Paleo-sea-level indicators in the Southern Tyrrenian Sea: Insights into relative sea-level changes from the Last Glacial Maximum to the early Holocene

A relative sea-level (RSL) curve represents changes in sea level, typically at the scale of a sedimentary basin. It accounts for both global eustatic sea-level changes and local or regional factors, including tectonic vertical movements (subsidence or uplift), Glacial Isostatic Adjustment (GIA), ocean circulation, and climate. For the Central Mediterranean, several RSL curves have been proposed by integrating eustatic sea-level changes with GIA models; some of them also include corrections for local vertical movements since the Last Glacial Maximum (LGM). However, these curves rely on a limited number of geological and chronological markers distributed over timescales ranging from several hundred to several thousand years, which constrain their accuracy and resolution. This study identifies sea-level markers on high-resolution multichannel seismic profiles acquired in the Sant'Eufemia Gulf (SEG; southeastern Tyrrhenian Sea) and serves as a benchmark for sea-level changes. Integrating seismic data with calibrated radiocarbon dating of gravity cores reveals that these sea-level markers formed during the LGM and during subsequent sea-level rise. Paleo sea-level markers integrated with benthic foraminiferal assemblages and granulometric trends from core samples spanning 14.5 ka to the Holocene allow construction of a qualitative RSL curve for the southeastern Tyrrhenian region from the LGM to the Holocene using a multi-proxy approach. This is because the investigated area has experienced minimal long-term net vertical land movements, which simplifies the analysis of the impacts of RSL change on nearshore evolution. The RSL curve exhibits a non-linear pattern characterised by seven distinct step-like segments, each representing rapid sea-level rise events punctuated by intervals of stillstands or slight sea-level falls. This pattern indicates episodic accelerations and pauses in sea-level rise, reflecting complex interactions of glacial meltwater input and GIA. Subsequently, the RSL curve was compared with a suite of synthetic RSL curves generated by various GIA models covering the period from the LGM to the Holocene. Among these models, the ANU14-HV, ANU04-MED, and ANU14-LV demonstrate the closest match to our data. Our findings shed new light on RSL change for the Central Mediterranean from the LGM to the Holocene, improving predictive modelling capabilities and elucidating broader implications of climate change. Finally, the characteristics of the seismic data, combined with the rigorous and detailed workflow well described in this work, ensure reproducibility for future research focused on RSL change, including regions with tectono-sedimentary dynamics different from those of our study area.