Proterozoic Newer Dolerite Dyke Swarm Magmatism in the Singhbhum Craton, Eastern India

Precambrian mafic magmatism and its role in the evolution of Earth’s crust has been paid serious attention by researchers for the last four decades. The emplacement of mafic dyke swarms acts as an important time marker in geological terrains. Number of shield terrains throughout the world has been intruded by the Precambrian dyke swarms, hence the presence of these dykes are useful to understand the Proterozoic tectonics, magmatism, crustal growth and continental reconstruction. Likewise, the Protocontinents of Indian Shield e.g. Aravalli-Bundelkhand, Dharwar, Bastar, and Singhbhum Protocontinent had experienced the dyke swarm intrusions having different characteristics and orientations. In Singhbhum craton, an impressive set of mafic dyke swarm, called as Newer dolerite dyke swarm, had intruded the Precambrian Singhbhum granitoid complex through a wide geological period from 2800 to 1100 Ma. Present chapter focuses on the published results or conclusions of these dykes in terms of their mantle source characteristics, metasomatism of the mantle source, degree of crustal contamination and partial melting processes. Geochemical characteristics of these dykes particularly Ti/Y, Zr/Y, Th/Nb, Ba/Nb, La/Nb, (La/Sm)PM are similar to either MORB or subduction zone basalts that occur along the plate margin. The enriched LREE-LILE and depletion of HFSE especially Nb, P and Ti probably indicate generation of these dykes in a subduction zone setting.