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

Abstract

Abstract 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.