Microbes 830 million years old were discovered in the Australian halite. They may be alive
What is hidden in the ancient halite? Credit: Schreder-Gomes et al. (2022), Geology.
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Halite mineral is actually a common salt, ie sodium chloride, in the form of often enchanting cubic crystals. In addition to aesthetic pleasure and salt, halite crystals can offer remarkable paleontological discoveries. They represent a probe into ancient times and contain a lot of interesting information about the environment in which they originated.
Geologist Sara Schreder-Gomes of West Virginia University and her team studied samples taken in 1997 from the Australian Browne Formation, which comes from the younger ancient Highlands (Neoproterozoic). They discovered a lot of halite in them, which testifies to the nature of the environment at that time. Today it is a wasteland, but in the younger ancient mountains there was the sea.
The researchers used exclusively non-invasive optical methods to study the halite, leaving the halite crystals intact, including what was inside. Using optical and ultraviolet petrographic microscopy, they identified halite crystals and then examined in detail the inclusions that they thought should be microbes.
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Sara Schreder-Gomes. Credit: St. Norbert College.
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For similar finds from ancient times, the question is usually whether they are fossils of organisms or not. Schreder-Gomes and her colleagues discovered objects that match microbes in size, shape, and fluorescence in ultraviolet light. In this case, they should be 830 million years old, dating back to about 100 million years before the Earth froze in the “Snowball” period.
The researchers emphasize that the detailed results of UV fluorescence analyzes are very interesting. Some objects show fluorescence that corresponds to decomposing organic matter. And there are also objects whose fluorescence corresponds to the organic material of living organisms. Schreder-Gomesova et al. they conclude that it could be microbes that are still alive.
Sounds unbelievable. And it is definitely necessary to take it in stride. The authors of the study admit that it is not yet very clear about the survival of microorganisms on a geological time scale. On the other hand, in the past, living microbes have been obtained from a 250-million-year-old halite, or from the beginning of the Mesozoic. So the idea that we will be able to revive ancient mountain microbes from halite is not so unrealistic.
As we know, the long-term survival of microbes in geological material is crucial to how much radiation they are exposed to. Radioactive radiation gradually destroys organic matter.
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Logo. Kredit: West Virginia University.
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If the Halne formation was largely spared the adverse effects of radiation, then there is a chance that there could indeed be something viable.
At the same time, Brown’s research on halite formation is being closely watched by astrobiologists searching for traces of life on Mars. There are similar rocks on the Red Planet in which we could search for ancient Martian organisms in a similar way.
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