The structure of the Pannonian basin is the result of distinct modes of Mid-Late Miocene extension exerting a profound effect on the lithospheric configuration, which continues even today. As the first manifestation of extensional collapse, large magnitude, metamorphic core complex style extension took place at the beginning of the Mid-Miocene in certain parts of the basin. Extrapolation of the present-day high heat flow in the basin, corrected for the blanketing effect of the basin fill, indicates a hot and thin lithosphere at the onset of extension. This initial condition, combined with the relatively thick crust inherited from earlier Alpine compressional episodes, appears to be responsible for the core complex type extension at the beginning of the syn-rift period. This type of extension is well documented in the northwestern Pannonian basin. Newly obtained deep reflection seismic and fission-track data integrated with well data from the southeastern part of the basin suggests that it developed in a similar fashion. Shortly after the initial period, the style of syn-rift extension changed to a wide-rift style, covering an area of much larger geographic extent. The associated normal faults revealed by industry reflection seismic data tend to dominate within the upper crust, obscuring pre-existing structures. However, several deep seismic profiles, constrained by gravity and geothermal modeling, image the entire lithosphere beneath the basin. It is the Mid-Miocene synrift extension which is still reflected in the structure of the Pannonian lithosphere, on the scale of the whole basin system. The gradually diminishing extension during the Late Miocene/Pliocene could not advance to the localization of extension into narrow rift zones in the Pannonian region, except some deep subbasins such as the Makó/Békés and Danube basins. These basins are underlain coincidently by anomalously thin crust (22–25 km) and lithosphere (45–60 km). Significant departures (up to 130 mW m −2 ) from the average present-day surface heat flow ( c. 90 mW m −2 ) and intensive Pliocene alkaline magmatism are also regarded as evidence for the initiation of two newly defined narrow rift zones (Tisza and Duna) in the Pannonian basin system. However, both of these narrow rifts failed since the final docking of the Eastern Carpathians onto the European foreland excluded any further extension of the back-arc region.

The East Carpathians Bend area has a very complex structure characterized by the presence of nappes, their post-tectonic cover and salt diapirs. The salt forming the studied diapirs is Early Miocene (Burdigalian) in age. After its accumulation the salt was more or less continuously involved in alternating extensional and compressional stages that deformed it from its original tabular position to the present-day diapir. Five stages of salt deformation have been established: initial, pre-nappe emplacement, nappe emplacement, post-nappe emplacement and Wallachian. During all of these stages the salt was configured into different shapes: it formed a truncated cone during the initial stage, a mushroom head during the prenappe emplacement stage, and an increasingly more tapered shape with nappe emplacement and during the post-nappe emplacement stages. Finally, it was squeezed out and refashioned by strike-slip faulting during the Wallachian compressional stage of Pleistocene age.

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