This study will continue analysis of fold development in single layers by use of computer modelling and by the study of natural folds. The aim is to better understand folding processes in non-linear materials, in layers oriented oblique to the principal bulk strain directions, and in layers that undergo non- coaxial strain. Finite element models will be used to study variations in shape and strain distribution in symmetrical folds as functions of viscosity contrast, power-law exponent, initial shape, and initial wavelength of the layers. A comparison will be made between the development of symmetrical folds & that of asymmetrical folds that develop either in simple shear or in oblique layers subjected to pure shear. Criteria will be developed, based on fold shape and strain, that will give information on bulk deformation paths in rocks. Natural folds will be studied for arc length vs. thickness distribution, fold shape, and strain pattern. These data from natural folds will be compared with the experimental data in order to gain insight on their rheology during deformation. The results of this study will greatly improve our understanding of rock behavior during tectonic folding.
