Just found some time to look at this early Nov posting. Pushing the early Archean boundaries is really exciting.
From Nora Noffke et al. republished in Sci-News.com:
“The Pilbara region of Western Australia is one of the rare geological regions that provides insight into the early evolution of life on Earth,” explained Prof David Wacey from the University of Western Australia, who is a co-author of the paper published in the journal Astrobiology.
“Mound-like deposits created by ancient bacteria, called stromatolites, and microfossils of bacteria have previously been discovered in this region.”
“However, a phenomenon called microbially induced sedimentary structures had not previously been seen in rocks of this great age.”
Microbially induced sedimentary structures were created by microbial mats as the microbial communities responded to changes in physical sediment dynamics.
“A common example would be the binding together of sediment grains by microbes to prevent their erosion by water currents.”
“The significance of microbially induced sedimentary structures is that they not only demonstrate the presence of life, but also the presence of whole microbial ecosystems that could co-ordinate with one another to respond to changes in their environment.”
Left: 3.48 billion-year-old macrostructures from the Dresser Formation in Pilbara, Western Australia. Right: possible modern equivalents. Scale bars – 1 cm. Image credit: Nora Noffke et al.
Nora Noffke et al. Microbially Induced Sedimentary Structures Recording an Ancient Ecosystem in the ca. 3.48 Billion-Year-Old Dresser Formation, Pilbara, Western Australia. Astrobiology, published online November 8, 2013; doi: 10.1089/ast.2013.1030