Nuvvuagittuq greenstone belt, Nunavik

node · earth

A greenstone belt on the eastern shore of Hudson Bay in northern Quebec that carries the oldest and most contested claim in the whole record of life. In 2017 a group reported micrometre-scale haematite filaments and tubes in jasper interpreted as chemical precipitates from a seafloor hydrothermal vent, and argued they are the mineralised remains of iron-oxidising bacteria. The belt is at least about 3.77 billion years old on the conservative reading, and possibly as old as roughly 4.28 billion years on a disputed samarium–neodymium interpretation — which would make these the oldest traces of life by a very large margin. Two separate disputes therefore run at once, and they are independent of each other: whether the filaments are biological rather than abiotic mineral growths, and how old the host rocks actually are. The double uncertainty is a good illustration of why the origin of life is bracketed rather than dated.