It can be observed in many situations around the world, and is associated with high-grade metamorphism and extensive lateral displacement of strata along oblique strike-slip faults[1] The concept of indenter tectonics was first introduced by Molnar and Tapponnier in 1975,[1] with reference to the Himalayan orogeny.
[2] A continent-continent collision can be visualized as a 'die-and-metal' model, with a rigid die (the 'indenter') moving into a softer, rigid-plastic metal (the 'host').
The strong lithosphere of the indenter remains relatively undeformed and its boundaries are preserved, while the host allows deformation by lateral movement of crust both along the contact with the indenter and within the host.
[4] The indenter block is too buoyant to subduct, so crustal accommodation is achieved by either shallow underthrusting and crustal thickening, or formation and later lateral displacement of several microplates.
[2] The best known active example is the system of strike-slip structures observed in the Eurasian Plate as it responds to collision with the Indian Plate, but similar events can be found all over the Earth.