Redistribution of U, Pb and REE in association with alteration of uranium minerals from the Koongarra deposit, Northern Territory, Australia

Abstract

Summary In order to investigate migration behavior of REE in uranium matrix by alteration, and to understand a chronological history of the alteration processes, in-situ isotopic analysis of U, Pb and REE by using a Sensitive High Resolution Ion MicroProbe (SHRIMP) was applied to the Koongarra uranium deposit sample (Northern Territory, Australia) which contains uraninite and two kinds of secondary uranium minerals (curite and sklodowskite). Highly discordant U-Pb data from all of the uranium minerals suggest that the secondary uranium minerals were formed by sequential alteration of primary uraninite 50-580 Ma ago, and subsequently affected by recent weathering. The difference of REE abundance patterns between primary uraninite and secondary uranium minerals show geochemical evidence of REE redistribution during the secondary mineralization by the interaction of primary ore body with meteoric water.