2 research outputs found
Paleogeographic evolution of the Southern Pannonian Basin: 40Ar/39Ar age constraints on the Miocene continental series of notthern Croatia
The Pannonian Basin, originating during the
Early Miocene, is a large extensional basin incorporated
between Alpine, Carpathian and Dinaride fold-thrust belts.
Back-arc extensional tectonics triggered deposition of up to
500-m-thick continental fluvio-lacustrine deposits distributed
in numerous sub-basins of the Southern Pannonian
Basin. Extensive andesitic and dacitic volcanism accompanied
the syn-rift deposition and caused a number of
pyroclastic intercalations. Here, we analyze two volcanic
ash layers located at the base and top of the continental
series. The lowermost ash from Mt. Kalnik yielded an
40Ar/39Ar age of 18.07 ± 0.07 Ma. This indicates that the
marine-continental transition in the Slovenia-Zagorje
Basin, coinciding with the onset of rifting tectonics in the
Southern Pannonian Basin, occurs roughly at the Eggenburgian/
Ottnangian boundary of the regional Paratethys
time scale. This age proves the synchronicity of initial
rifting in the Southern Pannonian Basin with the beginning
of sedimentation in the Dinaride Lake System. Beside
geodynamic evolution, the two regions also share a biotic
evolutionary history: both belong to the same ecoregion,
which we designate here as the Illyrian Bioprovince. The
youngest volcanic ash level is sampled at the Glina and
Karlovac sub-depressions, and both sites yield the same
40Ar/39Ar age of 15.91 ± 0.06 and 16.03 ± 0.06 Ma,
respectively. This indicates that lacustrine sedimentation in
the Southern Pannonian Basin continued at least until the
earliest Badenian. The present results provide not only
important bench marks on duration of initial synrift in the
Pannonian Basin System, but also deliver substantial
backbone data for paleogeographic reconstructions in
Central and Southeastern Europe around the Early–Middle
Miocene transition