Framboidal pyrite shroud confirms the ‘death mask' model for moldic preservation of ediacaran soft-bodied organism

Liu, Alexander G. (2016) Framboidal pyrite shroud confirms the ‘death mask' model for moldic preservation of ediacaran soft-bodied organism. Palaios, 31 (5). pp. 259-274. ISSN 0833-1351 DOI https://doi.org/10.2110/palo.2015.095

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Abstract

The mechanisms by which soft-bodied organisms were preserved in late Ediacaran deep-marine environments are revealed by petrographic and geochemical investigation of fossil-bearing surfaces from the Conception and St. John's groups (Newfoundland, Canada). Framboidal pyrite veneers are documented on fossil-bearing horizons at multiple localities. The pyrite is interpreted to have formed via microbial processes in the hours to weeks following burial of benthic communities. This finding extends the ‘death mask' model for Ediacaran soft-tissue preservation to deep-marine settings. Remineralization of pyrite to iron oxides and oxyhydroxides is recognized to result from recent oxidation by meteoric fluids in the shallow subsurface. Consideration of other global Ediacaran macrofossil occurrences reveals that pyrite is observed in association with Ediacaran macrofossils preserved in all four previously described styles of moldic preservation (Flinders-, Conception-, Fermeuse- and Nama-type). This suggests that replication of external morphology by framboidal pyrite was a widespread mechanism by which soft-bodied organisms and associated organic surfaces were preserved, in multiple facies and depositional environments, 580–541 million years ago. The extensive global burial of pyrite in medium- to coarse-grained clastics and carbonates is a previously unrecognized yet potentially significant geological sink of iron and sulfur, and may have contributed to rising atmospheric and marine oxygen concentrations across the late Ediacaran interval.

Item Type:	Article
Additional Information:	This additional link is to the University of Bristol repository link where an author accepted version of the paper may be accessed from 19.05.2017 - http://bit.ly/2osLuWk
Uncontrolled Keywords:	NILAREP; IA72
Subjects:	04 - Palaeobiology
Divisions:	04 - Palaeobiology 08 - Green Open Access
Journal or Publication Title:	Palaios
Volume:	31
Page Range:	pp. 259-274
Identification Number:	https://doi.org/10.2110/palo.2015.095
Depositing User:	Sarah Humbert
Date Deposited:	03 Apr 2017 09:56
Last Modified:	03 Apr 2017 10:19
URI:	http://eprints.esc.cam.ac.uk/id/eprint/3864

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