THE USE OF U TH RATIOS AND REE PATTERN IN SAVANNA TREES AS A GUIDE TOURANIUM MINERALIZATION IN THE BENUE TROUGH, NIGERIA/

Bark samples of Boswilia dalzielli and Afromosia laxiflora, two savann ah trees from the Zone uranium prospect and from the background areas were analysed for 24 elements using NAA (neutron activation analytical ) techniques. The analytical data from the two types of trees are comp ared. Although both types of trees show low absorption of uranium, the bark of Bosweilia dalzielli shows high U/Th ratios upto 17 times the background values, which clearly define the outline of the ore uranium zone. Trees growing within the mineralised zone show enhanced values of Ba, U, Cs, Na, K and Mg and to a lesser degree a depletion of the o ther elements when compared to corresponding background values. A decr ease in the content of most REE with increasing U/Th ratios is establi shed in the bark samples of Bosweilia dalzielli. The above trends are not very pronounced in samples from Afromosia laxiflora. The U/Th rati os and the REE (Rare Earth Elements) pattern in Bosweilia dalzielli co uld be used as a guide for detecting concealed mineralisation in the B enue Trough.