Canada is the land of hockey, maple syrup, and a tendency to end every sentence with the word “eh” – it’s also home to the oldest rocks on Earth.
A new study, published in Science, confirmed that the oldest rocks on Earth are located in the Canadian province of Quebec as part of the Nuvvuagittuq Greenstone Belt. The rocks, dated to 4.16 billion years ago, were formed during the Hadean Eon, the oldest geologic eon in Earth’s history.
“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,” said Jonathan O’Neil, an associate professor in the Department of Earth and Environmental Sciences at the University of Ottawa, in a press release.
Read More: The Hidden Layers of Earth and Tectonic Plate Movements
Dating The Oldest Rocks on Earth
Earth is constantly remaking itself through processes like melting and recrystallization. These processes make it difficult to trace the early history of our planet as rocks are formed and reformed.
For this study, researchers first found these ancient rocks in 2017 near Nunavik, Quebec, and have been working on accurately dating them ever since. They combined both petrology and geochemistry to help reach their conclusion by figuring out when the rocks first crystallized.
Petrology looks at the origin, composition, and texture of the rocks, while geochemistry analyzes the rocks’ chemical elements. Once the data has been extracted from the rocks using these two methods, researchers then attempt to use that data to come to a radiometric date.
The data extraction for these rocks focused on the isotopes of two particular elements — samarium and neodymium. Isotopes decay over time, acting like a clock for scientists trying to date extremely old material. When the team studying the Nuvvuagittuq Belt rocks compared the radiometric dates of both sets of isotopes, they came back with the same result: the rocks are 4.16 billion years old.
What Is The Nuvvuagittuq Belt?
The Nuvvuagittuq Greenstone Belt is located in northeastern Canada and comprises a collection of volcanic and sedimentary rocks. The volcanic formations have been dated to 4.16 billion years old, which helps scientists conclude that the volcanic rocks must be even older.
But the date of the rocks themselves isn’t the only interesting part of the area. Many rock formations there represent a time before the Earth was formed by tectonic plate shifts. Instead, the formations at Nuvvuagittuq were created by a process known as hydrothermal alteration.
Hydrothermal alteration occurs when warm seawater is pushed into Earth’s crust and reacts with the rocks before returning to the ocean. Along with being the location of the oldest rocks on Earth, the Nuvvuagittuq Belt is also the earliest evidence of these pre-tectonic formations.
What Can We Learn From The Oldest Rocks on Earth?
Studying rocks from the beginning of Earth’s existence can provide a ton of insight into our planet. We can learn more about processes like hydrothermal alteration that helped form the early Earth. Additionally, we can better understand the geological environments that contributed to the formation of life, like the atmosphere and water temperatures.
“Understanding these rocks is going back to the very origins of our planet,” said O’Neil in the press release. “This allows us to better understand how the first continents were formed and to reconstruct the environment from which life could have emerged.”
Read More: Drilling Deep: How Far Have We Gone Under Earth's Crust?
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As the marketing coordinator at Discover Magazine, Stephanie Edwards interacts with readers across Discover's social media channels and writes digital content. Offline, she is a contract lecturer in English & Cultural Studies at Lakehead University, teaching courses on everything from professional communication to Taylor Swift, and received her graduate degrees in the same department from McMaster University. You can find more of her science writing in Lab Manager and her short fiction in anthologies and literary magazine across the horror genre.
