A Revised Alluvial Stratigraphy Model

  1. M. Marzo and
  2. C. Puigdefábregas
  1. J. S. Bridge and
  2. S. D. Mackey

Published Online: 14 APR 2009

DOI: 10.1002/9781444303995.ch22

Alluvial Sedimentation

Alluvial Sedimentation

How to Cite

Bridge, J. S. and Mackey, S. D. (1993) A Revised Alluvial Stratigraphy Model, in Alluvial Sedimentation (eds M. Marzo and C. Puigdefábregas), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303995.ch22

Editor Information

  1. Barcelona, Spain

Author Information

  1. Department of Geological Sciences, State University of New York, PO Box 6000, Binghamton, NY 13902-6000, USA

Publication History

  1. Published Online: 14 APR 2009
  2. Published Print: 16 SEP 1993

ISBN Information

Print ISBN: 9780632035458

Online ISBN: 9781444303995

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Keywords:

  • alluvial stratigraphy;
  • compacted mean floodplain deposition rate;
  • connectedness and multistorey character of channel-belt deposits;
  • distribution and dimensions of channel sandstone bodies;
  • nature of avulsion-related sequences and cyclicity in overbank deposits;
  • relationships between controlling variables and alluvial architecture are complex;
  • periodic degradation superimposed on aggradation;
  • development of three-dimensional mode

Summary

Quantitative models of alluvial stratigraphy have been widely used to interpret the architecture of ancient alluvium. However, with few exceptions, these interpretations have tended to be too simplistic because the complexity of the controls on alluvial architecture has not been appreciated. The alluvial stratigraphy model of Bridge & Leeder has been improved to more accurately simulate alluvial depositional processes and to predict more aspects of alluvial architecture. The revised model predicts: (i) compacted mean floodplain deposition rate; (ii) proportion, connectedness and multistorey character of channel-belt deposits; (iii) the distribution and dimensions of channel sandstone bodies; and (iv) nature of avulsion-related sequences and cyclicity in overbank deposits, including the potential for palaeosol development. Theory and model simulations demonstrate that these architectural features are controlled to varying extents by at least: (i) channel-belt width/floodplain width; (ii) channel depth; (iii) channel-belt deposition rate; (iv) across-floodplain variation in deposition rate; (v) mean avulsion period; (vi) depth of burial (affecting compaction); and (vii) tectonic tilting of the floodplain. The relationships between these controlling variables and alluvial architecture features are complex, and the effects of one controlling variable cannot be considered in isolation from the others. In order to interpret ancient alluvium using this model, it is desirable to observe as many aspects of alluvial architecture as possible. Ideally, this requires large outcrops, closely spaced borehole logs, seismic data, absolute age dating, estimates of burial depths and knowledge of modern fluvial processes.