On the eastern coast of Hudson Bay in Quebec, Canada, researchers have discovered the oldest crustal rocks on the planet, the age of which is at least 4.16 billion years. These are volcanic rocks from the Nuvvuagittuq Greenstone Belt, near the Inuit settlement of Inukjuak. About opening reportedReuters agency.
“These rocks and the Nuvvuagittuk zone are the only surviving evidence from Hadean times. They provide a unique window into the earliest history of our planet to better understand how the first crust was formed and what geodynamic processes were involved.”, – said the leader of the study, professor of geology at the University of Ottawa Jonathan O’Neill.
The scientists used two radioisotope dating methods based on the decay of samarium and neodymium, and both showed the same age of 4.16 billion years. The object of the study was the so-called “intrusions” – rocks formed from magma that penetrated deep into the earth, cooled and solidified. Probably, the very rocks into which this magma penetrated are even older – they can be up to 4.3 billion years old.
According to the researchers, the rocks from Nuvvuagittuk are basaltic in origin and have undergone changes under the influence of high temperatures and pressure. They probably formed when rain fell on the red-hot lava, cooling it and helping the crust to form. This moisture, according to scientists, was part of the original oceans.
“Since some of these rocks were also formed from sediments of ancient seawater, they can shed light on the composition and temperature of the first oceans and help understand the environment in which life on Earth could have originated.”, – added O’Neill.
Previously, rocks from the Northwest Territories of Canada were considered to be 4.03 billion years old. The absolute record for age is held by zircon crystals from Australia – they are 4.4 billion years old. However, unlike zircon, Nuvvuagittuku rocks are solid fragments of the earth’s crust that have preserved the traces of the first geological processes.
Scientists hope that the discovery will lead to a deeper study of the Hadean Eon, the oldest geological period spanning 4.5 to 4.03 billion years ago.
“Earth was definitely not a solid ball of molten lava throughout the Hadean Eon, as its name might suggest. Around 4.4 billion years ago, there was already a solid crust, probably mostly basaltic, covered by shallow and warm oceans. An atmosphere was also present – though not at all like it is now.”, – O’Neil clarified.
