Document Type
Article
Publication Date
2018
DOI
10.1089/ast.2017.1734
Publication Title
Astrobiology
Volume
18
Issue
6
Pages
1-17
Abstract
The ~ 3.48 billion-year-old Dresser Formation, Pilbara Craton, Western Australia, is a key geological unit for the study of Earth's earliest life and the habitats it occupied. Here, we describe a new suite of spheroidal to lenticular microstructures that morphologically resemble some previously reported Archean microfossils. Correlative microscopy shows that these objects have a size distribution, wall ultrastructure, and chemistry that are incompatible with a microfossil origin and instead are interpreted as pyritized and silicified fragments of vesicular volcanic glass. Organic kerogenous material is associated with much of the altered volcanic glass; variable quantities of organic carbon line or fill the insides of some individual vesicles, while relatively large, tufted organic-rich laminae envelop multiple vesicles.
The microstructures reported herein constitute a new type of abiogenic artifact (pseudo-fossil) that must be considered when evaluating potential signs of early life on Earth or elsewhere. In the sample studied here, where hundreds of these microstructures are present, the combined evidence permits a relatively straightforward interpretation as vesicular volcanic glass. However, reworked, isolated, and silicified microstructures of this type may prove particularly problematic in early or extraterrestrial life studies since they adsorb carbon onto their surfaces and are readily pyritized, mimicking a common preservation mechanism for bona fide microfossils. In those cases, nanoscale analysis of wall ultrastructure would be required to firmly exclude a biological origin.
Rights
This Open Access article is distributed under the terms of the Creative Commons License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited.
Original Publication Citation
Wacey, D., Noffke, N., Saunders, M., Guagliardo, P., & Pyle, D. M. (2018). Volcanogenic pseudo-fossils from the ~3.48 Ga Dresser formation, Pilbara, Western Australia. Astrobiology, 18(6), 1-17. doi:10.1089/ast.2017.1734
Repository Citation
Wacey, David; Noffke, Nora; Saunders, Martin; Guagliardo, Paul; and Pyle, David M., "Volcanogenic Pseudo-Fossils From the ~3.48 Ga Dresser Formation, Pilbara, Western Australia" (2018). OES Faculty Publications. 254.
https://digitalcommons.odu.edu/oeas_fac_pubs/254