Submerged geomorphic record of Quaternary palaeoshorelines: terraces and clinothems along a shelf‐edge in the Žirje Archipelago, Adriatic Sea

Numerous studies have shown that during the Quaternary there were substantial fluctuations in sea level in response to glacial–interglacial climate variability, reaching lowstand positions up to 134 m below the present sea level (b.s.l.). These fluctuations have had a strong influence on the morphology of shallow shelf seas, which preserve evidence of former terrestrial and coastal landscapes that are now submerged. Geomorphic analyses of submerged coastal landforms, such as marine terraces and clinothems, can thus provide valuable information regarding palaeoshoreline positions and insights into past sea levels. In this study, using high‐resolution acoustic methods, we investigated the Žirje Archipelago located along the central part of the karstified eastern Adriatic coast to detect the distribution and characteristics of submerged palaeoshorelines. The acquired data revealed a series of marine terraces at depths between 44.5 and 207.9 m b.s.l. Comparisons with available sea‐level curves show that these terraces formed during periods of sea‐level stillstands or decelerated rates of sea‐level rise, extending back to at least Marine Isotope Stage 10. In addition, progradational shelf‐edge delta clinoforms with rollover points at depths ranging from 127 to 131 m b.s.l. indicate the position of the shoreline during the Last Glacial Maximum (LGM). These features, observed on the slope towards the Mid‐Adriatic Deep, are interpreted as a lowstand wedge of the Late Pleistocene Krka River. By integrating information on erosional marine terraces and depositional clinothems, we propose new constraints on the evolution of Quaternary shorelines and variability in regional relative sea levels. Moreover, for the first time, we tentatively identify the position of the palaeoshoreline along the eastern Adriatic during the LGM. The surveyed area proved to be a natural laboratory for studying shelf‐edge environments adjacent to sediment‐starved karstified coasts.