Letter | Published:

Discovery of a magma chamber and faults beneath a Mid-Atlantic Ridge hydrothermal field

Abstract

Crust at slow-spreading ridges is formed by a combination of magmatic and tectonic processes, with magmatic accretion possibly involving short-lived crustal magma chambers1. The reflections of seismic waves from crustal magma chambers have been observed beneath intermediate2,3 and fast-spreading centres4,5, but it has been difficult to image such magma chambers beneath slow-spreading centres6,7, owing to rough seafloor topography and associated seafloor scattering7,8. In the absence of any images of magma chambers6 or of subsurface near-axis faults, it has been difficult to characterize the interplay of magmatic and tectonic processes in crustal accretion and hydrothermal circulation at slow-spreading ridges. Here we report the presence of a crustal magma chamber beneath the slow-spreading Lucky Strike segment of the Mid-Atlantic Ridge. The reflection from the top of the magma chamber, centred beneath the Lucky Strike volcano and hydrothermal field, is approximately 3 km beneath the sea floor, 3–4 km wide and extends up to 7 km along-axis. We suggest that this magma chamber provides the heat for the active hydrothermal vent field above it. We also observe axial valley bounding faults that seem to penetrate down to the magma chamber depth as well as a set of inward-dipping faults cutting through the volcanic edifice, suggesting continuous interactions between tectonic and magmatic processes.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Ethics declarations

Competing interests

Reprints and permissions information is available at www.nature.com/reprints. The authors declare no competing financial interests.

References

  1. 1

    Cannat, M. Emplacement of mantle rocks in the seafloor at mid-ocean ridges. J. Geophys. Res. 98, 4163–4172 (1993)

  2. 2

    Collier, J. S. & Sinha, M. C. Seismic images of a magma chamber beneath the Lau Basin back-arc spreading centre. Nature 346, 646–648 (1990)

  3. 3

    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, doi:10.1029/2005/JB003630 (2005)

  4. 4

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

  5. 5

    Kent, G. M. et al. Evidence from three-dimensional reflectivity images for enhanced melt supply beneath mid-ocean-ridge discontinuities. Nature 406, 614–618 (2000)

  6. 6

    Detrick, R. S., Mutter, J. C., Buhl, P. & Kim, I. I. No evidence from multichannel reflection data for a crustal magma chamber in the MARK area on the Mid-Atlantic Ridge. Nature 347, 61–64 (1990)

  7. 7

    Calvert, A. J. Backscattered coherence noise and seismic reflection imaging of the oceanic crust: An example from the rift valley of Mid-Atlantic Ridge at 23°N. J. Geophys. Res. 102, 5119–5133 (1997)

  8. 8

    Navin, D. A., Peirce, C. & Sinha, M. C. The RAMESSES experiment—II. Evidence for accumulated melt beneath a slow spreading ridge from wide-angle refraction and multichannel reflection profiles. Geophys. J. Int. 135, 746–772 (1998)

  9. 9

    Cannat, M. et al. Mid-Atlantic ridge—Azores hotspot interactions: Along-axis migration of a hotspot-derived magmatic pulse 14 to 4 ma ago. Earth Planet. Sci. Lett. 173, 257–269 (1999)

  10. 10

    Dosso, L. et al. The age and distribution of mantle heterogeneity along the Mid-Atlantic Ridge (31–41°N). Earth Planet. Sci. Lett. 170, 269–286 (1999)

  11. 11

    Schilling, J.-G. Fluxes and excess temperatures of mantle plumes inferred from their interaction with migrating mid-ocean ridges. Nature 352, 397–403 (1991)

  12. 12

    Detrick, R. S., Needham, H. D. & Renard, V. Gravity anomalies and crustal thickness variations along the Mid-Atlantic Ridge between 33°N and 40°N. J. Geophys. Res. 100, 3767–3787 (1995)

  13. 13

    Dziak, R. P. et al. Evidence of a recent magma dike intrusion at the slow spreading Lucky Strike segment, Mid-Atlantic Ridge. J. Geophys. Res. 109, B12102, doi:12110.11029/12004JB003141 (2004)

  14. 14

    Escartín, J., Cannat, M., Pouliquen, G., Rabain, A. & Lin, J. Crustal thickness of V-shaped ridges south of the Azores; interaction of the Mid-Atlantic Ridge (36°-39° N) and the Azores hotspot. J. Geophys. Res. 106, 21719–21735 (2001)

  15. 15

    Humphris, S. E., Fornari, D. J., Scheirer, D. S., German, C. R. & Parson, L. M. Geotectonic setting of hydrothermal activity on the summit of Lucky Strike seamount (37°17′N, Mid-Atlantic Ridge). Geochem. Geophys. Geosyst. 3, doi:10.1029/2001GC000284 (2002)

  16. 16

    Langmuir, C. et al. Hydrothermal vents near a mantle hotspot: the Lucky Strike vent field at 37°N on the Mid-Atlantic Ridge. Earth Planet. Sci. Lett. 148, 69–91 (1997)

  17. 17

    Desbruyères, D. et al. Variations in deep-sea hydrothermal vent communities on the Mid-Atlantic Ridge near the Azores plateau. Deep-Sea Res. 48, 1325–1346 (2001)

  18. 18

    Thatcher, W. & Hill, D. P. A simple model for the fault-generated morphology of slow-spreading mid-ocean ridges. J. Geophys. Res. 100, 561–570 (1995)

  19. 19

    Calvert, A. J. Seismic evidence for a magma chamber beneath the slow-spreading Mid-Atlantic Ridge. Nature 377, 410–414 (1995)

  20. 20

    Canales, J. P., Collins, J. A., Escartin, J. & Detrick, R. S. Seismic structure across the rift valley of the Mid-Atlantic ridge at 23°20′N (MARK area): Implications for crustal accretion processes at slow-spreading ridges. J. Geophys. Res. 105, 28411–28425 (2000)

  21. 21

    Toomey, D. R., Purdy, G. M. & Solomon, S. C. Micro-earthquakes beneath the median valley of the Mid-Atlantic ridge near 23°N: tomography and tectonics. J. Geophys. Res. 93, 9093–9112 (1988)

  22. 22

    Chen, Y. & Morgan, W. J. Rift valley/no rift valley transition at mid-ocean ridges. J. Geophys. Res. 95, 17571–17581 (1990)

  23. 23

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

  24. 24

    Smith, D. K. & Cann, J. R. Constructing the upper crust of the Mid-Atlantic Ridge; a reinterpretation based on the Puna Ridge, Kilauea volcano. J. Geophys. Res. 104, 25379–25399 (1999)

  25. 25

    Meurer, W. P. & Gee, J. S. Evidence for the protracted construction of slow-spread oceanic crust by small magmatic injections. Earth Planet. Sci. Lett. 201, 45–55 (2002)

  26. 26

    Cannat, M. How thick is the magmatic crust at slow spreading oceanic ridges? J. Geophys. Res. 101, 2847–2857 (1996)

  27. 27

    Singh, S. C., Kent, G. M., Collier, J. S., Harding, A. J. & Orcutt, J. A. Melt to mush variations in crustal magma properties along the ridge crest at the southern East Pacific Rise. Nature 394, 874–878 (1998)

  28. 28

    Wilcock, W. S. D. & Delaney, J. R. Mid-ocean ridge sulphide deposits: Evidence for heat extraction from magma chambers or cracking fronts? Earth Planet. Sci. Lett. 145, 49–64 (1996)

  29. 29

    Dziak, R. P. & Fox, C. G. Long-term seismicity and ground deformation at Axial Volcano, Juan de Fuca Ridge. Geophys. Res. Lett. 26, 3641–3644 (1999)

  30. 30

    Von Damm, K. L. in Seafloor Hydrothermal Systems (eds Humphris, S. E. et al.) 222–247 (Geophysical Monograph 91, American Geophysical Union (AGU), Washington DC, 1995)

Download references

Acknowledgements

We thank the captain (J.-R. Glehen) and the crew of the RV l'Atalante for providing support during the SISMOMAR cruise, and the seismic team of GENAVIR for acquiring the seismic data. The INSU MOMAR programme funded the acquisition of SISMOMAR project. This is an Institut de Physique du Globe de Paris contribution.

Author information

Competing interests

Reprints and permissions information is available at www.nature.com/reprints. The authors declare no competing financial interests.

Correspondence to Satish C. Singh.

Supplementary information

Supplementary Figure 1

Flattened Seismic reflection images: Seismic sections for lines 8, 20 and 37 flattened using smooth seafloor topography to obtain a more accurate crustal geometry. The AMC reflections are bounded by red circles, layer 2A is indicated by blue squares and the fault reflector ends are indicated by arrows. No vertical exaggeration for a crustal velocity of 5 km/s. (PDF 18920 kb)

Supplementary Figure 2

Seismic reflection images of the AMC and faults: The same seismic sections as in Figure 2, but without highlights and labels (interpretive curves). The fault reflectors are indicated by arrows at their ends. (PDF 21730 kb)

Rights and permissions

Reprints and Permissions

About this article

Further reading

Figure 1: Lucky Strike seismic survey location.
Figure 2: Seismic reflection images of the AMC and faults.
Figure 3: Fault and AMC reflector details.
Figure 4: Three-dimensional schematic view of the AMC and faults.

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.