Densities of High Grade Metamorphic Rocks from South Indian Granulite Terrain

2.67 gm/cc is the normally assumed density value for the upper crystalline crust, in gravity data reductions. The densities measured in 210 metamorphic rocks, spread over a traverse distance of 2500 km from the granulite terrain of South India, gave a mean density of 2.77 gm/cc. The results show that 2.67 gm/cc is too Iow a value and 2.76 ± 0.01 gm/cc would be an appropriate choice for the mean density of the upper crystalline crust in South Indian granulite terrain.

Though in some of the charnockites the magnetic susceptibility is considerably reduced due to retrograde metamorphism, the effect is not perceptible on the density. The areas with high paleopressures have the maximum mean densities.