Identification of Regular Sedimentary Cycles Using Walsh Spectral Analysis with Results from the Boom Clay Formation, Belgium

  1. P. L. de Boer2 and
  2. D. G. Smith3
  1. E. van Echelpoel

Published Online: 29 APR 2009

DOI: 10.1002/9781444304039.ch6

Orbital Forcing and Cyclic Sequences

Orbital Forcing and Cyclic Sequences

How to Cite

van Echelpoel, E. (1994) Identification of Regular Sedimentary Cycles Using Walsh Spectral Analysis with Results from the Boom Clay Formation, Belgium, in Orbital Forcing and Cyclic Sequences (eds P. L. de Boer and D. G. Smith), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304039.ch6

Editor Information

  1. 2

    Utrecht, The Netherlands

  2. 3

    London, UK

Author Information

  1. Instituut voor Aardwetenschappen, K.U. Leuven, Redingenstraat 16, B-3000 Leuven, Belgium

Publication History

  1. Published Online: 29 APR 2009
  2. Published Print: 28 JAN 1994

ISBN Information

Print ISBN: 9780632037360

Online ISBN: 9781444304039

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Keywords:

  • identifying regular sedimentary cycles by Walsh spectral analysis;
  • lithostratigraphic parameters;
  • Walsh analysis;
  • Oligocene siliciclastic shelf deposit;
  • position of zero-crossings

Summary

The examination of stratigraphic successions for cyclicity related to orbital variations or Milankovitch cycles relies a great deal upon spectral analysis of selected bio- or lithostratigraphic parameters in measured sections. Recently, Walsh spectral analysis has been introduced for the analysis of digitized sections. Although digitizing is a convenient way to generate long time series, the choice of the coding system used is limited by the nature of the Walsh functions. The effects of coding on the distribution and intensity of powers in Walsh spectra are demonstrated by means of simple models. In some circumstances the bundling of sedimentary cycles, often used to prove Milankovitch-type cycles, cannot be detected by the Walsh approach.

The windowing Walsh analysis gives an impression of the frequency composition of the time series through time. The nature of changes in stratigraphic thickness can be deduced from the set of spectra obtained and important information regarding variations in sedimentation rate can be gained from this scanning technique. The application of the technique is outlined and illustrated for the Boom Clay Formation. This Oligocene siliciclastic shelf deposit is characterized by alternating, laterally persistent beds of silt and clay. The digitized sections, based on grain size and organic matter content, are non-stationary due to the presence of long-term trends. Power spectral analysis of these lithological variations indicates two regular cycles for the Boom Clay Formation. The scale of the cycles and their regularity suggest an indirect link to the 100-ka and 41-ka orbital cycles.