Geomorphological evidence of the Malta-Sicily land-bridge during the Last Glacial Maximum inferred from seismic profiles

Abstract

The Last Glacial Maximum (LGM) witnessed substantial sea-level fluctuations profoundly impacting the geomorphological evolution of the Maltese Islands, located in the SW part of the Malta Plateau (central Mediterranean Sea). It is known that during that period, a land-bridge connected the Maltese Islands to Sicily. However, discerning detailed geomorphological evidence of past sea-level changes in offshore regions proves difficult due to the limited availability of high-resolution multibeam bathymetry data, subsurface seismic profiles and potential tectonic influences. By addressing these challenges, this study sets out to meticulously reconstruct the coastline of the Malta Plateau and to delineate the extent of the land-bridge connecting Malta to Sicily during the LGM. The study was conducted by exploiting 2D multichannel seismic profiles acquired during oil exploration seismic surveys carried out offshore Malta and EMODnet bathymetry data. This analysis enabled the recognition of the coastline of the western side of the land-bridge connecting Malta and Sicily during the LGM, at a depth ranging from 119 to 131 m b.s.l. Uncertainties about the location of the eastern coastline remain due to the quality and extent of the seismic profiles and to the more intense morphodynamics of the Malta Plateau. A coastal lagoon system, bounded offshore by a barrier corresponding to a structural high, was recognized. During transgressional phases, the emerged LGM landscape was progressively submerged and locally sealed by a thin layer of sediments, which still preserves the most significant geomorphological features. With reference to the stratigraphic sequence, two facies were distinguished, the lower one interpreted as the pre-Plio-Quaternary (pre-PQ) sequence outcropping in Malta, and the upper one consisting of Plio-Quaternary (PQ) deposits onlapping on the former one. These results provide valuable insights into the palaeoenvironmental history of the region, contributing to a broader understanding of sea-level dynamics and geological evolution in the tectonically complex Mediterranean area.