Hydrocarbon generation from bacterial biomass in ca. 1320 million years ago

Abstract

Bacteria are the oldest life on the Earth. Some of them, such as cyanobacteria, can produce oxygen and organic matter through photosynthesis. However, the hydrocarbon generation ability of these bacterial biomass is still unclear. Here we reported the molecular evidence from the wrapped bitumen in well-preserved silicified concretions from the Xiamaling Formation, North China. The absence of steranes indicated negligible contribution of eukaryotic algae to the bitumen. Abundant hopanes, 13α(n-alkyl)-tricyclic terpanes and other biomarkers of bacteria prove that bacterial biogenic organic matter can generate hydrocarbons on a large scale. Combined with our previous microfossils and elements studies, these bitumen were considered to be from the Xiamaling shales, for the intrusion of Yanliao large igneous provinces into the organic-rich Xiamaling shales at ca. 1320 million years ago.