Seismic reflection data driven tectono-sedimentary analysis and hydrocarbon field characterization of the Slovak part of the Transcarpathian Basin

This review describes the tectono-sedimentary framework of the Slovak part of the Transcarpathian Basin within the Pannonian Basin System, with an outlook on the existing hydrocarbon fields. The East Slovak Basin formed owing to complex interaction between the Alpine–Carpathian orogeny and the subsequent Neogene back-arc extension in a pull-apart basin setting. The structural fabric of the pull-apart basin is dominated by a large boundary fault and an associated horsetail structure. The coincidence of the trace of the main boundary fault with large Miocene rhyolite volcanic domes highlights the importance of volcano-tectonic interaction. The basin fill includes a remnant of a pre-rift Paleogene to Eggenburgian sequence as part of the Central Carpathian Paleogene Basin and the dominant synrift Lower–Middle Miocene (Karpatian to Sarmatian/Pannonian) strata belonging to the Transcarpathian Basin. The synrift depositional environments ranged from marine to deltaic (Karpatian–Badenian–Sarmatian), interrupted by occasional evaporitic sedimentation, to lacustrine to alluvial (Pannonian). The existing hydrocarbon finds show significant gas and minor condensate field segments, mainly reservoired in upper Badenian and Sarmatian sandstones. The data presented in this study suggest untapped hydrocarbon potential in the proximal and distal regions of the Northern Horsetail structure, where no hydrocarbon fields have been found to date.