Studying satellite images, scientists accidentally stumble upon a ‘land that time forgot’

Studying satellite images of Argentina’s Puna de Atacama desert, CU Boulder geologist Brian Hynek noticed something odd. In the monotonous gray of salt and sand flats, he noticed a number of green and blue spots of unknown origin.

Puna de Atacama is a desert with a high plateau more than 3000 meters above sea level, surrounded by even higher peaks of Andean mountain range. It is among the driest environments on Earth. Here, rain falls rarely, if ever, and the sunlight shines relentlessly, creating an environment in which few animals or plants can survive. So it is unlikely that the spots are any vegetation or man-made.

Together with Maria Farias, a microbiologist and co-founder of the environmental consultancy PUNA.BIO, Hynek decided to visit the area to solve this mystery.

After hours of driving on dirt roads and walking through mud, they discovered that the spots are a network of twelve lagoons, housing a unique community of microbes that form giant rock mounds in the shallow waters.

Hynek’s preliminary observations suggest that these communities may resemble stromatolites, the earliest signs of life that existed on Earth more than 3.5 billion years ago.

“This lagoon may be one of the best modern examples of the earliest signs of life on Earth,” explains Hinek, a professor in the Laboratory for Atmospheric and Space Physics (LASP) and the Department of Geological Sciences. “It’s unlike anything I’ve ever seen, or indeed anything any scientist has ever seen.”

Stromatolites generally refer to a set of microbial communities that are associated with rock layers. They exist on Earth today, including off the coast of the Bahamas and Australia, but modern stromatolites tend to be relatively small. They also grow passively by capturing grains of sand and other debris floating in the ocean.

Ancient stromatolites, in contrast, could stretch up to 6 meters high. They actively extract calcium and carbon dioxide from the surrounding water, causing minerals to precipitate around them.

The mounds in the Atacama Lagoons looked much more like some of these Archaean communities than anything alive on Earth today. They are large, about 4 meters wide and several meters high, and show a layered structure ranging in color from brown to pink to green. The colors reflect different microbial communities, from brown microbes that live without oxygen, to pink salt-adapted microorganisms, to green photoautotrophic cyanobacteria that form the outer layer of the stromatolite.

Why they formed in this harsh place is not clear. The lagoon’s environment may resemble conditions on ancient Earth, Hynek said — the waters are salty and acidic and, because of the high altitude, exposed to severe levels of solar radiation, allowing only specialized microscopic life to survive.

The researchers hope to return to the lagoon soon to confirm their initial results. Hynek called finding this primal environment “the biggest eureka moment I’ve ever had in my life. It’s just amazing that you can still find such undocumented things on our planet.”

However, scientists may be running out of time. A company outside Argentina has already leased the area to mine lithium and other rare elements deposited by the evaporating waters.

“This whole unique ecosystem could be gone in a few years,” Hinek said. “Hopefully we can protect some of these sites, or at least describe in detail what’s there, before it’s gone or disrupted forever.”

Additional materials and interviews provided by University of Colorado Boulder.

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