Abstract

Roughly 60% of the Earth’s outer surface is composed of oceanic crust formed by volcanic processes at mid-ocean ridges. Although only a small fraction of this vast volcanic terrain has been visually surveyed or sampled, the available evidence suggests that explosive eruptions are rare on mid-ocean ridges, particularly at depths below the critical point for seawater (3,000 m)1. A pyroclastic deposit has never been observed on the sea floor below 3,000 m, presumably because the volatile content of mid-ocean-ridge basalts is generally too low to produce the gas fractions required for fragmenting a magma at such high hydrostatic pressure. We employed new deep submergence technologies during an International Polar Year expedition to the Gakkel ridge in the Arctic Basin at 85° E, to acquire photographic and video images of ‘zero-age’ volcanic terrain on this remote, ice-covered ridge. Here we present images revealing that the axial valley at 4,000 m water depth is blanketed with unconsolidated pyroclastic deposits, including bubble wall fragments (limu o Pele)2, covering a large (>10 km2) area. At least 13.5 wt% CO2 is necessary to fragment magma at these depths3, which is about tenfold the highest values previously measured in a mid-ocean-ridge basalt4. These observations raise important questions about the accumulation and discharge of magmatic volatiles at ultraslow spreading rates on the Gakkel ridge5 and demonstrate that large-scale pyroclastic activity is possible along even the deepest portions of the global mid-ocean ridge volcanic system.

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References

  1. 1.

    , & in Explosive Subaqueous Volcanism (eds White, J. D. L., Smellie, J. L. & Clague, D. A.) 1–24 (American Geophysical Union, Washington DC, 2003)

  2. 2.

    , & Limu o Pele: A new kind of hydroclastic tephra from Kilauea Volcano. Hawai’i Geol. Soc. Am. Abst. Prog. 20, A112–A113 (1988)

  3. 3.

    & Deep submarine pyroclastic eruptions: theory and predicted landforms and deposits. J. Volcanol. Geotherm. Res. 121, 155–193 (2003)

  4. 4.

    & The volatiles record of a ‘popping’ rock from the Mid-Atlantic Ridge at 14°N: Chemical and isotopic composition of gas trapped in the vesicles. Earth Planet. Sci. Lett. 107, 598–611 (1991)

  5. 5.

    , & REVEL: A model for recent plate velocities from space geodesy. J. Geophys. Res. 107 10.1029/2000JB000033 (2002)

  6. 6.

    & Seismic evidence for volcanic activity discovered in central Arctic. Eos 81, 265–269 (2000)

  7. 7.

    , , & Seismic character of volcanic activity at the ultraslow-spreading Gakkel Ridge. Geology 29, 1139–1142 (2001)

  8. 8.

    et al. Evidence of recent volcanic activity on the ultraslow-spreading Gakkel ridge. Nature 409, 808–812 (2001)

  9. 9.

    et al. Discovery of abundant hydrothermal venting on the ultraslow-spreading Gakkel ridge in the Arctic Ocean. Nature 421, 252–256 (2003)

  10. 10.

    et al. Helium-3, methane, and manganese in water column hydrothermal plumes along the ultra-slow spreading Gakkel Ridge, Arctic Ocean. Ofioliti 31, 234–235 (2006)

  11. 11.

    , , , & Lava bubble-wall fragments formed by submarine hydrovolcanic explosions on Loihi Seamount and Kilauea Volcano. Volcano Bull. Volcanol. 61, 437–449 (2000)

  12. 12.

    , , & in Explosive Subaqueous Volcanism (eds White, J. D. L., Smellie, J. L. & Clague, D. A.) 143–166 (American Geophysical Union, Washington DC, 2003)

  13. 13.

    et al. Extensive volcaniclastic deposits at the Mid-Atlantic Ridge axis; results of deep-water basaltic explosive volcanic activity? Terra Nova 10, 280–286 (1998)

  14. 14.

    et al. Deep sea explosive activity on the Mid-Atlantic Ridge near 34° 50′ N: Magma composition, vesicularity, and volatile content. J. Volcanol. Geotherm. Res. 98, 49–77 (2000)

  15. 15.

    , & in Explosive Subaqueous Volcanism (eds White, J. D. L., Smellie, J. L. & Clague, D. A.) 111–128 (American Geophysical Union, Washington DC, 2003)

  16. 16.

    , , & in Hawaiian Volcanoes: Deep Underwater Perspectives (eds Takahashi, E., Lipman, P. W., Garcia, M. O., Naka, J. & Aramaki, S.) 65–84 (American Geophysical Union, Washington DC, 2002)

  17. 17.

    The dynamics of bubble formation and growth in magmas: A review and analysis. J. Volcanol. Geotherm. Res. 3, 1–37 (1978)

  18. 18.

    & Mid-ocean ridge basalt degassing: Bubble nucleation. J. Geophys. Res. 95, 5125–5131 (1990)

  19. 19.

    , & Seismoacoustic evidence for volcanic activity on the ultraslow-spreading Gakkel Ridge, Arctic Ocean. Geophys. Res. Lett. 32 10.1029/2005GL023767 (2005)

  20. 20.

    , & An ultraslow-spreading class of ocean ridge. Nature 426, 405–412 (2003)

  21. 21.

    et al. Magmatism and amagmatic seafloor generation at the ultraslow-spreading Gakkel ridge, Arctic Ocean. Nature 423, 956–961 (2003)

  22. 22.

    & Free software helps map and display data. Eos 72, 441 (1991)

  23. 23.

    et al. Biological and geological characteristics of the Gakkel Ridge. Eos 88, abstr. OS41C–08 (2007)

Download references

Acknowledgements

We thank D. Clague and J. Head for reviews that improved the final manuscript, the Advanced Imaging Laboratory at WHOI for technical support and the crew of icebreaker Oden for technical support at sea. This research was funded by the National Aeronautics and Space Administration, the National Science Foundation, and the Woods Hole Oceanographic Institution.

Author Contributions R.A.S. was the chief scientist of the Arctic Gakkel Vents Expedition and wrote the paper. H.S., T.M.S, S.H. and C.W. collected the dive imagery. T.M.S., S.H., C.W. and A.S. analysed the dive imagery. M.J. processed the bathymetric data. H.N.E., C.K., U.H., E.H., M.J., B.L., J.L., C.M., K.N., T.S., V.S, C.S., M.T., L.U. and P.W. provided technical and scientific support at sea. All authors discussed the results and provided input to the manuscript.

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  1. Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA

    • Robert A. Sohn
    • , Claire Willis
    • , Susan Humphris
    • , Timothy M. Shank
    • , Hanumant Singh
    • , Clayton Kunz
    • , Christopher Murphy
    • , Peter Winsor
    •  & Adam Soule
  2. Marine Science Institute, University of Texas at Austin, Port Aransas, Texas 78373, USA

    • Henrietta N. Edmonds
    •  & Lucia Upchurch
  3. Swedish Polar Secretariat, 104 05 Stockholm, Sweden

    • Ulf Hedman
  4. Alfred Wegener Institute for Polar and Marine Research, Bremerhaven 27570, Germany

    • Elisabeth Helmke
    • , Julia Linder
    • , Vera Schlindwein
    •  & Maria Tausenfreund
  5. Johns Hopkins University, Baltimore, Maryland 21218, USA

    • Michael Jakuba
  6. Göteborg University, Goteborg 40530, Sweden

    • Bengt Liljebladh
    •  & Christian Stranne
  7. AIST, Tsukuba Central 7, 1-1-1 Higashi, Japan

    • Ko-ichi Nakamura
  8. Ocean Research Institute, University of Tokyo, Minamidai, Nakano, Tokyo 164-8639, Japan

    • Taichi Sato
  9. Department of Geology and Geochemistry, Stockholm University, 106 91 Stockholm, Sweden

    • Martin Jakobsson

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Correspondence to Robert A. Sohn.

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https://doi.org/10.1038/nature07075

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