Neogene synrift and early postrift sedimentary facies and depositional environments: a review of basin evolution in the central Pannonian Basin

Neogene extension resulted in diverse basin fill successions in numerous subbasins of the Pannonian Basin. Differences between them include age, locally variable subsidence and accumulation rates, paleo-water depth, supressed/enhanced eustatic signals, position of unconformities, marine versus lacustrine basin fills. All these factors hinder correlation and the application of sequence stratigraphy remains challenging in rift basins. Based on recent assessment of formations and age constraints, here basin evolution is described in terms of tectonic sequences. Following earliest Miocene onset of extension and transtension the oldest preserved deposits are late Early Miocene, and the youngest synrift is early Late Miocene. Rift initiation in many small basins is manifested by slope aprons near master faults, paludal (coal-bearing) to fluvial deposition in centres to distal margins. Early rift climax is shown by very high accumulation rates of fan deltas interfingering with deep-lacustrine or marine shales. The “mid” Badenian flooding in the Paratethys was superimposed on expanding rift-climax basins, comprising coevally thick black shales and shallow-water carbonates. During the marine and subsequently lacustrine postrift lithological variability decreased. Due to regional sediment influx, accumulation rates were high and the basins gradually filled up. Spatial or temporal deviations during the postrift are due to coeval inversion events.