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[1] The western Adriatic margin (eastern Mediterranean), part of the Apennine foreland, is characterized by a differentiated tectonic setting, showing high subsidence rates (up to 1 mm/yr) in the northern area and tectonic uplift (on the order of 0.3–0.5 mm/yr) in the southern part corresponding with the so-called Apulia swell. The central Adriatic marks the transition between these two areas. To calculate subsidence values, the stratigraphy of the central Adriatic has been investigated through the borehole PRAD1.2 (European project Profiles across Mediterranean Sedimentary Systems), the first continuous Quaternary marine record in the Adriatic basin (71.2 m long) reaching the top of Marine Isotope Stage 11 (MIS 11). Subsidence calculations were performed first by applying the backstripping procedure to PRAD1.2, in order to investigate the contribution of sediment load and tectonic driving forces to subsidence. Despite the large error bars, mostly caused by the uncertainties in paleowater depth reconstructions, the values obtained demonstrate that tectonics is the main driver for subsidence in this area. In order to better estimate the subsidence rates, an independent approach is introduced, based on the correlation of the present-day burial depth of past shorelines deposited during the main glacial lowstands, from MIS 2 to MIS 10. The average subsidence rate of about 0.3 mm/yr appears greater than the average sediment supply rate (0.15 mm/yr), and this fact explains the overall backstepping of the 100 kyr regressive depositional sequences on the margin. The results obtained help to improve the understanding of the regional tectonics and can be used for quantitative reconstruction of Quaternary sea level changes in the Adriatic region. In general, the paper shows that even a short (71 m) borehole across a relatively short time span (340 kyr) can be useful for subsidence calculations, provided that a high-resolution definition of its stratigraphy is available and a correlation can be drawn with the geomorphologic proxies such as paleoshoreline deposits.

[The Po River Lowstand Wedge (PRLW) of the central Adriatic Sea is made up of stacked alternated clinothems (Type A, B and C clinothems) that show different amount of aggradation of their topsets (e.g. Pellegrini et al., 2018). In this paper, we present novel sedimentological and paleontological analyses and discuss the processes responsible for the observed successions. We detail the character of the clinoforms deposited at the shelf‐edge, discussing the importance of hyperpycnal and storm‐enhanced sediment‐gravity flows in controlling the lithologic assemblage of the different tracts of the compound clinoforms. More in general, we show that, when the fine details of prograding clinoform units are investigated, the processes that lead to margin outbuilding are more complex than usually envisaged. , Abstract Clinoforms with a range of scales are essential elements of prograding continental margins. Different types of clinoforms develop during margin growth, depending on combined changes in relative sea level, sediment supply and oceanographic processes. In studies of continental margin stratigraphy, trajectories of clinoform ‘rollover’ points are often used as proxies for relative sea‐level variation and as predictors of the character of deposits beyond the shelf‐break. The analysis of clinoform dynamics and rollover trajectory often suffers from the low resolution of geophysical data, the small scale of outcrops with respect to the dimensions of clinoform packages and low chronostratigraphic resolution. Here, through high‐resolution seismic reflection data and sediment cores, we show how compound clinoforms were the most common architectural style of margin progradation of the late Pleistocene lowstand in the Adriatic Sea. During compound clinoform development, the shoreline was located landward of the shelf‐break. It comprised a wave‐dominated delta to the west and a barrier and back‐barrier depositional system in the central and eastern area. Storm‐enhanced hyperpycnal flows were responsible for the deposition of a sandy lobe in the river mouth, whereas a heterolithic succession formed elsewhere on the shelf. The storm‐enhanced hyperpycnal flows built an apron of sand on the slope that interrupted an otherwise homogeneous progradational mudbelt. Locally, the late lowstand compound clinoforms have a flat to falling shelf‐break trajectory. However, the main phase of shelf‐break bypass and basin deposition coincides with a younger steeply rising shelf‐break trajectory. We interpret divergence from standard models, linking shelf‐break trajectory to deep‐sea sand deposition, as resulting from a great efficiency of oceanographic processes in reworking sediment in the shelf, and from a high sediment supply. The slope foresets had a large progradational attitude during the late lowstand sea‐level rise, showing that oceanographic processes can inhibit coastal systems to reach the shelf‐edge. In general, our study suggests that where the shoreline does not coincide with the shelf‐break, trajectory analysis can lead to inaccurate reconstruction of the depositional history of a margin.]

[Conceptual stratigraphic section of the Po di Pila clinothem throughout the 4‐years bathymetric surveys. Bottom, year 2013: the Po di Pila shows compound progradation in the central sector, with a subaqueous Rollover Point (RP) at 8 m, whereas in the northern sector a single RP develops at an average of 3 m water depth. Center, year 2014: the Po di Pila shows compound progradation in both (central and northern) sectors, but a destruction phase in the central sector (eroded topset and RPs separated by a collapse depression) and a constructional phase in the northern sector (normal regression with compound clinothems) occur simultaneously. Top, year 2016: the Po di Pila shows a subaqueous RP at an average 5 m of water depth of the transverse bar in the central sector, whereas compound progradation is recorded in the northern sector. Note that in a subaerial delta, such as the modern Po Delta, subaerial RPs correspond to breaks in slope associated with the presence of mouth bars, whereas subaqueous nearshore RPs correspond to breaks in slope due to the presence of transverse bars and delta lobes. , Abstract Reconstructions of ancient delta systems rely typically on a two‐dimensional (2D) view of prograding clinothems but may miss their three‐dimensional (3D) stratigraphic complexity which can, instead, be best documented on modern delta systems by integrating high‐resolution geophysical data, historical cartography, core data and geomorphological reconstructions offshore. We quantitatively compare three precisely positioned, high‐resolution multi‐beam bathymetry maps in the delta front and pro delta sectors (0.3 to 10 m water depth) of Po di Pila, the most active of the modern Po Delta five branches. By investigating the detailed morphology of the prograding modern Po Delta, we shed new light on the mechanisms that control the topset to foreset transition in clinothems and show the temporal and spatial complexity of a delta and its pro delta slope, under the impact of oceanographic processes. This study documents the ephemeral nature of the rollover point at the transition between sandy topset (fluvial, delta plain to mouth‐bar) and muddy seaward‐dipping foreset deposits advancing, in this case, in >20 m of water depth. Three multibeam surveys, acquired between 2013 and 2016, document the complexity in space and time of the topset and foreset regions and their related morphology, a diagnostic feature that could not be appreciated using solely 2D, even very high‐resolution, seismic profiles. In addition, the comparison of bathymetric surveys gathered with one‐year lapses shows the migration of subaqueous sand dunes on the clinothem topset, the formation of ephemeral cut‐and‐fill features at the rollover point (few m below mean sea level), the presence of collapse depressions derived by sagging of sediments and fluid expulsion (possibly induced by storm waves) on the foreset, and splays of sand likely reflecting gravity flows on the lower foreset. Though the modern Po Delta is anthropogenic in many respects, its subaqueous clinothem can be studied as a scale model for ancient clinothems that are less resolved geometrically and far less constrained chronologically.]

Depositional systems accumulating under the combined influence of along-slope currents and downslope sediment-gravity flows are frequent in several continental margins. Despite being well-documented in terms of how these opposing depositional processes shape the margin architecture, many aspects related to their interaction and distinctive characters of resulting sediment accumulations remain elusive. Here we focus on the Gela Basin, the foredeep of the Maghrebian fold-and-thrust belt in the Strait of Sicily, where the Levantine Intermediate Water (LIW) and the Modified Atlantic Water (MAW) are confined by margin morphology, which amplify their velocities. Two sediment cores located on the upper and lower slope of the Gela Basin document the overlapping of along- and downslope processes since the very last phase of the Last Glacial Maximum (LGM). Detailed analysis of several proxies including sedimentary structures, sortable silt, geochemical elemental composition, oxygen and carbon isotopes, ichnofacies and foraminifera assemblages helped to disentangle the sedimentary imprints of contourites (including variations in bottom-current velocity through time) and downslope gravity-driven processes (turbidity currents and mass-transport processes). The slope experienced exceptionally high sedimentation rates up to 1300 cm kyr(-1) during the last phase of LGM and early phase of Heinrich Stadial 1 (F151), which rapidly decreased before Heinrich Event 1 (< 100 cm kyr(-1)). The high accumulation rates were driven by a combination of sediment input from the inner and mid shelf and lateral advection promoted by strong bottom-currents under the action of the LIW. An abrupt and brief intensification (+ 7.8 cm -1 ) of the MAW speed during the early phase of HSI affected the stability of the sediment drifts, which were growing since the previous interglacial and contributed to the emplacement of mass-transport deposits around 17 kyr BP. During the post-glacial sea-level rise pulses, before and during the Heinrich Event 1, the two sediment cores registered contrasting bottom-current velocities, suggesting a progressive shoaling of the LIW and modifications at the interface between the LIW and the MAW, in response to the increased fresh water discharge from the Atlantic. Our findings suggest that sea-level fluctuations can change the thickness and core-depth of the Central Mediterranean water masses, leading to intervals of enhanced bottom-current erosion and margin instability along the outer shelf and upper slope.

39 pages, 6 figures, 2 tables, This paper presents major gaps and challenges for implementing the UN Decade of Ocean Science for Sustainable Development (2021-2030) in the Mediterranean region. The authors make recommendations on the scientific knowledge needs and co-design actions identified during two consultations, part of the Decade preparatory-phase, framing them in the Mediterranean Sea’s unique environmental and socio-economic perspectives. According to the ‘Mediterranean State of the Environment and Development Report 2020’ by the United Nations Environment Programme Mediterranean Action Plan and despite notable progress, the Mediterranean region is not on track to achieve and fully implement the Sustainable Development Goals of Agenda 2030. Key factors are the cumulative effect of multiple human-induced pressures that threaten the ecosystem resources and services in the global change scenario. The basin, identified as a climate change vulnerability hotspot, is exposed to pollution and rising impacts of climate change. This affects mainly the coastal zones, at increasing risk of extreme events and their negative effects of unsustainable management of key economic assets. Transitioning to a sustainable blue economy is the key for the marine environment’s health and the nourishment of future generations. This challenging context, offering the opportunity of enhancing the knowledge to define science-based measures as well as narrowing the gaps between the Northen and Southern shores, calls for a joint (re)action. The paper reviews the state of the art of Mediterranean Sea science knowledge, sets of trends, capacity development needs, specific challenges, and recommendations for each Decade’s societal outcome. In the conclusions, the proposal for a Mediterranean regional programme in the framework of the Ocean Decade is addressed. The core objective relies on integrating and improving the existing ocean-knowledge, Ocean Literacy, and ocean observing capacities building on international cooperation to reach the “Mediterranean Sea that we want”, With the institutional support of the ‘Severo OchoaCentre of Excellence’ accreditation (CEX2019-000928-S)

This study presents novel findings on the Pliocene and Quaternary evolution of the Gela Basin (Strait of Sicily, Mediterranean Sea), an area recording the interaction between tectonics, climate change at Milankovitch and sub-Milankovitch timescales, and dynamic water masses exchange between the eastern and western Mediterranean Sea. The calibration of seismic profiles with exploration boreholes allowed for the refining of the chronostratigraphic framework of the Gela Basin and highlighted the main phases of margin growth. Since the Pliocene, the margin has recorded the deposition of 100 m high shelf-edge clinothems, accompanied by sediment drifts on the slope and mass-transport deposits (MTDs), possibly triggered by seismic activity. Through the Plio-Quaternary the locus of deposition of sediment drifts migrated upslope due to a progressive shift of bottom currents. After the Middle Pleistocene Transition (MPT) the margin experienced an accelerated outbuilding with the deposition of a 700 m thick succession in only 0.8 Myr. At this time, a marked change in sedimentary architecture reflects the growth of shelf-edge clinothems and associated MTDs on the slope, and the spreading of contourite deposits over a broader and generally shallower area. Sediment flux to the basin and the intensity of bottom currents appear both paced at 100 kyr eccentricity orbital cycles. The growth of bottom current deposits on a large portion of the upper slope and outer shelf likely reflects constraints to the bottom current flow by the margin morphology, inherited from Miocene and Pliocene tectonics. Overall, a combination of long-term tectonic activity, climate change and shifts in oceanographic regime resulted in a complex along-strike variability of the margin morphology and stratigraphic architecture and affected where and when MTDs were emplaced. These conclusions show how climate cyclicity influence sediment supply which combined with margin morphology can promote slope instability in continental margins.