[4] In March 2017, a published report gave evidence for fossils of microorganisms in these rocks, which would be the oldest trace of life yet discovered on Earth.

In 2012 samarium–neodymium dating and neodymium isotope fractionation was used to establish an age of 4321 Ma for the Nuvvuagittuq Greenstone Belt.

[3] This was accomplished by dating intruding gabbros and measuring neodymium isotope fractionation in less-deformed members of the Ujaraaluk unit.

The cummingtonite amphibolites range from garnet-rich to garnet-poor and are interpreted to be highly metamorphosed volcano-sedimentary rocks.

[1] This period caused significant foliation and meter-scale folding in the faux-amphibolite and banded iron formations.

[8] It has been suggested that Algoma-type iron deposits can precipitate due to bacterial activity in an anoxic environment, as would be found in the very early Earth.

[10] These iron formations may be one of the oldest fingerprints of life, indicating that there may have been biological activity at the time that the NGB was being formed.

The structures seen are interpreted as hematite tubes, and filaments, similar in morphology and size to those produced today by bacteria living in subsea hydrothermal vents.

Collectively these multiple observations led the authors to conclude that they were produced by "biological activity" more than 3.77 billion years ago.

[13] A 2022 paper added that large (up to 1 cm), complex structures were present, with a central stem and parallel side branches, and ellipsoids alongside the tubules and filaments.

[14] In respect of having 'some of the oldest, if not the oldest, rocks on Earth, with potentially earliest traces of life', the International Union of Geological Sciences (IUGS) included the 'Hadean to Eoarchean Nuvvuagittuq greenstone belt' in its assemblage of 100 'geological heritage sites' around the world in a listing published in October 2022.