An international team of geologists from the Woods Hole Oceanographic Institute (WHOI) has discovered anomalous geochemical compositions under Panama: there is an unexpected tunnel of 1,609 kilometers under the earth’s surface that would connect the Galapagos Islands with Panama and through which magma can flow, as they found magmatic samples formed more than 1,500 kilometers away, material that was blown away thanks to a “mantle wind” that blows under the earth’s crust.
The scientists used helium isotopes and other fluid and rock geochemical data to show that the volcanic material comes from the Galapagos plume.
“The lateral transport of material from the plume represents a little-studied mechanism that disperses enriched geochemical signatures in mantle domains away from the plumes,” explains David Bekaert, a postdoctoral fellow at WHOI and lead author of the study published in the journal Proceedings of the National. Academy of Sciences. “We can compare volcanic systems with the body of a living organism; when the organism bleeds, it is like magma that comes out of the Earth. And you can measure the composition of that magma, just like you can measure a blood type. In this In the study, we measure an unexpected composition of volcanic gas, kind of like when a human has a rare blood type. In the case of Earth, we then try to explain where it came from in terms of deep geological processes. “
The hottest material that comes from the deepest layer of the Earth rises above the Galapagos plume, responsible for volcanism and the formation of the Galapagos archipelago. Once it begins to travel in the shallow mantle, some material also moves laterally, extending into Central America.
This passage, located about 100 km below the Earth’s surface, can allow a flow of mantle materials to travel from under the Galapagos Islands to under Panama, something that represents a form of transport never before discovered on our planet. and which could help explain why Panama has very few active volcanoes.
The chemical observations were combined with geophysical images of the deep interior of the Earth to identify the source and direction of this “mantle wind.”
The geology of this area is very curious. Both Panama and the Galapagos are on microplates surrounded by larger tectonic plates. These larger plates have a subduction zone where they meet continental regions, and the plates sink deeper into the mantle. Usually this region sinks deep enough to block lateral movement of the material. But the Panama plate acts as a “slab window” so the material can flow past the subduction area.
This discovery of the lateral transport of exotic and deep material through Earth’s interior could have far-reaching implications for scientists’ understanding of the chemical evolution of our planet over geological time. The discovered mantle flow is poorly studied, but there are other unexplained anomalies in the mantle chemistry around the world . The researchers hope to conduct a similar analysis in Chile and, at some point, expand this method around the world because it is something that no one had thought of before.
Referencia: David V. Bekaert, Esteban Gazel, Stephen Turner, Mark D. Behn, J. Marten de Moor, Sabin Zahirovic, Vlad C. Manea, Kaj Hoernle, Tobias P. Fischer, Alexander Hammerstrom, Alan M. Seltzer, Justin T. Kulongoski, Bina S. Patel, Matthew O. Schrenk, Sæmundur A. Halldórsson, Mayuko Nakagawa, Carlos J. Ramírez, John A. Krantz, Mustafa Yücel, Christopher J. Ballentine, Donato Giovannelli, Karen G. Lloyd, Peter H. Barry. High 3He/4He in central Panama reveals a distal connection to the Galápagos plume. Proceedings of the National Academy of Sciences, 2021; 118 (47): e2110997118 DOI: 10.1073/pnas.2110997118