The Hadean to Eoarchean Nuvvuagittuq Greenstone Belt

The Nuvvuagittuq greenstone belt is a volcano-sedimentary sequence located in northeastern Canada, mostly composed of metamorphosed mafic volcanic rocks and chemical sedimentary rocks such as banded iron formation (O’Neil et al., 2019). The Nuvvuagittuq greenstone belt includes some of the oldest, if not the oldest rocks, preserved on our planet. The exact age of the Nuvvuagittuq greenstone belt has been debated in the scientific community (Cates et al., 2013; O’Neil et al., 2019), but it is at least 3.75 billion-years-old (Cates and Mojzsis, 2007). However, variation in the isotope tracer 142Nd measured in the dominant volcanic rocks supports an age of 4.3 billion-yearsold, making them the oldest rocks known on Earth (O’Neil et al., 2008). The petrology and geochemistry of the Nuvvuagittuq rocks suggest it represents a remnant of hydrothermally altered oceanic crust, perhaps formed in short-lived subduction-like settings (O’Neil et al., 2019). This would represent the earliest evidence on Earth of a geodynamic regime resembling modern-day plate tectonic. The Nuvvuagittuq greenstone belt includes jasper-bearing banded iron formations displaying micrometer-scale hematite tubes and filaments with morphologies and mineral assemblages consistent with formation via biological activity (Dodd et al., 2017). This would constitute the earliest evidence of life on Earth.