Reappraisal of uranium-series isotope data in Kamchatka lavas: implications for continental arc magma genesis
Uranium-series isotopes can be used to determine constraints on the timescale of slab dehydration and melt production at subduction zones. However, interpretations of U–Th–Ra data suggest very different timescales of slab dehydration. Here, we present new U–Th–Ra data from Kamchatka along with a num...
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ftunivwollongong:oai:ro.uow.edu.au:smhpapers-2375 2023-05-15T16:58:37+02:00 Reappraisal of uranium-series isotope data in Kamchatka lavas: implications for continental arc magma genesis Dosseto, Anthony Turner, Simon 2014-01-01T08:00:00Z application/pdf https://ro.uow.edu.au/smhpapers/1357 https://ro.uow.edu.au/cgi/viewcontent.cgi?article=2375&context=smhpapers unknown Research Online https://ro.uow.edu.au/smhpapers/1357 https://ro.uow.edu.au/cgi/viewcontent.cgi?article=2375&context=smhpapers Faculty of Science, Medicine and Health - Papers: part A magma arc continental implications lavas genesis kamchatka reappraisal data isotope series uranium Medicine and Health Sciences Social and Behavioral Sciences article 2014 ftunivwollongong 2020-02-25T10:58:35Z Uranium-series isotopes can be used to determine constraints on the timescale of slab dehydration and melt production at subduction zones. However, interpretations of U–Th–Ra data suggest very different timescales of slab dehydration. Here, we present new U–Th–Ra data from Kamchatka along with a number of alternative models for production of radioactive disequilibrium. Variations in (226Ra/230Th) and (231Pa/235U) activity ratios are best explained by crystal fractionation with host rock assimilation for a duration of less than c. 6000 years. The association of the largest 226Ra excesses with high Sr/Th in the most primitive lavas suggests that Ra–Th fractionation is controlled by slab dehydration less than 10 ka ago. We show that U–Th data can be explained by dynamic melting of a recently (<10 ka) metasomatized mantle wedge. Dynamic melting of an oxidized source metasomatized several hundreds of thousands of years ago cannot produce significant 231Pa excess. Because 238U–230Th disequilibrium is inferred to be controlled by partial melting, there is no requirement for multi-stage slab dehydration commencing ∼150 ka. We suggest that Ra–Th disequilibria constrain the timing of slab dehydration, whilst U–Th fractionation is dominated by partial melting, at least at the Kamchatka arc. Article in Journal/Newspaper Kamchatka University of Wollongong, Australia: Research Online |
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Open Polar |
collection |
University of Wollongong, Australia: Research Online |
op_collection_id |
ftunivwollongong |
language |
unknown |
topic |
magma arc continental implications lavas genesis kamchatka reappraisal data isotope series uranium Medicine and Health Sciences Social and Behavioral Sciences |
spellingShingle |
magma arc continental implications lavas genesis kamchatka reappraisal data isotope series uranium Medicine and Health Sciences Social and Behavioral Sciences Dosseto, Anthony Turner, Simon Reappraisal of uranium-series isotope data in Kamchatka lavas: implications for continental arc magma genesis |
topic_facet |
magma arc continental implications lavas genesis kamchatka reappraisal data isotope series uranium Medicine and Health Sciences Social and Behavioral Sciences |
description |
Uranium-series isotopes can be used to determine constraints on the timescale of slab dehydration and melt production at subduction zones. However, interpretations of U–Th–Ra data suggest very different timescales of slab dehydration. Here, we present new U–Th–Ra data from Kamchatka along with a number of alternative models for production of radioactive disequilibrium. Variations in (226Ra/230Th) and (231Pa/235U) activity ratios are best explained by crystal fractionation with host rock assimilation for a duration of less than c. 6000 years. The association of the largest 226Ra excesses with high Sr/Th in the most primitive lavas suggests that Ra–Th fractionation is controlled by slab dehydration less than 10 ka ago. We show that U–Th data can be explained by dynamic melting of a recently (<10 ka) metasomatized mantle wedge. Dynamic melting of an oxidized source metasomatized several hundreds of thousands of years ago cannot produce significant 231Pa excess. Because 238U–230Th disequilibrium is inferred to be controlled by partial melting, there is no requirement for multi-stage slab dehydration commencing ∼150 ka. We suggest that Ra–Th disequilibria constrain the timing of slab dehydration, whilst U–Th fractionation is dominated by partial melting, at least at the Kamchatka arc. |
format |
Article in Journal/Newspaper |
author |
Dosseto, Anthony Turner, Simon |
author_facet |
Dosseto, Anthony Turner, Simon |
author_sort |
Dosseto, Anthony |
title |
Reappraisal of uranium-series isotope data in Kamchatka lavas: implications for continental arc magma genesis |
title_short |
Reappraisal of uranium-series isotope data in Kamchatka lavas: implications for continental arc magma genesis |
title_full |
Reappraisal of uranium-series isotope data in Kamchatka lavas: implications for continental arc magma genesis |
title_fullStr |
Reappraisal of uranium-series isotope data in Kamchatka lavas: implications for continental arc magma genesis |
title_full_unstemmed |
Reappraisal of uranium-series isotope data in Kamchatka lavas: implications for continental arc magma genesis |
title_sort |
reappraisal of uranium-series isotope data in kamchatka lavas: implications for continental arc magma genesis |
publisher |
Research Online |
publishDate |
2014 |
url |
https://ro.uow.edu.au/smhpapers/1357 https://ro.uow.edu.au/cgi/viewcontent.cgi?article=2375&context=smhpapers |
genre |
Kamchatka |
genre_facet |
Kamchatka |
op_source |
Faculty of Science, Medicine and Health - Papers: part A |
op_relation |
https://ro.uow.edu.au/smhpapers/1357 https://ro.uow.edu.au/cgi/viewcontent.cgi?article=2375&context=smhpapers |
_version_ |
1766050668768919552 |