Earth’s inner secrets revealed in oldest rocks found on ocean floor
- Rocks from 2.8 billion years ago found in collection dredged up by US vessel in 2000, international team of geologists says in recent paper
- Ancient rocks on relatively young ocean floor could upend long-held ideas about Earth’s mantle, study lead notes
The rocks, dredged up from the bottom of the Indian Ocean by a US research vessel more than two decades ago, were recently analysed at a geology lab in Beijing.
Researchers found the rocks not only dated back 2.8 billion years to what is called the “Archaean” era – derived from archaios, the Greek word for “ancient”- but were surprisingly of continental origin.
The find sheds new light on how the Earth’s interior works, the team said in a recently published paper in peer-reviewed journal Science Advances.
While the oldest continental rocks are over 4 billion years old, rocks that make up the ocean floor are much younger – typically less than 200 million years old, said lead author Liu Chuanzhou, a marine geologist at the Chinese Academy of Sciences.