Unraveling the Evolution of a Submerged Coastal Karst Basin in the Adriatic Sea: Insights from Geomorphology and Seismic Stratigraphy

Although recent studies have significantly improved our understanding of submerged landscapes along the karstified eastern Adriatic coast, many aspects of their evolution and response to post-glacial relative sea-level rise remain poorly understood. Thus, the present study offers new insights into the Late Quaternary paleoenvironmental history of Pirovac Bay, a submerged coastal karst basin in the central Adriatic, by integrating high-resolution seismic data with chronologically constrained sediment cores. The results revealed the existence of two morphologically distinct karst depressions that provided accommodation space for the formation of diverse depositional environments. The Late Glacial and Holocene sedimentary succession documents an evolution from subaerial and fluvially influenced settings to lacustrine and ultimately fully marine environmental conditions. The identified fluvio-karst valley highlights the largely unexplored role of fluvio-karst processes in the development of coastal karst basins, while the discovered Pirovac paleolake is the youngest submerged Holocene lake known along the eastern Adriatic coast. The present-day embayment appears to be characterized by erosional processes and active submarine groundwater discharge, reflecting highly dynamic hydrological conditions. These findings contribute to a better understanding of the interactions between karstification, sea-level rise, sedimentary processes, and groundwater dynamics in coastal karst basins. They also provide an important framework for future paleoenvironmental and hydrogeological investigations along the eastern Adriatic coast.