Adakitic and calc-alkaline lavas of Antisana volcano (Ecuador): petrogenetic hypothesis

Volcanic rocks from Antisana volcano (Ecuador) show a clear enrichment in S r, Nb, Ti and P relative to normal calc-alkaline rocks. Furthermore, some o f them show low heavy rare earth and Y concentrations, a feature of typical adakites. However, as the P-T conditions for adakite genesis are not appro priate beneath the volcano, we propose that these rocks are derived from th e partial melting of an hydrated mantle, previously and heterogeneously met asomatised by adakitic magmas at shallower depth. ((C) Academie des science s / Elsevier, Paris.).