Home Science Environment Australian 3 Billion-Year-Old Hot Spring Tells of Earliest Signs of Life

Australian 3 Billion-Year-Old Hot Spring Tells of Earliest Signs of Life

Fossils discovered by UNSW scientists in 3.48 billion-year-old hot spring deposits in the Pilbara region of Western Australia have pushed back by 580 million years the earliest known existence of microbial life on land.

Previously, the world’s oldest evidence for microbial life on land came from 2.7- 2.9 billion-year-old deposits in South Africa containing organic matter-rich ancient soils.

Spherical bubbles preserved in 3.48 billion-year-old rocks in the Dresser Formation in the Pilbara Craton in Western Australia provide evidence for early life having lived in ancient hot springs on land. (Image: UNSW)

Study first author UNSW PhD candidate Tara Djokic said in a statement:

UNSW PhD student Tara Djokic in the Dresser Formation in the Pilbara Craton of Western Australia. (Image: Dale Anderson)

Scientists are considering two hypotheses regarding the origin of life. Either that it began in deep sea hydrothermal vents, or alternatively that it began on land in a version of Charles Darwin’s “warm little pond.” Djokic added:

The study, by Djokic and professors Martin Van Kranendonk, Malcolm Walter, and Colin Ward of UNSW Sydney, and Professor Kathleen Campbell of the University of Auckland, is published in the journal Nature Communications.

The researchers studied exceptionally well-preserved deposits that are approximately 3.5 billion years old in the ancient Dresser Formation in the Pilbara Craton of Western Australia.

Tara Djokic
Tara Djokic and Professor Martin Van Kranendonk in the Pilbara in Western Australia. (Image: Kathy Campbell)

They interpreted that the deposits were formed on land, not in the ocean, by identifying the presence of geyserite — a mineral deposit formed from near boiling-temperature, silica-rich fluids that are only found in a terrestrial hot spring environment. Previously, the oldest known geyserite had been identified from rocks about 400 million years old.

Ridges in the ancient Dresser Formation in the Pilbara Craton of Western Australia that preserve ancient stromatolites and hot spring deposits. (Image: Kathleen Campbell)

Within the Pilbara hotspring deposits, the researchers also discovered stromatolites — layered rock structures created by communities of ancient microbes.

And there were other signs of early life in the deposits as well, including fossilised micro-stromatolites, microbial palisade texture, and well-preserved bubbles that are inferred to have been trapped in a sticky substance (microbial) to preserve the bubble shape.

A microscopic image of geyserite textures from the ancient Dresser Formation in the Pilbara Craton in Western Australia. This shows that surface hot spring deposits once existed there 3.48 billion years ago. (Image: UNSW)

Professor Van Kranendonk, Director of the Australian Centre for Astrobiology and head of the UNSW school of Biological, Earth, and Environmental Sciences, said:

A modern-day geyser erupting at Geysir Hot Springs in Iceland. (Image: Tara Djokic)

In September 2016, Professor Kranendonk was part of an international team that found what is possibly the oldest evidence of life on Earth — 3.7 billion-year-old fossil stromatolites in Greenland deposits that were laid down in a shallow sea. He has also given geological advice to NASA on where to land the rover on the 2020 Mars Exploration Mission.

Professor Martin Van Kranendonk and Tara Djokic at Lake Rotokawa in New Zealand studying modern hot springs. (Image: Kathleen Campbell)

Professor Walter, founding director of the Australian Centre for Astrobiology, said:

This article by DEBORAH SMITH was provided by: UNSW

[Note: Materials may be edited for content and length.]

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