New research from Curtin University has provided fresh insights into the formation of the Ninetyeast Ridge, the longest straight underwater mountain chain on Earth. The findings suggest that the ridge’s creation involved a unique process, contrasting with earlier beliefs.

The Ninetyeast Ridge stretches 5,000 kilometers along the 90-degree east longitude of the Indian Ocean. Its length is nearly identical to that of North America’s Rocky Mountains. This impressive geologic feature provides pivotal information on the shifting of Earth’s tectonic plates.

Dr. Hugo Olierook, co-author of the study from Curtin’s School of Earth and Planetary Sciences, shared that precise dating of minerals from the ridge point to its formation from 83 to 43 million years ago. This massive volcanic chain, with its oldest parts located near India in the north, offers a unique look into the Earth’s geologic past.

“Typically, volcanic hotspots remain stationary within the mantle, creating trails of volcanic activity as tectonic plates move above them,” Dr. Olierook explained. “However, our study suggests that the hotspot responsible for the Ninetyeast Ridge relocated by several hundred kilometers within the mantle over time.”

Though this type of hotspot movement is believed to be common, it’s challenging to prove. The Ninetyeast Ridge is the first documented case of this phenomenon in the Indian Ocean, with earlier evidence limited to a few hotspots in the Pacific Ocean.

This discovery not only redefines the estimated age and creation of the Ninetyeast Ridge but also enables scientists to improve models that depict the shifting of Earth’s tectonic plates over millions of years.

Co-author Professor Fred Jourdan, also from Curtin’s School of Earth and Planetary Sciences and the John de Laeter Centre, highlighted the importance of precise dating techniques in understanding Earth’s geologic history.

Professor Jourdan noted that previous models of tectonic plate movement and realignment were based on rough age estimates of the Ninetyeast Ridge. With high-precision dating, these models can be significantly refined, thereby improving our understanding of ancient continental shifts.

Associate Professor Qiang Jiang, the lead author from the China University of Petroleum and a PhD student at Curtin’s School of Earth and Planetary Sciences at the time of the study, emphasized the importance of understanding Earth’s internal dynamics to predict natural disasters like earthquakes and volcanic eruptions.

“Currently, our understanding of Earth’s internal workings is far from complete, making studies like this a significant step forward,” Associate Professor Jiang concluded.