Abstract provided by author:
In comparison with primordial mantle composition these alkali intrusive rocks are generally enriched in highly incompatible elements such as Nb and P, with low values for K and Ba
Geochemical features observed show that the basanites are distinct from the other rock types. Their primitive character is reflected by high contents of Nb, Zr, Ba, Sr, and Y, and relatively low contents of Rb, Th and Pb. The tephrite-phonotephrite-tephriphonolite-phonolites represent products of a number of lineages related by similar parent compositions. Fractional crystallisation results in increasing SiO2, K2O, Al2O3 and Na2O, Rb, Th and Pb, but decreasing total iron, MgO, CaO, Ti02, Co, Cu, V, Ba and Sr