3.5 Billion-Year-Old Bacterial Ecosystems Show Evidence of Sedimentary Rock Sequence in Australia

Researchers found evidence of earth's oldest sedimentary rock. Not only are these rare, but findings of 3.5 billion-year-old bacterial ecosystems in Australia reveal the well-preserved remnants of a complex ecosystem.

As the Pilbara district of Western Australia constitutes one of the most famous geological regions, according to background information from the study, mound-like deposits created by ancient photosynthetic bacteria called stromatolites and microfossils of bacteria have been described by scientists in detail. Yet the phenomenon known as microbially induced sedimentary structures (MISS) has not been previously found in the region-structures that are formed from mats of microbial material.

A team of scientists from Old Dominion University and the University of Western Australia described various MISS preserved region's in Dresser Formation as an analyzed point of origin for the material.

The study notes that the Dresser MISS fossils similarly resemble in form and preservation the MISS from other rock samples found, including 2.9 billion-year-old ecosystem Noffke and colleagues found in South Africa.

"This work extends the geological record of MISS by almost 300 million years," Noffke, who is also a professor at ODU, said, via a press release. "Complex mat-forming microbial communities likely existed almost 3.5 billion years ago."

According to such information, the team proposes that these sedimentary structures arose from the interactions of bacterial films within the shoreline sediments of the region. 

"The structures give a very clear signal on what the ancient conditions were, and what the bacteria composing the biofilms were able to do," Noffke said.

MISS are among the targets of Mars rovers, which search for similar formations on that planet's surface. Thus, the team's findings could have relevance for studies of our larger Solar System as well.

More information regarding the study can be found via the journal Astrobiology.