|Sources of oceanic basalts: Radiogenic isotopic evidence|
White, W.M. (1985). Sources of oceanic basalts: Radiogenic isotopic evidence. Geology (Boulder Colo.) 13(2): 115-118
In: Geology. Geological Society of America: Boulder. ISSN 0091-7613, more
Basalts; Earth mantle; Lithology; Mid-ocean ridges; Marine
Oceanic basalts can be subdivided into five distinct groupings on the basis of thier Sr, Nd, and Pb isotope composition. These classes, represented by mid-ocean ridge basalts (MORB) and St. Helena, Kerguelen, the Society Islands, and the Hawaiian Islands, may represent different but internally heterogeneous mantle reservoirs or merely distinct groups within which chemical evolution has proceeded in a similar manner. Little systematic geographic distribution of volcanism tapping these sources is apparent. Depletion has been most important in the evolution of the MORB-type reservoirs, whereas crustal recycling has dominated the evolution of sources of the Kerguelen and Society types. Primitive mantle is identifiable in the Sr, Nd, Hf, and Pb isotope characteristics of the Hawaiian source only. The evolution of St. Helena-type sources remains enigmatic.