Figure F24. Trace element contents of basalts from Site 1136, normalized to primitive mantle values of Sun and McDonough (1989). This diagram illustrates the mobile behavior of Rb and K, which are highest in the altered basalt, and the relatively immobile behavior of the other elements. The presence of a continental component would produce a relative depletion (trough) at Nb. Instead, a small peak is seen in the four least-altered samples. The high contents of Nb, Zr, Ti, and Y in the vesicle-rich segregation are caused by magmatic evolution, as explained in the text.