Using differential geometry to describe 3-D folds

We provide methods to objectively characterize 3-D folds and present applications for different fold types at varying scales and formed in different tectonic settings. Algorithms based on differential geometry quantify all geometric aspects of the surfaces. The geologic curvature classification defines the shape and orientation of points on the folded surface. The curvature threshold introduces a method to extract geologically significant aspects of fold shape by disregarding curvature magnitudes less than a certain value. This permits the evaluation of the cylindricity of the folded surface at particular points. (C) 2007 Published by Elsevier Ltd.