Are the Oligocene-Middle Miocene Global Stages Depositional Sequences? A Correlation Study from the Pannonian Basin, Hungary

Gabor A. Vakarcs, Vitor Abreau, and Peter R. Vail

Based on the interpretation of 3000 km of 2D reflection seismic sections and 70 hydrocarbon exploration and production wells from the Pannonian Basin, combined with the analysis of available lithostratigraphic, sedimentologic, biostratigraphic, magnetostratigraphic data, eight regional stage boundaries were examined within the Central Paratethys.

All regional stages within the Central Paratethyan realm (Central/Eastern Europe) were originally identified by benthic foraminifera and/or mollusc in shelf environments and are defined by transgressive-regressive facies cycles. At the basin margin well-defined unconformities were observed at the base of the stages. However, within the basins, these unconformities become conformable. Working on seismic and well data, we found sequence boundaries, that correspond very well to the stage boundaries. These stages correlate within the Paretethyan region, from Austria to the Caspian realm, and show a direct correlation with the global stages. Thus we interpret the Paratethyan stage boundaries as sequence boundaries. We believe that these boundaries, the global stage boundaries, and the inde endently identified isotope peaks from DSDP cores reflect the same global event - the eustatic sea level fall.

The chronostratigraphic position of the sequence boundary depends on eustasy and tectonic subsidence. The events - eustatic sea level falls, dated at the conformities - are global, but the sequence boundaries are not exactly synchronous from basin to basin.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California