Two-dimensional modelling of stratigraphy and compaction-driven fluid flow in the Pannonian Basin

Abstract

Abstract During the Pliocene-Quaternary time interval, the peripheral parts of the Pannonian Basin system have been uplifted and subsidence in the basin centre accelerated, causing a distinctive truncation pattern in the basin stratigraphy. Stress analyses indicate that the Pannonian Basin system, originally formed in an extensional regime, is subjected to a compressive stress since the early Pliocene. Results of forward modelling of basin subsidence and sedimentary filling along a cross-section through the southern part of the Pannonian Basin demonstrate that a change of the basin shape due to the compressive stress can successfully explain the observed pattern of differential uplift and subsidence occurring since the early Pliocene. In addition, the forward modelling of subsidence and fill provides constraints for the depth of lithospheric necking during extension, the palaeowater-depth history and lake-level changes in the southern part of the Pannonian Basin. Compaction-driven fluid flow modelling shows that the first significant overpressures in the southern part of the Pannonian Basin developed during progradation of a large deltaic system, at a time when sedimentation rates increased rapidly. Due to the stress-induced acceleration of subsidence during Pliocene to Quaternary times, sedimentation rates increased again, causing a further increase of overpressure. The Pliocene stress induced uplift of the basin flanks combined with a preceding lake-level fall created a larger gravity potential of the groundwater table, enhancing the influx of meteoric water into the basin. This can explain observed diagenetic patterns in the southern part of the Pannonian Basin.