Evidence for the Occurrence of Carbonatites on the Cape Verde and Canary Islands

Abstract

THE distinction between hydrothermal carbonate-rich rocks and carbonatites is frequently difficult and the occurrence of carbonatites on the Cape Verde and Canary Islands1,2 has therefore been a controversial matter. Moreover, the geological setting of these deposits, an oceanic environment and the absence of a ring structure, is anomalous for carbonatite rocks. We have developed criteria by which we may distinguish carbonatites from hydrothermal limestones, from studies of several European and African carbonatite complexes (refs. 3 and 4, and M. J., F. P. and C. J. A., to be published). In this communication we shall use these criteria to identify some carbonate-rich rocks in the Cape Verde and Canary Islands as carbonatites.