Publisher © Czech Geological Survey, ISSN: 2336-5757 (online), 0514-8057 (print)
The role of granites in the genesis of the Rožná U-deposit
Abstract
The source of U in the uranium deposit at Rožná is traced in the neighbouring Moldanubian biotite-bearing paragneisses. The remobilization and concentration of U is probably connected with melting processes of the parental gneisses. The granites that were found in the Rožná mine are garnet bearing, and very felsic. The granites are located in two different positions. (1) Some have an intrusive character. The second type (2) forms several-meter-thick-conformable layers in the paragneisses. The granites are strongly depleted in Al, Fe, Mg, Ca, HFS and light REE, but enriched in Si, K, Rb, U if compared with parental gneisse. Garnet rich granites are enriched 7 to 10 times more in HREE and Y in comparison with garnet free types. this unusual geochemical feature originated as a consequence of low degree melting of the metasedimentary protolith followed by magmatic garnet accumulation.
