Mafic Granulite Xenoliths in Neogene Alkali Basalts from the Western Pannonian Basin: Insights into the Lower Crust of a Collapsed Orogen

Abstract

Mafic granulite xenoliths from Pliocene alkali basalts of western melt. This can be explained by mixing between mafic back-arcHungary represent the lower crust of the Pannonian Basin. The basin-like tholeiitic melts and pre-existing lower crust that has high xenolith suite from two localities, Szigliget and Bondorohegy, includes Sr, Pb and O isotopes but low Nd/Nd. The most crustally medium-pressure mafic granulites (plagioclase+pyroxene±garnet) contaminated rocks have Nd/Nd ratios that can only be that range from gabbroic (i.e. orthopyroxene-free) to two-pyroxene explained by assimilation of an old component (>1 Ga). Thus, and garnet-bearing lithologies. Two groups can be distinguished on although the crustal block accreted to Europe in the Mesozoic was the basis of chemistry: light rare earth element (LREE)-depleted predominantly oceanic in character, it must have contained slivers granulites that have Sr, Nd and O isotope ratios typical of depleted of Precambrian crust. mantle, and LREE-enriched granulites that have higher Sr/ Sr (0·706–0·709), lower Nd/Nd (0·5128–0·5123) and higher dO (+7·5 to +10·4‰). The LREE-depleted group also has lower Pb/Pb and Pb/Pb for a given Pb/