Deciphering variable mantle sources and hydrous inputs to arc magmas in Kamchatka
The chemistry of primitive arc rocks provides a window into compositional variability in the mantle wedge, as well as slab-derived inputs to subduction-related magmatism. However, in the long-term cycling of elements between Earth's internal and external reservoirs, a key unknown is the importa...
Published in: | Earth and Planetary Science Letters |
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Online Access: | http://dro.dur.ac.uk/32658/ http://dro.dur.ac.uk/32658/1/32658.pdf https://doi.org/10.1016/j.epsl.2021.116848 |
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ftunivdurham:oai:dro.dur.ac.uk.OAI2:32658 2023-05-15T16:58:57+02:00 Deciphering variable mantle sources and hydrous inputs to arc magmas in Kamchatka Iveson, Alexander A. Humphreys, Madeleine C.S. Savov, Ivan P. de Hoog, Jan C.M. Turner, Stephen J. Churikova, Tatiana G. Macpherson, Colin. G. Mather, Tamsin A. Gordeychik, Boris N. Tomanikova, Lubomira Agostini, Samuele Hammond, Keiji Pyle, David M. Cooper, George F. 2021-05 application/pdf http://dro.dur.ac.uk/32658/ http://dro.dur.ac.uk/32658/1/32658.pdf https://doi.org/10.1016/j.epsl.2021.116848 unknown Elsevier dro:32658 issn:0012-821X doi:10.1016/j.epsl.2021.116848 http://dro.dur.ac.uk/32658/ https://doi.org/10.1016/j.epsl.2021.116848 http://dro.dur.ac.uk/32658/1/32658.pdf ©2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). CC-BY Earth and planetary science letters, 2021, Vol.562 [Peer Reviewed Journal] Article PeerReviewed 2021 ftunivdurham https://doi.org/10.1016/j.epsl.2021.116848 2021-03-04T23:23:11Z The chemistry of primitive arc rocks provides a window into compositional variability in the mantle wedge, as well as slab-derived inputs to subduction-related magmatism. However, in the long-term cycling of elements between Earth's internal and external reservoirs, a key unknown is the importance of retaining mobile elements within the subduction system, through subduction-related metasomatism of the mantle. To address these questions, we have analysed olivine-hosted melt inclusions and corresponding bulk rocks from the Kamchatka arc. Suites of melt inclusions record evidence for entrapment along melt mixing arrays during assembly of diverse parental magma compositions. Systematic variations in parental magma B/Zr, Nb/Zr, Ce/B, and B are also apparent among the different eruptive centres studied. These element ratios constrain the nature of subduction-related metasomatism and provide evidence for ambient mantle heterogeneity and variable degrees of mantle melting. High Nb/Zr and low B/Zr in back-arc rocks indicate smaller degree melts, lower slab-derived inputs, but relatively enriched mantle compositions. Similarly, small monogenetic eruptive centres located away from the main stratocones also tend to erupt magmas with relatively lower slab contribution and overall smaller melting degrees. Conversely, arc-front compositions reflect greater slab contributions and larger degree melts of a more depleted ambient mantle. Across-arc variations in B (ranging from ca. ‰ in the rear-arc and Sredinny Ridge to ‰ in the Central Kamchatka Depression) are generally consistent with variable addition of an isotopically heavy slab-derived component to a depleted MORB mantle composition. However, individual volcanic centres (e.g. Bakening volcano) show correlations between melt inclusion B and other geochemical indicators (e.g. Cl/K2O, Ce/B) that require mixing between isotopically distinct melt batches that have undergone different extents of crustal evolution and degassing processes. Our results show that while melt inclusion volatile inventories are largely overprinted during shallower melt storage and aggregation, incompatible trace element ratios and B isotope compositions more faithfully trace initial mantle compositions and subduction inputs. Furthermore, we suggest that the signals of compositional heterogeneity generated in the sub-arc mantle by protracted metasomatism during earlier phases of subduction can be preserved during later magma assembly and storage in the crust. Article in Journal/Newspaper Kamchatka Durham University: Durham Research Online Earth and Planetary Science Letters 562 116848 |
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Durham University: Durham Research Online |
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The chemistry of primitive arc rocks provides a window into compositional variability in the mantle wedge, as well as slab-derived inputs to subduction-related magmatism. However, in the long-term cycling of elements between Earth's internal and external reservoirs, a key unknown is the importance of retaining mobile elements within the subduction system, through subduction-related metasomatism of the mantle. To address these questions, we have analysed olivine-hosted melt inclusions and corresponding bulk rocks from the Kamchatka arc. Suites of melt inclusions record evidence for entrapment along melt mixing arrays during assembly of diverse parental magma compositions. Systematic variations in parental magma B/Zr, Nb/Zr, Ce/B, and B are also apparent among the different eruptive centres studied. These element ratios constrain the nature of subduction-related metasomatism and provide evidence for ambient mantle heterogeneity and variable degrees of mantle melting. High Nb/Zr and low B/Zr in back-arc rocks indicate smaller degree melts, lower slab-derived inputs, but relatively enriched mantle compositions. Similarly, small monogenetic eruptive centres located away from the main stratocones also tend to erupt magmas with relatively lower slab contribution and overall smaller melting degrees. Conversely, arc-front compositions reflect greater slab contributions and larger degree melts of a more depleted ambient mantle. Across-arc variations in B (ranging from ca. ‰ in the rear-arc and Sredinny Ridge to ‰ in the Central Kamchatka Depression) are generally consistent with variable addition of an isotopically heavy slab-derived component to a depleted MORB mantle composition. However, individual volcanic centres (e.g. Bakening volcano) show correlations between melt inclusion B and other geochemical indicators (e.g. Cl/K2O, Ce/B) that require mixing between isotopically distinct melt batches that have undergone different extents of crustal evolution and degassing processes. Our results show that while melt inclusion volatile inventories are largely overprinted during shallower melt storage and aggregation, incompatible trace element ratios and B isotope compositions more faithfully trace initial mantle compositions and subduction inputs. Furthermore, we suggest that the signals of compositional heterogeneity generated in the sub-arc mantle by protracted metasomatism during earlier phases of subduction can be preserved during later magma assembly and storage in the crust. |
format |
Article in Journal/Newspaper |
author |
Iveson, Alexander A. Humphreys, Madeleine C.S. Savov, Ivan P. de Hoog, Jan C.M. Turner, Stephen J. Churikova, Tatiana G. Macpherson, Colin. G. Mather, Tamsin A. Gordeychik, Boris N. Tomanikova, Lubomira Agostini, Samuele Hammond, Keiji Pyle, David M. Cooper, George F. |
spellingShingle |
Iveson, Alexander A. Humphreys, Madeleine C.S. Savov, Ivan P. de Hoog, Jan C.M. Turner, Stephen J. Churikova, Tatiana G. Macpherson, Colin. G. Mather, Tamsin A. Gordeychik, Boris N. Tomanikova, Lubomira Agostini, Samuele Hammond, Keiji Pyle, David M. Cooper, George F. Deciphering variable mantle sources and hydrous inputs to arc magmas in Kamchatka |
author_facet |
Iveson, Alexander A. Humphreys, Madeleine C.S. Savov, Ivan P. de Hoog, Jan C.M. Turner, Stephen J. Churikova, Tatiana G. Macpherson, Colin. G. Mather, Tamsin A. Gordeychik, Boris N. Tomanikova, Lubomira Agostini, Samuele Hammond, Keiji Pyle, David M. Cooper, George F. |
author_sort |
Iveson, Alexander A. |
title |
Deciphering variable mantle sources and hydrous inputs to arc magmas in Kamchatka |
title_short |
Deciphering variable mantle sources and hydrous inputs to arc magmas in Kamchatka |
title_full |
Deciphering variable mantle sources and hydrous inputs to arc magmas in Kamchatka |
title_fullStr |
Deciphering variable mantle sources and hydrous inputs to arc magmas in Kamchatka |
title_full_unstemmed |
Deciphering variable mantle sources and hydrous inputs to arc magmas in Kamchatka |
title_sort |
deciphering variable mantle sources and hydrous inputs to arc magmas in kamchatka |
publisher |
Elsevier |
publishDate |
2021 |
url |
http://dro.dur.ac.uk/32658/ http://dro.dur.ac.uk/32658/1/32658.pdf https://doi.org/10.1016/j.epsl.2021.116848 |
genre |
Kamchatka |
genre_facet |
Kamchatka |
op_source |
Earth and planetary science letters, 2021, Vol.562 [Peer Reviewed Journal] |
op_relation |
dro:32658 issn:0012-821X doi:10.1016/j.epsl.2021.116848 http://dro.dur.ac.uk/32658/ https://doi.org/10.1016/j.epsl.2021.116848 http://dro.dur.ac.uk/32658/1/32658.pdf |
op_rights |
©2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1016/j.epsl.2021.116848 |
container_title |
Earth and Planetary Science Letters |
container_volume |
562 |
container_start_page |
116848 |
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1766051082281156608 |