The internal deformation of the Praid salt diapir and implications for potential storage applications

The Praid salt diapir is located in the Transylvanian Basin, Romania and it stands out as one of the earliest discordant salt structures to be described. The salt that forms this structure was deposited during the middle Miocene salinity crisis. Under geological conditions, rock salt exhibits plasticity, resembling a fluid, leading to highly intricate folding patterns in its deformation. Understanding the evolution of salt structures holds significant importance for a number of industries such as the hydrocarbon industry or hydrogen storage. To utilize such formations for storage purposes, a comprehensive understanding of the deformation processes, impurity distribution, and mineral composition becomes crucial. These factors wield considerable influence on the overall rock properties. Certain diapiric salt formations within these areas hold potential as sites for hydrogen storage due to their substantial dimensions, reaching around ~3500m in size, and existing caverns within some of these formations. This investigation centers on analyzing the deformation of the Praid salt diapir. The site features a public-accessible salt mine and numerous surface salt exposures. Our study involves detailed mapping of both surface and subsurface areas, focusing on internal salt deformation, the nature and distribution of impurities, and exploring salt-sediment interaction where exposed. In our research, we utilized surface and underground mapping within the accessible salt mine, coupled with photogrammetry and LiDAR technology, to construct detailed 3D models capturing complex large-scale deformation patterns. The majority of the salt layers exhibit steep to near-vertical inclinations, with diverse orientations that suggest curtain-fold-like structures. Certain areas notably display signs of refolding. Within the salt, various impurities of differing origins exist, predominantly large-scale blocks composed of siltstone to sandstone slabs that have undergone boudinage. This study is part of an ongoing initiative aimed at evaluating both the potential and associated risks of implementing hydrogen storage projects within these salt formations or similar structures. Acknowledgements: The work of DD was financed through the Scientific Performance Scholarship, offered by Babes-Bolyai University, Cluj-Napoca.