Geometric analysis of superposed folds in the Kimbi area (Cameroon Pan-African fold belt) based on the Fold Profiler method

Abstract

Fold shape analyses using the program Fold Profiler method are presented for folds with interference in the Kimbi area with the aim of deciphering their geometry. Two types of functions, conic sections and cubic Bézier curves, were fitted to the natural fold profiles to analyse the fold shape. Two dominant families have been distinguished: parabolic folds for F 1 folds and parabolic to elliptical folds for F 2 and F 3 folds. We also use Ramsay’s scheme ( t ′ a versus α plot) for classifying the geometry of the folded layers. In this classification, F 1 and F 3 folds belong to class 1C and class 3 folds while F 2 are of classes 1B, 1C and 3. Class 1B folds are formed by buckling while class 1C folds are formed by flattening of parallel folds. The variation of fold shape can be explained by the variation in the rheological properties of the folded layers as a result of changes in physical conditions, or by changes in the kinematics of the folding processes. These data, which are the first ever folding results in this region, can be integrated into the tectonic evolution models Northwestern Cameroon’s Pan-African fold belt.