[ad_1]
Scientists have discovered exceptionally preserved microbial remains in some of the oldest rocks on Earth in Western Australia – a major breakthrough in the field, offering clues to the origin of life on Earth.
UNSW researchers have discovered the organic matter contained in stromatolites – fossilized microbial structures – from the former Dresser Formation in the Pilbara region of Western Australia.
Stromatolites have been biogenic since their discovery in the 1980s. However, despite strong textural evidence, this theory has not been proven for nearly four decades because scientists have not been able to demonstrate presence definitive remains of preserved organic matter – until today's publication in the prestigious journal Geology.
"It's an exciting discovery. For the first time, we are able to show the world that these stromatolites are irrefutable evidence of the very first life on Earth, "says Dr. Raphael Baumgartner, Principal Investigator at the Australian Center for Astrobiology. in the team of Professor Martin Van Kranendonk at UNSW.
According to Professor Van Kranendonk, this discovery is the closest the team has made to a "smoking gun" to prove the existence of such an ancient life.
"This represents a major breakthrough in our knowledge of these rocks, in the science of life investigations in general and, more specifically, in the search for life on Mars.We now have a new target and a new methodology for searching for traces of old life, "says Professor Van Kranendonk.
Deep drilling, looking closely
Since the formation of Dresser was discovered in the 1980s, scientists wondered if these structures were truly microbial and therefore the first signs of life.
"Unfortunately, there is a climate of mistrust of texture biosignatures in the world of research, so the origin of stromatolites in Dresser's training has been hotly debated," says Dr. Baumgartner.
"In this study, I spent a lot of time in the lab, using micro-analysis techniques to look very closely at the rock samples, to prove our theory once and for all."
The stromatolites of the Dresser formation usually come from the surface of the rock and are therefore very altered. For this study, scientists worked with samples taken deeper into the rock, under the weathering profile, where stromatolites are exceptionally well preserved.
"Examining drill core samples allowed us to visualize a perfect snapshot of ancient microbial life," says Dr. Baumgartner.
Using a variety of cutting-edge tools and advanced micro-analytical techniques, including high power electron microscopy, spectroscopy and isotopic analysis, Dr. Baumgartner analyzed the rocks.
He discovered that stromatolites are essentially composed of pyrite – a mineral also called "mad gold" – which contains organic matter.
"The organic matter we found preserved in stromatolite pyrite is exciting, we are looking at cohesive filaments and exceptionally preserved filaments that are typically remnants of microbial biofilms," says Dr. Baumgartner.
The researchers say that such remains had never been seen before in Dresser's training and that having seen the evidence under the microscope was incredibly exciting.
"I was quite surprised, we never expected to find this level of evidence before starting this project.I remember the night under the electron microscope where I finally discovered that I was looking at the remains of biofilm.I think it was around 11 pm, had this moment "eureka", and I stayed until three or four in the morning just for imaging and imaging because I was so I've completely lost track of time, "says Dr. Baumgartner.
Indices of the search for life on Mars
A little over two years ago, Dr. Baumgartner's colleague Tara Djokic, a UNSW doctoral candidate, discovered stromatolites in hot springs deposits in the same area of the state. Washington, delaying the microbial life on Earth by 580 million years.
"Tara's main discoveries have been these exceptional geyserite deposits that indicate that there have been geysers in this area, and therefore expulsions of fluid on an exposed surface," said Dr. Baumgartner.
"His study focused on the broader geological setting of the paleo-environment – providing support for the theory that life began on earth, rather than in the ocean – while my study really deepened the finer details of the stromatolite structures of the region. "
Scientists say the two studies help us answer a central question: where does humanity come from?
"Understanding where life might have emerged is really important to understanding our ancestry, and from there it could help us understand where life could have happened – for example, where it was started on others. planets, "says Dr. Baumgartner. .
Last month, scientists from NASA and the European Space Agency (ESA) spent a week in the Pilbara with Martin Van Kranendonk for specialized training in identifying signs of life in these same rocks old. It was the first time that Van Kranendonk shared knowledge of the region with a dedicated team of Mars specialists – a group comprising NASA's mission chiefs and ESA's Mars 2020.
"It is deeply gratifying that the ancient Australian rocks and our scientific know-how are making such a significant contribution to our search for extra-terrestrial life and the discovery of the secrets of Mars," said Professor Van Kranendonk.
Nano-porous pyrite and organic matter in 3.5 billion year old stromatolites record a prime lifespan, Geology
Please follow Astrobiology on Twitter.
[ad_2]
Source link