Iron ooid beds of the Carolinefjellet Formation, Spitsbergen, Norway

Jeremy Mutrux, Harmon Maher, Robert Shuster, Troy Hays

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Iron ooid beds are unusual deposits that have been linked to greenhouse conditions and the transgressive flooding of shallow shelves, and which were globally prevalent during certain periods. Within the marine, Aptian-Albian, Carolinefjellet Formation of Spitsbergen, chamosite ooids have been found within distinctive sandstone beds at six localities, and at a consistent stratigraphic position within the basal Dalkjegla Member. Distinctive characteristics include the iron ooids themselves, a coarser grain size, intercalation with silty siderites, grading, cross-beds indicating offshore or longshore transport, and a lack of burrowing. The enclosing sands display planar and hummocky cross-stratification and abundant oscillation ripple marks, and are interpreted as lagoon-attached bar complexes. The stratigraphic position and traits of the iron ooid sands are consistent with seaward storm transport and preservation within interbar swales. Ooids vary in shape considerably, and display evidence for multiple growth events. Nuclei of quartz, opaques, carbonate clasts and laminated crusts are typically encircled by finer grained tangential chamosite and opaque laminae, sometimes with outer overgrowths of calcite and/or radial chamosite. The Dalkjegla Member is the marine portion of a large-scale transgressive tract, attached to underlying fluvio-estuarine Helvetiafjellet Formation strata. A lagoonal environment associated with the basal shales of the Dalkjegla Member represents a logical setting, where riverine iron concentration and iron silicate growth could occur. The Spitsbergen iron ooid beds extend the known occurrence of Cretaceous examples, representing a less common High-Latitude example, and one not directly associated with a transgressive flooding surface.

Original languageEnglish (US)
Pages (from-to)28-43
Number of pages16
JournalPolar Research
Issue number1
StatePublished - Apr 2008


  • Carolinefjellet formation
  • Chamosite
  • Cretaceous
  • Irono oid
  • Spitsbergen
  • Storm

ASJC Scopus subject areas

  • Oceanography
  • Environmental Chemistry
  • Environmental Science(all)
  • Earth and Planetary Sciences (miscellaneous)


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