Akilia

Geology

The rocks in question are part of a metamorphosed supracrustal sequence located at the south-western tip of the island. The sequence has been dated as no younger than 3.85 billion years old - that is, in the Hadean eon - based on the age of an igneous band that cuts the rock. The supracrustal sequence contains layers rich in iron and silica, which are variously interpreted as banded iron formation, chemical sediments from submarine hot springs, or hydrothermal vein deposits. Carbon in the rock, present as graphite, shows low levels of carbon-13, which may suggest an origin as isotopically light organic matter derived from living organisms. However, this interpretation is complicated because of high-grade metamorphism that affected the Akilia rocks after their formation. The sedimentary origin, age and the carbon content of the rocks have been questioned.

If the Akilia rocks do show evidence of life by 3.85 Ga, it would challenge models which suggest that Earth would not be hospitable to life at this time.