A new study suggests that the most intense phase of the collision between Central and South America occurred millions of years earlier than previously estimated. Researchers examined volcanic rocks (aged between 12 and 6 million years) from the Combia region in the Northern Andes of central Colombia. By analyzing the orientation of magnetic minerals within these rocks, they could determine whether the rock’s structure had remained unchanged since formation or had been altered later by tectonic forces. The findings indicate that by the late Miocene, the major crustal shifts had already largely concluded, meaning the peak of the collision likely happened before about 10 million years ago. This challenges long-standing models of how the Andes formed and could lead to improved geological models of plate interactions in the region.
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