Strelley Pool Paleoarchaean Stromatolites

Description: The putative stromatolites with microstructures resembling bacteria from the extensive stromatolitic formations of the 3,430-million-year-old Strelley Pool Chert within the Warrawoona Group in Western Australia have been hotly debated ever since their discovery by Lowe (1980, 1983). Others later ascribed conical form genera to abiotic evaporative precipitation, and found no support for the microfossils as biomarkers. Whether the microstructures within the Warrawoona Group stromatolites are the imprints of ancient filamentous and possibly photosynthetic microbes as argued by Schopf and Awramik became a heated debate that remains unresolved. A recent and extensive study of seven distinct stromatolitic form genera by Allwood certainly lends support to proponents of biogenetic origins of the chert, since the simultaneous set of forms is more difficult to explain with known abiogenic processes. However, whether the microstructures are fossil microbes remains unresolved. If they are microbe fossils, there would still remain the critical question of whether they are archaea, cyanobacteria, another type of photosynthetic bacteria, chemosynthetic bacteria, or some combination of these. While the debate rages on there are many who ascribe to the biogenic nature of these deposits.

Reference: Javaux, E.J., Palaeontology: Microfossils from early Earth, Nature Geoscience 4, 663–665 (2011).

Also see: Stromatolites Across Geologic Time