1 De part ment of Min er al ogy and Pe trol ogy, Fac ulty of Nat u ral Sci ences, Comenius Uni ver sity, Mlynská dol ina G, 842 15 Bratislava, Slovakia 2 De part ment of Ge ol ogy and Pa le on tol ogy, Fac ulty of Nat u ral Sci ences, Comenius Uni ver sity, Mlynská dol ina G, 842 15 Bratislava, Slovakia 3 State Geo log i cal In sti tute of Dionýz Štúr, Mlynská dol ina 1, 817 04 Bratislava, Slovakia Uher P., Plašienka D., Ondrejka M., Hraško L. and Koneèný P. (2013) Ura nium-rich monazite-(Ce)

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... om the Krivá type granitic boul ders in con glom er ates of the Pieniny Klippen Belt, West ern Carpathians, Slovakia: com po si tion, age de ter mi na tion and pos si ble source ar eas. Geo log i cal Quar terly, 57 (2): 343-352, doi: 10.7306/gq.1089 Monazite-(Ce) is a wide spread ac ces sory min eral in gra nitic cob bles of the Krivá type (Zástranie and Krivá lo cal i ties) in polymict con glom er ates of Cre ta ceous flysch se quences, the Pieniny Klippen Belt, West ern Carpathians, NW Slovakia. The gran ites show leucocratic mus co vite-bi o tite granodiorite com po si tion and peraluminous calc-al ka line, S-type char ac ter. The monazite con tains un usu ally high U, com monly 1 to 3, and in some places up to 6.6 wt.% UO 2 , to gether with 5 to 7.7 wt.% ThO 2 . A cheralite-type sub sti tu tion [Ca(U,Th)REE -2 ] is the dom i nant mech a nism of U 4+ + Th 4+ in cor po ra tion into the monazite struc ture in the Zástranie sam ple, whereas both cheralite-and huttonite-type sub sti tu tion [(Th,U)SiREE -1 P -1 ] are ev i dent in the Krivá gra nitic cob ble. Ura nium alone pre fers the CaU 4+ (REE) -2 mech a nism, whereas Th fa vours the huttonite sub sti tu tion. The chem i cal U-Th-Pb dat ing of monazite from both gra nitic cob bles show an Early Car bon if er ous age (346 ± 2 Ma), which is con sis tent with the main meso-Variscan, orogen-re lated plutonic ac tiv ity in the Cen tral Carpathian area (Tatric and Veporic superunits). Anal o gous U-rich monazites were de tected in some Variscan S-type leucogranites of the Rimavica mas sif (South Veporic Unit) and the Bojná and Bratislava mas sifs (north ern part of the Tatric Unit). On the ba sis of struc tural and palaeogeographic data, the North Tatric Zone is the most plau si ble source of the monazite-bear ing gra nitic boul ders in the Pieniny Klippen Belt. How ever, the source gra nitic body was most likely hid den by en su ing tec tonic short ening along the north ern Tatric edge af ter de po si tion of the Coniacian-Santonian Upohlav type con glom er ates.