Bidirectional fabric evolution in Hamelin Pool microbialites, Shark Bay, Western Australia

Researchers at Shark Bay, Western Australia, have uncovered bidirectional fabric evolution in microbialites within Hamelin Pool, revealing that these structures evolve both upward and downward as they grow. The study identified four accretionary mat types—pustular, smooth, colloform, and transitional—and demonstrated that while the surface mats change with water depth, subsurface microfabrics undergo a taphonomic progression from depositional architecture to micritic thickening and cement infilling. This bidirectional evolution suggests microbialites are not solely products of accretionary mat types but also result from early lithification processes, potentially enhancing their preservation in the geological record. The findings were derived from mesoscale and microscale observations, including polished slabs, thin section scans, optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy.

Vitek, B. E., Suosaari, E. P., Oehlert, A. M., Dupraz, C., Pollier, C. G. L., & Reid, R. P. (2023). Bidirectional fabric evolution in Hamelin Pool microbialites, Shark Bay, Western Australia. The Depositional Record, 9(4), 959–988. Portico. https://doi.org/10.1002/dep2.244