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Sedimentology of SPICE (Steptoean positive carbon isotope excursion): A high-resolution trace fossil and microfabric analysis of the middle to late Cambrian Alum Shale Formation, southern Sweden

Author:
  • Sven O. Egenhoff
  • Neil S. Fishman
  • Per Ahlberg
  • Jörg Maletz
  • Allison Jackson
  • Ketki Kolte
  • Heather Lowers
  • James Mackie
  • Warren Newby
  • Matthew Petrowsky
Publishing year: 2015
Language: English
Pages: 87-102
Publication/Series: Geological Society of America. Special Papers
Volume: 515
Document type: Journal article
Publisher: Geological Society of America

Abstract english

The Cambrian Alum Shale Formation in the Andrarum-3 core from Scania,
southern Sweden, consists of black siliciclastic mudstone with minor carbonate intercalations. Four facies comprise three siliciclastic mudstones and one fine-grained carbonate. The facies reflect deposition along a transect from deep ramp to basin on a Cambrian shelf. The three mudstone facies contain abundant clay clasts and laterally variable siltstone laminae. Bed-load transport processes seem to have dominated deposition on this deep shelf. These sedimentary rocks record mainly event deposition, and only relatively few, thin laminae probably resulted from suspension settling. The Alum Shale Formation deep shelf did not show a bioturbation gradient, but fecal strings are common and Planolites burrows are rare in all mudstone facies. Evidence for biotic colonization indicates that this mudstone environment was not persistently anoxic, but rather was most likely intermittently dysoxic. The Alum Shale Formation in the Andrarum-3 core shows an overall decrease of grain size, preserved energy indicators, and carbonate content upsection interpreted to reflect a deepening
upward. The succession can also be divided into four small-scale fining-upward
cycles that represent deepening, and four overlying coarsening-upward cycles that represent upward shallowing.

Keywords

  • Geology

Other

Published
  • ISSN: 0072-1077
Per Ahlberg
E-mail: per [dot] ahlberg [at] geol [dot] lu [dot] se

Professor

Lithosphere and Biosphere Science

+46 46 222 78 70

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