A recent study in Greenland has uncovered a 3.7-billion-year-old record of Earth’s magnetic field. The study, conducted by the University of Oxford and MIT, found an ancient sequence of iron-containing rocks, demonstrating that Earth’s ancient magnetic field was as strong billions of years ago as it is in 2024.
Researchers have found rocks dating from 3.7 billion years ago, which show the magnetic field strength of at least 15 microtesla. These rocks were found in the Isua Greenstone Belt in southwest Greenland.
The findings have been published in the Journal of Geophysical Research. The study’s resultsprovide the oldest estimate of the strength of Earth’s magnetic field obtained from whole rock samples.
“Extracting reliable records from rocks this old is extremely challenging, and it was really exciting to see primary magnetic signals begin to emerge when we analyzed these samples in the lab. This is a really important step forward as we try and determine the role of the ancient magnetic field when life on Earth was first emerging,” explained Professor Claire Nichols, Lead Researcher Professor at the Department of Earth Sciences, University of Oxford.
The Isua Greenstone Belt is located near the Nuuk capital region and comprises many different lithologies and rock types.