An astonishing discovery has just revealed a potential new source for understanding life on ancient Earth.
A team of geologists have just discovered tiny remnants of prokaryotic life and algae – trapped inside halite crystals dating back 830 million years.
Halite is sodium chloride, also known as rock salt, and the discovery indicates that this natural mineral could be a previously untapped resource for studying ancient saltwater environments.
Moreover, the organisms trapped in it might still be alive.
The extraordinary study also has implications for the search for ancient life, not only on Earth, but in extraterrestrial environments, such as Marswhere Large salt deposits They have been identified as evidence of ancient and extensive liquid water reservoirs.
Living things don’t look what you might expect. Ancient microfossils have been found compressed in rock formations, such as shale, that date back billions of years. Salt is not able to preserve organic matter in the same way.
Alternatively, when crystals form in the saltwater environment, small amounts of liquid can be trapped inside. This is called liquid impuritieswhich is the remains of the mother water from which halite crystallized.
Scientists have also found microorganisms that live in both modern and modern environments where halite forms. These environments are highly saline. However, microorganisms such as bacteriaand fungi and algae They were all found thriving in them.
In addition, microorganisms have been documented in fluid inclusions in gypsum and halite, mostly modern or modern, with a handful going back to antiquity. However, the method of identifying these ancient creatures left some doubt as to whether they were the same age as halite.
“Therefore, there is still a question among microbiologists,” Team Books It was led by geologist Sarah Schrader-Gomez of West Virginia University. “What are the oldest chemical sedimentary rocks containing prokaryotic and eukaryotic microorganisms from the sedimentary environment?”
Central Australia is now a desert, but was once an ancient salt sea. The brown formation It is a well-dated and distinct stratigraphic unit from Central Australia, dating back to the Neolithic era. They include extensive halite, indicative of a paleo marine environment.
Using a core sample of Brown Formation extracted by the Western Australian Geological Survey in 1997, Schrader-Gomes and colleagues were able to conduct investigations of unaltered neproterozoic halite using non-invasive optical methods. This left the halite intact. Which means, importantly, that anything inside had to be trapped by the time the crystals formed.
They used ultraviolet lithography and transmitted light, first at low magnification to identify halite crystals, and then magnifications up to 2,000-fold to study fluid inclusions in them.
Inside, they found organic solids and liquids, compatible with prokaryotic and eukaryotic cells, based on their size, shape and ultraviolet flash.
The radiance range was also interesting. Some samples showed colors consistent with organic decomposition, while others showed the same fluorescence of modern organisms, suggesting, the researchers said, of unaltered organic matter.
The researchers note that it is possible that some organisms are still alive. The fluid contents can serve as micro-habitats where small colonies thrive. Live prokaryotes have been extracted from halite dating back 250 million years. Why not 830 million?
“The possible survival of microorganisms on geological time scales is not fully understood,” Researchers wrote.
“It has been suggested that radiation would destroy organic matter over long periods of time, however Nicastro et al. (2002) found that the 250 million-year-old buried halite was exposed to only trace amounts of radiation. In addition, microorganisms may survive in fluid inclusions via metabolic changes, including surviving starvation and cyst stages, and coexisting with organic compounds or dead cells that can act as food sources.”
This certainly has implications for Mars, the researchers said, where deposits with similar compositions to Brown’s can be found. Their research shows how these organisms can be identified without destroying or disrupting specimens, which could give us a new set of tools to learn about them — and to better understand Earth’s history, too.
“Visual examination should be considered an essential step in any study of biosignatures in ancient rocks. It allows knowledge of the geological context of microorganisms prior to further chemical or biological analyzes…and provides a target for such analyses,” Team Books.
“Palaeochemical deposits, both terrestrial and of extraterrestrial origin, should be considered as potential hosts for ancient microorganisms and organic compounds.”
The search was published in geology.
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