Structural Geometry of the Dharwar Rocks near Chitradurga

Abstract The major structure south of Chitradurga is a southerly closing, very steeply plunging, nearly vertical fold (Chitradurga Fold) defined by the BIF horizons. This is a second generation structure and the dominant schistosity with NNW-SSE strike is parallel to the axial plane of this fold. The first generation structures are represented by minor folds only. They have variably oriented axes and their axial planes are bent by the major Chitradurga Fold. The strike of the third generation axial planes varies from NNE-SSW to ESE-WNW, and the axes are generally steeply plunging. During the second deformation, folds formed at different stages and their geometry was modified by rotation in the subsequent stages of progressive deformation. The axes of the minor folds show a wider range in orientation than the direction of maximum elongation in the rocks, and there is often an angle between the two. The distribution of the bedding plane poles in the projection diagrams of most of the sectors indicate steeply plunging ß (F2). The major Chitradurga Fold shows a conical geometry with a subvertical cone axis and very small apical angle.