Imaging continental shelf shallow stratigraphy by using different high-resolution seismic sources: an example from the Calabro-Tyrrhenian margin (Mediterranean Sea)

High-resolution seismic reflection profiles of the Calabro-Tyrrhenian continental shelf were collected using different seismic sources (Sub-Bottom Profiler, Uniboom, Sparker 0.5-1-4.5 kJ). Noticeable differences and results were obtained both from a geophysical and geological-interpretative point of view. The availability of different sources permitted the definition of the most suitable seismostratigraphic characterization in terms of resolution, penetration and acoustic facies. Very high resolution stratigraphy was defined through profiles produced by different seismic systems used in parallel. This permitted the application of sequence-stratigraphy concepts with the reconstruction of a thick postglacial depositional sequence, formed by a transgressive and a high-stand systems tract. The thickness distribution of postglacial deposits reveals that the main depocenter (55-65 m) is located offshore of the Coastal Range, along a stretch of coast supplied by several small and seasonal streams ("fiumare") and characterized by the lack of a coastal plain. This suggests the greater efficiency of sediment supply and bypass in this area relatively to sectors located offshore of the main rivers. The transgressive systems tract, usually thin or nearly absent, is particularly well developed (up to 33 m) and is composed of up to three parasequences with a retrogradational stacking pattern. The high-stand systems tract, up to 30 m thick, is made up of two parasequences and has a quite regular geometry and acoustic facies

Straits and seaways: end members within the continuousspectrum of the dynamic connection between basins

Straits and seaways are fundamental connectors of oceans, seas and more rarely lakes. They areubiquitous in the modern geography and should be common in ancient landscapes. We compare their charac-teristics to improve our understanding of these features, with the aim to define better their geological use.We review geomorphological, oceanographic, geological and depositional characteristics based on well-doc-umented modern and ancient examples, with a stronger focus on the rock record.‘Strait’and‘seaway’are differentiated by their spatial and temporal scale. This influences the type and per-sistence of oceanographic circulation and sediment distribution. Straits are individual depositional systems,with predictable bedform and facies changes along the sediment transport pathway, whereas seaways are largerand longer-lived physiographic domains, composed of numerous depositional systems. Therefore, their strati-graphic signature in the rock record should be significantly different. We conclude that straits and seaways areend members of a continuum, giving rise to the occurrence of intermediate cases with transitional characteris-tics. The distinctive geological usage of the terms‘strait’and‘seaway’, even without sharp boundaries betweenend members, may be helpful for predicting their occurrence, stratigraphy, palaeogeography, biota distributionand potential distribution of reservoirs and seals for fossil resources and CO2storage

Benthic foraminiferal assemblages and rhodolith facies evolution in post-LGM sediments from the Pontine Archipelago shelf (Central Tyrrhenian Sea, Italy)

The seabed of the Pontine Archipelago (Tyrrhenian Sea) insular shelf is peculiar as it is characterized by a mixed siliciclastic–carbonate sedimentation. In order to reconstruct the Late Quaternary paleoenvironmental evolution of the Pontine Archipelago, this study investigates the succession of facies recorded by two sediment cores. For this purpose, benthic foraminifera and rhodoliths assemblages were considered. The two cores (post-Last Glacial Maximum in age) were collected at 60 (CS1) and 122 m (Caro1) depth on the insular shelf off Ponza Island. The paleontological data were compared with seismo-stratigraphic and lithological evidence. The cores show a deepening succession, with a transition from a basal rhodolith-rich biodetritic coarse sand to the surface coralline-barren silty sand. This transition is more evident along core Caro1 (from the bottom to the top), collected at a deeper water depth than CS1. In support of this evidence, along Caro1 was recorded a fairly constant increase in the amount of planktonic foraminiferal and a marked change in benthic foraminiferal assemblages (from Asterigerinata mamilla and Lobatula lobatula assemblage to Cassidulina carinata assemblage). Interestingly, the dating of the Caro1 bottom allowed us to extend to more than 13,000 years BP the rhodolith record in the Pontine Archipelago, indicating the possible presence of an active carbonate factory at that time

New evidences of the interplay between a turbidite canyon (Guadiaro canyon, NW Alboran Sea) and current-driven along slope processes

Workshop. Alboran Domain and Gibraltar Arc: Geological Research and Natural Hazards - El dominio de Alborán y el Arco de Gibraltar: Investigación geológica y riesgos naturales - Le Domaine Alboran et l'Arch de Gibraltar: Recherche géologique et risques naturels, 16-18 octubre 2019, Granada..-- 2 pages, 1 figureThe NW Alboran Sea contains geological evidences of the intricate interplay of downslope and alongslope features on one hand, and of the interaction of the Atlantic Waters flowing out and the intermediate Mediterranean Waters (MWs) flowing into the Strait of Gibraltar on the other hand.Both of these interactions are of high scientific relevance and have been studied separately before, but must also be considered together since both phenomena occur simultaneously. The work is based on data acquired during the FAUCES surveys, comprising high-resolution bathymetry and seismic profiles, in combination with a database comprising seismic profiles acquired since the 70s. The interaction between downslope and alongslope processes occurs on both margins of the Alboran Sea, but this interaction is especially complex in the Spanish margin, where the turbidite canyons cut the continuity of terraced plastered drifts. The interaction may vary between the dominance of downslope processes over the alongslope processes (i.e., Almeria turbidite system), the alternation between downslope and alongslope deposits (which is the case of the most recent lobe of the Guadiaro fan) and the influence of alongslope processes over downslope processes. The Guadiaro canyon provides an example of the last case: After a first phase in which the canyon was incised, during a second phase (Pliocene) downslope processes were dominant, as indicated by the chaotic facies infilling the canyon incision. A last phase (Quaternary) characterized by stratified discontinuous facies indicate a greater influence of contourite alongslope deposits. During the stage two and mostly during stage three, the lateral accretion of packages (LAPs) of stratified facies with NE progradation trend have been recognized on its SW side (right margin), progressively invading of the Guadiaro Palaeocanyon and affecting its current location and shape (Fig. 1). These findings have been confirmed by isochore maps, in which a depocentre of Quaternary age runs parallel to the canyon on its SW side. The oceanography of the study area is marked by the closeness to the Strait of Gibraltar, located to the west. The Mediterranean intermediate waters, comprising Western Intermediate Waters (WIW), Levantine Intermediate Waters (LIW) and the upper portion of Tyrrhenian Dense Waters (TDWi), flow along the Spanish margin towards the Strait. On the opposite, the Atlantic Waters enter forming a strong jet into the Mediterranean. These two groups of water masses are separated by a pycnocline, along which internal waves formed in the Camarinal Sill travel eastwards. The NE progradation of the LAPs affecting the Guadiaro canyon points to the much stronger effect of the Atlantic Jet and the eastwardtravelling internal waves over the intermediate MWs directed towards the Strait of Gibraltar. Ultimately, these findings may shed light on one of the reasons behind the sudden abandonment and obliteration of the Estepona Palaeocanyon after the BQD, possibly located where the Atlantic Jet and the internal waves cease their sediment transport towards the NE and where the weaker SW transport by the intermediate Mediterranean Waters become the only alongslope transport mechanismContribution from Project FAUCES - CTM2015-65461-C2-R (MINECO/FEDER

Understanding the complex geomorphology of a deep sea area affected by continental tectonic indentation: The case of the Gulf of Vera (Western Mediterranean)

19 pages, 11 figures, 1 table, supplementary data https://doi.org/10.1016/j.geomorph.2022.108126.-- Data availability: Casas, D., & UTM-CSIC. (2018). FAUCES-1 Cruise, RV Sarmiento de Gamboa [Data set]. UTM-CSIC. doi: 10.20351/29SG20170925 Comas, M. & UTM-CSIC. TOPOMED-GASBATS. Cruise, RV Sarmiento de Gamboa [Data set]. UTM-CSIC.doi: 10.20351/29SG20120517We present a multidisciplinary study of morphology, stratigraphy, sedimentology, tectonic structure, and physical oceanography to report that the complex geomorphology of the Palomares continental margin and adjacent Algerian abyssal plain (i.e., Gulf of Vera, Western Mediterranean), is the result of the sedimentary response to the Aguilas Arc continental tectonic indentation in the Eurasian–Africa plate collision. The indentation is imprinted on the basement of the margin with elongated metamorphic antiforms that are pierced by igneous bodies, and synforms that accommodate the deformation and create a complex physiography. The basement is partially covered by Upper Miocene deposits sealed by the regional Messinian Erosive Surface characterized by palaeocanyons that carve the modern margin. These deposits and outcropping basement highs are then covered and shaped by Plio-Quaternary contourites formed under the action of the Light Intermediate and Dense Deep Mediterranean bottom currents. Even though bottom currents are responsible for the primary sedimentation that shapes the margin, 97% of this region's seafloor is affected by mass-movements that modified contourite sediments by eroding, deforming, faulting, sliding, and depositing sediments. Mass-movement processes have resulted in the formation of recurrent mass-flow deposits, an enlargement of the submarine canyons and gully incisions, and basin-scale gravitational slides spreading above the Messinian Salinity Crisis salt layer. The Polopo, Aguilas and Gata slides are characterized by an extensional upslope domain that shapes the continental margin, and by a downslope contractional domain that shapes the abyssal plain with diapirs piercing (hemi)pelagites/sheet-like turbidites creating a seafloor dotted by numerous crests. The mass movements were mostly triggered by the interplay of the continental tectonic indentation of the Aguilas Arc with sedimentological factors over time. The indentation, which involves the progressively southeastward tectonic tilting of the whole land-sea region, likely generated a quasi-continuous oversteepening of the entire margin, thus reducing the stability of the contourites. In addition, tectonic tilting and subsidence of the abyssal plain favoured the flow of the underlying Messinian Salinity Crisis salt layer, contributing to the gravitational instability of the overlying sediments over large areas of the margin and abyssal plainThis research has been funding by the Spanish projects: DAMAGE (CGL2016-80687-RAEI/FEDER) and FAUCES (CTM2015-65461-C2-1-R); and the Junta de Andalucía projects: RNM-148 (AGORA) P18-RT-3275 and PAPEL (B-RNM-301-UGR18). [...] This work acknowledges to IGCP 640 - S4LIDE (Significance of Modern and Ancient Submarine Slope LandSLIDEs), and to the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S

Geohazard features of the north-western Sicily and Pantelleria

9 pages, 3 figures, supplemental material https://doi.org/10.1080/17445647.2024.2342931.-- Data availability statement: Department of Earth and Marine Science of the University of Palermo for institutional purposes, so their access will be available by contacting the reference people (attilio.sulliunipa.it) upon reasonable requestWe present maps of geohazard features identified across north-western Sicily and Pantelleria in the framework of the Magic project (MArine Geohazard along Italian Coasts), which involved Italian marine geological researchers in 2007-2013. These seafloor features were recognized using high-resolution bathymetry data and rely on the morphological expression of the seafloor and shallow sub-surface processes. The north-western Sicily is a complex continental margin, affected by morphodynamic, depositional, and tectonic processes. The Egadi offshore is controlled by fault escarpments and alternating retreating and progradational processes. Ustica and Pantelleria submerged edifices show the effect of volcanic activity. The Ustica seafloor is interested in volcanic, tectonic, and gravitational instability processes, while the Pantelleria offshore underwent erosive-depositional processes and the effect of bottom currents. Two levels of interpretation are represented: the physiographic domain at a scale of 1:250.000 and the morphological units and morpho-bathymetric elements at a 1:100.000 scaleThe Magic Project has been funded by the Italian Civil Protection Department. [...] With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)Peer reviewe

Seafloor mapping for geohazard assessment: state of the art

During the last two decades, increasing use of full-coverage sonic mapping of the seafloor has made us more aware of the large and different number of seafloor processes and events bearing significant geohazard potential. This awareness combines with the increasing use of the seafloor for infrastructure and with the high density of population and settlement on the coast. Seafloor mapping is the first step in making a census of the geohazard-bearing features present in a given offshore area. It often provides the only tool for a comprehensive, although non-specific, seafloor geohazard assessment over large areas that are scarcely groundtruthed by acoustic prospection and seafloor sampling. However, the characterization of geohazard features on a morphological basis alone is limited, and more detailed investigations are needed to define the character and state of activity of potentially hazardous features. Such investigations include the use of deep-tow or autonomous platforms designed to acquire high-resolution data at depth as well as in situ measurements, both being very expensive activities not applicable over large areas. Thus seafloor mapping is often not only the first and the main but also the only tool for a comprehensive seafloor geohazard assessment. This special issue represents an example of the diversity of approaches to seafloor geohazard assessment and summarizes the present state of this discipline. Both the diverse technologies applied and the specific aims of offshore geohazard assessment brought different communities to deal with the study of seafloor processes and events from remarkably distinct viewpoints. We identified three end members in offshore geohazard assessment: (1) geohazard assessment ‘‘sensu stricto’’, (2) ‘‘engineering’’ geohazard assessment, (3) ‘‘non-specific’’ geohazard assessment. These are being conducted by industry, academia and public agencies in charge of civil protection and land-use planning and management. Understanding the needs and geohazard perception of the different groups is a necessary step for a profitable collaboration in such an interesting and rapidly developing field of marine geologyThis volume was partially supported by the UNESCO and IUGS through project IGCP-511 ‘‘Submarine Mass Movements and Their consequences’’, currently superseded by IGCP project 585, ‘‘Earth’s continental MARgins: aSsessing geoHAzard from submarine Landslides (E-MARSHAL; http://www.igcp585.org) and of MaGIC project ‘‘Marine Geohazards along the Italian Coasts’’ (www.magicproject.it). Finally, National Civil Protection Department of Italy and namely Prof. B. de Bernardinis, are acknowledged not only for the aid they gave to the Ischia conference and to the volume but for supporting the MaGIC Project (Marine Geohazards along the Italian Coasts, www.magicproject.it) that is boosting a new wave of marine geology researches among the Italian marine geology communityPeer reviewe

Overview of the variability of Late Quaternary continental shelf deposits of the Italian peninsula

This paper documents the Late Quaternary (120 ka BP–present) stratigraphic architecture of Italian continental shelves through the interpretation of single-channel, very high-resolution seismic reflection profiles and from data derived from published studies, by using the high-resolution sequence stratigraphy framework. The result of this analysis provides a detailed reconstruction of the variability of shelf stratigraphy in relation to differences in physiography, sediment supply, structural framework and local factors. We distinguish four stratigraphic types: (1) wide shelves with high sediment supply (e.g. the central Adriatic and the central-northern Tyrrhenian shelves); (2) wide but sediment-starved shelves (e.g. the southern Latium shelf); (3) narrow shelves with high sediment supply (e.g. shelves located in the Ionian and southern Tyrrhenian Sea); and (4) narrow and sediment-starved shelves (shelves located around islands and archipelagos). Besides physiography, sediment supply and vertical movements, local factors and specific processes play a significant role in determining Late Quaternary stratal architecture and sedimentary facies. For example, the attributes of antecedent topography commonly seem to govern the formation and preservation of transgressive deposits, whereas the formation and preservation of falling stage and lowstand systems deposits can be hindered by the presence of canyons indenting the shelf edge and/or slope instability

An overview of the continental shelves of the world

This Memoir explores the variability and controlling processes of sedimentation, morphology and tectonics on the world\u27s continental shelves, with emphasis on their evolution during the last glacio-eustatic cycle. This work builds on some earlier volumes on continental shelves, notably those by Trumbul et al. (1958), Boillot (1978), De Batist & Jacobs (1996), Nittrouer et al. (2007) and Li et al. (2012) among others, although there has not been a previous comprehensive global-scale synthesis. The subject material presented here was developed in several International Geoscience Programmes (formerly the International Geological Correlation Programme, IGCP) concerned with shelves. Project 396 \u27Continental Shelves in the Quaternary\u27 (1996-2000) was followed by IGCP 464 \u27Continental Shelves during the Last Glacial Cycle: Knowledge and Applications\u27 (2001-2007) and finally by IGCP 526 \u27Risks, Resources and Record of the Past on the Continental Shelf\u27 (2007-2011). In this Memoir, 23 papers are devoted to the description of different aspects of shelves from all seven continents and which are representative of the world\u27s shelves. However, there remain significant gaps in our compilation. A glance at Figure 1.1 indicates the sparse coverage of data, particularly using modern techniques of investigation, for Africa, Russia and the Polar regions. However, new data are presented from some frontier provinces, such as Myanmar, Morocco and Ecuador