Metabasalts from the sheeted dyke complex and pillow lavas in the Karmøy ophiolite, southwest Norwegian Caledonides, show large ranges of both trace element concentrations and incompatible element ratios. These features are best explained by batch melting and to some extent by dynamic melting of a depleted, heterogeneous mantle, with some subsequent modification of the melts by fractional crystallization. The geochemistry may reflect a more complicated tectonic environment of basalt generation than for other, geochemically more uniform ophiolitic sequences further to the north in the Norwegian Caledonides. Geological features of the Karmøy ophiolite and another nearby ophiolitic sequence (the Lykling ophiolite) indicate the presence of an oceanic fracture system. It is speculated if a relationship may exist between the varied geochemistry and the oceanic fracture system.