Related Experiment Video
Updated: Jul 26, 2026

Laboratory Simulation of an Iron(II)-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria
Published on: July 24, 2016
3.4-Billion-year-old biogenic pyrites from Barberton, South Africa: sulfur isotope evidence
H Ohmoto1, T Kakegawa, D R Lowe
1Department of Geosciences, The Pennsylvania State University, University Park 16802, USA.
Abstract:
Laser ablation mass spectroscopy analyses of sulfur isotopic compositions of microscopic-sized grains of pyrite that formed about 3.4 billion years ago in the Barberton Greenstone Belt, South Africa, show that the pyrite formed by bacterial reduction of seawater sulfate. These data imply that by about 3.4 billion years ago sulfate-reducing bacteria had become active, the oceans were rich in sulfate, and the atmosphere contained appreciable amounts (>>10(-13) of the present atmospheric level) of free oxygen.
Related Concept Videos
The Sulfur Cycle
Sulfur Assimilation
Diversity of Archaea III
Origin of Photosynthesis
Microbes and the Sulfur Cycle
Acid Mine Drainage

