Unstable extension of the lithosphere: a mechanical model for Basin-and- Range structure.

R. C. Fletcher, B. Hallet

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To investigate the behavior of the lithosphere undergoing extension, we use a simple rheological model broadly consistent with experimental data on rock creep and with the nature of the brittle/ductile transition. A plastic surface layer overlies a substrate that deforms by power law creep with a stress exponent eta = 3 and an effective viscosity that decreases with depth. In extension this model shows a strong necking instability, provided that the thermal gradient is sufficiently large; otherwise, stable uniform extension is indicated. The predicted structures display uniformly spaced necks or regions of enhanced extension (basins) alternating with regions of reduced extension (ranges). If the depth to the brittle/ductile transition is roughly 10km, as suggested by the maximum depth of seismic faulting, the model yields spacings for the incipient Basin and Range structures of approx 25-60km, in excellent agreement with observation. -Authors

Original languageEnglish (US)
Pages (from-to)7457-7466
Number of pages10
JournalJournal of Geophysical Research
Issue numberB9
StatePublished - 1983

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology


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