Shortened salt-withdrawal minibasins and associated salt welds are exposed in the Mesozoic strata of the Northern Calcareous Alps fold-and-thrust belt (Austria). Geological mapping and sequential restoration of a balanced cross section have indicated that these salt and salt-related structures developed during the postrift stage of the Neo-Tethys continental margin by evacuation and inflation/deflation of uppermost Permian to lowermost Triassic salt. Middle to Late Triassic minibasins were formed by down-building and downslope translation, flanked by megaflaps and salt walls. Salt and salt structures were rejuvenated by salt-wall fall and formation of bowl minibasins as a response to Penninic rifting since Rhaetian times. Complex structural styles, including younger-on-older contacts, tight folds, and kilometer-scale fully overturned panels resulted from the shortening of early salt structures upon the onset of Jurassic regional convergence. Salt tectonics can reconcile the stratigraphic development and internal structure of the long-debated Northern Calcareous Alps. Our work also provides a new line of research for understanding other fold-and-thrust belts developed from the Neo-Tethys continental margin (i.e., the Carpathian Mountains, the Southern Alps in Europe, the Dinaric Alps) and sets guidelines for other salt-influenced fold belts.

In this paper, different control approaches for grid-forming inverters are discussed and compared with the grid-forming properties of synchronous machines. Grid-forming inverters are able to operate AC grids with or without rotating machines. In the past, they have been successfully deployed in inverter dominated island grids or in uninterruptable power supply (UPS) systems. It is expected that with increasing shares of inverter-based electrical power generation, grid-forming inverters will also become relevant for interconnected power systems. In contrast to conventional current-controlled inverters, grid-forming inverters do not immediately follow the grid voltage. They form voltage phasors that have an inertial behavior. In consequence, they can inherently deliver momentary reserve and increase power grid resilience.

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Subsidence analysis study for several Triassic carbonate platforms from the eastern Northern Calcareous Alps shows that salt expulsion allowed for the growth of thick isolated depocentres (>1.5 km) at rates faster than those tectonic subsidence alone can provide. Our results, in addition to independent regional geological evidence, argue against previous models of thickskinned extension controlling accommodation space. Differential sedimentary loading and stretching of the salt layer can explain the development of the Triassic isolated carbonate platforms in the Northern Calcareous Alps, with salt expulsion being proportional to the growth potential of the carbonate producers. Aside of topographic loads, early diageneses of carbonates allow for the density inversion between sediment and salt, with differential loading by carbonate aggradation leading to a self-sustained feedback cycle of density-driven and gradient load subsidence; stretching of the salt layer and extensional deformation of its overburden, as constrained by cross-section restoration, also contributed to diapir initiation and salt expulsion. Our model can: (a) explain the occurrence of isolated Middle Triassic carbonate platforms in the eastern Northern Calcareous Alps, and (b) differentiate between accommodation space controlled by (local) salt expulsion and by (regional) tectonic subsidence. The Triassic Neo-Tethys shelf of the studied area constituted therefore a salt wall and minibasin province. This contribution and methods herein can also be applied to other carbonate platform systems developed on salt basins, especially where the transition from rift to drift remains unclear.

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For the first time, a concise lithostratigraphic scheme for the lower and middle Miocene (Ottnangian – Badenian) of the northern and central Vienna Basin is proposed, which is based on the integration of core-material, well-log data and seismic information from OMV. For all formations and members type sections are proposed, geographic distribution and thickness are provided, typical depositional environments and fossils are described and age constraints are discussed. This time frame allows for a more reliable calculation of sedimentation rates. This in turn might be important for the reconstruction of the tectonic history of the Vienna Basin as we do not see fundamental differences between the piggy-back stage and the subsequent pull-apart regime. Following lithostratigraphic units are formalized herein and/or are newly introduced: Bockfließ Formation (Ottnangian), Aderklaa Formation, Gänserndorf Member and Schönkirchen Member (Karpatian), Baden Group, Rothneusiedl Formation and Mannsdorf Formation (lower Badenian), Auersthal Formation, Matzen Formation, Baden Formation, Leitha Formation (middle Badenian) and Rabensburg Formation (upper Badenian).

We present a series of 2D thermo-mechanical numerical experiments of thick-skinned crustal extension including a pre-rift salt horizon and subsequent thin-, thick-skinned, or mixed styles of convergence accompanied by surface processes. Extension localization along steep basement faults produces half-graben structures and leads to variations in the original distribution of pre-rift salt. Thick-skinned extension rate and salt rheology control hanging wall accommodation space as well as the locus and timing of minibasin grounding. Upon shortening, extension-related basement steps hinder forward propagation of evolving shallow thrust systems; conversely, if full basin inversion takes place along every individual fault, the regional salt layer is placed back to its pre-extensional configuration, constituting a regionally continuous décollement. Continued shortening and basement involvement deform the shallow fold-thrust structures and locally breaches the shallow décollement. We aim at obtaining a series of structural, stratigraphic and kinematic templates of fold-and-thrust belts involving rift basins with an intervening pre-rift salt horizon. Numerical results are compared to natural cases of salt-related inversion tectonics to better understand their structural evolution.

The evolution of the early/middle Miocene Fohnsdorf Basin has been studied using borehole data, reflection seismic lines, and vitrinite reflectance. The basin is located along the sinistral Mur-Mürz fault system and probably formed as an asymmetric pull-apart basin, which was subsequently modified by halfgraben tectonics, as a consequence of eastward lateral extrusion. Sedimentation started with the deposition of fluvio-deltaic sediments. Thick coal accumulated in the northwestern basin. Thereafter subsidence rates increased dramatically with the formation of a lake several hundred meters deep. The lake was filled mainly from the north with more than 1500 m of sediments showing a coarsening-upward trend due to southward prograding deltaic lobes. A sequence of more than 1000 m of boulder gravels (Blockschotter) in the southeastern part of the basin are interpreted as the upper part of a coarse-grained fan delta succession, which accumulated along a normal fault along the southern basin margin. Fan deltas reached the central basin only during the early stages of sedimentation and during the late stages of basin formation. Miocene heat flow was approximately 65±70 mW/m 2 , which is significantly lower than in other basins along the Mur-Mürz fault system. The present-day southwestern basin margin is a recent feature, which is related to transpression along the dextral Pöls-Lavanttal fault system. It is formed by reverse faults constituting the northeastern part of a flower structure. Miocene sediments in the Feeberg valley are preserved along its southwestern part. Uplift of the central part of the flower structure was at least 2.4 km. North± south compression resulted in the deformation of the basin fill, uplift of the E/W-trending basement ridge separating the Fohnsdorf and Seckau basins, and in the erosion of 1750 m of sediments along the northern basin margin.