Acadian orogeny Acadian orogeny The Acadian orogeny is a long-lasting mountain building event which began in the Middle Devonian, reaching a climax in the early Late Devonian. It was active for approximately 50 million years, beginning roughly around 375 million years ago, with deformational, plutonic, and metamorphic events extending into the Early Mississippian. The Acadian orogeny is the third of the four orogenies that created the Appalachian orogen and subsequent basin. The preceding orogenies consisted of the Potomac and Taconic orogeny, which followed a rift/drift stage in the Late Neoproterozoic. The Acadian orogeny involved the collision of a series of Avalonian continental
Pampean orogeny Belt of the Brasiliano Orogeny, but in difference to the Paraguay Belt that ended up in the interior of Gondwana the Pampean Orogen remained at a continental margin. The orogen eventually ceased activity and was succeeded by the Famatinian orogeny further west. The eastern magmatic belt of the Pampean orogeny is interpreted as the remains of a volcanic arc associated with an east-dipping subduction zone while the western one is thought to represent a younger volcanic arc that developed on what was once the accretionary prism of the orogen. There have been differing views among geologists on the tectonic and