Alleghanian orogeny Alleghanian orogeny The Alleghanian orogeny or Appalachian orogeny is one of the geological mountain-forming events that formed the Appalachian Mountains and Allegheny Mountains. The term and spelling Alleghany orogeny was originally proposed by H.P. Woodward in 1957. The Alleghanian orogeny occurred approximately 325 million to 260 million years ago over at least five deformation events in the Carboniferous to Permian period. The orogeny was caused by Africa colliding with North America. At the time, these continents did not exist in their current forms: North America was part of the Euramerica super-continent, while Africa was part of Gondwana. This collision formed
Andean orogeny Pampeanas) where the effects of the ancient Pampean orogeny can be observed, owes it modern uplift and relief to the Andean orogeny in the Tertiary. Similarly the San Rafael Block east of the Andes and south of Sierras Pampeanas was raised in the Miocene during the Andean orogeny. In broad terms the most active phase of orogeny in area of southern Mendoza Province and northern Neuquén Province (34–38° S) happened in the Late Miocene while arc volcanism occurred east of the Andes. At more southern latitudes (36–39° S) various Jurassic and Cretaceous marine transgressions from the Pacific are recorded in