Abstract
Intermediate Series lava from Mauritius composes a suite of primitive alkali basalt, basanite, and nephelinite, which display marked primary geochemical enrichment trends for K, Ti, P, Sr, Rb, Ba, and Zr and have probably been erupted unmodified from at least 45 to 60 km (15 to 20 kb). Younger Series lava, primarily alkali basalt with subordinate basanite, displays less well developed primary geochemical enrichment patterns that show scattering compatible with the overprinting effects of low-pressure olivine fractionation.
Incompatible-element enrichment patterns in these series, together with highly variable Rb/Sr, K/Rb, K/Sr, and K/Ba ratios, suggest that small (<10 percent), possibly sequential degrees of partial melting of a single peridotitic mantle were involved in their formation. Low incompatible-element abundances in the Younger Series probably reflect relatively higher degrees of melting, but they may indicate reprocessing of mantle material already depleted in these elements by the earlier Intermediate Series melting event.
