摘要
Kinematic vorticity (Wk) is defined to quantify the relative contributions of pure shear component and simple shear component in ductile deformation zone, and is a very important constraint on the evolution of a ductile shear zone. Ductile shear zone of the Daqingshan detachment fault which superimposed on the Mesozoic thrusts is exposed on both southern and northern limbs of Hohhot metamorphic core complex, with a top to south-east detachment direction. The result shows that the fault experienced a progressive increase of simple shear component until complete simple shear in the earlier stage (higher temperature), 0.94~1.00. Mean vorticy (Wm) increased along the direct of detachment, from 0.22~0.31 to 0.95~1.00,due to the thickening and thinning deformation transition. The northern part is at the centre of thrust and have a higher pure shear component. The simple shear component decreased while pure shear component increased in the later stage (lower temperature), from 0.73~0.81. Pure shear component increases from ductile penetrative brittle-ductile-ductile stain partitioning during exhumation.