Mantle source of the Paleogene collision-related magmas of the Eastern Rhodopes (Bulgaria) and Western Thrace (Greece): Characteristics of the mafic magmatic rocks

摘要

FMM (Fertile MORB Mantle according to PEARCE & PARKINSON 1993) -normalized patterns of Tertiary gabbros, absarokites, basalts to andesitic basalts from Eastern Rhodopes and Western Thrace show a considerable enrichment in Nb and Zr, in lesser degree in Ti, Y, Yb. The patterns of many elements coincide with those of supra-subduction zone basalts (from island arcs and marginal basins). This is in favour of the hypothesis that the discussed collision-related magmas originated from metasomatically enriched mantle. Metasomatism took place during Upper Cretaceous subduction of the Tethyan oceanic crust under the Rhodopes. Some rocks in the southern part of the Eastern Rhodopes and in the Western Thrace show a negative Ti anomaly with respect to Zr and Y This is explained by residual amphibole in the mantle source.