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The importance of water to oceanic mantle melting regimes

Nature volume 421, pages 815820 (20 February 2003) | Download Citation

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Abstract

The formation of basaltic crust at mid-ocean ridges and ocean islands provides a window into the compositional and thermal state of the Earth's upper mantle. But the interpretation of geochemical and crustal-thickness data in terms of magma source parameters depends on our understanding of the melting, melt-extraction and differentiation processes that intervene between the magma source and the crust. Much of the quantitative theory developed to model these processes has neglected the role of water in the mantle and in magma, despite the observed presence of water in ocean-floor basalts. Here we extend two quantitative models of ridge melting, mixing and fractionation to show that the addition of water can cause an increase in total melt production and crustal thickness while causing a decrease in mean extent of melting. This may help to resolve several enigmatic observations in the major- and trace-element chemistry of both normal and hotspot-affected ridge basalts.

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Acknowledgements

We thank P. Michael for comments and suggestions. This work was supported by the National Science Foundation.

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Affiliations

  1. *Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA

    • P. D. Asimow
  2. †Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, USA

    • C. H. Langmuir

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The authors declare that they have no competing financial interests.

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Correspondence to P. D. Asimow.

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https://doi.org/10.1038/nature01429

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