The effect of carbonate cementation of underthrust sediments on deformation styles during underplating

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Abstract

Fluids expelled during deformation at convergent margins lead to a variety of diagenetic reactions, including carbonate cementation, which alter the rheology of the deforming sediment. Other than vein calcite, carbonates are early calcite replacing framework grains or filling pore spaces, followed by ankerite that occurs mainly as pore-filling cement. Amounts range from 2-16 weight percent in typical samples, averaging about 9 weight percent. Mean porosity filled by carbonate in Kodiak sandstones corresponds to porosities expected at depths of 4.5km in normal compacting sands underthrust at modern convergent margins. The temperatures of formation are difficult to determine precisely, but were probably between 100°C and 200°C. The bulk of cementation occurred before the formation of thrust faults, folds, and slaty cleavage related to underplating. Lithification by cementation changed the rheology of sandstones by 1) filling pore space and increasing peak strength, and 2) increasing cohesion so that particulate flow was no longer a viable deformation mechanism. Lithification before significant deformation contributed to underplating of the Kodiak Formation as relatively coherent duplexes. -from Author

Original languageEnglish (US)
Pages (from-to)9111-9121
Number of pages11
JournalJournal of Geophysical Research E: Planets
Volume95
Issue numberB6
StatePublished - 1990
Externally publishedYes

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ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)
  • Environmental Science(all)

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