The vast, remote landscapes of the global north are a treasure trove for geologists, holding some of the rarest and oldest rocks on our planet. A new study has now confirmed that a slice of crust in northern Canada is the oldest on record, solidifying the Arctic region’s reputation as a unique window into Earth’s fiery birth.
For years, scientists have flocked to sites across the Arctic to find remnants of the planet’s earliest history. The Acasta Gneiss Complex in Canada’s Northwest Territories holds rocks dating back 4.03 billion years. Not far away, in Greenland, the famed Isua Greenstone Belt contains rocks that are 3.7 to 3.8 billion years old and some of the earliest evidence of life.
But the ultimate prize has been the Nuvvuagittuq Greenstone Belt (NGB) on the shores of Hudson Bay in Quebec. For over a decade, its age has been a point of intense scientific debate. “For over 15 years, the scientific community has debated the age of volcanic rocks from northern Quebec,” recalls Jonathan O’Neil, an associate professor at the University of Ottawa and co-author of the new study. “Our previous research suggested that they could date back 4.3 billion years, but this wasn’t the consensus.” Now, a new study in Science has provided the strongest evidence yet, dating intrusive rocks within the NGB to an incredible 4.16 billion years old, confirming the belt contains the oldest rocks on Earth.
A Tale of Two Isotopic Systems
The controversy over the NGB’s age stemmed from the difficulty of dating its rocks, which are a type of basalt that lacks the zircon crystals typically used for reliable dating. Early studies that used a single dating method were contested, with some scientists arguing that later geological contamination skewed the results.
To resolve this, the research team analyzed a different type of rock within the belt—mafic intrusions that squeezed into the older volcanic layers. By using two independent dating methods on these younger intrusions, they could establish a definitive minimum age for the entire formation. “The different methods ‘gave exactly the same age,’” said O’Neil.
This dual-method approach was the key. The first system, based on the long-lived radioactive decay of a specific samarium isotope (Sm-147) to different neodymium isotopes (Nd-143) ratios, acts as a geological clock that has been ticking for billions of years. The second, and more crucial system, relies on the short-lived decay of Sm-146 isotope to Nd-142 isotope. Because the parent isotope, Sm-146, has a half-life of only 103 million years, it completely vanished within the first few hundred million years of Earth’s history. Its decay products are therefore a definitive timestamp from the Hadean eon.
The research team found that both systems independently pointed to the same conclusion. The long-lived system yielded an age of approximately 4.16 billion years, while the short-lived, Hadean-only system gave a statistically identical age of approximately 4.2 billion years. “The age agreement between both extant and extinct radiogenic systems… is compelling evidence for preservation of Hadean rocks in the NGB,” the study states. This powerful agreement rules out later geological disturbances and confirms the rocks’ primordial age.
A Window into a Primordial Planet
This confirmation is a landmark discovery, transforming the NGB into a globally unique site. “This confirmation positions the Nuvvuagittuq Belt as the only place on Earth where we find rocks formed during the Hadean eon, that is, the first 500 million years of our planet’s history,” says O’Neil.
The discovery does more than just award a new record. Because these ancient rocks intruded into an even older crust, the NGB provides a direct sample of Earth’s first continents. These findings suggest that the planet’s primitive crust was mafic—dark and dense—and formed directly from the mantle.
“Understanding these rocks is going back to the very origins of our planet. This allows us to better understand how the first continents were formed and to reconstruct the environment from which life could have emerged,” says O’Neil. This small, preserved piece of crust in northern Canada offers invaluable clues about the early tectonic activity that shaped our world and the harsh, ancient oceans that could have hosted the first life on Earth. The study confirms that the remote landscapes of the Arctic hold some of the most profound secrets to our planet’s origins, patiently waiting to be discovered.
Link to the study: : C. Sole et al. ,Evidence for Hadean mafic intrusions in the Nuvvuagittuq Greenstone Belt, Canada.Science388,1431-1435(2025).DOI:10.1126/science.ads8461