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Transient high temperatures in mantle plume heads inferred from magnesian olivines in Phanerozoic picrites

Nature volume 407, pages 502506 (28 September 2000) | Download Citation

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Abstract

Both scaled laboratory experiments and numerical models of terrestrial mantle plumes produce ‘balloon-on-a-string’ structures, with a bulbous head followed by a stem-like tail. Discussions have focused on whether their initial upwelling heads are hotter than the tails or cooler, as a result of entrainment of ambient mantle during ascent1,2,3, and also on whether initial plume upwelling is a newtonian or non-newtonian process4,5. The temperature of the mantle delivered to the base of the lithosphere is a critical parameter in such debates. Dry continental magmas can normally contribute little to this topic because their hottest (ultramafic) examples can be expected to be trapped, owing to their density, beneath the Moho. Here we report a rare case in which olivine (with 93.3% forsterite; Mg2SiO 4) phenocrysts, precipitated from an unerupted komatiitic melt (24% MgO) of the Tristan mantle plume head 132 Myr ago, were carried to upper-crust levels in northwest Namibia by less Mg-rich (9.6–18.5% MgO) magmas. We infer that the hidden melt, generated when the plume impinged on the base of the lithosphere, originated in the mantle with a potential temperature of 1,700 °C. This is 400 °C above ambient and much hotter than the temperatures previously calculated for steady-state Phanerozoic mantle plumes3,6,7,8. Published data show that the same conclusion can be reached for the initial Iceland and Galapagos plumes.

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References

  1. 1.

    & Stirring and structure in mantle starting plumes. Earth Planet. Sci. Lett. 99, 66–78 (1990).

  2. 2.

    & Numerical investigation of the mantle plume initiation model for flood basalt events. J. Geophys. Res. 99, 13813–13833 ( 1994); Thermal entrainment and melting in mantle plumes. Earth Planet. Sci. Lett. 136, 251– 267 (1995).

  3. 3.

    & Mantle plumes and flood basalts. J. Geophys. Res. 100, 17543– 17585 (1995).

  4. 4.

    Evolution of starting mantle plumes: a comparison between numerical and laboratory models. Earth Planet. Sci. Lett. 148, 1– 11 (1997).

  5. 5.

    , & Ultrafast mantle plumes and implications for flood basalt volcanism in the North Atlantic Region. Tectonophysics 311, 31–43 (1999).

  6. 6.

    & Melt generation by plumes: a study of Hawaiian volcanism. J. Petrol. 32, 501 –537 (1991).

  7. 7.

    & The dynamical origin of Hawaiian volcanism. Earth Planet. Sci. Lett. 171, 517–531 (1999).

  8. 8.

    , , & Seismic evidence for a lower-mantle origin of the Icelandic plume. Nature 395, 62–65 ( 1998).

  9. 9.

    & The volume and composition of melt generated by extension of the lithosphere. J. Petrol. 29, 625–679 (1988).

  10. 10.

    , & in Magmatism and the Causes of Continental Break-up (eds Storey, B. C., Alabaster, T. & Pankhurst, R. J.) 335 –348 (Spec. Publ. 68, Geological Society, London, 1992).

  11. 11.

    , , & Constraining the potential temperature of the Archaean mantle: a review of the evidence from komatiites. Lithos 30, 291–307 (1993).

  12. 12.

    & Pyroclastic rocks: another manifestation of ultramafic volcanism on Gorgona island, Colombia. Contrib. Mineral. Petrol. 92, 428– 436 (1986).

  13. 13.

    The Baffin Bay lavas and the value of picrites as analogues of primary magmas. Contrib. Mineral. Petrol. 89, 144– 154 (1985).

  14. 14.

    IUGS reclassification of the high-Mg and picritic volcanic rocks. J. Petrol. (in the press).

  15. 15.

    , , , & in Mafic Dykes and Emplacement Mechanisms (eds Parker, A. J., Rickwood, P. C. & Tucker, D. H.) 119–129 (Balkema, Rotterdam, 1990).

  16. 16.

    , , , & Petrogenesis and 40 Ar/39Ar geochronology of the Brandberg complex, Namibia: evidence for a major mantle contribution in metaluminous and peralkaline granites. J. Petrol. 41, 1207–1239 (2000).

  17. 17.

    Systematics of calcium partitioning between olivine and silicate melt: implications for melt structure and calcium content of magmatic olivines. Contrib. Mineral. Petrol. 136, 63–80 (1999).

  18. 18.

    , & Subsolidus phase relations in the system MgO-SiO 2-Cr-O in equilibrium with metallic Cr, and their significance for the petrochemistry of chromium. J. Petrol. 36, 107–132 (1995).

  19. 19.

    The dependence of the Fe2+-Mg cation-partitioning between olivine and basaltic liquid on pressure, temperature and composition. Contrib. Mineral. Petrol. 101, 261– 273 (1989).

  20. 20.

    et al. South Atlantic volcanic margins. J. Geol. Soc. Lond. 154, 465–470 ( 1997).

  21. 21.

    in Evolution of the Damara Orogen of South West Africa/Namibia (ed. Miller, R. McG.) 431–515 (Spec. Publ. 11, Geological Society of South Africa, 1983).

  22. 22.

    , & in Mauna Loa Revealed: Structure, Composition, History and Hazards (eds Rhodes, J. M. & Lockwood, J. P.) 219– 239 (Geophys. Monogr. 92, American Geophysical Union, Washington DC, 1995).

  23. 23.

    , & in Mauna Loa Revealed: Structure, Composition, History and Hazards (eds Rhodes, J. M. & Lockwood, J. P.) 207– 217 (Geophys. Monogr. 92, American Geophysical Union, Washington DC, 1995).

  24. 24.

    , , & Two mantle sources, two plumbing systems; tholeiitic and alkaline magmatism of the Maymecha River basin, Siberian flood volcanic province. Contrib. Mineral. Petrol. 133, 297– 313 (1998).

  25. 25.

    , , & Melting study of a peridotite KLB-1 to 6.5 GPa and the origin of basaltic magmas. Philos. Trans. R. Soc. Lond. A 342, 105–120 (1993).

  26. 26.

    & Melting experiments on anhydrous peridotite KLB-1: compositions of magmas in the upper mantle and transition zone. J. Geophys. Res. 101, 8271–8295 (1996).

  27. 27.

    , & Dynamic melting in plume heads: the formation of Gorgona komatiites and basalts. Earth Planet. Sci. Lett. 146 , 289–301 (1997).

  28. 28.

    , & The heterogeneous Iceland plume: new insights from the alkaline basalts of Snaefell volcanic centre. J. Geol. Soc. Lond. 152, 1003–1009 ( 1995).

  29. 29.

    Major-element variability in the Hawaiian mantle plume. Nature 382, 415–419 ( 1996).

  30. 30.

    , & Ferropicrites: geochemical evidence for Fe-rich streaks in upwelling mantle plumes. Earth Planet. Sci. Lett. 174, 355–374 (2000).

  31. 31.

    , & Volatiles in pillow rim glasses from Loihi and Kilauea volcanoes, Hawaii. Geochim. Cosmochim. Acta 49, 1887–1896 (1985).

  32. 32.

    & Chromian spinels as petrogenetic indicators: thermodynamic and petrological applications. Am. Mineral. 76, 827–847 ( 1991).

  33. 33.

    , , & Peridotite melting at 1.0 and 1.5 GPa: an experimental evaluation of techniques using diamond aggregates and mineral mixes for determination of near-solidus melts. J. Petrol. 40, 1343– 1375 (1999).

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Acknowledgements

We thank N. Arndt, M. Bickle, R. Hardy, D. Jerram, G. Milne, S. Milner, A.-K. Nguno, S. Reed, P. M. Smith and M. Tucker for assistance and discussions, and M. Garcia, R. Gill, G. Pearson and P. M. Smith for comments that substantially improved the manuscript. Durham and Cambridge universities funded the research in part.

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  1. *Department of Geological Sciences, University of Durham, South Road, Durham DH1 3LE, UK

    • R. N. Thompson
  2. †Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK

    • S. A. Gibson

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Correspondence to R. N. Thompson.

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https://doi.org/10.1038/35035058

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