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Characterization of kerogenous films and taphonomic modes of the Sirius Passet Lagerstätte, Greenland

Topper, Timothy P.; Greco, Francesco; Hofmann, Axel; Beeby, Andrew; Harper, David A.T.

Characterization of kerogenous films and taphonomic modes of the Sirius Passet Lagerstätte, Greenland Thumbnail


Authors

Timothy P. Topper

Francesco Greco

Axel Hofmann

Andrew Beeby



Abstract

The Sirius Passet Lagerstätte (northern Greenland) is an exceptionally well-preserved early Cambrian faunal community containing a diverse array of stem-group euarthropods, lobopodians, worms, sponges, and the iconic Halkieria. Material collected in situ during recent expeditions has yielded a range of fossil specimens that are preserved as two-dimensional, reflective films. Here we document in detail, for the first time from the Sirius Passet, compressed, kerogenous fossil films characteristic of Burgess Shale–type (BST) preservation. The carbon structure and the taphonomic mode associated with these films were investigated using Raman spectroscopy. Our analysis confirms that these reflective films are kerogenous, showing a higher D1 (disordered) band and G (graphite) band intensity and area, indicating a greater concentration of disordered carbon compared to the surrounding matrix. The spectral characteristics of the fossils denote moderately ordered kerogenous matter, indicating that the transitional Buen Formation that hosts the Sirius Passet was thermally altered at a peak temperature of 409 ± 50 °C. Phyllosilicate minerals are associated with the films, but they are not anatomical or taxon-specific, suggesting that the higher thermal maturation of the kerogen in the Sirius Passet produced a uniform distribution of minerals. This is unlike the kerogenous films in the Burgess Shale Lagerstätte (British Columbia, Canada) that have been metamorphosed at a lower temperature of 335 ± 50 °C and typically show an anatomically specific phyllosilicate distribution. Preservation as kerogenous films, however, is not continuous, and the presence of other taphonomic modes not indicative of BST preservation suggests that the Sirius Passet represents a unique and complex deposit.

Citation

Topper, T. P., Greco, F., Hofmann, A., Beeby, A., & Harper, D. A. (2018). Characterization of kerogenous films and taphonomic modes of the Sirius Passet Lagerstätte, Greenland. Geology, 46(4), 359-362. https://doi.org/10.1130/g39930.1

Journal Article Type Article
Acceptance Date Jan 25, 2018
Online Publication Date Feb 15, 2018
Publication Date Apr 1, 2018
Deposit Date Jan 26, 2018
Publicly Available Date Jan 29, 2018
Journal Geology
Print ISSN 0091-7613
Electronic ISSN 1943-2682
Publisher Geological Society of America
Peer Reviewed Peer Reviewed
Volume 46
Issue 4
Pages 359-362
DOI https://doi.org/10.1130/g39930.1

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Copyright Statement
© 2018 The Authors Gold Open Access: This paper is published under the terms of the CC-BY license




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