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Published January 1, 2015 | Supplemental Material
Journal Article Open

Late Devonian carbonate magnetostratigraphy from the Oscar and Horse Spring Ranges, Lennard Shelf, Canning Basin, Western Australia

Abstract

The Late Devonian was a time of major evolutionary change encompassing the fifth largest mass extinction, the Frasnian–Famennian event. In order to establish a chronological framework for global correlation before, during, and following the Frasnian–Famennian mass extinction, we carried out a coupled magnetostratigraphic and biostratigraphic study of two stratigraphic sections in the Upper Devonian carbonate reef complexes of the Lennard Shelf, in the Canning Basin, Western Australia. Magnetostratigraphy from these rocks provides the first high-resolution definition of the Late Devonian magnetic polarity timescale. A 581-m-reference section and an 82-m overlapping section through the marginal slope facies (Napier Formation) of the Oscar Range as well as a 117-m section at Horse Spring (Virgin Hills Formation) were sampled at decimeter to meter scale for magnetostratigraphy. Conodont biostratigraphy was used to correlate both sections, and link magnetostratigraphic polarity zones to a globally established biostratigraphy. A stable, Characteristic Remanent Magnetization (ChRM) with dual polarities (NE, shallowly upward and SW, shallowly downward) is recovered from ∼60% of all samples, with magnetite inferred to be the chief magnetic carrier from thermal demagnetization characteristics. These directions define a geomagnetic pole at 49.5°S/285.8°E and α_(95)=2.4(n=501), placing the Canning Basin at 9.9°S during the Late Devonian, consistent with carbonate reef development at this time. A conservative interpretation of the magnetostratigraphy shows the recovery of multiple reversals from both sections, not including possible cryptochrons and short duration magnetozones. Field tests for primary remanence include positive reversal tests and matching magnetozones from an overlapping section in the Oscar Range. A strong correlation was found between magnetic polarity stratigraphies of the Oscar Range and Horse Spring sections, and we correlate 12 magnetostratigraphic packages. The relative stratigraphic thicknesses of the isochronous sediments from these two sections indicate that carbonate accumulation was ∼4.5× faster in the middle slope deposits at Oscar Range than in the more distal, lower slope Horse Spring deposits for the middle Frasnian through Famennian. The magnetic field during the Late Devonian underwent a relatively high reversal frequency with good potential for regional and global correlation, and should prove useful in deciphering a high-resolution chronostratigraphy across the Lennard Shelf to enable higher confidence examination of reef development across a major biotic crisis.

Additional Information

© 2014 Elsevier B.V. Received 27 November 2012, Revised 27 October 2014, Accepted 31 October 2014, Available online 20 November 2014. Editor: C. Sotin. A special thanks goes first to the Aboriginal tribes of the Bunaba and Gooniyandi (Kuniandi) people who allowed us to work in the lands that hold their rich spiritual history. We would like to thank the Australian Research Council (Grant LP0883812) without whose support this work would have not been possible. Thanks go to Chevron, for offering resources and collaborators for this research. We are grateful to the Geological Survey of Western Australia for use of their vehicles and logistical support. Special thanks go to Colin and Maria Morgan of Wundargoodie Aboriginal Safaris for field and logistical support. Thanks also go to Ray Addenbrooke, Trevor Holland, Kelly Hillbun, Peter Ward, Tom Tobin, Sergei Pisarevsky, Svenja Tulipani, and Luca Lanci for assistance in the field and fruitful discussions. Thanks go to the two reviewers, Cor Langereis and an anonymous reviewer whose input helped significantly improve this manuscript.

Errata

Jeroen Hansma, Eric Tohver, Maodu Yan, Kate Trinajstic, Brett Roelofs, Sarah Peek, Sarah P. Slotznick, Joseph Kirschvink, Ted Playton, Peter Haines, Roger Hocking, Corrigendum to "Late Devonian carbonate magnetostratigraphy from the Oscar and Horse Spring Ranges, Lennard Shelf, Canning Basin, Western Australia" [Earth Planet. Sci. Lett. 409 (2015) 232–242], Earth and Planetary Science Letters, Volume 478, 15 November 2017, Page 46, ISSN 0012-821X, https://doi.org/10.1016/j.epsl.2017.09.015.

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