A 210Pb-226Ra-230Th-238U study of Klyuchevskoy and Bezymianny volcanoes, Kamchatka
Lavas from Klyuchevskoy and Bezymianny volcanoes, Kamchatka, appear to show a link between the extent of partial melting in their mantle source region and the subsequent degree of fractionation suffered by the magmas during passage through the crust. This fractionation may have occurred on timescale...
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ftmacquarieunicr:oai:https://researchers.mq.edu.au:publications/8298051c-5993-4fe2-8905-eca727ae8c82 2024-06-09T07:47:24+00:00 A 210Pb-226Ra-230Th-238U study of Klyuchevskoy and Bezymianny volcanoes, Kamchatka Turner, Simon Sims, Kenneth W W Reagan, Mark Cook, Craig 2007-10-01 https://researchers.mq.edu.au/en/publications/8298051c-5993-4fe2-8905-eca727ae8c82 https://doi.org/10.1016/j.gca.2007.08.006 http://www.scopus.com/inward/record.url?scp=35248859183&partnerID=8YFLogxK eng eng info:eu-repo/semantics/closedAccess Turner , S , Sims , K W W , Reagan , M & Cook , C 2007 , ' A 210Pb-226Ra-230Th-238U study of Klyuchevskoy and Bezymianny volcanoes, Kamchatka ' , Geochimica et Cosmochimica Acta , vol. 71 , no. 19 , pp. 4771-4785 . https://doi.org/10.1016/j.gca.2007.08.006 article 2007 ftmacquarieunicr https://doi.org/10.1016/j.gca.2007.08.006 2024-05-16T14:21:49Z Lavas from Klyuchevskoy and Bezymianny volcanoes, Kamchatka, appear to show a link between the extent of partial melting in their mantle source region and the subsequent degree of fractionation suffered by the magmas during passage through the crust. This fractionation may have occurred on timescales significantly less than 1000 years if observed 226 Ra excesses largely reflect variable residual porosity in the source melting region. Unlike most arc lavas, those with the highest MgO contents and Ba/Th ratios have the lowest 226 Ra excess. Forward models suggest that those portions of the source which had undergone the greatest addition of U by fluids from the subducting plate also underwent the greatest extents of partial melting at the highest residual porosity. At Kluchevskoy, a change from eruption of high-MgO to high-Al 2 O 3 basaltic andesites around 1945 is reflected in an increase in size of 226 Ra excess which seems to require a simultaneous decrease in residual porosity and suggests a rapid changes in the melting regime. The eruption of andesites at Bezyminanny, simultaneous with the eruption of basaltic andesites at Klyuchevskoy, further suggests that different degree melts produced at differing residual porosity can be formed and extracted from the melt region at the same time. Thus, the melting processes beneath Klyuchevskoy and Bezyminanny are demonstrably complex. They have clearly been influenced by both fluid addition from the subducting plate and extension and decompression beneath the Central Kamchatka Depression. Finally, the 210 Pb data are, with one or two exceptions, in equilibrium with 226 Ra, suggesting that there was restricted relative magma-gas movement in this highly productive magmatic system. Article in Journal/Newspaper Kamchatka Macquarie University Research Portal Geochimica et Cosmochimica Acta 71 19 4771 4785 |
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Macquarie University Research Portal |
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ftmacquarieunicr |
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English |
description |
Lavas from Klyuchevskoy and Bezymianny volcanoes, Kamchatka, appear to show a link between the extent of partial melting in their mantle source region and the subsequent degree of fractionation suffered by the magmas during passage through the crust. This fractionation may have occurred on timescales significantly less than 1000 years if observed 226 Ra excesses largely reflect variable residual porosity in the source melting region. Unlike most arc lavas, those with the highest MgO contents and Ba/Th ratios have the lowest 226 Ra excess. Forward models suggest that those portions of the source which had undergone the greatest addition of U by fluids from the subducting plate also underwent the greatest extents of partial melting at the highest residual porosity. At Kluchevskoy, a change from eruption of high-MgO to high-Al 2 O 3 basaltic andesites around 1945 is reflected in an increase in size of 226 Ra excess which seems to require a simultaneous decrease in residual porosity and suggests a rapid changes in the melting regime. The eruption of andesites at Bezyminanny, simultaneous with the eruption of basaltic andesites at Klyuchevskoy, further suggests that different degree melts produced at differing residual porosity can be formed and extracted from the melt region at the same time. Thus, the melting processes beneath Klyuchevskoy and Bezyminanny are demonstrably complex. They have clearly been influenced by both fluid addition from the subducting plate and extension and decompression beneath the Central Kamchatka Depression. Finally, the 210 Pb data are, with one or two exceptions, in equilibrium with 226 Ra, suggesting that there was restricted relative magma-gas movement in this highly productive magmatic system. |
format |
Article in Journal/Newspaper |
author |
Turner, Simon Sims, Kenneth W W Reagan, Mark Cook, Craig |
spellingShingle |
Turner, Simon Sims, Kenneth W W Reagan, Mark Cook, Craig A 210Pb-226Ra-230Th-238U study of Klyuchevskoy and Bezymianny volcanoes, Kamchatka |
author_facet |
Turner, Simon Sims, Kenneth W W Reagan, Mark Cook, Craig |
author_sort |
Turner, Simon |
title |
A 210Pb-226Ra-230Th-238U study of Klyuchevskoy and Bezymianny volcanoes, Kamchatka |
title_short |
A 210Pb-226Ra-230Th-238U study of Klyuchevskoy and Bezymianny volcanoes, Kamchatka |
title_full |
A 210Pb-226Ra-230Th-238U study of Klyuchevskoy and Bezymianny volcanoes, Kamchatka |
title_fullStr |
A 210Pb-226Ra-230Th-238U study of Klyuchevskoy and Bezymianny volcanoes, Kamchatka |
title_full_unstemmed |
A 210Pb-226Ra-230Th-238U study of Klyuchevskoy and Bezymianny volcanoes, Kamchatka |
title_sort |
210pb-226ra-230th-238u study of klyuchevskoy and bezymianny volcanoes, kamchatka |
publishDate |
2007 |
url |
https://researchers.mq.edu.au/en/publications/8298051c-5993-4fe2-8905-eca727ae8c82 https://doi.org/10.1016/j.gca.2007.08.006 http://www.scopus.com/inward/record.url?scp=35248859183&partnerID=8YFLogxK |
genre |
Kamchatka |
genre_facet |
Kamchatka |
op_source |
Turner , S , Sims , K W W , Reagan , M & Cook , C 2007 , ' A 210Pb-226Ra-230Th-238U study of Klyuchevskoy and Bezymianny volcanoes, Kamchatka ' , Geochimica et Cosmochimica Acta , vol. 71 , no. 19 , pp. 4771-4785 . https://doi.org/10.1016/j.gca.2007.08.006 |
op_rights |
info:eu-repo/semantics/closedAccess |
op_doi |
https://doi.org/10.1016/j.gca.2007.08.006 |
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Geochimica et Cosmochimica Acta |
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71 |
container_issue |
19 |
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4771 |
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4785 |
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