A reconstruction of Archean biological diversity based on molecular fossils from the 2.78 to 2.45 billion-year-old Mount Bruce Supergroup, Hamersley Basin, Western Australia

摘要: Abstract Bitumens extracted from 2.7 to 2.5 billion-year-old (Ga) shales of the Fortescue and Hamersley Groups in Pilbara Craton, Western Australia, contain traces molecular fossils. Based on a combination characteristics typical many Precambrian bitumens, their consistently unusually high thermal maturities, widespread distribution throughout Basin, bitumens can be characterized as ‘probably Archean age’. Accepting this interpretation, biomarkers open new window biodiversity. The presence hopanes rocks confirms antiquity domain Bacteria, relative concentrations 2α-methylhopanes indicate that cyanobacteria were important primary producers. Oxygenic photosynthesis therefore evolved > Ga ago, well before independent evidence suggests significant levels oxygen accumulated atmosphere. Moreover, abundance cyanobacterial interbedded with oxide-facies banded iron formations (BIF) indicates although some BIF might have been formed by abiotic photochemical processes or anoxygenic phototrophic bacteria, those Group direct consequence biological production. Biomarkers 3β-methylhopane series suggest microaerophilic heterotrophic probably methanotrophs methylotrophs, active late environments. steranes wide range structures abundances like Paleoproterozoic Phanerozoic sediments is convincing for existence eukaryotes Archean, 900 Ma visible fossil lineage arose. Sterol biosynthesis extant requires oxygen. together oxygenic photosynthetic concentration dissolved regions upper water column was equivalent at least ∼1% present atmospheric level (PAL) may sufficient support aerobic respiration.