http://www.sciencedirect.com/science/article/pii/S1674987113001345

Many elongated,lenticular plutons of porphyritic granitoids are distributed mainly near the southern and northern margin of the Chhotanagpur Gneissic Complex(CGC) which belongs to the EW to ENEeWSW tending 1500 km long Proterozoic orogenic belt amalgamating the North and South Indian cratonic blocks.The late Grenvillian(1071 64 Ma) Raghunathpur porphyritic granitoid gneiss(PGG)batholith comprising alkali feldspar granite,granite,granodiorite,tonalite,quartz syenite and quartz monzonite intruded into the granitoid gneisses of southeastern part of CGC in the Purulia district,West Bengal and is aligned with ENEeWSW trending North Purulia shear zone.Mineral chemistry,geochemistry,physical condition of crystallization and petrogenetic model of Raghunathpur PGG have been discussed for the first time.The petrographic and geochemical features(including major and traceelements,mineral chemistry and87Sr/86 Sr ratio) suggest these granitoids to be classified as the shoshonitic type.Raghunathpur batholith was emplaced at around 800 C and at 6 kbar pressure tectonic discrimination diagrams reveal a post-collision tectonic setting while structural studies reveal its emplacement in the extensional fissure of North Purulia shear zone.The Raghunathpur granitoid is compared with some similar granitoids of Europe and China to draw its petrogenetic model.Hybridization of mantle-generated enriched mafic magma and crustal magma at lower crust and later fractional crystallization is proposed for the petrogenesis of this PGG.Mafic magma generated in a post-collisional extension possibly because of delamination of subducting slab.Raghunathpur batholith had emplaced in the CGC during the final amalgamation(w1.0 Ga) of the North and South Indian cratonic blocks.Granitoid magma,after its generation at depth,was transported to its present level along megadyke channel,ways within shear zones.