Indenter tectonics, also known as escape tectonics, is a branch of

strike-slip tectonics Strike-slip tectonics or wrench tectonics is the type of tectonics that is dominated by lateral (horizontal) movements within the Earth's crust (and lithosphere). Where a zone of strike-slip tectonics forms the boundary between two tectonic plates, ...

that involves the collision and

deformation Deformation can refer to: * Deformation (engineering), changes in an object's shape or form due to the application of a force or forces. ** Deformation (physics), such changes considered and analyzed as displacements of continuum bodies. * Defor ...

of two continental plates. It can be observed in many situations around the world, and is associated with high-grade metamorphism and extensive lateral displacement of

strata In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as ei ...

along oblique strike-slip faults

Model

The concept of indenter tectonics was first introduced by Molnar and Tapponnier in 1975, with reference to the Himalayan

orogeny Orogeny is a mountain building process. An orogeny is an event that takes place at a convergent plate margin when plate motion compresses the margin. An ''orogenic belt'' or ''orogen'' develops as the compressed plate crumples and is uplifted t ...

. Various experiments have illustrated the process by which deformation occurs. 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'). In a tectonic setting, the terms ‘rigid’ and ‘soft’ refer to the strength of the

lithosphere A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust (geology), crust and the portion of the upper mantle (geology), mantle that behaves elastically on time sca ...

. 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. 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. It is possible to have a combination of the two models.

Examples

Real-world examples differ by the rigidity of the indenter, the size and

rheology Rheology (; ) is the study of the flow of matter, primarily in a fluid ( liquid or gas) state, but also as "soft solids" or solids under conditions in which they respond with plastic flow rather than deforming elastically in response to an appl ...

of both the host and the indenter, and the extent of lateral confinement. The best known active example is the system of strike-slip structures observed in the

Eurasian plate The Eurasian Plate is a tectonic plate that includes most of the continent of Eurasia (a landmass consisting of the traditional continents of Europe and Asia), with the notable exceptions of the Indian subcontinent, the Arabian subcontinent and ...

as it responds to collision with the

Indian plate The Indian Plate (or India Plate) is a minor tectonic plate straddling the equator in the Eastern Hemisphere. Originally a part of the ancient continent of Gondwana, the Indian Plate broke away from the other fragments of Gondwana , began mov ...

, but similar events can be found all over the Earth.

Asia

* Indian and Eurasian plates (Himalayan orogeny) * Palawan microcontinental block and

Philippine Mobile Belt In the geology of the Philippines, the Philippine Mobile Belt is a complex portion of the tectonic boundary between the Eurasian Plate and the Philippine Sea Plate, comprising most of the country of the Philippines. It includes two subduction z ...

North America

Slave craton The Slave Craton is an Archaean craton in the north-western Canadian Shield, in Northwest Territories and Nunavut. The Slave Craton includes the 4.03 Ga-old Acasta Gneiss which is one of the oldest dated rocks on Earth. Covering about , ...

and Churchill province * Ouachita Terrane

Europe

African African or Africans may refer to: * Anything from or pertaining to the continent of Africa: ** People who are native to Africa, descendants of natives of Africa, or individuals who trace their ancestry to indigenous inhabitants of Africa *** Ethn ...

and Eurasian plates ( Alpine orogeny)

Model

Examples

Asia

North America

Europe

References

Further reading