The Sirius Passet Lagerstatte: silica death masking opens the window on the earliest matground community of the Cambrian explosion

Strang, K.M.; Armstrong, H.A.; Harper, D.A.T.; Trabucho-Alexandre, João P.

doi:10.1111/let.12174

The Sirius Passet Lagerstatte: silica death masking opens the window on the earliest matground community of the Cambrian explosion

Strang, K.M.; Armstrong, H.A.; Harper, D.A.T.; Trabucho-Alexandre, João P.

Authors

K.M. Strang

H.A. Armstrong

Professor David Harper david.harper@durham.ac.uk
Emeritus Professor

João P. Trabucho-Alexandre

Abstract

The Sirius Passet Lagerstätte (SP), Peary Land, North Greenland, occurs in black slates deposited at or just below storm wave base. It represents the earliest Cambrian microbial mat community with exceptional preservation, predating the Burgess Shale by 10 million years. Trilobites from the SP are preserved as complete, three-dimensional, concave hyporelief external moulds and convex epirelief casts. External moulds are shown to consist of a thin veneer of authigenic silica. The casts are formed from silicified cyanobacterial mat material. Silicification in both cases occurred shortly after death within benthic cyanobacterial mats. Pore waters were alkali, silica-saturated, high in ferric iron but low in oxygen and sulphate. Excess silica was likely derived from remobilized biogenic silica. The remarkable siliceous death mask preservation opens a new window on the environment and location of the Cambrian Explosion. This window closed with the appearance of abundant mat grazers later as the Cambrian Explosion intensified.

Citation

Strang, K., Armstrong, H., Harper, D., & Trabucho-Alexandre, J. P. (2016). The Sirius Passet Lagerstatte: silica death masking opens the window on the earliest matground community of the Cambrian explosion. Lethaia: An International Journal of Palaeontology and Stratigraphy, 49(4), 631-643. https://doi.org/10.1111/let.12174

Journal Article Type	Article
Acceptance Date	Dec 11, 2015
Online Publication Date	Apr 19, 2016
Publication Date	Oct 1, 2016
Deposit Date	May 30, 2016
Publicly Available Date	May 31, 2016
Journal	Lethaia
Print ISSN	0024-1164
Electronic ISSN	1502-3931
Publisher	Scandinavian University Press
Peer Reviewed	Peer Reviewed
Volume	49
Issue	4
Pages	631-643
DOI	https://doi.org/10.1111/let.12174

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Advance online version © 2016 The Authors Lethaia published by John Wiley & Sons Ltd on behalf of Lethaia Foundation. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.