Studies of oceanic plateaus and continental flood basalts are an ongoing focus of the SOEST Isotope Lab. One of our studies is on the Ontong Java Plateau, which is one of the largest oceanic plateaus (roughly the size of Alaska). It is much larger than continental flood basalt provinces such as the Columbia River or Deccan Traps, but probably has a similar process of origin. Plateaus and flood basalts may be formed by the birth of new mantle plumes (or "plume heads").
The figure below shows Nd and Pb isotopic data for lavas from the Solomon Islands, where the edge of the Ontong Java Plateau is uplifting the plateau's crust above sea level due to a collison with an island arc in the region. Data for the plateau (pink fields and red and yellow squares) show remarkable homogeneity among lavas samples over distances of more than 1500 km, suggesting that the plume head may have been compositionally uniform despite its huge size.
For more information on our work in this area, see:
J.J. Mahoney, M. Storey, R.A. Duncan, K.J. Spencer and M. Pringle, (1993) Geochemistry and Age of the Ontong Java Plateau in: The Mesozoic Pacific: Geology, Tectonics and Volcanism Geophysical Monograph 77 American Geophysical Union, p 233-261.
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last page update on 29 April 1995