Some Observations on the Structure, Metamorphism, and Geological Evolution of Peninsular India

Peninsular India, like other shield areas of the world, displays an ingrained pattern of successive orogenic belts. The description of these belts is accompanied by a tectonic map in which are noted the main structural trends as well as many of the reliable ages so far determined.

The variations in the grades of metamorphism which can be recognised in South India are delineated in a sketch map. There is a general progressive increase in the intensity of metamorphism from north-west to south-east. The highest grades are met within the southern and south-eastern parts of the Peninsula where charnockites and khondalites are prevalent.

The successive stages in the geological evolution of Peninsular India are next described. The structural pattern as well as relative ages indicate that the oldest rocks are found in the type area for Dharwar Schists in Mysore State. This region is a continental nucleus, and the Eastern Ghats and Satpura provinces are later Precambrian accretions which have been folded by pressures directed towards this Archaean nucleus.