Lakes in Argentina give evidence of life on Earth more than 3 billion years ago

(CNN) – Scientists have discovered a previously hidden ecosystem with an extensive system of lakes in the salt plains of Puna de Atacama, an arid plateau in Argentina. Stromatolite Giants, which could offer a glimpse of early life on Earth and perhaps even on Mars, according to new research.

Stromatolites are layered rocks created by the growth of blue-green algae, or cyanobacteria, through photosynthesis. According to NASA, These structures are considered among the oldest ecosystems on Earth and represent the oldest fossil evidence of life, at least on our planet 3.5 billion years.

“They certainly resemble some of the oldest macrofossils on our planet, and in a really rare type of environment on modern Earth,” he said. Brian Hynek, A professor in the Department of Geological Sciences at the University of Colorado Boulder, who helped document the ecosystem. “It’s a window into the distant past of what life was like 3.5 billion years ago on our planet.”

Ancient giant stromatolites were widespread in Earth’s Precambrian era, covering the early period from about 4.6 billion to 541 million years ago, but are now sparsely distributed around the world. The best developed areas are in the Bahamas and the Shark Bay region of Western Australia, according to the non-profit Nature Conservancy. Bush Heritage Australia.

Hynek said modern stromatolites are relatively small, while ancient stromatolites typically grow up to 20 feet (6 meters) long and 16 to 22 feet (5 to 7 meters) wide. Beneath the waters of the Puna de Atacama Lakes, newly discovered stromatolites are up to 15 feet (4.5 meters) wide and several feet high, according to a new publication from the institute. University of Colorado at Boulder.

Stromatolites also tend to grow in alkaline conditions, but the lake system at Puna de Atacama is acidic. The stromatolites found today are almost all carbonate rocks (made of limestone), but these structures are composed primarily of the minerals gypsum and halite (rock salt), Hynek said.

Hynek said it was unclear why the stromatolites were so large, but he speculated that the internal ecosystem remained intact for a long period of time, allowing them to grow unhindered.

More about eAncient stromatolites

Unlike modern stromatolites, ancient stromatolites grew during a period when the atmosphere lacked oxygen. Under these conditions, microbes present in stromatolites were used anoxygenic photosynthesis, Which do not need oxygen, to convert light energy into compounds that support living cells.

“It is amazing to find structures that could be biological in origin (produced by living organisms) at this unusual altitude,” he said in an email. Peter Fisher, a professor of marine sciences at the University of Connecticut who has studied stromatolites extensively. “The main problem with this discovery, whether biological or not, is that these form in the presence of oxygen (in the current atmosphere). Even 2.3 billion years ago there was no oxygen.

Although stromatolites exist in an oxygen-containing environment, HinEck said he believes the deeper layers of rock receive little oxygen and are actively formed by microbes using anoxygenic photosynthesis. This would make the structures similar to those found on ancient Earth.

Argentina’s lake system was initially discovered through satellite images in April 2022. (Photo: Brian Hynek).

Hynek discovered the lake system through satellite images in April 2022 when studying another lake in northwestern Argentina that contains smaller stromatolites with microbes that use anoxygenic photosynthesis.

“We’re not sure if microbes are actively involved in their growth (in the newly discovered stromatolites). We think they are,” said Hynek, who documented the initial observations with microbiologist Maria Farias, co-founder of environmental consultancy Punabio SA. “We’re still experimenting to try to figure that part out.” “There’s a lot of work to be done. “We just discovered them and have barely scratched the surface.”

Hynek and Farias were scheduled to present their findings on December 11 at this year’s Geophysical Union meeting in San Francisco, according to a press release.

A potential window into ancient Mars

If stromatolites are produced by microbes through anoxygenic photosynthesis, the discovery could provide insight into the possibility of life on ancient Mars, Hynek said.

“We have identified MMore than 600 lakesancient on Mars; Maybe there was an ocean. “So from the beginning it was very much like Earth.” Hynek added that Gypsum and halite mineralswhich are found in the stromatolites of Argentina, and are also found in salt deposits throughout Mars.

“If life evolved on Mars through photosynthesis, this is the thing that would happen We’ll be looking for stromatolite, “This is the thing we’re looking for,” said Hynek, who is also a research associate at the Laboratory for Atmospheric and Space Physics at the University of Colorado at Boulder.

“If we wanted to find any kind of fossils on Mars, this is our best guess as to what they would be, because they are the oldest in the terrestrial rock record.”

Hynek said he hopes to return to the lake soon to conduct more research on stromatolites.

“Stromatolites on Mars? A long shot, but who knows. So far there are no carbonates on Mars, but the search continues,” looking for possible signs of life, Fisher said.