The elastic-plastic-viscous lithosphere
Ductile flow: Lower crustal flow in the Shuswap Metamorphic Core Complex (Canadian Cordillera). Rey et al. in prep.
Metamorphic Core Complexes are domical features involving a metamorphic core including migmatites (product of partial melting) wrapped by a shear zone marking the boundary with the brittle upper crust. Despite prominent extensional features at the surface of the crust, seismic surveys reveal a flat Moho. The centripetal ductile flow of the lower crust toward the metamorphic core explains the flat Moho despite strong surface extension in the upper crust.