Latest news with #SolidEarth
Yahoo
24-04-2025
- Science
- Yahoo
Scientists Spotted Signs of a Hidden Structure Inside Earth's Core
While most of us take the ground beneath our feet for granted, written within its complex layers, like the pages of a book, is Earth's history. Our history. Research shows there are little-known chapters in that history, deep within Earth's past. In fact, Earth's inner core appears to have another even more inner core within it. "Traditionally we've been taught the Earth has four main layers: the crust, the mantle, the outer core and the inner core," Australian National University geophysicist Joanne Stephenson explained in 2021. Our knowledge of what lies beneath Earth's crust has been inferred mostly from what volcanoes have divulged and what seismic waves have whispered. From these indirect observations, scientists have calculated that the scorchingly hot inner core, with temperatures surpassing 5,000 degrees Celsius (9,000 Fahrenheit), makes up only 1 percent of Earth's total volume. But a few years ago, Stephenson and colleagues found evidence Earth's inner core may actually have two distinct layers. "It's very exciting – and might mean we have to re-write the textbooks!" Stephenson explained at the time. The team used a search algorithm to trawl through and match thousands of models of the inner core with observed data across many decades about how long seismic waves take to travel through Earth, gathered by the International Seismological Centre. Differences in seismic wave paths through layers of Earth. (Stephenson et al., Journal of Geophysical Research: Solid Earth, 2021) So what's down there? The team looked at some models of the inner core's anisotropy – how differences in the make-up of its material alters the properties of seismic waves – and found some were more likely than others. While some models suggest the material of the inner core channels seismic waves faster parallel to the equator, others indicate the mix of materials allows for faster waves more parallel to Earth's rotational axis. Even then, there are arguments about the exact degree of difference at certain angles. The study here didn't show much variation with depth in the inner core, but it did find there was a change in the slow direction to a 54-degree angle, with the faster direction of waves running parallel to the axis. "We found evidence that may indicate a change in the structure of iron, which suggests perhaps two separate cooling events in Earth's history," Stephenson said. "The details of this big event are still a bit of a mystery, but we've added another piece of the puzzle when it comes to our knowledge of the Earth's inner core." These findings may explain why some experimental evidence has been inconsistent with our current models of Earth's structure. The presence of an innermost layer has been suspected before, with hints that iron crystals that compose the inner core have different structural alignments. "We are limited by the distribution of global earthquakes and receivers, especially at polar antipodes," the team writes in their paper, explaining the missing data decreases the certainty of their conclusions. But their conclusions align with other studies on the anisotropy of the innermost inner core. Future research may fill in some of these data gaps and allow scientists to corroborate or contradict their findings, and hopefully translate more stories written within this early layer of Earth's history. This research was published in the Journal of Geophysical Research. An earlier version of this article was published in March 2021. 'Bone Collector' Caterpillar Wears Dead Bugs to Steal Prey From Spiders 113 Million-Year-Old 'Hell Ant' Discovery Is Oldest Ever Found Most Bees Nest in The Ground. Offering Rocks And Gravel Is a Simple Way to Help Them Thrive.
Yahoo
06-02-2025
- Science
- Yahoo
Ocean plate from time of Pangaea is now being torn apart under Iraq and Iran
When you buy through links on our articles, Future and its syndication partners may earn a commission. A long-lost oceanic plate is diving deep into the mantle, dragging down the crust above, researchers say. However, the plate is also tearing apart below the Zagros Mountains in Iraq as it plunges downward, taking some of the load off the overlying crust. This tearing process has likely already occurred on the west side of the mountain range, where Iraq's Kurdistan region butts up against Turkey, new research finds. The tear is now heading toward northwest Iran. These dynamics aren't immediately obvious at the surface, but they reveal how the mantle and crust work together to shape Earth's topography, the researchers said in the new study, published Nov. 25, 2024 in the journal Solid Earth. The ocean plate was once the seafloor of Neotethys — an ocean that formed when the supercontinent Pangaea broke up into a northern continent, Laurasia, and a southern continent, Gondwana about 195 million years ago. Though Neotethys closed up more than 20 million years ago, the oceanic crust that used to underpin it is still affecting the Zagros mountain region, the new study found. "This plate is pulling the region downward from below," study author Renas Koshnaw, a researcher in geology at Göttingen University in Germany, said in a statement. As Neotethys closed up, the oceanic crust went under the Eurasian continent. The continental portion of the Arabian plate, which underpins modern-day Iraq and Saudi Arabia, was dragged behind, resulting in a collision with Eurasia. This collision created mountains, which pressed down on the crust around them, creating a depression. These mountains eroded into this depression over millions of years, their sediments forming the Mesopotamian plain where the Tigris and Euphrates rivers flow. RELATED STORIES –A history of Earth's supercontinents –Zealandia, Earth's hidden continent, was torn from supercontinent Gondwana in flood of fire 100 million years ago –Is Africa splitting in two? Koshnaw and his colleagues saw that on the southeastern side of this plane, there is an unusually thick layer of sediments, 1.9 to 2.5 miles (3 to 4 kilometers) deep. They mapped the area and used computer modeling to find that the weight of the mountains alone could not account for such a deep divot. Instead, they found that this region is being dragged down by the remains of the Neotethys oceanic plate, which is still plunging into the mantle. But the plate is also being torn apart as it descends. "Towards Turkey, the sediment-filled depression becomes much shallower, suggesting that the slab has broken off in this area, relieving the downward pull force," Koshnaw said. Understanding these dynamics can help inform the search for natural resources such as iron, phosphate and copper, which form in sedimentary rocks, the researchers said. Faults formed in the collision between the Arabian and Eurasian plates also give off large, deadly earthquakes.
