Northern Cordillera in the Pacific Ocean
5 thousand kilometers of mountains are hidden beneath the Pacific Ocean. Underwater volcanoes exist in all oceans. But these moved… several hundred kilometers.
A new one published on November 8th in Nature dives into the depths of the waves to show how Northeast mountain range formed between 43 and 83 million years ago — and its origins are a big surprise.
Seamounts are volcanoes, they exist in all oceans and are caused by “hot spots”, explains . These points are under the surface of the Earth, and in them heat accumulation melts the Earth’s mantlereleasing hot plumes in a tube-like outcrop.
Scientists did not believe that hot spots could move, so it was thought that the trail of underwater volcanoes resulted from the sliding of tectonic plates over an immobile hot spot. They were mistaken.
“Unlike most hotspots volcanics, which remain motionless in the mantle and create volcanic tracks as tectonic plates move over them, this study found that o hotspot responsible for the Northeast Ridge moved several hundred kilometers in the mantle over time“explains the geoscientist Hugo Olierookfrom Curtin University, Australia.
“It is thought that this type of movement of hotspots is common but difficult to prove and has only been demonstrated previously for some hotspots in the Pacific Ocean“, he also highlights.
If the hot spot of one of the mountain range’s ridges, the Kerguelen (responsible for creating the Indian Ocean’s vertical submarine scar, visible in the featured image) had remained fixed beneath the Indian Plate during this movement, then that ridge it would have moved north at the same rate as seafloor spreading. And that’s not what happened.
Between 83 and 66 million years ago, radioisotope dating suggests that the mountain range’s peaks were created at about half the rate of seafloor spreading.
This means that “the Kerguelen hot spot was not fixed under the Indian plate“, writes the international team of researchers, led by Qiang Jiang from China Petroleum University.
But why did the dot move at this rate? “The most likely scenario is that the mantle plume has been captured by the northward-migrating Indian-Antarctic spreading ridge and that plume materials have continually flowed toward the crest and erupted at the crest.”
About 66 million years ago, this plume was “turned off” when the ridge began to move too far away. Later, the plume was temporarily captured again, this time by the western spreading ridge. Until, 42 million years ago, the hot spot had already traced a vertical line that currently separates the Indian Ocean into east and west.
Curtin geoscientist Fred Jourdan explains the relevance of the study for investigations in this field: “By using high-precision dates, we can improve these models significantlywhich will allow us to better understand ancient continental movements.”
