OXYGEN-ISOTOPE GEOCHEMISTRY OF THE RHODOPE POLYMETAMORPHIC TERRAIN INNORTHERN GREECE - EVIDENCE FOR PRESERVATION OF PRE-METAMORPHIC ISOTOPIC COMPOSITIONS

The oxygen isotope geochemistry of the Rhodope polymetamorphic terrain of northern Greece is studied with the aim of examining the relative controls of fluid infiltration acid pre-metamorphic compositional vari ations on the isotopic compositions of rocks after metamorphism. Fluid infiltration during eclogite to amphibolite transformations did not r esult in any significant modification of isotopic compositions, as dem onstrated by the preservation of outcrop-scale compositional heterogen eity in metabasic rocks and modeling of marble - amphibolite isotopic profiles which shows that cross-layer advective fluid and diffusional exchange transport was minimal. The oxygen isotope compositions of the metamorphic rocks are largely inherited from their igneous and sedime ntary parent-rocks, thus indicating that the isotopic signatures of th e protoliths of the Rhodope metamorphic rocks were not modified during metamorphism. The results are consistent with recent studies demonstr ating that fluids are recycled within a rock series during metamorphis m.