Orogenic collapse

[1] There are two primary mechanisms at work in an orogenic collapse: excess gravitational potential energy and heat flow into the thickened crust.

The added heat softens the rock and makes it flow more easily, which can allow material in deeper sections to move up into thinner areas via buoyancy forces, reducing the total thickness.

[5] The Scandinavian Caledonides is an example of an orogeny and mountain chain that reached heights of 8–9 km and then collapsed in the Devonian, forming major extensional structures such as the Nordfjord-Sogn Detachment.

[7][8] The Basin and Range Province of the Western United States was previously a high plateau within the American Cordillera, which has since been extended and thinned.

The cause of the extension is debated, though it is likely related to the transition from a subduction zone to a transform boundary between the North American and Pacific plates, as well as possible mantle upwelling.

[12][13] Although the Tibetan Plateau is in a primarily compressional environment caused by the collision of the Indian and Eurasian plates, it is also experiencing east-west extension which began c. 14 Ma.