Seismic stratigraphy based chronostratigraphy (SSBC) of the Serbian Banat region of the Pannonian Basin

Abstract

AbstractSeismic stratigraphy based chronostratigraphic (SSBC) analysis of the Serbian Banat region allows the delineation of the spatial and stratigraphic relationships of the generally regressive and shallowing upward Neogene depositional fill of a tectonically unstable central portion of the Pannonian Basin. When geometrically restored in time and space, the sediment dispersal directions, sediment source directions, types of sedimentation breaks and the tectonic events influencing basin evolution can be delineated. For such an analysis the time-transgressive lithostratigraphic units used in the neighbouring Hungarian part of the Pannonian Basin are conveniently introduced based upon their characteristic seismic facies and constrained borehole log records as mappable seismic stratigraphic sequence units, termed “seismic operational sequences”. The respective Neogene stage and operational sequence equivalents (Hungarian lithostratigraphic units or formations) are the Middle Miocene (Badenian, Sarmatian), Upper Miocene-Lower Pliocene (Pannonian-Endrod and Szolnok Formations; Pontian- Algyo and Ujfalu Formations and Lower Pliocene- Zagyva Formation) and Upper Pliocene-Quaternary (Nagyalfold Formation).SSBC analysis greatly assists in the geological constraint or “geovalidation” of interpreted seismic stratigraphic relationships and provides potentially critical insight into stratigraphic and structural problems of non-unique interpretations. In the specific case, using such an approach on previously unpublished regional seismic lines, SSBC analysis reveals that the Banat region has undergone structural inversion. This may be related to changes in local stress directions along strike slip faults, which initiated in earliest Late Miocene (Endrod Formation), culminating in the reverse tilting and incipient shortening of the western graben. Therefore during the time interval that the Badenian through Endrod sediments were deposited in the graben, autocyclic progradation initiated from the Kikinda Szeged High in the East followed by Szolnok, Algyo, Ujfalu and younger units prograding from the West as the central high uplifted relative to the graben. Such tectonic inversion has substantial hydrocarbon potential implications for exploration in the region.