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Petrological evidence supports the death mask model for the preservation of Ediacaran soft-bodied organisms in South Australia

Alexander G. Liu, Sean McMahon, Jack J. Matthews, John W. Still and Alexander T. Brasier
Petrological evidence supports the death mask model for the preservation of Ediacaran soft-bodied organisms in South Australia
Geology (Boulder) (January 2019) 47 (3): 215-218

Abstract

Microbially mediated early diagenetic pyrite formation in the immediate vicinity of organic material has been the favored mechanism by which to explain widespread preservation of soft-bodied organisms in late Ediacaran sedimentary successions, but an alternative rapid silicification model has been proposed for macrofossil preservation in sandstones of the Ediacara Member in South Australia. We here provide petrological evidence from Nilpena National Heritage Site and Ediacara Conservation Park to demonstrate the presence of grain-coating iron oxides, framboidal hematite, and clay minerals along Ediacara Member sandstone bedding planes, including fossil-bearing bed soles. Scanning electron microscope (SEM), cathodoluminescence microscopy (CL), and petrographic data reveal that framboids and grain coatings, which we interpret as oxidized pyrite, formed before the precipitation of silica cements. In conjunction with geochemical and taphonomic considerations, our data suggest that anactualistically high concentrations of silica need not be invoked to explain Ediacara Member fossil preservation: We conclude that the pyritic death mask model remains compelling.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 47
Serial Issue: 3
Title: Petrological evidence supports the death mask model for the preservation of Ediacaran soft-bodied organisms in South Australia
Affiliation: University of Cambridge, Department of Earth Sciences, Cambridge, United Kingdom
Pages: 215-218
Published: 20190118
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 28
Accession Number: 2019-014680
Categories: Invertebrate paleontology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2019077
Illustration Description: illus.
S38°00'00" - S26°00'00", E129°00'00" - E141°00'00"
Secondary Affiliation: University of Edinburgh, GBR, United KingdomMemorial University of Newfoundland, CAN, CanadaUniversity of Aberdeen, GBR, United Kingdom
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201910
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