Marine Geophysical Researches

, Volume 23, Issue 2, pp 123–145 | Cite as

Vp/Vs-ratios from the central Kolbeinsey Ridge to the Jan Mayen Basin, North Atlantic; implications for lithology, porosity and present-day stress field

  • Rolf Mjelde
  • Roar Aurvåg
  • Shuichi Kodaira
  • Hideki Shimamura
  • Karl Gunnarsson
  • Ayako Nakanishi
  • Hajime Shiobara


The horizontal components from twenty Ocean Bottom Seismometers deployed along three profiles near the Kolbeinsey Ridge, North Atlantic, have been modelled with regard to S-waves, based on P-wave models obtained earlier. Two profiles were acquired parallel to the ridge, and the third profile extended eastwards across the continental Jan Mayen Basin. The modelling requires a thin (few 100 m) layer with very high Vp/Vs-ratio (3.5–9.5) at the sea-floor in the area lacking sedimentary cover. The obtained Vp/Vs-ratios for the remaining part of layer 2A, 2B, 3 and upper mantle, correspond to the following lithologies: pillow lavas, sheeted dykes, gabbro and peridotite, respectively. All crustal layers exhibit a decreasing trend in Vp/Vs-ratio away-from-the-axis, interpreted as decreasing porosity and/or crack density in that direction. A significant S-wave azimuthal anisotropy is observed within the thin uppermost layer of basalt near the ridge. The anisotropy is interpreted as being caused by fluid-filled microcracks aligned along the direction of present-day maximum compressive stress, and indicates crustal extension at the ridge itself and perpendicular-to-the-ridge compression 12 km off axis. Spreading along the Kolbeinsey Ridge has most likely been continuous since its initiation ca. 25 Ma: The data do not suggest the presence of an extinct spreading axis between the Kolbeinsey Ridge and the Aegir Ridge as has been proposed earlier. The Vp/Vs-ratios found in the Jan Mayen Basin are compatible with continental crust, overlain by a sedimentary section dominated by shale.


Shale Lithology Continental Crust Crack Density Pillow Lava 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Allen, R. M., Nolet, G., Morgan, W. J., Vogfjord, K., Nettles, M., Ekstrom, G., Bergsson, B. H., Erlendsson, P., Foulger, G. R., Jakobsdottir, S., Julian, B. R., Pritchard, M., Ragnarsson, S., and Stefansson, R., 2002, Plume driven plumbing and crustal formation in Iceland, Journal of Geophysical Research: In press.Google Scholar
  2. Bratt, R. S. and Solomon, S. C., 1984, Compressional and shear wave structure of the East Pacific Rise at 11.20N: Constraints from three-component ocecan bottom seismometers, Journal of Geophysical Research 89, 6095-6110.Google Scholar
  3. Breivik, A., and Mjelde, R., 2001, OBS-98 survey: Final report western continental profiles. IFJ, University of Bergen report. 138 pp.Google Scholar
  4. Breivik, A., Mjelde, R., Grogan, P., Shimamura, H., Murai, Y., Nishimura, Y., and Kuwano, A., 2001, A possible Caledonide arm through the Barents Sea imaged by OBS data, Tectonophysics: In press.Google Scholar
  5. Cann, J. R., 1968, Geological processes at mid-oceanic ridge crests, Geophysical Journal of the Royal Astronomical Society 15, 331-341.Google Scholar
  6. Carlson, R. L. and Miller, D. J., 1997, A new assessment of the abundance of serpentinite in the oceanic crust, Geophysical Research Letters 24, 457-460.Google Scholar
  7. Castagna, J., Batzle, M., and Kan, T. K, 1993, The link between the rock properties and AVO respons, in SEG Geophysical series: Offset-Dependent Reflectivity-Theory and Practice of AVO Analysis 8, 135-171.Google Scholar
  8. Chian, D. and Louden, K. E., 1994, The continent-ocean crustal transition across the southwest Greenland margin, Journal of Geophysical Research 99, 9117-9135.Google Scholar
  9. Christensen, N., 1996, Poissons's ratio and crustal seismology, Journal of Geophysical Research 101, 3139-3156.Google Scholar
  10. Christenson, G. L., Shaw, P. R., and Garmany, J. D., 1997, Shear and compressional wave structure of the East Pacific Rise 9-10N, Journal of Geophysical Research 102, 7821-7835.Google Scholar
  11. Christensen, N. I. and Salisbury, M. H., 1982, Lateral heterogeneity in the seismic structure of the oceanic crust inferred from velocity studies in the Bay of Islands ophiolite, Geophysical Journal of the Royal Astronomical Society 68, 675-688.Google Scholar
  12. Christensen, N. I. and Smewing, J. D., 1981, Geology and seismic structure of the northern section of the Oman ophiolite, Journal of Geophysical Research 86, 2545-2555.Google Scholar
  13. Christensen, N. I. and Salisbury, M. H., 1972, Seafloor spreading, progressive alteration of layer 2 basalts, and associated changes in seismic velocities, Earth and Planetary Science Letters 15, 367-375.Google Scholar
  14. Collier, J. S. and Singh, S. C., 1998, Poisson's ratio structure of young oceanic crust, Journal of Geophysical Research 103, 20981-20996.Google Scholar
  15. Crampin, S., 1990, The scattering of S-waves in the crust, Pure and Applied Geophysics 132, 67-91.Google Scholar
  16. Detrick, R., Collins, J., Stephens, R., and Swift, S., 1994, In situ evidence for nature of the seismic layer 2-3 boundary in oceanic crust, Nature 370, 288-290.Google Scholar
  17. Diachok, O. I., 1991, Critical angle measurements of compressional and shear speeds in the upper crust, Abstract, EOS Transactions, AGU Fall Meeting Supplement 72, 430.Google Scholar
  18. Digranes, P. Mjelde, R., Kodaira, S., Shimamura, H., Kanazawa, T., Shiobara, H., and Berg, E. W., 1996, Modelling Shear waves in OBS data from the Vøring Basin (Northern Norway) by 2-D Ray-tracing, Pure and Applied Geophysics 4, 611-629.Google Scholar
  19. Eldholm, O., Skogseid, J., Sundvor, E., and Myhre, A. M., 1990, The Norwegian-Greenland Sea, in Grantz, A., Johnson, L. and Seeney, J. F., The geology of North America, vol. L, Geological Society of America pp. 350-363.Google Scholar
  20. Eldholm, O., Thiede, J., and Taylor, E., 1989, Evolution of the Vøring Volcanic margin, Proc. Ocean Drill. Program Sci. Results 104, 1033-1065.Google Scholar
  21. Flovenz, O. G., 1980, Seismic structure of the Icelandic crust above layer three and the relation between body wave velocity and the alteration of the basaltic crust, Journal of Geophysics 47, 211-220.Google Scholar
  22. Francis, T. J. G., 1981, Serpentinization faults and their role in the tectonics of slow spreading ridges, Journal of Geophysical Research 86, 11616-11622.Google Scholar
  23. Grevemeyer, I., Weigel, W., Whitmarsh, R. B., Avedik F., and Deghani, G. A., 1997, The Aegir Rift: Crustal structure of an extinct spreading axis, Marine Geophysical Researches 19, 1-23.Google Scholar
  24. Grønlie, G., Chapmann, M., and Talwani, M., 1979, Jan Mayen Ridge and Iceland Plateau: Origin and evolution, Norsk Polarinstitutt Skrift 170, 201-224.Google Scholar
  25. Harding, A. J., Orcutt, J. A., Kappus, M. E., Vera, E. E., Mutter, J. C., Buhl, P., Detrick, R. S., and Brocher, T. M., 1989, Structure of young oceanic crust at 13N on the West Pacific Rise from expanding spread profiles, Journal of Geophysical Research 94, 12163-12196.Google Scholar
  26. Helmberger, D. V. and Morris, G. B., 1970, A travel time and amplitude interpretation of a marine refraction profile: Transformed shear waves, Bull. Seismological Society of America 60, 593-600.Google Scholar
  27. Holbrook, W. S., Mooney, W. D., and Christensen, N. J., 1992, Seismic velocity structure of the deep continental crust, in Fountain, D., Arculus, R., and Kay, R. W. (Eds.), Continental Lower crust, Elsevier, Amsterdam, pp. 451-464.Google Scholar
  28. Hyndman, R., 1979, Poisson's ratio in the oceanic crust-a review, Tectonophysics 59, 321-333.Google Scholar
  29. Johanson, H. P. and Becker, K., 1994, An introduction to the special section on oceanic crustal evolution, Journal of Geophysical Research 99, 2969-2971.Google Scholar
  30. Kanazawa, T. and Shiobara, H., 1994, Newly developed ocean bottom seismometer, Program Abstract, Japan Earth and Planetory Science Joint Meeting 341 (in Japanese).Google Scholar
  31. Kasahara, J., Kamimura, A., Fujie, G., and Hino, R., 2001, Influence of water on earthquake generation along subduction zones, Bull. Earthquake Research Institute, University of Tokyo 76, 289-301.Google Scholar
  32. Kearey, P. and Vine, F., 1996, Global Tectonics, 2nd ed., Blackwell Science Ltd.Google Scholar
  33. Klingelhoefer, F., Geli, L., and White, R., 2000, Geophysical and geochemical constraints on crustal accretion at the veryslow spreading Mohns Ridge, Geophysical Research Letters 27, 1547-1550.Google Scholar
  34. Kent, D. V., Honnorez, N. D., Opdyke, N. D., and Fox, P. J., 1978, Magnetic properties of dredged oceanic gabbros and the source of magnetic anomalies, Geophysical Journal of the Royal Astronomical Society 55, 513-537.Google Scholar
  35. Kern, H., Liu, B., and Popp, T., 1997, Relationship between anisotropy of P and S velocities and anisotropy of attenuation in serpentinite and amphibolite, Journal of Geophysical Research 102, 3051-3065.Google Scholar
  36. Kodaira, S., Mjelde, R., Gunnarsson, K., Shiobara, H., and Shimamura, H., 1998a, Evolution of oceanic crust on the Kolbeinsey Ridge, north of Iceland, over the past 22 Myr, Terra Nova 10, 27-31.Google Scholar
  37. Kodaira, S., Mjelde, R., Gunnarsson, K., Shiobara, H., and Shimamura, H., 1998b, Structure of the JanMayen micro-continent and implications for its evolution, Geophysical Journal International 132, 383-400.Google Scholar
  38. Kodaira, S., Mjelde, R., Gunnarsson, K., Shiobara, H., and Shimamura, H., 1997, Crustal structure of the Kolbeinsey Ridge, North Atlantic, obtained by use of ocean bottom seismographs, Journal of Geophysical Research 102, 3131-3151.Google Scholar
  39. Kodaira, S., Goldschmidt-Rokita, A., Hartmann, J. M., Hirschleber, H. B., Iwasaki, T. Kanazawa, T., Krahn, H., Tomita, S., and Shimamura, H., 1995a, Crustal structure of the Lofoten continental margin, off northern Norway, from ocean bottom seismographis studies, Geophysical Journal International 121, 907-924.Google Scholar
  40. Kodaira, S., Bellenberg, M., Iwasaki, T. Kanazawa, T., Hirschleber, H. B., and Shimamura, H., 1995b, Vp/Vs ratio structure of the Lofoten continental margin, northern Norway, and its geological implications, Geophysical Journal International 124, 724-740.Google Scholar
  41. Meyer, O., Voppep, D., Fleischer, V., Closs, H., and Gerke, K., 1972, Results of bathymetric, magnetic and gravimetric measurements between Iceland and 70N, Deutchse Hydrograph. Z. 25, 193-201.Google Scholar
  42. Minshull, T. A., Muller, M. R., Robinson, C. J., White, R. S., and Bickle, M. J., 1998, Is the oceanic Moho a serpentinitization front? in Mills, R. A., and Harrison, K. (eds), Modern ocean floor processes and the geological record, Geological Society, London, Special Publication 148, 71-80.Google Scholar
  43. Minshull, T. A., White, R. S., Mutter, J. C., Buhl, P., Detrick, R. S., Williams, C. A., and Morris, E., 1991, Crustal structure at the Blake Spur Fracture Zone from expanding spread profiles, Journal of Geophysical Research 96, 9955-9984.Google Scholar
  44. Mjelde, R. and Sellevoll, M. A., 1993, Seismic anisotropy inferred from wide-angle reflections off Lofoten, Norway, indicative of shear-aligned minerals in the upper mantle, Tectonophysics 222, 21-32.Google Scholar
  45. Mjelde, R., Raum, T., Digranes, P., Shimamura, H., Shiobara, H., and Kodaira, S., 2002a. Vp/Vs-ratio along the Vøring Margin, NE Atlantic, derived from OBS-data: Implications on lithology and stress field, Tectonophysics: Submitted. Google Scholar
  46. Mjelde, R., Fjellanger, J. P., Raum, T., Digranes, P., Kodaira, S., Breivik, A., and Shimamura, H., 2002b, Where do P-S converions occur? Analysis of OBS-data from the NE Atlantic Margin, First Break 20.3, 153-160.Google Scholar
  47. Mjelde, R., Breivik, A., Elstad, H., Ryseth, A. E., Skilbrei, J. R., Opsal, J. G., Shimamura, H., Murai, Y., and Nishimura, Y., 2002c, Geological development of the Sørvestsnaget Basin, SW Barents Sea, from ocean bottom seismic, surface seismic and potential field data, Norwegian Journal of Geology: Submitted. Google Scholar
  48. Mjelde, R., Digranes, P., Van Schaack, M., Shimamura, H., Shiobara, H. Kodaira, S., Næss, O., Sørenes, N., and Vågnes, E., 2001, Crustal structure of the outer Vøring Plateau, offshore Norway, from ocean bottom seismic and gravity data, Journal of Geophysical Research 106, 6769-6791.Google Scholar
  49. Mjelde, R., Myhre, B., Sellevoll, M. A., Shimamura, H., Iwasaki, T., and Kanazawa, T., 1996a, Modelling of S-waves from an area covered with flood-basalt off Lofoten, N. Norway, Geophysical Transactions 40, 95-117.Google Scholar
  50. Mjelde, R., Kodaira, S., and Shimamura, H., 1995a, OBS experiment Kolbeinsey Ridge-Jan Mayen Ridge, 2-21 May 1995, Cruise report, University of Bergen, 28 pp.Google Scholar
  51. Mjelde, R., Sellevoll, M. A., Shimamura, H., Iwasaki, T., and Kanazawa, T., 1995b, S-wave anisotropy off Lofoten, Norway, indicative of fluids in the lower crust? Geophysical Journal International 120, 87-96.Google Scholar
  52. Mjelde, R., Sellevoll, M. A., Shimamura, H., Iwasaki, T., and Kanazawa, T., 1992, A crustal study off Lofoten, N. Norway by use of 3-C ocean bottom seismographs, Tectonophysics 212, 269-288.Google Scholar
  53. Morris, E., Detrick, R., Minshull, T. A., Mutter, J. C., White, R. S., Su, W., and Buhl, P., 1993, Seismic structure of oceanic crust in the western north Atlantic, Journal of Geophysical Research 98, 13879-13903.Google Scholar
  54. Myhre, A. M., Eldholm, E., and Sundvor, E., 1984, The Jan Mayen Ridge; present status, Polar Research 2, 47-59.Google Scholar
  55. NAT Study Group, 1985, North Atlantic Transect: A wide-aperture, two-ship multichannel seismic investigation of the oceanic crust, Journal of Geophysical Research 90, 10321-10341.Google Scholar
  56. Raum, T., Mjelde, R., Digranes, P., Shimamura, H., Shiobara, H., and Kodaira, S., 2002, P-and S-wave structure of the Møre Margin, mid-Norway, from wide-angle seismic and gravity data, Tectonophysics: In preparation. Google Scholar
  57. Shimamura, H., 1988, OBS technical description, in Sellevoll, M.A., OBS Cruise report, University of Bergen, 3 pp.Google Scholar
  58. Smallwood, J. R., White, R. S., and Minshull, T. A., 1995, Sea-floor spreading in the presence of the Iceland plume: The structure of the Reykjanes Ridge at 60.40N, Journal of the Geological Society of London 52, 1023-1029.Google Scholar
  59. Spencer, P. and Orcutt, J., 1980, Petrology and porosity of an oceanic crustal site: results from wave from modelling of seismic refraction data, Journal of Geophysical Research 85, 1409-1433.Google Scholar
  60. Sristava, S. P. and Tapscott, C. R., 1986, Plate kinematics of the North Atlantic, in Vogt, P. R. and Tucholke, B. E. (eds), The Geology og North America, Vol.M, The Western North Atlantic Region, Geological Society of America, 379-404.Google Scholar
  61. Talwani, M. and Eldholm, O., 1977, Evolution of Norwegian-Greenland Sea: Recent results and outstanding problems, Geological Society American Bulletin 88, 969-999.Google Scholar
  62. Talwani, M. and Udintsev, G., 1976, Initial reports: Deep Sea Drilling Project, U.S. Government Printing Office, Washington D.C. 38.Google Scholar
  63. Verhoef, J., Roest, W., MacNab, R., and Arkani-Hamed, J., 1996, Magnetic anomalies of the Arctic and North Atlantic oceans and adjacent areas, Geological Survey of Canada Open File 3125a.Google Scholar
  64. Vogt, P. R., 1974, The Icelandic Phenomenon: Imprints of a hot spot on the oceanic crust, and implications for flow below the plates, in Kristjansson, L., Geodynamics of Iceland and the North Atlantic area, NATO Adv. Study Inst. Ser. 49-62.Google Scholar
  65. Vogt, P. G., Johson., G. L., and Kristjansson, L., 1980. Morphology and Magnetic Anomalies North of Iceland, Journal of Geophysics 47, 67-80.Google Scholar
  66. Weir, N. R.W.,White, R. S., Brandsdottir, B., Einarsson, H., Shimamura, H., Shiobara, H., and R. F. Team, 2002, Crustal structure of the northern Reykjanes Ridge and the Reykjanes Peninsula, south-west Iceland, Journal of Geophysical Research: In press.Google Scholar
  67. White, R. S., 1992, Crustal structure and magmatism of the North Atlantic continental margins, Journal of the Geological Society of London 149, 841-854.Google Scholar
  68. White, R. S. and McKenzie, D., 1989, Magmatism at rift zones: The generation of volcanic continental margins and flood basalts, Journal of Geophysical Research 94, 7685-7729.Google Scholar
  69. White, R. S., Westbrook, G. K., Fowler, S. R., Spencer, D., Barton, P. J., Joppen, M., Morgan, J., Bowne, A. M., Prescott, A. M., and Bott, M. H. R., 1987, Hatton Bank (nortwest UK) continental margin structure, Geophysical Journal of the Royal Astronomical Society 89, 265-272.Google Scholar
  70. Zelt, C. A., 1999, Modelling strategies and model assessment for wide-angle seismic traveltime data, Geophysical Journal International 139, 183-204.Google Scholar
  71. Zelt, C. A. and Smith, R. B., 1992, Seismic traveltime inversions for 2-D crustal velocity structure, Geophysical Journal International 108, 16-34.Google Scholar

Copyright information

© Kluwer Academic Publishers 2002

Authors and Affiliations

  • Rolf Mjelde
    • 1
  • Roar Aurvåg
    • 2
  • Shuichi Kodaira
    • 3
  • Hideki Shimamura
    • 4
  • Karl Gunnarsson
    • 5
  • Ayako Nakanishi
    • 6
  • Hajime Shiobara
    • 7
  1. 1.Institute of Solid Earth PhysicsUniv. of BergenBergenNorway
  2. 2.Institute of Solid Earth PhysicsUniv. of BergenBergenNorway
  3. 3.Institute of Seismology and VolcanologyHokkaido UniversitySapporoJapan
  4. 4.Institute of Seismology and Volcanology, Hokkaido UniversitySapporoJapan
  5. 5.National Energy AuthorityReykjavikIceland
  6. 6.Institute of Seismology and VolcanologyHokkaido UniversitySapporoJapan
  7. 7.Institute of Seismology and VolcanologyHokkaido UniversitySapporoJapan

Personalised recommendations