Numerical modelling of clast rotation during soft-sediment deformation: a case study in Miocene delta deposits

OriginalPaper

Abstract

A numerical model for a rotated clast in a sedimentary matrix is presented, quantifying the deformation in associated soft-sediment deformation structures. All the structures occur in a southwards prograding deltaic sequence within the Miocene Ingering Formation, deposited at the northern margin of the Fohnsdorf Basin (Eastern Alps, Austria). Debris flow and pelitic strata contain boudins, pinch-and-swell structures, ptygmatic folds, rotated top-to-S reverse faults and rigid clasts, developed under different stress conditions within the same layers. The deformation around a 24×10 cm trapezoid-shaped rigid clast, resembling the δ-clast geometry in metamorphic rocks, has been modelled using a 2D finite element modelling software. Under the chosen initial and boundary conditions the rotational behaviour of the clast mainly depends on the proportions of pure and simple shear; best fitting results were attained with a dominantly pure shear deformation (~65–85%), with stretching parallel and shortening normal to the bedding. In this specific model set-up, the initial sedimentary thickness is reduced by 30%, explained by stretching due to sediment creeping and compaction. The high amount of pure shear deformation proposed is compatible with the observed layer-parallel boudinage and pinch-and-swell structures. Rotated faults and ptygmatic folds were caused by the minor component of bedding-parallel simple shear.

Keywords

Soft-sediment deformation Numerical modelling Rigid clast Neogene 

List of symbols

\( \tau _{{ij}} \)

deviatoric components of the stress tensor

\( \ifmmode\expandafter\dot\else\expandafter\.\fi{\varepsilon }_{{ij}} \)

components of the strain rate tensor

i, j

reference to two horizontal and vertical Cartesian directions

η

viscosity

u

velocity

xi, xj

spatial directions

p

pressure

References

  1. Allen JRL (1982) Sedimentary structures. Their character and physical basis, vol 2. Elsevier, Amsterdam, pp 1–663Google Scholar
  2. Baldwin B, Butler CO (1985) Compaction curves. Am Assoc Petrol Geol Bull 69:622–626Google Scholar
  3. Barr TD, Housemann GA (1992) Distribution of deformation around a non-linear ductile medium. Geophys Res Lett 19:1145–1148CrossRefGoogle Scholar
  4. Barr TD, Housemann GA (1996) Deformation fields around a fault embedded in a non-linear ductile medium. Geophys J Int 125:473–490CrossRefGoogle Scholar
  5. Bons PD, Barr TD, tenBrink CE (1996) The development of δ-clasts in non-linear viscous materials: a numerical approach. Tectonophysics 270:29–41CrossRefGoogle Scholar
  6. Ceriani S, Mancktelow NS, Pennacchioni G (2003) Analogue modelling of the influence of shape and particle/matrix interface lubrication on the rotational behaviour of rigid particles in simple shear. J Struct Geol 25:2005–2021CrossRefGoogle Scholar
  7. Farrell SG (1984) A dislocation model applied to slump structures, Ainsa Basin, South Central Pyrenees. J Struct Geol 6:727–736CrossRefGoogle Scholar
  8. Fritsche AE (1997) Catastrophic storm deposit in a sandstone lens of the Eocene Cozy Dell Shale along the Sespe Creek, Ventura County, California. Am Assoc Petrol Geol Bull 81:685–686Google Scholar
  9. Grasemann B, Stüwe K, Vannay J-C (2003) Sense and non-sense of shear in flanking structures. J Struct Geol 25:19–34CrossRefGoogle Scholar
  10. Hölzel M, Wagreich M (2004) Sedimentology of a Miocene delta complex: the type section of the Ingering Formation (Fohnsdorf Basin, Austria). Austrian J Earth Sci 95/96:80–86Google Scholar
  11. Knaust D (2001) Pinch-and-swell structures at the Middle/Upper Muschelkalk boundary (Triassic): evidence of earthquake effects (seismites) in the Germanic Basin. Int J Earth Sci 91:291–303Google Scholar
  12. Kurabayashi H, Shimizu Y, Fujita M (2002) Numerical calculations of bed deformation in multiple and braided bar stream. J Hydrosc Hydraul Eng 20:127–136Google Scholar
  13. Maltman A (1994) The geological deformation of sediments. Chapman & Hall, London, pp 1–362Google Scholar
  14. Mancktelow NS, Arbaret L, Pennacchioni G (2002) Experimental observations on the effect of interface slip on rotation and stabilisation of rigid particles in simple shear and a comparison with natural mylonites. J Struct Geol 24:567–585CrossRefGoogle Scholar
  15. Mandal N, Samanta SK, Chakraborty C (2001) Numerical modeling of heterogeneous flow fields around rigid objects with special reference to particle paths, strain shadows and foliation drag. Tectonophysics 330:177–194CrossRefGoogle Scholar
  16. Marques FO, Bose S (2004) Influence of a permanent low-friction boundary on rotation and flow in rigid inclusion/viscous matrix systems from an analogue perspective. Tectonophysics 382:229–245CrossRefGoogle Scholar
  17. Marques FO, Coelho S (2001) Rotation of rigid elliptical cylinders in viscous simple shear flow: analogue experiments. J Struct Geol 23:609–617CrossRefGoogle Scholar
  18. Marques FO, Taborda R, Antunes J (2005) Influence of a low-viscosity layer between rigid inclusion and viscous matrix on inclusion rotation and matrix flow: a numerical study. Tectonophysics 407:101–115CrossRefGoogle Scholar
  19. Martinsen OJ (1989) Styles of soft-deformation on a Namurian (Carboniferous) delta slope, Western Irish Namurian Basin, Ireland. Geol Soc Lond Spec Publ 41:167–177CrossRefGoogle Scholar
  20. de Meer S, Drury MR, de Bresser JHP, Pennock GM (2002) Deformation mechanisms rheology and tectonics: current status and future perspectives. Spec Publ Geol Soc Lond 200:1–416Google Scholar
  21. Passchier CW (1991) The classification of dilatant flow types. J Struct Geol 13:101–104CrossRefGoogle Scholar
  22. Passchier CW, Trouw RAJ (1996) Microtectonics. Springer, Berlin Heidelberg New York, pp 1–283Google Scholar
  23. Ramsay JG, Huber MI (1983) The techniques of modern structural geology, volume 1: strain analysis. Academic, London, pp 1–308Google Scholar
  24. Sachsenhofer RF, Strauss P, Wagreich M, Abart R, Decker K, Goldbrunner JE, Gruber W, Kriegl C, Spötl C (2000a) Das miozäne Fohnsdorfer Becken—Eine Übersicht. Mitt Ges Geol- Bergbaustud Österr 44:173–190Google Scholar
  25. Sachsenhofer RF, Kogler A, Polesny H, Strauss P, Wagreich M (2000b) The Neogene Fohnsdorf Basin: basin formation and basin inversion during lateral extrusion in the Eastern Alps (Austria). Int J Earth Sci 89:415–430CrossRefGoogle Scholar
  26. Sachsenhofer RF, Bechtel A, Reischenbacher D, Weiss A (2003) Evolution of lacustrine systems along the Miocene Mur-Mürz fault system (Eastern Alps, Austria) and implications on source rocks in pull-apart basins. Mar Petrol Geol 20:83–110CrossRefGoogle Scholar
  27. Samanta SK, Mandal N, Chakraborty C (2002) Development of structures under the influence of heterogeneous flow field around rigid inclusions; insights from theoretical and numerical models. Earth Sci Rev 58:85–119CrossRefGoogle Scholar
  28. Schmid DW (2005) Rigid polygons in shear. In: Bruhn D, Burlini L (eds) High strain zones: structure and physical properties. Geol Soc Lond Spec Publ 245:421–431Google Scholar
  29. Schmid DW, Podladchikov YY (2003) Analytical solutions for deformable elliptical inclusions in general shear. Geophys J Int 155:269–288CrossRefGoogle Scholar
  30. Schmid DW, Podladchikov YY (2004) Are isolated stable rigid clasts in shear zones equivalent to voids? Tectonophysics 384:233–242CrossRefGoogle Scholar
  31. Strauss P, Wagreich M, Decker K, Sachsenhofer RF (2001) Tectonics and sedimentation in the Fohnsdorf-Seckau Basin (Miocene-Austria): from a pull-apart basin to a half-graben. Int J Earth Sci 90:549–559CrossRefGoogle Scholar
  32. Strauss PE, Daxner-Höck G, Wagreich M (2003) Lithostratigraphie, Biostratigraphie und Sedimentologie des Miozäns im Fohnsdorfer Becken (Österreich). Österr Akad Wiss Schriftenreihe Erdw Kom 16:111–140Google Scholar
  33. Truesdell C (1954) The Kinematics of vorticity. Indiana University Press, Bloomington, pp 1–232Google Scholar
  34. Williams BJ, Prentics JE (1957) Slump structures in the Ludlovian rocks of North Herefordshire. Proc Geol Assoc 68:286–293CrossRefGoogle Scholar
  35. Woodcock NH (1976) Structural style in slump sheets. J Geol Soc Lond 132:339–415CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  1. 1.Department of Geodynamics and SedimentologyUniversity of ViennaViennaAustria

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