Evidence for microbial life in deep time: A geomicrobiological investigation using fluid inclusion studies

Fluid inclusions in evaporite-forming minerals are a suitable environment for extremophile life forms. Halite and gypsum from four different worldwide localities ranging in age from Permian to present time are used to investigate microbial life forms are trapped and preserved within fluid inclusions in these crystals. Previous investigations on this subject (REISER et alii, 1960; NORTON & GRANT, 1988; SCHUBERT et alii, 2009) proved the presence of halophilic bacteria inside halite crystals of Permian age by observing the growth of the organisms on external media. The bacteria were deemed to be the same age as the crystals, leading to the possibility that ancient microbes might be present in other evaporite deposits around the world. MC G ENITY et alii, (2000) proposed the possibility that microorganisms could survive in fluid inclusions as long as nutrients, such as carbon, which they require to survive can be trapped in the inclusions with them. However, it was more difficult to postulate how these nutrients could last for such a long time. They proposed that the halophilic organisms could remain dormant over geological time, until "awoken" upon collection. This finally suggested that studying fluid inclusions could be a way to observe ancient life and its environments.