Amazing stuff! Out of Africa or out of India?
It appears the German University of Technology in Oman has done similar research in Singhbhum Craton, India at least since March 2024, see Sedimentology and geochronology of Mesoarchean siliciclastic successions of the Singhbhum Craton, India and their implications
"Early in Earth’s history, the planet was covered in oceans. But the real hotspots were hydrothermal environments, where volcanic and tectonic activity provided the energy and nutrients needed for life to develop.
Over 3 billion years later, sedimentary rock formations known as cherts preserve traces of these ancient landscapes. Now, a new study presents evidence that they contain traces of life, too. ...
The findings provide the earliest evidence of life’s carbon signatures from a directly dated rock sample, reinforcing previous estimates of when life began."
From the significance and abstract:
"Significance
Kerogen, insoluble organic matter preserved in sediments, represents some of the earliest known terrestrial biosignatures which have provided important insights into the origin of life and planetary habitability.
Direct dating of these materials can be complicated by the lack of suitable geochronometers, instead relying on indirect constraints from, for example, the age of cross cutting lithologies.
Here, we report a 3.5-billion-year-old carbonaceous chert from eastern India containing what are interpreted to be contemporaneous tuffaceous zircons.
The chert exhibits micron-scale alternating layers of carbonaceous and siliceous materials.
δ13C isotope data of carbonaceous matter (CM) together with stratigraphic relationships indicate a biogenic origin of the kerogen marking this to our knowledge the oldest directly dated rock with a confirmed biosignature.
Abstract
Zircons interpreted to be of syn-volcanic origin recovered from the lower greenschist “black and white banded” Bhitardari chert, Eastern Iron Ore greenstone belt, Singhbhum craton, India, yield a 207Pb/206Pb zircon age of 3497 ± 5 Ma (n = 4; MSWD = 1.2).
This chert contains abundant carbonaceous matter (CM) that occurs in two textural modes:
1) ultrafine laminae distributed within the matrix and
2) graphite flakes in late quartz veins.
1) ultrafine laminae distributed within the matrix and
2) graphite flakes in late quartz veins.
Bulk δ13CCM of both modes in the Bhitardari chert yield a value of −30.9‰, which we interpret as reflecting a biogenic origin.
This represents the documentation of a directly dated, CM-bearing, Paleoarchean rock with δ13CCM diagnostic of biologic activity.
The observed isotopic compositions are consistent with the rise of relatively sophisticated metabolic mechanisms (e.g., Calvin cycle) by 3.5 Ga."
Direct dating of 3.5 Ga biogenic carbon in a microbial mat remnant, Singhbhum Craton, India (no public access)
Direct dating of 3.5 Ga biogenic carbon in a microbial mat remnant, Singhbhum Craton, India (This repository appears to provide access to the research article PDF file)
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