Oxygen isotope geochemistry of the Rhodope polymetamorphic terrain in northern 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 and pre-metamorphic compositional variations on the isotopic compositions of rocks after metamorphism. Fluid infiltration during eclogite to amphibolite transformations did not result in any significant modification of isotopic compositions, as demonstrated by the preservation of outcrop-scale compositional heterogeneity 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 sedimentary parent-rocks, thus indicating that the isotopic signatures of the protoliths of the Rhodope metamorphic rocks were not modified during metamorphism. The results are consistent with recent studies demonstrating that fluids are recycled within a rock series during metamorphism.