Assessing the MIS 5.3 and MIS 5.1 sea-levels along the Tyrrhenian Sea coast of central Italy A challenge for ice volume models?

We present a reconstruction of the MIS 5e, MIS 5c, and MIS 5a marine terraces located in the central part of the tectonically uplifted Tyrrhenian Sea coast of central Italy, based on the combination of pedo-morpho-stratigraphical investigations and object-based image analysis (OBIA) applied to a LiDAR-based digital terrain model (DTM). Nine ⁴⁰Ar/³⁹Ar ages on detrital sanidine provide geochronological constraints to the terraces. Combined paleoecological, sedimentological, and geomorphological analyses precisely characterize paleoecological and bathymetrical conditions allowing us to identify the sea-level indicators and to assess the associated paleo-sea-levels at 39 ± 1, 29 ± 2, and 6.5 ± 1.5 m above present sea-level for the highstands of MIS 5e (MIS 5.5), MIS 5c (MIS 5.3), and MIS 5a (MIS 5.1), respectively. Assuming a global relative sea-level of +5.7 m for MIS 5.5, and a constant local uplift rate since 125 ka, we obtain a local relative sea-level (RSL) of 0 m for MIS 5.3 and − 16.5 m for MIS 5.1. By assessing the regional tectonic and isostatic contributions, we compare the reconstructed sea-level indicators with global estimates based on the conventional regression formulae applied to the δ¹⁸O record, highlighting a ∼ +30 and + 15 m misfit. Our results point at a strongly nonlinear relationship between oceanic temperature and ice volume during the transition period from the MIS 5e interglacial to the inception of the subsequent glacial stage.