(G) High concentrations of individual filaments (arrows) in the bundles of filaments extend outward from filament clusters located in chert layer I a of the hanging wall. Isolated and intertwined filaments occur in a regularly spaced framework that occasionally span the width of chert layer I b of the footwall, whereas only isolated clusters of filaments were identified in chert layer I a of the hanging wall, typically within cusp-shaped cavities.

Photomicrographs in ( B) to ( D) illustrate details of the vein footwall, whereas ( E) to ( G) show the vein hanging wall. The labeled boxed areas in each transmitted light photomicrograph are magnified in the following photo. The image shows the carbonate-replaced lapillistone host rock (HR) cut by several veins filled with carbonaceous chert (I and II) with different CM:chert cement ratios and cavity-fill (botryoidal) chert (III) (figs. ( A) Scan of a thin section in stratigraphic orientation. RESULTS The hydrothermal chert vein system Here, we report the discovery of well-preserved putative filamentous microfossils from a ~3.42-Ga subseafloor hydrothermal vein system from the BGB that provides the oldest evidence for indigenous subsurface microorganisms (section S1) with a methane-based metabolism. In addition to being important for lifeвЂ™s early evolution, seafloor hydrothermal systems could have been the first environment to which life adapted or where it first emerged ( 11вЂ“ 17).

Subseafloor hydrothermal systems generate fluids highly enriched in reduced inorganic chemical species that mix with more oxidized seawater to produce thermal, redox, and proton gradients in a diversity of (micro)habitats ( 11, 12). A close link between chert deposition and synsedimentary, low-temperature hydrothermal activity has been proposed for many of the BGB chert units because of the presence of hydrothermal alteration zones ( 8), cross-cutting chert veins ( 9), and coupled Si-O isotope systematics ( 10). Different depositional environments have been proposed, ranging from tidal-influenced shallow marine to deeper water settings on subsiding volcanic platforms ( 5). Spherical, coccoidal, spindle-shaped, and filamentous microfossils and silicified microbial mats have been reported from marine sedimentary chert units intercalated with a felsic-to-ultramafic volcanic pile ( 4вЂ“ 7).

The Onverwacht Group of the Barberton greenstone belt (BGB) of southern Africa hosts a diverse record of microbial life. While Earth may have been a habitable planet long before the Paleoarchean Era ( 1), as rocks of this age retain a diversity of fossil evidence for life ( 2, 3), the complexity of lifeвЂ™s cellular constituents, range of metabolic pathways, the niches it occupied locally, and global diversity of its habitats remain largely unknown.

Sims 3 into the future robot scanning