Experimental Preservation of Muscle Tissue in Quartz Sand and Kaolinite
Name
19-030 Newman tb.pdf
Description
Accepted version
Size
285.01 KB
Format
Adobe PDF
Checksum (MD5)
4a48b6d8ea5badaf3cbb652cba838494
Author(s)
Newman, Sharon
El Daye, Mirna
Fakra, Sirine C.
Marcus, Matthew A.
Pajusalu, Mihkel
Pruss, Sara B
Smith, Emily F.
Bosak, Tanja
Date Issued
September 2019
Journal
Palaios
Publisher
Society for Sedimentary Geology
Citation
Newman, Sharon A. et al. "Experimental Preservation of Muscle Tissue in Quartz Sand and Kaolinite." Palaios 34, 9 (September 2019): 437–451 © 2020 Society for Sedimentary Geology
Version
Author's final manuscript
Abstract
Siliciclastic sediments of the Ediacaran Period contain exceptionally preserved fossils of macroscopic organisms, including three-dimensional casts and molds commonly found in sandstones and siltstones and some two-dimensional compressions reported in shales. The sporadic and variable associations of these exceptionally preserved macroscopic fossils with pyrite, clay minerals, and microbial fossils and textures complicate our understanding of fossilization processes. This hinders inferences about the evolutionary histories, tissue types, original morphologies, and lifestyles of the enigmatic Ediacara biota. Here, we investigate the delayed decay of scallop muscles buried in quartz sand or kaolinite for 45 days. This process occurs in the presence of microbial activity in mixed redox environments, but in the absence of thick, sealing microbial mats. Microbial processes that mediate organic decay and release the highest concentrations of silica and Fe(II) into the pore fluids are associated with the most extensive tissue decay. Delayed decay and the preservation of thick muscles in sand are associated with less intense microbial iron reduction and the precipitation of iron oxides and iron sulfides that contain Fe(II) or Fe(III). In contrast, muscles buried in kaolinite are coated only by <10 μm-thick clay veneers composed of kaolinite grains and newly formed K- and Fe(II)-rich aluminosilicate phases. Muscles that undergo delayed decay in kaolinite lose more mass relative to the muscles buried in sand and undergo vertical collapse. These findings show that the composition of minerals that coat or precipitate within the tissues and the vertical dimension of the preserved features can depend on the type of sediment that buries the muscles. Similar processes in the zone of oscillating redox likely facilitated the formation of exceptionally preserved macrofossils in Ediacaran siliciclastic sediments.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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Creative Commons Attribution-Noncommercial-Share Alike
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DOI of Published Version
https://doi.org/10.2110/palo.2019.030
