Unveiling ancient ocean floor: A thrust in Earth's dynamic history
Scientists have found remnants of an ancient seabed beneath the Nazca Plate. The discovery, described in the journal "Science Advances," may explain the fastest spreading of the oceanic ridge in the world.
A team of geologists from the University of Maryland, led by Jingchuan Wang, used seismic data to identify ancient oceanic plates hidden deep in Earth's mantle beneath the Nazca Plate, adjacent to South America, and covering the southeastern part of the Pacific Ocean. As Science Alert explains, these ancient plates, dating back to the dinosaur era about 250 million years ago, may be key to understanding the rapid expansion of the East Pacific Rise.
Mysterious structure on the ocean floor
"Our discovery raises new questions regarding the impact of Earth's deep interior on the surface phenomena we observe, across vast distances and timescales," says Wang, quoted by ScienceAlert.
By analyzing the movement of seismic waves, scientists noticed an unusual structure in Earth's mantle, moving slower than expected. The mantle, a deep layer of Earth composed of hot silicate rocks, undergoes slow flows of matter over tens of millions of years. It has a thickness of about 2,900 kilometres and lies between the crust and the core. Importantly, the Earth's mantle plays a significant role in the processes related to the release of energy from Earth's interior.
In the region studied by Wang's team, the Nazca Plate subducts (slides) under South America, leading to the gradual uplifting of the Andes. However, their research revealed that material in this area descends at a rate half as fast as predicted, suggesting that the transition zone in the mantle may be slowing the movement of matter.
According to the scientists, this thickened zone is a fossilized remnant of an ancient seabed that sank into Earth's depths about 250 million years ago. Without completely melting, these fragments influence the formation of mantle plumes, which may be responsible for geological activity beneath the Easter Islands.
The research suggests that these anomalies deep within Earth may help explain the movements of the Nazca Plate in the history of our planet. "Thanks to this discovery, we can better understand how deep processes inside Earth shape its surface," adds Wang.
