Abstract

It was first suggested by R.W. Kay that adakites may represent melts of subducted slab: since then, the term adakite has become synonymous with slab melts based on their unusual geochemical signature. This contribution, using the Northern volcanic zone of the Andes as an example, aims (1) to expose the weakness in simply associating a geochemical signature with a genetic mechanism and (2) to underline the importance of using several integrated lines of evidence in assessing the viability of slab melting. We conclude that although slab melting probably occurs in some arcs, regional geochemical trends in the Northern volcanic zone and their relationship to the subduction-zone architecture are not indicative of slab melting and can be accounted for by normal arc magmatic processes acting on wedge-derived basaltic magmas.

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