An investigation of lower crustal deformation: Evidence for channel flow and its implications for tectonics and structural studies

The sense of shear may be constant across an HGNA shear zone, giving it the geometry and kinematics of a crustal-scale (kilometres thick) detachment zone. Alternatively it may reverse across the body, consistent with channel flow. Structural evidence therefore supports current ideas on the behaviour of the middle to lower crust during orogeny, and illustrates the deformation mechanisms involved. We describe the association with special reference to the Monashee complex, and discuss the implications of our interpretation for the kinematics of high-strain zones, palinspastic reconstruction, and interpretation of deformation fabrics at various scales.