The magma-mixed granitoid system, Eastern Dharwar Craton, India: evidences from the mafic enclaves and syn-plutonic dykes from Madugulapalli

To understand the fundamental processes for the generation of granites, associated rock types and compositional diversity, we studied the Madugulapalli granitoids that constitute a part of the Eastern Dharwar Craton (EDC) of southern India.The Madugulapalli area consists of three rock types, including a host granitic rock (GN, syeno-monzogranite), mafic microgranular enclaves (MME) and syn-plutonic dykes (SPD).The MME and SPD are characterised by (a) spherical and ellipsoidal shapes with associated chilled margins, (b) the presence of megacrysts of K-feldspar and plagioclase and (c) the presence of acicular apatite, ocellar quartz and plagioclase with oscillatory zoning and resorption surfaces, all suggesting that they are globules of mafic magma derived from the mantle sources and SPD are injected into the crystal mush of the felsic host.Geochemical analyses suggest that MME and SPD are derived from the mixing of a partial melt from heterogeneous mantle and crustal source.The MME and SPD exhibit colinear compositions with the host GN, suggesting that they are the products generated by magma mixing in different proportions of injected mafic melts and the host granite.During various stages of crystallisation, granitic magma interacted with a smaller amount of mafic magma.Based on mixing calculations, a mass fraction of felsic magma (xA = 0.71) mingled with mafic magma to generate hybrid rocks in the Madugulapalli region.Field, petrographic and geochemical evidence suggests that they are generated in a subduction environment in which large-scale mantle and crustal-derived magmas are produced and mixed at the crustal emplacement level.Hence, the Madugulapalli rocks represent a magma-mixed granitoid system from the EDC.