Evidence for Greenland’s Archean Stromatolites Questioned

Living stromatolites exposed at Hamelin Pool, Shark Bay, Western Australia. Early microbial life forms on Earth may have produced microbial mats similar to these in Archean time. Image credit: Martin Schmieder

Conical and dome-like layered features in 3,700-million-year-old (Archean) metasediments of West Greenland have been interpreted as fossil algae mounds (stromatolites) and were the earliest physical evidence of life on Earth. However, a new study led by Abigail Allwood (Jet Propulsion Laboratory, Pasadena, CA) in Nature questions the biogenic origin of these features. Three-dimensional structural and geochemical analysis of the cones and domes suggests they formed during tectonic deformation of the host rocks, and so are not algal mounds or evidence of early life. The next oldest physical traces of life on Earth are similar-looking structures in 3,480-million-year-old rocks in Australia. READ MORE