A team of Canadian and French researchers has just confirmed that northern Quebec is home to the oldest known rocks on earth, dating from 4.16 billion years.
Directed by Jonathan O’Neil, associate professor in the Department of Earth and Environment Sciences at the University of Ottawa, this major discovery is the fruit of a collaboration between Christian Sole (who ended his master’s degree at the University of Ottawa in 2021), Hanika Rizo (Professor at Carleton University), Jean-Louis Paquette (researcher at the National Center for Scientific Research (CNRS) Magmas and volcanoes from Clermont-Auvergne University, France, now died), David Benn (former baccalaureate student in Uottawa) and Jeleli Plakholm (former baccalaureate student at Carleton University).
Professor O’Neil, who supervised the original study, explains: “The results obtained during the mastery of Christian Sole were extremely promising. We continued research after the finalization of his mastery to confirm the exceptional age of these rocks. »»
An exceptional geological site
The samples were collected in 2017 near the municipality of Inukjuak, in Nunavik, as part of the Master’s project by Christian Sole. After preliminary analyzes, additional work was carried out at the University of Ottawa and at Carleton University in order to confirm the seniority of the rocks.
“For more than 15 years, the scientific community has debated the age of northern volcanic rocks. Our previous research suggested that they could date from 4.3 billion years, but it was not a consensus, “said Professor O’Neil.
A window on primitive earth
The current study demonstrates that intrusive rocks crossing these volcanic formations are aged 4.16 billion years, which confirms that volcanic rocks are necessarily older, and therefore that this region of the North Canadian is indeed the oldest known land rocks. “This confirmation positions the Nuvvuactuq belt as the only place on earth where there are rocks formed during the Hadéen, that is during the first 500 million years in the history of our planet,” said Professor O’Neil.
To establish the age of these rocks, researchers combined petrology and geochemistry and employee two methods of radiometric dating using different isotopes of samarium and neodymium elements as two independent chronometers giving the same age of 4.16 billion years. This advance offers a unique window on primitive earth. “Understanding these rocks is going back to the very beginnings of our planet. This helps us to better understand how the first continents were formed and to reconstruct the environment where life could have emerged, ”concludes Professor O’Neil.
For more information, see the study published in the newspaper ” Science “, Entitled” Evidence for Hadean mafic intrusions in the Nuvvuagittuq Greenstone Belt, Canada».
