Naslov
A distinct tectono-metamorphic evolution at the southern edge of Tisia Mega-Unit revealed by monazite and xenotime age dating

Autori
Balen, Dražen ; Horváth, Peter ; Finger, Fritz ; Konečný, Patrik

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Goldschmidt 2013 / - , 2013, 647-647

Skup
Goldschmidt 2013

Mjesto i datum
Firenca, Italija, 25.08.2013. - 30.08.2013

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
crustal evolution; monazite; xenotime; Tisia

Sažetak
The Slavonian Mountains (Pannonian Basin, Croatia) are the area of particular significance within Tisia Mega-Unit.This large unit, with complex internal structure, encompasses three huge southward dipping Alpine nappe systems that expose characteristic lithologies of south-eastern part of Pannonian Basin basement. Complexes of the central nappe system (i.e. Bihor) outcrop along the 5.5 km long, NNW–SSE trending Kutjeva+ka Rijeka transect. This transect is one of the most prominent geological cross-sections that reflects a complex history of the metamorphic and igneous evolution, giving insight into crustal evolutionary processes and their relationship to deformation and metamorphism. Our previous age dating of monazite from the representative rock complexes along Kutjevačka Rijeka transect, combined with geothermobarometric data, revealed complex structure and metamorphic history that includes a pre-Variscan (Ordovician to Silurian ; 444±19 and 428±25 Ma)and a Variscan (356±23 Ma) medium-grade metamorphism [1, 2]. The primary focus of this study is on surprisingly large extent of very low- to low-grade Alpine metamorphism recorded in the parametamorphic rocks (chloritoid and chlorite schists) along the transect. The Th–U–Pb age dating on xenotime grains within the chloritoid schist gave an average age of 120±36 Ma, peak metamorphic conditions reaching 3.5–4 kbar and 340–380 °C. The age of 219±81 Ma obtained on Yb-rich xenotime (inherited?) core domain(s), implies a possible existence of older low-grade metamorphic phase(s)[3]. Two distinct penetrative low-grade metamorphic foliations recorded in the chlorite schists are accompanied by existence of two populations of small (~3.5 μm) low-Th monazites, giving an average age 99±15 Ma. Histogram of obtained ages shows two peaks at 120 and 80 Ma while age modelling recognized two peaks at 113±20 and 82±23 Ma. Those ages argue against "stratigraphic doubts" that contradict Alpine metamorphism in the area. [1] Balen et al. (2006) Miner Petrol 87, 143–162. [2] Horváth et al. (2010) Lithos 117, 269–282. [3] Balen et al. (2013) Int J Earth Sci, in press.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

POVEZANOST RADA