Naslov
Petrographic, geochemical and geochronological investigation on granitic pebbles from Permotriassic metasediments of the Tisia terrain (eastern Papuk, Croatia)

Autori
Biševac, Vanja ; Krenn, Erwin ; Balen, Dražen ; Finger, Fritz ; Balogh, Kadosa

Izvornik
Mineralogy and petrology (0930-0708) 102 (2011), 1; 163-180

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Tisia; Slavonian Mountains; granitic pebbles; Th-U-Pb monazite dating; K-Ar muscovite dating
(Tisia; Slavonian Mountains; granitic pebbles; Th-U-Pb monazite dating; K-Ar muscovite)

Sažetak
Granitic pebbles occurring in the Permotriassic metasedimentary sequence of eastern Papuk, Slavonian Mountains, Croatia, were recognized to represent a coherent group of felsic, muscovite-albite metagranites. Fabrics, modal compositions and geochemical data imply that the rocks are derivatives of S-type granites formed through a combination of igneous and subsequent metasomatic processes. A Variscan formation age is demonstrated by K-Ar dating on coarse muscovite (range of 329-317 Ma) as well as by electron microprobe based Th-U-Pb monazite dating (338 ± 15 Ma). Additionally to the Variscan metasomatic processes of albitization and greisenisation, which led to an almost complete replacement of K-feldspar and biotite by albite and coarse muscovite, pebbles were affected by a younger phase of alteration resulting in the formation of a fine-grained sericitic matrix. The fine sericite yields K-Ar ages of 91-83 Ma. A substantial reheating of the rocks during the Cretaceous is also indicated by the growth of new monazite dated at 106 ± 10 Ma. Yttrium-contents of the Cretaceous monazite from the granite pebbles (0.3-0.9 wt. % Y2O3) are compatible with metamorphic temperatures of ~350-400 °C. These data confirm recent concepts according to which large parts of the Slavonian Mountains received a pervasive Cretaceous low-T regional metamorphic overprint. Furthermore, the pebbles provide useful information on the nature of the eroded Variscan crust of the Tisia Terrain, which has obviously contained considerable amounts of evolved high-level S-type granites modified through albitization and greisenization.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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