An Appraisal of Multi-Layered Fold Classifications: Insights from the Analysis of the Complex Folds in the South Delhi Fold Belt, Beawar, Rajasthan, India

ABSTRACT Folds exhibited by layered rocks are the most common and well-studied geological structures formed under varied tectonic settings across the globe. The study of folds offers critical insights into regional tectonics and stress regimes. However, in spite of the conspicuous dominance of the multi-layered folds in nature, most fold-related studies focus on single-layer systems, limiting our understanding of multilayer fold complexities. Moreover, the classification model of multi-layered folds cannot be based on the parameters invoked for the single-layered folds, mainly due to the colossal variation in the intrinsic parameters between different adjacent layers of the multi-layered fold system. The present investigation deals with the F2 generation (multilayer) folds in the South Delhi Fold Belt, employing Fourier analysis and geometric parameters to classify and analyse these structures. By examining the fold geometry, internal anatomical variations, and the influence of flattening strain, this study offers a holistic understanding of multilayer fold formation and evolution. Our analysis highlights the limitations of the existing classification schemes when applied to multilayer folds, emphasising the need for modifications in existing methodologies. Systematic application of established methods coupled with the introduction of new parameters provides a robust framework for future research into the mechanism of development of these complex folds. Accordingly, the systematic development of these methods has been discussed and documented in detail to emphasise their various rationale and limitations. Thus, this work contributes significantly to the comprehension of multilayer fold development within the context of regional tectonics, in particular, and to the broader field of structural geology at large.