The Behaviour of Trace Elements in the Magmatic Members of the Singhbhum Granitic Complex

Seventeen trace elements in 37 total rock samples belonging to six magmatic units of Singhbhum Granite, and nearly as many trace elements in II individual minerals separated from these rocks were estimated by quantitative and semi-quantitative spectrographic analysis respectively. Uranium was determined fluorimetrically in all the 37 samples. The trace element distributions in these samples have been studied in relation to those of the major elements as computed from the modal analyses on the basis of optical and chemical data on the constituent minerals.

The trends of variation of the trace elements and of the diadochic element ratios in these rocks conform broadly to those expected under conditions of fractional crystallisation of volatile-rich granitic melts. Distinctive trends of variation of several trace elements and diadochic element ratios with increasing differentiation were found for the three distinct but closely related phases into which these intrusive units may be classified on structural and petrologic grounds. Multivariate analyses and t-tests on 12 trace elements in samples belonging to the three phases indicate that the three phases of granites have significantly different trace element compositions.