An anomalous geochemical composition beneath Panama has been discovered by an international team of scientists – and they believed it did not form there. It formed over 1,500 kilometers (900 miles) away near the Galápagos islands, carried over thanks to a “Mantle Wind” that blows under the Earth’s crust.
The research, published in Proceedings of the National Academy of Sciences, suggests an interesting model. Hotter material coming from the Earth's deeper layer rises on the Galápagos plume, responsible for the volcanism and formation of the Galápagos archipelago. Once it begins to travel in the shallow mantle, some material also moves laterally, spreading all the way to Central America.
“The lateral transport of plume material represents an understudied mechanism that scatters enriched geochemical signatures in mantle domains far from plumes,” Dr David Bekaert, from the Woods Hole Oceanographic Institution, said in a statement.
“We can compare volcanic systems to the body of a living organism; when the organism bleeds, it’s kind of like magma bleeding out of the Earth. And you can measure the composition of that magma, just like you can measure a blood type," he explained.
"In this study, we measured an unexpected volcanic gas composition, sort of like when a human has a rare blood type. In the case of the Earth, we then try to explain where it came from in terms of deep geological processes.”
The geology of the area is truly fascinating. Both Panama and the Galápagos are on microplates surrounded by larger tectonic plates – for example, the Cocos plate that skirts a large swathe of Central America, and the Nazca plate which is against South America. These larger plates have a subduction zone where they meet the continental regions, with the plates sinking down deeper into the mantle.
The region is called a slab, and usually, it sinks deep enough that blocks the lateral motion of material. However, the Panama plate is unusual, acting as a "slab window" so the material can flow past the subduction area. The geochemical composition of the inner layers of our planet is very diverse, so the team can track where the material appears to have originated from, even if it’s far away from the source.
“Exotic volcanic chemical features have previously been documented in Central America. We use these chemical characteristics as indicators for large geological processes. In this case, our findings help explain why plume-derived volcanic material shows up in central Panama, even though there are no active volcanoes there,” explained Bekaert.