OREANDA-NEWS Scientists from the University of Ottawa, Carleton University and University College London have refuted the opinion that graphite found in ancient rocks of the Saglek-Hebron geological complex in Nunatsiavut (northern Labrador) arose as a result of the activity of the oldest living organisms. The results of the study are published in the journal Nature Communications.

Graphite found in the sedimentary rocks of Saglek Hebron was previously considered the oldest traces of life on Earth. However, the isotopic signatures and other geochemical characteristics of graphite studied in the new study indicate its abiotic origin. This means that graphite in these rocks was formed without the participation of biological processes.

The study used petrographic, geochemical and spectroscopic methods to analyze three graphite samples collected in Nunatsiavut. Petrological characterization was carried out at the University of Ottawa, and spectroscopic carbon analysis was carried out at University College London. These methods made it possible to study in detail the structure and composition of graphite, which helped to draw conclusions about its origin.

The results of the study showed that graphite found in rocks about 3.9 billion years old was probably formed as a result of processes associated with metamorphic liquids at high temperatures (more than 500 degrees Celsius), and not due to the activity of single-celled microorganisms.

Additional analysis also showed that the degree of crystallization of graphite correlates with the level of metamorphism of rocks. This confirms that metamorphism played a key role in the transformation of carbonaceous materials preserved in ancient rocks of the Saglek-Hebron complex.