Layer-by-layer mechanism of smectite illitization and application to a new rate law.

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Abstract

A layer-by-layer mechanism explains important features of mixed-layer clay minerals formed during the illitization of smectite, including the occurrence of randomly interstratified illite/smectite, the transition to ordered interstratifications, and the development of long-range ordering. A variety of solid-state transformation mechanisms were tested with a stochastic model, which accounts for interactions among clay layers. The model produces most successful results when the reaction of smectite layers with one illite nearest neighbour is favoured by a factor of approx two over smectite with no illite neighbours, and over those with two illite neighbours by a factor of ten or more. XRD powder patterns calculated from model results compare well with those of illite/smectite minerals. These results suggest a new kinetic rate law. Solutions to this rate law for reaction within sediments undergoing burial give mineralogical profiles with depth similar to those observed in subsiding sedimentary basins.-J.M.H.

Original languageEnglish (US)
Pages (from-to)136-145
Number of pages10
JournalClays & Clay Minerals
Volume34
Issue number2
DOIs
StatePublished - Jan 1 1986

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ASJC Scopus subject areas

  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)

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