SOME REE-BEARING ACCESSORY MINERALS IN 2 TYPES OF VARISCAN GRANITOIDS, HUNGARY

The two main types of Hungarian Variscan granitoids are different in m any respects. The older one, occurring in South Hungary (Mecsek Mts.), is syncollision S-, I-type, migmatitic with a monzonitic suite. The r ocks are enriched in REE with abundant REE-bearing accessory minerals such as allanite, zircon, apatite, thorite, monazite, titanite and sec ondary rare earth fluorcarbonates. The REE distribution pattern of the whole rock is strongly influenced by the composition of allanite whic h is the most common REE-rich mineral. Later hydrothermal alteration c aused depletion of Ce, Th etc., from allanite and resulted in crystall ization of secondary rare earth fluorcarbonates and thorite. The diffe rent REE contents of zircon and apatite crystal cores suggest variable source rocks. The younger postcollision Variscan granitoids (along th e Velence-Balaton tectonic line) are intrusive S- or A-type with a gra nodioritic suite. The granitoids as well as their allanites are relati vely enriched in HREE+Y, due to flux of a volatile enriched solution a t the end of crystallization but the Sigma REE content is low.