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
Eburnean orogeny (LRC). Around 2090 Ma, a syntectonic trondhjemitic pluton intruded into the Archaean reelects of the Chegga series. Around 2070 Ma an asthenospheric upwelling released a large volume of post-orogenic magmas. Eburnian trends within the Eglab shield were repeatedly reactivated from the Neoproterozoic to the Mesozoic. Eburnean orogeny The Eburnean orogeny, or Eburnean cycle was a series of tectonic, metamorphic and plutonic events in what is now West Africa during the Paleoproterozoic era about 2200–2000 million years ago. During this period the Birimian domain in West Africa was established and structured. Eburnian faults are found in the Eglab shield to the