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Book Chapter

Ichnological evidence for the Cambrian explosion in the Ediacaran to Cambrian succession of Tanafjord, Finnmark, northern Norway

By
Duncan McIlroy
Duncan McIlroy
1
Department of Earth Sciences, Memorial University of Newfoundland, St John’s, NL, A1B3X5, Canada
2
Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
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Martin D. Brasier
Martin D. Brasier
2
Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
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Published:
January 01, 2017

Abstract

The Ediacaran to Cambrian transition of the Digermul Peninsula consists of an ichnologically rich, thick, conformable, shallow marine siliciclastic succession that crosses the Neoproterozoic–Cambrian boundary. The Tanafjord section has been independently dated by published palynological and new body fossil discoveries. As is also observed at the current Global Stratotype Section and Point (GSSP) for the Ediacaran–Cambrian boundary at Fortune Head in Newfoundland, Canada, there is a marked increase in burrow size and inferred behavioural diversity around the inferred boundary level at a surface without a significant hiatus. The diversity of this trace fossil assemblage presents an opportunity to compare the ichnological first appearance datums between the GSSP and another sedimentologically similar, but palaeogeographically remote, succession. We found that the first appearance datums of taxa in Finnmark broadly support the definition and stratigraphic extents of the Harlaniella podolica, Treptichnus pedum, Rusophycus avalonensis and Cruziana tenella zones. Our work shows that there is a marked increase in ichnodiversity in the lowermost Fortunian, mostly in the form of shallow tier traces. The main post-Fortunian ichnological innovation is the evolution of bulk sediment deposit feeding that is first evidenced by spreiten burrows at around the base of Cambrian Stage 2 in both the GSSP and in the Tanafjord section.

Supplementary material: Additional images of trace fossils from the studied section are available at https://doi.org/10.6084/m9.figshare.c.3462561

Gold Open Access: This article is published under the terms of the CC-BY 3.0 license.

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Contents

Geological Society

Earth System Evolution and Early Life: A Celebration of the Work of Martin Brasier

A. T. Brasier
A. T. Brasier
University of Aberdeen, UK
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D. McIlroy
D. McIlroy
Memorial University of Newfoundland, Canada
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N. McLoughlin
N. McLoughlin
Rhodes University, South Africa
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Geological Society of London
Volume
448
ISBN electronic:
9781786202932
Publication date:
January 01, 2017

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