New magnetic study pushes back timing of Central-South America collision

A team of geoscientists studied magnetic fabrics in volcanic rocks dated to roughly 12-6 million years old from Colombia's Combia Volcanic Province. By distinguishing original volcanic magnetic signatures from later tectonic overprints, they found most rocks show little deformation, implying that major compressional forces had already weakened. Consequently, the most intense phase of the Central-South America collision likely occurred during the Oligocene to middle Miocene, not the late Miocene as earlier models suggested.

Lead authors Victor Piedrahita and JinHua Li argue this revision improves understanding of Andes formation and continental plate dynamics. The research was published in Earth and Planetary Physics and funded by the National Natural Science Foundation of China.