Eiler, John M. and Farley, Kenneth A. and Valley, John W. and Stolper, Edward M. and Haurl, Eric H. and Craig, Harmon (1995) Oxygen isotope evidence against bulk recycled sediment in the mantle sources of Pitcairn Island lavas. Nature, 377 (6545). pp. 138-141. ISSN 0028-0836 http://resolver.caltech.edu/CaltechAUTHORS:20120827-082431654
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The hypothesis that subducted sediments survive dehydration and/or melting in subduction zones to become long-lived geo-chemical reservoirs in the mantle has gained support in recent years. Evidence for such reservoirs is found in the geochemistry of ocean island basalts (OIBs), some of which have isotopic and trace-element characteristics plausibly associated with ancient sedimentary components. In particular, the EM1 mantle end-member has been identified, principally on the basis of strontium, neodymium and lead isotopes, and has been proposed to carry a large sediment fraction. Oxygen isotopes should be sensitive indicators of subducted sediment in the sources of OIBs because minerals that interact with water at low temperatures near the Earth's surface (during weathering, for example) become enriched in ^(18)O relative to ^(16)O (ref. 6). We report here the ^(18)O:^(16)O ratios of phenocrysts from basalts from Pitcairn Island (southeast Pacific Ocean), which, together with the nearby Pitcairn seamounts, contain among the most extreme EM1 signatures known. We find the oxygen isotope ratios of the phenocrysts to be indistinguishable from the average for mantle peridotite. These results show that the end-member EM1 signature can be produced in the absence of substantial (>l-2%) recycled sediment in the mantle.
|Additional Information:||© 1995 Nature Publishing Group. Received 10 April; accepted 8 August 1995. We thank J. Woodhead for sharing unpublished analysis of seamount glasses, W. White for comments on the manuscript, M. Spicuzza and N. Kitchen for assistance in the stable-isotope laboratory, and P. Carpenter for help with electron microprobe analysis. This research was supported in part by DOE and NSF.|
|Official Citation:||Oxygen isotope evidence against bulk recycled sediment in the mantle sources of Pitcairn Island lavas 138 John M. Eiler, Kenneth A. Farley, John W. Valley, Edward M. Stolper, Eric H. Hauri & Harmon Craig doi:10.1038/377138a0|
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|Deposited By:||Ruth Sustaita|
|Deposited On:||27 Aug 2012 15:59|
|Last Modified:||27 Aug 2012 15:59|
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