CNRS / University of Orleans - FR
Dr Frances Westall
The importance of hydrothermal systems for early life
Hydrothermal vents are the favoured location for the origin of life because they provide enclosed small spaces in which the necessary ingredients of life (carbon molecules and liquid water at temperatures ~< 80°C) could associate in the presence of energy sources (heat and mineral surfaces in disequilibrium – chemistry on the rocks). Once started, life could spread to all other habitable niches on the planet. Hydrothermal systems continued to exert a strong influence on life for at least 1 billion years (Ga) after its origin (here hypothesised to be at or before 4.2 Ga): the earliest traces of life occur in the vicinity of hydrothermal vents and show strong evidence of having been influenced by hydrothermal fluids. In this context, the project seeks to answer the following questions. What is the nature of microbial activity in the vicinity of the oldest known hydrothermal systems? Is it possible to document the distribution of different microbial life forms around such systems? Was there a relationship between hydrothermal systems and the origin of photosynthesis, for instance via IR radiation before visible light utilisation, as has been previously suggested? Here we go back in time to the very beginning of photosynthesis and the associations of primitive life forms in and around hydrothermal systems. A dual approach will be used to answer these questions through studies of modern silicifying hydrothermal systems (Yellowstone Park) and comparisons with ~3.53Ga-old systems from Barberton, South Africa. The results will be of invaluable interest in the search for traces of past and/or present life on Mars where recent finds of silica by the Mars Exploration Rovers and by orbital measurements have been attributed to hydrothermal influences.