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Seismic reflection images of a near-axis melt sill within the lower crust at the Juan de Fuca ridge


The oceanic crust extends over two-thirds of the Earth’s solid surface, and is generated along mid-ocean ridges from melts derived from the upwelling mantle1. The upper and middle crust are constructed by dyking and sea-floor eruptions originating from magma accumulated in mid-crustal lenses at the spreading axis2,3,4,5,6, but the style of accretion of the lower oceanic crust is actively debated7. Models based on geological and petrological data from ophiolites propose that the lower oceanic crust is accreted from melt sills intruded at multiple levels between the Moho transition zone (MTZ) and the mid-crustal lens8,9,10,11, consistent with geophysical studies that suggest the presence of melt within the lower crust12,13,14,15,16. However, seismic images of molten sills within the lower crust have been elusive. Until now, only seismic reflections from mid-crustal melt lenses2,17,18 and sills within the MTZ have been described19, suggesting that melt is efficiently transported through the lower crust. Here we report deep crustal seismic reflections off the southern Juan de Fuca ridge that we interpret as originating from a molten sill at present accreting the lower oceanic crust. The sill sits 5–6 km beneath the sea floor and 850–900 m above the MTZ, and is located 1.4–3.2 km off the spreading axis. Our results provide evidence for the existence of low-permeability barriers to melt migration within the lower section of modern oceanic crust forming at intermediate-to-fast spreading rates, as inferred from ophiolite studies9,10.

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Figure 1: Seismic reflection profiles located over a bathymetric map of the Cleft segment of the southern JdFR.
Figure 2: Migrated seismic reflection profiles 40 and 75.
Figure 3: Observed and modelled reflection amplitudes and travel times.
Figure 4: Three-dimensional perspective of crustal structure and sea-floor topography.


  1. Forsyth, D. W. in Mantle Flow and Melt Generation at Mid-Ocean Ridges (eds Phipps Morgan, J., Blackman, D. K. & Sinton, J. M.) 1–65 (Geophysical Monograph Series Vol. 71, AGU, 1992)

    Google Scholar 

  2. Detrick, R. S. et al. Multi-channel seismic imaging of a crustal magma chamber along the East Pacific Rise. Nature 326, 35–41 (1987)

    Article  ADS  Google Scholar 

  3. Herron, T. J. et al. Structure of the East Pacific Rise crest from multichannel seismic reflection data. J. Geophys. Res. 83, 798–804 (1978)

    Article  ADS  Google Scholar 

  4. Karson, J. A. Geologic structure of the uppermost oceanic crust created at fast- to intermediate-rate spreading centers. Annu. Rev. Earth Planet. Sci. 30, 347–384 (2002)

    Article  ADS  CAS  Google Scholar 

  5. Perfit, M. R. & Chadwick, W. W. in Faulting and Magmatism at Mid-Ocean Ridges (eds Buck, W. R. et al.) 59–115 (Geophysical Monograph Series Vol. 106, AGU, 1998)

    Google Scholar 

  6. Sinton, J. M. & Detrick, R. S. Mid-ocean ridge magma chambers. J. Geophys. Res. 97, 197–216 (1992)

    Article  ADS  CAS  Google Scholar 

  7. Maclennan, J., Hulme, T. & Singh, S. C. Thermal models of oceanic crustal accretion: linking geophysical, geological and petrological observations. Geochem. Geophys. Geosyst. 5 Q02F25 10.1029/2003GC000605 (2004)

    Article  CAS  Google Scholar 

  8. Kelemen, P. B., Koga, K. & Shimizu, N. Geochemistry of gabbro sills in the crust-mantle transition zone of the Oman ophiolite: implications for the origin of the oceanic lower crust. Earth Planet. Sci. Lett. 146, 475–488 (1997)

    Article  ADS  CAS  Google Scholar 

  9. Boudier, F., Nicolas, A. & Ildefonse, B. Magma chambers in the Oman ophiolite: fed from the top and the bottom. Earth Planet. Sci. Lett. 144, 239–250 (1996)

    Article  ADS  CAS  Google Scholar 

  10. Kelemen, P. B. & Aharonov, E. in Faulting and Magmatism at Mid-Ocean Ridges (eds Buck, W. R. et al.) 267–289 (Geophysical Monograph Series Vol. 106, AGU, 1998)

    Google Scholar 

  11. Korenaga, J. & Kelemen, P. B. Origin of gabbro sills in the Moho transition zone of the Oman ophiolite: implications for magma transport in the oceanic lower crust. J. Geophys. Res. 102, 27729–27749 (1997)

    Article  ADS  CAS  Google Scholar 

  12. Singh, S. C. et al. Seismic reflection images of the Moho underlying melt sills at the East Pacific Rise. Nature 442, 287–290 (2006)

    Article  ADS  CAS  Google Scholar 

  13. Crawford, W. C. & Webb, S. C. Variations in the distribution of magma in the lower crust and at the Moho beneath the East Pacific Rise at 9°-10°N. Earth Planet. Sci. Lett. 203, 117–130 (2002)

    Article  ADS  CAS  Google Scholar 

  14. Dunn, R. A., Toomey, D. R. & Solomon, S. C. Three-dimensional seismic structure and physical properties of the crust and shallow mantle beneath the East Pacific Rise at 9° 30'N. J. Geophys. Res. 105, 23537–23555 (2000)

    Article  ADS  Google Scholar 

  15. Garmany, J. Accumulations of melt at the base of young oceanic crust. Nature 340, 628–632 (1989)

    Article  ADS  Google Scholar 

  16. Wilcock, W. S. D., Solomon, S. C., Purdy, G. M. & Toomey, D. R. The seismic attenuation structure of a fast-spreading mid-ocean ridge. Science 258, 1470–1474 (1992)

    Article  ADS  CAS  Google Scholar 

  17. Mutter, J. C. et al. Seismic images of active magma systems beneath the East Pacific Rise between 17°05' and 17°35'S. Science 268, 391–395 (1995)

    Article  ADS  CAS  Google Scholar 

  18. Singh, S. C. et al. Melt to mush variations in crustal magma properties along the ridge crest at the southern East Pacific Rise. Nature 394, 874–878 (1998)

    Article  ADS  CAS  Google Scholar 

  19. Nedimović, M. R. et al. Frozen magma lenses below the oceanic crust. Nature 436, 1149–1152 (2005)

    Article  ADS  Google Scholar 

  20. Wilson, D. S. Confidence intervals for motion and deformation of the Juan de Fuca plate. J. Geophys. Res. 98, 16053–16071 (1993)

    Article  Google Scholar 

  21. Canales, J. P. et al. Upper crustal structure and axial topography at intermediate-spreading ridges: seismic constraints from the Southern Juan de Fuca Ridge. J. Geophys. Res. 110 B12104 10.1029/2005JB003630 (2005)

    Article  ADS  Google Scholar 

  22. Carbotte, S. M. et al. Rift topography linked to magmatism at the intermediate spreading Juan de Fuca Ridge. Geology 34, 209–212 (2006)

    Article  ADS  Google Scholar 

  23. Jousselin, D. & Nicolas, A. The Moho transition in the Oman ophiolite — relation with wehrlites in the crust and dunites in the mantle. Mar. Geophys. Res. 21, 229–241 (2000)

    Article  Google Scholar 

  24. Taylor, M. A. J. & Singh, S. C. Compositions and microstructure of magma bodies from effective medium theory. Geophys. J. Int. 149, 15–21 (2002)

    Article  ADS  Google Scholar 

  25. Aharonov, E., Whitehead, J., Kelemen, P. B. & Spiegelman, M. Channeling instability of upwelling melt in the mantle. J. Geophys. Res. 100, 20433–20450 (1995)

    Article  ADS  Google Scholar 

  26. Kelemen, P. B., Shimizu, N. & Salters, V. J. M. Extraction of mid-ocean ridge basalt from the upwelling mantle by focused flow of melt in dunite channels. Nature 375, 747–753 (1995)

    Article  ADS  CAS  Google Scholar 

  27. Korenaga, J. & Kelemen, P. B. Melt migration through the oceanic lower crust: a constraint from melt percolation modeling with finite solid diffusion. Earth Planet. Sci. Lett. 156, 1–11 (1998)

    Article  ADS  CAS  Google Scholar 

  28. Hooft, E. & Detrick, R. S. The role of density in the accumulation of basaltic melts at mid-ocean ridges. Geophys. Res. Lett. 20, 423–426 (1993)

    Article  ADS  CAS  Google Scholar 

  29. Phipps Morgan, J. & Chen, Y. J. The genesis of oceanic crust: magma injection, hydrothermal circulation, and crustal flow. J. Geophys. Res. 98, 6283–6297 (1993)

    Article  ADS  Google Scholar 

  30. Stakes, D. S. et al. The Cleft revealed: geologic, magnetic, and morphologic evidence for construction of upper oceanic crust along the southern Juan de Fuca Ridge. Geochem. Geophys. Geosyst. 7 Q04003 10.1029/2005GC001038 (2006)

    Article  ADS  CAS  Google Scholar 

  31. Barth, G. A. & Mutter, J. C. Variability in oceanic crustal thickness and structure: multichannel seismic reflection results from the northern East Pacific Rise. J. Geophys. Res. 101, 17951–17975 (1996)

    Article  ADS  Google Scholar 

  32. Dilek, Y., Moores, E. M. & Furnes, H. in Faulting and Magmatism at Mid-Ocean Ridges (eds Buck, W. R. et al.) 153–176 (Geophysical Monograph Series Vol. 106, AGU, 1998)

    Google Scholar 

  33. Coogan, L. A. et al. Petrology and geochemistry of the lower ocean crust formed at the East Pacific Rise and exposed at Hess Deep: a synthesis and new results. Geochem. Geophys. Geosyst. 3 8604 10.1029/2001GC000230 (2002)

    Article  ADS  CAS  Google Scholar 

  34. Miller, D. J. & Christensen, N. I. Seismic velocities of lower crustal and upper mantle rocks from the slow spreading Mid-Atlantic Ridge, south of the Kane transform zone (MARK). Proc. ODP Sci. Res. 153, 437–454 (1997)

    CAS  Google Scholar 

  35. Christensen, N. I. Compressional wave velocities in rocks at high temperatures and pressures, critical thermal gradients, and crustal low-velocity zones. J. Geophys. Res. 84, 6849–6857 (1979)

    Article  ADS  Google Scholar 

  36. Christensen, N. I. Poisson's ratio and crustal seismology. J. Geophys. Res. 101, 3139–3156 (1996)

    Article  ADS  CAS  Google Scholar 

  37. Karson, J. A., Collins, J. A. & Casey, J. F. Geologic and seismic velocity structure of the crust/mantle transition in the Bay of Islands ophiolite complex. J. Geophys. Res. 89, 6126–6138 (1984)

    Article  ADS  Google Scholar 

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This research was supported by the US NSF. We thank the captain, crew and scientific party of RV Maurice Ewing Cruise 0207.

Author Contributions All authors participated in the data acquisition experiment. J.P.C. processed the data, interpreted them, and wrote the paper with contributions from all of the co-authors.

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Correspondence to J. Pablo Canales.

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Canales, J., Nedimović, M., Kent, G. et al. Seismic reflection images of a near-axis melt sill within the lower crust at the Juan de Fuca ridge. Nature 460, 89–93 (2009).

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