012.pdf.jpg Geochimica et Cosmochimica Acta Keywords: abundance carbon dioxide correlation degassing fractional crystallization halogen mantle source metasomatism mid-ocean ridge basalt partial melting subduction zone trace element Macquarie Island Journal article ftanucanberra https://doi.org/10.1016/j.gca.2011.12.004 2023-12-15T09:33:37Z The abundance of halogens (Cl, Br and I) in the Earth's mantle has the potential to provide information about mantle metasomatism and volatile recycling in subduction zones. Basalt melts sample different parts of the Earth's mantle, but few data are available for Br or I in basalt melts, and the relative partitioning behaviour of these elements has not been investigated rigorously. To address these issues, we determined the abundances of Cl, Br and I in enriched Mid-Ocean Ridge Basalt (E-MORB) glasses from Macquarie Island in the southwest Pacific. The Macquarie Island glasses are fairly typical of Pacific MORB with MgO of ∼5.5. to 9wt%,87Sr/86Sr of 0.70257-0.70276,143Nd/144Nd of 0.51300-0.51306 and3He/4He of ∼8Ra. These glasses provide a unique opportunity to investigate halogen partitioning behaviour, because their variable MgO contents and trace element signatures (e.g. La/Sm ∼1.4-7.9) result from different degrees of partial melting and fractional crystallisation. The combined measurement of Br/Cl, I/Cl and K/Cl, together with correlations between Cl and other trace elements, demonstrate that the halogens in the Macquarie Island glasses had a mantle source and were not influenced by seawater contamination. Log-log correlation diagrams indicate that Cl, Br and K were not statistically fractionated during partial melting, crystallisation or degassing of CO2 from these melts. The behaviour of I is less well constrained and minor fractionation of I/Cl cannot be precluded during multi-stage melting and enrichment processes. The data indicate the mantle source of the Macquarie Island glasses was characterised by K/Cl of 13±4, Br/Cl of (3.7±0.5)×10-3 and I/Cl of (130±100)×10-6 (2σ uncertainties; weight ratios). The K/Cl ratio of the Macquarie Island glasses is equivalent to the median of all published MORB data. This suggests the Br/Cl and I/Cl values may also be representative of average MORB mantle values. Article in Journal/Newspaper Macquarie Island Australian National University: ANU Digital Collections Pacific Geochimica et Cosmochimica Acta 81 82 93 |
institution |
Open Polar |
collection |
Australian National University: ANU Digital Collections |
op_collection_id |
ftanucanberra |
language |
unknown |
topic |
Keywords: abundance carbon dioxide correlation degassing fractional crystallization halogen mantle source metasomatism mid-ocean ridge basalt partial melting subduction zone trace element Macquarie Island |
spellingShingle |
Keywords: abundance carbon dioxide correlation degassing fractional crystallization halogen mantle source metasomatism mid-ocean ridge basalt partial melting subduction zone trace element Macquarie Island Kendrick, Mark Kamenetsky, Vadim S Phillips, David Honda, Masahiko Halogen systematics (Cl, Br, I) in Mid-Ocean Ridge Basalts: A Macquarie Island case study |
topic_facet |
Keywords: abundance carbon dioxide correlation degassing fractional crystallization halogen mantle source metasomatism mid-ocean ridge basalt partial melting subduction zone trace element Macquarie Island |
description |
The abundance of halogens (Cl, Br and I) in the Earth's mantle has the potential to provide information about mantle metasomatism and volatile recycling in subduction zones. Basalt melts sample different parts of the Earth's mantle, but few data are available for Br or I in basalt melts, and the relative partitioning behaviour of these elements has not been investigated rigorously. To address these issues, we determined the abundances of Cl, Br and I in enriched Mid-Ocean Ridge Basalt (E-MORB) glasses from Macquarie Island in the southwest Pacific. The Macquarie Island glasses are fairly typical of Pacific MORB with MgO of ∼5.5. to 9wt%,87Sr/86Sr of 0.70257-0.70276,143Nd/144Nd of 0.51300-0.51306 and3He/4He of ∼8Ra. These glasses provide a unique opportunity to investigate halogen partitioning behaviour, because their variable MgO contents and trace element signatures (e.g. La/Sm ∼1.4-7.9) result from different degrees of partial melting and fractional crystallisation. The combined measurement of Br/Cl, I/Cl and K/Cl, together with correlations between Cl and other trace elements, demonstrate that the halogens in the Macquarie Island glasses had a mantle source and were not influenced by seawater contamination. Log-log correlation diagrams indicate that Cl, Br and K were not statistically fractionated during partial melting, crystallisation or degassing of CO2 from these melts. The behaviour of I is less well constrained and minor fractionation of I/Cl cannot be precluded during multi-stage melting and enrichment processes. The data indicate the mantle source of the Macquarie Island glasses was characterised by K/Cl of 13±4, Br/Cl of (3.7±0.5)×10-3 and I/Cl of (130±100)×10-6 (2σ uncertainties; weight ratios). The K/Cl ratio of the Macquarie Island glasses is equivalent to the median of all published MORB data. This suggests the Br/Cl and I/Cl values may also be representative of average MORB mantle values. |
format |
Article in Journal/Newspaper |
author |
Kendrick, Mark Kamenetsky, Vadim S Phillips, David Honda, Masahiko |
author_facet |
Kendrick, Mark Kamenetsky, Vadim S Phillips, David Honda, Masahiko |
author_sort |
Kendrick, Mark |
title |
Halogen systematics (Cl, Br, I) in Mid-Ocean Ridge Basalts: A Macquarie Island case study |
title_short |
Halogen systematics (Cl, Br, I) in Mid-Ocean Ridge Basalts: A Macquarie Island case study |
title_full |
Halogen systematics (Cl, Br, I) in Mid-Ocean Ridge Basalts: A Macquarie Island case study |
title_fullStr |
Halogen systematics (Cl, Br, I) in Mid-Ocean Ridge Basalts: A Macquarie Island case study |
title_full_unstemmed |
Halogen systematics (Cl, Br, I) in Mid-Ocean Ridge Basalts: A Macquarie Island case study |
title_sort |
halogen systematics (cl, br, i) in mid-ocean ridge basalts: a macquarie island case study |
publisher |
Pergamon-Elsevier Ltd |
url |
http://hdl.handle.net/1885/63441 https://doi.org/10.1016/j.gca.2011.12.004 https://openresearch-repository.anu.edu.au/bitstream/1885/63441/5/f5625xPUB807_2012.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/63441/7/01_Kendrick_Halogen_systematics_%28Cl%2c_Br%2c_2012.pdf.jpg |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
Macquarie Island |
genre_facet |
Macquarie Island |
op_source |
Geochimica et Cosmochimica Acta |
op_relation |
1872-9533 http://hdl.handle.net/1885/63441 doi:10.1016/j.gca.2011.12.004 https://openresearch-repository.anu.edu.au/bitstream/1885/63441/5/f5625xPUB807_2012.pdf.jpg https://openresearch-repository.anu.edu.au/bitstream/1885/63441/7/01_Kendrick_Halogen_systematics_%28Cl%2c_Br%2c_2012.pdf.jpg |
op_doi |
https://doi.org/10.1016/j.gca.2011.12.004 |
container_title |
Geochimica et Cosmochimica Acta |
container_volume |
81 |
container_start_page |
82 |
op_container_end_page |
93 |
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1788062983898791936 |