Pb isotopic variability in melt inclusions from the EMI–EMII–HIMU mantle end-members and the role of the oceanic lithosphere
Abstract
Melt inclusions from four individual lava samples representing the HIMU (Mangaia Island), EMI (Pitcairn Island) and EMII (Tahaa Island) end member components, have heterogeneous Pb isotopic composition larger than that defined by the erupted lavas in each island. The broad linear trend in ^(207)Pb/^(206)Pb–^(208)Pb/^(206)Pb space produced by the melt inclusions from Mangaia, Tahaa and fPitcairn samples reproduces the entire trend defined by the Austral chain, the Society islands and the Pitcairn island and seamount groups. The inclusions preserve a record of melt composition of far greater isotopic diversity than that sampled in whole rock basalts. These results can be explained by mixing of a common depleted component with the HIMU, EMI and EMII lavas, respectively. We favor a model that considers the oceanic lithosphere to be that common component. We suggest that the Pb isotopic compositions of the melt inclusions reflect wall rock reaction of HIMU, EMI and EMII melts during their percolation through the oceanic lithosphere. Under these conditions, the localized rapid crystallization of olivine from primitive basalt near the reaction zone would allow the entrapment of melt inclusions with different isotopic composition.
Additional Information
© 2005 Elsevier B.V. Received 24 April 2005; received in revised form 1 October 2005; accepted 4 October 2005. Available online 10 November 2005. Editor: K. Farley. We are grateful to M. O. Garcia for the Loihi sample that we used as standards during this work, to K. Farley and H. Craig for providing the Pitcairn sample, and to E. Drenkard for the reading the manuscript. Thorough and constructive reviews by R. Nielsen and I. VlastÈlic are also greatly appreciated. All the authors are deeply grateful for the support received from NSF.Attached Files
Supplemental Material - mmc1.pdf
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- CaltechAUTHORS:20121030-090706151
- NSF
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2012-10-30Created from EPrint's datestamp field
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2021-11-09Created from EPrint's last_modified field
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- Division of Geological and Planetary Sciences