Article ID Journal Published Year Pages File Type
4734349 Journal of Structural Geology 2008 7 Pages PDF
Abstract
Dip isogons, drawn on the profile section of a fold by linking the points of equal dip on the inner and outer arcs, can be arranged in a rosette by displacing the isogons without changing their orientation until the mid-point of each isogon becomes the common point of intersection of all isogons. The end points of isogons in the rosette trace a characteristic curve that defines the fold geometry. This curve is a circle in parallel folds, an ellipse in flattened parallel folds, and it reduces to a pair of points in “similar” folds. Since isogons deform as material lines during flattening, the characteristic curve, namely, the ellipse, directly represents the strain ellipse in flattened parallel folds. The method is tested successfully on several examples of natural flattened parallel folds. The “isogon rosette” method allows representation of a given fold by a point on the Rs-θ plot, where Rs and θ are the two-dimensional strain ratio and the angle between the maximum principal strain and the fold axial trace, respectively.
Related Topics
Physical Sciences and Engineering Earth and Planetary Sciences Geology
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