There’s a secret geological passage under Panama: what it could reveal

It could explain why the rocks of the Earth's mantle are more than 1,500 km from where they originated. The opening is located about 100 km below Earth's surface.

Under Panama is a secret geological passage that could explain why the rocks of Earth's mantle are more than 1,609 km from where they originated. The opening is located about 100 km below the Earth's surface and would allow, a flow of mantle materials to travel from the Galápagos Islands to under Panama. This particular form of transport, never discovered before, could also help answer why the country on the isthmus connecting Central and South America has very few active volcanoes. The study was published in the journal Proceedings of the National Academy of Sciences.

The Geological Secret Passage Study

On the west coast of Central America, the Cocos tectonic plate is pushing oceanic crust under the continental crust of the North American, Caribbean and Panamanian tectonic plates in a process called subduction. This subduction zone creates a line of volcanoes called the Central American Volcanic Arc. But the volcanism stops in western Panama, explained David Bekaert, a postdoctoral scholar in marine chemistry and geochemistry at the Woods Hole Oceanographic Institution in Massachusetts.

To understand how subduction in the Central American area works, the researchers delved into the geochemistry of the region, collecting volcanic rock samples and gas and fluid samples from hot springs. The team particularly focused on helium and lead isotopes. Normally, the mantle is mostly silicate rocks, which are rocks with a particular structure of silicon and oxygen atoms. However, scholars discovered that there were some strange anomalies beneath Central America. In western Panama and behind the volcanic arc in Costa Rica, Bekaert said they detected geochemical compositions similar to those found in the Galápagos Islands, far away from the area.

What the secret geologic passage would reveal

Scientists then turned to seismic imaging of the mantle, which uses seismic waves to map what's below the surface, and computer modeling to try to explain what might be going on, and found that the solution would be deep within Panama. When a tectonic plate slides under another tectonic plate during subduction, that subducting plate doesn't disappear; it retains its structure, only gradually heating and deforming. "Just below Panama, there is a hole that allows these mantle components to flow in," Bekaert said. The "window" may be the result of a natural, pre-existing fracture in the subducting Cocos crust, or it may be a place where the crust broke apart during subduction. In any case, it lets the materials pass, from one side to the other of the plate and connects in this way the Galapagos to Panama.

Regarding the inactivity of volcanoes in the Central American country, the explanation could be traced precisely in the existence of the crack in the crust that would be rich in water and would make it difficult to let the magma pass. Another research has instead identified a "hidden world" in the inner core of the Earth, while recently it has been hypothesized that our planet could have developed around an alien rock nucleus.

Stefania Bernardini