There are several ways of quantifying shear strains across shear zones. The principal aim is to use these data to establish the displacement across the shear zone. We can use deflected markers that were originally oriented at 90 degrees to the shear plane - this is the easiest case to follow. Alternatively we can use the general case of any pre-existing marker - as long as we can establish its original orientation. Finally we can determine the shear strain from new foliations. In all case these estimations should be done on a plane (e.g. an outcrop surface) perpendicular to the shear plane and parallel to the shear direction. It is important then to be able to evaluate the orientation of the shear plane. You can follow the method by clicking here.
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