Tectonics and stratigraphy of the Gurgunta schist belt of the Dharwar Craton, south India
Journal of the Geological Society of India 66(3): 303-317
ISSN/ISBN: 0016-7622 Accession: 020202594
The early Archaean oval-shaped, high-grade Gurgunta schist belt in the northern part of the eastern Dharwar craton of south India constitutes a part of the intensely deformed migmatized basement of the low-grade volcano-sedimentary sequence of the Dharwar craton. The Gurgunta schist belt consists of two blocks of a migmatised volcano-sedimentary sequence separated by an E-W trending shear zone. Contrary to the earlier interpretations, the regional structure of the belt is not a dome. The earliest episode of deformation (D (sub 1) ) has produced pervasive planar fabric in metavolcanics and in granitoid rocks after migmatisation of volcano-sedimentary rocks in its early history. D (sub 2) has produced major and minor isoclinal folds along with axial planar pervasive gneissic banding while the D (sub 3) has produced major and minor tight to isoclinal folds on foliation. The map pattern is controlled by D (sub 3) deformation. D (sub 4) and D (sub 5) are of mild intensity and less prominent on a regional scale in comparison to earlier deformations. The grade of metamorphism, migmatisation, the structural history and the presence of E-W trending shear zone suggest that the belt is probably older than the low-grade supracrustal belts in the adjoining areas.