Reply to discussion by G.I. Alsop and R.E. Holdsworth of 'Sheath fold development with viscosity contrast: analogue experiments in bulk simple shear' by Marques et al., Journal of Structural Geology, 30,1348-1353

摘要

Alsop and Holdsworth have done meritable work regarding the geometry of sheath folds. We value their discussion of our work, but we do not agree with their general conclusion that sheath fold geometry can be used to discriminate bulk strain type. We feel that deformation geometry is not unequivocally related to type of flow, and that it is therefore incorrect to make a priori assumptions about flow types in shear zones when investigating deformation geometries. Therefore, the conclusion of Alsop and Holdsworth that our experimental results support their findings is incorrect. What Marques et al., (2008) showed is that viscosity contrast, under bulk simple shear, can change the geometric features typical of passive simple shear, and therefore that geometry is not unequivocally related to type of flow.