Oceanography The Official Magazine of
The Oceanography Society
Volume 25 Issue 01

View Issue TOC
Volume 25, No. 1
Pages 94 - 99

OpenAccess

Active Long-Lived Faults Emerging Along Slow-Spreading Mid-Ocean Ridges

By Deborah K. Smith , Javier Escartín, Hans Schouten , and Johnson R. Cann 
Jump to
Citation References Copyright & Usage
First Paragraph

In the classic mid-ocean ridge model, new seafloor is generated through a combination of magmatic diking feeding lava flows at the spreading axis, and the formation of short-offset, high-angle normal faults that dip toward the axis. These processes lead to the formation of a layered magmatic crust and linear, ridge-parallel abyssal hills on both ridge flanks. This model of ocean crust generation applies well to fast-spreading mid-ocean ridges (i.e., > 80 mm yr–1), but it is not always valid at slower-spreading ridges. Instead, at slow-spreading ridges such as the Mid-Atlantic Ridge (MAR), which is opening at about 25 mm yr–1, the formation of long-lived faults (called detachments) on one flank of the ridge axis is an important process in seafloor formation (Cann et al., 1997; Karson, 1999; MacLeod et al., 2009; Schroeder et al., 2007; Smith et al., 2008; Tucholke et al., 1998). In fact, active detachment faults have been identified along nearly half of the MAR axis between 12° and 35°N (Escartín et al., 2008).

Citation

Smith, D.K., J. Escartín, H. Schouten, and J.R. Cann. 2012. Active long-lived faults emerging along slow-spreading mid-ocean ridges. Oceanography 25(1):94–99, https://doi.org/10.5670/oceanog.2012.07.

References
    Blackman, D.K., J.R. Cann, B. Janssen, and D.K. Smith. 1998. Origin of extensional core complexes: Evidence from the Mid-Atlantic Ridge at Atlantis Fracture Zone. Journal of Geophysical Research 103:21,315–21,333, https://doi.org/10.1029/98JB01756.
  1. Bonatti, E., D. Brunelli, P. Fabretti, M. Ligi, R.A. Portaro, and M. Seyler. 2001. Steady-state creation of crust-free lithosphere at cold spots in mid-ocean ridges. Geology 29:979–982, https://doi.org/10.1130/0091-7613(2001)0292.0.CO;2.
  2. Buck, R.W. 1988. Flexural rotation of normal faults. Tectonics 7:959–973, https://doi.org/10.1029/TC007i005p00959.
  3. Buck, W.R., L.L. Lavier, and A.N.B. Poliakov. 2005. Modes of faulting at mid-ocean ridges. Nature 434:719–723, https://doi.org/10.1038/nature03358.
  4. Cann, J.R., D.K. Blackman, D.K. Smith, E. McAllister, B. Janssen, S. Mello, E. Avgerinos, A.R. Pascoe, and J. Escartín. 1997. Corrugated slip surfaces formed at North Atlantic ridge-transform intersections. Nature 385:329–332.
  5. Cannat, M., D. Sauter, V. Mendel, E. Ruellan, K. Okino, J. Escartín, V. Combier, and M. Baala. 2006. Modes of seafloor generation at a melt-poor ultraslow-spreading ridge. Geology 34:605–608, https://doi.org/10.1130/G22486.1.
  6. deMartin, B.J., R.A. Reves-Sohn, J.P. Canales, and S.E. Humphris. 2007. Kinematics and geometry of active detachment faulting beneath the TAG hydrothermal field on the Mid-Atlantic Ridge. Geology 35:711–714, https://doi.org/10.1130/G23718A.1.
  7. Dick, H.J.B., J.H. Natland, J.C. Alt, W. Bach, D. Bideau, J.S. Gee, S. Haggas, J.G.H. Hertogen, G. Hirth, P.M. Holm, and others. 2000. A long in situ section of the lower ocean crust: Results of ODP Leg 176 drilling at the Southwest Indian Ridge. Earth and Planetary Science Letters 179:31–51, https://doi.org/10.1016/S0012-821X(00)00102-3.
  8. Dick, H.J.B., G. Thompson, and W.B. Bryan. 1981. Low angle faulting and steady-state emplacement of plutonic rocks at ridge-transform intersections (abstract). Eos, Transactions, American Geophysical Union 62:406.
  9. Escartín, J., and J.P. Canales. 2011. Detachments in oceanic lithosphere: Deformation, magmatism, fluid flow and ecosystems. Eos, Transactions, American Geophysical Union 92:31, https://doi.org/10.1029/2011EO040003.
  10. Escartín, J., and M. Cannat. 1999. Ultramafic exposures and the gravity signature of the lithosphere near the Fifteen-Twenty Fracture Zone (Mid-Atlantic Ridge, 14°–16.5°N). Earth and Planetary Science Letters 171:411–424.
  11. Escartín, J., D.K. Smith, J. Cann, H. Schouten, C.H. Langmuir, and S. Escrig. 2008. Central role of detachment faults in accretion of slow-spread oceanic lithosphere. Nature 455:790–794, https://doi.org/10.1038/nature07333.
  12. Garcés, M., and J.S. Gee. 2007. Paleomagnetic evidence of large footwall rotations associated with low-angle faults at the Mid-Atlantic Ridge. Geology 35:279–282, https://doi.org/10.1130/G23165A.1.
  13. Grimes, C.B., B.E. John, M.J. Cheadle, and J.L. Wooden. 2008. Protracted construction of gabbroic crust at a slow spreading ridge: Constraints from 206Pb/238U zircon ages from Atlantis Massif and IODP Hole U1309D (30°N, MAR). Geochemistry Geophysics Geosystems 9, Q08012, https://doi.org/10.1029/2008GC002063.
  14. Ildefonse, B., D.K. Blackman, B.E. John, Y. Ohara, D.J. Miller, C.J. MacLeod, and Integrated Ocean Drilling Program Expeditions 304/305 Science Party. 2007. Oceanic core complexes and crustal accretion at slow-spreading ridges. Geology 35:623–626, https://doi.org/10.1130/G23531A.1.
  15. John, B.E., and M.J. Cheadle. 2010. Deformation and alteration associated with oceanic and continental detachment fault systems: Are they similar? Pp. 175–205 in Diversity of Hydrothermal Systems on Slow Spreading Ocean Ridges. P.A. Rona, C.W. Devey, J. Dyment, and B.J. Murton, eds, Geophysical Monograph Series, vol. 188, American Geophysical Union, Washington, DC, https://doi.org/10.1029/2008GM000772.
  16. Karson, J.A. 1999. Geological investigation of a lineated massif at the Kane Transform Fault: Implications for oceanic core complexes. Philosophical Transactions of the Royal Society of London 357:713–740, https://doi.org/10.1098/rsta.1999.0350.
  17. MacLeod, C.J., J. Calut, J. Escartín, H. Horen, and A. Morris. 2011. Quantitative constraint on footwall rotations at the 15°45’N oceanic core complex, Mid‐Atlantic Ridge: Implications for oceanic detachment fault processes. Geochemistry Geophysics Geosystems 12, Q0AG03, https://doi.org/10.1029/2011GC003503.
  18. MacLeod, C.J., R.C. Searle, B.J. Murton, J.F. Casey, C. Mallows, S.C. Unsworth, K.L. Achenbach, and M. Harris. 2009. Life cycle of oceanic core complexes. Earth and Planetary Science Letters 287:333–344, https://doi.org/10.1016/j.epsl.2009.08.016.
  19. Morris, A., J.S. Gee, N. Pressling, B.E. John, C.J. MacLeod, C.B. Grimes, and R.C. Searle. 2009. Footwall rotation in an oceanic core complex quantified using reoriented Integrated Ocean Drilling Program core samples. Earth and Planetary Science Letters 287:217–228, https://doi.org/10.1016/j.epsl.2009.08.007.
  20. Okino, K., K. Matsuda, D.M. Christie, Y. Nogi, and K. Koizumi. 2004. Development of oceanic detachment and asymmetric spreading at the Australian-Antarctic Discordance. Geochemistry Geophysics Geosystems 5, Q12012, https://doi.org/10.1029/2004GC000793.
  21. Olive, J.-A., M.D. Behn, and B.E. Tucholke. 2010. The structure of oceanic core complexes controlled by the depth distribution of magma emplacement. Nature Geoscience 3:491–495, https://doi.org/10.1038/NGEO888.
  22. Reston, T.J., and C.R. Ranero. 2011. The 3-D geometry of detachment faulting at mid-ocean ridges. Geochemistry Geophysics Geosystems 12, Q0AG05, https://doi.org/10.1029/2011GC003666.
  23. Schouten, H., D.K. Smith, J.R. Cann, and J. Escartín. 2010. Tectonic versus magmatic extension in the presence of core complexes at slow-spreading ridges from a visualization of faulted seafloor topography. Geology 38:615–618, https://doi.org/10.1130/G30803.1.
  24. Schroeder, T., M. Cheadle, H.J.B. Dick, U. Faul, J.F. Casey, and P.B. Kelemen. 2007. Non-volcanic seafloor spreading and corner-flow rotation accommodated by extensional faulting at 15°N on the Mid Atlantic Ridge: A structural synthesis of ODP Leg 209. Geochemistry Geophysics Geosystems 8, Q06015, https://doi.org/10.1029/2006GC001567.
  25. Smith, D.K., J.R. Cann, and J. Escartín. 2006. Widespread active detachment faulting and core complex formation near 13°N on the Mid-Atlantic Ridge. Nature 442:440–443, https://doi.org/10.1038/nature04950.
  26. Smith, D.K., J. Escartín, H. Schouten, and J.R. Cann. 2008. Fault rotation and core complex formation: Significant processes in seafloor formation at slow-spreading mid-ocean ridges (Mid-Atlantic Ridge, 13–25°N). Geochemistry Geophysics Geosystems 9, Q03003, https://doi.org/10.1029/2007GC001699.
  27. Smith, D.K., M. Tolstoy, C.G. Fox, D.R. Bohnenstiehl, H. Matsumoto, and M.J. Fowler. 2002. Hydroacoustic monitoring of seismicity at the slow-spreading Mid-Atlantic Ridge. Geophysical Research Letters 29(11), 1518, https://doi.org/10.1029/2001GL013912.
  28. Tucholke, B., M.D. Behn, W.R. Buck, and J. Lin. 2008. Role of melt supply in oceanic detachment faulting and formation of megamullions. Geology 36:455–458, https://doi.org/10.1130/G24639A.1.
  29. Tucholke, B.E., J. Lin, and M.C. Kleinrock. 1998. Megamullions and mullion structure defining oceanic metamorphic core complexes on the Mid-Atlantic Ridge. Journal of Geophysical Research 103:9,857–9,866, https://doi.org/10.1029/98JB00167.
Copyright & Usage

This is an open access article made available under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution, and reproduction in any medium or format as long as users cite the materials appropriately, provide a link to the Creative Commons license, and indicate the changes that were made to the original content. Images, animations, videos, or other third-party material used in articles are included in the Creative Commons license unless indicated otherwise in a credit line to the material. If the material is not included in the article’s Creative Commons license, users will need to obtain permission directly from the license holder to reproduce the material.