Sevier orogeny Sevier thrust faults. The Sevier orogeny was preceded by several other mountain-building events including the Nevadan orogeny, the Sonoman orogeny, and the Antler orogeny, and partially overlapped in time and space with the Laramide orogeny. Since the Sevier and Laramide orogenies occurred at similar times and places, they are sometimes confused. In general the Sevier orogeny defines a more western compressional event that took advantage of weak bedding planes in overlying Paleozoic and Mesozoic sedimentary rock. As the crust was shortened, pressure was transferred eastward along the weak sedimentary layers, producing “thin-skinned” thrust faults that generally get younger to the
Andean orogeny were inverted in the Miocene. After a period of quiescence the Agrio fold and thrust belt resumed limited activity in the Eocene and then again in the Late Miocene. In the south of Mendoza Province the Guañacos fold and thrust belt (36.5° S) appeared and grew in the Pliocene and Pleistocene consuming the western fringes of the Neuquén Basin. The early development of the Andean orogeny in southernmost South America affected also the Antarctic Peninsula. In southern Patagonia at the onset of the Andean orogeny in the Jurassic, extensional tectonics created the Rocas Verdes Basin, a back-arc basin whose southeastern