Reunion, a French The island, in the western Indian Ocean, is like a marshmallow hovering over the trading end of a blowtorch. It sits atop one of Earth’s mantle plumes—a tower of superheated rock that rises from the deep mantle and flares the bases of tectonic plates, jigsaw pieces Who make up the ever changing face of the world. It’s hard to miss the plume’s effects: one of the island’s two massive volcanoes, aptly named piton de la fournaise, or “Peak of the Furnace”, is one of the most active volcanoes on the planet.
But Plum’s modern-day punch is nothing compared to its past.
About 65 million years ago, when the plume was under what is now India, a series of lava floods called the Deccan Traps succumbed. 1.5 million square kilometers of land—Texas, California and Montana to bury — in a mere 700,000 years, a geologic heartbeat. a giant asteroid strike There will be a coup for the dinosaurs, but the Deccan trap has long tarnished the picture of climate conditions dinosaur had to contend with.
In 2012, a team of geophysicists and seismologists mapped the plume, deploying a vast network of seismometers across the vast depths of the ocean floor of the Indian Ocean. Nearly a decade later, the team has revealed that Mantle is stranger than expected. The team reported in June nature geology That plum is not a simple column. Instead, a titanic mantle plume “tree” rises from the edges of the planet’s molten heart, with superheated branch-like structures appearing to grow diagonally. As these branches approach the crust, they begin to sprout small, vertically rising branches—super hot plumes that rise beneath known volcanic hot spots on the surface.
The discovery of this massive structure beneath Réunion almost coincides with a more recent discovery, Reported in November, which found additional structures in the plume under Africa. Taken together, the two findings represent an important scientific advance: they suggest that plumes may be more distinct, and have more detailed backstories than conventional models.
The root of the Reunion Tree, which researchers already knew from prior work, is probably an elemental object, perhaps almost as old as Earth itself. So it is possible that this hot tree has been increasing the canopy of its wings for billions of years. Assuming that more branches keep growing, scientists now have a window into Earth’s fiery future.
“By looking at the core-mantle boundary, you can probably predict where the oceans will open,” said study co-author carin siglocho. Researchers can also predict the land that will one day be destroyed. If the new models are accurate, then a few tens of millions of years from now, you won’t want to live in South Africa—or, perhaps, not on planet Earth at all.
in the 1960s, when the theory of plate tectonics was get approval fast, some geological features appeared to escape explanation. While the theory provided an explanation for questions that have long puzzled – where volcanoes appear, where land is born, where ocean basins are carved, where ancient crust is eroded away – it Nothing can explain quite like Hawaii.
Plate tectonics predicts that the boundaries of tectonic plates—where two plates collide, slide over or under each other, grind side-by-side, or break apart—are where most of the planet’s geologic fireworks can be found. The so-called Ring of Fire, the horseshoe-shaped region that marks the edges of many plates surrounding the Pacific Plate, is home to 75 percent One of the active volcanoes in the world.
But despite being nowhere near the plate boundary, Hawaii is an archipelago of giant volcanoes. Luihi, an active submarine volcano off the southeast coast of the Hawaiian Islands, is the youngest member of warped chain of volcanoes 6,000 kilometers long, one that can be traced to long-destroyed underwater volcanoes in the Pacific Northwest. This phenomenon, known as intraplate volcanism, emerged as a geologic aberration.
1963, Canadian geophysicist John Tuzo Wilson suggested that such volcanic chains lattice when a tectonic plate continuously flows over a stationary hot spot in the mantle – the scorching rock that makes up 84 percent of Earth’s volume. This creates a sequence of volcanoes that erupt, rise, then die as the plate moves away from the magmatic fuel source. 1971, American geophysicist William Jason Morgan as proposed That these hot spots were due to a pile of particularly hot material rising from the lower mantle.
In subsequent decades, geophysicists concluded that the plumes are about 200 °C hotter than the ambient mantle. When the plumes reach the base of the tectonic plates, their the heat melts their surroundings, making a lot of magma. Plumes also carry mantle material up from the depths of the Earth. This material melts at the lower pressures found away from the core, feeding additional magma into the crust. The combined supply of hot magma neatly explains a great number of Earth’s intraplate volcanoes.
Chains of volcanoes, also known as hot spot tracks, are difficult to explain without plumes. Hawaii is a marine example, but they can also be found on land: the Yellowstone supervolcano is the youngest member of the hot spot track, at least 17 million years old, that was cast 210,000 cubic kilometers of lava in the Pacific Northwest before blasting a giant volcanic cauldron From Oregon to Wyoming—One’s Undisputed Scar Tissue Incredible Mantle Plum.
Chemical evidence also suggests the existence of mantle plumes. There are two stable types of helium: Helium-3 and Helium-4. Helium-3 was trapped deep within the Earth during its formation and is certainly ancient. Many hot spot volcanoes, including Hawaii’s Kilauea, erupt lava with an abundance of the stuff. said that godfrey fittonA petrologist at the University of Edinburgh suggests that these volcanoes are mining mantle matter deep enough – and a plume is a reasonable explanation.
No eye has ever seen a plum directly; Their existence is predictable. But researchers have gathered a lot of evidence in their favor.
Seismic waves have provided the revelation verification. They are triggered by earthquakes that dive through the earth’s viscera before turning back toward the surface. As these waves travel, the speed and trajectory of the geological bodies they pass through change. Seismometers pick up on this information, and scientists use the data to try to figure out what’s hidden in that great abyss.
Seismic waves move more slowly through hot rock, and Study after Study have shown that they often slow down through tall formations that rise from the deep mantle and connect with volcanic hot spots on the surface.
Seismologists have also discovered two giant blobs of material—one beneath Africa, the other under the Pacific—that sit at the boundary between the mantle and the core. Deep-diving waves slow down as they both pass through the giant blob, suggesting they are hot colossi, together covering about 30 percent of the entire core-mantle boundary.