Geological secret passages beneath Panama may explain why rocks from the Earth’s mantle were found more than 1,000 miles (1,609 kilometers) from where they originated.
About 62 miles (100 km) below the surface of the Earth, this opening may allow the flow of mantle material to travel all the way from under the Galapagos Islands to under Panama.
This undiscovered mode of transportation may also help explain why Panama has so few active modes of transportation. Volcano..Cocos, West Coast of Central America Structural plate It sneaks under the continental crust of the tectonic plates of North America, the Caribbean, and Panama, a process called subduction, and pushes the oceanic crust.this Subduction zone Creates a row of volcanoes called the Central America Volcanic Arc, where lava penetrates boundaries. However, volcanic activity ceases in western Panama on the Panama Plate, said David Bekar, a postdoctoral fellow in marine chemistry and geochemistry at the Woods Hole Oceanographic Institution in Massachusetts.
This relative peace has long been a mystery.Bekaert and his colleagues are now reporting in a new study published in the journal on November 23. Minutes of the National Academy of Sciences The culprit could be a window-like opening in a Coco’s tectonic plate that is being pushed down toward the center of the globe.
Bekaert and his colleagues are trying to better understand how subduction works near Central America.Cocos plate subduction in North America can be a major cause earthquake, Contains 2017 Chiapas EarthquakeA magnitude 8.1 earthquake that killed dozens of people.
To find out more, researchers delved into the geochemistry of the region, collecting volcanic rock samples and gas and fluid samples from hot springs.They were interested in finding out the ratio of molecular isotopes, which are variations of the same thing. atom The number of neutrons in the nucleus is different.In this case, the researchers are especially helium When Lead..
“Various sources of geological material usually have different compositions, so we can track contributions from different regions of the mantle,” Bekaert told Live Science.
The mantle is mainly composed of silicate rocks. Silicate rocks are rocks with a specific structure. Silicon When air atom. However, the exact configuration can vary significantly even over short distances. Researchers have discovered that there are some strange anomalies beneath Central America.
“We have found that there are some exotic features behind certain parts of Central America, the volcanic arcs of western Panama and Costa Rica. [of geochemistry] It’s really similar to what you have in the Galapagos Islands, “Bekaert said.
(Mantle) Blown by the wind
This was strange, Bekaert said, because there was no clear way to explain how the Galapagos Islands mantle element would reach Panama. Next, researchers turned to seismic imaging of the mantle, which uses seismic waves to map what is beneath the surface of the earth, and computer modeling to explain what is happening.
They found that just below Panama, the buried part of the Cocos Plate might hold the answer. When a structural plate slides under another structural plate during subduction, the subducting plate does not just disappear. It retains its structure even when mashed by the mantle and is gradually heated and warped.
“Just below Panama, there is a hole through the slab, a hole that allows the inflow of this mantle component,” Bekaert said.
This window may be the result of the natural existing destruction of the subducting Coco’s crust. Or it could be where the crust snapped during the subduction. In any case, it allows the material to pass from one side of the plate to the other, like a breeze from an open window.
It left the question of what is driving the breeze. Researchers have discovered two possibilities. The first is that the material is moving through the Panama rupture zone, which is the crust and upper mantle rupture zone connecting the Galapagos Islands and Panama. But it’s hard to know what drives long-haul transport through the zone, Bekart said. It is not clear if even such transportation is possible.
A more likely scenario is that the typical large circulation of the mantle simply drives the material through the opening of the subducting slab.
“When you model the mantle cycle at this location, you expect this deep global mantle flow,” Bekart said.
The presence of the mantle window can also explain the lack of active volcanoes in Panama, Bekaert said. Water trapped in the crust of the subducting slab tends to promote the formation of volcanoes as it lowers the melting point of rocks and forms magma. The opening of the slab under Panama means that there is a gap in the water-rich crust at that location. This means that it is more difficult for melted magma to flow there.
Bekaert said the mantle flow discovered by the team has not been fully studied, but there are unexplained anomalies in the chemistry of mantles around the world. The team hopes to do a similar analysis next in Chile, but eventually wants to extend this method around the world.
“No one has ever thought about this process, so I just want to consider all the data,” Bekart said.
Originally published in Live Science
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