Damage zone and slip-surface evolution over μm to km scales in high-porosity Navajo sandstone, Utah

Z.K. Shipton, P.A. Cowie

Research output: Contribution to journalArticle

302 Citations (Scopus)

Abstract

Detailed mapping of throw variations and deformation along two km-scale normal faults in the high-porosity Navajo sandstone, Utah, has been used to investigate fault growth in this lithology. The faults consist of one or more through-going, striated, slip-surfaces, accommodating the greater part of the offset surrounded by a damage zone consisting of deformation band clusters and short, unconnected slip-surfaces. In contrast to previous models for deformation in this lithology, we find that the nucleation of slip-surfaces begins where measurable throw is negligible and deformation bands are forming and increasing in number. The microstructure and porosity of deformation bands and slip surfaces are distinct and independent of the amount of offset that they accommodate, i.e. they represent different and yet contemporaneous deformation mechanisms. The point where measurable throw begins to accumulate (the fault tip) is marked by the first through-going connected slip-surface. Increase in throw towards the centre of the fault results in a three-dimensional strain field, producing orthorhombic structural geometries within the damage zone. We find that the total width of the damage zone increases as offset is accumulated. For these faults, the damage zone width is approximately 2.5 times the total fault throw.
Original languageEnglish
Pages (from-to)1825-1844
Number of pages20
JournalJournal of Structural Geology
Volume23
Issue number12
DOIs
Publication statusPublished - 31 Dec 2001

Keywords

  • slip-surfaces
  • deformation
  • lithology
  • microstructure
  • porosity

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