The stable isotopic evolution of a metamorphic complex, Naxos, Greece

A detailed study of the stable isotope composition of pelites, amphibolites and marbles from the M2 metamorphic complex on Naxos is presented. The low grade rocks of this metamorphic complex have isotopic compositions typical of metasedimentary rocks whilst those at high grades have values typical of igneous rocks. The isotopic compositions of rocks at intermediate grades vary smoothly between these two end-members. This variation is shown to result from the superimposition of at least two fluid flow events on a pre-existing isotopic gradient. The contrast between the observed seemingly simple mixing trend and the complexity of the isotopic history of these rocks has important implications for quantitative studies of fluidrock interactions.