Sedimentation on Continental Margins, II: Application of the Regime Concept

  1. D. J. P. Swift3,
  2. G. F. Oertel3,
  3. R. W. Tillman4 and
  4. J. A. Thorne5
  1. J. A. Thorne1 and
  2. D. J. P. Swift2

Published Online: 14 APR 2009

DOI: 10.1002/9781444303933.ch2

Shelf Sand and Sandstone Bodies: Geometry, Facies and Sequence Stratigraphy

Shelf Sand and Sandstone Bodies: Geometry, Facies and Sequence Stratigraphy

How to Cite

Thorne, J. A. and Swift, D. J. P. (1992) Sedimentation on Continental Margins, II: Application of the Regime Concept, in Shelf Sand and Sandstone Bodies: Geometry, Facies and Sequence Stratigraphy (eds D. J. P. Swift, G. F. Oertel, R. W. Tillman and J. A. Thorne), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303933.ch2

Editor Information

  1. 3

    Norfolk, Virginia, USA

  2. 4

    Tulsa, Oklahoma, USA

  3. 5

    Plano, Texas, USA

Author Information

  1. 1

    Research and Technical Services, ARCO Oil and Gas Company, Plano, TX 75075, USA

  2. 2

    Department of Oceanography, Old Dominion University, Norfolk, VA 23529, USA

Publication History

  1. Published Online: 14 APR 2009
  2. Published Print: 30 JAN 1992

ISBN Information

Print ISBN: 9780632032372

Online ISBN: 9781444303933

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Keywords:

  • sedimentation on continental margins II - regime concept application;
  • theory of steady-state sedimentation (regime theory) - analysis of river systems and landscape evolution;
  • natural development of stratigraphic sequences periods of 108 years;
  • regime sedimentation kinds;
  • regime conditions of Louisiana prodelta shelf;
  • regime models to sequence stratigraphy;
  • eustatic sea-level curve for generation of simulations;
  • coastal engineering approach to shallow-water regime

Summary

The theory of steady-state sedimentation (regime theory) has been applied extensively to the analysis of river systems and landscape evolution. In the regime concept, sedimentation systems are governed at geological scales by interdependent variables, whose mutual adjustments maintain a state of dynamic equilibrium. Regime models may be described in terms of equilibrium surfaces controlled by homeostatic responses of erosion or deposition. Regime theory offers geomorphologists a means to realize the consequences of the small-scale behaviour of sedimentary particles at large time and space-scales. The success of regime theory in geomorphological (denudation) modelling indicates that it is an appropriate tool for the complementary task of stratigraphic (basin accumulation) modelling.

The depositional regime, within the context of quantitative stratigraphic models, can thus be defined as the state of the geohistorical variables. These are sediment input rate (Q), sediment character (M), the sediment transport rate (D), and the rate of relative sea-level change (R). A change in any of the geohistorical variables produces, by definition, a change in depositional regime. Topographic profiles are one type of theoretical simplification of the equilibria governed by regime sedimentation. Such a topographic profile in defining the geometry of the resulting sedimentary deposit depends on its type, of which there are five: (1) graded stream profile; (2) isostatic equilibrium profile; (3) coastal equilibrium profile, R-dependent case; (4) coastal equilibrium profile, Q-dependent, advective case; and (5) coastal equilibrium profile, Q-dependent, diffusive case. The R-dependent coastal profile model describes autochthonous (transgressive, sediment starved) regimes, while the Q-dependent profile model describes allochthonous (regressive, sediment flooded) regimes. The isostatic equilibrium model is useful for investigating the behaviour of the continental margin depositional regime at larger time and space-scales.

Shelf depositional regimes, operating through time in response to shifting process variables, create in this fashion the depositional sequences of the rock record. Two examples of regime sedimentation are illustrated. The subaqueous topography of the inshore region of the Louisiana prodelta shelf is shown to form a Q-dependent advective profile that has adjusted to regime conditions of wave energy and sediment supply. In a second illustration of regime sedimentation, a hypothetical shelf is examined at the larger time and space-scale governing its coastal equilibrium profile. An algorithm is given, utilizing a simple, R-dependent, coastal equilibrium profile, that can be used to create computer simulations of the ‘systems tracts’ of sequence stratigraphy. This model is used to investigate the effect of sediment supply, rate of subsidence and sea-level fluctuation on these geometries.