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The re-analysis of high-resolution seismic profiles collected along the narrow (2–9 km) shelf facing ∼90 km of the Calabro-Tyrrhenian coastline has enabled the reconstruction of its sequence-stratigraphic architecture, along with the quantification of sediment volumes accommodated during the last post-glacial sea level rise and highstand. The shelf volumes are compared with the gross volumes supplied by the short and steep rivers draining the uplifted hinterland area, obtained from morphometric analysis and inferred denudation rates (derived from uplift rates) of the drainage basins. The study area is divided in two main sectors based on the different morpho-stratigraphic setting and fluvial network controlling sediment distribution on the shelf. The Coastal Range sector is characterized by closely spaced mountainous rivers and narrow coastal plains; on the shelf, the post-LGM deposits show a main depocenter (up to 60 m thick) elongated ∼27 km parallel to the coastline. This shelf sector hosts up to 80% of the sediment sourced from rivers, with a small percentage of sediment loss, mainly related to off-shelf export along a network of shelf-indenting submarine canyons. Sediment deficit due to river aggradation is considered negligible based on the narrow and V-shaped thalwegs typical of the rivers in this sector. The Santa Eufemia sector is characterized by larger rivers and a wider coastal plain, with a major depocenter (up to 50 m thick) confined off the Amato River. In this sector, the entire post-LGM sequence accounts only for about 30% of the sediment supplied by rivers (60% considering only the HST), indicating that, in addition to sediment exported off-shelf, a significant part is trapped by river aggradation within the coastal plain. The volumetric comparison has also evidenced local but significant discrepancies in sedimentary budget between adjacent sub-sectors, likely related to the effect of northward-directed shelf currents on sediment distribution along the shelf. [ABSTRACT FROM AUTHOR]

The Ionian Sea in southern Italy is at the center of active interaction and convergence between the Eurasian and African–Adriatic plates in the Mediterranean. This area is seismically active with instrumentally and/or historically recorded Mw>7.0 earthquakes, and it is affected by recently discovered long strike-slip faults across the active Calabrian accretionary wedge. Many mud volcanoes occur on top of the wedge. A recently discovered one (called the Bortoluzzi Mud Volcano or BMV) was surveyed during the Seismofaults 2017 cruise (May 2017). High-resolution bathymetric backscatter surveys, seismic reflection profiles, geochemical and earthquake data, and a gravity core are used here to geologically, geochemically, and geophysically characterize this structure. The BMV is a circular feature ≃22 m high and ≃1100 m in diameter with steep slopes (up to a dip of 22 ∘). It sits atop the Calabrian accretionary wedge and a system of flower-like oblique-slip faults that are probably seismically active as demonstrated by earthquake hypocentral and focal data. Geochemistry of water samples from the seawater column on top of the BMV shows a significant contamination of the bottom waters from saline (evaporite-type) CH4 -dominated crustal-derived fluids similar to the fluids collected from a mud volcano located on the Calabria mainland over the same accretionary wedge. These results attest to the occurrence of open crustal pathways for fluids through the BMV down to at least the Messinian evaporites at about -3000 m. This evidence is also substantiated by helium isotope ratios and by comparison and contrast with different geochemical data from three seawater columns located over other active faults in the Ionian Sea area. One conclusion is that the BMV may be useful for tracking the seismic cycle of active faults through geochemical monitoring. Due to the widespread diffusion of mud volcanoes in seismically active settings, this study contributes to indicating a future path for the use of mud volcanoes in the monitoring and mitigation of natural hazards. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The Zannone Giant Pockmark (ZGP) is a shallow-water (<−150 m) giant depression located on the shelf off Zannone Island (Pontine Archipelago, central Tyrrhenian Sea, Italy), hosting active hydrothermal vents. The ZGP seabed displays different fluid-venting morphologies (pockmarks, lithified pavements, mounds, and cone-shaped structures) and widespread bacterial communities. In this study, we analyzed ROV (Remote Operated Vehicle) images to gain information on seabed geology and the textural, mineralogical, and geochemical composition of authigenic crusts and gravel-sized clasts sampled close to active emissions. ROV images show authigenic dome-shaped crusts composed of native sulfur associated with barite, gypsum, amorphous silica, and secondary hydrothermal minerals (illite–montmorillonite). The gravel-sized clasts are mostly rhyolites strongly affected by hydrothermal alteration (Alteration Index > 88; depletion of some mobile elements and enrichment of some base metals), causing feldspar-destruction, silicification, formation of hydrothermal phyllosilicates, and precipitation of disseminated pyrite. More intense alteration implying the complete obliteration of the primary mineralogy or fabric is represented by quartz-pyrite samples. ZGP seabed morphology and petro-geochemical features of deposits point to the possible occurrence of a sulfide system linked to the degassing of magma similar to that feeding the Pleistocene products of Ponza Island. [ABSTRACT FROM AUTHOR]

The Messina Strait, situated along the southern sector of the Italian peninsula, provides a good setting to study the source-to-basin relationships and, thus, the complete transect from continental to deep-marine environments. This work concerns the chemical and mineralogical composition of the fine-grained sediments collected along the Messina Strait, since the distribution of major and trace elements related to the mineralogical assemblages allow us the reconstruction of sedimentary evolution and geological processes affecting the studied sediments and, thus, the relationships developed between source area and sedimentary basin. Studied sediments are very-fine sand, silt and clay mainly phyllosilicates and quartz-bearing. Specifically, sediments located on submerged Calabrian and Sicilian slopes generally show high quartz content, whereas samples of the Calabrian and Sicilian continental slopes generally show high phyllosilicates content. Calcite and feldspars (plagioclase and K-feldspar) occur in different amounts. Few samples contain Fe-oxides. The geochemical signatures of the sediments reflect a provenance from felsic lithotypes. The A-CN-K diagram shows a linear trend parallel to A-CN join reflecting, primarily, weathering from granitoid rocks. This trend may result from non-steady state weathering conditions where active tectonism and uplift, as shown by morpho-structural conditions of the Messina Strait and its complex tectonic network, enhance mechanical erosion of mineralogical zones differentiated along weathering profiles developed on source rocks. Weathering efficiency at source area suggests weak intensity, related to a temperate Mediterranean climate similar to that characterizing the present-day study area. [ABSTRACT FROM AUTHOR]