Geochemical characterization of the granites and mafic enclaves of the hyderabad granitic region: implications for crustal growth and evolution

The ∼ 2.5 Ga granitoids and the mafic enclaves in them occurring around Nalgonda, Suryapet, Medak and Nagarkurnool have been studied for their field, petrographic and geochemical (major, trace and rare earth element) signatures. The granitoids are predominantly grantic- to granodioritic in composition and are characterized by slight LREE enrichment, no significant HREE depletion and a negative Eu amomaly. Yb vs Ta plot shows that the granitoids were emplaced in a volcanic arc environment. Nb-Ta depletion noted in the multielement spidergrams suggests deep crustal origin by the anatectic melting of the crust and fractional crystallization. The mafic enclaves with their gabbro-dioritic/noritic/tonalitic nature appear to be mostly restites. However, the mafic enclaves from the Nalgonda area point to their derivation by emplacement of pre-existing mafic crustal material into the granites.