U-Pb Isotopic Ages of Uraninites from Kulu, Himachal Pradesh and Berinag, Uttar Pradesh

U-Pb Isotopic ages of a eight uranmites, occurring as veins and disseminations in quartzite in Kulu district of Himachal Pradesh and Berinag (Pithoragarh district) of Uttar Pradesh are reported. The ages are discordant and show the general pattern (²⁰⁷Pb/²⁰⁶Pb) age > (²⁰⁷Pb/²³⁵U) age > (²⁰⁶Pb/²³⁸U) age. An attempt has been made to find a convergent age related perhaps to the actual time of mineralizanon and to explain the discordancy in terms of episodic loss of lead/gain of uranium, Uraninites occurring as disseminations in quartzite in Kulu are estimated to have been formed at 1232±120 my., whereas those occuring as veins and fracture fillings appear to be younger Both the mineralizations show the effect of a recent episodic event (55 my.).