Superposed Folding in the Aravalli Rocks of the Type Area around Udaipur, Rajasthan

Around Udaipur, the Precambrian rocks belonging to the Aravalli System are represented by feldspathic greywacke grading to phyllite and mica schist, calc-arenite, and ferruginous and carbonaceous quartzites. The rocks display a high degree of structural complexity resulting from the impress of three distinct periods of folding (F₁, F₂ and F₃). The earliest folding movement (F₁) produced tight to isoclinal folds with drawn-out hinges. The F₁ folds are accompanied by a set of very well developed axial plane schistosity. These folds are presumed to have been initially recumbent with E-W to NW-SE axial trend. The second fold movement (F₂) refolded the F₁ folds to upright, open to occasionally isoclinal folds. The F₂ folds have variable plunge and an overall northerly axial trend. The third fold movement has resulted in the formation of tight to isoclinal folds (F₃) of small and intermediate scales on the limbs of larger F₂ folds. The F₃ folds are characterized by a set of axial plane crenulation cleavages. The superposition of the three fold systems has resulted in complex interference patterns on different scales.