Petrogenesis of the protolith for the Tirodi gneiss by A-type granite magmatism: The geochemical evidence

In the Central Indian region, the Tirodi gneisses occur intimately associated with the Sausar Group metasediments. The protoliths for these gneisses might have originated by rift-related intracontinental felsic A-type (anorogenic) magmatism. The geochemical signatures in them like high Zr+Nb+Y+Ce, Ga/Al, Zr/Ni, Rb/Sr and Y/Sc, are quite similar to the A-type granite characteristics and point to the derivation of the protoliths by the melting of lower crustal dehydrated assemblages at high temperatures attained as a result of possible pending of basaltic magma/magma underplating. The occurrence of mafic rocks related to subduction zone magmatism and back-are environment in the vicinity of these gneisses in the Central Indian region attest to such an origin far the protoliths of the Tirodi gneisses.