Latest news with #subduction
Yahoo
15-06-2025
- Science
- Yahoo
Tectonic plates can spread subduction like a contagion — jumping from one oceanic plate to another
When you buy through links on our articles, Future and its syndication partners may earn a commission. Subduction zones, where one tectonic plate dives underneath another, drive the world's most devastating earthquakes and tsunamis. How do these danger zones come to be? A study in Geology presents evidence that subduction can spread like a contagion, jumping from one oceanic plate to another — a hypothesis previously difficult to prove. This result "is not just speculation," says University of Lisbon geologist João Duarte, who was not involved in the research. "This study builds an argument based on the geological record." Because subduction drags crust deep into the earth, its beginnings are hard to examine. The new study provides a rare ancient example of potential subduction "infection." Its authors say they've discovered evidence that neighboring collisions triggered East Asia's "Ring of Fire," a colossal subduction system currently fueling earthquakes and volcanoes from Alaska to the southern Indian Ocean. Nearly 300 million years ago China was a scattering of islands separated by the ancient Tethys and Asian oceans. Established subduction zones consumed these oceans, welding the landmasses into a new continent and raising mountains from Turkey to China. By 260 million years ago this subduction seems to have spread and begun pulling down the neighboring Pacific plate. "The dying act of those closing oceans may have been to infect the Pacific plate and start it subducting westward under the Asian continent," says study lead author Mark Allen, a geologist at Durham University in England. "In one form or another, it's been diving down ever since." The smoking gun in this case is the "Dupal anomaly," identified by a geochemical fingerprint from the ancient Tethys Ocean and what is now the Indian Ocean. When the study authors unexpectedly found this signature in volcanic rocks from the western Pacific, they surmised that material from the Tethys had spread eastward across a plate boundary from one subduction zone to another — triggering the neighboring plate's descent. "It's like seeing someone's fingerprint at a crime scene," Allen says. RELATED STORIES —Africa is being torn apart by a 'superplume' of hot rock from deep within Earth, study suggests —Gigantic 'mud waves' buried deep beneath the ocean floor reveal dramatic formation of Atlantic when Africa and South America finally split —Yosemite's ultra-deep canyon may have been carved in part by a ghost volcano and river, provocative research suggests But the mechanism of spread remains mysterious. The researchers suspect that transform faults — boundaries where plates slide past one another, like the San Andreas Fault — may act as weak spots where slight changes in collision angle or speed can destabilize dense oceanic crust, causing it to sink. Duarte compares the scenario to aluminum foil in water. "The foil floats," he says, "but the slightest tap will cause it to sink." If subduction spreads this way, could the Atlantic Ocean's relatively quiet plate margins be next? The massive 1755 Lisbon earthquake hints at early subduction invasion there. Duarte suggests parts of Iberia and the Caribbean are undergoing this process's initial stages: "In another 100 million years a new Atlantic 'Ring of Fire' may form — just as it once did in the Pacific." This article was first published at Scientific American. © All rights reserved. Follow on TikTok and Instagram, X and Facebook.
Forbes
31-05-2025
- General
- Forbes
Rocks Date Onset Of Modern Plate Tectonics To 2 Billion Years
When plate tectonics first emerged on Earth is still debated. Some models suggest that Earth at first possessed a single protoplate covering the entire planet. This protoplate eventually broke open, the fragments forming tectonic plates. Other models suggest plate tectonics may have evolved gradually over billions of years. A new study, Xiaoli Li and colleagues from the Earth and Space Sciences Department, Peking University, published evidence from the petrologic record suggesting that the modern style plate tectonics begun in the Paleoproterozoic — over 1.6 billion years ago. The team analyzed eclogites from the Belomorian Province in Baltica. Eclogite is a metamorphic rock containing red almandine-pyrope garnet hosted in a matrix of green omphacite (a sodium-rich pyroxene). Eclogites typically results from high to ultrahigh pressure metamorphism of basaltic lava at low thermal gradients as it is subducted to the lower crust to upper mantle depths in a subduction zone. Subduction zones, where one tectonic plate slides beneath another plate, are a key element of modern plate tectonics. Radiometric dating of the rocks revealed an age around 2 and 1.8 billion years ago, making them the oldest known subduction eclogites. The protolith, the original lava rock, is even older with an age ranging between 2.7 and 2.5 billion years. The eclogite from Baltica shows some chemical similarities to 'modern' eclogite, formed just 65 million years ago, from the Himalayas. The Himalaya orogen formed when the former ocean between Asia and India was subducted, and remains of oceanic crust and continental fragments were uplifted by the collision. The authors suggest that in a similar way the eclogite from Baltica demonstrates the existence of a mountain range, comparable to the Himalaya range, on the supercontinent Columbia over two billion years ago. Plate tectonics has, so far, only been observed on Earth, and may be essential to making a world hospitable for life by constantly remixing and renewing the outer layers of the planet. The new results, together with previous research, suggests that something happened around 3.8 to 2 billion years ago, with Earth switching from a single plate towards plate tectonics and changing its geological evolution forever. The study,"Orosirian cold eclogite from Baltica marks the onset of modern plate tectonics," was published in the journal Earth and Planetary Science Letters.
