Ordovician-Silurian true polar wander as a mechanism for severe glaciation and mass extinction

The Ordovician-Silurian transition experienced severe, but enigmatic, glaciation, as well as a paradoxical combination of mass extinction and species origination. Here we report a large and fast true polar wander (TPW) event that occurred 450-440 million years ago based on palaeomagnetic data from South China and compiled reliable palaeopoles from all major continents. Collectively, a similar to 50 wholesale rotation with maximum continental speeds of similar to 55 cm yr(-1) is demonstrated. Multiple isolated continents moving rapidly, synchronously, and unidirectionally is less consistent with and plausible for relative plate motions than TPW. Palaeogeographic reconstructions constrained by TPW controlling for palaeolongitude explain the timing and migration of glacial centers across Gondwana, as well as the protracted end-Ordovician mass extinction. The global quadrature pattern of latitude change during TPW further explains why the extinction was accompanied by elevated levels of origination as some continents migrated into or remained in the amenable tropics.

Automated summary

This study reports a large and fast true polar wander event that occurred 450-440 million years ago and provides evidence based on paleomagnetic data and paleopoles from major continents. The study also suggests that this event can explain the migration of glacial centers and the mass extinction at the end of the Ordovician period.