Fold pattern analysis around Kanjamalai Salem district Tamilnadu

Thirukumaran ,R Suresh

doi:10.34256/ijceae2025

Abstract

Kanjamalai one of the fascinating location in Southern Granulite Terrain (SGT) for studying Archaean geology and structures as the entire hill is made up of variety of rock types like two pyroxene granulite, amphibolites, quartzo - feldsapthic gneisses, banded iron formation, and intrusive rocks like dunite, peridotite and pegmatite and beautifully carved structures. The entire hill resembles a canoe shape with doubly plunging fold structure with E-W elongation. The entire hillock seems to sit pretty on mylonitised hornblende biotite gneisses which also have a common N70-95 degree trend and sub vertical dip with NE plunge which is in contradiction to centrally plunging lineations of the hill. The SW part of Kanjamalai near Chinasrirangapadi was displaying beautiful fold structures, with interference pattern out of which six domains were selected for detailed study and analysis. The multiple generation folded structure will have a clue in reconstructing the deformation history of this Kanjamalai. The observed f1, f2 and f3 folds show significant Type III interference pattern as that of Ramsay and 01 and 03 type folds of Bernhard Grasemann. Wavelength –amplitude analysis was made to generalize and regroup the observed folds in to high amplitude, high wavelength or open folds, low wavelength and Mesoscopic folds. And visual harmonic analysis was made to analyse the symmetry of the folds and analyze the geometry, symmetry and harmony and genesis of the fold in terms of relative timing of the events.

Highlights

Fold pattern analysis will give a comprehensive picture on the geometry and harmony of the folds and in turn that reflects in the kinematics involved can be predicted
The varying amplitude and wavelength were measured using the photograph of the domain
Six domains were selected and analysis was made on wavelength and amplitude and the analysis suggested different types of fold like and the analysis of the six domains

Summary

Introduction

Fold pattern analysis will give a comprehensive picture on the geometry and harmony of the folds and in turn that reflects in the kinematics involved can be predicted. The high wavelength folds are called as open fold and they were O1 type of Bernhard Grasemann, et al,(op.cit.) where the previous folds was superimposed by another with horizontal axial plane possible represent a horizontal thrust (Figure 4) [1]. An visual analysis was made on six domains to analyze the geometry, symmetry and harmony and genesis of the fold in terms of relative timing of the events.

Results

Conclusion