Marine Geophysical Researches

, Volume 1, Issue 3, pp 261–283 | Cite as

The Vema fracture zone and the tectonics of transverse shear zones in oceanic crustal plates

  • Tjeerd H. Van Andel
  • Richard P. Von Herzen
  • J. D. Phillips


At 11°N latitude, the Mid-Atlantic ridge is offset 300 km by the Vema fracture zone. Between the ridge offset, the fracture consists of an elongate, parallelogram-shaped trough bordered on the north and south by narrow, high walls. The W-E trending valley floor is segmented by basement ridges and troughs which trend W10°N and are deeply buried by sediment. Uniform high heat flow characterizes the valley area. Seismically inactive valleys south of the Vema fracture, also trending W10°N, are interpreted as relict fracture zones. We explain the high heat flow and the shape of the Vema fracture as the results of secondary sea-floor spreading produced by a reorientation of the direction of sea-floor spreading from W10°N to west-east. This reorientation probably began approximately 10 million years ago. Rapid filling of the fracture valley by turbidites from the Demerara Abyssal plain took place during the last million years.

The large amount of differential uplift in the Vema fracture is not explained by the reorientation model. Since the spreading rate across the valley is small compared to that across the ridge crest, we suggest that it takes place by intrusion of very thin dikes that cool rapidly and hence have high viscosity. Upwelling in the fracture valley will thus result in cosiderable loss of hydraulic head, according to models by Sleep and Biehler (1970), and recovery of the lost head could produce valley walls higher than the adjacent ridge crest. We further postulate that the spreading takes place along the edges of the fracture zone rather than in the center. This would account for the uniform distribution of heat flow along the fracture valley and for the lack of disturbance of the valley fill. As a consequence, a median ridge should form in the center, where head loss is compensated in the older crust; such a median ridge may be present. The width of the valley should be a function of the angle and time of reorientation, and of the spreading rate; the width so obtained for the Vema fracture is in accordance with the observed width. If this model is correct, the narrowness of the valley walls implies a thin lithosphere of very limited horizontal strength.


Turbidite Spreading Rate Abyssal Plain High Heat Flow Median Ridge 
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. Bader, R. G. et al.: Initial Reports of the Deep Sea Drilling Project, Vol. 4, Chap. 5 (U.S. Govt. Printing Office) Washington, D. C., 77–92.Google Scholar
  2. BallM. M. and HarrisonC. G. A.: 1970, ‘Crustal Plates in the Central Atlantic’, Science 167, 1128–9.Google Scholar
  3. BallM. M., HarrisonC. G. A., and SupkoP. R.: 1969, ‘Atlantic Opening and the Origin of the Caribbean’, Nature 223, 167–8.Google Scholar
  4. EwingJ. and EwingM.: 1959, ‘Seismic Refraction Measurements in the Atlantic Ocean Basins, in the Mediterranean Sea, on the Mid-Atlantic Ridge, and in the Norwegian Sea’, Bull. Geol. Soc. Am. 70, 291–318.Google Scholar
  5. EwingJ. and EwingM.: 1967, ‘Sediment Distribution of the Mid-Ocean Ridges with Respect to Spreading of the Sea Floor’, Science 156, 1590–2.Google Scholar
  6. FlemingH. S., CherkisN. Z., and HeirtzlerJ. R.: 1970, ‘The Gibbs Fracture Zone: a Double Fracture Zone at 52°30′ N in the Atlantic Ocean’, Marine Geophys. Res. 1, 37–45.Google Scholar
  7. FoxP. J., LowrieA. Jr., and HeezenB. C.: 1969a, ‘Oceanographer Fracture Zone’, Deep-Sea Res. 16, 59–66.Google Scholar
  8. FoxP. J., PitmanW. C. III and ShepardF.: 1969b, ‘Crustal Plates in the Central Atlantic: Evidence for at Least two Poles of Rotation’, Sciences 165, 487–9.Google Scholar
  9. FunnellB. M. and SmithA. G.: 1968, ‘Opening of the Atlantic Ocean’ Nature 219, 1328–33.Google Scholar
  10. HeezenB. C. and TharpM.: 1965, ‘Tectonic Fabric of the Atlantic and Indian Oceans and Continental Drift’ Phil. Trans. Roy. Soc. London, A 258, 90–106.Google Scholar
  11. HeezenB., TharpM., and EwingM.: 1959, ‘The Floors of the Oceans: I. The North Atlantic’, Geol. Soc. Am. Spec. Paper 65, 122.Google Scholar
  12. HeezenB. C., BunceE. T., HerseyJ. B. and TharpM.: 1964a, ‘Chain and Romanche Fracture Zones’, Deep-Sea Res. 11 11–33.Google Scholar
  13. HeezenB. C., GerardR. D., and TharpM.: 1964b, ‘The Vema Fracture Zone in the Equatorial Atlantic’, J. Geophys. Res. 69, 733–9.Google Scholar
  14. HeirtzlerJ. R., DicksonG. O., HerronE. M., PitmanW. C. III and LePichonX.: 1968, ‘Marine Magnetic Anomalies, Geomagnetic Field Reversals, and Motions of the Ocean Floor and Contingents’, J. Geophys. Res. 73, 2119–36.Google Scholar
  15. IAGA, 1969, ‘International Geomagnetic Reference Field 1965 (IGRF)’, J. Geophys. Res. 74, 4407–8.Google Scholar
  16. IsacksB., OliverJ. and SykesL. R.: 1968, ‘Seismology and the new Global Tectonics’, J. Geophys. Res. 73, 5855–99.Google Scholar
  17. LangsethM. G. Jr., LePichonX., and EwingM.: 1966, ‘Crustal Structure of the Mid-Ocean Ridges, 5, Heat Flow Through the Atlantic Ocean Floor and Convection Currents’, J. Geophys. Res. 71, 5321–55.Google Scholar
  18. Lee, W. H. K. and Uyeda, S.: 1965, ‘Review of Heat Flow Data’, in Terrestrial Heat Flow (ed. by W. H. K. Lee), Am. Geophys. Union, Geophys. Monograph 8, 87–190.Google Scholar
  19. LePichonX.: 1968, ‘Sea-Floor Spreading and Continental Drift’, J. Geophys. Res., 73, 3661–98.Google Scholar
  20. MaxwellA. E., VonHerzenR. P., HsuK. J., AndrewsJ. E., SaitoT., PercivalS. F. Jr., MilowE. D. and BoyceR. E.: 1970, ‘Deep Sea Drilling in the South Atlantic’, Science 168, 1047–59.Google Scholar
  21. McGeary, D. F. R.: 1969, ‘Sediments of the Vema Fracture Zone’, Unpubl. Doctor's Diss., University of California, San Diego.Google Scholar
  22. MelsonW. G. and ThompsonG.: 1971, ‘Petrology of a Transform Fault and Adjacent Ridge Segments’, Trans. Roy. Soc. London 268, 423–441.Google Scholar
  23. MenardH. W.: 1964, Marine Geology of the Pacific, McGraw-Hill Book Company, New York, 270 p.Google Scholar
  24. MenardH. W. and DietzR. S.: 1952, ‘Mendocino Submarine Escarpment’, J. Geol. 60, 266–78.Google Scholar
  25. MenardH. W. and AtwaterT.: 1968. ‘Changes in Direction of Sea Floor Spreading’, Nature 219, 463–7.Google Scholar
  26. MiyashiroA., ShidoF., and EwingM.: 1970. ‘Petrologic Models for the Mid-Atlantic Ridge’, Deep-Sea Res. 17, 109–23.Google Scholar
  27. PhillipsJ. D.: 1967, ‘Magnetic Anomalies over the Mid-Atlantic Ridge near 27°N’, Science 157, 920–3.Google Scholar
  28. PhillipsJ. D. and LuyendykB. P.: 1970, ‘Central North Atlantic Plate Motions over the last 40 Million Years’, Science 170, 727–9.Google Scholar
  29. PhillipsJ. D., ThompsonG., VonHerzenR. P., and BowenV. T.: 1969, ‘Mid-Atlantic Ridge near 43°N Latitude’, J. Geophys. Res. 74, 3069–81.Google Scholar
  30. SchneiderE. D. and VogtP. R. 1968, ‘Discontinuities in the History of Sea-Floor Spreading’, Nature, 217, 1212–22.Google Scholar
  31. SleepN. H.: 1969, ‘Sensitivity of Heat Flow and Gravity to the Mechanisms of Sea-Floor Spreading’, J. Geophys. Res. 74, 542–9.Google Scholar
  32. SleepN. H. and BiehlerS.: 1970, ‘Topography and Tectonics at the Intersections of Fracture Zones with Central Rifts’, J. Geophys. Res. 75, 2748–52.Google Scholar
  33. StoverC. W.: 1968, ‘Seismicity of the South Atlantic Ocean’, J. Geophys. Res. 73, 3807–20.Google Scholar
  34. SykesL. R.: 1967, ‘Mechanism of Earthquakes and Nature of Faulting on the Mid-Oceanic Ridges’, J. Geophys. Res. 72, 2131–53.Google Scholar
  35. Talwani, M. and Heirtzler, J. R.: 1964, ‘Computation of Magnetic Anomalies Caused by Two Dimensional Structures of Arbitrary Shape’, in Computers in the Mineral Industries (ed. by G. Parks), Stanford Univ. Press, 469 p.Google Scholar
  36. VacquierV. and VonHerzenR. P.: 1964, ‘Evidence for Connection Between Heat Flow and the Mid-Atlantic Ridge Magnetic Anomaly’, J. Geophys. Res. 69, 1093–1101.Google Scholar
  37. vanAndelTj. H.: 1969, ‘Recent Uplift of the Mid-Atlantic Ridge South of the Vema Fracture Zone’, Earth Planetary Sci. Letters, 7, 228–30.Google Scholar
  38. vanAndelTj. H.: 1970, ‘Structure of the Ascension Fracture Zone’, Trans. Am. Geophys. Union 51, 330.Google Scholar
  39. vanAndelTj. H. and BowinC. O.: 1968: ‘Mid-Atlantic Ridge Between 22° and 23° North Latitude and the Tectonics of Mid-Ocean Rises’, J. Geophys. Res. 73, 1279–98.Google Scholar
  40. vanAndelTj. H. and HeathG. R.: 1970, ‘Tectonics of the Mid-Atlantic Ridge, 6–8° South Latitude’, Marine Geophys. Res. 1, 5–36.Google Scholar
  41. vanAndelTj. H. and KomarP. D.: 1969, ‘Ponded Sediments of the Mid-Atlantic Ridge Between 22° and 23° North Latitude’, Geol. Soc. Am. Bull. 80, 1163–90.Google Scholar
  42. vanAndelTj. H., CorlissJ. B., and BowenV. T.: 1967, ‘The Intersection Between the Mid-Atlantic Ridge and the Vema Fracture Zone in the North Atlantic’, J. Marine Res. 25, 343–51.Google Scholar
  43. vanAndelTj. H., PhillipsJ. D., and VonHerzenR. P.: 1969, ‘Rifting Origin for the Vema Fracture in the North Atlantic’, Earth Planetary Sci. Letters 5, 296–300.Google Scholar
  44. Vine, F. J.: 1968, ‘Magnetic Anomalies Associated with Mid-Ocean Ridge’, in History of the Earth's Crust (ed. by Robert A. Phinney), Princeton Univ. Press, pp. 73–90.Google Scholar
  45. VineF. J. and MatthewsD. H.: 1963, ‘Magnetic Anomalies over Oceanic Ridges’, Nature 199, 947–9.Google Scholar
  46. VonHerzenR. P., SimmonsG., and FolinsbeeA.: 1970, ‘Heat Flow Between the Caribbean Sea and Mid-Atlantic Ridge’, J. Geophys. Res. 75, 1973–84.Google Scholar
  47. WilsonJ. T.: 1965, ‘A New Class of Faults and Their Bearing on Continental Drift’, Nature 207, 343–7.Google Scholar

Copyright information

© D. Reidel Publishing Company 1971

Authors and Affiliations

  • Tjeerd H. Van Andel
    • 1
  • Richard P. Von Herzen
    • 2
  • J. D. Phillips
    • 2
  1. 1.Department of OceanographyOregon State UniversityCorvallisUSA
  2. 2.Woods Hole Oceanographic InstitutionWoods HoleUSA

Personalised recommendations