Alkaline Granitoids from the Northern Shear Zone of Puruliya District, West Bengal

The roughly E-W trending North Puruliya Shear Zone is characterised by generally E-W striking deformed and brecciated porphyritic granitoid gneisses, in places, along with brecciated and limonitised quartzite, aegirine-riebeckite granite gneiss and few small occurrences of apatite-magnetite rock, REE and U-Th-rich barite-bearing small pegmatites, and small bodies of alkali feldspar salite granitelsyenite and poorly exposed carbonatite at one place. The occurrence, field relation, petrography and geochemistry of the carbonatite, apatite-magnetite rock, pegmatites enriched in REE, U-Th, and barite etc. and the alkaline granitoids along the North Puruliya Shear Zone, all taken together suggest possible genetic link of the alkaline granitoids with a carbonated silicate magma emplaced at depth along the rift zone.