The splitting of the Earth’s mantle in two due to the Supercontinent Pangaea

Jakarta –

The Earth’s mantle was split by the Pacific Ring of Fire, an ancient rupture that marks the creation and destruction of the supercontinent Pangaea, according to a new study.

In one of these sections is the majority of the Earth’s land. Called the African continent, this region stretches from the east coast of Asia and Australia across Europe, Africa and the Atlantic to the west coast of North America.

The other part, the Pacific habitat, covers the Pacific Ocean. Below the African habitat, the Earth’s mantle is full of many elements and their variations (called isotopes), with a much greater diversity than in the Pacific habitat.

“This indicates the last two supercontinent cycles over the last billion years or so,” said study co-author Luc Doucet, a senior researcher in Earth and planetary science at Curtin University in Australia. , reported by Live Science.

During that time, there were two supercontinents: first, Rodinia, which was formed about 1.2 billion years ago and split up about 750 million years ago, and Pangaea, which was formed about 335 million years ago back and separated about 200 million years ago.

“What we’re seeing now is basically what happened during the transition from Rodinia to Pangea and then when Pangea broke up,” Doucet said.

These continents are united over what is today Africa. As the oceans move closer together, the oceanic crust moves beneath the continents, a process called subduction, sometimes dragging continental rock down with it. This drew elements and isotopes from the continental crust into the mantle beneath the growing supercontinent.

This geological conveyor belt continued in a slightly different form after the formation of the supercontinents. Oceanic crust on the margin of Rodinia, and later Pangaea, was subducted beneath continental crust, which in turn eroded some of the continental rock as tectonic plates rubbed against each other. each other

“This creates a funnel effect, concentrating everything under the supercontinent,” he said.

Even after Pangea broke up, these signs remained in the deep and shallow crust. In a follow-up to 2020 on magmas from the deep mantle, Doucet and Zheng-Xiang Li, professor emeritus at Curtin University, focused on shallow mantle magmas in the new study.

They studied the chemistry of 3,983 samples from mid-ocean ridges, where tectonic plates spread and magma from the shallow mantle flows and solidifies into volcanic rock, or basalt.

The researchers then used machine learning to compare the elemental and isotopic composition of basalts from around the world and from the same time period. As with magmas from deep mantle sources, they found that the shallow mantle is divided into African and Pacific regions.

The findings shed more light on the processes that connect the mantle and the surface. Why the supercontinent broke apart is not understood, but it is thought to contain hot mantle material rising from regions of the deep mantle known as large shear velocity regions (LLSVPs), or ‘blobs’ ‘ a costume. There are two blobs: one under the Pacific region and one under the Africa region.

“The combination of mantle fields reveals what is happening on the surface, but also what is happening at great depth,” said Doucet.

Understanding this process will help geologists determine where useful mantle materials can be concentrated, especially rare earth elements which are the metallic elements necessary for most of the technologies we use every day.

Plate tectonic processes are also responsible for cycling elements important for life, such as carbon and zinc, from the Earth’s interior to the surface, indicating that an active planet is important for the development and maintenance of life.

“Earth is the only planet with plate tectonics that we know of so far, and we want to understand how this whole system works and why it’s so special,” said Doucet.

(rns/rns)