Magnetostratigraphic, seismic and biostratigraphic correlations of the Upper Miocene sediments in the northwestern Pannonian Basin System

Magnetic polarity records from four wells and four surface outcrops from the non-marine Upper Miocene ofthe northwester, Pannonian Basin System have been correlated with the polarity time scale. Correlation between the wells (Duka-II, Nagylozs-1, Szombathely-II, and Zsira-1) was established by means of seven seismic horizons (A to G), calibrated biostratigraphically in the boreholes. Interpretation of the seismic horizons was extended to about 8000 km(2) in northwestern Hungary. Correlation of the surface outcrops was based on biostratigraphy (Hennersdorf, Pezinok, Sopron) or it was attempted by seismic stratigraphy (Berbaltavar). Although the Hennersdorf, Sopron, and Pezinok outcrops all belong to C5n (11.04 to 9.78 Ma), the first is biostratigraphically older than the latter ones. This correlation implies that the MN10 rodents of the Pezinok outcrop are older than 9.7 Ma, the presently acknowledged MN9/MN10 boundary. The borehole sections in the western part of the Kisalfold (Danube) Basin (Nagylozs, Zsira, and Szombathely) were correlated with Chrons C5r to C3B (> 11 Ma to > 7 Ma), whereas the Duka section in the southeastern part corresponded to the interval C4Ar to C4r (> 9 Ma to > 8 Ma). The Berbaltavar mammal locality probably correlates with C4n (8.11 to 7.53 Ma). All these data combined with facies interpretation and seismic correlations suggest that the shelf break of Lake Pannon swept across the Kisalfold Basin from NW to S-SE in less than 1 million year (ca. 9.7 to 8.8 Ma).