Integrated stratigraphy and sedimentary evolution of the Late Neogene sediments of the Hungarian Plain, Pannonian Basin

Abstract

The paper gives an overview about the latest results of integrated stratigraphic research of the Late
Neogene (Pannonian s.l.) post-rift sedimentary succession of the Hungárián Plain which represents the
central, therefore greatest and deepest part of the Pannonian Basin, Central Europe. A series of régiónál
composite seismic profiles were interpreted in the main routes of sediment supply into the basin from
the NW and the NE directions. As a conclusion it was stated that 3rd order cycles were förmed by
structural changes in the basiri while 4th order cycles were driven by large-scale climatic cycles of the
Milankovitch band or their multiples (100, 200, or 400 ky). The interrelations in terms of sequence
stratigraphy, sedimentology and biostratigraphy as well as their effect on the changes of depositional
facies during sedimentary evolution were drawn up by a set of geologic profiles. Among the studied 3rd
order cycles the Pa-3 sequence, deposited in the 6.8-9.1 My time frame forms a tectonostratigraphic cycle
and seems to play an important role in the evolution of the basin. This cycle represents a huge amount
of sediment yield and extremities in facies architecture driven by intra-Pannonian structural changes.
During its time frame, after the deposition of an extremely thick prograding to aggrading lowstand
wedge, renewed strike-slip movements (appr. 7.2-8.0 My) and tilting in somé areas generated a major
transgression and therefore relatíve laké levél rise first of all in the E part of the basin. In the W part of
the Hungárián Plain the larger delta system could keep up with the laké levél rise so aggradation
occured. Then the structural style completely changed and at S B Pa-4 (appr. 6.8 My) a strong relatíve
base levél drop occured all around the basin driven most probably by the onset of inversion in the coeval
marginal areas of the basin much earlier than it was thought before. Sedimentation continued at a lower
base levél from this point on. This phenomena can be seen all around the Hungárián Plain, moreover
alsó in the Dráva Basin, based on independent interpretations of sequence stratigraphy by seismic data
and facies architecture studies by well logs.