Textural variation in the pyrite-rich ore deposits of the Roros district, Trondheim Region, Norway: implications for pyrite deformation mechanisms

Craig D. Barrie, Nigel J. Cook, Alan P. Boyle

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)

Abstract

The Roros district is a pyrite-rich polymetallic sulfide orefield in the southeastern part of the Trondheim region, Central Norwegian Caledonides. All of the ore deposits at Roros are hosted within a Cambrian to Silurian succession that was deformed and metamorphosed at lower greenschist to lower amphibolite facies conditions during the Caledonian orogeny. Samples from five individual deposits across the orefield have been analyzed using a combination of reflected light petrographic observation, orientation contrast imaging, and electron backscatter diffraction. Results indicate that, whereas samples from each ore deposit have a variety of different textures, all of them preserve plastic deformation in pyrite grains that occurred at peak metamorphic conditions characterized by the development of internal lattice misorientation within pyrite grains and low-angle (similar to 2A degrees) dislocation walls. These observations indicate that the principal deformation mechanisms at peak metamorphic conditions were dislocation glide and creep. The preservation of brittle fracturing represents later overprinting events.

Original languageEnglish
Pages (from-to)51-68
Number of pages18
JournalMineralium Deposita
Volume45
Issue number1
DOIs
Publication statusPublished - Jan 2010

Keywords

  • Roros
  • Pyrite
  • Norwegian Caledonides
  • EBSD
  • Dislocation creep
  • ELECTRON-BACKSCATTER DIFFRACTION
  • CENTRAL SCANDINAVIAN CALEDONIDES
  • EXPERIMENTALLY DEFORMED PYRITE
  • PREFERRED ORIENTATION
  • SULFIDE DEPOSITS
  • POLYCRYSTALLINE PYRITE
  • PLASTIC-DEFORMATION
  • MASSIVE SULFIDES
  • NORTHERN NORWAY
  • AG DEPOSIT

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