[PNAS]. 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.
- Direct dating of 3.5 Ga biogenic carbon in a microbial mat remnant, Singhbhum Craton, India, PubMed
- Direct dating of 3.5 Ga biogenic carbon in a microbial mat remnant, Singhbhum Craton, India, PNAS
Astrobiology,
