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Convergence and Shortening |
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Following subduction of the oceanic lithosphere and the collision of continental margins, ongoing convergence of landmasses at the surface of the Earth leads to surface shortening of intra-continental domains. As strain occurs without large scale volume losses, surface shortening must be accommodated by thickening.
The style of deformation varies greatly from homogeneous pure shear where strain is homogeneously distributed throughout the entire lithosphere, to highly heterogeneous strain where contrasted strain and strain regimes develop in different lithospheric layers at various locations.
The sketches on the right illustrate a number of possibilities each characterized by pure shear strain in the lithospheric mantle. The thin black lines emphasize the orientation of finite flattening plane, thick lines represent faults and shear zones. |
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