Moving ‘hotspot’ created world’s longest straight underwater mountain belt

Stretching 5000km along the Indian Ocean’s 90-degree east longitude and nearly matching the length of North America’s Rocky Mountains, the ridge offers crucial new insights into the movement of the Earth’s tectonic plates.

Co-author Dr Hugo Olierook from Curtin’s School of Earth and Planetary Sciences said high-precision dating of minerals extracted from the ridge shows it formed between 83 and 43 million years ago as a massive volcanic chain, with its oldest sections in the north, near India.

“Unlike most volcanic hotspots that remain stationary in the mantle and create volcanic trails as tectonic plates drift over them, this study found that the hotspot responsible for the Ninetyeast Ridge moved by several hundred kilometres within the mantle over time,” Dr Olierook said.

“This kind of hotspot movement is thought to be common but is hard to prove and has only previously been demonstrated for a few hotspots in the Pacific Ocean, making this the first documented case in the Indian Ocean.”

This discovery not only revises the estimated age and origin of the ridge but also helps scientists to create more accurate models of how Earth’s tectonic plates have shifted over millions of years.

Co-author Professor Fred Jourdan, from Curtin’s School of Earth and Planetary Sciences and the John de Laeter Centre, said precise dating techniques were vital to understanding Earth’s geological past.

“For years, rough age estimates of the Ninetyeast Ridge have been used to construct models of how Earth’s tectonic plates moved and reconfigured,” Professor Jourdan said.

“By using high-precision dating we can refine these models significantly, leading to better insights into ancient continental movements.”

A PhD student at Curtin’s School of Earth and Planetary Sciences at the time of the study, lead author Associate Professor Qiang Jiang from the China University of Petroleum said in order to better predict the occurrence of natural disasters such as earthquakes and volcanic eruptions, it was important to know precisely how the internal plumbing of the Earth works.

“Currently, this is far from being the case, so studies like this one are a major step in the right direction,” Associate Professor Jiang said.