An international research team has pushed back the age of one of Earth's most significant tectonic boundaries by millions of years. The Aleutian Arc, a chain of islands and underwater volcanoes stretching between Alaska and Kamchatka, marks where the Pacific Plate slides beneath the North American Plate. New analysis published in Nature Communications shows this subduction zone began at least 56 million years ago — much older than earlier models suggested.
The revised timeline provides a clearer window into a major reorganization of global plate movements. Understanding when and how this boundary formed helps geologists reconstruct ancient ocean basins and continental drift patterns. The findings also carry implications for climate science, as shifting tectonic plates have long influenced atmospheric carbon levels.
Previous estimates placed the subduction zone's start around 50 million years ago or younger. The new date comes from geochemical and radiometric analysis of rocks collected along the arc. Researchers say the evidence points to a continuous subduction process that began in the early Eocene epoch.
The Aleutian Trench remains one of the most seismically active regions on the planet, generating frequent earthquakes and volcanic eruptions. A more precise understanding of its deep history could improve models of seismic hazard and tsunami risk for coastal communities in Alaska and the Russian Far East.
The study adds fresh evidence to the debate over how quickly tectonic boundaries can form and evolve. Some geologists caution that the findings may rely on localized rock samples that don't reflect the entire arc's history.