Abstract: Sequence Stratigraphy of the Neogene Pannonian Basin, Hungary

Gabor Vakarcs, Peter R. Vail, Gabor Tari, Scott Bowman, Peter Varnai

Few studies exist in the geologic literature that show the distribution of seismic facies and depositional sequences within a lacustrine basin. The Pannonian basin of Central Europe offers a unique opportunity to evaluate the influence of the eustatic signal on lacustrine deposition.

Seismic stratigraphic and sedimentological studies indicate that the middle Miocene-early Pliocene infill of the transtensional Pannonian basin was formed by large delta systems. Systematic sequence stratigraphic analysis of 7000 km of reflection seismic data and more than 100 hydrocarbon exploration wells in Hungary allowed the identification of twelve third-order sequence boundaries in the late Neogene sedimentary fill. This number of sequences corresponds to that of the published global eustatic curve for this time period. Furthermore, based on magnetostratigraphic and radiometric data, the ages of these sequences can be tentatively correlated with the global eustatic curve.

The Pannonian basin became isolated from the world sea at 10.5 Ma and formed a large lake. The stratal patterns and sedimentary facies of individual systems tracts within the lacustrine sequences display the same characteristics as marine depositional sequences. Moreover, an interesting sequence stratigraphic analogy can be drawn between the large low-stand deep-water fans of the Pannonian basin and the lowstand submarine fans of the Gulf of Mexico.

The geometry of sequences and systems tracts was simulated for the time interval of 12.5-3.0 Ma. This computer simulation indicates extremely high sediment input rates and considerable subaerial erosion of consecutive highstand systems tracts.

Few studies have addressed the problems of hydrocarbon exploration in a lacustrine basin within a sequence stratigraphic framework. Thus the case of the Pannonian basin may provide a useful analogue for exploration efforts worldwide in lacustrine basins.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994