## 6 Seismic Profiles  
The structural-stratigraphic analysis was supported by a regional 2D depth-migrated seismic reflection profile, trending NE-SW, that was acquired in the vicinity of the study area. The IO17-12 seismic line, presented here, was acquired during the IO17 2D Seismic Campaign, which concluded in 2019. The IO17 Campaign was part of the contractual obligation for the first exploration phase for the Ioannina Concession under the Operatorship of Repsol Exploration Ioannina S.A. Greek Branch on behalf of the Repsol S.A. and Energean Oil & Gas joint venture. The acquired 2D seismic data were subsequently processed in Repsol's Subsurface Imaging center in Houston, U.S.A. (for details, see Appendix A). The data-driven interpretive processing sequence that resulted in the final 2D Kirchhoff Pre-Stack Depth Migrated Section, presented in Figure 12, was meticulously formulated, revised, and modified under the Repsol Exploration Department's supervision, incorporating all available information (well data, surface formation dip measurements along all IO17 seismic line tracks, etc.). Following the same approach, seismic interpretation was conducted honoring all available hard data (such as surface geological mapping and dip measurements, surface fault traces, well tops, etc.).  
In summary, the processing objectives were as follows:  
* Improve on the seismic image in the time domain (PSTM).
* Focus on the structural image in all areas of the sections.
* Provide consistency between datasets, from both legacy and new IO17 seismic acquisitions.
* Provide PSDM images and a pseudo-3D regional velocity model consistent with surface geology and well velocities.  
The seismic profile depicts the regional structure up to a depth of 6 km. The upper part of the profile was seismically noisy and not much information was provided from that; thus, more surface structural data were needed to complement and complete the seismic profile structure. The complete Triassic to Eocene carbonate sequence was affected by the compressional deformation, developing an imbricate thrust system, consisting of thrusts that route and merge on a low-angle recollement horizon, represented by the evaporites. Along the eastern part of the recollement horizon, salt appears to be sheared and a salt weld marks the detachment from its source layer. This can provide some evidence that below that structural level in the basement there must be a thicker feeder evaporitic unit, from which the intrusive diapiric structure developed along the thrust surface. Alternatively, the basement can be a thrust-duplex structure of the Ionian unit or carbonates of the Pre-Apulian unit [102]. To the west, the fore-thrust brings the evaporites and Triassic breccia formation over a recumbent syncline fold that forms part of the overturned forelimb of a larger-scale, asymmetric to the west, box-type fold that is cored by the intrusive evaporites and Triassic breccia. A similar structural style can be seen further north in the exposed Dumre diapir in Albania, where diapirism is linked to a regional overhrrusting to the west, truncating an overturned syncline consisting of Jurassic-to-Paleogene strata below the western evaporite thrust margin [103; 104].  
Figure 12: (**A**) Seismic line extent in the study area (red line). (**B**) Interpretation overlaid on the IO17-12 seismic line (?: Unknown rock type).