Submarine Geomorphology of the Southwestern Sardinian Continental Shelf (Mediterranean Sea): Insights into the Last Glacial Maximum Sea-Level Changes and Related Environments

Giacomo Deiana,Luciano Lecca,Rita Melis,Paolo Orrù,Valentino Demurtas,Mauro Soldati

doi:10.3390/w13020155

Giacomo Deiana, Luciano Lecca + Show 4 more

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https://doi.org/10.3390/w13020155

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Abstract

During the lowstand sea-level phase of the Last Glacial Maximum (LGM), a large part of the current Mediterranean continental shelf emerged. Erosional and depositional processes shaped the coastal strips, while inland areas were affected by aeolian and fluvial processes. Evidence of both the lowstand phase and the subsequent phases of eustatic sea level rise can be observed on the continental shelf of Sardinia (Italy), including submerged palaeo-shorelines and landforms, and indicators of relict coastal palaeo-environments. This paper shows the results of a high-resolution survey on the continental shelf off San Pietro Island (southwestern Sardinia). Multisensor and multiscale data—obtained by means of seismic sparker, sub-bottom profiler chirp, multibeam, side scan sonar, diving, and uncrewed aerial vehicles—made it possible to reconstruct the morphological features shaped during the LGM at depths between 125 and 135 m. In particular, tectonic controlled palaeo-cliffs affected by landslides, the mouth of a deep palaeo-valley fossilized by marine sediments and a palaeo-lagoon containing a peri-littoral thanatocenosis (18,983 ± 268 cal BP) were detected. The Younger Dryas palaeo-shorelines were reconstructed, highlighted by a very well preserved beachrock. The coastal paleo-landscape with lagoon-barrier systems and retro-littoral dunes frequented by the Mesolithic populations was reconstructed.

Highlights

Sea-level variations connected to climatic oscillations [1] cause changes in the landscape of coastal areas and continental shelves [2]
This study aims to obtain new insights into the palaeo-geographic evolution of the San Pietro continental shelf of southwestern Sardinia (Figure 1) during the last cold stage (MIS 2) by analysing erosional and depositional landforms formed during the Last Glacial Maximum (LGM) sealevel lowstand, as well as the palaeo-geographic coastal evolution connected to the LGM sea-levels
Posidonia oceanica is nearly absent in the western and northern coastal strips and is limited to small discontinuous areas, where seagrasses are visible on the rocks at 10–25 m depth

Summary

Introduction

Sea-level variations connected to climatic oscillations [1] cause changes in the landscape of coastal areas and continental shelves [2]. The comparative geomorphological analysis of emerged and submerged areas is effective for revealing the landand seascape changes [3,4]. The detailed reconstruction of the submerged coastal palaeo-landscape is useful to understanding the dynamics of the human population during the Last Glacial Maximum (LGM) [5,6]. This study aims to obtain new insights into the palaeo-geographic evolution of the San Pietro continental shelf of southwestern Sardinia (Figure 1) during the last cold stage (MIS 2) by analysing erosional and depositional landforms formed during the LGM sealevel lowstand, as well as the palaeo-geographic coastal evolution connected to the LGM sea-levels. Previous studies successfully applied the glacial-hydro-isostatic adjustment (GIA) models [12,13,14,15,16,17]

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