Scientists say they’ve proven these Canadian rocks are the oldest on Earth

In 2008, a groundbreaking discovery was made by Canadian researchers led by McGill PhD student Jonathan O’Neil. They claimed to have found the world’s oldest rocks, formed 4.3 billion years ago in what is now northwestern Quebec. These rocks, located in the Nuvvuagittuq Greenstone Belt (NGB), offered a rare glimpse into Earth’s early history during its first eon, the Hadean, just a few hundred million years after the Earth’s formation.

However, the discovery faced controversy as some scientists argued that the rocks were merely mixtures of older and younger material, casting doubt on their ability to provide insights into the Earth’s ancient past. O’Neil and his team have now conducted a new analysis of rocks from the NGB, revealing that the newly studied rocks are at least 4.16 billion years old, confirming their Hadean origins.

Rocks, according to O’Neil, are like books to geologists, containing valuable chemical records of their formation and the environmental conditions at that time. With such ancient rocks, researchers have the opportunity to uncover new information about a time period for which there is very limited record.

The Hadean eon, characterized by a molten lava-covered Earth, was previously believed to have ended when the first rocks formed. The “golden spike” marking the end of the Hadean is located at the Acasta Gneiss formation in the Northwest Territories, dating back 4.03 billion years. Recent discoveries, including zircons formed 4.4 billion years ago in Australia, have challenged the notion that there were no rocks during the Hadean, expanding our understanding of Earth’s early history.

The NGB rocks, composed of pale basalt typically found on the ocean floor, have posed challenges in determining their age due to the absence of zircons. O’Neil and his team employed samarium-neodymium dating, a technique suitable for rocks older than four billion years, to establish the age of the rocks.

The controversy surrounding the age of the NGB rocks stemmed from discrepancies in dates obtained from different isotopic clocks. In the new analysis, both clocks aligned, providing a more convincing age of 4.16 billion years for the rocks. While some scientists remain skeptical, others, like Martin Bizzarro and Graham Pearson, acknowledge the thoroughness of O’Neil’s team’s study.

The new data not only solidifies the rocks’ Hadean origins but also paves the way for further discoveries related to ocean chemistry, plate tectonics, and early signs of life. O’Neil hopes that the age of these rocks will inspire confidence in the scientific community, allowing for a deeper understanding of Earth’s ancient past.