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.

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
• Public URL: https://durham-repository.worktribe.com/output/1411127