Terminal proterozoic reorganization of biogeochemical cycles

Article Abstract:

Biogeochemical cycles were reorganized in the late Proterozoic according to an analysis of hydrocarbons from Proterozoic sediments around the globe, indicating an unusually efficient biodegradation mechanism fro algal products. The organic matter floated slowly to the ocean depths and oxygen was largely removed, probably by sulphate-reducing bacteria. The production of fecal matter by newly evolved Cambrian creatures caused rapid sinking of organic matter, allowing oxygen to reach the ocean depths and therefore allowing for the development of sea floor creatures.

Analysis, Water, Water chemistry, Oceanographic research, Paleobotany, Quaternary period, Marine microbiology, Dissolved oxygen

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Biomarker evidence for green and purple sulphur bacteria in a stratified palaeoproterozoic sea

Article Abstract:

Hydrocarbon biomarkers from a 1.64-Gyr-old basin in northern Australia that reveals the ecological structure of mid-Proterozoic marine communities are presented. Phototrophic purple sulphur bacteria are detected in the geological record based on the new carotenoid biomarker okenane, and they seem to have co-existed with communities of green sulphur bacteria.

Australia, Sulfur bacteria, Marine biology, Biological markers

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2-Methylhopanoids as biomarkers for cyanobacterial oxygenic photosynthesis

Article Abstract:

2-methyl-bacteriohopanepolyols are found to occur in a high proportion of cultured cyanobacteria and cyanobacterial mats. The 2-methylhopane hydrocarbon derivatives are rice in organic-rich sediments as old as 2,500 Myr. Such biomarkers provide constraints for the age of the oldest cyanobacteria and the emergence of oxygenic photosynthesis.

Observations, Cyanobacteria, Photosynthesis research

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