Fossil molecules from cells of bacteria and algae many millions of years old may hold the key to reading life signals from extra terrestrial sources, according to research conducted by AGSO – Geoscience Australia researcher, Dr Graham Logan.
Some molecules within living cells fossilise very well and can reveal evidence of past life, environments and geothermal processes.
Geologists have been studying such fossils in their quest to better understand the formation of major mineral deposits of lead, zinc and silver. Such an understanding will lead to better and more efficient exploration of new Australian mineral deposits.
Dr Logan studied the 1640 million-year old lead-zinc-silver deposit at McArthur River in the Northern Territory.
“We looked for evidence of past life and the impact of the mineral fluids within the ancient rocks,” Dr Logan said. “The mineral deposit was formed through the interaction of hot brines with organic matter. Unusual life forms are often found at such sites in modern environments.
“The fossil molecules provide information about life on earth over 1000 million years before animals evolved. Study of similar places on Mars may provide information about any life on that planet.”
Dr Logan worked with colleagues using a combination of techniques to see if “signals of life” could be detected in rocks collected from the McArthur River Mine.
“The rocks told us that the mineral deposits around McArthur River probably formed below the sea bed and that ‘bacterial mats’ flourished on the sea floor,” Dr Logan said. “These mats lived on carbon dioxide and sulfide from the sediments, and very low levels of oxygen in the surrounding water.
“Our techniques are successful in detecting molecules of life from many millions of years ago. We can use the same technique to detect signs of life in even older rocks and potentially on material returned from Mars.”