Geologists find Americas collision occurred earlier than previously thought

Geoscientists have discovered that the major tectonic collision between Central America and South America occurred significantly earlier than previously understood. According to a study published in Earth and Planetary Physics, the most intense crustal compression and collision-related deformation in the Northern Andes likely took place during the Oligocene and middle Miocene periods.

Led by Victor Piedrahita and J. Li, the international research team analyzed volcanic rocks from the Combia Volcanic Province in central Colombia, dating from approximately 12 to 6 million years ago. By employing magnetic fabric analysis—a technique that examines the orientation of magnetic minerals to distinguish between original volcanic activity and later tectonic deformation—researchers found that many of these rocks retained their primary magnetic characteristics.

The lack of significant deformation in these late Miocene rocks suggests that the strongest collisional events had largely concluded before this period. This finding provides new insights into the geological development of the Americas and may lead to improved models of how the Andes were formed.