Large and medium-scale morpho-sedimentary features of the Messina Strait: insights on bottom-current controlled sedimentation and interaction with downslope processes

The Messina Strait is a ∼ 3-8 km wide and 40 km-long extensional area that connects the Tyrrhenian Sea with the Ionian Sea (Mediterranean Sea), and where tectonics, oceanographic and erosive-depositional downslope processes strongly interact each other. Based on the analysis of high-resolution multibeam data, we present an updated morpho-sedimentary framework that reveals a complex seabed morphology, characterized by a variety of features linked to bottom-currents and downslope processes. In particular, we recognize a suite of large to medium-scale erosive and depositional features, related to different bottom-currents (e.g., reverse tidal flows, residual flows, internal waves) acting over diverse time periods. Large scale bottom-current features are represented by contourite drifts and channels developed over long periods (> thousands of years). Medium-scale features formed during shorter time periods and include scours, furrows, transverse ridges (pinnacles) and narrow longitudinal bodies in the sill sector, along with several sand wave fields, located at greater depths on the Ionian and Tyrrhenian sides of the Messina Strait. Downslope processes encompass channelized features originated by sedimentary gravity flows, coarse-grained aprons and fans and submarine landslides. They mostly occur along strait margins and become predominant in the southern exit where the axial Messina canyon and its tributaries are present.Overall, our study shows that the MS is a fruitful area in which to investigate the interaction between recent erosive-depositional sedimentary and oceanographic processes, also modulated by sea-level fluctuations, during the last eustatic cycle. Moreover, the observed seabed morphologies and the associated processes provide insights for interpreting similar features in modern and ancient similar straits and seaways.

New Evidence of MIS 3 Relative Sea Level Changes from the Messina Strait, Calabria (Italy)

Investigation of sea-level positions during the highly-dynamic Marine Isotope Stage 3 (MIS 3: 29–61 kyrs BP) proves difficult because: (i) in stable and subsiding areas, coeval coastal sediments are currently submerged at depths of few to several tens of meters below the present sea level; (ii) in uplifting areas, the preservation of geomorphic features and sedimentary records is limited due to the erosion occurred during the Last Glacial Maximum (LGM) with sea level at a depth of −130 m, followed by marine transgression that determined the development of ravinement surfaces. This study discusses previous research in the Mediterranean and elsewhere, and describes new fossiliferous marine deposits overlaying the metamorphic bedrock at Cannitello (Calabria, Italy). Radiocarbon ages of marine shells (about 43 kyrs cal BP) indicate that these deposits, presently between 28 and 30 m above sea level, formed during MIS 3.1. Elevation correction of the Cannitello outcrops (considered in an intermediate-to-far-field position with respect to the ice sheet) with the local vertical tectonic rate and Glacial Isostatic Adjustment (GIA) rate allows the proposal of a revision of the eustatic depth for this highstand. Our results are consistent with recently proposed estimates based on a novel ice sheet modelling technique.

New Evidence of MIS 3 Relative Sea Level Changes from the Messina Strait, Calabria (Italy)

Investigation of sea-level positions during the highly-dynamic Marine Isotope Stage 3 (MIS 3: 29-61 kyrs BP) proves difficult because: i) in stable and subsiding areas, coeval coastal sediments are currently submerged at depths of few to several tens of meters below present sea level; ii) in uplifting areas, the preservation of geomorphic features and sedimentary records is limited due to the erosion occurred during the Last Glacial Maximum (LGM) with sea level at depth of -130 m, followed by marine transgression that determined the development of ravinement surfaces. This study discusses previous research in the Mediterranean and elsewhere, and describes new fossiliferous marine deposits laying on metamorphic bedrock of Cannitello (Calabria, Italy). Radiocarbon ages of marine shells (about 43 kyrs cal BP) indicate that these deposits, presently between 28 and 30 meters above sea level, formed during MIS 3.1. Elevation correction of the Cannitello outcrops (considered in an intermediate-to-far-field position with respect to the ice sheet) with the local vertical tectonic rate and Glacial Isostatic Adjustment (GIA) rate allows to propose a revision of the eustatic depth for this highstand. Our results are consistent with recently proposed estimates based on a novel ice sheet modelling technique.

The More You Search, the More You Find: A New Mediterranean Endemism of the Genus Ocenebra Gray, 1847 (Mollusca: Gastropoda: Muricidae) from a Submarine Cave of the Messina Strait Area (Italy)

Three hundred years of study on the Mediterranean molluscan fauna led the scientific community to consider it as the best ever known. However, the rate at which new taxa are discovered and described every year is still remarkably high, even in key predators such as Muricidae Rafinesque, 1815. Within this family, the genus Ocenebra Gray, 1847 comprises species widely distributed in the northeastern Atlantic and the Mediterranean Sea that were already the target of a decadal nomenclatural, morphological, and molecular combined research. Notwithstanding, we hereby describe an additional ocenebrid endemism from the Mediterranean Sea, whose distribution appears to be restricted to a circalittoral submarine cave of the Messina Strait area (Italy). The new species Ocenebra vazzanai is compared with the recent Atlanto-Mediterranean congeneric taxa on the basis of the known type materials, and a table summarizing the main diagnostic features of the species is offered to facilitate future identifications. The high biodiversity highlighted in the genus Ocenebra reveals a wide adaptive radiation and suggests the necessity of further studies aiming to tackle biodiversity issues even in popular groups, such as molluscs, and in widely studied biogeographic areas, such as Italy, and the Mediterranean basin in general.