『Abstract
Fossil evidence of the existence of life during the Archean Eon
of Earth history (>2500 Ma) is summarized. Data are outlined for
48 Archean deposits reported to contain biogenic stromatolites
and for 14 such units that contain a total of 40 morphotypes of
described microfossils. Among the oldest of these putatively microfossiliferous
units is a brecciated chert of the 〜3465 Ma Apex Basalt of Western
Australia. The paleoenvironment, carbonaceous composition, mode
of preservation, and ,morphology of the Apex microbe-like filaments,
backed by new evidence of their cellular structure provided by
two- and three-dimensional Raman imagery, support their biogenic
interpretation. Such data, together with the presence of stromatolites,
microfossils, and carbon isotopic evidence of biological activity
in similarly aged deposits, indicate that the antiquity of life
on Earth extends to at least 〜3500 Ma.
Keywords: Archean; Stromatolites; Microfossils; Oldest life; Raman
imagery; Apex Basalt; Apex chert』
1. Introduction
2. Preservation of the Archean rock record
3. Archean stromatolites
4. Archean microfossils
4.1. The problem of biogenicity
5. Fossil-like filaments of the Apex chert
5.1. Paleoenvironment
5.2. Carbonaceous composition
5.3. Mode of preservation
5.4. Biological morphology
5.5. Cellular fossils or solid pseudofossils?
5.6. Tests of biogenicity
6. Conclusions
Acknowledgements
References