Dalhousie Geodynamics Group

Department of Oceanography
Dalhousie University
1355 Oxford Street
PO Box 15000
Halifax, NS, B3H 4R2
Canada

You are here: Dalhousie Geodynamics: Research: Salt Tectonics: Continental Margin Salt Tectonics, Scotian Basin

Continental Margin Salt Tectonics

Scotian Basin, Offshore Nova Scotia

Papers

• Albertz, M., C. Beaumont, J.W. Shimeld, S.J. Ings, and S. Gradmann (2010), An Investigation of Salt Tectonic Structural Styles in the Scotian Basin, offshore Atlantic Canada: Paper 1, Comparison of Observations with Geometrically Simple Numerical Models, Tectonics (in press)

  • Markus Albertz
    Department of Oceanography,
    Dalhousie University,
    Halifax, Canada
    Now at: ExxonMobil Upstream Research Company, Houston, USA

  • Chris Beaumont
    Department of Oceanography,
    Dalhousie University,
    Halifax, Canada

  • John W. Shimeld
    Geological Survey of Canada (Atlantic),
    Natural Resources Canada, Bedford Institute of Oceanography,
    Dartmouth, Canada

  • Steven J. Ings
    Department of Oceanography,
    Dalhousie University,
    Halifax, Canada

  • Sofie Gradmann
    Department of Earth Sciences,
    Dalhousie University,
    Halifax, Canada

  The auxiliary material contains 8 animated gif files(*) showing the evolution of the numerical models presented in our first (Paper 1) of two articles on the structural styles associated with salt tectonics in the Scotian Basin, offshore Eastern Canada.

  1. Animation_R.gif   Animation of reference Model R showing the general evolution of a gravity-driven salt system with a simple rectangular salt basin geometry. The results illustrate the seaward flow and thickening of the salt before it spills over the edge of salt basin, landward extension and open ended flow of the salt, increasing climb angle of salt when the progradation rate exceeds the horizontal flow velocity of the salt, and continued roll-over against the rear of the advancing salt creating withdrawal basins.
  2. Animation_A-1.gif   Animation_A-1.gif Animation of Model A-1. The results show the early expulsion and downslope flow of a 2 km thick salt layer, regional normal faulting at the autochthonous edge of the secondary salt sheet and open-ended advance of the sheet, the development of a synkinematic wedge, and the final configuration including landward sigmoidal strata above the salt.
  3. Animation_A-2.gif   Animation_A-2.gif Animation of Model A-2. The results show the evolution of an equivalent model with a 1 km thick salt layer.
  4. Animation_B-1.gif  Animation_B-1.gif Animation of Model B-1. The results indicate seaward Poiseuille flow of salt and thickening against the seaward sediment buttress during predominantly sediment aggradation.
  5. Animation_B-2.gif   Animation_B-2.gif Animation of Model B-2. Deltaic progradation creates a mushroom geometry of the seaward salt and causes the salt to break out of the enclosing overburden when the salt is sufficiently elevated above the seafloor. Continued differential loading expels the salt which advances as a sheet over the seaward sediments by tank tread advance.
  6. Animation_B-3.gif   Animation_B-3.gif Animation of Model B-3. The horizontal advance of the salt sheet is enhanced when seaward sedimentation is absent.
  7. Animation_C-1.gif   Animation_C-1.gif Animation of Model C-1. The density inversion between salt and overburden creates an incipient Rayleigh-Taylor instability at 30 Ma model time. Salt diverges beneath withdrawal minibasins and flows into diapirs. Welding of minibasin floors initiates withdrawal of the diapir flanks, which ultimately results in turtle structures.
  8. Animation_C-2.gif   Animation_C-2.gif Animation of Model C-2. Weaker sediments and higher aggradation rate leads to wider turtle anticlines and detached salt diapirs.

• Albertz, M., and C. Beaumont (2010), An Investigation of Salt Tectonic Structural Styles in the Scotian Basin, offshore Atlantic Canada: Paper 2, Comparison of Observations with Geometrically Complex Numerical Models, Tectonics (in press)

  • Markus Albertz
    Department of Oceanography,
    Dalhousie University,
    Halifax, Canada
    Now at: ExxonMobil Upstream Research Company, Houston, USA

  • Chris Beaumont
    Department of Oceanography,
    Dalhousie University,
    Halifax, Canada

  The auxiliary material contains 22 animated gif files showing the evolution of the numerical models presented in our second (Paper 2) of two articles on the structural styles associated with salt tectonics in the Scotian Basin, offshore Eastern Canada.

  1. Animation_B-4.gif  Animation of Model B-4 (aggradation). The results illustrate the behavior of salt when the basin boundaries have tapers of ca. 3{degree sign}. Salt flows and thickens seaward. Overburden rotates during uplift.
  2. Animation_B-5.gif  Animation of Model B-5 (progradation). Seaward motion of salt is primarily accommodated by an expulsion roller against the rear of the advancing salt and eventually a salt sheet breaks out.
  3. Animation_B-6.gif   Animation of Model B-6 (aggradation). The results illustrate how salt can flow over a seaward basement step up without hindrance.
  4. Animation_B-7.gif   Animation of Model B-7 (progradation). Salt flows over the basement step and thickens seaward. A salt sheet breaks out in the landward direction. Salt expulsion creates type E minibasins and expulsion trails.
  5. Animation_B-8.gif   Animation of Model B-8 (aggradation). The results show how a salt diapir can emerge above a seaward basement step down. Salt flows seaward and inflates both the landward and seaward half of the salt basin. A salt diapir localizes above the basement step.
  6. Animation_B-9a.gif   Animation of Model B-9a (progradation). During progradation, the salt diapirs are trapped under overburden.
  7. Animation_B-9b.gif   Animation of Model B-9b (progradation). Weaker overburden sediments allow a salt sheet to emerge.
  8. Animation_B-10.gif   Animation of Model B-10 (aggradation). The results show how salt flows in a basin which combine a step down and a step up. As in Model B-8, a salt diapir localizes above the step down.
  9. Animation_B-11a.gif   Animation of Model B-11a (progradation). A salt sheet breaks out toward the end of the model time.
  10. Animation_B-11b.gif   Animation of Model B-11b (progradation). Faster progradation causes the sheet to break out ca. 38 Ma earlier.
  11. Animation_B-12.gif   Animation of Model B-12 (aggradation). The results illustrate the effects of deep salt basins. As in previous models with seaward basement step downs, a salt diapir forms above the step. Expulsion of the deep salt creates a large listric normal fault.
  12. Animation_B-13a.gif   Animation of Model B-13a (progradation). Continued expulsion of the deep salt creates type E minibasins and a salt sheet.
  13. Animation_B-13b.gif   Animation of Model B-13b(progradation). A seaward sedimentation hiatus enhances the advance of the salt sheet.
  14. Animation_B-14.gif   Animation of Model B-14 (aggradation). The results illustrate how a basement obstacle with a height that equals the salt thickness divides the basin into two separate subbasins. Salt diapirs grow at the seaward end of either subbasin.
  15. Animation_B-15a.gif   Animation of Model B-15a (progradation). The diapirs are overwhelmed by the overburden and buried.
  16. Animation_B-15b.gif   Animation of Model B-15b (progradation). Weaker overburden allows a salt sheet to form.
  17. Animation_B-16.gif   Animation of Model B-16 (aggradation). The results show the influence of a wide basement obstacle with a height that equals half the salt thickness. Salt flows efficiently seaward and above the basement high. Salt in the landward portions is nearly completely evacuated and it accumulates in the seaward deep portion of the basin.
  18. Animation_B-17.gif   Animation of Model B-17 (progradation). Continued progradation may expel a salt sheet.
  19. Animation_B-18.gif   Animation of Model B-18 (aggradation). The results show the effects of a central basement step in tapered salt basins. Given the reduced flow velocity of salt in the seaward half of the basin (here, the salt thins seaward), a diapir emerges only in at the seaward end of the landward subbasin.
  20. Animation_B-19.gif   Animation of Model B-19 (progradation). Although a pillow forms in the seaward subbasin, both salt structures are buried.
  21. Animation_B-20.gif   Animation of Model B-20 (aggradation). Weaker sediments during the aggradation phase cause salt to climb strata in the landward subbasin.
  22. Animation_B-21.gif   Animation of Model B-21 (progradation). Once salt has advanced over the basement step, it becomes part of the differential load which expels salt from the seaward subbasin. Differential loading and expulsion in the seaward subbasin results in highly complex salt structures, including stacked welds.

*If you experience problems viewing the animations, right-click and save the file to disk before viewing.

This page was last modified on Tuesday, 17-Aug-2010 23:52:06 ADT
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