Relation between trace and major element composition of the Chitaldrug metabasalts,Mysore, India,and the Archaean mantle

The ferromagnesium trace-element content of the Chitaldrug metabasalts is not compatable with its normative composition. The major elements resemble quartz-normative tholeiites and some trace-elements like Co are even higher or similar to that of olivine-normative tholeiites or the deep-oceanic tholeiites. The relationship between MgO and ferromagnesium traces is sympathetic but of very low order. The high ferromagnesium trace content in this suite and its poor relation with major elements suggest that probably the Archaean/Early Precambrian upper mantle had higher levels of these elements than the present mantle. Lateral compositional inhomogeneities in the Archaean upper mantle are also indicated from the available trace-element data over the Archaean metabasalts from different shields.