Advances in Sedimentology and Coastal and Marine Geology—2nd Edition

The eleven papers in this Special Issue “Advances in Sedimentology and Coastal and Marine Geology—2nd Edition”, as listed subsequently, contribute to our geological knowledge on areas both inside and outside of the Mediterranean significantly. They cover Italy and beyond. In Italy, areas off shore of Somma–Vesuvius and Campi Flegrei (Naples Bay; Contribution 1); the Eastern Adventure Plateau (Sicily Channel, Southern Tyrrhenian Sea, Italy; Contribution 4); and the Volturno basin and the Massico structure (the Campania–Latium continental margin; Southern Tyrrhenian Sea, Italy; Contribution 11) are studied.

Outside of Italy, this Special Issue covers the Zhu III Depression in the Pearl River Mouth Basin (southeastern China; Contribution 2); Cangnan and the southeastern area of sea near Xiangshan in Zhejiang Province (eastern China; Contributions 3 and 5); Shandong Peninsula (China; Contribution 7); the lower reaches of the Changhua River and its estuary on Hainan Island (China; Contribution 8); the Central Indian Ocean Basin (CIOB; Contribution 9); and a shallow section of water (Wuke section) located in the western part of Sichuan Province in southern China (Contribution 10). Research outside of the Mediterranean predominates in this volume.

To outline the geological settings of the areas studied in this Special Issue, firstly, Naples Bay is one of the most hazardous active volcanic areas in the world, with three volcanic complexes: the Somma–Vesuvius, Campi Flegrei, and Ischia volcanoes (atop Mt. Epomeo). These volcanic complexes have been studied in depth, but only the most recent references on their geology, volcanology, and morpho-bathymetry are considered herein [1,2,3,4,5,6,7,8]. In this region, the geological hazard is very high [9,10,11,12,13,14,15,16]. Significant bradyseismic crises occurred in Campi Flegrei from 1969 to 1972 and from 1982 to 1984, and a new bradyseismic crisis is still in course. The bradyseism in Pozzuoli is part of ground uplift and subsidence affecting the Campi Flegrei area. This phenomenon is currently characterized by ground uplift that has accelerated in recent months and an ongoing seismic swarm. On 18 July 2025, a magnitude 4.0 seismic event was recorded that shook the entire area, with its epicenter between Pozzuoli and Bagnoli, but numerous earthquakes have previously occurred in Naples (https://terremoti.ingv.it/events, accessed on 18 July 2025). The situation is constantly being monitored by the Vesuvius Observatory, which has declared a yellow alert level and an “attention” operational phase.

The Volturno basin and the Massico structure in the Northern Campania Volcanic Zone (NCVZ) represent the seaward prolongation of Mt. Massico on the shore [17]. In this area, the stratigraphic architecture of the ignimbrites is constrained by wells and geological sections [17,18,19,20,21,22,23,24]. The Volturno basin consists of an emerged portion, including the Volturno delta, and a submerged portion, whose stratigraphic architecture consists of several seismo-stratigraphic units [20,21,22,23,25,26]. The Massico structure is the seaward prolongation of Mt. Massico, bounding the Volturno Plain towards the northwest. Off shore of Volturno, the Massico horst consists of Meso-Cenozoic carbonate sequences formed of flower structures.

The Sicily Channel is located in an intraplate rift where Sicily is displaced away from the African continent in the NE direction [27,28]. The structural lows in the Sicily Channel have also been interpreted as large and discrete pull-apart basins involving deep crustal levels within a wrench zone that has developed in front of the Africa–Europe collisional belt [29]. This rift in the Sicily Channel was created by mantle convection as the African lithosphere slab rolled back beneath the Tyrrhenian basin [30,31]. In particular, the seismo-stratigraphic setting [32], the paleo-shoreline configuration at the last glacial maximum [33], and the fluid uprising [34] in the Adventure Plateau have been analyzed in depth.

The Pearl River Mouth Basin is an extensional basin whose geodynamic relationships with the southeastern Eurasian margin have been studied extensively, together with its formation mechanisms and petroleum geology [35,36]. Its tectonic setting is controlled by two episodes of rifting of the attenuated continental crust along the South China margin, ranging in age between the late Cretaceous and the early Oligocene. This rifting has controlled the individuation of various segments of the basin, Zhu 1, Zhu 2, and Zhu 3, which are separated by local uplifts and are characterized by horst and graben structures, respectively, controlled by regional normal faults. In particular, the Zhu 3 Depression of the Pearl River Mouth Basin is studied in this Special Issue with respect to the formation mechanisms of normal faults and their meaning to the geological evolution of the basin [37].

Zhejiang Province is characterized by different geotectonic units, including the Yangtze Plate to the northwest, in tectonic contact with the South China fold system to the southeast along the Jiangshan–Shaoxing fault [38]. The South China fold system is divided further into the Chencai–Suichang uplift belt and the Wenzhou–Linhai geotectogene belt, whose boundary is the Yuyao–Lishui fault. This area has been extensively studied, both regarding the volcanic dykes in the offshore sector [39] and the occurrence of hazardous geological features [40]. In this volume, the geomorphological problems in its embayed sandy beaches have been studied [41].

Shandong Peninsula, located in eastern China, has a complex geological history influenced by its position within the North China Craton and its interactions with the Pacific Plate. The peninsula is characterized by a Precambrian basement, overlain by Mesozoic-Cenozoic sedimentary and magmatic rocks and affected by faulting and orogenic events. It has been studied from various angles, including its iron formations and the related geochemical data [42]; the stratigraphic and sedimentary evolution of its Holocene deposits, characterized by a clinoform pattern [43,44]; and its gold mineralization and deposits [45]. In this volume, the problems that have arisen during analyses of the provenance of the sediments deposited in the Northern Offshore Mud Area during the last 2000 years are considered [46].

The contributions to this Special Issue discuss mass extinctions, in particular that which occurred during the Late Ordovician [47]. This mass extinction has been interpreted as genetically related to a climatic and ecological crisis [48]. In the geological record, this represents one of the five greatest mass extinctions, genetically related to the growth and decay of the ice cap of the Gondwana continent. Benthic and planktonic organisms were involved in strong decay affecting the continental shelves of the Ordovician period [48]. These ecological communities returned to their pre-extinction levels during the Silurian, reaching levels similar to those in the Ordovician [48]. During the Phanerozoic, five main periods of mass extinction occurred [49]: the Ordovician–Silurian, the Late Devonian, the Permian–Triassic, the Triassic–Jurassic, and the Cretaceous–Paleogene. These events were characterized by significant and relatively rapid decreases in biodiversity. In particular, the Ordovician–Silurian extinction occurred around 440 million years ago and primarily impacted marine life. The Late Devonian extinction occurred 365 My ago, affecting marine organisms. The Permo–Triassic extinction was the most drastic and occurred at 252 My ago, with massive losses of both marine and terrestrial species. About 201 million years ago, the Triassic–Jurassic extinction paved the way for the rise of dinosaurs. The Cretaceous–Paleogene extinction, the most recent of the five, occurred 66 million years ago, famously wiping out non-avian dinosaurs [49].

Contribution 1 in this Special Issue analyzes the seismo-stratigraphic setting of the buried Somma–Vesuvius volcano (Contribution 1 in the list of contributions) [50]. Seven seismic units have been recognized and partly calibrated with well data for the Trecase 1 and Palazzo Reale wells. Its volcanic structures, previously interpreted as cryptodomes [51], have been interpreted as tuff rings based on their height/weight ratio on seismic interpretation and correlated with the tuff rings on shore at Campi Flegrei. A new and important volcanic seismic unit—a 5 m branch in the isopach of the Pomici di Avellino pyroclastic deposits—is recognized and interpreted, representing the important PDCs at Somma–Vesuvius [52].

Contribution 2 in the Special Issue takes the formation mechanisms of the NW-SE-trending normal faults bounding the Zhu 3 sub-basin of the Pearl River Mouth Basin as its subject [53]. Based on a structural analysis of their seismic profiles, these faults have been thoroughly structurally characterized, filling a previous gap in the research. In this way, extensional faults, dextral transtensional faults, and sinistral strike–slip faults are distinguished. The corresponding structural implications for the basin’s evolution have been analyzed, identifying tectonic inversion triggered by the reactivation of faults involving the basement.

Contribution 3 in this Special Issue is methodological in nature, establishing a novel method for estimating the undrained shear strength of marine soil based on CPTU tests (piezocone penetration tests) [54]. Key parameters and tests in the field of marine geotechnics have been considered, including the piezocone penetration test, the soil behavior type index, the undrained shear strength, and the consolidated quick direct shear test. Using data obtained from direct shear tests, a regression model has been constructed to explain the functional relationship between the soil behavior type index and the cone factor. The performance of this model was assessed through a comprehensive evaluation of metrics including the coefficient of determination, the root mean square error (RMSE), and the mean absolute error (MAE). The proposed methodology was tested in nearby marine project sites to confirm its applicability.

Contribution 4 in this Special Issue discusses the submarine volcanism in the Sicily Channel [55]. On the eastern side of the Adventure Plateau, a collection of five volcanoes known as the “Tetide volcanic cluster” creates a NW-SE alignment and is interpreted as the morphological expression of a failed rift. This volcanic alignment might be the remains of an unsuccessful attempt to create a rift that failed to produce another tectonic trough. Three volcano–tectonic phases have been distinguished, including a magmatic intrusion in the early Pliocene associated with a NW-SE normal fault that formed during the opening of the Pantelleria Graben; a Plio-Quaternary phase of quiescence; and a renewed magmatic intrusion through fissures or cracks that resulted in the late Quaternary volcanoes.

Contribution 5 in this Special Issue covers the coastal geomorphology and sedimentology of the sandy beaches in Zhejiang Province (eastern China) [56]. Field measurements on 75 accessible sandy beaches in Zhejiang with lengths greater than 100 m, including 30 mainland beaches and 45 island beaches, were carried out. Beach morphology was characterized according to the beach length (l), defined as the coastal length of a sandy beach, and averaged dry beach width (w), calculated as the arithmetic average of the width between the base (the foot of landward rocky cliff or the seawall) and the waterline at low tide, measured from each beach’s profile. The distribution patterns and geomorphological characteristics indicate that waves and tides have a prevalent influence to the north and south, respectively. The distribution patterns and geomorphological settings on these beaches are mainly affected by the embayment characteristics.

Contribution 6 in this Special Issue is more methodological and deals with marine geotechnics [57], including a geotechnical analysis of the physical and mechanical parameters of sediments and typical clay during a natural dewatering process. Four sediments were sampled from French river dams, and kaolin clay was used. The test procedures included monitoring the natural dewatering and undrained shear strength. Dewatering was characterized according to changes in the water content and calculation of the void ratio. The geotechnical characterization included calculating the variation in dry unit weight and the shear strength relationships. While the percentage of water drained followed a sigmoidal trend, a unique and linear correlation was found relating dry unit weight to solid particle weight as a function of the water content, as the sediments tested had a low clay content.

Contribution 7 in this Special Issue analyzed the area of mud off shore of the northern part of Shandong Peninsula, representing a source-to sink system in the continental shelf of China [58]. A source-to-sink analysis was used to study the sedimentary systems from areas of erosion (sources) to areas of deposition (sinks) and the processes of sediment transport along the way. A holistic approach that considers the relationships between the different segments of the system, such as catchments, continental shelves, slopes, and submarine fans, is used [59,60]. The mud wedge in Shandong Peninsula represents a subaqueous delta where sea level oscillations, shelf circulation patterns, monsoon evolution, sediment transport, and depositional processes have been recorded [61,62,63]. The comparative analysis of the clay mineral composition of samples from the surrounding rivers, along with ternary diagrams and cross plot analyses, suggests that these clay minerals mainly originate from the Yellow River, the rivers of the Shandong Peninsula, and the Yangtze River, highlighting the sediment’s multi-source characteristics.

Contribution 8 in this Special Issue studied the sedimentary dynamics in the lower reaches of the Changhua River and its estuary on Hainan Island [64]. Its sedimentological analysis facilitated the construction of a sediment distribution map in which gravelly sands and gravelly mud sands were predominant. Based on grain size parameters, topography, sediment sources, hydrodynamics, and sediment transport, the study area is divided into four sedimentary regions: the Northern Offshore Depositional Zone, the Central Offshore Depositional Zone, the Southern Offshore Depositional Zone, and the Downstream River Channel Depositional Zone. The trends in the sediment transport in the area were also distinguished. The sediments in the lower reaches of the Changhua River are mainly transported towards the south and the southwest according to Eulerian residual flow patterns, particularly in offshore areas.

Contribution 9 in this Special Issue deals with the morpho-bathymetric and structural setting of the Central Indian Ocean Basin, in particular the intraplate deformation zone [65], characterized by a block structure. Detailed morphotectonic studies were previously carried out in this area, dealing with its structural and geodynamic setting [66]. In this article [65], a linear block at 0.2–0.6 s with a branch-like shape in plain view is morphologically distinct from the other blocks. It represents a system of structural elements of different scales (folds, flexures, ruptures) forming a dextral transpressive tectonic regime. Gravimetric and magnetic data have been integrated with structural data, highlighting the close relationships that exist between the tectonic setting and gravimetric and magnetic anomalies. Multichannel seismic profiles portray the seismo-stratigraphic setting of the area, where key regional unconformities emerged in the Late Miocene and the Early Pliocene.

Contribution 10 in this Special Issue explains the mass extinction in the Late Ordovician as a result of anoxic events [67,68]. In particular, geochemical proxies were used to reconstruct the event stratigraphy in the Late Ordovician period. An enhanced chemical weathering rate (increased ⁸⁷Sr/⁸⁶Sr ratios) and a decreased intensity of chemical weathering (decreased CIA values) characterized the late Katian. The Hirnantian Glaciation was characterized by high ⁸⁷Sr/⁸⁶Sr ratios in carbonates and extremely low CIA values in shales, genetically related to the emersion of continents during lowstand periods and the glacial grinding of unweathered rocks. δ¹³C records and climate events for the Late Ordovician have been analyzed, comparing new data with previous data for the area. Climatic shifts and mass extinctions in the Late Ordovician were significantly impacted by changes in weathering. Increased weathering contributed to Katian extinction by inducing high primary production and the spread of anoxic seawater. The greatest rate of denudation and the least amount of chemical weathering during the Hirnantian Glaciation probably led to increased CO₂ release and helped to end glaciation.

Finally, Contribution 11 in this Special Issue provides seismo-stratigraphic data and geological interpretations on the filling of the Volturno basin in relation to the Massico structure. It describes the stratigraphic setting of the Campania continental margin, focusing on the ignimbrites in the Campania Volcanic Zone (CVZ) [17]. A geological section of the Volturno basin is integrated with the seismic profiles of Zone E, showing flower structures involving the Meso-Cenozoic carbonate basement. The stratigraphic correlations in the lithostratigraphic data for the wells are indicative of pyroclastic and alluvial deposits, which constitute the sedimentary material within the Volturno Plain, alongside volcanic lava (andesites and basalts) originating from the Villa Literno volcanic complex.