Chemical composition and alter ation of Cr-spinels from Meliata and Penninic serpentinized peridot ites (Western Carpathians and Eastern Alps)

Cr-spinel is a relatively wide spread accessory mineral in the Mesozoic ophiolites of the Western Carpathians (mainly in the Meliata Unit) and in the Penninic Unit (Rechnitz tectonic window group). Cr-spinel chemical composition in both these occurrences (Meliaticum, Penninicum) shows the lherzolitic character of the original ultrabasites. It was found impossible to distinguish the source rocks (peridotites) of these two oceanic domains on the basis of the chemical composition of the Cr-spinels. Many Cr-spinels from both tectonic units are af fected by various levels of alter ation (in general, decrease of Al2O3, Cr2O3, MgO, enrichment in FeO, Fe2O3, SiO2, locally also in MnO and ZnO).