Scale-invariant topography and porosity variations in fluvial sedimentary basins

Jon Pelletier, D. L. Turcotte

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

We consider a model of a floodplain evolving with channel avulsion, deposition, and erosion. Avulsion is modeled as a random process in space and time. Sediment transport is modeled by the diffusion equation (Culling's model). The power spectrum of variations in the topographic profiles predicted by the model S(k) is proportional to k-2 (where k is the wavenumber). This is the Brown noise often observed in topography. The power spectrum of variations in fhe local elevation in time is proportional to f-3/2 (where f is the frequency). The model prediction of Brown noise floodplain topography is roughly consistent with spectal analyses of microtopography measured with laser altimetry. We inferred Brown noise paleotopography by comparing the pair correlation function of showing wells in the Denver and Powder River basins with a synthetic oil field based on a caprock with Brown noise topography. Topographic control of variations in the grain size of deposited sediment suggests that porosity variations may exhibit the scale invariance predicted for the topographic profile. To illustrate vertical scale invariance in porosity variations, we computed the power spectrum of vertical porosity well logs in 15 offshore wells in the Gulf of Mexico. At spatial scales above 3 m we find an average power spectral exponent of -1.4, close to our model prediction of -1.5.

Original languageEnglish (US)
Pages (from-to)28165-28175
Number of pages11
JournalJournal of Geophysical Research: Space Physics
Volume101
Issue number12
StatePublished - Dec 10 1996
Externally publishedYes

Fingerprint

sedimentary basin
Topography
topography
Porosity
porosity
Power spectrum
power spectra
avulsion
Invariance
well
floodplain
invariance
paleotopography
culling
oil fields
altimetry
river basins
sediment transport
Gulf of Mexico
microtopography

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)
  • Atmospheric Science
  • Geochemistry and Petrology
  • Geophysics
  • Oceanography
  • Space and Planetary Science
  • Astronomy and Astrophysics
  • Earth and Planetary Sciences(all)
  • Environmental Science(all)

Cite this

Scale-invariant topography and porosity variations in fluvial sedimentary basins. / Pelletier, Jon; Turcotte, D. L.

In: Journal of Geophysical Research: Space Physics, Vol. 101, No. 12, 10.12.1996, p. 28165-28175.

Research output: Contribution to journalArticle

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