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Oxygen isotopes in Samoan lavas: Confirmation of continent recycling

Workman, Rhea K. and Eiler, John M. and Hart, Stanley R. and Jackson, Matthew G. (2008) Oxygen isotopes in Samoan lavas: Confirmation of continent recycling. Geology, 36 (7). pp. 551-554. ISSN 0091-7613. https://resolver.caltech.edu/CaltechAUTHORS:20121114-155452022

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Abstract

Lavas from the Samoan volcanic chain show the most enriched geochemical signatures ever documented in oceanic lavas (^(87)Sr/^(86)Sr as high as 0.7205). In order to test the hypothesis that their source contains a component of recycled upper continental crust, we measured oxygen isotope compositions of olivine phenocrysts from these lavas. Correlations between δ^(18)O of olivines (5.11‰–5.70‰) and ^(87)Sr/^(86)Sr and ^(207)Pb/^(204)Pb of whole rocks, as well as Ce/Pb and Nb/Th ratios of whole rocks, indicate that (1) measured δ^(18)O are primary, mantle-derived values, and (2) the enriched mantle source of these lavas contains continental crust or its derivative sediments. The observed trend between δ^(18)O and ^(87)Sr/^(86)Sr can be fit using either clastic marine sediment or continental crust values of δ^(18)O, Sr concentration, and ^(87)Sr/^(86)Sr, but only those for clastic marine sediments are compatible with trace element modeling. We conclude that the enriched source for Samoan basalts was created by sedimentation of continent-derived material into a marine environment, followed by subduction and mixing with ambient mantle.


Item Type:Article
Related URLs:
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http://dx.doi.org/10.1130/G24558A.1DOIUNSPECIFIED
http://geology.gsapubs.org/content/36/7/551PublisherUNSPECIFIED
http://geology.geoscienceworld.org/content/36/7/551PublisherUNSPECIFIED
Additional Information:© 2008 The Geological Society of America. Manuscript received 7 November 2007. Revised manuscript received 1 April 2008. Manuscript accepted 4 April 2008. We thank Nami Kitchen for her skilled help on the laser fluorination apparatus. We also thank E. Widom, P. Castillo, and W. White for their thoughtful reviews of this manuscript. We gratefully acknowledge National Science Foundation grants OCE-9819038 and EAR-0125917 (to Hart).
Funders:
Funding AgencyGrant Number
NSFOCE-9819038
NSFEAR-0125917
Subject Keywords:oxygen isotopes, Samoa, enriched mantle, EM2, ocean island basalts
Issue or Number:7
Record Number:CaltechAUTHORS:20121114-155452022
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20121114-155452022
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:35466
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:16 Nov 2012 22:37
Last Modified:03 Oct 2019 04:28

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