In the frozen rock layers of northern Canada, scientists have discovered the oldest rocks on Earth to date, with an age dating back to 4.16 billion years ago. This groundbreaking research was published in the journal “Science” on Thursday, June 26th.
Located on the eastern coast of Hudson Bay in Quebec, Canada, near the Inuit town of Inukjuak, lies a formation called the Nuvvuagittuq Greenstone Belt, characterized by dark and light green volcanic rocks with pink and black spots.
Researchers used two dating methods based on the radioactive decay of samarium and neodymium elements to determine that these rocks are 4.16 billion years old, belonging to the Hadean eon, a geological era named after the Greek underworld god, Hades, due to the harsh conditions of early Earth.
The rocks in the Nuvvuagittuq region are predominantly basalt, having undergone metamorphism from prolonged high-temperature and high-pressure processes. The rocks tested in the new study are referred to as intrusive rocks, indicating they solidified underground after magma infiltrated rock layers and cooled.
Scientists speculate that these leaf-shaped basalts formed during the initial stages of crust formation, preserving remnants of Earth’s earliest crust. Through chemical analysis, researchers hope to gain insight into the environmental conditions of the Hadean eon, a period that has been challenging to study due to the lack of physical remains.
Jonathan O’Neil, a geological professor at the University of Ottawa and lead researcher of the study, commented, “These rocks and the Nuvvuagittuq Greenstone Belt are the only known remnants from the Hadean eon, providing us with a unique perspective on how the original crust formed and relevant Earth dynamics.”
As these rocks could have formed in the early Earth when rainwater from primitive oceans evaporated and fell onto molten rocks, causing them to cool and solidify, O’Neil noted, “They can reveal the composition and temperatures of the earliest oceans, aiding in reconstructing the environment conducive to the origin of life on Earth.”
O’Neil mentioned that the previously known oldest rocks were found in the Northwest Territories of Canada and date back 4.03 billion years.
Currently, the rocks in the Nuvvuagittuq region are considered the oldest known rocks, although tiny zircon crystals found in western Australia have been dated even earlier, tracing back to 4.4 billion years ago.