Dinosaur-era superstructure in the Pacific Ocean "still forming"

A team of scientists has uncovered the secrets of a gigantic underwater plateau in the Pacific Ocean that has been growing since the age of the dinosaurs. The plateau, called the Melanesian Border Plateau, is located east of the Solomon Islands and covers an area larger than the US state of Idaho.

The researchers used a combination of seismic data, rock samples, geochemical analysis and computer models to reconstruct the history and structure of the Melanesian Border Plateau. They found that the plateau is composed of different types of volcanic rocks, some of which are enriched in rare elements such as niobium and tantalum. These elements are used in high-tech applications such as smartphones, computers and medical devices.

The study also revealed that the plateau has a complex topography, with ridges, valleys, basins and faults. Some of these features may have been influenced by the movement of the tectonic plates, the climate changes and the sea level fluctuations over millions of years.

The researchers discovered that the plateau formed in four distinct phases, each with a different root cause and a different volcanic signature. The first phase occurred about 120 million years ago, during the Cretaceous period, when a massive outpour of lava created an array of seamounts on the ocean floor. This phase was triggered by the breakup of the supercontinent Gondwana, which split into Africa, South America, Australia, Antarctica and India.

The second phase took place between 56 million and 33.9 million years ago, when the Earth's outer rocky shell, called the lithosphere, passed over a volcanic region called the Arago hotspot. This phase produced more seamounts and some oceanic islands, which later eroded and submerged. This phase was caused by the subduction of the Pacific plate under the Australian plate, which created a volcanic arc.

The third phase happened between 23 million and 5 million years ago, during the Miocene epoch, when the same islands and seamounts were reactivated and new volcanoes were formed. This phase was related to the collision of the Australian plate with the Ontong Java Plateau, a massive oceanic plateau that formed from a single huge volcanic event. This phase also involved the Samoa hotspot, another volcanic region that is still creating new islands today.

The fourth phase, which is still ongoing, is driven by the mantle plume, a column of hot rock rising from the Earth's core. This phase causes new volcanic eruptions at the plateau, as the lithosphere has been deformed by the rollback of the Pacific plate beneath the Tonga trench.

The Melanesian Border Plateau is one of the many oceanic mid-plate superstructures that exist in the Pacific basin. These superstructures are different from the large igneous provinces that are created by a single massive volcanic event. They are also distinct from the mid-ocean ridges that are formed by the spreading of the oceanic plates.

The researchers hope that their findings will shed light on the origin and evolution of these superstructures, as well as their impact on the environment and the biodiversity of the ocean. They also hope that their study will inspire further exploration and research of the hidden wonders of the deep sea.