GEOCHEMISTRY AND PETROGENESIS OF HANUMAN-TIBBA GRANITE OF KULLU VALLEY, HIMACHAL-HIMALAYA

A maiden attempt has been made to study the far-flung Hanuman Tibba Gr anites of Kullu valley, Himachal Pradesh. The granite has intruded the low grade Haimanta (similar to Lahaul) Formation which tectonically o verlies the Rohtang Gneissic Complex. Integrated field, petrographic a nd geochemical studies have revealed that it is peraluminous S- type g ranite derived from sedimentary protolith. Compositional difference in terms of depletion of Fe, Mg, Ti, Ca, Sr, Zr and enhancement of Si, K and Rb from margin to core of the granite body is consistent with fra ctional crystallization process. The emplacement of Hanuman Tibba Gran ite on the same tectonic level as Jispa and Ratilaman granite (500+/-m a) in adjacent Lahaul-Spiti region suggests a Cambro-Ordovician age fo r the Hanuman Tibba Granite.