The role of mixing processes in andesite genesis - deep sediment recycling versus shallow crustal contamination

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Andesites are the typical volcanic rocks at active continental margins and the average continental crust has an andesitic composition. Many andesitic magmas form by complex mixing processes involving sedimentary material that is either subducted into the mantle wedge or may be assimilated in the crust by the ascending magma. The Aegean arc represents the subduction zone with one of the highest sediment recycling rates on Earth and the magmas show whole-rock geochemical evidence of a significant sediment contribution. In order to define the depths of the magma sources and the mixing processes we suggest to study the major and trace element as well as Sr-Nd-Hf-Pb-O isotope composition of minerals like olivine, amphibole, clinopyroxene, and plagioclase and potential glass inclusions in lavas from the Methana/Aegina volcanoes in the Aegean arc. The mineral phases allow insights into the mixing processes of different end-members at different depths that can be determined by thermo-barometry. The Methana/Aegina lavas are well-suited for such a case study because they are geochemically well-described and variable with extreme compositions of the mixing end-members and they contain abundant mineral phases.