The Nuvvuagittuq Greenstone Belt: A Glimpse of Earth’s Earliest Crust

Geologic processing of Earth’s surface has removed most of the evidence concerning the nature of Earth’s first crust and leaving the first 800 million years of Earth’s history almost devoid of rock samples. This greatly hiders our ability to understand how and when the primitive terrestrial crust formed. The Nuvvuagittuq greenstone belt in the Northeastern Superior Province of Canada offers a unique opportunity to unravel the early geological processes that shaped the Earth shortly after its formation. The exact age of the Nuvvuagittuq greenstone belt is debated. It is at least 3.77 billion years old, but 146Sm–142Nd isotopic evidence points to n Hadean age of about 4.3 billion years, which would make it the oldest preserved crustal terrane on Earth. The composition of the mafic metavolcanic rocks from the Nuvvuagittuq belt suggests that it represents a piece of oceanic crust hydrothermally altered by seawater, perhaps formed in a short-lived subduction initiation setting. Some features of the chemical sedimentary rocks preserved in Nuvvuagittuq belt also suggest that it could have preserved the remains of some of the earliest life on Earth. The Nuvvuagittuq belt therefore provides a glimpse of Earth’s earliest crust and can help us shed light on the earliest geological processes operating on our planet.