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

Volcanic rocks from Antisana volcano (Ecuador) show a clear enrichment in Sr, Nb, Ti and P relative to normal calc-alkaline rocks. Furthermore, some of 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 appropriate beneath the volcano, we propose that these rocks are derived from the partial melting of an hydrated mantle, previously and heterogeneously metasomatised by adakitic magmas at shallower depth. ((C) Academie des sciences / Elsevier, Paris.).