Researchers have discovered organic molecules trapped in incredible ancient rock formations in Australia, revealing what they say is the first detailed evidence of early chemical constituents that could take into account the life forms of Earth’s predominant microorganisms.
The discovery, made in the -.- billion-year-old dresser formation of Pilbara Craton in Western Australia, adds to the important part of research focusing on ancient life in this part of the world – representing only one of the two natural, open deposits. Land on Earth back to Archean Ion.
In recent years, the hydrothermal stock of dresser formation has turned into frequent signs of what appears to be the most ancient life on Earth, scientists say. Billions of years ago, “definitive evidence” of microbial biosignature was discovered.
Now, in a new study, German researchers have discovered traces of specific chemistry that could have enabled the existence of such primitive organisms.
“In this area, barots are directly associated with fossilized microbial mats, and when freshly scratched, they smell like rotten eggs,” explains Helg Miabek, a geologist at the University of Cologne in Germany.
“Thus, we suspect that it contains organic matter that may serve as a nutrient for early microbial life.”
Bright rock from dresser composition. (Helg Miabach)
While scientists have long speculated about how organic molecules may act as substrates for preferably microorganisms and their metabolic processes, the direct evidence has largely proved elusive.
To investigate, Meebach and fellow researchers examined the contents of barot from a dresser formation, in which a chemically stable mineral is able to protect the liquids and gases inside the rock for billions of years.
Using a range of techniques to analyze barite samples, including gas chromatography-mass spectrometry, microthermometry, and static isotope analysis, the researchers found that they are “known or hypothesized organic variables with consistent metabolism.
These included organic compounds acetic acid and methanethyl, which, in addition to numerous gases, including hydrogen sulfide, may have biotic or abiotic origin.
(Miabach et al., Nature Communications, 2021)
Above: Bright rock indicates close attachment of stromatolites.
While it may be impossible to confirm the exact links, the close proximity of the contents of Barate Rock and its associated organic aggression suggests that primitive chemicals, once contained within hydrothermal liquids, may affect primal microbial communities.
“Indeed, many of the compounds found in the inclusion of Bright-Hosted Fluid પૂ would have provided the ideal substrates for sulfur-based and methanogenic microorganisms previously proposed as players in the dresser environment,” the researchers wrote in their study.
In addition to chemicals that can act as nutrients or substrates, other compounds found in the inclusions can serve as ‘building blocks’ for various carbon-based chemical reactions – processes that produce kickstart sources, causing kickstart microbial metabolism. Like lipids, they can be broken down by life-forms.
“In other words, the essential complex of the proposed complex agent, methyl thioacetate, in the emergence of life, was available in the dresser environment,” the team explains.
“They would have delivered building blocks for chemotatrophic carbon fixation and, thus, the entry of carbon into the biomass.”
These findings are reported Nature Communications.
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