Naslov
New constraints on the geochronology of the Moslavačka Gora crystalline massif in Croatia

Autori
Starijaš, Biljana ; Gerdes. Axel ; Balen, Dražen ; Tibljaš, Darko ; Mayer, Andreas ; Finger, Fritz

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

Izvornik
Knjiga sažetaka / Abstracts Book / Horvat, Marija - Zagreb : Hrvatski geološki institut, 2010, 153-154

ISBN
978-953-6907-23-6

Skup
4. Hrvatski geološki kongres s međunarodnim sudjelovanjem

Mjesto i datum
Šibenik, Hrvatska, 14.10.2010. - 15.10.2010

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Moslavačka Gora; Ordovician metagranite; Cretaceous Central Granite; Cretaceous LP/HT metamorphism

Sažetak
The Moslavačka Gora Massif in Croatia (MGM) is located about 50 km ESE of Zagreb. It covers an area of ~150 km2 and represents an important surface exposure of crystalline basement within the Tertiary sediments of the Pannonian Basin. In terms of the Alpine plate tectonic framework, the MGM has been long considered to be a major outcrop of Variscan crystalline basement of the South Tisia block. Recently, the MG is related to the so-called “Sava-Zone”, which is interpreted as the Cenozoic suture between Tisia and the Northern Dinarides. Our geochronological, geochemical and geothermobarometric data indicate that theMGMconsists of a Cretaceous S-type granite pluton intruding a Cretaceous low-pressure/high-temperature (LP/HT) metamorphic complex. The age of the LP/HT metamorphism is estimated at ~90–100 Ma using the method of electron microprobe based monazite dating. Laser ablation-sector field-inductively coupled plasma-mass spectrometry (LA-SF-ICPMS) based U-Pb dating on zircon gave 82±1 Ma for the Central Granite. The metamorphic complex of the MGM comprises mainly felsic anatexites and orthogneisses of granitic composition together with metapelites (paragneisses and mica schists) and minor amphibolites. Zircons from three different samples of metagranite were dated at 486±6 Ma, 483±6 Ma and 491±1 Ma, suggesting that most of the metamorphic complex represents an Early Ordovician granitic series. The Cretaceous regional metamorphism culminated in granulite facies conditions of ~750 °C and 3–4 kbar. A retrograde metamorphic event at lower amphibolite facies conditions overprinted the metamorphic complex. This event is probably related to the intrusion of the Central Granite. The southeastern sector of the massif was additionally affected by post-granitic, predominantly NE oriented shearing at greenschist facies conditions. As yet there is no clear evidence for Variscan events in the MGM. Mineral relics of a medium-pressure amphibolite facies metamorphism are preserved in amphibolites. They are older than the Cretaceous LP/HT regional metamorphism, but their age is presently unknown. Some indications for a Permian regional metamorphic event are provided by inherited zircons in the Central Granite that have been dated with a Permian age, and by Permian monazite relics found in metapelites. The Cretaceous high heat flow regime recorded in the MGM crystalline massif is unique in the subcrop of the Pannonian Basin and may be a local feature triggered by a mafic intrusion in the lower crust.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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