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Oxygen-isotope and trace element constraints on the origins of silica-rich melts in the subarc mantle

Eiler, J. M. and Schiano, P. and Valley, J. W. and Kita, N. T. and Stolper, E. M. (2007) Oxygen-isotope and trace element constraints on the origins of silica-rich melts in the subarc mantle. Geochemistry, Geophysics, Geosystems, 8 (9). 2006GC001503. ISSN 1525-2027. https://resolver.caltech.edu/CaltechAUTHORS:EILggg07

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[img] Plain Text (Table S1 major element and oxygen-isotope compositions of materials used to standardize ion-microprobe analyses) - Supplemental Material
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[img] Plain Text (Table S2 Individual SIMS analyses of δ18O in oxygen isotope standards, organized by sample holder and standard.) - Supplemental Material
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[img] Plain Text (Table S3 Electron microprobe analyses of major and minor element compositions of glass inclusions in Batan xenoliths.) - Supplemental Material
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[img] Plain Text (Table S4 Oxygen isotope analyses of sample and standard materials mounted together in sample B3N, reported in the “WiscSIMS” format.) - Supplemental Material
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[img] Plain Text (Table S5 Trace element compositions of assumed model sources.) - Supplemental Material
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[img] Plain Text (Table S6 Distribution coefficients between bulk eclogite and silicate melt.) - Supplemental Material
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[img] Plain Text (Table S7 Distribution coefficients between bulk eclogite or peridotite and aqueous fluid.) - Supplemental Material
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[img] Plain Text (Table S8 Distribution coefficients between bulk ultra-depleted peridotite and silicate melt, based on mineral/melt D's given in Eiler et al. [2005].) - Supplemental Material
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Abstract

Peridotitic xenoliths in basaltic andesites from Batan island in the Luzon arc contain silica-rich (broadly dacitic) hydrous melt inclusions that were likely trapped when these rocks were within the upper mantle wedge underlying the arc. These melt inclusions have been previously interpreted to be slab-derived melts. We tested this hypothesis by analyzing the oxygen isotope compositions of these inclusions with an ion microprobe. The melt inclusions from Batan xenoliths have δ 18OVSMOW values of 6.45 ± 0.51‰. These values are consistent with the melts having been in oxygen isotope exchange equilibrium with average mantle peridotite at temperatures of ≥875°C. We suggest the δ 18O values of Batan inclusions, as well as their major and trace element compositions, can be explained if they are low-degree melts (or differentiation products of such melts) of peridotites in the mantle wedge that had previously undergone extensive melt extraction followed by metasomatism by small amounts (several percent or less) of slab-derived components. A model based on the trace element contents of Batan inclusions suggests that this metasomatic agent was an aqueous fluid extracted from subducted basalts and had many characteristics similar to slab-derived components of the sources of arc-related basalts at Batan and elsewhere. Batan inclusions bear similarities to “adakites,” a class of arc-related lava widely considered to be slab-derived melts. Our results suggest the alternative interpretation that at least some adakite-like liquids might be generated from low-degree melting of metasomatized peridotites.


Item Type:Article
ORCID:
AuthorORCID
Stolper, E. M.0000-0001-8008-8804
Additional Information:© 2007 American Geophysical Union. Received 9 October 2006; accepted 19 June 2007; published 21 September 2007. We thank Rene Maury for providing access to the sample examined in this study and for his help and guidance during the early stages of this work. This study benefited from financial support from NSF grant EAR-0337736 and a grant to J.M.E. from the Packard foundation. This work benefited from reviews by P. Kelemen, C. Macpherson, J. Ryan, and G. Gaetani. We thank G. Bebout and V. Salters for their work editing this paper. Auxiliary material for this article contains two sections: (1) the methods of standardization and raw data for ion microprobe analyses of oxygen isotope ratios in minerals and glasses examined in this study and (2) the distribution coefficients and source compositions used in trace element models.
Funders:
Funding AgencyGrant Number
NSFEAR-0337736
David and Lucile Packard FoundationUNSPECIFIED
Subject Keywords:subduction zone; slab melting; oxygen isotopes; adakites
Issue or Number:9
Record Number:CaltechAUTHORS:EILggg07
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:EILggg07
Alternative URL:http://dx.doi.org/10.1029/2006GC001503.
Official Citation:Eiler, J. M., P. Schiano, J. W. Valley, N. T. Kita, and E. M. Stolper (2007), Oxygen-isotope and trace element constraints on the origins of silica-rich melts in the subarc mantle, Geochem. Geophys. Geosyst., 8, Q09012, doi:10.1029/2006GC001503.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9087
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:26 Oct 2007
Last Modified:02 Oct 2019 23:57

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