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
Petermann Orogeny a set of vertically arcuate thrust faults which dip toward each other and accommodate vertical movement by essentially "squeezing" the central block up and out. Several northeast trending discontinuities including the Mundrabilla lineament divide the Petermann orogeny, with extensive vertical offsets across them, usually west-side-up, though the timing of this event is unknown. Six deformations are known (to be completed) Foliations associated with the Petermann Orogeny are typically steeply to gently south-dipping and subparallel to the thrust faults upon which they were developed. S regionally pervasive stretching lineation is potentially associated with some of these faults, especially in the deeper