Chemical and isotopic changes induced by pyrometamorphism in metasedimentary xenoliths at Tongariro volcano, New Zealand

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dc.contributor.author Pure, Leo R.
dc.contributor.author Charlier, Bruce L. A.
dc.contributor.author Wilson, Colin J. N.
dc.contributor.author Gamble, John A.
dc.contributor.author Vry, Julie K.
dc.contributor.author Townsend, Dougal B.
dc.contributor.author Leonard, Graham S.
dc.date.accessioned 2021-08-12T11:15:17Z
dc.date.available 2021-08-12T11:15:17Z
dc.date.issued 2021-08-04
dc.identifier.citation Pure, L. R., Charlier, B. L. A., Wilson, C. J. N., Gamble, J. A., Vry, J. K., Townsend, D. B. and Leonard, G. S. (2021) 'Chemical and isotopic changes induced by pyrometamorphism in metasedimentary xenoliths at Tongariro volcano, New Zealand', Lithos, 106404. doi: 10.1016/j.lithos.2021.106404 en
dc.identifier.issn 0024-4937
dc.identifier.uri http://hdl.handle.net/10468/11734
dc.identifier.doi 10.1016/j.lithos.2021.106404 en
dc.description.abstract Andesites erupted from Tongariro volcano, North Island, New Zealand contain feldspathic and quartzose xenoliths derived from basement rocks. New major oxide, trace element and Sr-Nd-Pb isotopic data indicate that both the Waipapa and Kaweka (meta)sedimentary terranes are represented in erupted xenoliths, rather than only the Kaweka terrane as previously thought. Xenolith mineral assemblages differ from their likely source materials, notably through the lack of white mica, illite, chlorite and quartz, which is reflected in contrasting chemical and isotopic compositions. Major and trace element data indicate that most xenoliths underwent bulk mass decreases of about 50% when pyrometamorphosed at temperatures of ~800–980 °C, similar to typical Tongariro magma temperatures of ~800–1000 °C. Bulk Eu concentrations were retained (in restitic plagioclase); however, other rare earth elements are commonly lower in xenoliths than in protoliths. In xenoliths, the 143Nd/144Nd ratios of protoliths were also retained, which indicates that xenoliths were derived from the Kaweka and Waipapa terranes in subequal amounts. Reductions in 87Sr/86Sr ratios by up to 0.003 in xenoliths, relative to their likely protoliths, were accompanied by decreases in Rb/Sr ratios from 0.1–0.8 down to <0.1, reflecting the dissolution of hydrous, Rb-rich minerals (white mica ± illite) with their radiogenic isotopic ingrowths liberated into surrounding andesitic magmas. Varied amounts of U/Pb, Th/Pb and Th/U fractionation demonstrably occurred between xenoliths and protoliths, but these are challenging to correlate with Pb isotopic fractionation that also occurred. One xenolith contains a vein of clinopyroxene, calcic plagioclase, silicic glass and graphite that formed when quartz + calcite veins were pyrometamorphosed. The vein-bearing xenolith possesses unusual chemical and isotopic features, which include a negative Ce anomaly, LaN/YbN ~ 2 and high 143Nd/144Nd (0.51284), which are also reported for xenolithic material erupted at neighbouring Ruapehu volcano. en
dc.description.sponsorship Victoria University of Wellington (PhD Scholarship); Ministry of Business, Innovation and Employment, New Zealand (ECLIPSE Programme); Earthquake Commission of New Zealand (grant 16/U735) en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher Elsevier B.V. en
dc.rights © 2021, Elsevier B.V. All rights reserved. This manuscript version is made available under the CC BY-NC-ND 4.0 license. en
dc.rights.uri https://creativecommons.org/licenses/by-nc-nd/4.0/ en
dc.subject Fractionation en
dc.subject Metasedimentary en
dc.subject Pyrometamorphism en
dc.subject Andesite en
dc.subject Restite en
dc.subject Xenolith en
dc.title Chemical and isotopic changes induced by pyrometamorphism in metasedimentary xenoliths at Tongariro volcano, New Zealand en
dc.type Article (peer-reviewed) en
dc.internal.authorcontactother John Gamble, Biological, Earth & Environmental Sciences, University College Cork, Cork, Ireland. +353-21-490-3000 Email: john.gamble@vuw.ac.nz en
dc.internal.availability Full text available en
dc.check.info Access to this article is restricted until 12 months after publication by request of the publisher. en
dc.check.date 2022-08-04
dc.date.updated 2021-08-12T10:43:24Z
dc.description.version Accepted Version en
dc.internal.rssid 577737674
dc.contributor.funder Victoria University of Wellington en
dc.contributor.funder Ministry of Business, Innovation and Employment en
dc.contributor.funder GNS Science, New Zealand en
dc.contributor.funder Earthquake Commission of New Zealand en
dc.description.status Peer reviewed en
dc.identifier.journaltitle Lithos en
dc.internal.copyrightchecked Yes
dc.internal.licenseacceptance Yes en
dc.internal.IRISemailaddress john.gamble@vuw.ac.nz en
dc.identifier.articleid 106404 en
dc.internal.bibliocheck In press. Check vol / issue / page range. Amend citation as necessary. en


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© 2021, Elsevier B.V. All rights reserved. This manuscript version is made available under the CC BY-NC-ND 4.0 license. Except where otherwise noted, this item's license is described as © 2021, Elsevier B.V. All rights reserved. This manuscript version is made available under the CC BY-NC-ND 4.0 license.
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