Dominic Papineau, Prof. SHE Zhenbing, and postdoc Matthew Dodd from CUG worked with a couple of research institutions to find out that diverse microbial activities on Earth date back to at least 3.75 billion years ago. The research challenges old beliefs about when life began on Earth, and the results are published in Science Advances. The abstract of the paper is as follows.
The oldest putative fossils occur as hematite filaments and tubes in jasper-carbonate banded iron formations from the 4280- to 3750-Ma Nuvvuagittuq Supracrustal Belt, Québec. If biological in origin, these filaments might have affinities with modern descendants; however, if abiotic, they could indicate complex prebiotic forms on early Earth. Here, we report images of centimeter-size, autochthonous hematite filaments that are pectinate-branching, parallel-aligned, undulated, and containing Fe2+-oxides. These microstructures are considered microfossils because of their mineral associations and resemblance to younger microfossils, modern Fe-bacteria from hydrothermal environments, and the experimental products of heated Fe-oxidizing bacteria. Additional clusters of irregular hematite ellipsoids could reflect abiotic processes of silicification, producing similar structures and thus yielding an uncertain origin. Millimeter-sized chalcopyrite grains within the jasper-carbonate rocks have 34S- and 33S-enrichments consistent with microbial S-disproportionation and an O2-poor atmosphere. Collectively, the observations suggest a diverse microbial ecosystem on the primordial Earth that may be common on other planetary bodies, including Mars.
Transmitted light image of a bundles of pectinate-branching hematite filaments with undulations and tubes and co-occurring clusters of irregular ellipsoids.
Back-scattered Electron Detector (BSE) images of the fossil structure.
CUG, University College London, London Centre for Nanotechnology, U.S. Geological Survey National Center, Memorial University of Newfoundland, Carnegie Institution for Science, and University of Leeds participated in the research.
(Edited and translated from the Chinese version)
