User login
2024 events
Sun 31st
12:00-12:30
Serpentinization - the source of energy, catalysts and nutrients for life to emerge on Earth in the Hadean aeon
David J. W. Moriarty
AAQ, VSS, UQ
The emergence of life on Earth 4 billion years ago depended on the reduction of carbon dioxide and nitrogen by hydrogen under alkaline conditions produced by serpentinisation. Serpentinisation occurs when rocks that have a high content of magnesium and iron in the ferrous redox state and low silicate content, react with water percolating through them, producing hydrogen, serpentine, magnetite and brucite. Hydrogen in serpentinising systems also reduces iron and nickel to their elemental state, forming awaruite, which catalyses the carbon dioxide reduction by hydrogen.
The products of reactions catalysed by awaruite and other transition metals include carbon monoxide, formate, methane, acetate and pyruvate; these are primary organic chemicals at the base of networks leading to synthesis of more complex compounds. Amino acids, which are also essential for autocatalytic networks leading to life, are formed from ammonia produced by the reduction of nitrogen (N2) by hydrogen in serpentinising systems. The cofactor in the enzyme nitrogenase, which dates from the last universal common ancestor of bacteria and archaea, contains molybdenum, iron and sulphur in its active centre.
The geological conditions setting the stage for serpentinisation and life to start on Earth suggest it may not have developed with serpentinisation on Mars or Enceladus if they did not have a large amount of carbon dioxide in their oceans when they formed.
Astronomy has been a life-long interest. His research field now is the study of eclipsing binary stars. He is an Honorary Senior Fellow in the UQ School of Mathematics and Physics with the Astrophysics group. He has an observatory near Stanthorpe where he is collaborating on research projects with members of the Variable Stars section of the Royal Astronomical Society of NZ. Between 2016 and 2021, he used the wide field spectrograph on the Australian National University’s 2.3 m telescope at Siding Spring Observatory. He is an Honorary Member of the Astronomical Association of Queensland and, currently, is President. He collaborates with professional astronomers and is an Honorary Associate Member of the Astronomical Society of Australia. David’s professional career has been in the field of microbial biochemistry and ecology, which provides him with the scientific background to explain how life started on Earth more than 4 billion years ago.