Disequilibrium degassing model determination of the 3He concentration and 3He/22Ne of the MORB and OIB mantle sources
Models of the dynamics of eruptive degassing provide a unique insight into the pre-eruptive concentrations of the major volatiles (CO2, H2O), noble gases, and the mantle reservoirs supplying them: a fundamental component in describing the accretion and evolution of the Earth. We investigate and deve...
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ftumanchesterpub:oai:pure.atira.dk:publications/a4a30455-574e-419b-8f18-983d6c8a5c9b 2023-11-12T04:19:31+01:00 Disequilibrium degassing model determination of the 3He concentration and 3He/22Ne of the MORB and OIB mantle sources Weston, Bridget Burgess, Ray Ballentine, Christopher J 2015-01-15 https://research.manchester.ac.uk/en/publications/a4a30455-574e-419b-8f18-983d6c8a5c9b https://doi.org/10.1016/j.epsl.2014.11.021 eng eng info:eu-repo/semantics/restrictedAccess Weston , B , Burgess , R & Ballentine , C J 2015 , ' Disequilibrium degassing model determination of the 3He concentration and 3He/22Ne of the MORB and OIB mantle sources ' , Earth and Planetary Science Letters , vol. 410 , pp. 128-139 . https://doi.org/10.1016/j.epsl.2014.11.021 article 2015 ftumanchesterpub https://doi.org/10.1016/j.epsl.2014.11.021 2023-10-30T09:15:12Z Models of the dynamics of eruptive degassing provide a unique insight into the pre-eruptive concentrations of the major volatiles (CO2, H2O), noble gases, and the mantle reservoirs supplying them: a fundamental component in describing the accretion and evolution of the Earth. We investigate and develop a disequilibrium degassing model, exploring the parameters required to reproduce noble gas compositions observed in two ocean island basalt (OIB) and one mid-ocean ridge basalt (MORB) sample suites from the East Pacific Rise (EPR), Loihi Seamount, and Iceland. The original model assumed an identical loss of major volatile components for each degassing step (Gonnermann and Mukhopadhyay, 2007). We recalculate the major volatile vapor phase composition for each degassing step, taking account of the degassing history over previous steps. Final noble gas elemental ratios, using the same eruption parameters, can differ by orders of magnitude from the original model's calculations. We further adapt our model variant to take into account both decompression-driven degassing during magma ascent and degassing at constant pressure during sample quenching. Our results show that elemental ratios and noble gas concentrations can be effectively decoupled by the different degassing stages of an eruption. Ascent rate determines whether degassing during magma ascent is modeled as predominantly closed or open system degassing. The closed system conditions that dominate the slowly ascending MORB result in a less dramatic decrease in degassed elemental ratios than for the OIB models, consistent with the observed data. The MORB model also constrains the initial MORB source melt 3He/22Ne ratio, allowing that the MORB mantle could have a ratio as low as the OIB ratio, a feature required by steady state mantle models. The two OIB sample suites show very similar noble gas ratios and concentrations despite a large difference in final eruption pressures. We propose that this can fit our model if the effect of gas loss by quenching is ... Article in Journal/Newspaper Iceland Ocean Island The University of Manchester: Research Explorer Pacific Earth and Planetary Science Letters 410 128 139 |
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The University of Manchester: Research Explorer |
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ftumanchesterpub |
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English |
description |
Models of the dynamics of eruptive degassing provide a unique insight into the pre-eruptive concentrations of the major volatiles (CO2, H2O), noble gases, and the mantle reservoirs supplying them: a fundamental component in describing the accretion and evolution of the Earth. We investigate and develop a disequilibrium degassing model, exploring the parameters required to reproduce noble gas compositions observed in two ocean island basalt (OIB) and one mid-ocean ridge basalt (MORB) sample suites from the East Pacific Rise (EPR), Loihi Seamount, and Iceland. The original model assumed an identical loss of major volatile components for each degassing step (Gonnermann and Mukhopadhyay, 2007). We recalculate the major volatile vapor phase composition for each degassing step, taking account of the degassing history over previous steps. Final noble gas elemental ratios, using the same eruption parameters, can differ by orders of magnitude from the original model's calculations. We further adapt our model variant to take into account both decompression-driven degassing during magma ascent and degassing at constant pressure during sample quenching. Our results show that elemental ratios and noble gas concentrations can be effectively decoupled by the different degassing stages of an eruption. Ascent rate determines whether degassing during magma ascent is modeled as predominantly closed or open system degassing. The closed system conditions that dominate the slowly ascending MORB result in a less dramatic decrease in degassed elemental ratios than for the OIB models, consistent with the observed data. The MORB model also constrains the initial MORB source melt 3He/22Ne ratio, allowing that the MORB mantle could have a ratio as low as the OIB ratio, a feature required by steady state mantle models. The two OIB sample suites show very similar noble gas ratios and concentrations despite a large difference in final eruption pressures. We propose that this can fit our model if the effect of gas loss by quenching is ... |
format |
Article in Journal/Newspaper |
author |
Weston, Bridget Burgess, Ray Ballentine, Christopher J |
spellingShingle |
Weston, Bridget Burgess, Ray Ballentine, Christopher J Disequilibrium degassing model determination of the 3He concentration and 3He/22Ne of the MORB and OIB mantle sources |
author_facet |
Weston, Bridget Burgess, Ray Ballentine, Christopher J |
author_sort |
Weston, Bridget |
title |
Disequilibrium degassing model determination of the 3He concentration and 3He/22Ne of the MORB and OIB mantle sources |
title_short |
Disequilibrium degassing model determination of the 3He concentration and 3He/22Ne of the MORB and OIB mantle sources |
title_full |
Disequilibrium degassing model determination of the 3He concentration and 3He/22Ne of the MORB and OIB mantle sources |
title_fullStr |
Disequilibrium degassing model determination of the 3He concentration and 3He/22Ne of the MORB and OIB mantle sources |
title_full_unstemmed |
Disequilibrium degassing model determination of the 3He concentration and 3He/22Ne of the MORB and OIB mantle sources |
title_sort |
disequilibrium degassing model determination of the 3he concentration and 3he/22ne of the morb and oib mantle sources |
publishDate |
2015 |
url |
https://research.manchester.ac.uk/en/publications/a4a30455-574e-419b-8f18-983d6c8a5c9b https://doi.org/10.1016/j.epsl.2014.11.021 |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
Iceland Ocean Island |
genre_facet |
Iceland Ocean Island |
op_source |
Weston , B , Burgess , R & Ballentine , C J 2015 , ' Disequilibrium degassing model determination of the 3He concentration and 3He/22Ne of the MORB and OIB mantle sources ' , Earth and Planetary Science Letters , vol. 410 , pp. 128-139 . https://doi.org/10.1016/j.epsl.2014.11.021 |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1016/j.epsl.2014.11.021 |
container_title |
Earth and Planetary Science Letters |
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410 |
container_start_page |
128 |
op_container_end_page |
139 |
_version_ |
1782335925756362752 |