Dredged basaltic rocks from the seaward extensions of the Reykjanes and Snaefellsnes volcanic zones, Iceland

Data for basaltic rocks dredged on the Reykjanes Ridge and Jokulbanki off the southwest coast of Iceland are presented. The rocks from the Reykjanes Ridge, which are identified as recent lavas, are olivine tholeiites and quartz tholeiites very similar to those formerly described from this region. The heterogeneous Jokulbanki dredges were identified as erratics. In the light of the present and other recent data on tholeiitic rocks from Iceland and the Reykjanes Ridge, a distinct chemical gradient, together with increased scatter across Iceland is demonstrated for certain incompatible elements. This is in accordance with the mantle plume theory.